/**
   * @file common.c
   *
   * @remark Copyright 2004 Oprofile Authors

   * @remark Copyright 2010 ARM Ltd.

   * @remark Read the file COPYING
   *
   * @author Zwane Mwaikambo

   * @author Will Deacon [move to perf]

   */

  #include <linux/cpumask.h>

  #include <linux/init.h>

  #include <linux/mutex.h>

  #include <linux/oprofile.h>

  #include <linux/perf_event.h>

  #include <linux/platform_device.h>

  #include <linux/slab.h>

  #include <asm/stacktrace.h>
  #include <linux/uaccess.h>
  
  #include <asm/perf_event.h>
  #include <asm/ptrace.h>

  #ifdef CONFIG_HW_PERF_EVENTS

  char *op_name_from_perf_id(void)

  {

  	enum arm_perf_pmu_ids id = armpmu_get_pmu_id();

  	switch (id) {
  	case ARM_PERF_PMU_ID_XSCALE1:
  		return "arm/xscale1";
  	case ARM_PERF_PMU_ID_XSCALE2:
  		return "arm/xscale2";
  	case ARM_PERF_PMU_ID_V6:
  		return "arm/armv6";
  	case ARM_PERF_PMU_ID_V6MP:
  		return "arm/mpcore";
  	case ARM_PERF_PMU_ID_CA8:
  		return "arm/armv7";
  	case ARM_PERF_PMU_ID_CA9:
  		return "arm/armv7-ca9";
  	default:
  		return NULL;
  	}
  }

  #endif

  static int report_trace(struct stackframe *frame, void *d)

  {

  	unsigned int *depth = d;

  	if (*depth) {
  		oprofile_add_trace(frame->pc);
  		(*depth)--;
  	}

  	return *depth == 0;
  }

  /*
   * The registers we're interested in are at the end of the variable
   * length saved register structure. The fp points at the end of this
   * structure so the address of this struct is:
   * (struct frame_tail *)(xxx->fp)-1
   */
  struct frame_tail {
  	struct frame_tail *fp;
  	unsigned long sp;
  	unsigned long lr;
  } __attribute__((packed));

  static struct frame_tail* user_backtrace(struct frame_tail *tail)
  {
  	struct frame_tail buftail[2];

  	/* Also check accessibility of one struct frame_tail beyond */
  	if (!access_ok(VERIFY_READ, tail, sizeof(buftail)))
  		return NULL;
  	if (__copy_from_user_inatomic(buftail, tail, sizeof(buftail)))
  		return NULL;

  	oprofile_add_trace(buftail[0].lr);

  	/* frame pointers should strictly progress back up the stack
  	 * (towards higher addresses) */

  	if (tail + 1 >= buftail[0].fp)

  		return NULL;
  
  	return buftail[0].fp-1;
  }
  
  static void arm_backtrace(struct pt_regs * const regs, unsigned int depth)
  {
  	struct frame_tail *tail = ((struct frame_tail *) regs->ARM_fp) - 1;
  
  	if (!user_mode(regs)) {
  		struct stackframe frame;
  		frame.fp = regs->ARM_fp;
  		frame.sp = regs->ARM_sp;
  		frame.lr = regs->ARM_lr;
  		frame.pc = regs->ARM_pc;
  		walk_stackframe(&frame, report_trace, &depth);
  		return;
  	}
  
  	while (depth-- && tail && !((unsigned long) tail & 3))
  		tail = user_backtrace(tail);
  }

  int __init oprofile_arch_init(struct oprofile_operations *ops)
  {

  	/* provide backtrace support also in timer mode: */

  	ops->backtrace		= arm_backtrace;
  
  	return oprofile_perf_init(ops);
  }

  void oprofile_arch_exit(void)

  {
  	oprofile_perf_exit();
  }