drivers/oprofile/cpu_buffer.c - kernel/msm-4.9 - Gitiles

 /**
  * @file cpu_buffer.c
  *
  * @remark Copyright 2002 OProfile authors
  * @remark Read the file COPYING
  *
  * @author John Levon <levon@movementarian.org>
  * @author Barry Kasindorf <barry.kasindorf@amd.com>
  *
  * Each CPU has a local buffer that stores PC value/event
  * pairs. We also log context switches when we notice them.
  * Eventually each CPU's buffer is processed into the global
  * event buffer by sync_buffer().
  *
  * We use a local buffer for two reasons: an NMI or similar
  * interrupt cannot synchronise, and high sampling rates
  * would lead to catastrophic global synchronisation if
  * a global buffer was used.
  */

 #include <linux/sched.h>
 #include <linux/oprofile.h>
 #include <linux/vmalloc.h>
 #include <linux/errno.h>

 #include "event_buffer.h"
 #include "cpu_buffer.h"
 #include "buffer_sync.h"
 #include "oprof.h"

 DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);

 static void wq_sync_buffer(struct work_struct *work);

 #define DEFAULT_TIMER_EXPIRE (HZ / 10)
 static int work_enabled;

 void free_cpu_buffers(void)
 {
 	int i;

 	for_each_possible_cpu(i) {
 		vfree(per_cpu(cpu_buffer, i).buffer);
 		per_cpu(cpu_buffer, i).buffer = NULL;
 	}
 }

 unsigned long oprofile_get_cpu_buffer_size(void)
 {
 	return fs_cpu_buffer_size;
 }

 void oprofile_cpu_buffer_inc_smpl_lost(void)
 {
 	struct oprofile_cpu_buffer *cpu_buf
 		= &__get_cpu_var(cpu_buffer);

 	cpu_buf->sample_lost_overflow++;
 }

 int alloc_cpu_buffers(void)
 {
 	int i;

 	unsigned long buffer_size = fs_cpu_buffer_size;

 	for_each_possible_cpu(i) {
 		struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

 		b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
 			cpu_to_node(i));
 		if (!b->buffer)
 			goto fail;

 		b->last_task = NULL;
 		b->last_is_kernel = -1;
 		b->tracing = 0;
 		b->buffer_size = buffer_size;
 		b->tail_pos = 0;
 		b->head_pos = 0;
 		b->sample_received = 0;
 		b->sample_lost_overflow = 0;
 		b->backtrace_aborted = 0;
 		b->sample_invalid_eip = 0;
 		b->cpu = i;
 		INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
 	}
 	return 0;

 fail:
 	free_cpu_buffers();
 	return -ENOMEM;
 }

 void start_cpu_work(void)
 {
 	int i;

 	work_enabled = 1;

 	for_each_online_cpu(i) {
 		struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

 		/*
 		 * Spread the work by 1 jiffy per cpu so they dont all
 		 * fire at once.
 		 */
 		schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
 	}
 }

 void end_cpu_work(void)
 {
 	int i;

 	work_enabled = 0;

 	for_each_online_cpu(i) {
 		struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

 		cancel_delayed_work(&b->work);
 	}

 	flush_scheduled_work();
 }

 /* Resets the cpu buffer to a sane state. */
 void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
 {
 	/*
 	 * reset these to invalid values; the next sample collected
 	 * will populate the buffer with proper values to initialize
 	 * the buffer
 	 */
 	cpu_buf->last_is_kernel = -1;
 	cpu_buf->last_task = NULL;
 }

 /* compute number of available slots in cpu_buffer queue */
 static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b)
 {
 	unsigned long head = b->head_pos;
 	unsigned long tail = b->tail_pos;

 	if (tail > head)
 		return (tail - head) - 1;

 	return tail + (b->buffer_size - head) - 1;
 }

 static void increment_head(struct oprofile_cpu_buffer *b)
 {
 	unsigned long new_head = b->head_pos + 1;

 	/*
 	 * Ensure anything written to the slot before we increment is
 	 * visible
 	 */
 	wmb();

 	if (new_head < b->buffer_size)
 		b->head_pos = new_head;
 	else
 		b->head_pos = 0;
 }

 static inline void
 add_sample(struct oprofile_cpu_buffer *cpu_buf,
 	   unsigned long pc, unsigned long event)
 {
 	struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos];
 	entry->eip = pc;
 	entry->event = event;
 	increment_head(cpu_buf);
 }

 static inline void
 add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
 {
 	add_sample(buffer, ESCAPE_CODE, value);
 }

 /* This must be safe from any context. It's safe writing here
  * because of the head/tail separation of the writer and reader
  * of the CPU buffer.
  *
  * is_kernel is needed because on some architectures you cannot
  * tell if you are in kernel or user space simply by looking at
  * pc. We tag this in the buffer by generating kernel enter/exit
  * events whenever is_kernel changes
  */
 static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
 		      int is_kernel, unsigned long event)
 {
 	struct task_struct *task;

 	cpu_buf->sample_received++;

 	if (pc == ESCAPE_CODE) {
 		cpu_buf->sample_invalid_eip++;
 		return 0;
 	}

 	if (nr_available_slots(cpu_buf) < 3) {
 		cpu_buf->sample_lost_overflow++;
 		return 0;
 	}

 	is_kernel = !!is_kernel;

 	task = current;

 	/* notice a switch from user->kernel or vice versa */
 	if (cpu_buf->last_is_kernel != is_kernel) {
 		cpu_buf->last_is_kernel = is_kernel;
 		add_code(cpu_buf, is_kernel);
 	}

 	/* notice a task switch */
 	if (cpu_buf->last_task != task) {
 		cpu_buf->last_task = task;
 		add_code(cpu_buf, (unsigned long)task);
 	}

 	add_sample(cpu_buf, pc, event);
 	return 1;
 }

 static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
 {
 	if (nr_available_slots(cpu_buf) < 4) {
 		cpu_buf->sample_lost_overflow++;
 		return 0;
 	}

 	add_code(cpu_buf, CPU_TRACE_BEGIN);
 	cpu_buf->tracing = 1;
 	return 1;
 }

 static void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
 {
 	cpu_buf->tracing = 0;
 }

 void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
 				unsigned long event, int is_kernel)
 {
 	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

 	if (!backtrace_depth) {
 		log_sample(cpu_buf, pc, is_kernel, event);
 		return;
 	}

 	if (!oprofile_begin_trace(cpu_buf))
 		return;

 	/*
 	 * if log_sample() fail we can't backtrace since we lost the
 	 * source of this event
 	 */
 	if (log_sample(cpu_buf, pc, is_kernel, event))
 		oprofile_ops.backtrace(regs, backtrace_depth);
 	oprofile_end_trace(cpu_buf);
 }

 void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
 {
 	int is_kernel = !user_mode(regs);
 	unsigned long pc = profile_pc(regs);

 	oprofile_add_ext_sample(pc, regs, event, is_kernel);
 }

 #ifdef CONFIG_OPROFILE_IBS

 #define MAX_IBS_SAMPLE_SIZE 14

 void oprofile_add_ibs_sample(struct pt_regs * const regs,
 			     unsigned int * const ibs_sample, int ibs_code)
 {
 	int is_kernel = !user_mode(regs);
 	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
 	struct task_struct *task;

 	cpu_buf->sample_received++;

 	if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
 		/* we can't backtrace since we lost the source of this event */
 		cpu_buf->sample_lost_overflow++;
 		return;
 	}

 	/* notice a switch from user->kernel or vice versa */
 	if (cpu_buf->last_is_kernel != is_kernel) {
 		cpu_buf->last_is_kernel = is_kernel;
 		add_code(cpu_buf, is_kernel);
 	}

 	/* notice a task switch */
 	if (!is_kernel) {
 		task = current;
 		if (cpu_buf->last_task != task) {
 			cpu_buf->last_task = task;
 			add_code(cpu_buf, (unsigned long)task);
 		}
 	}

 	add_code(cpu_buf, ibs_code);
 	add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
 	add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
 	add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);

 	if (ibs_code == IBS_OP_BEGIN) {
 		add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
 		add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
 		add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
 	}

 	if (backtrace_depth)
 		oprofile_ops.backtrace(regs, backtrace_depth);
 }

 #endif

 void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
 {
 	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
 	log_sample(cpu_buf, pc, is_kernel, event);
 }

 void oprofile_add_trace(unsigned long pc)
 {
 	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

 	if (!cpu_buf->tracing)
 		return;

 	if (nr_available_slots(cpu_buf) < 1) {
 		cpu_buf->tracing = 0;
 		cpu_buf->sample_lost_overflow++;
 		return;
 	}

 	/*
 	 * broken frame can give an eip with the same value as an
 	 * escape code, abort the trace if we get it
 	 */
 	if (pc == ESCAPE_CODE) {
 		cpu_buf->tracing = 0;
 		cpu_buf->backtrace_aborted++;
 		return;
 	}

 	add_sample(cpu_buf, pc, 0);
 }

 /*
  * This serves to avoid cpu buffer overflow, and makes sure
  * the task mortuary progresses
  *
  * By using schedule_delayed_work_on and then schedule_delayed_work
  * we guarantee this will stay on the correct cpu
  */
 static void wq_sync_buffer(struct work_struct *work)
 {
 	struct oprofile_cpu_buffer *b =
 		container_of(work, struct oprofile_cpu_buffer, work.work);
 	if (b->cpu != smp_processor_id()) {
 		printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n",
 		       smp_processor_id(), b->cpu);

 		if (!cpu_online(b->cpu)) {
 			cancel_delayed_work(&b->work);
 			return;
 		}
 	}
 	sync_buffer(b->cpu);

 	/* don't re-add the work if we're shutting down */
 	if (work_enabled)
 		schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
 }
	/**
	* @file cpu_buffer.c
	*
	* @remark Copyright 2002 OProfile authors
	* @remark Read the file COPYING
	*
	* @author John Levon <levon@movementarian.org>
	* @author Barry Kasindorf <barry.kasindorf@amd.com>
	*
	* Each CPU has a local buffer that stores PC value/event
	* pairs. We also log context switches when we notice them.
	* Eventually each CPU's buffer is processed into the global
	* event buffer by sync_buffer().
	*
	* We use a local buffer for two reasons: an NMI or similar
	* interrupt cannot synchronise, and high sampling rates
	* would lead to catastrophic global synchronisation if
	* a global buffer was used.
	*/

	#include <linux/sched.h>
	#include <linux/oprofile.h>
	#include <linux/vmalloc.h>
	#include <linux/errno.h>

	#include "event_buffer.h"
	#include "cpu_buffer.h"
	#include "buffer_sync.h"
	#include "oprof.h"

	DEFINE_PER_CPU(struct oprofile_cpu_buffer, cpu_buffer);

	static void wq_sync_buffer(struct work_struct *work);

	#define DEFAULT_TIMER_EXPIRE (HZ / 10)
	static int work_enabled;

	void free_cpu_buffers(void)
	{
	int i;

	for_each_possible_cpu(i) {
	vfree(per_cpu(cpu_buffer, i).buffer);
	per_cpu(cpu_buffer, i).buffer = NULL;
	}
	}

	unsigned long oprofile_get_cpu_buffer_size(void)
	{
	return fs_cpu_buffer_size;
	}

	void oprofile_cpu_buffer_inc_smpl_lost(void)
	{
	struct oprofile_cpu_buffer *cpu_buf
	= &__get_cpu_var(cpu_buffer);

	cpu_buf->sample_lost_overflow++;
	}

	int alloc_cpu_buffers(void)
	{
	int i;

	unsigned long buffer_size = fs_cpu_buffer_size;

	for_each_possible_cpu(i) {
	struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

	b->buffer = vmalloc_node(sizeof(struct op_sample) * buffer_size,
	cpu_to_node(i));
	if (!b->buffer)
	goto fail;

	b->last_task = NULL;
	b->last_is_kernel = -1;
	b->tracing = 0;
	b->buffer_size = buffer_size;
	b->tail_pos = 0;
	b->head_pos = 0;
	b->sample_received = 0;
	b->sample_lost_overflow = 0;
	b->backtrace_aborted = 0;
	b->sample_invalid_eip = 0;
	b->cpu = i;
	INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
	}
	return 0;

	fail:
	free_cpu_buffers();
	return -ENOMEM;
	}

	void start_cpu_work(void)
	{
	int i;

	work_enabled = 1;

	for_each_online_cpu(i) {
	struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

	/*
	* Spread the work by 1 jiffy per cpu so they dont all
	* fire at once.
	*/
	schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
	}
	}

	void end_cpu_work(void)
	{
	int i;

	work_enabled = 0;

	for_each_online_cpu(i) {
	struct oprofile_cpu_buffer *b = &per_cpu(cpu_buffer, i);

	cancel_delayed_work(&b->work);
	}

	flush_scheduled_work();
	}

	/* Resets the cpu buffer to a sane state. */
	void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
	{
	/*
	* reset these to invalid values; the next sample collected
	* will populate the buffer with proper values to initialize
	* the buffer
	*/
	cpu_buf->last_is_kernel = -1;
	cpu_buf->last_task = NULL;
	}

	/* compute number of available slots in cpu_buffer queue */
	static unsigned long nr_available_slots(struct oprofile_cpu_buffer const *b)
	{
	unsigned long head = b->head_pos;
	unsigned long tail = b->tail_pos;

	if (tail > head)
	return (tail - head) - 1;

	return tail + (b->buffer_size - head) - 1;
	}

	static void increment_head(struct oprofile_cpu_buffer *b)
	{
	unsigned long new_head = b->head_pos + 1;

	/*
	* Ensure anything written to the slot before we increment is
	* visible
	*/
	wmb();

	if (new_head < b->buffer_size)
	b->head_pos = new_head;
	else
	b->head_pos = 0;
	}

	static inline void
	add_sample(struct oprofile_cpu_buffer *cpu_buf,
	unsigned long pc, unsigned long event)
	{
	struct op_sample *entry = &cpu_buf->buffer[cpu_buf->head_pos];
	entry->eip = pc;
	entry->event = event;
	increment_head(cpu_buf);
	}

	static inline void
	add_code(struct oprofile_cpu_buffer *buffer, unsigned long value)
	{
	add_sample(buffer, ESCAPE_CODE, value);
	}

	/* This must be safe from any context. It's safe writing here
	* because of the head/tail separation of the writer and reader
	* of the CPU buffer.
	*
	* is_kernel is needed because on some architectures you cannot
	* tell if you are in kernel or user space simply by looking at
	* pc. We tag this in the buffer by generating kernel enter/exit
	* events whenever is_kernel changes
	*/
	static int log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
	int is_kernel, unsigned long event)
	{
	struct task_struct *task;

	cpu_buf->sample_received++;

	if (pc == ESCAPE_CODE) {
	cpu_buf->sample_invalid_eip++;
	return 0;
	}

	if (nr_available_slots(cpu_buf) < 3) {
	cpu_buf->sample_lost_overflow++;
	return 0;
	}

	is_kernel = !!is_kernel;

	task = current;

	/* notice a switch from user->kernel or vice versa */
	if (cpu_buf->last_is_kernel != is_kernel) {
	cpu_buf->last_is_kernel = is_kernel;
	add_code(cpu_buf, is_kernel);
	}

	/* notice a task switch */
	if (cpu_buf->last_task != task) {
	cpu_buf->last_task = task;
	add_code(cpu_buf, (unsigned long)task);
	}

	add_sample(cpu_buf, pc, event);
	return 1;
	}

	static int oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
	{
	if (nr_available_slots(cpu_buf) < 4) {
	cpu_buf->sample_lost_overflow++;
	return 0;
	}

	add_code(cpu_buf, CPU_TRACE_BEGIN);
	cpu_buf->tracing = 1;
	return 1;
	}

	static void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
	{
	cpu_buf->tracing = 0;
	}

	void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
	unsigned long event, int is_kernel)
	{
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

	if (!backtrace_depth) {
	log_sample(cpu_buf, pc, is_kernel, event);
	return;
	}

	if (!oprofile_begin_trace(cpu_buf))
	return;

	/*
	* if log_sample() fail we can't backtrace since we lost the
	* source of this event
	*/
	if (log_sample(cpu_buf, pc, is_kernel, event))
	oprofile_ops.backtrace(regs, backtrace_depth);
	oprofile_end_trace(cpu_buf);
	}

	void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
	{
	int is_kernel = !user_mode(regs);
	unsigned long pc = profile_pc(regs);

	oprofile_add_ext_sample(pc, regs, event, is_kernel);
	}

	#ifdef CONFIG_OPROFILE_IBS

	#define MAX_IBS_SAMPLE_SIZE 14

	void oprofile_add_ibs_sample(struct pt_regs * const regs,
	unsigned int * const ibs_sample, int ibs_code)
	{
	int is_kernel = !user_mode(regs);
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
	struct task_struct *task;

	cpu_buf->sample_received++;

	if (nr_available_slots(cpu_buf) < MAX_IBS_SAMPLE_SIZE) {
	/* we can't backtrace since we lost the source of this event */
	cpu_buf->sample_lost_overflow++;
	return;
	}

	/* notice a switch from user->kernel or vice versa */
	if (cpu_buf->last_is_kernel != is_kernel) {
	cpu_buf->last_is_kernel = is_kernel;
	add_code(cpu_buf, is_kernel);
	}

	/* notice a task switch */
	if (!is_kernel) {
	task = current;
	if (cpu_buf->last_task != task) {
	cpu_buf->last_task = task;
	add_code(cpu_buf, (unsigned long)task);
	}
	}

	add_code(cpu_buf, ibs_code);
	add_sample(cpu_buf, ibs_sample[0], ibs_sample[1]);
	add_sample(cpu_buf, ibs_sample[2], ibs_sample[3]);
	add_sample(cpu_buf, ibs_sample[4], ibs_sample[5]);

	if (ibs_code == IBS_OP_BEGIN) {
	add_sample(cpu_buf, ibs_sample[6], ibs_sample[7]);
	add_sample(cpu_buf, ibs_sample[8], ibs_sample[9]);
	add_sample(cpu_buf, ibs_sample[10], ibs_sample[11]);
	}

	if (backtrace_depth)
	oprofile_ops.backtrace(regs, backtrace_depth);
	}

	#endif

	void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
	{
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);
	log_sample(cpu_buf, pc, is_kernel, event);
	}

	void oprofile_add_trace(unsigned long pc)
	{
	struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(cpu_buffer);

	if (!cpu_buf->tracing)
	return;

	if (nr_available_slots(cpu_buf) < 1) {
	cpu_buf->tracing = 0;
	cpu_buf->sample_lost_overflow++;
	return;
	}

	/*
	* broken frame can give an eip with the same value as an
	* escape code, abort the trace if we get it
	*/
	if (pc == ESCAPE_CODE) {
	cpu_buf->tracing = 0;
	cpu_buf->backtrace_aborted++;
	return;
	}

	add_sample(cpu_buf, pc, 0);
	}

	/*
	* This serves to avoid cpu buffer overflow, and makes sure
	* the task mortuary progresses
	*
	* By using schedule_delayed_work_on and then schedule_delayed_work
	* we guarantee this will stay on the correct cpu
	*/
	static void wq_sync_buffer(struct work_struct *work)
	{
	struct oprofile_cpu_buffer *b =
	container_of(work, struct oprofile_cpu_buffer, work.work);
	if (b->cpu != smp_processor_id()) {
	printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n",
	smp_processor_id(), b->cpu);

	if (!cpu_online(b->cpu)) {
	cancel_delayed_work(&b->work);
	return;
	}
	}
	sync_buffer(b->cpu);

	/* don't re-add the work if we're shutting down */
	if (work_enabled)
	schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
	}