/*
   * This file implements the perfmon-2 subsystem which is used
   * to program the IA-64 Performance Monitoring Unit (PMU).
   *
   * The initial version of perfmon.c was written by
   * Ganesh Venkitachalam, IBM Corp.
   *
   * Then it was modified for perfmon-1.x by Stephane Eranian and
   * David Mosberger, Hewlett Packard Co.
   *
   * Version Perfmon-2.x is a rewrite of perfmon-1.x
   * by Stephane Eranian, Hewlett Packard Co.
   *

   * Copyright (C) 1999-2005  Hewlett Packard Co

   *               Stephane Eranian <eranian@hpl.hp.com>
   *               David Mosberger-Tang <davidm@hpl.hp.com>
   *
   * More information about perfmon available at:
   * 	http://www.hpl.hp.com/research/linux/perfmon
   */

  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/interrupt.h>

  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/init.h>
  #include <linux/vmalloc.h>
  #include <linux/mm.h>
  #include <linux/sysctl.h>
  #include <linux/list.h>
  #include <linux/file.h>
  #include <linux/poll.h>
  #include <linux/vfs.h>

  #include <linux/smp.h>

  #include <linux/pagemap.h>
  #include <linux/mount.h>

  #include <linux/bitops.h>

  #include <linux/capability.h>

  #include <linux/rcupdate.h>

  #include <linux/completion.h>

  #include <linux/tracehook.h>

  #include <linux/slab.h>

  
  #include <asm/errno.h>
  #include <asm/intrinsics.h>
  #include <asm/page.h>
  #include <asm/perfmon.h>
  #include <asm/processor.h>
  #include <asm/signal.h>
  #include <asm/system.h>
  #include <asm/uaccess.h>
  #include <asm/delay.h>
  
  #ifdef CONFIG_PERFMON
  /*
   * perfmon context state
   */
  #define PFM_CTX_UNLOADED	1	/* context is not loaded onto any task */
  #define PFM_CTX_LOADED		2	/* context is loaded onto a task */
  #define PFM_CTX_MASKED		3	/* context is loaded but monitoring is masked due to overflow */
  #define PFM_CTX_ZOMBIE		4	/* owner of the context is closing it */
  
  #define PFM_INVALID_ACTIVATION	(~0UL)

  #define PFM_NUM_PMC_REGS	64	/* PMC save area for ctxsw */
  #define PFM_NUM_PMD_REGS	64	/* PMD save area for ctxsw */

  /*
   * depth of message queue
   */
  #define PFM_MAX_MSGS		32
  #define PFM_CTXQ_EMPTY(g)	((g)->ctx_msgq_head == (g)->ctx_msgq_tail)
  
  /*
   * type of a PMU register (bitmask).
   * bitmask structure:
   * 	bit0   : register implemented
   * 	bit1   : end marker
   * 	bit2-3 : reserved
   * 	bit4   : pmc has pmc.pm
   * 	bit5   : pmc controls a counter (has pmc.oi), pmd is used as counter
   * 	bit6-7 : register type
   * 	bit8-31: reserved
   */
  #define PFM_REG_NOTIMPL		0x0 /* not implemented at all */
  #define PFM_REG_IMPL		0x1 /* register implemented */
  #define PFM_REG_END		0x2 /* end marker */
  #define PFM_REG_MONITOR		(0x1<<4|PFM_REG_IMPL) /* a PMC with a pmc.pm field only */
  #define PFM_REG_COUNTING	(0x2<<4|PFM_REG_MONITOR) /* a monitor + pmc.oi+ PMD used as a counter */
  #define PFM_REG_CONTROL		(0x4<<4|PFM_REG_IMPL) /* PMU control register */
  #define	PFM_REG_CONFIG		(0x8<<4|PFM_REG_IMPL) /* configuration register */
  #define PFM_REG_BUFFER	 	(0xc<<4|PFM_REG_IMPL) /* PMD used as buffer */
  
  #define PMC_IS_LAST(i)	(pmu_conf->pmc_desc[i].type & PFM_REG_END)
  #define PMD_IS_LAST(i)	(pmu_conf->pmd_desc[i].type & PFM_REG_END)
  
  #define PMC_OVFL_NOTIFY(ctx, i)	((ctx)->ctx_pmds[i].flags &  PFM_REGFL_OVFL_NOTIFY)
  
  /* i assumed unsigned */
  #define PMC_IS_IMPL(i)	  (i< PMU_MAX_PMCS && (pmu_conf->pmc_desc[i].type & PFM_REG_IMPL))
  #define PMD_IS_IMPL(i)	  (i< PMU_MAX_PMDS && (pmu_conf->pmd_desc[i].type & PFM_REG_IMPL))
  
  /* XXX: these assume that register i is implemented */
  #define PMD_IS_COUNTING(i) ((pmu_conf->pmd_desc[i].type & PFM_REG_COUNTING) == PFM_REG_COUNTING)
  #define PMC_IS_COUNTING(i) ((pmu_conf->pmc_desc[i].type & PFM_REG_COUNTING) == PFM_REG_COUNTING)
  #define PMC_IS_MONITOR(i)  ((pmu_conf->pmc_desc[i].type & PFM_REG_MONITOR)  == PFM_REG_MONITOR)
  #define PMC_IS_CONTROL(i)  ((pmu_conf->pmc_desc[i].type & PFM_REG_CONTROL)  == PFM_REG_CONTROL)
  
  #define PMC_DFL_VAL(i)     pmu_conf->pmc_desc[i].default_value
  #define PMC_RSVD_MASK(i)   pmu_conf->pmc_desc[i].reserved_mask
  #define PMD_PMD_DEP(i)	   pmu_conf->pmd_desc[i].dep_pmd[0]
  #define PMC_PMD_DEP(i)	   pmu_conf->pmc_desc[i].dep_pmd[0]
  
  #define PFM_NUM_IBRS	  IA64_NUM_DBG_REGS
  #define PFM_NUM_DBRS	  IA64_NUM_DBG_REGS
  
  #define CTX_OVFL_NOBLOCK(c)	((c)->ctx_fl_block == 0)
  #define CTX_HAS_SMPL(c)		((c)->ctx_fl_is_sampling)
  #define PFM_CTX_TASK(h)		(h)->ctx_task
  
  #define PMU_PMC_OI		5 /* position of pmc.oi bit */
  
  /* XXX: does not support more than 64 PMDs */
  #define CTX_USED_PMD(ctx, mask) (ctx)->ctx_used_pmds[0] |= (mask)
  #define CTX_IS_USED_PMD(ctx, c) (((ctx)->ctx_used_pmds[0] & (1UL << (c))) != 0UL)
  
  #define CTX_USED_MONITOR(ctx, mask) (ctx)->ctx_used_monitors[0] |= (mask)
  
  #define CTX_USED_IBR(ctx,n) 	(ctx)->ctx_used_ibrs[(n)>>6] |= 1UL<< ((n) % 64)
  #define CTX_USED_DBR(ctx,n) 	(ctx)->ctx_used_dbrs[(n)>>6] |= 1UL<< ((n) % 64)
  #define CTX_USES_DBREGS(ctx)	(((pfm_context_t *)(ctx))->ctx_fl_using_dbreg==1)
  #define PFM_CODE_RR	0	/* requesting code range restriction */
  #define PFM_DATA_RR	1	/* requestion data range restriction */
  
  #define PFM_CPUINFO_CLEAR(v)	pfm_get_cpu_var(pfm_syst_info) &= ~(v)
  #define PFM_CPUINFO_SET(v)	pfm_get_cpu_var(pfm_syst_info) |= (v)
  #define PFM_CPUINFO_GET()	pfm_get_cpu_var(pfm_syst_info)
  
  #define RDEP(x)	(1UL<<(x))
  
  /*
   * context protection macros
   * in SMP:
   * 	- we need to protect against CPU concurrency (spin_lock)
   * 	- we need to protect against PMU overflow interrupts (local_irq_disable)
   * in UP:
   * 	- we need to protect against PMU overflow interrupts (local_irq_disable)
   *

   * spin_lock_irqsave()/spin_unlock_irqrestore():

   * 	in SMP: local_irq_disable + spin_lock
   * 	in UP : local_irq_disable
   *
   * spin_lock()/spin_lock():
   * 	in UP : removed automatically
   * 	in SMP: protect against context accesses from other CPU. interrupts
   * 	        are not masked. This is useful for the PMU interrupt handler
   * 	        because we know we will not get PMU concurrency in that code.
   */
  #define PROTECT_CTX(c, f) \
  	do {  \

  		DPRINT(("spinlock_irq_save ctx %p by [%d]
  ", c, task_pid_nr(current))); \

  		spin_lock_irqsave(&(c)->ctx_lock, f); \

  		DPRINT(("spinlocked ctx %p  by [%d]
  ", c, task_pid_nr(current))); \

  	} while(0)
  
  #define UNPROTECT_CTX(c, f) \
  	do { \

  		DPRINT(("spinlock_irq_restore ctx %p by [%d]
  ", c, task_pid_nr(current))); \

  		spin_unlock_irqrestore(&(c)->ctx_lock, f); \
  	} while(0)
  
  #define PROTECT_CTX_NOPRINT(c, f) \
  	do {  \
  		spin_lock_irqsave(&(c)->ctx_lock, f); \
  	} while(0)
  
  
  #define UNPROTECT_CTX_NOPRINT(c, f) \
  	do { \
  		spin_unlock_irqrestore(&(c)->ctx_lock, f); \
  	} while(0)
  
  
  #define PROTECT_CTX_NOIRQ(c) \
  	do {  \
  		spin_lock(&(c)->ctx_lock); \
  	} while(0)
  
  #define UNPROTECT_CTX_NOIRQ(c) \
  	do { \
  		spin_unlock(&(c)->ctx_lock); \
  	} while(0)
  
  
  #ifdef CONFIG_SMP
  
  #define GET_ACTIVATION()	pfm_get_cpu_var(pmu_activation_number)
  #define INC_ACTIVATION()	pfm_get_cpu_var(pmu_activation_number)++
  #define SET_ACTIVATION(c)	(c)->ctx_last_activation = GET_ACTIVATION()
  
  #else /* !CONFIG_SMP */
  #define SET_ACTIVATION(t) 	do {} while(0)
  #define GET_ACTIVATION(t) 	do {} while(0)
  #define INC_ACTIVATION(t) 	do {} while(0)
  #endif /* CONFIG_SMP */
  
  #define SET_PMU_OWNER(t, c)	do { pfm_get_cpu_var(pmu_owner) = (t); pfm_get_cpu_var(pmu_ctx) = (c); } while(0)
  #define GET_PMU_OWNER()		pfm_get_cpu_var(pmu_owner)
  #define GET_PMU_CTX()		pfm_get_cpu_var(pmu_ctx)
  
  #define LOCK_PFS(g)	    	spin_lock_irqsave(&pfm_sessions.pfs_lock, g)
  #define UNLOCK_PFS(g)	    	spin_unlock_irqrestore(&pfm_sessions.pfs_lock, g)
  
  #define PFM_REG_RETFLAG_SET(flags, val)	do { flags &= ~PFM_REG_RETFL_MASK; flags |= (val); } while(0)
  
  /*
   * cmp0 must be the value of pmc0
   */
  #define PMC0_HAS_OVFL(cmp0)  (cmp0 & ~0x1UL)
  
  #define PFMFS_MAGIC 0xa0b4d889
  
  /*
   * debugging
   */
  #define PFM_DEBUGGING 1
  #ifdef PFM_DEBUGGING
  #define DPRINT(a) \
  	do { \

  		if (unlikely(pfm_sysctl.debug >0)) { printk("%s.%d: CPU%d [%d] ", __func__, __LINE__, smp_processor_id(), task_pid_nr(current)); printk a; } \

  	} while (0)
  
  #define DPRINT_ovfl(a) \
  	do { \

  		if (unlikely(pfm_sysctl.debug > 0 && pfm_sysctl.debug_ovfl >0)) { printk("%s.%d: CPU%d [%d] ", __func__, __LINE__, smp_processor_id(), task_pid_nr(current)); printk a; } \

  	} while (0)
  #endif
  
  /*
   * 64-bit software counter structure
   *
   * the next_reset_type is applied to the next call to pfm_reset_regs()
   */
  typedef struct {
  	unsigned long	val;		/* virtual 64bit counter value */
  	unsigned long	lval;		/* last reset value */
  	unsigned long	long_reset;	/* reset value on sampling overflow */
  	unsigned long	short_reset;    /* reset value on overflow */
  	unsigned long	reset_pmds[4];  /* which other pmds to reset when this counter overflows */
  	unsigned long	smpl_pmds[4];   /* which pmds are accessed when counter overflow */
  	unsigned long	seed;		/* seed for random-number generator */
  	unsigned long	mask;		/* mask for random-number generator */
  	unsigned int 	flags;		/* notify/do not notify */
  	unsigned long	eventid;	/* overflow event identifier */
  } pfm_counter_t;
  
  /*
   * context flags
   */
  typedef struct {
  	unsigned int block:1;		/* when 1, task will blocked on user notifications */
  	unsigned int system:1;		/* do system wide monitoring */
  	unsigned int using_dbreg:1;	/* using range restrictions (debug registers) */
  	unsigned int is_sampling:1;	/* true if using a custom format */
  	unsigned int excl_idle:1;	/* exclude idle task in system wide session */
  	unsigned int going_zombie:1;	/* context is zombie (MASKED+blocking) */
  	unsigned int trap_reason:2;	/* reason for going into pfm_handle_work() */
  	unsigned int no_msg:1;		/* no message sent on overflow */
  	unsigned int can_restart:1;	/* allowed to issue a PFM_RESTART */
  	unsigned int reserved:22;
  } pfm_context_flags_t;
  
  #define PFM_TRAP_REASON_NONE		0x0	/* default value */
  #define PFM_TRAP_REASON_BLOCK		0x1	/* we need to block on overflow */
  #define PFM_TRAP_REASON_RESET		0x2	/* we need to reset PMDs */
  
  
  /*
   * perfmon context: encapsulates all the state of a monitoring session
   */
  
  typedef struct pfm_context {
  	spinlock_t		ctx_lock;		/* context protection */
  
  	pfm_context_flags_t	ctx_flags;		/* bitmask of flags  (block reason incl.) */
  	unsigned int		ctx_state;		/* state: active/inactive (no bitfield) */
  
  	struct task_struct 	*ctx_task;		/* task to which context is attached */
  
  	unsigned long		ctx_ovfl_regs[4];	/* which registers overflowed (notification) */

  	struct completion	ctx_restart_done;  	/* use for blocking notification mode */

  
  	unsigned long		ctx_used_pmds[4];	/* bitmask of PMD used            */
  	unsigned long		ctx_all_pmds[4];	/* bitmask of all accessible PMDs */
  	unsigned long		ctx_reload_pmds[4];	/* bitmask of force reload PMD on ctxsw in */
  
  	unsigned long		ctx_all_pmcs[4];	/* bitmask of all accessible PMCs */
  	unsigned long		ctx_reload_pmcs[4];	/* bitmask of force reload PMC on ctxsw in */
  	unsigned long		ctx_used_monitors[4];	/* bitmask of monitor PMC being used */

  	unsigned long		ctx_pmcs[PFM_NUM_PMC_REGS];	/*  saved copies of PMC values */

  
  	unsigned int		ctx_used_ibrs[1];		/* bitmask of used IBR (speedup ctxsw in) */
  	unsigned int		ctx_used_dbrs[1];		/* bitmask of used DBR (speedup ctxsw in) */
  	unsigned long		ctx_dbrs[IA64_NUM_DBG_REGS];	/* DBR values (cache) when not loaded */
  	unsigned long		ctx_ibrs[IA64_NUM_DBG_REGS];	/* IBR values (cache) when not loaded */

  	pfm_counter_t		ctx_pmds[PFM_NUM_PMD_REGS]; /* software state for PMDS */
  
  	unsigned long		th_pmcs[PFM_NUM_PMC_REGS];	/* PMC thread save state */
  	unsigned long		th_pmds[PFM_NUM_PMD_REGS];	/* PMD thread save state */

  	unsigned long		ctx_saved_psr_up;	/* only contains psr.up value */

  
  	unsigned long		ctx_last_activation;	/* context last activation number for last_cpu */
  	unsigned int		ctx_last_cpu;		/* CPU id of current or last CPU used (SMP only) */
  	unsigned int		ctx_cpu;		/* cpu to which perfmon is applied (system wide) */
  
  	int			ctx_fd;			/* file descriptor used my this context */
  	pfm_ovfl_arg_t		ctx_ovfl_arg;		/* argument to custom buffer format handler */
  
  	pfm_buffer_fmt_t	*ctx_buf_fmt;		/* buffer format callbacks */
  	void			*ctx_smpl_hdr;		/* points to sampling buffer header kernel vaddr */
  	unsigned long		ctx_smpl_size;		/* size of sampling buffer */
  	void			*ctx_smpl_vaddr;	/* user level virtual address of smpl buffer */
  
  	wait_queue_head_t 	ctx_msgq_wait;
  	pfm_msg_t		ctx_msgq[PFM_MAX_MSGS];
  	int			ctx_msgq_head;
  	int			ctx_msgq_tail;
  	struct fasync_struct	*ctx_async_queue;
  
  	wait_queue_head_t 	ctx_zombieq;		/* termination cleanup wait queue */
  } pfm_context_t;
  
  /*
   * magic number used to verify that structure is really
   * a perfmon context
   */
  #define PFM_IS_FILE(f)		((f)->f_op == &pfm_file_ops)
  
  #define PFM_GET_CTX(t)	 	((pfm_context_t *)(t)->thread.pfm_context)
  
  #ifdef CONFIG_SMP
  #define SET_LAST_CPU(ctx, v)	(ctx)->ctx_last_cpu = (v)
  #define GET_LAST_CPU(ctx)	(ctx)->ctx_last_cpu
  #else
  #define SET_LAST_CPU(ctx, v)	do {} while(0)
  #define GET_LAST_CPU(ctx)	do {} while(0)
  #endif
  
  
  #define ctx_fl_block		ctx_flags.block
  #define ctx_fl_system		ctx_flags.system
  #define ctx_fl_using_dbreg	ctx_flags.using_dbreg
  #define ctx_fl_is_sampling	ctx_flags.is_sampling
  #define ctx_fl_excl_idle	ctx_flags.excl_idle
  #define ctx_fl_going_zombie	ctx_flags.going_zombie
  #define ctx_fl_trap_reason	ctx_flags.trap_reason
  #define ctx_fl_no_msg		ctx_flags.no_msg
  #define ctx_fl_can_restart	ctx_flags.can_restart
  
  #define PFM_SET_WORK_PENDING(t, v)	do { (t)->thread.pfm_needs_checking = v; } while(0);
  #define PFM_GET_WORK_PENDING(t)		(t)->thread.pfm_needs_checking
  
  /*
   * global information about all sessions
   * mostly used to synchronize between system wide and per-process
   */
  typedef struct {
  	spinlock_t		pfs_lock;		   /* lock the structure */
  
  	unsigned int		pfs_task_sessions;	   /* number of per task sessions */
  	unsigned int		pfs_sys_sessions;	   /* number of per system wide sessions */
  	unsigned int		pfs_sys_use_dbregs;	   /* incremented when a system wide session uses debug regs */
  	unsigned int		pfs_ptrace_use_dbregs;	   /* incremented when a process uses debug regs */
  	struct task_struct	*pfs_sys_session[NR_CPUS]; /* point to task owning a system-wide session */
  } pfm_session_t;
  
  /*
   * information about a PMC or PMD.
   * dep_pmd[]: a bitmask of dependent PMD registers
   * dep_pmc[]: a bitmask of dependent PMC registers
   */
  typedef int (*pfm_reg_check_t)(struct task_struct *task, pfm_context_t *ctx, unsigned int cnum, unsigned long *val, struct pt_regs *regs);
  typedef struct {
  	unsigned int		type;
  	int			pm_pos;
  	unsigned long		default_value;	/* power-on default value */
  	unsigned long		reserved_mask;	/* bitmask of reserved bits */
  	pfm_reg_check_t		read_check;
  	pfm_reg_check_t		write_check;
  	unsigned long		dep_pmd[4];
  	unsigned long		dep_pmc[4];
  } pfm_reg_desc_t;
  
  /* assume cnum is a valid monitor */
  #define PMC_PM(cnum, val)	(((val) >> (pmu_conf->pmc_desc[cnum].pm_pos)) & 0x1)
  
  /*
   * This structure is initialized at boot time and contains
   * a description of the PMU main characteristics.
   *
   * If the probe function is defined, detection is based
   * on its return value: 
   * 	- 0 means recognized PMU
   * 	- anything else means not supported
   * When the probe function is not defined, then the pmu_family field
   * is used and it must match the host CPU family such that:
   * 	- cpu->family & config->pmu_family != 0
   */
  typedef struct {
  	unsigned long  ovfl_val;	/* overflow value for counters */
  
  	pfm_reg_desc_t *pmc_desc;	/* detailed PMC register dependencies descriptions */
  	pfm_reg_desc_t *pmd_desc;	/* detailed PMD register dependencies descriptions */
  
  	unsigned int   num_pmcs;	/* number of PMCS: computed at init time */
  	unsigned int   num_pmds;	/* number of PMDS: computed at init time */
  	unsigned long  impl_pmcs[4];	/* bitmask of implemented PMCS */
  	unsigned long  impl_pmds[4];	/* bitmask of implemented PMDS */
  
  	char	      *pmu_name;	/* PMU family name */
  	unsigned int  pmu_family;	/* cpuid family pattern used to identify pmu */
  	unsigned int  flags;		/* pmu specific flags */
  	unsigned int  num_ibrs;		/* number of IBRS: computed at init time */
  	unsigned int  num_dbrs;		/* number of DBRS: computed at init time */
  	unsigned int  num_counters;	/* PMC/PMD counting pairs : computed at init time */
  	int           (*probe)(void);   /* customized probe routine */
  	unsigned int  use_rr_dbregs:1;	/* set if debug registers used for range restriction */
  } pmu_config_t;
  /*
   * PMU specific flags
   */
  #define PFM_PMU_IRQ_RESEND	1	/* PMU needs explicit IRQ resend */
  
  /*
   * debug register related type definitions
   */
  typedef struct {
  	unsigned long ibr_mask:56;
  	unsigned long ibr_plm:4;
  	unsigned long ibr_ig:3;
  	unsigned long ibr_x:1;
  } ibr_mask_reg_t;
  
  typedef struct {
  	unsigned long dbr_mask:56;
  	unsigned long dbr_plm:4;
  	unsigned long dbr_ig:2;
  	unsigned long dbr_w:1;
  	unsigned long dbr_r:1;
  } dbr_mask_reg_t;
  
  typedef union {
  	unsigned long  val;
  	ibr_mask_reg_t ibr;
  	dbr_mask_reg_t dbr;
  } dbreg_t;
  
  
  /*
   * perfmon command descriptions
   */
  typedef struct {
  	int		(*cmd_func)(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs);
  	char		*cmd_name;
  	int		cmd_flags;
  	unsigned int	cmd_narg;
  	size_t		cmd_argsize;
  	int		(*cmd_getsize)(void *arg, size_t *sz);
  } pfm_cmd_desc_t;
  
  #define PFM_CMD_FD		0x01	/* command requires a file descriptor */
  #define PFM_CMD_ARG_READ	0x02	/* command must read argument(s) */
  #define PFM_CMD_ARG_RW		0x04	/* command must read/write argument(s) */
  #define PFM_CMD_STOP		0x08	/* command does not work on zombie context */
  
  
  #define PFM_CMD_NAME(cmd)	pfm_cmd_tab[(cmd)].cmd_name
  #define PFM_CMD_READ_ARG(cmd)	(pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_ARG_READ)
  #define PFM_CMD_RW_ARG(cmd)	(pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_ARG_RW)
  #define PFM_CMD_USE_FD(cmd)	(pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_FD)
  #define PFM_CMD_STOPPED(cmd)	(pfm_cmd_tab[(cmd)].cmd_flags & PFM_CMD_STOP)
  
  #define PFM_CMD_ARG_MANY	-1 /* cannot be zero */
  
  typedef struct {

  	unsigned long pfm_spurious_ovfl_intr_count;	/* keep track of spurious ovfl interrupts */
  	unsigned long pfm_replay_ovfl_intr_count;	/* keep track of replayed ovfl interrupts */
  	unsigned long pfm_ovfl_intr_count; 		/* keep track of ovfl interrupts */
  	unsigned long pfm_ovfl_intr_cycles;		/* cycles spent processing ovfl interrupts */
  	unsigned long pfm_ovfl_intr_cycles_min;		/* min cycles spent processing ovfl interrupts */
  	unsigned long pfm_ovfl_intr_cycles_max;		/* max cycles spent processing ovfl interrupts */
  	unsigned long pfm_smpl_handler_calls;
  	unsigned long pfm_smpl_handler_cycles;
  	char pad[SMP_CACHE_BYTES] ____cacheline_aligned;
  } pfm_stats_t;
  
  /*
   * perfmon internal variables
   */
  static pfm_stats_t		pfm_stats[NR_CPUS];
  static pfm_session_t		pfm_sessions;	/* global sessions information */

  static DEFINE_SPINLOCK(pfm_alt_install_check);

  static pfm_intr_handler_desc_t  *pfm_alt_intr_handler;

  static struct proc_dir_entry 	*perfmon_dir;
  static pfm_uuid_t		pfm_null_uuid = {0,};
  
  static spinlock_t		pfm_buffer_fmt_lock;
  static LIST_HEAD(pfm_buffer_fmt_list);
  
  static pmu_config_t		*pmu_conf;
  
  /* sysctl() controls */

  pfm_sysctl_t pfm_sysctl;
  EXPORT_SYMBOL(pfm_sysctl);

  
  static ctl_table pfm_ctl_table[]={

  	{

  		.procname	= "debug",
  		.data		= &pfm_sysctl.debug,
  		.maxlen		= sizeof(int),
  		.mode		= 0666,

  		.proc_handler	= proc_dointvec,

  	},
  	{

  		.procname	= "debug_ovfl",
  		.data		= &pfm_sysctl.debug_ovfl,
  		.maxlen		= sizeof(int),
  		.mode		= 0666,

  		.proc_handler	= proc_dointvec,

  	},
  	{

  		.procname	= "fastctxsw",
  		.data		= &pfm_sysctl.fastctxsw,
  		.maxlen		= sizeof(int),
  		.mode		= 0600,

  		.proc_handler	= proc_dointvec,

  	},
  	{

  		.procname	= "expert_mode",
  		.data		= &pfm_sysctl.expert_mode,
  		.maxlen		= sizeof(int),
  		.mode		= 0600,

  		.proc_handler	= proc_dointvec,

  	},
  	{}

  };
  static ctl_table pfm_sysctl_dir[] = {

  	{

  		.procname	= "perfmon",

  		.mode		= 0555,

  		.child		= pfm_ctl_table,
  	},
   	{}

  };
  static ctl_table pfm_sysctl_root[] = {

  	{

  		.procname	= "kernel",

  		.mode		= 0555,

  		.child		= pfm_sysctl_dir,
  	},
   	{}

  };
  static struct ctl_table_header *pfm_sysctl_header;
  
  static int pfm_context_unload(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs);

  
  #define pfm_get_cpu_var(v)		__ia64_per_cpu_var(v)
  #define pfm_get_cpu_data(a,b)		per_cpu(a, b)
  
  static inline void
  pfm_put_task(struct task_struct *task)
  {
  	if (task != current) put_task_struct(task);
  }
  
  static inline void

  pfm_reserve_page(unsigned long a)
  {
  	SetPageReserved(vmalloc_to_page((void *)a));
  }
  static inline void
  pfm_unreserve_page(unsigned long a)
  {
  	ClearPageReserved(vmalloc_to_page((void*)a));
  }
  
  static inline unsigned long
  pfm_protect_ctx_ctxsw(pfm_context_t *x)
  {
  	spin_lock(&(x)->ctx_lock);
  	return 0UL;
  }

  static inline void

  pfm_unprotect_ctx_ctxsw(pfm_context_t *x, unsigned long f)
  {
  	spin_unlock(&(x)->ctx_lock);
  }
  
  static inline unsigned int
  pfm_do_munmap(struct mm_struct *mm, unsigned long addr, size_t len, int acct)
  {
  	return do_munmap(mm, addr, len);
  }
  
  static inline unsigned long 
  pfm_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, unsigned long pgoff, unsigned long flags, unsigned long exec)
  {
  	return get_unmapped_area(file, addr, len, pgoff, flags);
  }

  /* forward declaration */

  static const struct dentry_operations pfmfs_dentry_operations;

  static struct dentry *
  pfmfs_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data)

  {

  	return mount_pseudo(fs_type, "pfm:", NULL, &pfmfs_dentry_operations,
  			PFMFS_MAGIC);

  }
  
  static struct file_system_type pfm_fs_type = {
  	.name     = "pfmfs",

  	.mount    = pfmfs_mount,

  	.kill_sb  = kill_anon_super,
  };
  
  DEFINE_PER_CPU(unsigned long, pfm_syst_info);
  DEFINE_PER_CPU(struct task_struct *, pmu_owner);
  DEFINE_PER_CPU(pfm_context_t  *, pmu_ctx);
  DEFINE_PER_CPU(unsigned long, pmu_activation_number);

  EXPORT_PER_CPU_SYMBOL_GPL(pfm_syst_info);

  
  
  /* forward declaration */

  static const struct file_operations pfm_file_ops;

  
  /*
   * forward declarations
   */
  #ifndef CONFIG_SMP
  static void pfm_lazy_save_regs (struct task_struct *ta);
  #endif
  
  void dump_pmu_state(const char *);
  static int pfm_write_ibr_dbr(int mode, pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs);
  
  #include "perfmon_itanium.h"
  #include "perfmon_mckinley.h"

  #include "perfmon_montecito.h"

  #include "perfmon_generic.h"
  
  static pmu_config_t *pmu_confs[]={

  	&pmu_conf_mont,

  	&pmu_conf_mck,
  	&pmu_conf_ita,
  	&pmu_conf_gen, /* must be last */
  	NULL
  };
  
  
  static int pfm_end_notify_user(pfm_context_t *ctx);
  
  static inline void
  pfm_clear_psr_pp(void)
  {
  	ia64_rsm(IA64_PSR_PP);
  	ia64_srlz_i();
  }
  
  static inline void
  pfm_set_psr_pp(void)
  {
  	ia64_ssm(IA64_PSR_PP);
  	ia64_srlz_i();
  }
  
  static inline void
  pfm_clear_psr_up(void)
  {
  	ia64_rsm(IA64_PSR_UP);
  	ia64_srlz_i();
  }
  
  static inline void
  pfm_set_psr_up(void)
  {
  	ia64_ssm(IA64_PSR_UP);
  	ia64_srlz_i();
  }
  
  static inline unsigned long
  pfm_get_psr(void)
  {
  	unsigned long tmp;
  	tmp = ia64_getreg(_IA64_REG_PSR);
  	ia64_srlz_i();
  	return tmp;
  }
  
  static inline void
  pfm_set_psr_l(unsigned long val)
  {
  	ia64_setreg(_IA64_REG_PSR_L, val);
  	ia64_srlz_i();
  }
  
  static inline void
  pfm_freeze_pmu(void)
  {
  	ia64_set_pmc(0,1UL);
  	ia64_srlz_d();
  }
  
  static inline void
  pfm_unfreeze_pmu(void)
  {
  	ia64_set_pmc(0,0UL);
  	ia64_srlz_d();
  }
  
  static inline void
  pfm_restore_ibrs(unsigned long *ibrs, unsigned int nibrs)
  {
  	int i;
  
  	for (i=0; i < nibrs; i++) {
  		ia64_set_ibr(i, ibrs[i]);
  		ia64_dv_serialize_instruction();
  	}
  	ia64_srlz_i();
  }
  
  static inline void
  pfm_restore_dbrs(unsigned long *dbrs, unsigned int ndbrs)
  {
  	int i;
  
  	for (i=0; i < ndbrs; i++) {
  		ia64_set_dbr(i, dbrs[i]);
  		ia64_dv_serialize_data();
  	}
  	ia64_srlz_d();
  }
  
  /*
   * PMD[i] must be a counter. no check is made
   */
  static inline unsigned long
  pfm_read_soft_counter(pfm_context_t *ctx, int i)
  {
  	return ctx->ctx_pmds[i].val + (ia64_get_pmd(i) & pmu_conf->ovfl_val);
  }
  
  /*
   * PMD[i] must be a counter. no check is made
   */
  static inline void
  pfm_write_soft_counter(pfm_context_t *ctx, int i, unsigned long val)
  {
  	unsigned long ovfl_val = pmu_conf->ovfl_val;
  
  	ctx->ctx_pmds[i].val = val  & ~ovfl_val;
  	/*
  	 * writing to unimplemented part is ignore, so we do not need to
  	 * mask off top part
  	 */
  	ia64_set_pmd(i, val & ovfl_val);
  }
  
  static pfm_msg_t *
  pfm_get_new_msg(pfm_context_t *ctx)
  {
  	int idx, next;
  
  	next = (ctx->ctx_msgq_tail+1) % PFM_MAX_MSGS;
  
  	DPRINT(("ctx_fd=%p head=%d tail=%d
  ", ctx, ctx->ctx_msgq_head, ctx->ctx_msgq_tail));
  	if (next == ctx->ctx_msgq_head) return NULL;
  
   	idx = 	ctx->ctx_msgq_tail;
  	ctx->ctx_msgq_tail = next;
  
  	DPRINT(("ctx=%p head=%d tail=%d msg=%d
  ", ctx, ctx->ctx_msgq_head, ctx->ctx_msgq_tail, idx));
  
  	return ctx->ctx_msgq+idx;
  }
  
  static pfm_msg_t *
  pfm_get_next_msg(pfm_context_t *ctx)
  {
  	pfm_msg_t *msg;
  
  	DPRINT(("ctx=%p head=%d tail=%d
  ", ctx, ctx->ctx_msgq_head, ctx->ctx_msgq_tail));
  
  	if (PFM_CTXQ_EMPTY(ctx)) return NULL;
  
  	/*
  	 * get oldest message
  	 */
  	msg = ctx->ctx_msgq+ctx->ctx_msgq_head;
  
  	/*
  	 * and move forward
  	 */
  	ctx->ctx_msgq_head = (ctx->ctx_msgq_head+1) % PFM_MAX_MSGS;
  
  	DPRINT(("ctx=%p head=%d tail=%d type=%d
  ", ctx, ctx->ctx_msgq_head, ctx->ctx_msgq_tail, msg->pfm_gen_msg.msg_type));
  
  	return msg;
  }
  
  static void
  pfm_reset_msgq(pfm_context_t *ctx)
  {
  	ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0;
  	DPRINT(("ctx=%p msgq reset
  ", ctx));
  }
  
  static void *
  pfm_rvmalloc(unsigned long size)
  {
  	void *mem;
  	unsigned long addr;
  
  	size = PAGE_ALIGN(size);

  	mem  = vzalloc(size);

  	if (mem) {
  		//printk("perfmon: CPU%d pfm_rvmalloc(%ld)=%p
  ", smp_processor_id(), size, mem);

  		addr = (unsigned long)mem;
  		while (size > 0) {
  			pfm_reserve_page(addr);
  			addr+=PAGE_SIZE;
  			size-=PAGE_SIZE;
  		}
  	}
  	return mem;
  }
  
  static void
  pfm_rvfree(void *mem, unsigned long size)
  {
  	unsigned long addr;
  
  	if (mem) {
  		DPRINT(("freeing physical buffer @%p size=%lu
  ", mem, size));
  		addr = (unsigned long) mem;
  		while ((long) size > 0) {
  			pfm_unreserve_page(addr);
  			addr+=PAGE_SIZE;
  			size-=PAGE_SIZE;
  		}
  		vfree(mem);
  	}
  	return;
  }
  
  static pfm_context_t *

  pfm_context_alloc(int ctx_flags)

  {
  	pfm_context_t *ctx;
  
  	/* 
  	 * allocate context descriptor 
  	 * must be able to free with interrupts disabled
  	 */

  	ctx = kzalloc(sizeof(pfm_context_t), GFP_KERNEL);

  	if (ctx) {

  		DPRINT(("alloc ctx @%p
  ", ctx));

  
  		/*
  		 * init context protection lock
  		 */
  		spin_lock_init(&ctx->ctx_lock);
  
  		/*
  		 * context is unloaded
  		 */
  		ctx->ctx_state = PFM_CTX_UNLOADED;
  
  		/*
  		 * initialization of context's flags
  		 */
  		ctx->ctx_fl_block       = (ctx_flags & PFM_FL_NOTIFY_BLOCK) ? 1 : 0;
  		ctx->ctx_fl_system      = (ctx_flags & PFM_FL_SYSTEM_WIDE) ? 1: 0;
  		ctx->ctx_fl_no_msg      = (ctx_flags & PFM_FL_OVFL_NO_MSG) ? 1: 0;
  		/*
  		 * will move to set properties
  		 * ctx->ctx_fl_excl_idle   = (ctx_flags & PFM_FL_EXCL_IDLE) ? 1: 0;
  		 */
  
  		/*
  		 * init restart semaphore to locked
  		 */
  		init_completion(&ctx->ctx_restart_done);
  
  		/*
  		 * activation is used in SMP only
  		 */
  		ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
  		SET_LAST_CPU(ctx, -1);
  
  		/*
  		 * initialize notification message queue
  		 */
  		ctx->ctx_msgq_head = ctx->ctx_msgq_tail = 0;
  		init_waitqueue_head(&ctx->ctx_msgq_wait);
  		init_waitqueue_head(&ctx->ctx_zombieq);

  	}
  	return ctx;
  }
  
  static void
  pfm_context_free(pfm_context_t *ctx)
  {
  	if (ctx) {
  		DPRINT(("free ctx @%p
  ", ctx));
  		kfree(ctx);
  	}
  }
  
  static void
  pfm_mask_monitoring(struct task_struct *task)
  {
  	pfm_context_t *ctx = PFM_GET_CTX(task);

  	unsigned long mask, val, ovfl_mask;
  	int i;

  	DPRINT_ovfl(("masking monitoring for [%d]
  ", task_pid_nr(task)));

  
  	ovfl_mask = pmu_conf->ovfl_val;
  	/*
  	 * monitoring can only be masked as a result of a valid
  	 * counter overflow. In UP, it means that the PMU still
  	 * has an owner. Note that the owner can be different
  	 * from the current task. However the PMU state belongs
  	 * to the owner.
  	 * In SMP, a valid overflow only happens when task is
  	 * current. Therefore if we come here, we know that
  	 * the PMU state belongs to the current task, therefore
  	 * we can access the live registers.
  	 *
  	 * So in both cases, the live register contains the owner's
  	 * state. We can ONLY touch the PMU registers and NOT the PSR.
  	 *

  	 * As a consequence to this call, the ctx->th_pmds[] array

  	 * contains stale information which must be ignored
  	 * when context is reloaded AND monitoring is active (see
  	 * pfm_restart).
  	 */
  	mask = ctx->ctx_used_pmds[0];
  	for (i = 0; mask; i++, mask>>=1) {
  		/* skip non used pmds */
  		if ((mask & 0x1) == 0) continue;
  		val = ia64_get_pmd(i);
  
  		if (PMD_IS_COUNTING(i)) {
  			/*
  		 	 * we rebuild the full 64 bit value of the counter
  		 	 */
  			ctx->ctx_pmds[i].val += (val & ovfl_mask);
  		} else {
  			ctx->ctx_pmds[i].val = val;
  		}
  		DPRINT_ovfl(("pmd[%d]=0x%lx hw_pmd=0x%lx
  ",
  			i,
  			ctx->ctx_pmds[i].val,
  			val & ovfl_mask));
  	}
  	/*
  	 * mask monitoring by setting the privilege level to 0
  	 * we cannot use psr.pp/psr.up for this, it is controlled by
  	 * the user
  	 *
  	 * if task is current, modify actual registers, otherwise modify
  	 * thread save state, i.e., what will be restored in pfm_load_regs()
  	 */
  	mask = ctx->ctx_used_monitors[0] >> PMU_FIRST_COUNTER;
  	for(i= PMU_FIRST_COUNTER; mask; i++, mask>>=1) {
  		if ((mask & 0x1) == 0UL) continue;

  		ia64_set_pmc(i, ctx->th_pmcs[i] & ~0xfUL);
  		ctx->th_pmcs[i] &= ~0xfUL;
  		DPRINT_ovfl(("pmc[%d]=0x%lx
  ", i, ctx->th_pmcs[i]));

  	}
  	/*
  	 * make all of this visible
  	 */
  	ia64_srlz_d();
  }
  
  /*
   * must always be done with task == current
   *
   * context must be in MASKED state when calling
   */
  static void
  pfm_restore_monitoring(struct task_struct *task)
  {
  	pfm_context_t *ctx = PFM_GET_CTX(task);

  	unsigned long mask, ovfl_mask;
  	unsigned long psr, val;
  	int i, is_system;
  
  	is_system = ctx->ctx_fl_system;
  	ovfl_mask = pmu_conf->ovfl_val;
  
  	if (task != current) {

  		printk(KERN_ERR "perfmon.%d: invalid task[%d] current[%d]
  ", __LINE__, task_pid_nr(task), task_pid_nr(current));

  		return;
  	}
  	if (ctx->ctx_state != PFM_CTX_MASKED) {
  		printk(KERN_ERR "perfmon.%d: task[%d] current[%d] invalid state=%d
  ", __LINE__,

  			task_pid_nr(task), task_pid_nr(current), ctx->ctx_state);

  		return;
  	}
  	psr = pfm_get_psr();
  	/*
  	 * monitoring is masked via the PMC.
  	 * As we restore their value, we do not want each counter to
  	 * restart right away. We stop monitoring using the PSR,
  	 * restore the PMC (and PMD) and then re-establish the psr
  	 * as it was. Note that there can be no pending overflow at
  	 * this point, because monitoring was MASKED.
  	 *
  	 * system-wide session are pinned and self-monitoring
  	 */
  	if (is_system && (PFM_CPUINFO_GET() & PFM_CPUINFO_DCR_PP)) {
  		/* disable dcr pp */
  		ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) & ~IA64_DCR_PP);
  		pfm_clear_psr_pp();
  	} else {
  		pfm_clear_psr_up();
  	}
  	/*
  	 * first, we restore the PMD
  	 */
  	mask = ctx->ctx_used_pmds[0];
  	for (i = 0; mask; i++, mask>>=1) {
  		/* skip non used pmds */
  		if ((mask & 0x1) == 0) continue;
  
  		if (PMD_IS_COUNTING(i)) {
  			/*
  			 * we split the 64bit value according to
  			 * counter width
  			 */
  			val = ctx->ctx_pmds[i].val & ovfl_mask;
  			ctx->ctx_pmds[i].val &= ~ovfl_mask;
  		} else {
  			val = ctx->ctx_pmds[i].val;
  		}
  		ia64_set_pmd(i, val);
  
  		DPRINT(("pmd[%d]=0x%lx hw_pmd=0x%lx
  ",
  			i,
  			ctx->ctx_pmds[i].val,
  			val));
  	}
  	/*
  	 * restore the PMCs
  	 */
  	mask = ctx->ctx_used_monitors[0] >> PMU_FIRST_COUNTER;
  	for(i= PMU_FIRST_COUNTER; mask; i++, mask>>=1) {
  		if ((mask & 0x1) == 0UL) continue;

  		ctx->th_pmcs[i] = ctx->ctx_pmcs[i];
  		ia64_set_pmc(i, ctx->th_pmcs[i]);

  		DPRINT(("[%d] pmc[%d]=0x%lx
  ",
  					task_pid_nr(task), i, ctx->th_pmcs[i]));

  	}
  	ia64_srlz_d();
  
  	/*
  	 * must restore DBR/IBR because could be modified while masked
  	 * XXX: need to optimize 
  	 */
  	if (ctx->ctx_fl_using_dbreg) {
  		pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
  		pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
  	}
  
  	/*
  	 * now restore PSR
  	 */
  	if (is_system && (PFM_CPUINFO_GET() & PFM_CPUINFO_DCR_PP)) {
  		/* enable dcr pp */
  		ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) | IA64_DCR_PP);
  		ia64_srlz_i();
  	}
  	pfm_set_psr_l(psr);
  }
  
  static inline void
  pfm_save_pmds(unsigned long *pmds, unsigned long mask)
  {
  	int i;
  
  	ia64_srlz_d();
  
  	for (i=0; mask; i++, mask>>=1) {
  		if (mask & 0x1) pmds[i] = ia64_get_pmd(i);
  	}
  }
  
  /*
   * reload from thread state (used for ctxw only)
   */
  static inline void
  pfm_restore_pmds(unsigned long *pmds, unsigned long mask)
  {
  	int i;
  	unsigned long val, ovfl_val = pmu_conf->ovfl_val;
  
  	for (i=0; mask; i++, mask>>=1) {
  		if ((mask & 0x1) == 0) continue;
  		val = PMD_IS_COUNTING(i) ? pmds[i] & ovfl_val : pmds[i];
  		ia64_set_pmd(i, val);
  	}
  	ia64_srlz_d();
  }
  
  /*
   * propagate PMD from context to thread-state
   */
  static inline void
  pfm_copy_pmds(struct task_struct *task, pfm_context_t *ctx)
  {

  	unsigned long ovfl_val = pmu_conf->ovfl_val;
  	unsigned long mask = ctx->ctx_all_pmds[0];
  	unsigned long val;
  	int i;
  
  	DPRINT(("mask=0x%lx
  ", mask));
  
  	for (i=0; mask; i++, mask>>=1) {
  
  		val = ctx->ctx_pmds[i].val;
  
  		/*
  		 * We break up the 64 bit value into 2 pieces
  		 * the lower bits go to the machine state in the
  		 * thread (will be reloaded on ctxsw in).
  		 * The upper part stays in the soft-counter.
  		 */
  		if (PMD_IS_COUNTING(i)) {
  			ctx->ctx_pmds[i].val = val & ~ovfl_val;
  			 val &= ovfl_val;
  		}

  		ctx->th_pmds[i] = val;

  
  		DPRINT(("pmd[%d]=0x%lx soft_val=0x%lx
  ",
  			i,

  			ctx->th_pmds[i],

  			ctx->ctx_pmds[i].val));
  	}
  }
  
  /*
   * propagate PMC from context to thread-state
   */
  static inline void
  pfm_copy_pmcs(struct task_struct *task, pfm_context_t *ctx)
  {

  	unsigned long mask = ctx->ctx_all_pmcs[0];
  	int i;
  
  	DPRINT(("mask=0x%lx
  ", mask));
  
  	for (i=0; mask; i++, mask>>=1) {
  		/* masking 0 with ovfl_val yields 0 */

  		ctx->th_pmcs[i] = ctx->ctx_pmcs[i];
  		DPRINT(("pmc[%d]=0x%lx
  ", i, ctx->th_pmcs[i]));

  	}
  }
  
  
  
  static inline void
  pfm_restore_pmcs(unsigned long *pmcs, unsigned long mask)
  {
  	int i;
  
  	for (i=0; mask; i++, mask>>=1) {
  		if ((mask & 0x1) == 0) continue;
  		ia64_set_pmc(i, pmcs[i]);
  	}
  	ia64_srlz_d();
  }
  
  static inline int
  pfm_uuid_cmp(pfm_uuid_t a, pfm_uuid_t b)
  {
  	return memcmp(a, b, sizeof(pfm_uuid_t));
  }
  
  static inline int
  pfm_buf_fmt_exit(pfm_buffer_fmt_t *fmt, struct task_struct *task, void *buf, struct pt_regs *regs)
  {
  	int ret = 0;
  	if (fmt->fmt_exit) ret = (*fmt->fmt_exit)(task, buf, regs);
  	return ret;
  }
  
  static inline int
  pfm_buf_fmt_getsize(pfm_buffer_fmt_t *fmt, struct task_struct *task, unsigned int flags, int cpu, void *arg, unsigned long *size)
  {
  	int ret = 0;
  	if (fmt->fmt_getsize) ret = (*fmt->fmt_getsize)(task, flags, cpu, arg, size);
  	return ret;
  }
  
  
  static inline int
  pfm_buf_fmt_validate(pfm_buffer_fmt_t *fmt, struct task_struct *task, unsigned int flags,
  		     int cpu, void *arg)
  {
  	int ret = 0;
  	if (fmt->fmt_validate) ret = (*fmt->fmt_validate)(task, flags, cpu, arg);
  	return ret;
  }
  
  static inline int
  pfm_buf_fmt_init(pfm_buffer_fmt_t *fmt, struct task_struct *task, void *buf, unsigned int flags,
  		     int cpu, void *arg)
  {
  	int ret = 0;
  	if (fmt->fmt_init) ret = (*fmt->fmt_init)(task, buf, flags, cpu, arg);
  	return ret;
  }
  
  static inline int
  pfm_buf_fmt_restart(pfm_buffer_fmt_t *fmt, struct task_struct *task, pfm_ovfl_ctrl_t *ctrl, void *buf, struct pt_regs *regs)
  {
  	int ret = 0;
  	if (fmt->fmt_restart) ret = (*fmt->fmt_restart)(task, ctrl, buf, regs);
  	return ret;
  }
  
  static inline int
  pfm_buf_fmt_restart_active(pfm_buffer_fmt_t *fmt, struct task_struct *task, pfm_ovfl_ctrl_t *ctrl, void *buf, struct pt_regs *regs)
  {
  	int ret = 0;
  	if (fmt->fmt_restart_active) ret = (*fmt->fmt_restart_active)(task, ctrl, buf, regs);
  	return ret;
  }
  
  static pfm_buffer_fmt_t *
  __pfm_find_buffer_fmt(pfm_uuid_t uuid)
  {
  	struct list_head * pos;
  	pfm_buffer_fmt_t * entry;
  
  	list_for_each(pos, &pfm_buffer_fmt_list) {
  		entry = list_entry(pos, pfm_buffer_fmt_t, fmt_list);
  		if (pfm_uuid_cmp(uuid, entry->fmt_uuid) == 0)
  			return entry;
  	}
  	return NULL;
  }
   
  /*
   * find a buffer format based on its uuid
   */
  static pfm_buffer_fmt_t *
  pfm_find_buffer_fmt(pfm_uuid_t uuid)
  {
  	pfm_buffer_fmt_t * fmt;
  	spin_lock(&pfm_buffer_fmt_lock);
  	fmt = __pfm_find_buffer_fmt(uuid);
  	spin_unlock(&pfm_buffer_fmt_lock);
  	return fmt;
  }
   
  int
  pfm_register_buffer_fmt(pfm_buffer_fmt_t *fmt)
  {
  	int ret = 0;
  
  	/* some sanity checks */
  	if (fmt == NULL || fmt->fmt_name == NULL) return -EINVAL;
  
  	/* we need at least a handler */
  	if (fmt->fmt_handler == NULL) return -EINVAL;
  
  	/*
  	 * XXX: need check validity of fmt_arg_size
  	 */
  
  	spin_lock(&pfm_buffer_fmt_lock);
  
  	if (__pfm_find_buffer_fmt(fmt->fmt_uuid)) {
  		printk(KERN_ERR "perfmon: duplicate sampling format: %s
  ", fmt->fmt_name);
  		ret = -EBUSY;
  		goto out;
  	} 
  	list_add(&fmt->fmt_list, &pfm_buffer_fmt_list);
  	printk(KERN_INFO "perfmon: added sampling format %s
  ", fmt->fmt_name);
  
  out:
  	spin_unlock(&pfm_buffer_fmt_lock);
   	return ret;
  }
  EXPORT_SYMBOL(pfm_register_buffer_fmt);
  
  int
  pfm_unregister_buffer_fmt(pfm_uuid_t uuid)
  {
  	pfm_buffer_fmt_t *fmt;
  	int ret = 0;
  
  	spin_lock(&pfm_buffer_fmt_lock);
  
  	fmt = __pfm_find_buffer_fmt(uuid);
  	if (!fmt) {
  		printk(KERN_ERR "perfmon: cannot unregister format, not found
  ");
  		ret = -EINVAL;
  		goto out;
  	}
  	list_del_init(&fmt->fmt_list);
  	printk(KERN_INFO "perfmon: removed sampling format: %s
  ", fmt->fmt_name);
  
  out:
  	spin_unlock(&pfm_buffer_fmt_lock);
  	return ret;
  
  }
  EXPORT_SYMBOL(pfm_unregister_buffer_fmt);

  extern void update_pal_halt_status(int);

  static int
  pfm_reserve_session(struct task_struct *task, int is_syswide, unsigned int cpu)
  {
  	unsigned long flags;
  	/*

  	 * validity checks on cpu_mask have been done upstream

  	 */
  	LOCK_PFS(flags);
  
  	DPRINT(("in sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d cpu=%u
  ",
  		pfm_sessions.pfs_sys_sessions,
  		pfm_sessions.pfs_task_sessions,
  		pfm_sessions.pfs_sys_use_dbregs,
  		is_syswide,
  		cpu));
  
  	if (is_syswide) {
  		/*
  		 * cannot mix system wide and per-task sessions
  		 */
  		if (pfm_sessions.pfs_task_sessions > 0UL) {
  			DPRINT(("system wide not possible, %u conflicting task_sessions
  ",
  			  	pfm_sessions.pfs_task_sessions));
  			goto abort;
  		}
  
  		if (pfm_sessions.pfs_sys_session[cpu]) goto error_conflict;
  
  		DPRINT(("reserving system wide session on CPU%u currently on CPU%u
  ", cpu, smp_processor_id()));
  
  		pfm_sessions.pfs_sys_session[cpu] = task;
  
  		pfm_sessions.pfs_sys_sessions++ ;
  
  	} else {
  		if (pfm_sessions.pfs_sys_sessions) goto abort;
  		pfm_sessions.pfs_task_sessions++;
  	}
  
  	DPRINT(("out sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d cpu=%u
  ",
  		pfm_sessions.pfs_sys_sessions,
  		pfm_sessions.pfs_task_sessions,
  		pfm_sessions.pfs_sys_use_dbregs,
  		is_syswide,
  		cpu));

  	/*
  	 * disable default_idle() to go to PAL_HALT
  	 */
  	update_pal_halt_status(0);

  	UNLOCK_PFS(flags);
  
  	return 0;
  
  error_conflict:
  	DPRINT(("system wide not possible, conflicting session [%d] on CPU%d
  ",

    		task_pid_nr(pfm_sessions.pfs_sys_session[cpu]),

  		cpu));

  abort:
  	UNLOCK_PFS(flags);
  
  	return -EBUSY;
  
  }
  
  static int
  pfm_unreserve_session(pfm_context_t *ctx, int is_syswide, unsigned int cpu)
  {
  	unsigned long flags;
  	/*

  	 * validity checks on cpu_mask have been done upstream

  	 */
  	LOCK_PFS(flags);
  
  	DPRINT(("in sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d cpu=%u
  ",
  		pfm_sessions.pfs_sys_sessions,
  		pfm_sessions.pfs_task_sessions,
  		pfm_sessions.pfs_sys_use_dbregs,
  		is_syswide,
  		cpu));
  
  
  	if (is_syswide) {
  		pfm_sessions.pfs_sys_session[cpu] = NULL;
  		/*
  		 * would not work with perfmon+more than one bit in cpu_mask
  		 */
  		if (ctx && ctx->ctx_fl_using_dbreg) {
  			if (pfm_sessions.pfs_sys_use_dbregs == 0) {
  				printk(KERN_ERR "perfmon: invalid release for ctx %p sys_use_dbregs=0
  ", ctx);
  			} else {
  				pfm_sessions.pfs_sys_use_dbregs--;
  			}
  		}
  		pfm_sessions.pfs_sys_sessions--;
  	} else {
  		pfm_sessions.pfs_task_sessions--;
  	}
  	DPRINT(("out sys_sessions=%u task_sessions=%u dbregs=%u syswide=%d cpu=%u
  ",
  		pfm_sessions.pfs_sys_sessions,
  		pfm_sessions.pfs_task_sessions,
  		pfm_sessions.pfs_sys_use_dbregs,
  		is_syswide,
  		cpu));

  	/*
  	 * if possible, enable default_idle() to go into PAL_HALT
  	 */
  	if (pfm_sessions.pfs_task_sessions == 0 && pfm_sessions.pfs_sys_sessions == 0)
  		update_pal_halt_status(1);

  	UNLOCK_PFS(flags);
  
  	return 0;
  }
  
  /*
   * removes virtual mapping of the sampling buffer.
   * IMPORTANT: cannot be called with interrupts disable, e.g. inside
   * a PROTECT_CTX() section.
   */
  static int
  pfm_remove_smpl_mapping(struct task_struct *task, void *vaddr, unsigned long size)
  {
  	int r;
  
  	/* sanity checks */
  	if (task->mm == NULL || size == 0UL || vaddr == NULL) {

  		printk(KERN_ERR "perfmon: pfm_remove_smpl_mapping [%d] invalid context mm=%p
  ", task_pid_nr(task), task->mm);

  		return -EINVAL;
  	}
  
  	DPRINT(("smpl_vaddr=%p size=%lu
  ", vaddr, size));
  
  	/*
  	 * does the actual unmapping
  	 */
  	down_write(&task->mm->mmap_sem);
  
  	DPRINT(("down_write done smpl_vaddr=%p size=%lu
  ", vaddr, size));
  
  	r = pfm_do_munmap(task->mm, (unsigned long)vaddr, size, 0);
  
  	up_write(&task->mm->mmap_sem);
  	if (r !=0) {

  		printk(KERN_ERR "perfmon: [%d] unable to unmap sampling buffer @%p size=%lu
  ", task_pid_nr(task), vaddr, size);

  	}
  
  	DPRINT(("do_unmap(%p, %lu)=%d
  ", vaddr, size, r));
  
  	return 0;
  }
  
  /*
   * free actual physical storage used by sampling buffer
   */
  #if 0
  static int
  pfm_free_smpl_buffer(pfm_context_t *ctx)
  {
  	pfm_buffer_fmt_t *fmt;
  
  	if (ctx->ctx_smpl_hdr == NULL) goto invalid_free;
  
  	/*
  	 * we won't use the buffer format anymore
  	 */
  	fmt = ctx->ctx_buf_fmt;
  
  	DPRINT(("sampling buffer @%p size %lu vaddr=%p
  ",
  		ctx->ctx_smpl_hdr,
  		ctx->ctx_smpl_size,
  		ctx->ctx_smpl_vaddr));
  
  	pfm_buf_fmt_exit(fmt, current, NULL, NULL);
  
  	/*
  	 * free the buffer
  	 */
  	pfm_rvfree(ctx->ctx_smpl_hdr, ctx->ctx_smpl_size);
  
  	ctx->ctx_smpl_hdr  = NULL;
  	ctx->ctx_smpl_size = 0UL;
  
  	return 0;
  
  invalid_free:

  	printk(KERN_ERR "perfmon: pfm_free_smpl_buffer [%d] no buffer
  ", task_pid_nr(current));

  	return -EINVAL;
  }
  #endif
  
  static inline void
  pfm_exit_smpl_buffer(pfm_buffer_fmt_t *fmt)
  {
  	if (fmt == NULL) return;
  
  	pfm_buf_fmt_exit(fmt, current, NULL, NULL);
  
  }
  
  /*
   * pfmfs should _never_ be mounted by userland - too much of security hassle,
   * no real gain from having the whole whorehouse mounted. So we don't need
   * any operations on the root directory. However, we need a non-trivial
   * d_name - pfm: will go nicely and kill the special-casing in procfs.
   */

  static struct vfsmount *pfmfs_mnt __read_mostly;

  
  static int __init
  init_pfm_fs(void)
  {
  	int err = register_filesystem(&pfm_fs_type);
  	if (!err) {
  		pfmfs_mnt = kern_mount(&pfm_fs_type);
  		err = PTR_ERR(pfmfs_mnt);
  		if (IS_ERR(pfmfs_mnt))
  			unregister_filesystem(&pfm_fs_type);
  		else
  			err = 0;
  	}
  	return err;
  }

  static ssize_t
  pfm_read(struct file *filp, char __user *buf, size_t size, loff_t *ppos)
  {
  	pfm_context_t *ctx;
  	pfm_msg_t *msg;
  	ssize_t ret;
  	unsigned long flags;
    	DECLARE_WAITQUEUE(wait, current);
  	if (PFM_IS_FILE(filp) == 0) {

  		printk(KERN_ERR "perfmon: pfm_poll: bad magic [%d]
  ", task_pid_nr(current));

  		return -EINVAL;
  	}

  	ctx = filp->private_data;

  	if (ctx == NULL) {

  		printk(KERN_ERR "perfmon: pfm_read: NULL ctx [%d]
  ", task_pid_nr(current));

  		return -EINVAL;
  	}
  
  	/*
  	 * check even when there is no message
  	 */
  	if (size < sizeof(pfm_msg_t)) {
  		DPRINT(("message is too small ctx=%p (>=%ld)
  ", ctx, sizeof(pfm_msg_t)));
  		return -EINVAL;
  	}
  
  	PROTECT_CTX(ctx, flags);
  
    	/*
  	 * put ourselves on the wait queue
  	 */
    	add_wait_queue(&ctx->ctx_msgq_wait, &wait);
  
  
    	for(;;) {
  		/*
  		 * check wait queue
  		 */
  
    		set_current_state(TASK_INTERRUPTIBLE);
  
  		DPRINT(("head=%d tail=%d
  ", ctx->ctx_msgq_head, ctx->ctx_msgq_tail));
  
  		ret = 0;
  		if(PFM_CTXQ_EMPTY(ctx) == 0) break;
  
  		UNPROTECT_CTX(ctx, flags);
  
  		/*
  		 * check non-blocking read
  		 */
        		ret = -EAGAIN;
  		if(filp->f_flags & O_NONBLOCK) break;
  
  		/*
  		 * check pending signals
  		 */
  		if(signal_pending(current)) {
  			ret = -EINTR;
  			break;
  		}
        		/*
  		 * no message, so wait
  		 */
        		schedule();
  
  		PROTECT_CTX(ctx, flags);
  	}

  	DPRINT(("[%d] back to running ret=%ld
  ", task_pid_nr(current), ret));

    	set_current_state(TASK_RUNNING);
  	remove_wait_queue(&ctx->ctx_msgq_wait, &wait);
  
  	if (ret < 0) goto abort;
  
  	ret = -EINVAL;
  	msg = pfm_get_next_msg(ctx);
  	if (msg == NULL) {

  		printk(KERN_ERR "perfmon: pfm_read no msg for ctx=%p [%d]
  ", ctx, task_pid_nr(current));

  		goto abort_locked;
  	}

  	DPRINT(("fd=%d type=%d
  ", msg->pfm_gen_msg.msg_ctx_fd, msg->pfm_gen_msg.msg_type));

  
  	ret = -EFAULT;
    	if(copy_to_user(buf, msg, sizeof(pfm_msg_t)) == 0) ret = sizeof(pfm_msg_t);
  
  abort_locked:
  	UNPROTECT_CTX(ctx, flags);
  abort:
  	return ret;
  }
  
  static ssize_t
  pfm_write(struct file *file, const char __user *ubuf,
  			  size_t size, loff_t *ppos)
  {
  	DPRINT(("pfm_write called
  "));
  	return -EINVAL;
  }
  
  static unsigned int
  pfm_poll(struct file *filp, poll_table * wait)
  {
  	pfm_context_t *ctx;
  	unsigned long flags;
  	unsigned int mask = 0;
  
  	if (PFM_IS_FILE(filp) == 0) {

  		printk(KERN_ERR "perfmon: pfm_poll: bad magic [%d]
  ", task_pid_nr(current));

  		return 0;
  	}

  	ctx = filp->private_data;

  	if (ctx == NULL) {

  		printk(KERN_ERR "perfmon: pfm_poll: NULL ctx [%d]
  ", task_pid_nr(current));

  		return 0;
  	}
  
  
  	DPRINT(("pfm_poll ctx_fd=%d before poll_wait
  ", ctx->ctx_fd));
  
  	poll_wait(filp, &ctx->ctx_msgq_wait, wait);
  
  	PROTECT_CTX(ctx, flags);
  
  	if (PFM_CTXQ_EMPTY(ctx) == 0)
  		mask =  POLLIN | POLLRDNORM;
  
  	UNPROTECT_CTX(ctx, flags);
  
  	DPRINT(("pfm_poll ctx_fd=%d mask=0x%x
  ", ctx->ctx_fd, mask));
  
  	return mask;
  }

  static long
  pfm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

  {
  	DPRINT(("pfm_ioctl called
  "));
  	return -EINVAL;
  }
  
  /*
   * interrupt cannot be masked when coming here
   */
  static inline int
  pfm_do_fasync(int fd, struct file *filp, pfm_context_t *ctx, int on)
  {
  	int ret;
  
  	ret = fasync_helper (fd, filp, on, &ctx->ctx_async_queue);
  
  	DPRINT(("pfm_fasync called by [%d] on ctx_fd=%d on=%d async_queue=%p ret=%d
  ",

  		task_pid_nr(current),

  		fd,
  		on,
  		ctx->ctx_async_queue, ret));
  
  	return ret;
  }
  
  static int
  pfm_fasync(int fd, struct file *filp, int on)
  {
  	pfm_context_t *ctx;
  	int ret;
  
  	if (PFM_IS_FILE(filp) == 0) {

  		printk(KERN_ERR "perfmon: pfm_fasync bad magic [%d]
  ", task_pid_nr(current));

  		return -EBADF;
  	}

  	ctx = filp->private_data;

  	if (ctx == NULL) {

  		printk(KERN_ERR "perfmon: pfm_fasync NULL ctx [%d]
  ", task_pid_nr(current));

  		return -EBADF;
  	}
  	/*
  	 * we cannot mask interrupts during this call because this may
  	 * may go to sleep if memory is not readily avalaible.
  	 *
  	 * We are protected from the conetxt disappearing by the get_fd()/put_fd()
  	 * done in caller. Serialization of this function is ensured by caller.
  	 */
  	ret = pfm_do_fasync(fd, filp, ctx, on);
  
  
  	DPRINT(("pfm_fasync called on ctx_fd=%d on=%d async_queue=%p ret=%d
  ",
  		fd,
  		on,
  		ctx->ctx_async_queue, ret));
  
  	return ret;
  }
  
  #ifdef CONFIG_SMP
  /*
   * this function is exclusively called from pfm_close().
   * The context is not protected at that time, nor are interrupts
   * on the remote CPU. That's necessary to avoid deadlocks.
   */
  static void
  pfm_syswide_force_stop(void *info)
  {
  	pfm_context_t   *ctx = (pfm_context_t *)info;

  	struct pt_regs *regs = task_pt_regs(current);

  	struct task_struct *owner;
  	unsigned long flags;
  	int ret;
  
  	if (ctx->ctx_cpu != smp_processor_id()) {
  		printk(KERN_ERR "perfmon: pfm_syswide_force_stop for CPU%d  but on CPU%d
  ",
  			ctx->ctx_cpu,
  			smp_processor_id());
  		return;
  	}
  	owner = GET_PMU_OWNER();
  	if (owner != ctx->ctx_task) {
  		printk(KERN_ERR "perfmon: pfm_syswide_force_stop CPU%d unexpected owner [%d] instead of [%d]
  ",
  			smp_processor_id(),

  			task_pid_nr(owner), task_pid_nr(ctx->ctx_task));

  		return;
  	}
  	if (GET_PMU_CTX() != ctx) {
  		printk(KERN_ERR "perfmon: pfm_syswide_force_stop CPU%d unexpected ctx %p instead of %p
  ",
  			smp_processor_id(),
  			GET_PMU_CTX(), ctx);
  		return;
  	}

  	DPRINT(("on CPU%d forcing system wide stop for [%d]
  ", smp_processor_id(), task_pid_nr(ctx->ctx_task)));

  	/*
  	 * the context is already protected in pfm_close(), we simply
  	 * need to mask interrupts to avoid a PMU interrupt race on
  	 * this CPU
  	 */
  	local_irq_save(flags);
  
  	ret = pfm_context_unload(ctx, NULL, 0, regs);
  	if (ret) {
  		DPRINT(("context_unload returned %d
  ", ret));
  	}
  
  	/*
  	 * unmask interrupts, PMU interrupts are now spurious here
  	 */
  	local_irq_restore(flags);
  }
  
  static void
  pfm_syswide_cleanup_other_cpu(pfm_context_t *ctx)
  {
  	int ret;
  
  	DPRINT(("calling CPU%d for cleanup
  ", ctx->ctx_cpu));

  	ret = smp_call_function_single(ctx->ctx_cpu, pfm_syswide_force_stop, ctx, 1);

  	DPRINT(("called CPU%d for cleanup ret=%d
  ", ctx->ctx_cpu, ret));
  }
  #endif /* CONFIG_SMP */
  
  /*
   * called for each close(). Partially free resources.
   * When caller is self-monitoring, the context is unloaded.
   */
  static int

  pfm_flush(struct file *filp, fl_owner_t id)

  {
  	pfm_context_t *ctx;
  	struct task_struct *task;
  	struct pt_regs *regs;
  	unsigned long flags;
  	unsigned long smpl_buf_size = 0UL;
  	void *smpl_buf_vaddr = NULL;
  	int state, is_system;
  
  	if (PFM_IS_FILE(filp) == 0) {
  		DPRINT(("bad magic for
  "));
  		return -EBADF;
  	}

  	ctx = filp->private_data;

  	if (ctx == NULL) {

  		printk(KERN_ERR "perfmon: pfm_flush: NULL ctx [%d]
  ", task_pid_nr(current));

  		return -EBADF;
  	}
  
  	/*
  	 * remove our file from the async queue, if we use this mode.
  	 * This can be done without the context being protected. We come

  	 * here when the context has become unreachable by other tasks.

  	 *
  	 * We may still have active monitoring at this point and we may
  	 * end up in pfm_overflow_handler(). However, fasync_helper()
  	 * operates with interrupts disabled and it cleans up the
  	 * queue. If the PMU handler is called prior to entering
  	 * fasync_helper() then it will send a signal. If it is
  	 * invoked after, it will find an empty queue and no
  	 * signal will be sent. In both case, we are safe
  	 */

  	PROTECT_CTX(ctx, flags);
  
  	state     = ctx->ctx_state;
  	is_system = ctx->ctx_fl_system;
  
  	task = PFM_CTX_TASK(ctx);

  	regs = task_pt_regs(task);

  
  	DPRINT(("ctx_state=%d is_current=%d
  ",
  		state,
  		task == current ? 1 : 0));
  
  	/*
  	 * if state == UNLOADED, then task is NULL
  	 */
  
  	/*
  	 * we must stop and unload because we are losing access to the context.
  	 */
  	if (task == current) {
  #ifdef CONFIG_SMP
  		/*
  		 * the task IS the owner but it migrated to another CPU: that's bad
  		 * but we must handle this cleanly. Unfortunately, the kernel does
  		 * not provide a mechanism to block migration (while the context is loaded).
  		 *
  		 * We need to release the resource on the ORIGINAL cpu.
  		 */
  		if (is_system && ctx->ctx_cpu != smp_processor_id()) {
  
  			DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  			/*
  			 * keep context protected but unmask interrupt for IPI
  			 */
  			local_irq_restore(flags);
  
  			pfm_syswide_cleanup_other_cpu(ctx);
  
  			/*
  			 * restore interrupt masking
  			 */
  			local_irq_save(flags);
  
  			/*
  			 * context is unloaded at this point
  			 */
  		} else
  #endif /* CONFIG_SMP */
  		{
  
  			DPRINT(("forcing unload
  "));
  			/*
  		 	* stop and unload, returning with state UNLOADED
  		 	* and session unreserved.
  		 	*/
  			pfm_context_unload(ctx, NULL, 0, regs);
  
  			DPRINT(("ctx_state=%d
  ", ctx->ctx_state));
  		}
  	}
  
  	/*
  	 * remove virtual mapping, if any, for the calling task.
  	 * cannot reset ctx field until last user is calling close().
  	 *
  	 * ctx_smpl_vaddr must never be cleared because it is needed
  	 * by every task with access to the context
  	 *
  	 * When called from do_exit(), the mm context is gone already, therefore
  	 * mm is NULL, i.e., the VMA is already gone  and we do not have to
  	 * do anything here
  	 */
  	if (ctx->ctx_smpl_vaddr && current->mm) {
  		smpl_buf_vaddr = ctx->ctx_smpl_vaddr;
  		smpl_buf_size  = ctx->ctx_smpl_size;
  	}
  
  	UNPROTECT_CTX(ctx, flags);
  
  	/*
  	 * if there was a mapping, then we systematically remove it
  	 * at this point. Cannot be done inside critical section
  	 * because some VM function reenables interrupts.
  	 *
  	 */
  	if (smpl_buf_vaddr) pfm_remove_smpl_mapping(current, smpl_buf_vaddr, smpl_buf_size);
  
  	return 0;
  }
  /*
   * called either on explicit close() or from exit_files(). 
   * Only the LAST user of the file gets to this point, i.e., it is
   * called only ONCE.
   *
   * IMPORTANT: we get called ONLY when the refcnt on the file gets to zero 
   * (fput()),i.e, last task to access the file. Nobody else can access the 
   * file at this point.
   *
   * When called from exit_files(), the VMA has been freed because exit_mm()
   * is executed before exit_files().
   *
   * When called from exit_files(), the current task is not yet ZOMBIE but we
   * flush the PMU state to the context. 
   */
  static int
  pfm_close(struct inode *inode, struct file *filp)
  {
  	pfm_context_t *ctx;
  	struct task_struct *task;
  	struct pt_regs *regs;
    	DECLARE_WAITQUEUE(wait, current);
  	unsigned long flags;
  	unsigned long smpl_buf_size = 0UL;
  	void *smpl_buf_addr = NULL;
  	int free_possible = 1;
  	int state, is_system;
  
  	DPRINT(("pfm_close called private=%p
  ", filp->private_data));
  
  	if (PFM_IS_FILE(filp) == 0) {
  		DPRINT(("bad magic
  "));
  		return -EBADF;
  	}
  	

  	ctx = filp->private_data;

  	if (ctx == NULL) {

  		printk(KERN_ERR "perfmon: pfm_close: NULL ctx [%d]
  ", task_pid_nr(current));

  		return -EBADF;
  	}
  
  	PROTECT_CTX(ctx, flags);
  
  	state     = ctx->ctx_state;
  	is_system = ctx->ctx_fl_system;
  
  	task = PFM_CTX_TASK(ctx);

  	regs = task_pt_regs(task);

  
  	DPRINT(("ctx_state=%d is_current=%d
  ", 
  		state,
  		task == current ? 1 : 0));
  
  	/*
  	 * if task == current, then pfm_flush() unloaded the context
  	 */
  	if (state == PFM_CTX_UNLOADED) goto doit;
  
  	/*
  	 * context is loaded/masked and task != current, we need to
  	 * either force an unload or go zombie
  	 */
  
  	/*
  	 * The task is currently blocked or will block after an overflow.
  	 * we must force it to wakeup to get out of the
  	 * MASKED state and transition to the unloaded state by itself.
  	 *
  	 * This situation is only possible for per-task mode
  	 */
  	if (state == PFM_CTX_MASKED && CTX_OVFL_NOBLOCK(ctx) == 0) {
  
  		/*
  		 * set a "partial" zombie state to be checked
  		 * upon return from down() in pfm_handle_work().
  		 *
  		 * We cannot use the ZOMBIE state, because it is checked
  		 * by pfm_load_regs() which is called upon wakeup from down().
  		 * In such case, it would free the context and then we would
  		 * return to pfm_handle_work() which would access the
  		 * stale context. Instead, we set a flag invisible to pfm_load_regs()
  		 * but visible to pfm_handle_work().
  		 *
  		 * For some window of time, we have a zombie context with
  		 * ctx_state = MASKED  and not ZOMBIE
  		 */
  		ctx->ctx_fl_going_zombie = 1;
  
  		/*
  		 * force task to wake up from MASKED state
  		 */

  		complete(&ctx->ctx_restart_done);

  
  		DPRINT(("waking up ctx_state=%d
  ", state));
  
  		/*
  		 * put ourself to sleep waiting for the other
  		 * task to report completion
  		 *
  		 * the context is protected by mutex, therefore there
  		 * is no risk of being notified of completion before
  		 * begin actually on the waitq.
  		 */
    		set_current_state(TASK_INTERRUPTIBLE);
    		add_wait_queue(&ctx->ctx_zombieq, &wait);
  
  		UNPROTECT_CTX(ctx, flags);
  
  		/*
  		 * XXX: check for signals :
  		 * 	- ok for explicit close
  		 * 	- not ok when coming from exit_files()
  		 */
        		schedule();
  
  
  		PROTECT_CTX(ctx, flags);
  
  
  		remove_wait_queue(&ctx->ctx_zombieq, &wait);
    		set_current_state(TASK_RUNNING);
  
  		/*
  		 * context is unloaded at this point
  		 */
  		DPRINT(("after zombie wakeup ctx_state=%d for
  ", state));
  	}
  	else if (task != current) {
  #ifdef CONFIG_SMP
  		/*
  	 	 * switch context to zombie state
  	 	 */
  		ctx->ctx_state = PFM_CTX_ZOMBIE;

  		DPRINT(("zombie ctx for [%d]
  ", task_pid_nr(task)));

  		/*
  		 * cannot free the context on the spot. deferred until
  		 * the task notices the ZOMBIE state
  		 */
  		free_possible = 0;
  #else
  		pfm_context_unload(ctx, NULL, 0, regs);
  #endif
  	}
  
  doit:
  	/* reload state, may have changed during  opening of critical section */
  	state = ctx->ctx_state;
  
  	/*
  	 * the context is still attached to a task (possibly current)
  	 * we cannot destroy it right now
  	 */
  
  	/*
  	 * we must free the sampling buffer right here because
  	 * we cannot rely on it being cleaned up later by the
  	 * monitored task. It is not possible to free vmalloc'ed
  	 * memory in pfm_load_regs(). Instead, we remove the buffer
  	 * now. should there be subsequent PMU overflow originally
  	 * meant for sampling, the will be converted to spurious
  	 * and that's fine because the monitoring tools is gone anyway.
  	 */
  	if (ctx->ctx_smpl_hdr) {
  		smpl_buf_addr = ctx->ctx_smpl_hdr;
  		smpl_buf_size = ctx->ctx_smpl_size;
  		/* no more sampling */
  		ctx->ctx_smpl_hdr = NULL;
  		ctx->ctx_fl_is_sampling = 0;
  	}
  
  	DPRINT(("ctx_state=%d free_possible=%d addr=%p size=%lu
  ",
  		state,
  		free_possible,
  		smpl_buf_addr,
  		smpl_buf_size));
  
  	if (smpl_buf_addr) pfm_exit_smpl_buffer(ctx->ctx_buf_fmt);
  
  	/*
  	 * UNLOADED that the session has already been unreserved.
  	 */
  	if (state == PFM_CTX_ZOMBIE) {
  		pfm_unreserve_session(ctx, ctx->ctx_fl_system , ctx->ctx_cpu);
  	}
  
  	/*
  	 * disconnect file descriptor from context must be done
  	 * before we unlock.
  	 */
  	filp->private_data = NULL;
  
  	/*

  	 * if we free on the spot, the context is now completely unreachable

  	 * from the callers side. The monitored task side is also cut, so we
  	 * can freely cut.
  	 *
  	 * If we have a deferred free, only the caller side is disconnected.
  	 */
  	UNPROTECT_CTX(ctx, flags);
  
  	/*
  	 * All memory free operations (especially for vmalloc'ed memory)
  	 * MUST be done with interrupts ENABLED.
  	 */
  	if (smpl_buf_addr)  pfm_rvfree(smpl_buf_addr, smpl_buf_size);
  
  	/*
  	 * return the memory used by the context
  	 */
  	if (free_possible) pfm_context_free(ctx);
  
  	return 0;
  }
  
  static int
  pfm_no_open(struct inode *irrelevant, struct file *dontcare)
  {
  	DPRINT(("pfm_no_open called
  "));
  	return -ENXIO;
  }

  static const struct file_operations pfm_file_ops = {

  	.llseek		= no_llseek,
  	.read		= pfm_read,
  	.write		= pfm_write,
  	.poll		= pfm_poll,
  	.unlocked_ioctl = pfm_ioctl,
  	.open		= pfm_no_open,	/* special open code to disallow open via /proc */
  	.fasync		= pfm_fasync,
  	.release	= pfm_close,
  	.flush		= pfm_flush

  };
  
  static int

  pfmfs_delete_dentry(const struct dentry *dentry)

  {
  	return 1;
  }

  static char *pfmfs_dname(struct dentry *dentry, char *buffer, int buflen)
  {
  	return dynamic_dname(dentry, buffer, buflen, "pfm:[%lu]",
  			     dentry->d_inode->i_ino);
  }

  static const struct dentry_operations pfmfs_dentry_operations = {

  	.d_delete = pfmfs_delete_dentry,

  	.d_dname = pfmfs_dname,

  };

  static struct file *
  pfm_alloc_file(pfm_context_t *ctx)

  {

  	struct file *file;
  	struct inode *inode;

  	struct path path;

  	struct qstr this = { .name = "" };

  	/*
  	 * allocate a new inode
  	 */
  	inode = new_inode(pfmfs_mnt->mnt_sb);

  	if (!inode)
  		return ERR_PTR(-ENOMEM);

  
  	DPRINT(("new inode ino=%ld @%p
  ", inode->i_ino, inode));
  
  	inode->i_mode = S_IFCHR|S_IRUGO;

  	inode->i_uid  = current_fsuid();
  	inode->i_gid  = current_fsgid();

  	/*
  	 * allocate a new dcache entry
  	 */

  	path.dentry = d_alloc(pfmfs_mnt->mnt_root, &this);

  	if (!path.dentry) {

  		iput(inode);
  		return ERR_PTR(-ENOMEM);
  	}

  	path.mnt = mntget(pfmfs_mnt);

  	d_add(path.dentry, inode);

  	file = alloc_file(&path, FMODE_READ, &pfm_file_ops);

  	if (!file) {

  		path_put(&path);

  		return ERR_PTR(-ENFILE);
  	}

  	file->f_flags = O_RDONLY;

  	file->private_data = ctx;

  	return file;

  }
  
  static int
  pfm_remap_buffer(struct vm_area_struct *vma, unsigned long buf, unsigned long addr, unsigned long size)
  {
  	DPRINT(("CPU%d buf=0x%lx addr=0x%lx size=%ld
  ", smp_processor_id(), buf, addr, size));
  
  	while (size > 0) {
  		unsigned long pfn = ia64_tpa(buf) >> PAGE_SHIFT;
  
  
  		if (remap_pfn_range(vma, addr, pfn, PAGE_SIZE, PAGE_READONLY))
  			return -ENOMEM;
  
  		addr  += PAGE_SIZE;
  		buf   += PAGE_SIZE;
  		size  -= PAGE_SIZE;
  	}
  	return 0;
  }
  
  /*
   * allocate a sampling buffer and remaps it into the user address space of the task
   */
  static int

  pfm_smpl_buffer_alloc(struct task_struct *task, struct file *filp, pfm_context_t *ctx, unsigned long rsize, void **user_vaddr)

  {
  	struct mm_struct *mm = task->mm;
  	struct vm_area_struct *vma = NULL;
  	unsigned long size;
  	void *smpl_buf;
  
  
  	/*
  	 * the fixed header + requested size and align to page boundary
  	 */
  	size = PAGE_ALIGN(rsize);
  
  	DPRINT(("sampling buffer rsize=%lu size=%lu bytes
  ", rsize, size));
  
  	/*
  	 * check requested size to avoid Denial-of-service attacks
  	 * XXX: may have to refine this test
  	 * Check against address space limit.
  	 *
  	 * if ((mm->total_vm << PAGE_SHIFT) + len> task->rlim[RLIMIT_AS].rlim_cur)
  	 * 	return -ENOMEM;
  	 */

  	if (size > task_rlimit(task, RLIMIT_MEMLOCK))

  		return -ENOMEM;
  
  	/*
  	 * We do the easy to undo allocations first.
   	 *
  	 * pfm_rvmalloc(), clears the buffer, so there is no leak
  	 */
  	smpl_buf = pfm_rvmalloc(size);
  	if (smpl_buf == NULL) {
  		DPRINT(("Can't allocate sampling buffer
  "));
  		return -ENOMEM;
  	}
  
  	DPRINT(("smpl_buf @%p
  ", smpl_buf));
  
  	/* allocate vma */

  	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);

  	if (!vma) {
  		DPRINT(("Cannot allocate vma
  "));
  		goto error_kmem;
  	}

  	INIT_LIST_HEAD(&vma->anon_vma_chain);

  
  	/*
  	 * partially initialize the vma for the sampling buffer
  	 */
  	vma->vm_mm	     = mm;

  	vma->vm_file	     = filp;

  	vma->vm_flags	     = VM_READ| VM_MAYREAD |VM_RESERVED;
  	vma->vm_page_prot    = PAGE_READONLY; /* XXX may need to change */
  
  	/*
  	 * Now we have everything we need and we can initialize
  	 * and connect all the data structures
  	 */
  
  	ctx->ctx_smpl_hdr   = smpl_buf;
  	ctx->ctx_smpl_size  = size; /* aligned size */
  
  	/*
  	 * Let's do the difficult operations next.
  	 *
  	 * now we atomically find some area in the address space and
  	 * remap the buffer in it.
  	 */
  	down_write(&task->mm->mmap_sem);
  
  	/* find some free area in address space, must have mmap sem held */
  	vma->vm_start = pfm_get_unmapped_area(NULL, 0, size, 0, MAP_PRIVATE|MAP_ANONYMOUS, 0);
  	if (vma->vm_start == 0UL) {
  		DPRINT(("Cannot find unmapped area for size %ld
  ", size));
  		up_write(&task->mm->mmap_sem);
  		goto error;
  	}
  	vma->vm_end = vma->vm_start + size;
  	vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
  
  	DPRINT(("aligned size=%ld, hdr=%p mapped @0x%lx
  ", size, ctx->ctx_smpl_hdr, vma->vm_start));
  
  	/* can only be applied to current task, need to have the mm semaphore held when called */
  	if (pfm_remap_buffer(vma, (unsigned long)smpl_buf, vma->vm_start, size)) {
  		DPRINT(("Can't remap buffer
  "));
  		up_write(&task->mm->mmap_sem);
  		goto error;
  	}

  	get_file(filp);

  	/*
  	 * now insert the vma in the vm list for the process, must be
  	 * done with mmap lock held
  	 */
  	insert_vm_struct(mm, vma);
  
  	mm->total_vm  += size >> PAGE_SHIFT;

  	vm_stat_account(vma->vm_mm, vma->vm_flags, vma->vm_file,
  							vma_pages(vma));

  	up_write(&task->mm->mmap_sem);
  
  	/*
  	 * keep track of user level virtual address
  	 */
  	ctx->ctx_smpl_vaddr = (void *)vma->vm_start;
  	*(unsigned long *)user_vaddr = vma->vm_start;
  
  	return 0;
  
  error:
  	kmem_cache_free(vm_area_cachep, vma);
  error_kmem:
  	pfm_rvfree(smpl_buf, size);
  
  	return -ENOMEM;
  }
  
  /*
   * XXX: do something better here
   */
  static int
  pfm_bad_permissions(struct task_struct *task)
  {

  	const struct cred *tcred;

  	uid_t uid = current_uid();
  	gid_t gid = current_gid();

  	int ret;
  
  	rcu_read_lock();
  	tcred = __task_cred(task);

  	/* inspired by ptrace_attach() */
  	DPRINT(("cur: uid=%d gid=%d task: euid=%d suid=%d uid=%d egid=%d sgid=%d
  ",

  		uid,
  		gid,

  		tcred->euid,
  		tcred->suid,
  		tcred->uid,
  		tcred->egid,
  		tcred->sgid));
  
  	ret = ((uid != tcred->euid)
  	       || (uid != tcred->suid)
  	       || (uid != tcred->uid)
  	       || (gid != tcred->egid)
  	       || (gid != tcred->sgid)
  	       || (gid != tcred->gid)) && !capable(CAP_SYS_PTRACE);
  
  	rcu_read_unlock();
  	return ret;

  }
  
  static int
  pfarg_is_sane(struct task_struct *task, pfarg_context_t *pfx)
  {
  	int ctx_flags;
  
  	/* valid signal */
  
  	ctx_flags = pfx->ctx_flags;
  
  	if (ctx_flags & PFM_FL_SYSTEM_WIDE) {
  
  		/*
  		 * cannot block in this mode
  		 */
  		if (ctx_flags & PFM_FL_NOTIFY_BLOCK) {
  			DPRINT(("cannot use blocking mode when in system wide monitoring
  "));
  			return -EINVAL;
  		}
  	} else {
  	}
  	/* probably more to add here */
  
  	return 0;
  }
  
  static int

  pfm_setup_buffer_fmt(struct task_struct *task, struct file *filp, pfm_context_t *ctx, unsigned int ctx_flags,

  		     unsigned int cpu, pfarg_context_t *arg)
  {
  	pfm_buffer_fmt_t *fmt = NULL;
  	unsigned long size = 0UL;
  	void *uaddr = NULL;
  	void *fmt_arg = NULL;
  	int ret = 0;
  #define PFM_CTXARG_BUF_ARG(a)	(pfm_buffer_fmt_t *)(a+1)
  
  	/* invoke and lock buffer format, if found */
  	fmt = pfm_find_buffer_fmt(arg->ctx_smpl_buf_id);
  	if (fmt == NULL) {

  		DPRINT(("[%d] cannot find buffer format
  ", task_pid_nr(task)));

  		return -EINVAL;
  	}
  
  	/*
  	 * buffer argument MUST be contiguous to pfarg_context_t
  	 */
  	if (fmt->fmt_arg_size) fmt_arg = PFM_CTXARG_BUF_ARG(arg);
  
  	ret = pfm_buf_fmt_validate(fmt, task, ctx_flags, cpu, fmt_arg);

  	DPRINT(("[%d] after validate(0x%x,%d,%p)=%d
  ", task_pid_nr(task), ctx_flags, cpu, fmt_arg, ret));

  
  	if (ret) goto error;
  
  	/* link buffer format and context */
  	ctx->ctx_buf_fmt = fmt;

  	ctx->ctx_fl_is_sampling = 1; /* assume record() is defined */

  
  	/*
  	 * check if buffer format wants to use perfmon buffer allocation/mapping service
  	 */
  	ret = pfm_buf_fmt_getsize(fmt, task, ctx_flags, cpu, fmt_arg, &size);
  	if (ret) goto error;
  
  	if (size) {
  		/*
  		 * buffer is always remapped into the caller's address space
  		 */

  		ret = pfm_smpl_buffer_alloc(current, filp, ctx, size, &uaddr);

  		if (ret) goto error;
  
  		/* keep track of user address of buffer */
  		arg->ctx_smpl_vaddr = uaddr;
  	}
  	ret = pfm_buf_fmt_init(fmt, task, ctx->ctx_smpl_hdr, ctx_flags, cpu, fmt_arg);
  
  error:
  	return ret;
  }
  
  static void
  pfm_reset_pmu_state(pfm_context_t *ctx)
  {
  	int i;
  
  	/*
  	 * install reset values for PMC.
  	 */
  	for (i=1; PMC_IS_LAST(i) == 0; i++) {
  		if (PMC_IS_IMPL(i) == 0) continue;
  		ctx->ctx_pmcs[i] = PMC_DFL_VAL(i);
  		DPRINT(("pmc[%d]=0x%lx
  ", i, ctx->ctx_pmcs[i]));
  	}
  	/*
  	 * PMD registers are set to 0UL when the context in memset()
  	 */
  
  	/*
  	 * On context switched restore, we must restore ALL pmc and ALL pmd even
  	 * when they are not actively used by the task. In UP, the incoming process
  	 * may otherwise pick up left over PMC, PMD state from the previous process.
  	 * As opposed to PMD, stale PMC can cause harm to the incoming
  	 * process because they may change what is being measured.
  	 * Therefore, we must systematically reinstall the entire
  	 * PMC state. In SMP, the same thing is possible on the
  	 * same CPU but also on between 2 CPUs.
  	 *
  	 * The problem with PMD is information leaking especially
  	 * to user level when psr.sp=0
  	 *
  	 * There is unfortunately no easy way to avoid this problem
  	 * on either UP or SMP. This definitively slows down the
  	 * pfm_load_regs() function.
  	 */
  
  	 /*
  	  * bitmask of all PMCs accessible to this context
  	  *
  	  * PMC0 is treated differently.
  	  */
  	ctx->ctx_all_pmcs[0] = pmu_conf->impl_pmcs[0] & ~0x1;
  
  	/*

  	 * bitmask of all PMDs that are accessible to this context

  	 */
  	ctx->ctx_all_pmds[0] = pmu_conf->impl_pmds[0];
  
  	DPRINT(("<%d> all_pmcs=0x%lx all_pmds=0x%lx
  ", ctx->ctx_fd, ctx->ctx_all_pmcs[0],ctx->ctx_all_pmds[0]));
  
  	/*
  	 * useful in case of re-enable after disable
  	 */
  	ctx->ctx_used_ibrs[0] = 0UL;
  	ctx->ctx_used_dbrs[0] = 0UL;
  }
  
  static int
  pfm_ctx_getsize(void *arg, size_t *sz)
  {
  	pfarg_context_t *req = (pfarg_context_t *)arg;
  	pfm_buffer_fmt_t *fmt;
  
  	*sz = 0;
  
  	if (!pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) return 0;
  
  	fmt = pfm_find_buffer_fmt(req->ctx_smpl_buf_id);
  	if (fmt == NULL) {
  		DPRINT(("cannot find buffer format
  "));
  		return -EINVAL;
  	}
  	/* get just enough to copy in user parameters */
  	*sz = fmt->fmt_arg_size;
  	DPRINT(("arg_size=%lu
  ", *sz));
  
  	return 0;
  }
  
  
  
  /*
   * cannot attach if :
   * 	- kernel task
   * 	- task not owned by caller
   * 	- task incompatible with context mode
   */
  static int
  pfm_task_incompatible(pfm_context_t *ctx, struct task_struct *task)
  {
  	/*
  	 * no kernel task or task not owner by caller
  	 */
  	if (task->mm == NULL) {

  		DPRINT(("task [%d] has not memory context (kernel thread)
  ", task_pid_nr(task)));

  		return -EPERM;
  	}
  	if (pfm_bad_permissions(task)) {

  		DPRINT(("no permission to attach to  [%d]
  ", task_pid_nr(task)));

  		return -EPERM;
  	}
  	/*
  	 * cannot block in self-monitoring mode
  	 */
  	if (CTX_OVFL_NOBLOCK(ctx) == 0 && task == current) {

  		DPRINT(("cannot load a blocking context on self for [%d]
  ", task_pid_nr(task)));

  		return -EINVAL;
  	}
  
  	if (task->exit_state == EXIT_ZOMBIE) {

  		DPRINT(("cannot attach to  zombie task [%d]
  ", task_pid_nr(task)));

  		return -EBUSY;
  	}
  
  	/*
  	 * always ok for self
  	 */
  	if (task == current) return 0;

  	if (!task_is_stopped_or_traced(task)) {

  		DPRINT(("cannot attach to non-stopped task [%d] state=%ld
  ", task_pid_nr(task), task->state));

  		return -EBUSY;
  	}
  	/*
  	 * make sure the task is off any CPU
  	 */

  	wait_task_inactive(task, 0);

  
  	/* more to come... */
  
  	return 0;
  }
  
  static int
  pfm_get_task(pfm_context_t *ctx, pid_t pid, struct task_struct **task)
  {
  	struct task_struct *p = current;
  	int ret;
  
  	/* XXX: need to add more checks here */
  	if (pid < 2) return -EPERM;

  	if (pid != task_pid_vnr(current)) {

  
  		read_lock(&tasklist_lock);

  		p = find_task_by_vpid(pid);

  
  		/* make sure task cannot go away while we operate on it */
  		if (p) get_task_struct(p);
  
  		read_unlock(&tasklist_lock);
  
  		if (p == NULL) return -ESRCH;
  	}
  
  	ret = pfm_task_incompatible(ctx, p);
  	if (ret == 0) {
  		*task = p;
  	} else if (p != current) {
  		pfm_put_task(p);
  	}
  	return ret;
  }
  
  
  
  static int
  pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	pfarg_context_t *req = (pfarg_context_t *)arg;
  	struct file *filp;

  	struct path path;

  	int ctx_flags;

  	int fd;

  	int ret;
  
  	/* let's check the arguments first */
  	ret = pfarg_is_sane(current, req);

  	if (ret < 0)
  		return ret;

  
  	ctx_flags = req->ctx_flags;
  
  	ret = -ENOMEM;

  	fd = get_unused_fd();
  	if (fd < 0)
  		return fd;

  	ctx = pfm_context_alloc(ctx_flags);
  	if (!ctx)
  		goto error;

  	filp = pfm_alloc_file(ctx);
  	if (IS_ERR(filp)) {
  		ret = PTR_ERR(filp);
  		goto error_file;
  	}

  	req->ctx_fd = ctx->ctx_fd = fd;

  
  	/*
  	 * does the user want to sample?
  	 */
  	if (pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) {

  		ret = pfm_setup_buffer_fmt(current, filp, ctx, ctx_flags, 0, req);

  		if (ret)
  			goto buffer_error;

  	}

  	DPRINT(("ctx=%p flags=0x%x system=%d notify_block=%d excl_idle=%d no_msg=%d ctx_fd=%d
  ",

  		ctx,
  		ctx_flags,
  		ctx->ctx_fl_system,
  		ctx->ctx_fl_block,
  		ctx->ctx_fl_excl_idle,
  		ctx->ctx_fl_no_msg,
  		ctx->ctx_fd));
  
  	/*
  	 * initialize soft PMU state
  	 */
  	pfm_reset_pmu_state(ctx);

  	fd_install(fd, filp);

  	return 0;
  
  buffer_error:

  	path = filp->f_path;
  	put_filp(filp);
  	path_put(&path);

  
  	if (ctx->ctx_buf_fmt) {
  		pfm_buf_fmt_exit(ctx->ctx_buf_fmt, current, NULL, regs);
  	}
  error_file:
  	pfm_context_free(ctx);
  
  error:

  	put_unused_fd(fd);

  	return ret;
  }
  
  static inline unsigned long
  pfm_new_counter_value (pfm_counter_t *reg, int is_long_reset)
  {
  	unsigned long val = is_long_reset ? reg->long_reset : reg->short_reset;
  	unsigned long new_seed, old_seed = reg->seed, mask = reg->mask;
  	extern unsigned long carta_random32 (unsigned long seed);
  
  	if (reg->flags & PFM_REGFL_RANDOM) {
  		new_seed = carta_random32(old_seed);
  		val -= (old_seed & mask);	/* counter values are negative numbers! */
  		if ((mask >> 32) != 0)
  			/* construct a full 64-bit random value: */
  			new_seed |= carta_random32(old_seed >> 32) << 32;
  		reg->seed = new_seed;
  	}
  	reg->lval = val;
  	return val;
  }
  
  static void
  pfm_reset_regs_masked(pfm_context_t *ctx, unsigned long *ovfl_regs, int is_long_reset)
  {
  	unsigned long mask = ovfl_regs[0];
  	unsigned long reset_others = 0UL;
  	unsigned long val;
  	int i;
  
  	/*
  	 * now restore reset value on sampling overflowed counters
  	 */
  	mask >>= PMU_FIRST_COUNTER;
  	for(i = PMU_FIRST_COUNTER; mask; i++, mask >>= 1) {
  
  		if ((mask & 0x1UL) == 0UL) continue;
  
  		ctx->ctx_pmds[i].val = val = pfm_new_counter_value(ctx->ctx_pmds+ i, is_long_reset);
  		reset_others        |= ctx->ctx_pmds[i].reset_pmds[0];
  
  		DPRINT_ovfl((" %s reset ctx_pmds[%d]=%lx
  ", is_long_reset ? "long" : "short", i, val));
  	}
  
  	/*
  	 * Now take care of resetting the other registers
  	 */
  	for(i = 0; reset_others; i++, reset_others >>= 1) {
  
  		if ((reset_others & 0x1) == 0) continue;
  
  		ctx->ctx_pmds[i].val = val = pfm_new_counter_value(ctx->ctx_pmds + i, is_long_reset);
  
  		DPRINT_ovfl(("%s reset_others pmd[%d]=%lx
  ",
  			  is_long_reset ? "long" : "short", i, val));
  	}
  }
  
  static void
  pfm_reset_regs(pfm_context_t *ctx, unsigned long *ovfl_regs, int is_long_reset)
  {
  	unsigned long mask = ovfl_regs[0];
  	unsigned long reset_others = 0UL;
  	unsigned long val;
  	int i;
  
  	DPRINT_ovfl(("ovfl_regs=0x%lx is_long_reset=%d
  ", ovfl_regs[0], is_long_reset));
  
  	if (ctx->ctx_state == PFM_CTX_MASKED) {
  		pfm_reset_regs_masked(ctx, ovfl_regs, is_long_reset);
  		return;
  	}
  
  	/*
  	 * now restore reset value on sampling overflowed counters
  	 */
  	mask >>= PMU_FIRST_COUNTER;
  	for(i = PMU_FIRST_COUNTER; mask; i++, mask >>= 1) {
  
  		if ((mask & 0x1UL) == 0UL) continue;
  
  		val           = pfm_new_counter_value(ctx->ctx_pmds+ i, is_long_reset);
  		reset_others |= ctx->ctx_pmds[i].reset_pmds[0];
  
  		DPRINT_ovfl((" %s reset ctx_pmds[%d]=%lx
  ", is_long_reset ? "long" : "short", i, val));
  
  		pfm_write_soft_counter(ctx, i, val);
  	}
  
  	/*
  	 * Now take care of resetting the other registers
  	 */
  	for(i = 0; reset_others; i++, reset_others >>= 1) {
  
  		if ((reset_others & 0x1) == 0) continue;
  
  		val = pfm_new_counter_value(ctx->ctx_pmds + i, is_long_reset);
  
  		if (PMD_IS_COUNTING(i)) {
  			pfm_write_soft_counter(ctx, i, val);
  		} else {
  			ia64_set_pmd(i, val);
  		}
  		DPRINT_ovfl(("%s reset_others pmd[%d]=%lx
  ",
  			  is_long_reset ? "long" : "short", i, val));
  	}
  	ia64_srlz_d();
  }
  
  static int
  pfm_write_pmcs(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {

  	struct task_struct *task;
  	pfarg_reg_t *req = (pfarg_reg_t *)arg;
  	unsigned long value, pmc_pm;
  	unsigned long smpl_pmds, reset_pmds, impl_pmds;
  	unsigned int cnum, reg_flags, flags, pmc_type;
  	int i, can_access_pmu = 0, is_loaded, is_system, expert_mode;
  	int is_monitor, is_counting, state;
  	int ret = -EINVAL;
  	pfm_reg_check_t	wr_func;
  #define PFM_CHECK_PMC_PM(x, y, z) ((x)->ctx_fl_system ^ PMC_PM(y, z))
  
  	state     = ctx->ctx_state;
  	is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
  	is_system = ctx->ctx_fl_system;
  	task      = ctx->ctx_task;
  	impl_pmds = pmu_conf->impl_pmds[0];
  
  	if (state == PFM_CTX_ZOMBIE) return -EINVAL;
  
  	if (is_loaded) {

  		/*
  		 * In system wide and when the context is loaded, access can only happen
  		 * when the caller is running on the CPU being monitored by the session.
  		 * It does not have to be the owner (ctx_task) of the context per se.
  		 */
  		if (is_system && ctx->ctx_cpu != smp_processor_id()) {
  			DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  			return -EBUSY;
  		}
  		can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
  	}
  	expert_mode = pfm_sysctl.expert_mode; 
  
  	for (i = 0; i < count; i++, req++) {
  
  		cnum       = req->reg_num;
  		reg_flags  = req->reg_flags;
  		value      = req->reg_value;
  		smpl_pmds  = req->reg_smpl_pmds[0];
  		reset_pmds = req->reg_reset_pmds[0];
  		flags      = 0;
  
  
  		if (cnum >= PMU_MAX_PMCS) {
  			DPRINT(("pmc%u is invalid
  ", cnum));
  			goto error;
  		}
  
  		pmc_type   = pmu_conf->pmc_desc[cnum].type;
  		pmc_pm     = (value >> pmu_conf->pmc_desc[cnum].pm_pos) & 0x1;
  		is_counting = (pmc_type & PFM_REG_COUNTING) == PFM_REG_COUNTING ? 1 : 0;
  		is_monitor  = (pmc_type & PFM_REG_MONITOR) == PFM_REG_MONITOR ? 1 : 0;
  
  		/*
  		 * we reject all non implemented PMC as well
  		 * as attempts to modify PMC[0-3] which are used
  		 * as status registers by the PMU
  		 */
  		if ((pmc_type & PFM_REG_IMPL) == 0 || (pmc_type & PFM_REG_CONTROL) == PFM_REG_CONTROL) {
  			DPRINT(("pmc%u is unimplemented or no-access pmc_type=%x
  ", cnum, pmc_type));
  			goto error;
  		}
  		wr_func = pmu_conf->pmc_desc[cnum].write_check;
  		/*
  		 * If the PMC is a monitor, then if the value is not the default:
  		 * 	- system-wide session: PMCx.pm=1 (privileged monitor)
  		 * 	- per-task           : PMCx.pm=0 (user monitor)
  		 */
  		if (is_monitor && value != PMC_DFL_VAL(cnum) && is_system ^ pmc_pm) {
  			DPRINT(("pmc%u pmc_pm=%lu is_system=%d
  ",
  				cnum,
  				pmc_pm,
  				is_system));
  			goto error;
  		}
  
  		if (is_counting) {
  			/*
  		 	 * enforce generation of overflow interrupt. Necessary on all
  		 	 * CPUs.
  		 	 */
  			value |= 1 << PMU_PMC_OI;
  
  			if (reg_flags & PFM_REGFL_OVFL_NOTIFY) {
  				flags |= PFM_REGFL_OVFL_NOTIFY;
  			}
  
  			if (reg_flags & PFM_REGFL_RANDOM) flags |= PFM_REGFL_RANDOM;
  
  			/* verify validity of smpl_pmds */
  			if ((smpl_pmds & impl_pmds) != smpl_pmds) {
  				DPRINT(("invalid smpl_pmds 0x%lx for pmc%u
  ", smpl_pmds, cnum));
  				goto error;
  			}
  
  			/* verify validity of reset_pmds */
  			if ((reset_pmds & impl_pmds) != reset_pmds) {
  				DPRINT(("invalid reset_pmds 0x%lx for pmc%u
  ", reset_pmds, cnum));
  				goto error;
  			}
  		} else {
  			if (reg_flags & (PFM_REGFL_OVFL_NOTIFY|PFM_REGFL_RANDOM)) {
  				DPRINT(("cannot set ovfl_notify or random on pmc%u
  ", cnum));
  				goto error;
  			}
  			/* eventid on non-counting monitors are ignored */
  		}
  
  		/*
  		 * execute write checker, if any
  		 */
  		if (likely(expert_mode == 0 && wr_func)) {
  			ret = (*wr_func)(task, ctx, cnum, &value, regs);
  			if (ret) goto error;
  			ret = -EINVAL;
  		}
  
  		/*
  		 * no error on this register
  		 */
  		PFM_REG_RETFLAG_SET(req->reg_flags, 0);
  
  		/*
  		 * Now we commit the changes to the software state
  		 */
  
  		/*
  		 * update overflow information
  		 */
  		if (is_counting) {
  			/*
  		 	 * full flag update each time a register is programmed
  		 	 */
  			ctx->ctx_pmds[cnum].flags = flags;
  
  			ctx->ctx_pmds[cnum].reset_pmds[0] = reset_pmds;
  			ctx->ctx_pmds[cnum].smpl_pmds[0]  = smpl_pmds;
  			ctx->ctx_pmds[cnum].eventid       = req->reg_smpl_eventid;
  
  			/*
  			 * Mark all PMDS to be accessed as used.
  			 *
  			 * We do not keep track of PMC because we have to
  			 * systematically restore ALL of them.
  			 *
  			 * We do not update the used_monitors mask, because
  			 * if we have not programmed them, then will be in
  			 * a quiescent state, therefore we will not need to
  			 * mask/restore then when context is MASKED.
  			 */
  			CTX_USED_PMD(ctx, reset_pmds);
  			CTX_USED_PMD(ctx, smpl_pmds);
  			/*
  		 	 * make sure we do not try to reset on
  		 	 * restart because we have established new values
  		 	 */
  			if (state == PFM_CTX_MASKED) ctx->ctx_ovfl_regs[0] &= ~1UL << cnum;
  		}
  		/*
  		 * Needed in case the user does not initialize the equivalent
  		 * PMD. Clearing is done indirectly via pfm_reset_pmu_state() so there is no
  		 * possible leak here.
  		 */
  		CTX_USED_PMD(ctx, pmu_conf->pmc_desc[cnum].dep_pmd[0]);
  
  		/*
  		 * keep track of the monitor PMC that we are using.
  		 * we save the value of the pmc in ctx_pmcs[] and if
  		 * the monitoring is not stopped for the context we also
  		 * place it in the saved state area so that it will be
  		 * picked up later by the context switch code.
  		 *
  		 * The value in ctx_pmcs[] can only be changed in pfm_write_pmcs().
  		 *

  		 * The value in th_pmcs[] may be modified on overflow, i.e.,  when

  		 * monitoring needs to be stopped.
  		 */
  		if (is_monitor) CTX_USED_MONITOR(ctx, 1UL << cnum);
  
  		/*
  		 * update context state
  		 */
  		ctx->ctx_pmcs[cnum] = value;
  
  		if (is_loaded) {
  			/*
  			 * write thread state
  			 */

  			if (is_system == 0) ctx->th_pmcs[cnum] = value;

  
  			/*
  			 * write hardware register if we can
  			 */
  			if (can_access_pmu) {
  				ia64_set_pmc(cnum, value);
  			}
  #ifdef CONFIG_SMP
  			else {
  				/*
  				 * per-task SMP only here
  				 *
  			 	 * we are guaranteed that the task is not running on the other CPU,
  			 	 * we indicate that this PMD will need to be reloaded if the task
  			 	 * is rescheduled on the CPU it ran last on.
  			 	 */
  				ctx->ctx_reload_pmcs[0] |= 1UL << cnum;
  			}
  #endif
  		}
  
  		DPRINT(("pmc[%u]=0x%lx ld=%d apmu=%d flags=0x%x all_pmcs=0x%lx used_pmds=0x%lx eventid=%ld smpl_pmds=0x%lx reset_pmds=0x%lx reloads_pmcs=0x%lx used_monitors=0x%lx ovfl_regs=0x%lx
  ",
  			  cnum,
  			  value,
  			  is_loaded,
  			  can_access_pmu,
  			  flags,
  			  ctx->ctx_all_pmcs[0],
  			  ctx->ctx_used_pmds[0],
  			  ctx->ctx_pmds[cnum].eventid,
  			  smpl_pmds,
  			  reset_pmds,
  			  ctx->ctx_reload_pmcs[0],
  			  ctx->ctx_used_monitors[0],
  			  ctx->ctx_ovfl_regs[0]));
  	}
  
  	/*
  	 * make sure the changes are visible
  	 */
  	if (can_access_pmu) ia64_srlz_d();
  
  	return 0;
  error:
  	PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
  	return ret;
  }
  
  static int
  pfm_write_pmds(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {

  	struct task_struct *task;
  	pfarg_reg_t *req = (pfarg_reg_t *)arg;
  	unsigned long value, hw_value, ovfl_mask;
  	unsigned int cnum;
  	int i, can_access_pmu = 0, state;
  	int is_counting, is_loaded, is_system, expert_mode;
  	int ret = -EINVAL;
  	pfm_reg_check_t wr_func;
  
  
  	state     = ctx->ctx_state;
  	is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
  	is_system = ctx->ctx_fl_system;
  	ovfl_mask = pmu_conf->ovfl_val;
  	task      = ctx->ctx_task;
  
  	if (unlikely(state == PFM_CTX_ZOMBIE)) return -EINVAL;
  
  	/*
  	 * on both UP and SMP, we can only write to the PMC when the task is
  	 * the owner of the local PMU.
  	 */
  	if (likely(is_loaded)) {

  		/*
  		 * In system wide and when the context is loaded, access can only happen
  		 * when the caller is running on the CPU being monitored by the session.
  		 * It does not have to be the owner (ctx_task) of the context per se.
  		 */
  		if (unlikely(is_system && ctx->ctx_cpu != smp_processor_id())) {
  			DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  			return -EBUSY;
  		}
  		can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
  	}
  	expert_mode = pfm_sysctl.expert_mode; 
  
  	for (i = 0; i < count; i++, req++) {
  
  		cnum  = req->reg_num;
  		value = req->reg_value;
  
  		if (!PMD_IS_IMPL(cnum)) {
  			DPRINT(("pmd[%u] is unimplemented or invalid
  ", cnum));
  			goto abort_mission;
  		}
  		is_counting = PMD_IS_COUNTING(cnum);
  		wr_func     = pmu_conf->pmd_desc[cnum].write_check;
  
  		/*
  		 * execute write checker, if any
  		 */
  		if (unlikely(expert_mode == 0 && wr_func)) {
  			unsigned long v = value;
  
  			ret = (*wr_func)(task, ctx, cnum, &v, regs);
  			if (ret) goto abort_mission;
  
  			value = v;
  			ret   = -EINVAL;
  		}
  
  		/*
  		 * no error on this register
  		 */
  		PFM_REG_RETFLAG_SET(req->reg_flags, 0);
  
  		/*
  		 * now commit changes to software state
  		 */
  		hw_value = value;
  
  		/*
  		 * update virtualized (64bits) counter
  		 */
  		if (is_counting) {
  			/*
  			 * write context state
  			 */
  			ctx->ctx_pmds[cnum].lval = value;
  
  			/*
  			 * when context is load we use the split value
  			 */
  			if (is_loaded) {
  				hw_value = value &  ovfl_mask;
  				value    = value & ~ovfl_mask;
  			}
  		}
  		/*
  		 * update reset values (not just for counters)
  		 */
  		ctx->ctx_pmds[cnum].long_reset  = req->reg_long_reset;
  		ctx->ctx_pmds[cnum].short_reset = req->reg_short_reset;
  
  		/*
  		 * update randomization parameters (not just for counters)
  		 */
  		ctx->ctx_pmds[cnum].seed = req->reg_random_seed;
  		ctx->ctx_pmds[cnum].mask = req->reg_random_mask;
  
  		/*
  		 * update context value
  		 */
  		ctx->ctx_pmds[cnum].val  = value;
  
  		/*
  		 * Keep track of what we use
  		 *
  		 * We do not keep track of PMC because we have to
  		 * systematically restore ALL of them.
  		 */
  		CTX_USED_PMD(ctx, PMD_PMD_DEP(cnum));
  
  		/*
  		 * mark this PMD register used as well
  		 */
  		CTX_USED_PMD(ctx, RDEP(cnum));
  
  		/*
  		 * make sure we do not try to reset on
  		 * restart because we have established new values
  		 */
  		if (is_counting && state == PFM_CTX_MASKED) {
  			ctx->ctx_ovfl_regs[0] &= ~1UL << cnum;
  		}
  
  		if (is_loaded) {
  			/*
  		 	 * write thread state
  		 	 */

  			if (is_system == 0) ctx->th_pmds[cnum] = hw_value;

  
  			/*
  			 * write hardware register if we can
  			 */
  			if (can_access_pmu) {
  				ia64_set_pmd(cnum, hw_value);
  			} else {
  #ifdef CONFIG_SMP
  				/*
  			 	 * we are guaranteed that the task is not running on the other CPU,
  			 	 * we indicate that this PMD will need to be reloaded if the task
  			 	 * is rescheduled on the CPU it ran last on.
  			 	 */
  				ctx->ctx_reload_pmds[0] |= 1UL << cnum;
  #endif
  			}
  		}
  
  		DPRINT(("pmd[%u]=0x%lx ld=%d apmu=%d, hw_value=0x%lx ctx_pmd=0x%lx  short_reset=0x%lx "
  			  "long_reset=0x%lx notify=%c seed=0x%lx mask=0x%lx used_pmds=0x%lx reset_pmds=0x%lx reload_pmds=0x%lx all_pmds=0x%lx ovfl_regs=0x%lx
  ",
  			cnum,
  			value,
  			is_loaded,
  			can_access_pmu,
  			hw_value,
  			ctx->ctx_pmds[cnum].val,
  			ctx->ctx_pmds[cnum].short_reset,
  			ctx->ctx_pmds[cnum].long_reset,
  			PMC_OVFL_NOTIFY(ctx, cnum) ? 'Y':'N',
  			ctx->ctx_pmds[cnum].seed,
  			ctx->ctx_pmds[cnum].mask,
  			ctx->ctx_used_pmds[0],
  			ctx->ctx_pmds[cnum].reset_pmds[0],
  			ctx->ctx_reload_pmds[0],
  			ctx->ctx_all_pmds[0],
  			ctx->ctx_ovfl_regs[0]));
  	}
  
  	/*
  	 * make changes visible
  	 */
  	if (can_access_pmu) ia64_srlz_d();
  
  	return 0;
  
  abort_mission:
  	/*
  	 * for now, we have only one possibility for error
  	 */
  	PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
  	return ret;
  }
  
  /*
   * By the way of PROTECT_CONTEXT(), interrupts are masked while we are in this function.
   * Therefore we know, we do not have to worry about the PMU overflow interrupt. If an
   * interrupt is delivered during the call, it will be kept pending until we leave, making
   * it appears as if it had been generated at the UNPROTECT_CONTEXT(). At least we are
   * guaranteed to return consistent data to the user, it may simply be old. It is not
   * trivial to treat the overflow while inside the call because you may end up in
   * some module sampling buffer code causing deadlocks.
   */
  static int
  pfm_read_pmds(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {

  	struct task_struct *task;
  	unsigned long val = 0UL, lval, ovfl_mask, sval;
  	pfarg_reg_t *req = (pfarg_reg_t *)arg;
  	unsigned int cnum, reg_flags = 0;
  	int i, can_access_pmu = 0, state;
  	int is_loaded, is_system, is_counting, expert_mode;
  	int ret = -EINVAL;
  	pfm_reg_check_t rd_func;
  
  	/*
  	 * access is possible when loaded only for
  	 * self-monitoring tasks or in UP mode
  	 */
  
  	state     = ctx->ctx_state;
  	is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
  	is_system = ctx->ctx_fl_system;
  	ovfl_mask = pmu_conf->ovfl_val;
  	task      = ctx->ctx_task;
  
  	if (state == PFM_CTX_ZOMBIE) return -EINVAL;
  
  	if (likely(is_loaded)) {

  		/*
  		 * In system wide and when the context is loaded, access can only happen
  		 * when the caller is running on the CPU being monitored by the session.
  		 * It does not have to be the owner (ctx_task) of the context per se.
  		 */
  		if (unlikely(is_system && ctx->ctx_cpu != smp_processor_id())) {
  			DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  			return -EBUSY;
  		}
  		/*
  		 * this can be true when not self-monitoring only in UP
  		 */
  		can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
  
  		if (can_access_pmu) ia64_srlz_d();
  	}
  	expert_mode = pfm_sysctl.expert_mode; 
  
  	DPRINT(("ld=%d apmu=%d ctx_state=%d
  ",
  		is_loaded,
  		can_access_pmu,
  		state));
  
  	/*
  	 * on both UP and SMP, we can only read the PMD from the hardware register when
  	 * the task is the owner of the local PMU.
  	 */
  
  	for (i = 0; i < count; i++, req++) {
  
  		cnum        = req->reg_num;
  		reg_flags   = req->reg_flags;
  
  		if (unlikely(!PMD_IS_IMPL(cnum))) goto error;
  		/*
  		 * we can only read the register that we use. That includes

  		 * the one we explicitly initialize AND the one we want included

  		 * in the sampling buffer (smpl_regs).
  		 *
  		 * Having this restriction allows optimization in the ctxsw routine
  		 * without compromising security (leaks)
  		 */
  		if (unlikely(!CTX_IS_USED_PMD(ctx, cnum))) goto error;
  
  		sval        = ctx->ctx_pmds[cnum].val;
  		lval        = ctx->ctx_pmds[cnum].lval;
  		is_counting = PMD_IS_COUNTING(cnum);
  
  		/*
  		 * If the task is not the current one, then we check if the
  		 * PMU state is still in the local live register due to lazy ctxsw.
  		 * If true, then we read directly from the registers.
  		 */
  		if (can_access_pmu){
  			val = ia64_get_pmd(cnum);
  		} else {
  			/*
  			 * context has been saved
  			 * if context is zombie, then task does not exist anymore.
  			 * In this case, we use the full value saved in the context (pfm_flush_regs()).
  			 */

  			val = is_loaded ? ctx->th_pmds[cnum] : 0UL;

  		}
  		rd_func = pmu_conf->pmd_desc[cnum].read_check;
  
  		if (is_counting) {
  			/*
  			 * XXX: need to check for overflow when loaded
  			 */
  			val &= ovfl_mask;
  			val += sval;
  		}
  
  		/*
  		 * execute read checker, if any
  		 */
  		if (unlikely(expert_mode == 0 && rd_func)) {
  			unsigned long v = val;
  			ret = (*rd_func)(ctx->ctx_task, ctx, cnum, &v, regs);
  			if (ret) goto error;
  			val = v;
  			ret = -EINVAL;
  		}
  
  		PFM_REG_RETFLAG_SET(reg_flags, 0);
  
  		DPRINT(("pmd[%u]=0x%lx
  ", cnum, val));
  
  		/*
  		 * update register return value, abort all if problem during copy.
  		 * we only modify the reg_flags field. no check mode is fine because
  		 * access has been verified upfront in sys_perfmonctl().
  		 */
  		req->reg_value            = val;
  		req->reg_flags            = reg_flags;
  		req->reg_last_reset_val   = lval;
  	}
  
  	return 0;
  
  error:
  	PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
  	return ret;
  }
  
  int
  pfm_mod_write_pmcs(struct task_struct *task, void *req, unsigned int nreq, struct pt_regs *regs)
  {
  	pfm_context_t *ctx;
  
  	if (req == NULL) return -EINVAL;
  
   	ctx = GET_PMU_CTX();
  
  	if (ctx == NULL) return -EINVAL;
  
  	/*
  	 * for now limit to current task, which is enough when calling
  	 * from overflow handler
  	 */
  	if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
  
  	return pfm_write_pmcs(ctx, req, nreq, regs);
  }
  EXPORT_SYMBOL(pfm_mod_write_pmcs);
  
  int
  pfm_mod_read_pmds(struct task_struct *task, void *req, unsigned int nreq, struct pt_regs *regs)
  {
  	pfm_context_t *ctx;
  
  	if (req == NULL) return -EINVAL;
  
   	ctx = GET_PMU_CTX();
  
  	if (ctx == NULL) return -EINVAL;
  
  	/*
  	 * for now limit to current task, which is enough when calling
  	 * from overflow handler
  	 */
  	if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
  
  	return pfm_read_pmds(ctx, req, nreq, regs);
  }
  EXPORT_SYMBOL(pfm_mod_read_pmds);
  
  /*
   * Only call this function when a process it trying to
   * write the debug registers (reading is always allowed)
   */
  int
  pfm_use_debug_registers(struct task_struct *task)
  {
  	pfm_context_t *ctx = task->thread.pfm_context;
  	unsigned long flags;
  	int ret = 0;
  
  	if (pmu_conf->use_rr_dbregs == 0) return 0;

  	DPRINT(("called for [%d]
  ", task_pid_nr(task)));

  
  	/*
  	 * do it only once
  	 */
  	if (task->thread.flags & IA64_THREAD_DBG_VALID) return 0;
  
  	/*
  	 * Even on SMP, we do not need to use an atomic here because
  	 * the only way in is via ptrace() and this is possible only when the
  	 * process is stopped. Even in the case where the ctxsw out is not totally
  	 * completed by the time we come here, there is no way the 'stopped' process
  	 * could be in the middle of fiddling with the pfm_write_ibr_dbr() routine.
  	 * So this is always safe.
  	 */
  	if (ctx && ctx->ctx_fl_using_dbreg == 1) return -1;
  
  	LOCK_PFS(flags);
  
  	/*
  	 * We cannot allow setting breakpoints when system wide monitoring
  	 * sessions are using the debug registers.
  	 */
  	if (pfm_sessions.pfs_sys_use_dbregs> 0)
  		ret = -1;
  	else
  		pfm_sessions.pfs_ptrace_use_dbregs++;
  
  	DPRINT(("ptrace_use_dbregs=%u  sys_use_dbregs=%u by [%d] ret = %d
  ",
  		  pfm_sessions.pfs_ptrace_use_dbregs,
  		  pfm_sessions.pfs_sys_use_dbregs,

  		  task_pid_nr(task), ret));

  
  	UNLOCK_PFS(flags);
  
  	return ret;
  }
  
  /*
   * This function is called for every task that exits with the
   * IA64_THREAD_DBG_VALID set. This indicates a task which was
   * able to use the debug registers for debugging purposes via
   * ptrace(). Therefore we know it was not using them for

   * performance monitoring, so we only decrement the number

   * of "ptraced" debug register users to keep the count up to date
   */
  int
  pfm_release_debug_registers(struct task_struct *task)
  {
  	unsigned long flags;
  	int ret;
  
  	if (pmu_conf->use_rr_dbregs == 0) return 0;
  
  	LOCK_PFS(flags);
  	if (pfm_sessions.pfs_ptrace_use_dbregs == 0) {

  		printk(KERN_ERR "perfmon: invalid release for [%d] ptrace_use_dbregs=0
  ", task_pid_nr(task));

  		ret = -1;
  	}  else {
  		pfm_sessions.pfs_ptrace_use_dbregs--;
  		ret = 0;
  	}
  	UNLOCK_PFS(flags);
  
  	return ret;
  }
  
  static int
  pfm_restart(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	struct task_struct *task;
  	pfm_buffer_fmt_t *fmt;
  	pfm_ovfl_ctrl_t rst_ctrl;
  	int state, is_system;
  	int ret = 0;
  
  	state     = ctx->ctx_state;
  	fmt       = ctx->ctx_buf_fmt;
  	is_system = ctx->ctx_fl_system;
  	task      = PFM_CTX_TASK(ctx);
  
  	switch(state) {
  		case PFM_CTX_MASKED:
  			break;
  		case PFM_CTX_LOADED: 
  			if (CTX_HAS_SMPL(ctx) && fmt->fmt_restart_active) break;
  			/* fall through */
  		case PFM_CTX_UNLOADED:
  		case PFM_CTX_ZOMBIE:
  			DPRINT(("invalid state=%d
  ", state));
  			return -EBUSY;
  		default:
  			DPRINT(("state=%d, cannot operate (no active_restart handler)
  ", state));
  			return -EINVAL;
  	}
  
  	/*
   	 * In system wide and when the context is loaded, access can only happen
   	 * when the caller is running on the CPU being monitored by the session.
   	 * It does not have to be the owner (ctx_task) of the context per se.
   	 */
  	if (is_system && ctx->ctx_cpu != smp_processor_id()) {
  		DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  		return -EBUSY;
  	}
  
  	/* sanity check */
  	if (unlikely(task == NULL)) {

  		printk(KERN_ERR "perfmon: [%d] pfm_restart no task
  ", task_pid_nr(current));

  		return -EINVAL;
  	}
  
  	if (task == current || is_system) {
  
  		fmt = ctx->ctx_buf_fmt;
  
  		DPRINT(("restarting self %d ovfl=0x%lx
  ",

  			task_pid_nr(task),

  			ctx->ctx_ovfl_regs[0]));
  
  		if (CTX_HAS_SMPL(ctx)) {
  
  			prefetch(ctx->ctx_smpl_hdr);
  
  			rst_ctrl.bits.mask_monitoring = 0;
  			rst_ctrl.bits.reset_ovfl_pmds = 0;
  
  			if (state == PFM_CTX_LOADED)
  				ret = pfm_buf_fmt_restart_active(fmt, task, &rst_ctrl, ctx->ctx_smpl_hdr, regs);
  			else
  				ret = pfm_buf_fmt_restart(fmt, task, &rst_ctrl, ctx->ctx_smpl_hdr, regs);
  		} else {
  			rst_ctrl.bits.mask_monitoring = 0;
  			rst_ctrl.bits.reset_ovfl_pmds = 1;
  		}
  
  		if (ret == 0) {
  			if (rst_ctrl.bits.reset_ovfl_pmds)
  				pfm_reset_regs(ctx, ctx->ctx_ovfl_regs, PFM_PMD_LONG_RESET);
  
  			if (rst_ctrl.bits.mask_monitoring == 0) {

  				DPRINT(("resuming monitoring for [%d]
  ", task_pid_nr(task)));

  
  				if (state == PFM_CTX_MASKED) pfm_restore_monitoring(task);
  			} else {

  				DPRINT(("keeping monitoring stopped for [%d]
  ", task_pid_nr(task)));

  
  				// cannot use pfm_stop_monitoring(task, regs);
  			}
  		}
  		/*
  		 * clear overflowed PMD mask to remove any stale information
  		 */
  		ctx->ctx_ovfl_regs[0] = 0UL;
  
  		/*
  		 * back to LOADED state
  		 */
  		ctx->ctx_state = PFM_CTX_LOADED;
  
  		/*
  		 * XXX: not really useful for self monitoring
  		 */
  		ctx->ctx_fl_can_restart = 0;
  
  		return 0;
  	}
  
  	/* 
  	 * restart another task
  	 */
  
  	/*
  	 * When PFM_CTX_MASKED, we cannot issue a restart before the previous 
  	 * one is seen by the task.
  	 */
  	if (state == PFM_CTX_MASKED) {
  		if (ctx->ctx_fl_can_restart == 0) return -EINVAL;
  		/*
  		 * will prevent subsequent restart before this one is
  		 * seen by other task
  		 */
  		ctx->ctx_fl_can_restart = 0;
  	}
  
  	/*
  	 * if blocking, then post the semaphore is PFM_CTX_MASKED, i.e.
  	 * the task is blocked or on its way to block. That's the normal
  	 * restart path. If the monitoring is not masked, then the task
  	 * can be actively monitoring and we cannot directly intervene.
  	 * Therefore we use the trap mechanism to catch the task and
  	 * force it to reset the buffer/reset PMDs.
  	 *
  	 * if non-blocking, then we ensure that the task will go into
  	 * pfm_handle_work() before returning to user mode.
  	 *

  	 * We cannot explicitly reset another task, it MUST always

  	 * be done by the task itself. This works for system wide because
  	 * the tool that is controlling the session is logically doing 
  	 * "self-monitoring".
  	 */
  	if (CTX_OVFL_NOBLOCK(ctx) == 0 && state == PFM_CTX_MASKED) {

  		DPRINT(("unblocking [%d]
  ", task_pid_nr(task)));

  		complete(&ctx->ctx_restart_done);

  	} else {

  		DPRINT(("[%d] armed exit trap
  ", task_pid_nr(task)));

  
  		ctx->ctx_fl_trap_reason = PFM_TRAP_REASON_RESET;
  
  		PFM_SET_WORK_PENDING(task, 1);

  		set_notify_resume(task);

  
  		/*
  		 * XXX: send reschedule if task runs on another CPU
  		 */
  	}
  	return 0;
  }
  
  static int
  pfm_debug(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	unsigned int m = *(unsigned int *)arg;
  
  	pfm_sysctl.debug = m == 0 ? 0 : 1;

  	printk(KERN_INFO "perfmon debugging %s (timing reset)
  ", pfm_sysctl.debug ? "on" : "off");
  
  	if (m == 0) {
  		memset(pfm_stats, 0, sizeof(pfm_stats));
  		for(m=0; m < NR_CPUS; m++) pfm_stats[m].pfm_ovfl_intr_cycles_min = ~0UL;
  	}
  	return 0;
  }
  
  /*
   * arg can be NULL and count can be zero for this function
   */
  static int
  pfm_write_ibr_dbr(int mode, pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	struct thread_struct *thread = NULL;
  	struct task_struct *task;
  	pfarg_dbreg_t *req = (pfarg_dbreg_t *)arg;
  	unsigned long flags;
  	dbreg_t dbreg;
  	unsigned int rnum;
  	int first_time;
  	int ret = 0, state;
  	int i, can_access_pmu = 0;
  	int is_system, is_loaded;
  
  	if (pmu_conf->use_rr_dbregs == 0) return -EINVAL;
  
  	state     = ctx->ctx_state;
  	is_loaded = state == PFM_CTX_LOADED ? 1 : 0;
  	is_system = ctx->ctx_fl_system;
  	task      = ctx->ctx_task;
  
  	if (state == PFM_CTX_ZOMBIE) return -EINVAL;
  
  	/*
  	 * on both UP and SMP, we can only write to the PMC when the task is
  	 * the owner of the local PMU.
  	 */
  	if (is_loaded) {
  		thread = &task->thread;
  		/*
  		 * In system wide and when the context is loaded, access can only happen
  		 * when the caller is running on the CPU being monitored by the session.
  		 * It does not have to be the owner (ctx_task) of the context per se.
  		 */
  		if (unlikely(is_system && ctx->ctx_cpu != smp_processor_id())) {
  			DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  			return -EBUSY;
  		}
  		can_access_pmu = GET_PMU_OWNER() == task || is_system ? 1 : 0;
  	}
  
  	/*
  	 * we do not need to check for ipsr.db because we do clear ibr.x, dbr.r, and dbr.w
  	 * ensuring that no real breakpoint can be installed via this call.
  	 *
  	 * IMPORTANT: regs can be NULL in this function
  	 */
  
  	first_time = ctx->ctx_fl_using_dbreg == 0;
  
  	/*
  	 * don't bother if we are loaded and task is being debugged
  	 */
  	if (is_loaded && (thread->flags & IA64_THREAD_DBG_VALID) != 0) {

  		DPRINT(("debug registers already in use for [%d]
  ", task_pid_nr(task)));

  		return -EBUSY;
  	}
  
  	/*
  	 * check for debug registers in system wide mode
  	 *
  	 * If though a check is done in pfm_context_load(),
  	 * we must repeat it here, in case the registers are
  	 * written after the context is loaded
  	 */
  	if (is_loaded) {
  		LOCK_PFS(flags);
  
  		if (first_time && is_system) {
  			if (pfm_sessions.pfs_ptrace_use_dbregs)
  				ret = -EBUSY;
  			else
  				pfm_sessions.pfs_sys_use_dbregs++;
  		}
  		UNLOCK_PFS(flags);
  	}
  
  	if (ret != 0) return ret;
  
  	/*
  	 * mark ourself as user of the debug registers for
  	 * perfmon purposes.
  	 */
  	ctx->ctx_fl_using_dbreg = 1;
  
  	/*
   	 * clear hardware registers to make sure we don't
   	 * pick up stale state.
  	 *
  	 * for a system wide session, we do not use
  	 * thread.dbr, thread.ibr because this process
  	 * never leaves the current CPU and the state
  	 * is shared by all processes running on it
   	 */
  	if (first_time && can_access_pmu) {

  		DPRINT(("[%d] clearing ibrs, dbrs
  ", task_pid_nr(task)));

  		for (i=0; i < pmu_conf->num_ibrs; i++) {
  			ia64_set_ibr(i, 0UL);
  			ia64_dv_serialize_instruction();
  		}
  		ia64_srlz_i();
  		for (i=0; i < pmu_conf->num_dbrs; i++) {
  			ia64_set_dbr(i, 0UL);
  			ia64_dv_serialize_data();
  		}
  		ia64_srlz_d();
  	}
  
  	/*
  	 * Now install the values into the registers
  	 */
  	for (i = 0; i < count; i++, req++) {
  
  		rnum      = req->dbreg_num;
  		dbreg.val = req->dbreg_value;
  
  		ret = -EINVAL;
  
  		if ((mode == PFM_CODE_RR && rnum >= PFM_NUM_IBRS) || ((mode == PFM_DATA_RR) && rnum >= PFM_NUM_DBRS)) {
  			DPRINT(("invalid register %u val=0x%lx mode=%d i=%d count=%d
  ",
  				  rnum, dbreg.val, mode, i, count));
  
  			goto abort_mission;
  		}
  
  		/*
  		 * make sure we do not install enabled breakpoint
  		 */
  		if (rnum & 0x1) {
  			if (mode == PFM_CODE_RR)
  				dbreg.ibr.ibr_x = 0;
  			else
  				dbreg.dbr.dbr_r = dbreg.dbr.dbr_w = 0;
  		}
  
  		PFM_REG_RETFLAG_SET(req->dbreg_flags, 0);
  
  		/*
  		 * Debug registers, just like PMC, can only be modified
  		 * by a kernel call. Moreover, perfmon() access to those
  		 * registers are centralized in this routine. The hardware
  		 * does not modify the value of these registers, therefore,
  		 * if we save them as they are written, we can avoid having
  		 * to save them on context switch out. This is made possible
  		 * by the fact that when perfmon uses debug registers, ptrace()
  		 * won't be able to modify them concurrently.
  		 */
  		if (mode == PFM_CODE_RR) {
  			CTX_USED_IBR(ctx, rnum);
  
  			if (can_access_pmu) {
  				ia64_set_ibr(rnum, dbreg.val);
  				ia64_dv_serialize_instruction();
  			}
  
  			ctx->ctx_ibrs[rnum] = dbreg.val;
  
  			DPRINT(("write ibr%u=0x%lx used_ibrs=0x%x ld=%d apmu=%d
  ",
  				rnum, dbreg.val, ctx->ctx_used_ibrs[0], is_loaded, can_access_pmu));
  		} else {
  			CTX_USED_DBR(ctx, rnum);
  
  			if (can_access_pmu) {
  				ia64_set_dbr(rnum, dbreg.val);
  				ia64_dv_serialize_data();
  			}
  			ctx->ctx_dbrs[rnum] = dbreg.val;
  
  			DPRINT(("write dbr%u=0x%lx used_dbrs=0x%x ld=%d apmu=%d
  ",
  				rnum, dbreg.val, ctx->ctx_used_dbrs[0], is_loaded, can_access_pmu));
  		}
  	}
  
  	return 0;
  
  abort_mission:
  	/*
  	 * in case it was our first attempt, we undo the global modifications
  	 */
  	if (first_time) {
  		LOCK_PFS(flags);
  		if (ctx->ctx_fl_system) {
  			pfm_sessions.pfs_sys_use_dbregs--;
  		}
  		UNLOCK_PFS(flags);
  		ctx->ctx_fl_using_dbreg = 0;
  	}
  	/*
  	 * install error return flag
  	 */
  	PFM_REG_RETFLAG_SET(req->dbreg_flags, PFM_REG_RETFL_EINVAL);
  
  	return ret;
  }
  
  static int
  pfm_write_ibrs(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	return pfm_write_ibr_dbr(PFM_CODE_RR, ctx, arg, count, regs);
  }
  
  static int
  pfm_write_dbrs(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	return pfm_write_ibr_dbr(PFM_DATA_RR, ctx, arg, count, regs);
  }
  
  int
  pfm_mod_write_ibrs(struct task_struct *task, void *req, unsigned int nreq, struct pt_regs *regs)
  {
  	pfm_context_t *ctx;
  
  	if (req == NULL) return -EINVAL;
  
   	ctx = GET_PMU_CTX();
  
  	if (ctx == NULL) return -EINVAL;
  
  	/*
  	 * for now limit to current task, which is enough when calling
  	 * from overflow handler
  	 */
  	if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
  
  	return pfm_write_ibrs(ctx, req, nreq, regs);
  }
  EXPORT_SYMBOL(pfm_mod_write_ibrs);
  
  int
  pfm_mod_write_dbrs(struct task_struct *task, void *req, unsigned int nreq, struct pt_regs *regs)
  {
  	pfm_context_t *ctx;
  
  	if (req == NULL) return -EINVAL;
  
   	ctx = GET_PMU_CTX();
  
  	if (ctx == NULL) return -EINVAL;
  
  	/*
  	 * for now limit to current task, which is enough when calling
  	 * from overflow handler
  	 */
  	if (task != current && ctx->ctx_fl_system == 0) return -EBUSY;
  
  	return pfm_write_dbrs(ctx, req, nreq, regs);
  }
  EXPORT_SYMBOL(pfm_mod_write_dbrs);
  
  
  static int
  pfm_get_features(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	pfarg_features_t *req = (pfarg_features_t *)arg;
  
  	req->ft_version = PFM_VERSION;
  	return 0;
  }
  
  static int
  pfm_stop(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	struct pt_regs *tregs;
  	struct task_struct *task = PFM_CTX_TASK(ctx);
  	int state, is_system;
  
  	state     = ctx->ctx_state;
  	is_system = ctx->ctx_fl_system;
  
  	/*
  	 * context must be attached to issue the stop command (includes LOADED,MASKED,ZOMBIE)
  	 */
  	if (state == PFM_CTX_UNLOADED) return -EINVAL;
  
  	/*
   	 * In system wide and when the context is loaded, access can only happen
   	 * when the caller is running on the CPU being monitored by the session.
   	 * It does not have to be the owner (ctx_task) of the context per se.
   	 */
  	if (is_system && ctx->ctx_cpu != smp_processor_id()) {
  		DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  		return -EBUSY;
  	}
  	DPRINT(("task [%d] ctx_state=%d is_system=%d
  ",

  		task_pid_nr(PFM_CTX_TASK(ctx)),

  		state,
  		is_system));
  	/*
  	 * in system mode, we need to update the PMU directly
  	 * and the user level state of the caller, which may not
  	 * necessarily be the creator of the context.
  	 */
  	if (is_system) {
  		/*
  		 * Update local PMU first
  		 *
  		 * disable dcr pp
  		 */
  		ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) & ~IA64_DCR_PP);
  		ia64_srlz_i();
  
  		/*
  		 * update local cpuinfo
  		 */
  		PFM_CPUINFO_CLEAR(PFM_CPUINFO_DCR_PP);
  
  		/*
  		 * stop monitoring, does srlz.i
  		 */
  		pfm_clear_psr_pp();
  
  		/*
  		 * stop monitoring in the caller
  		 */
  		ia64_psr(regs)->pp = 0;
  
  		return 0;
  	}
  	/*
  	 * per-task mode
  	 */
  
  	if (task == current) {
  		/* stop monitoring  at kernel level */
  		pfm_clear_psr_up();
  
  		/*
  	 	 * stop monitoring at the user level
  	 	 */
  		ia64_psr(regs)->up = 0;
  	} else {

  		tregs = task_pt_regs(task);

  
  		/*
  	 	 * stop monitoring at the user level
  	 	 */
  		ia64_psr(tregs)->up = 0;
  
  		/*
  		 * monitoring disabled in kernel at next reschedule
  		 */
  		ctx->ctx_saved_psr_up = 0;

  		DPRINT(("task=[%d]
  ", task_pid_nr(task)));

  	}
  	return 0;
  }
  
  
  static int
  pfm_start(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	struct pt_regs *tregs;
  	int state, is_system;
  
  	state     = ctx->ctx_state;
  	is_system = ctx->ctx_fl_system;
  
  	if (state != PFM_CTX_LOADED) return -EINVAL;
  
  	/*
   	 * In system wide and when the context is loaded, access can only happen
   	 * when the caller is running on the CPU being monitored by the session.
   	 * It does not have to be the owner (ctx_task) of the context per se.
   	 */
  	if (is_system && ctx->ctx_cpu != smp_processor_id()) {
  		DPRINT(("should be running on CPU%d
  ", ctx->ctx_cpu));
  		return -EBUSY;
  	}
  
  	/*
  	 * in system mode, we need to update the PMU directly
  	 * and the user level state of the caller, which may not
  	 * necessarily be the creator of the context.
  	 */
  	if (is_system) {
  
  		/*
  		 * set user level psr.pp for the caller
  		 */
  		ia64_psr(regs)->pp = 1;
  
  		/*
  		 * now update the local PMU and cpuinfo
  		 */
  		PFM_CPUINFO_SET(PFM_CPUINFO_DCR_PP);
  
  		/*
  		 * start monitoring at kernel level
  		 */
  		pfm_set_psr_pp();
  
  		/* enable dcr pp */
  		ia64_setreg(_IA64_REG_CR_DCR, ia64_getreg(_IA64_REG_CR_DCR) | IA64_DCR_PP);
  		ia64_srlz_i();
  
  		return 0;
  	}
  
  	/*
  	 * per-process mode
  	 */
  
  	if (ctx->ctx_task == current) {
  
  		/* start monitoring at kernel level */
  		pfm_set_psr_up();
  
  		/*
  		 * activate monitoring at user level
  		 */
  		ia64_psr(regs)->up = 1;
  
  	} else {

  		tregs = task_pt_regs(ctx->ctx_task);

  
  		/*
  		 * start monitoring at the kernel level the next
  		 * time the task is scheduled
  		 */
  		ctx->ctx_saved_psr_up = IA64_PSR_UP;
  
  		/*
  		 * activate monitoring at user level
  		 */
  		ia64_psr(tregs)->up = 1;
  	}
  	return 0;
  }
  
  static int
  pfm_get_pmc_reset(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	pfarg_reg_t *req = (pfarg_reg_t *)arg;
  	unsigned int cnum;
  	int i;
  	int ret = -EINVAL;
  
  	for (i = 0; i < count; i++, req++) {
  
  		cnum = req->reg_num;
  
  		if (!PMC_IS_IMPL(cnum)) goto abort_mission;
  
  		req->reg_value = PMC_DFL_VAL(cnum);
  
  		PFM_REG_RETFLAG_SET(req->reg_flags, 0);
  
  		DPRINT(("pmc_reset_val pmc[%u]=0x%lx
  ", cnum, req->reg_value));
  	}
  	return 0;
  
  abort_mission:
  	PFM_REG_RETFLAG_SET(req->reg_flags, PFM_REG_RETFL_EINVAL);
  	return ret;
  }
  
  static int
  pfm_check_task_exist(pfm_context_t *ctx)
  {
  	struct task_struct *g, *t;
  	int ret = -ESRCH;
  
  	read_lock(&tasklist_lock);
  
  	do_each_thread (g, t) {
  		if (t->thread.pfm_context == ctx) {
  			ret = 0;

  			goto out;

  		}
  	} while_each_thread (g, t);

  out:

  	read_unlock(&tasklist_lock);
  
  	DPRINT(("pfm_check_task_exist: ret=%d ctx=%p
  ", ret, ctx));
  
  	return ret;
  }
  
  static int
  pfm_context_load(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	struct task_struct *task;
  	struct thread_struct *thread;
  	struct pfm_context_t *old;
  	unsigned long flags;
  #ifndef CONFIG_SMP
  	struct task_struct *owner_task = NULL;
  #endif
  	pfarg_load_t *req = (pfarg_load_t *)arg;
  	unsigned long *pmcs_source, *pmds_source;
  	int the_cpu;
  	int ret = 0;
  	int state, is_system, set_dbregs = 0;
  
  	state     = ctx->ctx_state;
  	is_system = ctx->ctx_fl_system;
  	/*
  	 * can only load from unloaded or terminated state
  	 */
  	if (state != PFM_CTX_UNLOADED) {
  		DPRINT(("cannot load to [%d], invalid ctx_state=%d
  ",
  			req->load_pid,
  			ctx->ctx_state));

  		return -EBUSY;

  	}
  
  	DPRINT(("load_pid [%d] using_dbreg=%d
  ", req->load_pid, ctx->ctx_fl_using_dbreg));
  
  	if (CTX_OVFL_NOBLOCK(ctx) == 0 && req->load_pid == current->pid) {
  		DPRINT(("cannot use blocking mode on self
  "));
  		return -EINVAL;
  	}
  
  	ret = pfm_get_task(ctx, req->load_pid, &task);
  	if (ret) {
  		DPRINT(("load_pid [%d] get_task=%d
  ", req->load_pid, ret));
  		return ret;
  	}
  
  	ret = -EINVAL;
  
  	/*
  	 * system wide is self monitoring only
  	 */
  	if (is_system && task != current) {
  		DPRINT(("system wide is self monitoring only load_pid=%d
  ",
  			req->load_pid));
  		goto error;
  	}
  
  	thread = &task->thread;
  
  	ret = 0;
  	/*
  	 * cannot load a context which is using range restrictions,
  	 * into a task that is being debugged.
  	 */
  	if (ctx->ctx_fl_using_dbreg) {
  		if (thread->flags & IA64_THREAD_DBG_VALID) {
  			ret = -EBUSY;
  			DPRINT(("load_pid [%d] task is debugged, cannot load range restrictions
  ", req->load_pid));
  			goto error;
  		}
  		LOCK_PFS(flags);
  
  		if (is_system) {
  			if (pfm_sessions.pfs_ptrace_use_dbregs) {

  				DPRINT(("cannot load [%d] dbregs in use
  ",
  							task_pid_nr(task)));

  				ret = -EBUSY;
  			} else {
  				pfm_sessions.pfs_sys_use_dbregs++;

  				DPRINT(("load [%d] increased sys_use_dbreg=%u
  ", task_pid_nr(task), pfm_sessions.pfs_sys_use_dbregs));

  				set_dbregs = 1;
  			}
  		}
  
  		UNLOCK_PFS(flags);
  
  		if (ret) goto error;
  	}
  
  	/*
  	 * SMP system-wide monitoring implies self-monitoring.
  	 *
  	 * The programming model expects the task to
  	 * be pinned on a CPU throughout the session.
  	 * Here we take note of the current CPU at the
  	 * time the context is loaded. No call from
  	 * another CPU will be allowed.
  	 *
  	 * The pinning via shed_setaffinity()
  	 * must be done by the calling task prior
  	 * to this call.
  	 *
  	 * systemwide: keep track of CPU this session is supposed to run on
  	 */
  	the_cpu = ctx->ctx_cpu = smp_processor_id();
  
  	ret = -EBUSY;
  	/*
  	 * now reserve the session
  	 */
  	ret = pfm_reserve_session(current, is_system, the_cpu);
  	if (ret) goto error;
  
  	/*
  	 * task is necessarily stopped at this point.
  	 *
  	 * If the previous context was zombie, then it got removed in
  	 * pfm_save_regs(). Therefore we should not see it here.
  	 * If we see a context, then this is an active context
  	 *
  	 * XXX: needs to be atomic
  	 */
  	DPRINT(("before cmpxchg() old_ctx=%p new_ctx=%p
  ",
  		thread->pfm_context, ctx));

  	ret = -EBUSY;

  	old = ia64_cmpxchg(acq, &thread->pfm_context, NULL, ctx, sizeof(pfm_context_t *));
  	if (old != NULL) {
  		DPRINT(("load_pid [%d] already has a context
  ", req->load_pid));
  		goto error_unres;
  	}
  
  	pfm_reset_msgq(ctx);
  
  	ctx->ctx_state = PFM_CTX_LOADED;
  
  	/*
  	 * link context to task
  	 */
  	ctx->ctx_task = task;
  
  	if (is_system) {
  		/*
  		 * we load as stopped
  		 */
  		PFM_CPUINFO_SET(PFM_CPUINFO_SYST_WIDE);
  		PFM_CPUINFO_CLEAR(PFM_CPUINFO_DCR_PP);
  
  		if (ctx->ctx_fl_excl_idle) PFM_CPUINFO_SET(PFM_CPUINFO_EXCL_IDLE);
  	} else {
  		thread->flags |= IA64_THREAD_PM_VALID;
  	}
  
  	/*
  	 * propagate into thread-state
  	 */
  	pfm_copy_pmds(task, ctx);
  	pfm_copy_pmcs(task, ctx);

  	pmcs_source = ctx->th_pmcs;
  	pmds_source = ctx->th_pmds;

  
  	/*
  	 * always the case for system-wide
  	 */
  	if (task == current) {
  
  		if (is_system == 0) {
  
  			/* allow user level control */
  			ia64_psr(regs)->sp = 0;

  			DPRINT(("clearing psr.sp for [%d]
  ", task_pid_nr(task)));

  
  			SET_LAST_CPU(ctx, smp_processor_id());
  			INC_ACTIVATION();
  			SET_ACTIVATION(ctx);
  #ifndef CONFIG_SMP
  			/*
  			 * push the other task out, if any
  			 */
  			owner_task = GET_PMU_OWNER();
  			if (owner_task) pfm_lazy_save_regs(owner_task);
  #endif
  		}
  		/*
  		 * load all PMD from ctx to PMU (as opposed to thread state)
  		 * restore all PMC from ctx to PMU
  		 */
  		pfm_restore_pmds(pmds_source, ctx->ctx_all_pmds[0]);
  		pfm_restore_pmcs(pmcs_source, ctx->ctx_all_pmcs[0]);
  
  		ctx->ctx_reload_pmcs[0] = 0UL;
  		ctx->ctx_reload_pmds[0] = 0UL;
  
  		/*
  		 * guaranteed safe by earlier check against DBG_VALID
  		 */
  		if (ctx->ctx_fl_using_dbreg) {
  			pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
  			pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
  		}
  		/*
  		 * set new ownership
  		 */
  		SET_PMU_OWNER(task, ctx);

  		DPRINT(("context loaded on PMU for [%d]
  ", task_pid_nr(task)));

  	} else {
  		/*
  		 * when not current, task MUST be stopped, so this is safe
  		 */

  		regs = task_pt_regs(task);

  
  		/* force a full reload */
  		ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
  		SET_LAST_CPU(ctx, -1);
  
  		/* initial saved psr (stopped) */
  		ctx->ctx_saved_psr_up = 0UL;
  		ia64_psr(regs)->up = ia64_psr(regs)->pp = 0;
  	}
  
  	ret = 0;
  
  error_unres:
  	if (ret) pfm_unreserve_session(ctx, ctx->ctx_fl_system, the_cpu);
  error:
  	/*
  	 * we must undo the dbregs setting (for system-wide)
  	 */
  	if (ret && set_dbregs) {
  		LOCK_PFS(flags);
  		pfm_sessions.pfs_sys_use_dbregs--;
  		UNLOCK_PFS(flags);
  	}
  	/*
  	 * release task, there is now a link with the context
  	 */
  	if (is_system == 0 && task != current) {
  		pfm_put_task(task);
  
  		if (ret == 0) {
  			ret = pfm_check_task_exist(ctx);
  			if (ret) {
  				ctx->ctx_state = PFM_CTX_UNLOADED;
  				ctx->ctx_task  = NULL;
  			}
  		}
  	}
  	return ret;
  }
  
  /*
   * in this function, we do not need to increase the use count
   * for the task via get_task_struct(), because we hold the
   * context lock. If the task were to disappear while having
   * a context attached, it would go through pfm_exit_thread()
   * which also grabs the context lock  and would therefore be blocked
   * until we are here.
   */
  static void pfm_flush_pmds(struct task_struct *, pfm_context_t *ctx);
  
  static int
  pfm_context_unload(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs)
  {
  	struct task_struct *task = PFM_CTX_TASK(ctx);
  	struct pt_regs *tregs;
  	int prev_state, is_system;
  	int ret;

  	DPRINT(("ctx_state=%d task [%d]
  ", ctx->ctx_state, task ? task_pid_nr(task) : -1));

  
  	prev_state = ctx->ctx_state;
  	is_system  = ctx->ctx_fl_system;
  
  	/*
  	 * unload only when necessary
  	 */
  	if (prev_state == PFM_CTX_UNLOADED) {
  		DPRINT(("ctx_state=%d, nothing to do
  ", prev_state));
  		return 0;
  	}
  
  	/*
  	 * clear psr and dcr bits
  	 */
  	ret = pfm_stop(ctx, NULL, 0, regs);
  	if (ret) return ret;
  
  	ctx->ctx_state = PFM_CTX_UNLOADED;
  
  	/*
  	 * in system mode, we need to update the PMU directly
  	 * and the user level state of the caller, which may not
  	 * necessarily be the creator of the context.
  	 */
  	if (is_system) {
  
  		/*
  		 * Update cpuinfo
  		 *
  		 * local PMU is taken care of in pfm_stop()
  		 */
  		PFM_CPUINFO_CLEAR(PFM_CPUINFO_SYST_WIDE);
  		PFM_CPUINFO_CLEAR(PFM_CPUINFO_EXCL_IDLE);
  
  		/*
  		 * save PMDs in context
  		 * release ownership
  		 */
  		pfm_flush_pmds(current, ctx);
  
  		/*
  		 * at this point we are done with the PMU
  		 * so we can unreserve the resource.
  		 */
  		if (prev_state != PFM_CTX_ZOMBIE) 
  			pfm_unreserve_session(ctx, 1 , ctx->ctx_cpu);
  
  		/*
  		 * disconnect context from task
  		 */
  		task->thread.pfm_context = NULL;
  		/*
  		 * disconnect task from context
  		 */
  		ctx->ctx_task = NULL;
  
  		/*
  		 * There is nothing more to cleanup here.
  		 */
  		return 0;
  	}
  
  	/*
  	 * per-task mode
  	 */

  	tregs = task == current ? regs : task_pt_regs(task);

  
  	if (task == current) {
  		/*
  		 * cancel user level control
  		 */
  		ia64_psr(regs)->sp = 1;

  		DPRINT(("setting psr.sp for [%d]
  ", task_pid_nr(task)));

  	}
  	/*
  	 * save PMDs to context
  	 * release ownership
  	 */
  	pfm_flush_pmds(task, ctx);
  
  	/*
  	 * at this point we are done with the PMU
  	 * so we can unreserve the resource.
  	 *
  	 * when state was ZOMBIE, we have already unreserved.
  	 */
  	if (prev_state != PFM_CTX_ZOMBIE) 
  		pfm_unreserve_session(ctx, 0 , ctx->ctx_cpu);
  
  	/*
  	 * reset activation counter and psr
  	 */
  	ctx->ctx_last_activation = PFM_INVALID_ACTIVATION;
  	SET_LAST_CPU(ctx, -1);
  
  	/*
  	 * PMU state will not be restored
  	 */
  	task->thread.flags &= ~IA64_THREAD_PM_VALID;
  
  	/*
  	 * break links between context and task
  	 */
  	task->thread.pfm_context  = NULL;
  	ctx->ctx_task             = NULL;
  
  	PFM_SET_WORK_PENDING(task, 0);
  
  	ctx->ctx_fl_trap_reason  = PFM_TRAP_REASON_NONE;
  	ctx->ctx_fl_can_restart  = 0;
  	ctx->ctx_fl_going_zombie = 0;

  	DPRINT(("disconnected [%d] from context
  ", task_pid_nr(task)));

  
  	return 0;
  }
  
  
  /*
   * called only from exit_thread(): task == current
   * we come here only if current has a context attached (loaded or masked)
   */
  void
  pfm_exit_thread(struct task_struct *task)
  {
  	pfm_context_t *ctx;
  	unsigned long flags;

  	struct pt_regs *regs = task_pt_regs(task);

  	int ret, state;
  	int free_ok = 0;
  
  	ctx = PFM_GET_CTX(task);
  
  	PROTECT_CTX(ctx, flags);

  	DPRINT(("state=%d task [%d]
  ", ctx->ctx_state, task_pid_nr(task)));

  
  	state = ctx->ctx_state;
  	switch(state) {
  		case PFM_CTX_UNLOADED:
  			/*

  	 		 * only comes to this function if pfm_context is not NULL, i.e., cannot

  			 * be in unloaded state
  	 		 */

  			printk(KERN_ERR "perfmon: pfm_exit_thread [%d] ctx unloaded
  ", task_pid_nr(task));

  			break;
  		case PFM_CTX_LOADED:
  		case PFM_CTX_MASKED:
  			ret = pfm_context_unload(ctx, NULL, 0, regs);
  			if (ret) {

  				printk(KERN_ERR "perfmon: pfm_exit_thread [%d] state=%d unload failed %d
  ", task_pid_nr(task), state, ret);

  			}
  			DPRINT(("ctx unloaded for current state was %d
  ", state));
  
  			pfm_end_notify_user(ctx);
  			break;
  		case PFM_CTX_ZOMBIE:
  			ret = pfm_context_unload(ctx, NULL, 0, regs);
  			if (ret) {

  				printk(KERN_ERR "perfmon: pfm_exit_thread [%d] state=%d unload failed %d
  ", task_pid_nr(task), state, ret);

  			}
  			free_ok = 1;
  			break;
  		default:

  			printk(KERN_ERR "perfmon: pfm_exit_thread [%d] unexpected state=%d
  ", task_pid_nr(task), state);

  			break;
  	}
  	UNPROTECT_CTX(ctx, flags);
  
  	{ u64 psr = pfm_get_psr();
  	  BUG_ON(psr & (IA64_PSR_UP|IA64_PSR_PP));
  	  BUG_ON(GET_PMU_OWNER());
  	  BUG_ON(ia64_psr(regs)->up);
  	  BUG_ON(ia64_psr(regs)->pp);
  	}
  
  	/*
  	 * All memory free operations (especially for vmalloc'ed memory)
  	 * MUST be done with interrupts ENABLED.
  	 */
  	if (free_ok) pfm_context_free(ctx);
  }
  
  /*
   * functions MUST be listed in the increasing order of their index (see permfon.h)
   */
  #define PFM_CMD(name, flags, arg_count, arg_type, getsz) { name, #name, flags, arg_count, sizeof(arg_type), getsz }
  #define PFM_CMD_S(name, flags) { name, #name, flags, 0, 0, NULL }
  #define PFM_CMD_PCLRWS	(PFM_CMD_FD|PFM_CMD_ARG_RW|PFM_CMD_STOP)
  #define PFM_CMD_PCLRW	(PFM_CMD_FD|PFM_CMD_ARG_RW)
  #define PFM_CMD_NONE	{ NULL, "no-cmd", 0, 0, 0, NULL}
  
  static pfm_cmd_desc_t pfm_cmd_tab[]={
  /* 0  */PFM_CMD_NONE,
  /* 1  */PFM_CMD(pfm_write_pmcs, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_reg_t, NULL),
  /* 2  */PFM_CMD(pfm_write_pmds, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_reg_t, NULL),
  /* 3  */PFM_CMD(pfm_read_pmds, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_reg_t, NULL),
  /* 4  */PFM_CMD_S(pfm_stop, PFM_CMD_PCLRWS),
  /* 5  */PFM_CMD_S(pfm_start, PFM_CMD_PCLRWS),
  /* 6  */PFM_CMD_NONE,
  /* 7  */PFM_CMD_NONE,
  /* 8  */PFM_CMD(pfm_context_create, PFM_CMD_ARG_RW, 1, pfarg_context_t, pfm_ctx_getsize),
  /* 9  */PFM_CMD_NONE,
  /* 10 */PFM_CMD_S(pfm_restart, PFM_CMD_PCLRW),
  /* 11 */PFM_CMD_NONE,
  /* 12 */PFM_CMD(pfm_get_features, PFM_CMD_ARG_RW, 1, pfarg_features_t, NULL),
  /* 13 */PFM_CMD(pfm_debug, 0, 1, unsigned int, NULL),
  /* 14 */PFM_CMD_NONE,
  /* 15 */PFM_CMD(pfm_get_pmc_reset, PFM_CMD_ARG_RW, PFM_CMD_ARG_MANY, pfarg_reg_t, NULL),
  /* 16 */PFM_CMD(pfm_context_load, PFM_CMD_PCLRWS, 1, pfarg_load_t, NULL),
  /* 17 */PFM_CMD_S(pfm_context_unload, PFM_CMD_PCLRWS),
  /* 18 */PFM_CMD_NONE,
  /* 19 */PFM_CMD_NONE,
  /* 20 */PFM_CMD_NONE,
  /* 21 */PFM_CMD_NONE,
  /* 22 */PFM_CMD_NONE,
  /* 23 */PFM_CMD_NONE,
  /* 24 */PFM_CMD_NONE,
  /* 25 */PFM_CMD_NONE,
  /* 26 */PFM_CMD_NONE,
  /* 27 */PFM_CMD_NONE,
  /* 28 */PFM_CMD_NONE,
  /* 29 */PFM_CMD_NONE,
  /* 30 */PFM_CMD_NONE,
  /* 31 */PFM_CMD_NONE,
  /* 32 */PFM_CMD(pfm_write_ibrs, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_dbreg_t, NULL),
  /* 33 */PFM_CMD(pfm_write_dbrs, PFM_CMD_PCLRWS, PFM_CMD_ARG_MANY, pfarg_dbreg_t, NULL)
  };
  #define PFM_CMD_COUNT	(sizeof(pfm_cmd_tab)/sizeof(pfm_cmd_desc_t))
  
  static int
  pfm_check_task_state(pfm_context_t *ctx, int cmd, unsigned long flags)
  {
  	struct task_struct *task;
  	int state, old_state;
  
  recheck:
  	state = ctx->ctx_state;
  	task  = ctx->ctx_task;
  
  	if (task == NULL) {
  		DPRINT(("context %d no task, state=%d
  ", ctx->ctx_fd, state));
  		return 0;
  	}
  
  	DPRINT(("context %d state=%d [%d] task_state=%ld must_stop=%d
  ",
  		ctx->ctx_fd,
  		state,

  		task_pid_nr(task),

  		task->state, PFM_CMD_STOPPED(cmd)));
  
  	/*
  	 * self-monitoring always ok.
  	 *
  	 * for system-wide the caller can either be the creator of the
  	 * context (to one to which the context is attached to) OR
  	 * a task running on the same CPU as the session.
  	 */
  	if (task == current || ctx->ctx_fl_system) return 0;
  
  	/*

  	 * we are monitoring another thread

  	 */

  	switch(state) {
  		case PFM_CTX_UNLOADED:
  			/*
  			 * if context is UNLOADED we are safe to go
  			 */
  			return 0;
  		case PFM_CTX_ZOMBIE:
  			/*
  			 * no command can operate on a zombie context
  			 */
  			DPRINT(("cmd %d state zombie cannot operate on context
  ", cmd));
  			return -EINVAL;
  		case PFM_CTX_MASKED:
  			/*
  			 * PMU state has been saved to software even though
  			 * the thread may still be running.
  			 */
  			if (cmd != PFM_UNLOAD_CONTEXT) return 0;

  	}
  
  	/*
  	 * context is LOADED or MASKED. Some commands may need to have 
  	 * the task stopped.
  	 *
  	 * We could lift this restriction for UP but it would mean that
  	 * the user has no guarantee the task would not run between
  	 * two successive calls to perfmonctl(). That's probably OK.
  	 * If this user wants to ensure the task does not run, then
  	 * the task must be stopped.
  	 */
  	if (PFM_CMD_STOPPED(cmd)) {

  		if (!task_is_stopped_or_traced(task)) {

  			DPRINT(("[%d] task not in stopped state
  ", task_pid_nr(task)));

  			return -EBUSY;
  		}
  		/*
  		 * task is now stopped, wait for ctxsw out
  		 *
  		 * This is an interesting point in the code.
  		 * We need to unprotect the context because
  		 * the pfm_save_regs() routines needs to grab
  		 * the same lock. There are danger in doing
  		 * this because it leaves a window open for
  		 * another task to get access to the context
  		 * and possibly change its state. The one thing
  		 * that is not possible is for the context to disappear
  		 * because we are protected by the VFS layer, i.e.,
  		 * get_fd()/put_fd().
  		 */
  		old_state = state;
  
  		UNPROTECT_CTX(ctx, flags);

  		wait_task_inactive(task, 0);

  
  		PROTECT_CTX(ctx, flags);
  
  		/*
  		 * we must recheck to verify if state has changed
  		 */
  		if (ctx->ctx_state != old_state) {
  			DPRINT(("old_state=%d new_state=%d
  ", old_state, ctx->ctx_state));
  			goto recheck;
  		}
  	}
  	return 0;
  }
  
  /*
   * system-call entry point (must return long)
   */
  asmlinkage long
  sys_perfmonctl (int fd, int cmd, void __user *arg, int count)
  {
  	struct file *file = NULL;
  	pfm_context_t *ctx = NULL;
  	unsigned long flags = 0UL;
  	void *args_k = NULL;
  	long ret; /* will expand int return types */
  	size_t base_sz, sz, xtra_sz = 0;
  	int narg, completed_args = 0, call_made = 0, cmd_flags;
  	int (*func)(pfm_context_t *ctx, void *arg, int count, struct pt_regs *regs);
  	int (*getsize)(void *arg, size_t *sz);
  #define PFM_MAX_ARGSIZE	4096
  
  	/*
  	 * reject any call if perfmon was disabled at initialization
  	 */
  	if (unlikely(pmu_conf == NULL)) return -ENOSYS;
  
  	if (unlikely(cmd < 0 || cmd >= PFM_CMD_COUNT)) {
  		DPRINT(("invalid cmd=%d
  ", cmd));
  		return -EINVAL;
  	}
  
  	func      = pfm_cmd_tab[cmd].cmd_func;
  	narg      = pfm_cmd_tab[cmd].cmd_narg;
  	base_sz   = pfm_cmd_tab[cmd].cmd_argsize;
  	getsize   = pfm_cmd_tab[cmd].cmd_getsize;
  	cmd_flags = pfm_cmd_tab[cmd].cmd_flags;
  
  	if (unlikely(func == NULL)) {
  		DPRINT(("invalid cmd=%d
  ", cmd));
  		return -EINVAL;
  	}
  
  	DPRINT(("cmd=%s idx=%d narg=0x%x argsz=%lu count=%d
  ",
  		PFM_CMD_NAME(cmd),
  		cmd,
  		narg,
  		base_sz,
  		count));
  
  	/*
  	 * check if number of arguments matches what the command expects
  	 */
  	if (unlikely((narg == PFM_CMD_ARG_MANY && count <= 0) || (narg > 0 && narg != count)))
  		return -EINVAL;
  
  restart_args:
  	sz = xtra_sz + base_sz*count;
  	/*
  	 * limit abuse to min page size
  	 */
  	if (unlikely(sz > PFM_MAX_ARGSIZE)) {

  		printk(KERN_ERR "perfmon: [%d] argument too big %lu
  ", task_pid_nr(current), sz);

  		return -E2BIG;
  	}
  
  	/*
  	 * allocate default-sized argument buffer
  	 */
  	if (likely(count && args_k == NULL)) {
  		args_k = kmalloc(PFM_MAX_ARGSIZE, GFP_KERNEL);
  		if (args_k == NULL) return -ENOMEM;
  	}
  
  	ret = -EFAULT;
  
  	/*
  	 * copy arguments
  	 *
  	 * assume sz = 0 for command without parameters
  	 */
  	if (sz && copy_from_user(args_k, arg, sz)) {
  		DPRINT(("cannot copy_from_user %lu bytes @%p
  ", sz, arg));
  		goto error_args;
  	}
  
  	/*
  	 * check if command supports extra parameters
  	 */
  	if (completed_args == 0 && getsize) {
  		/*
  		 * get extra parameters size (based on main argument)
  		 */
  		ret = (*getsize)(args_k, &xtra_sz);
  		if (ret) goto error_args;
  
  		completed_args = 1;
  
  		DPRINT(("restart_args sz=%lu xtra_sz=%lu
  ", sz, xtra_sz));
  
  		/* retry if necessary */
  		if (likely(xtra_sz)) goto restart_args;
  	}
  
  	if (unlikely((cmd_flags & PFM_CMD_FD) == 0)) goto skip_fd;
  
  	ret = -EBADF;
  
  	file = fget(fd);
  	if (unlikely(file == NULL)) {
  		DPRINT(("invalid fd %d
  ", fd));
  		goto error_args;
  	}
  	if (unlikely(PFM_IS_FILE(file) == 0)) {
  		DPRINT(("fd %d not related to perfmon
  ", fd));
  		goto error_args;
  	}

  	ctx = file->private_data;

  	if (unlikely(ctx == NULL)) {
  		DPRINT(("no context for fd %d
  ", fd));
  		goto error_args;
  	}
  	prefetch(&ctx->ctx_state);
  
  	PROTECT_CTX(ctx, flags);
  
  	/*
  	 * check task is stopped
  	 */
  	ret = pfm_check_task_state(ctx, cmd, flags);
  	if (unlikely(ret)) goto abort_locked;
  
  skip_fd:

  	ret = (*func)(ctx, args_k, count, task_pt_regs(current));

  
  	call_made = 1;
  
  abort_locked:
  	if (likely(ctx)) {
  		DPRINT(("context unlocked
  "));
  		UNPROTECT_CTX(ctx, flags);

  	}
  
  	/* copy argument back to user, if needed */
  	if (call_made && PFM_CMD_RW_ARG(cmd) && copy_to_user(arg, args_k, base_sz*count)) ret = -EFAULT;
  
  error_args:

  	if (file)
  		fput(file);

  	kfree(args_k);

  
  	DPRINT(("cmd=%s ret=%ld
  ", PFM_CMD_NAME(cmd), ret));
  
  	return ret;
  }
  
  static void
  pfm_resume_after_ovfl(pfm_context_t *ctx, unsigned long ovfl_regs, struct pt_regs *regs)
  {
  	pfm_buffer_fmt_t *fmt = ctx->ctx_buf_fmt;
  	pfm_ovfl_ctrl_t rst_ctrl;
  	int state;
  	int ret = 0;
  
  	state = ctx->ctx_state;
  	/*
  	 * Unlock sampling buffer and reset index atomically
  	 * XXX: not really needed when blocking
  	 */
  	if (CTX_HAS_SMPL(ctx)) {
  
  		rst_ctrl.bits.mask_monitoring = 0;
  		rst_ctrl.bits.reset_ovfl_pmds = 0;
  
  		if (state == PFM_CTX_LOADED)
  			ret = pfm_buf_fmt_restart_active(fmt, current, &rst_ctrl, ctx->ctx_smpl_hdr, regs);
  		else
  			ret = pfm_buf_fmt_restart(fmt, current, &rst_ctrl, ctx->ctx_smpl_hdr, regs);
  	} else {
  		rst_ctrl.bits.mask_monitoring = 0;
  		rst_ctrl.bits.reset_ovfl_pmds = 1;
  	}
  
  	if (ret == 0) {
  		if (rst_ctrl.bits.reset_ovfl_pmds) {
  			pfm_reset_regs(ctx, &ovfl_regs, PFM_PMD_LONG_RESET);
  		}
  		if (rst_ctrl.bits.mask_monitoring == 0) {
  			DPRINT(("resuming monitoring
  "));
  			if (ctx->ctx_state == PFM_CTX_MASKED) pfm_restore_monitoring(current);
  		} else {
  			DPRINT(("stopping monitoring
  "));
  			//pfm_stop_monitoring(current, regs);
  		}
  		ctx->ctx_state = PFM_CTX_LOADED;
  	}
  }
  
  /*
   * context MUST BE LOCKED when calling
   * can only be called for current
   */
  static void
  pfm_context_force_terminate(pfm_context_t *ctx, struct pt_regs *regs)
  {
  	int ret;

  	DPRINT(("entering for [%d]
  ", task_pid_nr(current)));

  
  	ret = pfm_context_unload(ctx, NULL, 0, regs);
  	if (ret) {

  		printk(KERN_ERR "pfm_context_force_terminate: [%d] unloaded failed with %d
  ", task_pid_nr(current), ret);

  	}
  
  	/*
  	 * and wakeup controlling task, indicating we are now disconnected
  	 */
  	wake_up_interruptible(&ctx->ctx_zombieq);
  
  	/*
  	 * given that context is still locked, the controlling
  	 * task will only get access when we return from
  	 * pfm_handle_work().
  	 */
  }
  
  static int pfm_ovfl_notify_user(pfm_context_t *ctx, unsigned long ovfl_pmds);

   /*
    * pfm_handle_work() can be called with interrupts enabled
    * (TIF_NEED_RESCHED) or disabled. The down_interruptible
    * call may sleep, therefore we must re-enable interrupts
    * to avoid deadlocks. It is safe to do so because this function

    * is called ONLY when returning to user level (pUStk=1), in which case

    * there is no risk of kernel stack overflow due to deep
    * interrupt nesting.
    */

  void
  pfm_handle_work(void)
  {
  	pfm_context_t *ctx;
  	struct pt_regs *regs;

  	unsigned long flags, dummy_flags;

  	unsigned long ovfl_regs;
  	unsigned int reason;
  	int ret;
  
  	ctx = PFM_GET_CTX(current);
  	if (ctx == NULL) {

  		printk(KERN_ERR "perfmon: [%d] has no PFM context
  ",
  			task_pid_nr(current));

  		return;
  	}
  
  	PROTECT_CTX(ctx, flags);
  
  	PFM_SET_WORK_PENDING(current, 0);

  	regs = task_pt_regs(current);

  
  	/*
  	 * extract reason for being here and clear
  	 */
  	reason = ctx->ctx_fl_trap_reason;
  	ctx->ctx_fl_trap_reason = PFM_TRAP_REASON_NONE;
  	ovfl_regs = ctx->ctx_ovfl_regs[0];
  
  	DPRINT(("reason=%d state=%d
  ", reason, ctx->ctx_state));
  
  	/*
  	 * must be done before we check for simple-reset mode
  	 */

  	if (ctx->ctx_fl_going_zombie || ctx->ctx_state == PFM_CTX_ZOMBIE)
  		goto do_zombie;

  
  	//if (CTX_OVFL_NOBLOCK(ctx)) goto skip_blocking;

  	if (reason == PFM_TRAP_REASON_RESET)
  		goto skip_blocking;

  	/*
  	 * restore interrupt mask to what it was on entry.
  	 * Could be enabled/diasbled.
  	 */

  	UNPROTECT_CTX(ctx, flags);

  	/*
  	 * force interrupt enable because of down_interruptible()
  	 */

  	local_irq_enable();
  
  	DPRINT(("before block sleeping
  "));
  
  	/*
  	 * may go through without blocking on SMP systems
  	 * if restart has been received already by the time we call down()
  	 */

  	ret = wait_for_completion_interruptible(&ctx->ctx_restart_done);

  
  	DPRINT(("after block sleeping ret=%d
  ", ret));
  
  	/*

  	 * lock context and mask interrupts again
  	 * We save flags into a dummy because we may have
  	 * altered interrupts mask compared to entry in this
  	 * function.

  	 */

  	PROTECT_CTX(ctx, dummy_flags);

  
  	/*
  	 * we need to read the ovfl_regs only after wake-up
  	 * because we may have had pfm_write_pmds() in between
  	 * and that can changed PMD values and therefore 
  	 * ovfl_regs is reset for these new PMD values.
  	 */
  	ovfl_regs = ctx->ctx_ovfl_regs[0];
  
  	if (ctx->ctx_fl_going_zombie) {
  do_zombie:
  		DPRINT(("context is zombie, bailing out
  "));
  		pfm_context_force_terminate(ctx, regs);
  		goto nothing_to_do;
  	}
  	/*
  	 * in case of interruption of down() we don't restart anything
  	 */

  	if (ret < 0)
  		goto nothing_to_do;

  
  skip_blocking:
  	pfm_resume_after_ovfl(ctx, ovfl_regs, regs);
  	ctx->ctx_ovfl_regs[0] = 0UL;
  
  nothing_to_do:

  	/*
  	 * restore flags as they were upon entry
  	 */

  	UNPROTECT_CTX(ctx, flags);
  }
  
  static int
  pfm_notify_user(pfm_context_t *ctx, pfm_msg_t *msg)
  {
  	if (ctx->ctx_state == PFM_CTX_ZOMBIE) {
  		DPRINT(("ignoring overflow notification, owner is zombie
  "));
  		return 0;
  	}
  
  	DPRINT(("waking up somebody
  "));
  
  	if (msg) wake_up_interruptible(&ctx->ctx_msgq_wait);
  
  	/*
  	 * safe, we are not in intr handler, nor in ctxsw when
  	 * we come here
  	 */
  	kill_fasync (&ctx->ctx_async_queue, SIGIO, POLL_IN);
  
  	return 0;
  }
  
  static int
  pfm_ovfl_notify_user(pfm_context_t *ctx, unsigned long ovfl_pmds)
  {
  	pfm_msg_t *msg = NULL;
  
  	if (ctx->ctx_fl_no_msg == 0) {
  		msg = pfm_get_new_msg(ctx);
  		if (msg == NULL) {
  			printk(KERN_ERR "perfmon: pfm_ovfl_notify_user no more notification msgs
  ");
  			return -1;
  		}
  
  		msg->pfm_ovfl_msg.msg_type         = PFM_MSG_OVFL;
  		msg->pfm_ovfl_msg.msg_ctx_fd       = ctx->ctx_fd;
  		msg->pfm_ovfl_msg.msg_active_set   = 0;
  		msg->pfm_ovfl_msg.msg_ovfl_pmds[0] = ovfl_pmds;
  		msg->pfm_ovfl_msg.msg_ovfl_pmds[1] = 0UL;
  		msg->pfm_ovfl_msg.msg_ovfl_pmds[2] = 0UL;
  		msg->pfm_ovfl_msg.msg_ovfl_pmds[3] = 0UL;
  		msg->pfm_ovfl_msg.msg_tstamp       = 0UL;
  	}
  
  	DPRINT(("ovfl msg: msg=%p no_msg=%d fd=%d ovfl_pmds=0x%lx
  ",
  		msg,
  		ctx->ctx_fl_no_msg,
  		ctx->ctx_fd,
  		ovfl_pmds));
  
  	return pfm_notify_user(ctx, msg);
  }
  
  static int
  pfm_end_notify_user(pfm_context_t *ctx)
  {
  	pfm_msg_t *msg;
  
  	msg = pfm_get_new_msg(ctx);
  	if (msg == NULL) {
  		printk(KERN_ERR "perfmon: pfm_end_notify_user no more notification msgs
  ");
  		return -1;
  	}
  	/* no leak */
  	memset(msg, 0, sizeof(*msg));
  
  	msg->pfm_end_msg.msg_type    = PFM_MSG_END;
  	msg->pfm_end_msg.msg_ctx_fd  = ctx->ctx_fd;
  	msg->pfm_ovfl_msg.msg_tstamp = 0UL;
  
  	DPRINT(("end msg: msg=%p no_msg=%d ctx_fd=%d
  ",
  		msg,
  		ctx->ctx_fl_no_msg,
  		ctx->ctx_fd));
  
  	return pfm_notify_user(ctx, msg);
  }
  
  /*
   * main overflow processing routine.

   * it can be called from the interrupt path or explicitly during the context switch code

   */

  static void pfm_overflow_handler(struct task_struct *task, pfm_context_t *ctx,
  				unsigned long pmc0, struct pt_regs *regs)

  {
  	pfm_ovfl_arg_t *ovfl_arg;
  	unsigned long mask;
  	unsigned long old_val, ovfl_val, new_val;
  	unsigned long ovfl_notify = 0UL, ovfl_pmds = 0UL, smpl_pmds = 0UL, reset_pmds;
  	unsigned long tstamp;
  	pfm_ovfl_ctrl_t	ovfl_ctrl;
  	unsigned int i, has_smpl;
  	int must_notify = 0;
  
  	if (unlikely(ctx->ctx_state == PFM_CTX_ZOMBIE)) goto stop_monitoring;
  
  	/*
  	 * sanity test. Should never happen
  	 */
  	if (unlikely((pmc0 & 0x1) == 0)) goto sanity_check;
  
  	tstamp   = ia64_get_itc();
  	mask     = pmc0 >> PMU_FIRST_COUNTER;
  	ovfl_val = pmu_conf->ovfl_val;
  	has_smpl = CTX_HAS_SMPL(ctx);
  
  	DPRINT_ovfl(("pmc0=0x%lx pid=%d iip=0x%lx, %s "
  		     "used_pmds=0x%lx
  ",
  			pmc0,

  			task ? task_pid_nr(task): -1,

  			(regs ? regs->cr_iip : 0),
  			CTX_OVFL_NOBLOCK(ctx) ? "nonblocking" : "blocking",
  			ctx->ctx_used_pmds[0]));
  
  
  	/*
  	 * first we update the virtual counters
  	 * assume there was a prior ia64_srlz_d() issued
  	 */
  	for (i = PMU_FIRST_COUNTER; mask ; i++, mask >>= 1) {
  
  		/* skip pmd which did not overflow */
  		if ((mask & 0x1) == 0) continue;
  
  		/*
  		 * Note that the pmd is not necessarily 0 at this point as qualified events
  		 * may have happened before the PMU was frozen. The residual count is not
  		 * taken into consideration here but will be with any read of the pmd via
  		 * pfm_read_pmds().
  		 */
  		old_val              = new_val = ctx->ctx_pmds[i].val;
  		new_val             += 1 + ovfl_val;
  		ctx->ctx_pmds[i].val = new_val;
  
  		/*
  		 * check for overflow condition
  		 */
  		if (likely(old_val > new_val)) {
  			ovfl_pmds |= 1UL << i;
  			if (PMC_OVFL_NOTIFY(ctx, i)) ovfl_notify |= 1UL << i;
  		}
  
  		DPRINT_ovfl(("ctx_pmd[%d].val=0x%lx old_val=0x%lx pmd=0x%lx ovfl_pmds=0x%lx ovfl_notify=0x%lx
  ",
  			i,
  			new_val,
  			old_val,
  			ia64_get_pmd(i) & ovfl_val,
  			ovfl_pmds,
  			ovfl_notify));
  	}
  
  	/*
  	 * there was no 64-bit overflow, nothing else to do
  	 */
  	if (ovfl_pmds == 0UL) return;
  
  	/* 
  	 * reset all control bits
  	 */
  	ovfl_ctrl.val = 0;
  	reset_pmds    = 0UL;
  
  	/*
  	 * if a sampling format module exists, then we "cache" the overflow by 
  	 * calling the module's handler() routine.
  	 */
  	if (has_smpl) {
  		unsigned long start_cycles, end_cycles;
  		unsigned long pmd_mask;
  		int j, k, ret = 0;
  		int this_cpu = smp_processor_id();
  
  		pmd_mask = ovfl_pmds >> PMU_FIRST_COUNTER;
  		ovfl_arg = &ctx->ctx_ovfl_arg;
  
  		prefetch(ctx->ctx_smpl_hdr);
  
  		for(i=PMU_FIRST_COUNTER; pmd_mask && ret == 0; i++, pmd_mask >>=1) {
  
  			mask = 1UL << i;
  
  			if ((pmd_mask & 0x1) == 0) continue;
  
  			ovfl_arg->ovfl_pmd      = (unsigned char )i;
  			ovfl_arg->ovfl_notify   = ovfl_notify & mask ? 1 : 0;
  			ovfl_arg->active_set    = 0;
  			ovfl_arg->ovfl_ctrl.val = 0; /* module must fill in all fields */
  			ovfl_arg->smpl_pmds[0]  = smpl_pmds = ctx->ctx_pmds[i].smpl_pmds[0];
  
  			ovfl_arg->pmd_value      = ctx->ctx_pmds[i].val;
  			ovfl_arg->pmd_last_reset = ctx->ctx_pmds[i].lval;
  			ovfl_arg->pmd_eventid    = ctx->ctx_pmds[i].eventid;
  
  			/*
  		 	 * copy values of pmds of interest. Sampling format may copy them
  		 	 * into sampling buffer.
  		 	 */
  			if (smpl_pmds) {
  				for(j=0, k=0; smpl_pmds; j++, smpl_pmds >>=1) {
  					if ((smpl_pmds & 0x1) == 0) continue;
  					ovfl_arg->smpl_pmds_values[k++] = PMD_IS_COUNTING(j) ?  pfm_read_soft_counter(ctx, j) : ia64_get_pmd(j);
  					DPRINT_ovfl(("smpl_pmd[%d]=pmd%u=0x%lx
  ", k-1, j, ovfl_arg->smpl_pmds_values[k-1]));
  				}
  			}
  
  			pfm_stats[this_cpu].pfm_smpl_handler_calls++;
  
  			start_cycles = ia64_get_itc();
  
  			/*
  		 	 * call custom buffer format record (handler) routine
  		 	 */
  			ret = (*ctx->ctx_buf_fmt->fmt_handler)(task, ctx->ctx_smpl_hdr, ovfl_arg, regs, tstamp);
  
  			end_cycles = ia64_get_itc();
  
  			/*
  			 * For those controls, we take the union because they have
  			 * an all or nothing behavior.
  			 */
  			ovfl_ctrl.bits.notify_user     |= ovfl_arg->ovfl_ctrl.bits.notify_user;
  			ovfl_ctrl.bits.block_task      |= ovfl_arg->ovfl_ctrl.bits.block_task;
  			ovfl_ctrl.bits.mask_monitoring |= ovfl_arg->ovfl_ctrl.bits.mask_monitoring;
  			/*
  			 * build the bitmask of pmds to reset now
  			 */
  			if (ovfl_arg->ovfl_ctrl.bits.reset_ovfl_pmds) reset_pmds |= mask;
  
  			pfm_stats[this_cpu].pfm_smpl_handler_cycles += end_cycles - start_cycles;
  		}
  		/*
  		 * when the module cannot handle the rest of the overflows, we abort right here
  		 */
  		if (ret && pmd_mask) {
  			DPRINT(("handler aborts leftover ovfl_pmds=0x%lx
  ",
  				pmd_mask<<PMU_FIRST_COUNTER));
  		}
  		/*
  		 * remove the pmds we reset now from the set of pmds to reset in pfm_restart()
  		 */
  		ovfl_pmds &= ~reset_pmds;
  	} else {
  		/*
  		 * when no sampling module is used, then the default
  		 * is to notify on overflow if requested by user
  		 */
  		ovfl_ctrl.bits.notify_user     = ovfl_notify ? 1 : 0;
  		ovfl_ctrl.bits.block_task      = ovfl_notify ? 1 : 0;
  		ovfl_ctrl.bits.mask_monitoring = ovfl_notify ? 1 : 0; /* XXX: change for saturation */
  		ovfl_ctrl.bits.reset_ovfl_pmds = ovfl_notify ? 0 : 1;
  		/*
  		 * if needed, we reset all overflowed pmds
  		 */
  		if (ovfl_notify == 0) reset_pmds = ovfl_pmds;
  	}
  
  	DPRINT_ovfl(("ovfl_pmds=0x%lx reset_pmds=0x%lx
  ", ovfl_pmds, reset_pmds));
  
  	/*
  	 * reset the requested PMD registers using the short reset values
  	 */
  	if (reset_pmds) {
  		unsigned long bm = reset_pmds;
  		pfm_reset_regs(ctx, &bm, PFM_PMD_SHORT_RESET);
  	}
  
  	if (ovfl_notify && ovfl_ctrl.bits.notify_user) {
  		/*
  		 * keep track of what to reset when unblocking
  		 */
  		ctx->ctx_ovfl_regs[0] = ovfl_pmds;
  
  		/*
  		 * check for blocking context 
  		 */
  		if (CTX_OVFL_NOBLOCK(ctx) == 0 && ovfl_ctrl.bits.block_task) {
  
  			ctx->ctx_fl_trap_reason = PFM_TRAP_REASON_BLOCK;
  
  			/*
  			 * set the perfmon specific checking pending work for the task
  			 */
  			PFM_SET_WORK_PENDING(task, 1);
  
  			/*
  			 * when coming from ctxsw, current still points to the
  			 * previous task, therefore we must work with task and not current.
  			 */

  			set_notify_resume(task);

  		}
  		/*
  		 * defer until state is changed (shorten spin window). the context is locked
  		 * anyway, so the signal receiver would come spin for nothing.
  		 */
  		must_notify = 1;
  	}
  
  	DPRINT_ovfl(("owner [%d] pending=%ld reason=%u ovfl_pmds=0x%lx ovfl_notify=0x%lx masked=%d
  ",

  			GET_PMU_OWNER() ? task_pid_nr(GET_PMU_OWNER()) : -1,

  			PFM_GET_WORK_PENDING(task),
  			ctx->ctx_fl_trap_reason,
  			ovfl_pmds,
  			ovfl_notify,
  			ovfl_ctrl.bits.mask_monitoring ? 1 : 0));
  	/*
  	 * in case monitoring must be stopped, we toggle the psr bits
  	 */
  	if (ovfl_ctrl.bits.mask_monitoring) {
  		pfm_mask_monitoring(task);
  		ctx->ctx_state = PFM_CTX_MASKED;
  		ctx->ctx_fl_can_restart = 1;
  	}
  
  	/*
  	 * send notification now
  	 */
  	if (must_notify) pfm_ovfl_notify_user(ctx, ovfl_notify);
  
  	return;
  
  sanity_check:
  	printk(KERN_ERR "perfmon: CPU%d overflow handler [%d] pmc0=0x%lx
  ",
  			smp_processor_id(),

  			task ? task_pid_nr(task) : -1,

  			pmc0);
  	return;
  
  stop_monitoring:
  	/*
  	 * in SMP, zombie context is never restored but reclaimed in pfm_load_regs().
  	 * Moreover, zombies are also reclaimed in pfm_save_regs(). Therefore we can
  	 * come here as zombie only if the task is the current task. In which case, we
  	 * can access the PMU  hardware directly.
  	 *
  	 * Note that zombies do have PM_VALID set. So here we do the minimal.
  	 *
  	 * In case the context was zombified it could not be reclaimed at the time
  	 * the monitoring program exited. At this point, the PMU reservation has been
  	 * returned, the sampiing buffer has been freed. We must convert this call
  	 * into a spurious interrupt. However, we must also avoid infinite overflows
  	 * by stopping monitoring for this task. We can only come here for a per-task
  	 * context. All we need to do is to stop monitoring using the psr bits which
  	 * are always task private. By re-enabling secure montioring, we ensure that
  	 * the monitored task will not be able to re-activate monitoring.
  	 * The task will eventually be context switched out, at which point the context
  	 * will be reclaimed (that includes releasing ownership of the PMU).
  	 *
  	 * So there might be a window of time where the number of per-task session is zero
  	 * yet one PMU might have a owner and get at most one overflow interrupt for a zombie
  	 * context. This is safe because if a per-task session comes in, it will push this one
  	 * out and by the virtue on pfm_save_regs(), this one will disappear. If a system wide
  	 * session is force on that CPU, given that we use task pinning, pfm_save_regs() will
  	 * also push our zombie context out.
  	 *
  	 * Overall pretty hairy stuff....
  	 */

  	DPRINT(("ctx is zombie for [%d], converted to spurious
  ", task ? task_pid_nr(task): -1));

  	pfm_clear_psr_up();
  	ia64_psr(regs)->up = 0;
  	ia64_psr(regs)->sp = 1;
  	return;
  }
  
  static int

  pfm_do_interrupt_handler(void *arg, struct pt_regs *regs)

  {
  	struct task_struct *task;
  	pfm_context_t *ctx;
  	unsigned long flags;
  	u64 pmc0;
  	int this_cpu = smp_processor_id();
  	int retval = 0;
  
  	pfm_stats[this_cpu].pfm_ovfl_intr_count++;
  
  	/*
  	 * srlz.d done before arriving here
  	 */
  	pmc0 = ia64_get_pmc(0);
  
  	task = GET_PMU_OWNER();
  	ctx  = GET_PMU_CTX();
  
  	/*
  	 * if we have some pending bits set
  	 * assumes : if any PMC0.bit[63-1] is set, then PMC0.fr = 1
  	 */
  	if (PMC0_HAS_OVFL(pmc0) && task) {
  		/*
  		 * we assume that pmc0.fr is always set here
  		 */
  
  		/* sanity check */
  		if (!ctx) goto report_spurious1;
  
  		if (ctx->ctx_fl_system == 0 && (task->thread.flags & IA64_THREAD_PM_VALID) == 0) 
  			goto report_spurious2;
  
  		PROTECT_CTX_NOPRINT(ctx, flags);
  
  		pfm_overflow_handler(task, ctx, pmc0, regs);
  
  		UNPROTECT_CTX_NOPRINT(ctx, flags);
  
  	} else {
  		pfm_stats[this_cpu].pfm_spurious_ovfl_intr_count++;
  		retval = -1;
  	}
  	/*
  	 * keep it unfrozen at all times
  	 */
  	pfm_unfreeze_pmu();
  
  	return retval;
  
  report_spurious1:
  	printk(KERN_INFO "perfmon: spurious overflow interrupt on CPU%d: process %d has no PFM context
  ",

  		this_cpu, task_pid_nr(task));

  	pfm_unfreeze_pmu();
  	return -1;
  report_spurious2:
  	printk(KERN_INFO "perfmon: spurious overflow interrupt on CPU%d: process %d, invalid flag
  ", 
  		this_cpu, 

  		task_pid_nr(task));

  	pfm_unfreeze_pmu();
  	return -1;
  }
  
  static irqreturn_t

  pfm_interrupt_handler(int irq, void *arg)

  {
  	unsigned long start_cycles, total_cycles;
  	unsigned long min, max;
  	int this_cpu;
  	int ret;

  	struct pt_regs *regs = get_irq_regs();

  
  	this_cpu = get_cpu();

  	if (likely(!pfm_alt_intr_handler)) {
  		min = pfm_stats[this_cpu].pfm_ovfl_intr_cycles_min;
  		max = pfm_stats[this_cpu].pfm_ovfl_intr_cycles_max;

  		start_cycles = ia64_get_itc();

  		ret = pfm_do_interrupt_handler(arg, regs);

  		total_cycles = ia64_get_itc();

  		/*
  		 * don't measure spurious interrupts
  		 */
  		if (likely(ret == 0)) {
  			total_cycles -= start_cycles;

  			if (total_cycles < min) pfm_stats[this_cpu].pfm_ovfl_intr_cycles_min = total_cycles;
  			if (total_cycles > max) pfm_stats[this_cpu].pfm_ovfl_intr_cycles_max = total_cycles;

  			pfm_stats[this_cpu].pfm_ovfl_intr_cycles += total_cycles;
  		}
  	}
  	else {
  		(*pfm_alt_intr_handler->handler)(irq, arg, regs);

  	}

  	put_cpu();

  	return IRQ_HANDLED;
  }
  
  /*
   * /proc/perfmon interface, for debug only
   */

  #define PFM_PROC_SHOW_HEADER	((void *)(long)nr_cpu_ids+1)

  
  static void *
  pfm_proc_start(struct seq_file *m, loff_t *pos)
  {
  	if (*pos == 0) {
  		return PFM_PROC_SHOW_HEADER;
  	}

  	while (*pos <= nr_cpu_ids) {

  		if (cpu_online(*pos - 1)) {
  			return (void *)*pos;
  		}
  		++*pos;
  	}
  	return NULL;
  }
  
  static void *
  pfm_proc_next(struct seq_file *m, void *v, loff_t *pos)
  {
  	++*pos;
  	return pfm_proc_start(m, pos);
  }
  
  static void
  pfm_proc_stop(struct seq_file *m, void *v)
  {
  }
  
  static void
  pfm_proc_show_header(struct seq_file *m)
  {
  	struct list_head * pos;
  	pfm_buffer_fmt_t * entry;
  	unsigned long flags;
  
   	seq_printf(m,
  		"perfmon version           : %u.%u
  "
  		"model                     : %s
  "
  		"fastctxsw                 : %s
  "
  		"expert mode               : %s
  "
  		"ovfl_mask                 : 0x%lx
  "
  		"PMU flags                 : 0x%x
  ",
  		PFM_VERSION_MAJ, PFM_VERSION_MIN,
  		pmu_conf->pmu_name,
  		pfm_sysctl.fastctxsw > 0 ? "Yes": "No",
  		pfm_sysctl.expert_mode > 0 ? "Yes": "No",
  		pmu_conf->ovfl_val,
  		pmu_conf->flags);
  
    	LOCK_PFS(flags);
  
   	seq_printf(m,
   		"proc_sessions             : %u
  "
   		"sys_sessions              : %u
  "
   		"sys_use_dbregs            : %u
  "
   		"ptrace_use_dbregs         : %u
  ",
   		pfm_sessions.pfs_task_sessions,
   		pfm_sessions.pfs_sys_sessions,
   		pfm_sessions.pfs_sys_use_dbregs,
   		pfm_sessions.pfs_ptrace_use_dbregs);
  
    	UNLOCK_PFS(flags);
  
  	spin_lock(&pfm_buffer_fmt_lock);
  
  	list_for_each(pos, &pfm_buffer_fmt_list) {
  		entry = list_entry(pos, pfm_buffer_fmt_t, fmt_list);
  		seq_printf(m, "format                    : %02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x-%02x %s
  ",
  			entry->fmt_uuid[0],
  			entry->fmt_uuid[1],
  			entry->fmt_uuid[2],
  			entry->fmt_uuid[3],
  			entry->fmt_uuid[4],
  			entry->fmt_uuid[5],
  			entry->fmt_uuid[6],
  			entry->fmt_uuid[7],
  			entry->fmt_uuid[8],
  			entry->fmt_uuid[9],
  			entry->fmt_uuid[10],
  			entry->fmt_uuid[11],
  			entry->fmt_uuid[12],
  			entry->fmt_uuid[13],
  			entry->fmt_uuid[14],
  			entry->fmt_uuid[15],
  			entry->fmt_name);
  	}
  	spin_unlock(&pfm_buffer_fmt_lock);
  
  }
  
  static int
  pfm_proc_show(struct seq_file *m, void *v)
  {
  	unsigned long psr;
  	unsigned int i;
  	int cpu;
  
  	if (v == PFM_PROC_SHOW_HEADER) {
  		pfm_proc_show_header(m);
  		return 0;
  	}
  
  	/* show info for CPU (v - 1) */
  
  	cpu = (long)v - 1;
  	seq_printf(m,
  		"CPU%-2d overflow intrs      : %lu
  "
  		"CPU%-2d overflow cycles     : %lu
  "
  		"CPU%-2d overflow min        : %lu
  "
  		"CPU%-2d overflow max        : %lu
  "
  		"CPU%-2d smpl handler calls  : %lu
  "
  		"CPU%-2d smpl handler cycles : %lu
  "
  		"CPU%-2d spurious intrs      : %lu
  "
  		"CPU%-2d replay   intrs      : %lu
  "
  		"CPU%-2d syst_wide           : %d
  "
  		"CPU%-2d dcr_pp              : %d
  "
  		"CPU%-2d exclude idle        : %d
  "
  		"CPU%-2d owner               : %d
  "
  		"CPU%-2d context             : %p
  "
  		"CPU%-2d activations         : %lu
  ",
  		cpu, pfm_stats[cpu].pfm_ovfl_intr_count,
  		cpu, pfm_stats[cpu].pfm_ovfl_intr_cycles,
  		cpu, pfm_stats[cpu].pfm_ovfl_intr_cycles_min,
  		cpu, pfm_stats[cpu].pfm_ovfl_intr_cycles_max,
  		cpu, pfm_stats[cpu].pfm_smpl_handler_calls,
  		cpu, pfm_stats[cpu].pfm_smpl_handler_cycles,
  		cpu, pfm_stats[cpu].pfm_spurious_ovfl_intr_count,
  		cpu, pfm_stats[cpu].pfm_replay_ovfl_intr_count,
  		cpu, pfm_get_cpu_data(pfm_syst_info, cpu) & PFM_CPUINFO_SYST_WIDE ? 1 : 0,
  		cpu, pfm_get_cpu_data(pfm_syst_info, cpu) & PFM_CPUINFO_DCR_PP ? 1 : 0,
  		cpu, pfm_get_cpu_data(pfm_syst_info, cpu) & PFM_CPUINFO_EXCL_IDLE ? 1 : 0,
  		cpu, pfm_get_cpu_data(pmu_owner, cpu) ? pfm_get_cpu_data(pmu_owner, cpu)->pid: -1,
  		cpu, pfm_get_cpu_data(pmu_ctx, cpu),
  		cpu, pfm_get_cpu_data(pmu_activation_number, cpu));
  
  	if (num_online_cpus() == 1 && pfm_sysctl.debug > 0) {
  
  		psr = pfm_get_psr();
  
  		ia64_srlz_d();
  
  		seq_printf(m, 
  			"CPU%-2d psr                 : 0x%lx
  "
  			"CPU%-2d pmc0                : 0x%lx
  ", 
  			cpu, psr,
  			cpu, ia64_get_pmc(0));
  
  		for (i=0; PMC_IS_LAST(i) == 0;  i++) {
  			if (PMC_IS_COUNTING(i) == 0) continue;
     			seq_printf(m, 
  				"CPU%-2d pmc%u                : 0x%lx
  "
     				"CPU%-2d pmd%u                : 0x%lx
  ", 
  				cpu, i, ia64_get_pmc(i),
  				cpu, i, ia64_get_pmd(i));
    		}
  	}
  	return 0;
  }

  const struct seq_operations pfm_seq_ops = {

  	.start =	pfm_proc_start,
   	.next =		pfm_proc_next,
   	.stop =		pfm_proc_stop,
   	.show =		pfm_proc_show
  };
  
  static int
  pfm_proc_open(struct inode *inode, struct file *file)
  {
  	return seq_open(file, &pfm_seq_ops);
  }
  
  
  /*
   * we come here as soon as local_cpu_data->pfm_syst_wide is set. this happens
   * during pfm_enable() hence before pfm_start(). We cannot assume monitoring
   * is active or inactive based on mode. We must rely on the value in
   * local_cpu_data->pfm_syst_info
   */
  void
  pfm_syst_wide_update_task(struct task_struct *task, unsigned long info, int is_ctxswin)
  {
  	struct pt_regs *regs;
  	unsigned long dcr;
  	unsigned long dcr_pp;
  
  	dcr_pp = info & PFM_CPUINFO_DCR_PP ? 1 : 0;
  
  	/*
  	 * pid 0 is guaranteed to be the idle task. There is one such task with pid 0
  	 * on every CPU, so we can rely on the pid to identify the idle task.
  	 */
  	if ((info & PFM_CPUINFO_EXCL_IDLE) == 0 || task->pid) {

  		regs = task_pt_regs(task);

  		ia64_psr(regs)->pp = is_ctxswin ? dcr_pp : 0;
  		return;
  	}
  	/*
  	 * if monitoring has started
  	 */
  	if (dcr_pp) {
  		dcr = ia64_getreg(_IA64_REG_CR_DCR);
  		/*
  		 * context switching in?
  		 */
  		if (is_ctxswin) {
  			/* mask monitoring for the idle task */
  			ia64_setreg(_IA64_REG_CR_DCR, dcr & ~IA64_DCR_PP);
  			pfm_clear_psr_pp();
  			ia64_srlz_i();
  			return;
  		}
  		/*
  		 * context switching out
  		 * restore monitoring for next task
  		 *
  		 * Due to inlining this odd if-then-else construction generates
  		 * better code.
  		 */
  		ia64_setreg(_IA64_REG_CR_DCR, dcr |IA64_DCR_PP);
  		pfm_set_psr_pp();
  		ia64_srlz_i();
  	}
  }
  
  #ifdef CONFIG_SMP
  
  static void
  pfm_force_cleanup(pfm_context_t *ctx, struct pt_regs *regs)
  {
  	struct task_struct *task = ctx->ctx_task;
  
  	ia64_psr(regs)->up = 0;
  	ia64_psr(regs)->sp = 1;
  
  	if (GET_PMU_OWNER() == task) {

  		DPRINT(("cleared ownership for [%d]
  ",
  					task_pid_nr(ctx->ctx_task)));

  		SET_PMU_OWNER(NULL, NULL);
  	}
  
  	/*
  	 * disconnect the task from the context and vice-versa
  	 */
  	PFM_SET_WORK_PENDING(task, 0);
  
  	task->thread.pfm_context  = NULL;
  	task->thread.flags       &= ~IA64_THREAD_PM_VALID;

  	DPRINT(("force cleanup for [%d]
  ",  task_pid_nr(task)));

  }
  
  
  /*
   * in 2.6, interrupts are masked when we come here and the runqueue lock is held
   */
  void
  pfm_save_regs(struct task_struct *task)
  {
  	pfm_context_t *ctx;

  	unsigned long flags;
  	u64 psr;
  
  
  	ctx = PFM_GET_CTX(task);
  	if (ctx == NULL) return;

  
  	/*
   	 * we always come here with interrupts ALREADY disabled by
   	 * the scheduler. So we simply need to protect against concurrent
  	 * access, not CPU concurrency.
  	 */
  	flags = pfm_protect_ctx_ctxsw(ctx);
  
  	if (ctx->ctx_state == PFM_CTX_ZOMBIE) {

  		struct pt_regs *regs = task_pt_regs(task);

  
  		pfm_clear_psr_up();
  
  		pfm_force_cleanup(ctx, regs);
  
  		BUG_ON(ctx->ctx_smpl_hdr);
  
  		pfm_unprotect_ctx_ctxsw(ctx, flags);
  
  		pfm_context_free(ctx);
  		return;
  	}
  
  	/*
  	 * save current PSR: needed because we modify it
  	 */
  	ia64_srlz_d();
  	psr = pfm_get_psr();
  
  	BUG_ON(psr & (IA64_PSR_I));
  
  	/*
  	 * stop monitoring:
  	 * This is the last instruction which may generate an overflow
  	 *
  	 * We do not need to set psr.sp because, it is irrelevant in kernel.
  	 * It will be restored from ipsr when going back to user level
  	 */
  	pfm_clear_psr_up();
  
  	/*
  	 * keep a copy of psr.up (for reload)
  	 */
  	ctx->ctx_saved_psr_up = psr & IA64_PSR_UP;
  
  	/*
  	 * release ownership of this PMU.
  	 * PM interrupts are masked, so nothing
  	 * can happen.
  	 */
  	SET_PMU_OWNER(NULL, NULL);
  
  	/*
  	 * we systematically save the PMD as we have no
  	 * guarantee we will be schedule at that same
  	 * CPU again.
  	 */

  	pfm_save_pmds(ctx->th_pmds, ctx->ctx_used_pmds[0]);

  
  	/*
  	 * save pmc0 ia64_srlz_d() done in pfm_save_pmds()
  	 * we will need it on the restore path to check
  	 * for pending overflow.
  	 */

  	ctx->th_pmcs[0] = ia64_get_pmc(0);

  
  	/*
  	 * unfreeze PMU if had pending overflows
  	 */

  	if (ctx->th_pmcs[0] & ~0x1UL) pfm_unfreeze_pmu();

  
  	/*
  	 * finally, allow context access.
  	 * interrupts will still be masked after this call.
  	 */
  	pfm_unprotect_ctx_ctxsw(ctx, flags);
  }
  
  #else /* !CONFIG_SMP */
  void
  pfm_save_regs(struct task_struct *task)
  {
  	pfm_context_t *ctx;
  	u64 psr;
  
  	ctx = PFM_GET_CTX(task);
  	if (ctx == NULL) return;
  
  	/*
  	 * save current PSR: needed because we modify it
  	 */
  	psr = pfm_get_psr();
  
  	BUG_ON(psr & (IA64_PSR_I));
  
  	/*
  	 * stop monitoring:
  	 * This is the last instruction which may generate an overflow
  	 *
  	 * We do not need to set psr.sp because, it is irrelevant in kernel.
  	 * It will be restored from ipsr when going back to user level
  	 */
  	pfm_clear_psr_up();
  
  	/*
  	 * keep a copy of psr.up (for reload)
  	 */
  	ctx->ctx_saved_psr_up = psr & IA64_PSR_UP;
  }
  
  static void
  pfm_lazy_save_regs (struct task_struct *task)
  {
  	pfm_context_t *ctx;

  	unsigned long flags;
  
  	{ u64 psr  = pfm_get_psr();
  	  BUG_ON(psr & IA64_PSR_UP);
  	}
  
  	ctx = PFM_GET_CTX(task);

  
  	/*
  	 * we need to mask PMU overflow here to
  	 * make sure that we maintain pmc0 until
  	 * we save it. overflow interrupts are
  	 * treated as spurious if there is no
  	 * owner.
  	 *
  	 * XXX: I don't think this is necessary
  	 */
  	PROTECT_CTX(ctx,flags);
  
  	/*
  	 * release ownership of this PMU.
  	 * must be done before we save the registers.
  	 *
  	 * after this call any PMU interrupt is treated
  	 * as spurious.
  	 */
  	SET_PMU_OWNER(NULL, NULL);
  
  	/*
  	 * save all the pmds we use
  	 */

  	pfm_save_pmds(ctx->th_pmds, ctx->ctx_used_pmds[0]);

  
  	/*
  	 * save pmc0 ia64_srlz_d() done in pfm_save_pmds()
  	 * it is needed to check for pended overflow
  	 * on the restore path
  	 */

  	ctx->th_pmcs[0] = ia64_get_pmc(0);

  
  	/*
  	 * unfreeze PMU if had pending overflows
  	 */

  	if (ctx->th_pmcs[0] & ~0x1UL) pfm_unfreeze_pmu();

  
  	/*
  	 * now get can unmask PMU interrupts, they will
  	 * be treated as purely spurious and we will not
  	 * lose any information
  	 */
  	UNPROTECT_CTX(ctx,flags);
  }
  #endif /* CONFIG_SMP */
  
  #ifdef CONFIG_SMP
  /*
   * in 2.6, interrupts are masked when we come here and the runqueue lock is held
   */
  void
  pfm_load_regs (struct task_struct *task)
  {
  	pfm_context_t *ctx;

  	unsigned long pmc_mask = 0UL, pmd_mask = 0UL;
  	unsigned long flags;
  	u64 psr, psr_up;
  	int need_irq_resend;
  
  	ctx = PFM_GET_CTX(task);
  	if (unlikely(ctx == NULL)) return;
  
  	BUG_ON(GET_PMU_OWNER());

  	/*
  	 * possible on unload
  	 */

  	if (unlikely((task->thread.flags & IA64_THREAD_PM_VALID) == 0)) return;

  
  	/*
   	 * we always come here with interrupts ALREADY disabled by
   	 * the scheduler. So we simply need to protect against concurrent
  	 * access, not CPU concurrency.
  	 */
  	flags = pfm_protect_ctx_ctxsw(ctx);
  	psr   = pfm_get_psr();
  
  	need_irq_resend = pmu_conf->flags & PFM_PMU_IRQ_RESEND;
  
  	BUG_ON(psr & (IA64_PSR_UP|IA64_PSR_PP));
  	BUG_ON(psr & IA64_PSR_I);
  
  	if (unlikely(ctx->ctx_state == PFM_CTX_ZOMBIE)) {

  		struct pt_regs *regs = task_pt_regs(task);

  
  		BUG_ON(ctx->ctx_smpl_hdr);
  
  		pfm_force_cleanup(ctx, regs);
  
  		pfm_unprotect_ctx_ctxsw(ctx, flags);
  
  		/*
  		 * this one (kmalloc'ed) is fine with interrupts disabled
  		 */
  		pfm_context_free(ctx);
  
  		return;
  	}
  
  	/*
  	 * we restore ALL the debug registers to avoid picking up
  	 * stale state.
  	 */
  	if (ctx->ctx_fl_using_dbreg) {
  		pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
  		pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
  	}
  	/*
  	 * retrieve saved psr.up
  	 */
  	psr_up = ctx->ctx_saved_psr_up;
  
  	/*
  	 * if we were the last user of the PMU on that CPU,
  	 * then nothing to do except restore psr
  	 */
  	if (GET_LAST_CPU(ctx) == smp_processor_id() && ctx->ctx_last_activation == GET_ACTIVATION()) {
  
  		/*
  		 * retrieve partial reload masks (due to user modifications)
  		 */
  		pmc_mask = ctx->ctx_reload_pmcs[0];
  		pmd_mask = ctx->ctx_reload_pmds[0];
  
  	} else {
  		/*
  	 	 * To avoid leaking information to the user level when psr.sp=0,
  	 	 * we must reload ALL implemented pmds (even the ones we don't use).
  	 	 * In the kernel we only allow PFM_READ_PMDS on registers which
  	 	 * we initialized or requested (sampling) so there is no risk there.
  	 	 */
  		pmd_mask = pfm_sysctl.fastctxsw ?  ctx->ctx_used_pmds[0] : ctx->ctx_all_pmds[0];
  
  		/*
  	 	 * ALL accessible PMCs are systematically reloaded, unused registers
  	 	 * get their default (from pfm_reset_pmu_state()) values to avoid picking
  	 	 * up stale configuration.
  	 	 *
  	 	 * PMC0 is never in the mask. It is always restored separately.
  	 	 */
  		pmc_mask = ctx->ctx_all_pmcs[0];
  	}
  	/*
  	 * when context is MASKED, we will restore PMC with plm=0
  	 * and PMD with stale information, but that's ok, nothing
  	 * will be captured.
  	 *
  	 * XXX: optimize here
  	 */

  	if (pmd_mask) pfm_restore_pmds(ctx->th_pmds, pmd_mask);
  	if (pmc_mask) pfm_restore_pmcs(ctx->th_pmcs, pmc_mask);

  
  	/*
  	 * check for pending overflow at the time the state
  	 * was saved.
  	 */

  	if (unlikely(PMC0_HAS_OVFL(ctx->th_pmcs[0]))) {

  		/*
  		 * reload pmc0 with the overflow information
  		 * On McKinley PMU, this will trigger a PMU interrupt
  		 */

  		ia64_set_pmc(0, ctx->th_pmcs[0]);

  		ia64_srlz_d();

  		ctx->th_pmcs[0] = 0UL;

  
  		/*
  		 * will replay the PMU interrupt
  		 */

  		if (need_irq_resend) ia64_resend_irq(IA64_PERFMON_VECTOR);

  
  		pfm_stats[smp_processor_id()].pfm_replay_ovfl_intr_count++;
  	}
  
  	/*
  	 * we just did a reload, so we reset the partial reload fields
  	 */
  	ctx->ctx_reload_pmcs[0] = 0UL;
  	ctx->ctx_reload_pmds[0] = 0UL;
  
  	SET_LAST_CPU(ctx, smp_processor_id());
  
  	/*
  	 * dump activation value for this PMU
  	 */
  	INC_ACTIVATION();
  	/*
  	 * record current activation for this context
  	 */
  	SET_ACTIVATION(ctx);
  
  	/*
  	 * establish new ownership. 
  	 */
  	SET_PMU_OWNER(task, ctx);
  
  	/*
  	 * restore the psr.up bit. measurement
  	 * is active again.
  	 * no PMU interrupt can happen at this point
  	 * because we still have interrupts disabled.
  	 */
  	if (likely(psr_up)) pfm_set_psr_up();
  
  	/*
  	 * allow concurrent access to context
  	 */
  	pfm_unprotect_ctx_ctxsw(ctx, flags);
  }
  #else /*  !CONFIG_SMP */
  /*
   * reload PMU state for UP kernels
   * in 2.5 we come here with interrupts disabled
   */
  void
  pfm_load_regs (struct task_struct *task)
  {

  	pfm_context_t *ctx;
  	struct task_struct *owner;
  	unsigned long pmd_mask, pmc_mask;
  	u64 psr, psr_up;
  	int need_irq_resend;
  
  	owner = GET_PMU_OWNER();
  	ctx   = PFM_GET_CTX(task);

  	psr   = pfm_get_psr();
  
  	BUG_ON(psr & (IA64_PSR_UP|IA64_PSR_PP));
  	BUG_ON(psr & IA64_PSR_I);
  
  	/*
  	 * we restore ALL the debug registers to avoid picking up
  	 * stale state.
  	 *
  	 * This must be done even when the task is still the owner
  	 * as the registers may have been modified via ptrace()
  	 * (not perfmon) by the previous task.
  	 */
  	if (ctx->ctx_fl_using_dbreg) {
  		pfm_restore_ibrs(ctx->ctx_ibrs, pmu_conf->num_ibrs);
  		pfm_restore_dbrs(ctx->ctx_dbrs, pmu_conf->num_dbrs);
  	}
  
  	/*
  	 * retrieved saved psr.up
  	 */
  	psr_up = ctx->ctx_saved_psr_up;
  	need_irq_resend = pmu_conf->flags & PFM_PMU_IRQ_RESEND;
  
  	/*
  	 * short path, our state is still there, just
  	 * need to restore psr and we go
  	 *
  	 * we do not touch either PMC nor PMD. the psr is not touched
  	 * by the overflow_handler. So we are safe w.r.t. to interrupt
  	 * concurrency even without interrupt masking.
  	 */
  	if (likely(owner == task)) {
  		if (likely(psr_up)) pfm_set_psr_up();
  		return;
  	}
  
  	/*
  	 * someone else is still using the PMU, first push it out and
  	 * then we'll be able to install our stuff !
  	 *
  	 * Upon return, there will be no owner for the current PMU
  	 */
  	if (owner) pfm_lazy_save_regs(owner);
  
  	/*
  	 * To avoid leaking information to the user level when psr.sp=0,
  	 * we must reload ALL implemented pmds (even the ones we don't use).
  	 * In the kernel we only allow PFM_READ_PMDS on registers which
  	 * we initialized or requested (sampling) so there is no risk there.
  	 */
  	pmd_mask = pfm_sysctl.fastctxsw ?  ctx->ctx_used_pmds[0] : ctx->ctx_all_pmds[0];
  
  	/*
  	 * ALL accessible PMCs are systematically reloaded, unused registers
  	 * get their default (from pfm_reset_pmu_state()) values to avoid picking
  	 * up stale configuration.
  	 *
  	 * PMC0 is never in the mask. It is always restored separately
  	 */
  	pmc_mask = ctx->ctx_all_pmcs[0];

  	pfm_restore_pmds(ctx->th_pmds, pmd_mask);
  	pfm_restore_pmcs(ctx->th_pmcs, pmc_mask);

  
  	/*
  	 * check for pending overflow at the time the state
  	 * was saved.
  	 */

  	if (unlikely(PMC0_HAS_OVFL(ctx->th_pmcs[0]))) {

  		/*
  		 * reload pmc0 with the overflow information
  		 * On McKinley PMU, this will trigger a PMU interrupt
  		 */

  		ia64_set_pmc(0, ctx->th_pmcs[0]);

  		ia64_srlz_d();

  		ctx->th_pmcs[0] = 0UL;

  
  		/*
  		 * will replay the PMU interrupt
  		 */

  		if (need_irq_resend) ia64_resend_irq(IA64_PERFMON_VECTOR);

  
  		pfm_stats[smp_processor_id()].pfm_replay_ovfl_intr_count++;
  	}
  
  	/*
  	 * establish new ownership. 
  	 */
  	SET_PMU_OWNER(task, ctx);
  
  	/*
  	 * restore the psr.up bit. measurement
  	 * is active again.
  	 * no PMU interrupt can happen at this point
  	 * because we still have interrupts disabled.
  	 */
  	if (likely(psr_up)) pfm_set_psr_up();
  }
  #endif /* CONFIG_SMP */
  
  /*
   * this function assumes monitoring is stopped
   */
  static void
  pfm_flush_pmds(struct task_struct *task, pfm_context_t *ctx)
  {
  	u64 pmc0;
  	unsigned long mask2, val, pmd_val, ovfl_val;
  	int i, can_access_pmu = 0;
  	int is_self;
  
  	/*
  	 * is the caller the task being monitored (or which initiated the
  	 * session for system wide measurements)
  	 */
  	is_self = ctx->ctx_task == task ? 1 : 0;
  
  	/*
  	 * can access PMU is task is the owner of the PMU state on the current CPU
  	 * or if we are running on the CPU bound to the context in system-wide mode
  	 * (that is not necessarily the task the context is attached to in this mode).
  	 * In system-wide we always have can_access_pmu true because a task running on an
  	 * invalid processor is flagged earlier in the call stack (see pfm_stop).
  	 */
  	can_access_pmu = (GET_PMU_OWNER() == task) || (ctx->ctx_fl_system && ctx->ctx_cpu == smp_processor_id());
  	if (can_access_pmu) {
  		/*
  		 * Mark the PMU as not owned
  		 * This will cause the interrupt handler to do nothing in case an overflow
  		 * interrupt was in-flight
  		 * This also guarantees that pmc0 will contain the final state
  		 * It virtually gives us full control on overflow processing from that point
  		 * on.
  		 */
  		SET_PMU_OWNER(NULL, NULL);
  		DPRINT(("releasing ownership
  "));
  
  		/*
  		 * read current overflow status:
  		 *
  		 * we are guaranteed to read the final stable state
  		 */
  		ia64_srlz_d();
  		pmc0 = ia64_get_pmc(0); /* slow */
  
  		/*
  		 * reset freeze bit, overflow status information destroyed
  		 */
  		pfm_unfreeze_pmu();
  	} else {

  		pmc0 = ctx->th_pmcs[0];

  		/*
  		 * clear whatever overflow status bits there were
  		 */

  		ctx->th_pmcs[0] = 0;

  	}
  	ovfl_val = pmu_conf->ovfl_val;
  	/*
  	 * we save all the used pmds
  	 * we take care of overflows for counting PMDs
  	 *
  	 * XXX: sampling situation is not taken into account here
  	 */
  	mask2 = ctx->ctx_used_pmds[0];
  
  	DPRINT(("is_self=%d ovfl_val=0x%lx mask2=0x%lx
  ", is_self, ovfl_val, mask2));
  
  	for (i = 0; mask2; i++, mask2>>=1) {
  
  		/* skip non used pmds */
  		if ((mask2 & 0x1) == 0) continue;
  
  		/*
  		 * can access PMU always true in system wide mode
  		 */

  		val = pmd_val = can_access_pmu ? ia64_get_pmd(i) : ctx->th_pmds[i];

  
  		if (PMD_IS_COUNTING(i)) {
  			DPRINT(("[%d] pmd[%d] ctx_pmd=0x%lx hw_pmd=0x%lx
  ",

  				task_pid_nr(task),

  				i,
  				ctx->ctx_pmds[i].val,
  				val & ovfl_val));
  
  			/*
  			 * we rebuild the full 64 bit value of the counter
  			 */
  			val = ctx->ctx_pmds[i].val + (val & ovfl_val);
  
  			/*
  			 * now everything is in ctx_pmds[] and we need
  			 * to clear the saved context from save_regs() such that
  			 * pfm_read_pmds() gets the correct value
  			 */
  			pmd_val = 0UL;
  
  			/*
  			 * take care of overflow inline
  			 */
  			if (pmc0 & (1UL << i)) {
  				val += 1 + ovfl_val;

  				DPRINT(("[%d] pmd[%d] overflowed
  ", task_pid_nr(task), i));

  			}
  		}

  		DPRINT(("[%d] ctx_pmd[%d]=0x%lx  pmd_val=0x%lx
  ", task_pid_nr(task), i, val, pmd_val));

  		if (is_self) ctx->th_pmds[i] = pmd_val;

  
  		ctx->ctx_pmds[i].val = val;
  	}
  }
  
  static struct irqaction perfmon_irqaction = {
  	.handler = pfm_interrupt_handler,

  	.flags   = IRQF_DISABLED,

  	.name    = "perfmon"
  };

  static void
  pfm_alt_save_pmu_state(void *data)
  {
  	struct pt_regs *regs;

  	regs = task_pt_regs(current);

  
  	DPRINT(("called
  "));
  
  	/*
  	 * should not be necessary but
  	 * let's take not risk
  	 */
  	pfm_clear_psr_up();
  	pfm_clear_psr_pp();
  	ia64_psr(regs)->pp = 0;
  
  	/*
  	 * This call is required
  	 * May cause a spurious interrupt on some processors
  	 */
  	pfm_freeze_pmu();
  
  	ia64_srlz_d();
  }
  
  void
  pfm_alt_restore_pmu_state(void *data)
  {
  	struct pt_regs *regs;

  	regs = task_pt_regs(current);

  
  	DPRINT(("called
  "));
  
  	/*
  	 * put PMU back in state expected
  	 * by perfmon
  	 */
  	pfm_clear_psr_up();
  	pfm_clear_psr_pp();
  	ia64_psr(regs)->pp = 0;
  
  	/*
  	 * perfmon runs with PMU unfrozen at all times
  	 */
  	pfm_unfreeze_pmu();
  
  	ia64_srlz_d();
  }
  
  int
  pfm_install_alt_pmu_interrupt(pfm_intr_handler_desc_t *hdl)
  {
  	int ret, i;
  	int reserve_cpu;
  
  	/* some sanity checks */
  	if (hdl == NULL || hdl->handler == NULL) return -EINVAL;
  
  	/* do the easy test first */
  	if (pfm_alt_intr_handler) return -EBUSY;
  
  	/* one at a time in the install or remove, just fail the others */
  	if (!spin_trylock(&pfm_alt_install_check)) {
  		return -EBUSY;
  	}
  
  	/* reserve our session */
  	for_each_online_cpu(reserve_cpu) {
  		ret = pfm_reserve_session(NULL, 1, reserve_cpu);
  		if (ret) goto cleanup_reserve;
  	}
  
  	/* save the current system wide pmu states */

  	ret = on_each_cpu(pfm_alt_save_pmu_state, NULL, 1);

  	if (ret) {
  		DPRINT(("on_each_cpu() failed: %d
  ", ret));
  		goto cleanup_reserve;
  	}
  
  	/* officially change to the alternate interrupt handler */
  	pfm_alt_intr_handler = hdl;
  
  	spin_unlock(&pfm_alt_install_check);
  
  	return 0;
  
  cleanup_reserve:
  	for_each_online_cpu(i) {
  		/* don't unreserve more than we reserved */
  		if (i >= reserve_cpu) break;
  
  		pfm_unreserve_session(NULL, 1, i);
  	}
  
  	spin_unlock(&pfm_alt_install_check);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(pfm_install_alt_pmu_interrupt);
  
  int
  pfm_remove_alt_pmu_interrupt(pfm_intr_handler_desc_t *hdl)
  {
  	int i;
  	int ret;
  
  	if (hdl == NULL) return -EINVAL;
  
  	/* cannot remove someone else's handler! */
  	if (pfm_alt_intr_handler != hdl) return -EINVAL;
  
  	/* one at a time in the install or remove, just fail the others */
  	if (!spin_trylock(&pfm_alt_install_check)) {
  		return -EBUSY;
  	}
  
  	pfm_alt_intr_handler = NULL;

  	ret = on_each_cpu(pfm_alt_restore_pmu_state, NULL, 1);

  	if (ret) {
  		DPRINT(("on_each_cpu() failed: %d
  ", ret));
  	}
  
  	for_each_online_cpu(i) {
  		pfm_unreserve_session(NULL, 1, i);
  	}
  
  	spin_unlock(&pfm_alt_install_check);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(pfm_remove_alt_pmu_interrupt);

  /*
   * perfmon initialization routine, called from the initcall() table
   */
  static int init_pfm_fs(void);
  
  static int __init
  pfm_probe_pmu(void)
  {
  	pmu_config_t **p;
  	int family;
  
  	family = local_cpu_data->family;
  	p      = pmu_confs;
  
  	while(*p) {
  		if ((*p)->probe) {
  			if ((*p)->probe() == 0) goto found;
  		} else if ((*p)->pmu_family == family || (*p)->pmu_family == 0xff) {
  			goto found;
  		}
  		p++;
  	}
  	return -1;
  found:
  	pmu_conf = *p;
  	return 0;
  }

  static const struct file_operations pfm_proc_fops = {

  	.open		= pfm_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= seq_release,
  };
  
  int __init
  pfm_init(void)
  {
  	unsigned int n, n_counters, i;
  
  	printk("perfmon: version %u.%u IRQ %u
  ",
  		PFM_VERSION_MAJ,
  		PFM_VERSION_MIN,
  		IA64_PERFMON_VECTOR);
  
  	if (pfm_probe_pmu()) {
  		printk(KERN_INFO "perfmon: disabled, there is no support for processor family %d
  ", 
  				local_cpu_data->family);
  		return -ENODEV;
  	}
  
  	/*
  	 * compute the number of implemented PMD/PMC from the
  	 * description tables
  	 */
  	n = 0;
  	for (i=0; PMC_IS_LAST(i) == 0;  i++) {
  		if (PMC_IS_IMPL(i) == 0) continue;
  		pmu_conf->impl_pmcs[i>>6] |= 1UL << (i&63);
  		n++;
  	}
  	pmu_conf->num_pmcs = n;
  
  	n = 0; n_counters = 0;
  	for (i=0; PMD_IS_LAST(i) == 0;  i++) {
  		if (PMD_IS_IMPL(i) == 0) continue;
  		pmu_conf->impl_pmds[i>>6] |= 1UL << (i&63);
  		n++;
  		if (PMD_IS_COUNTING(i)) n_counters++;
  	}
  	pmu_conf->num_pmds      = n;
  	pmu_conf->num_counters  = n_counters;
  
  	/*
  	 * sanity checks on the number of debug registers
  	 */
  	if (pmu_conf->use_rr_dbregs) {
  		if (pmu_conf->num_ibrs > IA64_NUM_DBG_REGS) {
  			printk(KERN_INFO "perfmon: unsupported number of code debug registers (%u)
  ", pmu_conf->num_ibrs);
  			pmu_conf = NULL;
  			return -1;
  		}
  		if (pmu_conf->num_dbrs > IA64_NUM_DBG_REGS) {
  			printk(KERN_INFO "perfmon: unsupported number of data debug registers (%u)
  ", pmu_conf->num_ibrs);
  			pmu_conf = NULL;
  			return -1;
  		}
  	}
  
  	printk("perfmon: %s PMU detected, %u PMCs, %u PMDs, %u counters (%lu bits)
  ",
  	       pmu_conf->pmu_name,
  	       pmu_conf->num_pmcs,
  	       pmu_conf->num_pmds,
  	       pmu_conf->num_counters,
  	       ffz(pmu_conf->ovfl_val));
  
  	/* sanity check */

  	if (pmu_conf->num_pmds >= PFM_NUM_PMD_REGS || pmu_conf->num_pmcs >= PFM_NUM_PMC_REGS) {

  		printk(KERN_ERR "perfmon: not enough pmc/pmd, perfmon disabled
  ");
  		pmu_conf = NULL;
  		return -1;
  	}
  
  	/*
  	 * create /proc/perfmon (mostly for debugging purposes)
  	 */

  	perfmon_dir = proc_create("perfmon", S_IRUGO, NULL, &pfm_proc_fops);

  	if (perfmon_dir == NULL) {
  		printk(KERN_ERR "perfmon: cannot create /proc entry, perfmon disabled
  ");
  		pmu_conf = NULL;
  		return -1;
  	}

  
  	/*
  	 * create /proc/sys/kernel/perfmon (for debugging purposes)
  	 */

  	pfm_sysctl_header = register_sysctl_table(pfm_sysctl_root);

  
  	/*
  	 * initialize all our spinlocks
  	 */
  	spin_lock_init(&pfm_sessions.pfs_lock);
  	spin_lock_init(&pfm_buffer_fmt_lock);
  
  	init_pfm_fs();
  
  	for(i=0; i < NR_CPUS; i++) pfm_stats[i].pfm_ovfl_intr_cycles_min = ~0UL;
  
  	return 0;
  }
  
  __initcall(pfm_init);
  
  /*
   * this function is called before pfm_init()
   */
  void
  pfm_init_percpu (void)
  {

  	static int first_time=1;

  	/*
  	 * make sure no measurement is active
  	 * (may inherit programmed PMCs from EFI).
  	 */
  	pfm_clear_psr_pp();
  	pfm_clear_psr_up();
  
  	/*
  	 * we run with the PMU not frozen at all times
  	 */
  	pfm_unfreeze_pmu();

  	if (first_time) {

  		register_percpu_irq(IA64_PERFMON_VECTOR, &perfmon_irqaction);

  		first_time=0;
  	}

  
  	ia64_setreg(_IA64_REG_CR_PMV, IA64_PERFMON_VECTOR);
  	ia64_srlz_d();
  }
  
  /*
   * used for debug purposes only
   */
  void
  dump_pmu_state(const char *from)
  {
  	struct task_struct *task;

  	struct pt_regs *regs;
  	pfm_context_t *ctx;
  	unsigned long psr, dcr, info, flags;
  	int i, this_cpu;
  
  	local_irq_save(flags);
  
  	this_cpu = smp_processor_id();

  	regs     = task_pt_regs(current);

  	info     = PFM_CPUINFO_GET();
  	dcr      = ia64_getreg(_IA64_REG_CR_DCR);
  
  	if (info == 0 && ia64_psr(regs)->pp == 0 && (dcr & IA64_DCR_PP) == 0) {
  		local_irq_restore(flags);
  		return;
  	}
  
  	printk("CPU%d from %s() current [%d] iip=0x%lx %s
  ", 
  		this_cpu, 
  		from, 

  		task_pid_nr(current),

  		regs->cr_iip,
  		current->comm);
  
  	task = GET_PMU_OWNER();
  	ctx  = GET_PMU_CTX();

  	printk("->CPU%d owner [%d] ctx=%p
  ", this_cpu, task ? task_pid_nr(task) : -1, ctx);

  
  	psr = pfm_get_psr();
  
  	printk("->CPU%d pmc0=0x%lx psr.pp=%d psr.up=%d dcr.pp=%d syst_info=0x%lx user_psr.up=%d user_psr.pp=%d
  ", 
  		this_cpu,
  		ia64_get_pmc(0),
  		psr & IA64_PSR_PP ? 1 : 0,
  		psr & IA64_PSR_UP ? 1 : 0,
  		dcr & IA64_DCR_PP ? 1 : 0,
  		info,
  		ia64_psr(regs)->up,
  		ia64_psr(regs)->pp);
  
  	ia64_psr(regs)->up = 0;
  	ia64_psr(regs)->pp = 0;

  	for (i=1; PMC_IS_LAST(i) == 0; i++) {
  		if (PMC_IS_IMPL(i) == 0) continue;

  		printk("->CPU%d pmc[%d]=0x%lx thread_pmc[%d]=0x%lx
  ", this_cpu, i, ia64_get_pmc(i), i, ctx->th_pmcs[i]);

  	}
  
  	for (i=1; PMD_IS_LAST(i) == 0; i++) {
  		if (PMD_IS_IMPL(i) == 0) continue;

  		printk("->CPU%d pmd[%d]=0x%lx thread_pmd[%d]=0x%lx
  ", this_cpu, i, ia64_get_pmd(i), i, ctx->th_pmds[i]);

  	}
  
  	if (ctx) {
  		printk("->CPU%d ctx_state=%d vaddr=%p addr=%p fd=%d ctx_task=[%d] saved_psr_up=0x%lx
  ",
  				this_cpu,
  				ctx->ctx_state,
  				ctx->ctx_smpl_vaddr,
  				ctx->ctx_smpl_hdr,
  				ctx->ctx_msgq_head,
  				ctx->ctx_msgq_tail,
  				ctx->ctx_saved_psr_up);
  	}
  	local_irq_restore(flags);
  }
  
  /*
   * called from process.c:copy_thread(). task is new child.
   */
  void
  pfm_inherit(struct task_struct *task, struct pt_regs *regs)
  {
  	struct thread_struct *thread;

  	DPRINT(("perfmon: pfm_inherit clearing state for [%d]
  ", task_pid_nr(task)));

  
  	thread = &task->thread;
  
  	/*
  	 * cut links inherited from parent (current)
  	 */
  	thread->pfm_context = NULL;
  
  	PFM_SET_WORK_PENDING(task, 0);
  
  	/*
  	 * the psr bits are already set properly in copy_threads()
  	 */
  }
  #else  /* !CONFIG_PERFMON */
  asmlinkage long
  sys_perfmonctl (int fd, int cmd, void *arg, int count)
  {
  	return -ENOSYS;
  }
  #endif /* CONFIG_PERFMON */