/*
   *  linux/kernel/profile.c
   *  Simple profiling. Manages a direct-mapped profile hit count buffer,
   *  with configurable resolution, support for restricting the cpus on
   *  which profiling is done, and switching between cpu time and
   *  schedule() calls via kernel command line parameters passed at boot.
   *
   *  Scheduler profiling support, Arjan van de Ven and Ingo Molnar,
   *	Red Hat, July 2004
   *  Consolidation of architecture support code for profiling,

   *	Nadia Yvette Chambers, Oracle, July 2004

   *  Amortized hit count accounting via per-cpu open-addressed hashtables

   *	to resolve timer interrupt livelocks, Nadia Yvette Chambers,
   *	Oracle, 2004

   */

  #include <linux/export.h>

  #include <linux/profile.h>
  #include <linux/bootmem.h>
  #include <linux/notifier.h>
  #include <linux/mm.h>
  #include <linux/cpumask.h>
  #include <linux/cpu.h>

  #include <linux/highmem.h>

  #include <linux/mutex.h>

  #include <linux/slab.h>
  #include <linux/vmalloc.h>

  #include <linux/sched/stat.h>

  #include <asm/sections.h>

  #include <asm/irq_regs.h>

  #include <asm/ptrace.h>

  
  struct profile_hit {
  	u32 pc, hits;
  };
  #define PROFILE_GRPSHIFT	3
  #define PROFILE_GRPSZ		(1 << PROFILE_GRPSHIFT)
  #define NR_PROFILE_HIT		(PAGE_SIZE/sizeof(struct profile_hit))
  #define NR_PROFILE_GRP		(NR_PROFILE_HIT/PROFILE_GRPSZ)

  static atomic_t *prof_buffer;
  static unsigned long prof_len, prof_shift;

  int prof_on __read_mostly;

  EXPORT_SYMBOL_GPL(prof_on);

  static cpumask_var_t prof_cpu_mask;

  #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)

  static DEFINE_PER_CPU(struct profile_hit *[2], cpu_profile_hits);
  static DEFINE_PER_CPU(int, cpu_profile_flip);

  static DEFINE_MUTEX(profile_flip_mutex);

  #endif /* CONFIG_SMP */

  int profile_setup(char *str)

  {

  	static const char schedstr[] = "schedule";
  	static const char sleepstr[] = "sleep";
  	static const char kvmstr[] = "kvm";

  	int par;

  	if (!strncmp(str, sleepstr, strlen(sleepstr))) {

  #ifdef CONFIG_SCHEDSTATS

  		force_schedstat_enabled();

  		prof_on = SLEEP_PROFILING;
  		if (str[strlen(sleepstr)] == ',')
  			str += strlen(sleepstr) + 1;
  		if (get_option(&str, &par))
  			prof_shift = par;

  		pr_info("kernel sleep profiling enabled (shift: %ld)
  ",

  			prof_shift);

  #else

  		pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS
  ");

  #endif /* CONFIG_SCHEDSTATS */

  	} else if (!strncmp(str, schedstr, strlen(schedstr))) {

  		prof_on = SCHED_PROFILING;

  		if (str[strlen(schedstr)] == ',')
  			str += strlen(schedstr) + 1;
  		if (get_option(&str, &par))
  			prof_shift = par;

  		pr_info("kernel schedule profiling enabled (shift: %ld)
  ",

  			prof_shift);

  	} else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
  		prof_on = KVM_PROFILING;
  		if (str[strlen(kvmstr)] == ',')
  			str += strlen(kvmstr) + 1;
  		if (get_option(&str, &par))
  			prof_shift = par;

  		pr_info("kernel KVM profiling enabled (shift: %ld)
  ",

  			prof_shift);

  	} else if (get_option(&str, &par)) {

  		prof_shift = par;
  		prof_on = CPU_PROFILING;

  		pr_info("kernel profiling enabled (shift: %ld)
  ",

  			prof_shift);
  	}
  	return 1;
  }
  __setup("profile=", profile_setup);

  int __ref profile_init(void)

  {

  	int buffer_bytes;

  	if (!prof_on)

  		return 0;

  	/* only text is profiled */
  	prof_len = (_etext - _stext) >> prof_shift;

  	buffer_bytes = prof_len*sizeof(atomic_t);

  	if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
  		return -ENOMEM;

  	cpumask_copy(prof_cpu_mask, cpu_possible_mask);

  	prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);

  	if (prof_buffer)
  		return 0;

  	prof_buffer = alloc_pages_exact(buffer_bytes,
  					GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);

  	if (prof_buffer)
  		return 0;

  	prof_buffer = vzalloc(buffer_bytes);
  	if (prof_buffer)

  		return 0;

  	free_cpumask_var(prof_cpu_mask);

  	return -ENOMEM;

  }
  
  /* Profile event notifications */

  static BLOCKING_NOTIFIER_HEAD(task_exit_notifier);
  static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
  static BLOCKING_NOTIFIER_HEAD(munmap_notifier);

  
  void profile_task_exit(struct task_struct *task)

  {

  	blocking_notifier_call_chain(&task_exit_notifier, 0, task);

  }

  
  int profile_handoff_task(struct task_struct *task)

  {
  	int ret;

  	ret = atomic_notifier_call_chain(&task_free_notifier, 0, task);

  	return (ret == NOTIFY_OK) ? 1 : 0;
  }
  
  void profile_munmap(unsigned long addr)
  {

  	blocking_notifier_call_chain(&munmap_notifier, 0, (void *)addr);

  }

  int task_handoff_register(struct notifier_block *n)

  {

  	return atomic_notifier_chain_register(&task_free_notifier, n);

  }

  EXPORT_SYMBOL_GPL(task_handoff_register);

  int task_handoff_unregister(struct notifier_block *n)

  {

  	return atomic_notifier_chain_unregister(&task_free_notifier, n);

  }

  EXPORT_SYMBOL_GPL(task_handoff_unregister);

  int profile_event_register(enum profile_type type, struct notifier_block *n)

  {
  	int err = -EINVAL;

  	switch (type) {

  	case PROFILE_TASK_EXIT:
  		err = blocking_notifier_chain_register(
  				&task_exit_notifier, n);
  		break;
  	case PROFILE_MUNMAP:
  		err = blocking_notifier_chain_register(
  				&munmap_notifier, n);
  		break;

  	}

  	return err;
  }

  EXPORT_SYMBOL_GPL(profile_event_register);

  int profile_event_unregister(enum profile_type type, struct notifier_block *n)

  {
  	int err = -EINVAL;

  	switch (type) {

  	case PROFILE_TASK_EXIT:
  		err = blocking_notifier_chain_unregister(
  				&task_exit_notifier, n);
  		break;
  	case PROFILE_MUNMAP:
  		err = blocking_notifier_chain_unregister(
  				&munmap_notifier, n);
  		break;

  	}

  	return err;
  }

  EXPORT_SYMBOL_GPL(profile_event_unregister);

  #if defined(CONFIG_SMP) && defined(CONFIG_PROC_FS)

  /*
   * Each cpu has a pair of open-addressed hashtables for pending
   * profile hits. read_profile() IPI's all cpus to request them
   * to flip buffers and flushes their contents to prof_buffer itself.
   * Flip requests are serialized by the profile_flip_mutex. The sole
   * use of having a second hashtable is for avoiding cacheline
   * contention that would otherwise happen during flushes of pending
   * profile hits required for the accuracy of reported profile hits
   * and so resurrect the interrupt livelock issue.
   *
   * The open-addressed hashtables are indexed by profile buffer slot
   * and hold the number of pending hits to that profile buffer slot on
   * a cpu in an entry. When the hashtable overflows, all pending hits
   * are accounted to their corresponding profile buffer slots with
   * atomic_add() and the hashtable emptied. As numerous pending hits
   * may be accounted to a profile buffer slot in a hashtable entry,
   * this amortizes a number of atomic profile buffer increments likely
   * to be far larger than the number of entries in the hashtable,
   * particularly given that the number of distinct profile buffer
   * positions to which hits are accounted during short intervals (e.g.
   * several seconds) is usually very small. Exclusion from buffer
   * flipping is provided by interrupt disablement (note that for

   * SCHED_PROFILING or SLEEP_PROFILING profile_hit() may be called from
   * process context).

   * The hash function is meant to be lightweight as opposed to strong,
   * and was vaguely inspired by ppc64 firmware-supported inverted
   * pagetable hash functions, but uses a full hashtable full of finite
   * collision chains, not just pairs of them.
   *

   * -- nyc

   */
  static void __profile_flip_buffers(void *unused)
  {
  	int cpu = smp_processor_id();
  
  	per_cpu(cpu_profile_flip, cpu) = !per_cpu(cpu_profile_flip, cpu);
  }
  
  static void profile_flip_buffers(void)
  {
  	int i, j, cpu;

  	mutex_lock(&profile_flip_mutex);

  	j = per_cpu(cpu_profile_flip, get_cpu());
  	put_cpu();

  	on_each_cpu(__profile_flip_buffers, NULL, 1);

  	for_each_online_cpu(cpu) {
  		struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[j];
  		for (i = 0; i < NR_PROFILE_HIT; ++i) {
  			if (!hits[i].hits) {
  				if (hits[i].pc)
  					hits[i].pc = 0;
  				continue;
  			}
  			atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
  			hits[i].hits = hits[i].pc = 0;
  		}
  	}

  	mutex_unlock(&profile_flip_mutex);

  }
  
  static void profile_discard_flip_buffers(void)
  {
  	int i, cpu;

  	mutex_lock(&profile_flip_mutex);

  	i = per_cpu(cpu_profile_flip, get_cpu());
  	put_cpu();

  	on_each_cpu(__profile_flip_buffers, NULL, 1);

  	for_each_online_cpu(cpu) {
  		struct profile_hit *hits = per_cpu(cpu_profile_hits, cpu)[i];
  		memset(hits, 0, NR_PROFILE_HIT*sizeof(struct profile_hit));
  	}

  	mutex_unlock(&profile_flip_mutex);

  }

  static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)

  {
  	unsigned long primary, secondary, flags, pc = (unsigned long)__pc;
  	int i, j, cpu;
  	struct profile_hit *hits;

  	pc = min((pc - (unsigned long)_stext) >> prof_shift, prof_len - 1);
  	i = primary = (pc & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
  	secondary = (~(pc << 1) & (NR_PROFILE_GRP - 1)) << PROFILE_GRPSHIFT;
  	cpu = get_cpu();
  	hits = per_cpu(cpu_profile_hits, cpu)[per_cpu(cpu_profile_flip, cpu)];
  	if (!hits) {
  		put_cpu();
  		return;
  	}

  	/*
  	 * We buffer the global profiler buffer into a per-CPU
  	 * queue and thus reduce the number of global (and possibly
  	 * NUMA-alien) accesses. The write-queue is self-coalescing:
  	 */

  	local_irq_save(flags);
  	do {
  		for (j = 0; j < PROFILE_GRPSZ; ++j) {
  			if (hits[i + j].pc == pc) {

  				hits[i + j].hits += nr_hits;

  				goto out;
  			} else if (!hits[i + j].hits) {
  				hits[i + j].pc = pc;

  				hits[i + j].hits = nr_hits;

  				goto out;
  			}
  		}
  		i = (i + secondary) & (NR_PROFILE_HIT - 1);
  	} while (i != primary);

  
  	/*
  	 * Add the current hit(s) and flush the write-queue out
  	 * to the global buffer:
  	 */
  	atomic_add(nr_hits, &prof_buffer[pc]);

  	for (i = 0; i < NR_PROFILE_HIT; ++i) {
  		atomic_add(hits[i].hits, &prof_buffer[hits[i].pc]);
  		hits[i].pc = hits[i].hits = 0;
  	}
  out:
  	local_irq_restore(flags);
  	put_cpu();
  }

  static int profile_dead_cpu(unsigned int cpu)

  {

  	struct page *page;

  	int i;

  	if (prof_cpu_mask != NULL)
  		cpumask_clear_cpu(cpu, prof_cpu_mask);
  
  	for (i = 0; i < 2; i++) {
  		if (per_cpu(cpu_profile_hits, cpu)[i]) {
  			page = virt_to_page(per_cpu(cpu_profile_hits, cpu)[i]);
  			per_cpu(cpu_profile_hits, cpu)[i] = NULL;

  			__free_page(page);
  		}

  	}
  	return 0;
  }
  
  static int profile_prepare_cpu(unsigned int cpu)
  {
  	int i, node = cpu_to_mem(cpu);
  	struct page *page;
  
  	per_cpu(cpu_profile_flip, cpu) = 0;
  
  	for (i = 0; i < 2; i++) {
  		if (per_cpu(cpu_profile_hits, cpu)[i])
  			continue;
  
  		page = __alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
  		if (!page) {
  			profile_dead_cpu(cpu);
  			return -ENOMEM;

  		}

  		per_cpu(cpu_profile_hits, cpu)[i] = page_address(page);

  	}

  	return 0;
  }
  
  static int profile_online_cpu(unsigned int cpu)
  {
  	if (prof_cpu_mask != NULL)
  		cpumask_set_cpu(cpu, prof_cpu_mask);
  
  	return 0;

  }

  #else /* !CONFIG_SMP */
  #define profile_flip_buffers()		do { } while (0)
  #define profile_discard_flip_buffers()	do { } while (0)

  static void do_profile_hits(int type, void *__pc, unsigned int nr_hits)

  {
  	unsigned long pc;

  	pc = ((unsigned long)__pc - (unsigned long)_stext) >> prof_shift;

  	atomic_add(nr_hits, &prof_buffer[min(pc, prof_len - 1)]);

  }
  #endif /* !CONFIG_SMP */

  
  void profile_hits(int type, void *__pc, unsigned int nr_hits)
  {
  	if (prof_on != type || !prof_buffer)
  		return;
  	do_profile_hits(type, __pc, nr_hits);
  }

  EXPORT_SYMBOL_GPL(profile_hits);

  void profile_tick(int type)

  {

  	struct pt_regs *regs = get_irq_regs();

  	if (!user_mode(regs) && prof_cpu_mask != NULL &&
  	    cpumask_test_cpu(smp_processor_id(), prof_cpu_mask))

  		profile_hit(type, (void *)profile_pc(regs));
  }
  
  #ifdef CONFIG_PROC_FS
  #include <linux/proc_fs.h>

  #include <linux/seq_file.h>

  #include <linux/uaccess.h>

  static int prof_cpu_mask_proc_show(struct seq_file *m, void *v)

  {

  	seq_printf(m, "%*pb
  ", cpumask_pr_args(prof_cpu_mask));

  	return 0;
  }
  
  static int prof_cpu_mask_proc_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, prof_cpu_mask_proc_show, NULL);

  }

  static ssize_t prof_cpu_mask_proc_write(struct file *file,
  	const char __user *buffer, size_t count, loff_t *pos)

  {

  	cpumask_var_t new_value;

  	int err;

  	if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
  		return -ENOMEM;

  	err = cpumask_parse_user(buffer, count, new_value);
  	if (!err) {

  		cpumask_copy(prof_cpu_mask, new_value);
  		err = count;

  	}
  	free_cpumask_var(new_value);
  	return err;

  }

  static const struct file_operations prof_cpu_mask_proc_fops = {
  	.open		= prof_cpu_mask_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  	.write		= prof_cpu_mask_proc_write,
  };

  void create_prof_cpu_mask(void)

  {

  	/* create /proc/irq/prof_cpu_mask */

  	proc_create("irq/prof_cpu_mask", 0600, NULL, &prof_cpu_mask_proc_fops);

  }
  
  /*
   * This function accesses profiling information. The returned data is
   * binary: the sampling step and the actual contents of the profile
   * buffer. Use of the program readprofile is recommended in order to
   * get meaningful info out of these data.
   */
  static ssize_t
  read_profile(struct file *file, char __user *buf, size_t count, loff_t *ppos)
  {
  	unsigned long p = *ppos;
  	ssize_t read;

  	char *pnt;

  	unsigned int sample_step = 1 << prof_shift;
  
  	profile_flip_buffers();
  	if (p >= (prof_len+1)*sizeof(unsigned int))
  		return 0;
  	if (count > (prof_len+1)*sizeof(unsigned int) - p)
  		count = (prof_len+1)*sizeof(unsigned int) - p;
  	read = 0;
  
  	while (p < sizeof(unsigned int) && count > 0) {

  		if (put_user(*((char *)(&sample_step)+p), buf))

  			return -EFAULT;

  		buf++; p++; count--; read++;
  	}
  	pnt = (char *)prof_buffer + p - sizeof(atomic_t);

  	if (copy_to_user(buf, (void *)pnt, count))

  		return -EFAULT;
  	read += count;
  	*ppos += read;
  	return read;
  }
  
  /*
   * Writing to /proc/profile resets the counters
   *
   * Writing a 'profiling multiplier' value into it also re-sets the profiling
   * interrupt frequency, on architectures that support this.
   */
  static ssize_t write_profile(struct file *file, const char __user *buf,
  			     size_t count, loff_t *ppos)
  {
  #ifdef CONFIG_SMP

  	extern int setup_profiling_timer(unsigned int multiplier);

  
  	if (count == sizeof(int)) {
  		unsigned int multiplier;
  
  		if (copy_from_user(&multiplier, buf, sizeof(int)))
  			return -EFAULT;
  
  		if (setup_profiling_timer(multiplier))
  			return -EINVAL;
  	}
  #endif
  	profile_discard_flip_buffers();
  	memset(prof_buffer, 0, prof_len * sizeof(atomic_t));
  	return count;
  }

  static const struct file_operations proc_profile_operations = {

  	.read		= read_profile,
  	.write		= write_profile,

  	.llseek		= default_llseek,

  };

  int __ref create_proc_profile(void)

  {

  	struct proc_dir_entry *entry;
  #ifdef CONFIG_SMP
  	enum cpuhp_state online_state;

  #endif

  	int err = 0;

  
  	if (!prof_on)
  		return 0;

  #ifdef CONFIG_SMP
  	err = cpuhp_setup_state(CPUHP_PROFILE_PREPARE, "PROFILE_PREPARE",
  				profile_prepare_cpu, profile_dead_cpu);
  	if (err)
  		return err;
  
  	err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "AP_PROFILE_ONLINE",
  				profile_online_cpu, NULL);
  	if (err < 0)
  		goto err_state_prep;
  	online_state = err;
  	err = 0;
  #endif

  	entry = proc_create("profile", S_IWUSR | S_IRUGO,
  			    NULL, &proc_profile_operations);

  	if (!entry)

  		goto err_state_onl;

  	proc_set_size(entry, (1 + prof_len) * sizeof(atomic_t));

  	return err;
  err_state_onl:
  #ifdef CONFIG_SMP
  	cpuhp_remove_state(online_state);
  err_state_prep:
  	cpuhp_remove_state(CPUHP_PROFILE_PREPARE);
  #endif

  	return err;

  }

  subsys_initcall(create_proc_profile);

  #endif /* CONFIG_PROC_FS */