kernel/trace/trace_event_perf.c - linux - Git at Google

 /*
  * trace event based perf event profiling/tracing
  *
  * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
  * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
  */

 #include <linux/module.h>
 #include <linux/kprobes.h>
 #include "trace.h"

 static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];

 /*
  * Force it to be aligned to unsigned long to avoid misaligned accesses
  * suprises
  */
 typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
 	perf_trace_t;

 /* Count the events in use (per event id, not per instance) */
 static int	total_ref_count;

 static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
 				 struct perf_event *p_event)
 {
 	/* The ftrace function trace is allowed only for root. */
 	if (ftrace_event_is_function(tp_event) &&
 	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	/* No tracing, just counting, so no obvious leak */
 	if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
 		return 0;

 	/* Some events are ok to be traced by non-root users... */
 	if (p_event->attach_state == PERF_ATTACH_TASK) {
 		if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
 			return 0;
 	}

 	/*
 	 * ...otherwise raw tracepoint data can be a severe data leak,
 	 * only allow root to have these.
 	 */
 	if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
 		return -EPERM;

 	return 0;
 }

 static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
 				struct perf_event *p_event)
 {
 	struct hlist_head __percpu *list;
 	int ret = -ENOMEM;
 	int cpu;

 	p_event->tp_event = tp_event;
 	if (tp_event->perf_refcount++ > 0)
 		return 0;

 	list = alloc_percpu(struct hlist_head);
 	if (!list)
 		goto fail;

 	for_each_possible_cpu(cpu)
 		INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));

 	tp_event->perf_events = list;

 	if (!total_ref_count) {
 		char __percpu *buf;
 		int i;

 		for (i = 0; i < PERF_NR_CONTEXTS; i++) {
 			buf = (char __percpu *)alloc_percpu(perf_trace_t);
 			if (!buf)
 				goto fail;

 			perf_trace_buf[i] = buf;
 		}
 	}

 	ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
 	if (ret)
 		goto fail;

 	total_ref_count++;
 	return 0;

 fail:
 	if (!total_ref_count) {
 		int i;

 		for (i = 0; i < PERF_NR_CONTEXTS; i++) {
 			free_percpu(perf_trace_buf[i]);
 			perf_trace_buf[i] = NULL;
 		}
 	}

 	if (!--tp_event->perf_refcount) {
 		free_percpu(tp_event->perf_events);
 		tp_event->perf_events = NULL;
 	}

 	return ret;
 }

 static void perf_trace_event_unreg(struct perf_event *p_event)
 {
 	struct ftrace_event_call *tp_event = p_event->tp_event;
 	int i;

 	if (--tp_event->perf_refcount > 0)
 		goto out;

 	tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);

 	/*
 	 * Ensure our callback won't be called anymore. The buffers
 	 * will be freed after that.
 	 */
 	tracepoint_synchronize_unregister();

 	free_percpu(tp_event->perf_events);
 	tp_event->perf_events = NULL;

 	if (!--total_ref_count) {
 		for (i = 0; i < PERF_NR_CONTEXTS; i++) {
 			free_percpu(perf_trace_buf[i]);
 			perf_trace_buf[i] = NULL;
 		}
 	}
 out:
 	module_put(tp_event->mod);
 }

 static int perf_trace_event_open(struct perf_event *p_event)
 {
 	struct ftrace_event_call *tp_event = p_event->tp_event;
 	return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
 }

 static void perf_trace_event_close(struct perf_event *p_event)
 {
 	struct ftrace_event_call *tp_event = p_event->tp_event;
 	tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
 }

 static int perf_trace_event_init(struct ftrace_event_call *tp_event,
 				 struct perf_event *p_event)
 {
 	int ret;

 	ret = perf_trace_event_perm(tp_event, p_event);
 	if (ret)
 		return ret;

 	ret = perf_trace_event_reg(tp_event, p_event);
 	if (ret)
 		return ret;

 	ret = perf_trace_event_open(p_event);
 	if (ret) {
 		perf_trace_event_unreg(p_event);
 		return ret;
 	}

 	return 0;
 }

 int perf_trace_init(struct perf_event *p_event)
 {
 	struct ftrace_event_call *tp_event;
 	int event_id = p_event->attr.config;
 	int ret = -EINVAL;

 	mutex_lock(&event_mutex);
 	list_for_each_entry(tp_event, &ftrace_events, list) {
 		if (tp_event->event.type == event_id &&
 		    tp_event->class && tp_event->class->reg &&
 		    try_module_get(tp_event->mod)) {
 			ret = perf_trace_event_init(tp_event, p_event);
 			if (ret)
 				module_put(tp_event->mod);
 			break;
 		}
 	}
 	mutex_unlock(&event_mutex);

 	return ret;
 }

 void perf_trace_destroy(struct perf_event *p_event)
 {
 	mutex_lock(&event_mutex);
 	perf_trace_event_close(p_event);
 	perf_trace_event_unreg(p_event);
 	mutex_unlock(&event_mutex);
 }

 int perf_trace_add(struct perf_event *p_event, int flags)
 {
 	struct ftrace_event_call *tp_event = p_event->tp_event;
 	struct hlist_head __percpu *pcpu_list;
 	struct hlist_head *list;

 	pcpu_list = tp_event->perf_events;
 	if (WARN_ON_ONCE(!pcpu_list))
 		return -EINVAL;

 	if (!(flags & PERF_EF_START))
 		p_event->hw.state = PERF_HES_STOPPED;

 	list = this_cpu_ptr(pcpu_list);
 	hlist_add_head_rcu(&p_event->hlist_entry, list);

 	return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
 }

 void perf_trace_del(struct perf_event *p_event, int flags)
 {
 	struct ftrace_event_call *tp_event = p_event->tp_event;
 	hlist_del_rcu(&p_event->hlist_entry);
 	tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
 }

 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
 				       struct pt_regs *regs, int *rctxp)
 {
 	struct trace_entry *entry;
 	unsigned long flags;
 	char *raw_data;
 	int pc;

 	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));

 	pc = preempt_count();

 	*rctxp = perf_swevent_get_recursion_context();
 	if (*rctxp < 0)
 		return NULL;

 	raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);

 	/* zero the dead bytes from align to not leak stack to user */
 	memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));

 	entry = (struct trace_entry *)raw_data;
 	local_save_flags(flags);
 	tracing_generic_entry_update(entry, flags, pc);
 	entry->type = type;

 	return raw_data;
 }
 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);

 #ifdef CONFIG_FUNCTION_TRACER
 static void
 perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
 {
 	struct ftrace_entry *entry;
 	struct hlist_head *head;
 	struct pt_regs regs;
 	int rctx;

 #define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
 		    sizeof(u64)) - sizeof(u32))

 	BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);

 	perf_fetch_caller_regs(&regs);

 	entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
 	if (!entry)
 		return;

 	entry->ip = ip;
 	entry->parent_ip = parent_ip;

 	head = this_cpu_ptr(event_function.perf_events);
 	perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
 			      1, &regs, head, NULL);

 #undef ENTRY_SIZE
 }

 static int perf_ftrace_function_register(struct perf_event *event)
 {
 	struct ftrace_ops *ops = &event->ftrace_ops;

 	ops->flags |= FTRACE_OPS_FL_CONTROL;
 	ops->func = perf_ftrace_function_call;
 	return register_ftrace_function(ops);
 }

 static int perf_ftrace_function_unregister(struct perf_event *event)
 {
 	struct ftrace_ops *ops = &event->ftrace_ops;
 	int ret = unregister_ftrace_function(ops);
 	ftrace_free_filter(ops);
 	return ret;
 }

 static void perf_ftrace_function_enable(struct perf_event *event)
 {
 	ftrace_function_local_enable(&event->ftrace_ops);
 }

 static void perf_ftrace_function_disable(struct perf_event *event)
 {
 	ftrace_function_local_disable(&event->ftrace_ops);
 }

 int perf_ftrace_event_register(struct ftrace_event_call *call,
 			       enum trace_reg type, void *data)
 {
 	switch (type) {
 	case TRACE_REG_REGISTER:
 	case TRACE_REG_UNREGISTER:
 		break;
 	case TRACE_REG_PERF_REGISTER:
 	case TRACE_REG_PERF_UNREGISTER:
 		return 0;
 	case TRACE_REG_PERF_OPEN:
 		return perf_ftrace_function_register(data);
 	case TRACE_REG_PERF_CLOSE:
 		return perf_ftrace_function_unregister(data);
 	case TRACE_REG_PERF_ADD:
 		perf_ftrace_function_enable(data);
 		return 0;
 	case TRACE_REG_PERF_DEL:
 		perf_ftrace_function_disable(data);
 		return 0;
 	}

 	return -EINVAL;
 }
 #endif /* CONFIG_FUNCTION_TRACER */
	/*
	* trace event based perf event profiling/tracing
	*
	* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
	* Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
	*/

	#include <linux/module.h>
	#include <linux/kprobes.h>
	#include "trace.h"

	static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];

	/*
	* Force it to be aligned to unsigned long to avoid misaligned accesses
	* suprises
	*/
	typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
	perf_trace_t;

	/* Count the events in use (per event id, not per instance) */
	static int total_ref_count;

	static int perf_trace_event_perm(struct ftrace_event_call *tp_event,
	struct perf_event *p_event)
	{
	/* The ftrace function trace is allowed only for root. */
	if (ftrace_event_is_function(tp_event) &&
	perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
	return -EPERM;

	/* No tracing, just counting, so no obvious leak */
	if (!(p_event->attr.sample_type & PERF_SAMPLE_RAW))
	return 0;

	/* Some events are ok to be traced by non-root users... */
	if (p_event->attach_state == PERF_ATTACH_TASK) {
	if (tp_event->flags & TRACE_EVENT_FL_CAP_ANY)
	return 0;
	}

	/*
	* ...otherwise raw tracepoint data can be a severe data leak,
	* only allow root to have these.
	*/
	if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
	return -EPERM;

	return 0;
	}

	static int perf_trace_event_reg(struct ftrace_event_call *tp_event,
	struct perf_event *p_event)
	{
	struct hlist_head __percpu *list;
	int ret = -ENOMEM;
	int cpu;

	p_event->tp_event = tp_event;
	if (tp_event->perf_refcount++ > 0)
	return 0;

	list = alloc_percpu(struct hlist_head);
	if (!list)
	goto fail;

	for_each_possible_cpu(cpu)
	INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));

	tp_event->perf_events = list;

	if (!total_ref_count) {
	char __percpu *buf;
	int i;

	for (i = 0; i < PERF_NR_CONTEXTS; i++) {
	buf = (char __percpu *)alloc_percpu(perf_trace_t);
	if (!buf)
	goto fail;

	perf_trace_buf[i] = buf;
	}
	}

	ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER, NULL);
	if (ret)
	goto fail;

	total_ref_count++;
	return 0;

	fail:
	if (!total_ref_count) {
	int i;

	for (i = 0; i < PERF_NR_CONTEXTS; i++) {
	free_percpu(perf_trace_buf[i]);
	perf_trace_buf[i] = NULL;
	}
	}

	if (!--tp_event->perf_refcount) {
	free_percpu(tp_event->perf_events);
	tp_event->perf_events = NULL;
	}

	return ret;
	}

	static void perf_trace_event_unreg(struct perf_event *p_event)
	{
	struct ftrace_event_call *tp_event = p_event->tp_event;
	int i;

	if (--tp_event->perf_refcount > 0)
	goto out;

	tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER, NULL);

	/*
	* Ensure our callback won't be called anymore. The buffers
	* will be freed after that.
	*/
	tracepoint_synchronize_unregister();

	free_percpu(tp_event->perf_events);
	tp_event->perf_events = NULL;

	if (!--total_ref_count) {
	for (i = 0; i < PERF_NR_CONTEXTS; i++) {
	free_percpu(perf_trace_buf[i]);
	perf_trace_buf[i] = NULL;
	}
	}
	out:
	module_put(tp_event->mod);
	}

	static int perf_trace_event_open(struct perf_event *p_event)
	{
	struct ftrace_event_call *tp_event = p_event->tp_event;
	return tp_event->class->reg(tp_event, TRACE_REG_PERF_OPEN, p_event);
	}

	static void perf_trace_event_close(struct perf_event *p_event)
	{
	struct ftrace_event_call *tp_event = p_event->tp_event;
	tp_event->class->reg(tp_event, TRACE_REG_PERF_CLOSE, p_event);
	}

	static int perf_trace_event_init(struct ftrace_event_call *tp_event,
	struct perf_event *p_event)
	{
	int ret;

	ret = perf_trace_event_perm(tp_event, p_event);
	if (ret)
	return ret;

	ret = perf_trace_event_reg(tp_event, p_event);
	if (ret)
	return ret;

	ret = perf_trace_event_open(p_event);
	if (ret) {
	perf_trace_event_unreg(p_event);
	return ret;
	}

	return 0;
	}

	int perf_trace_init(struct perf_event *p_event)
	{
	struct ftrace_event_call *tp_event;
	int event_id = p_event->attr.config;
	int ret = -EINVAL;

	mutex_lock(&event_mutex);
	list_for_each_entry(tp_event, &ftrace_events, list) {
	if (tp_event->event.type == event_id &&
	tp_event->class && tp_event->class->reg &&
	try_module_get(tp_event->mod)) {
	ret = perf_trace_event_init(tp_event, p_event);
	if (ret)
	module_put(tp_event->mod);
	break;
	}
	}
	mutex_unlock(&event_mutex);

	return ret;
	}

	void perf_trace_destroy(struct perf_event *p_event)
	{
	mutex_lock(&event_mutex);
	perf_trace_event_close(p_event);
	perf_trace_event_unreg(p_event);
	mutex_unlock(&event_mutex);
	}

	int perf_trace_add(struct perf_event *p_event, int flags)
	{
	struct ftrace_event_call *tp_event = p_event->tp_event;
	struct hlist_head __percpu *pcpu_list;
	struct hlist_head *list;

	pcpu_list = tp_event->perf_events;
	if (WARN_ON_ONCE(!pcpu_list))
	return -EINVAL;

	if (!(flags & PERF_EF_START))
	p_event->hw.state = PERF_HES_STOPPED;

	list = this_cpu_ptr(pcpu_list);
	hlist_add_head_rcu(&p_event->hlist_entry, list);

	return tp_event->class->reg(tp_event, TRACE_REG_PERF_ADD, p_event);
	}

	void perf_trace_del(struct perf_event *p_event, int flags)
	{
	struct ftrace_event_call *tp_event = p_event->tp_event;
	hlist_del_rcu(&p_event->hlist_entry);
	tp_event->class->reg(tp_event, TRACE_REG_PERF_DEL, p_event);
	}

	__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
	struct pt_regs regs, int rctxp)
	{
	struct trace_entry *entry;
	unsigned long flags;
	char *raw_data;
	int pc;

	BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));

	pc = preempt_count();

	*rctxp = perf_swevent_get_recursion_context();
	if (*rctxp < 0)
	return NULL;

	raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);

	/* zero the dead bytes from align to not leak stack to user */
	memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));

	entry = (struct trace_entry *)raw_data;
	local_save_flags(flags);
	tracing_generic_entry_update(entry, flags, pc);
	entry->type = type;

	return raw_data;
	}
	EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);

	#ifdef CONFIG_FUNCTION_TRACER
	static void
	perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip)
	{
	struct ftrace_entry *entry;
	struct hlist_head *head;
	struct pt_regs regs;
	int rctx;

	#define ENTRY_SIZE (ALIGN(sizeof(struct ftrace_entry) + sizeof(u32), \
	sizeof(u64)) - sizeof(u32))

	BUILD_BUG_ON(ENTRY_SIZE > PERF_MAX_TRACE_SIZE);

	perf_fetch_caller_regs(&regs);

	entry = perf_trace_buf_prepare(ENTRY_SIZE, TRACE_FN, NULL, &rctx);
	if (!entry)
	return;

	entry->ip = ip;
	entry->parent_ip = parent_ip;

	head = this_cpu_ptr(event_function.perf_events);
	perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, 0,
	1, &regs, head, NULL);

	#undef ENTRY_SIZE
	}

	static int perf_ftrace_function_register(struct perf_event *event)
	{
	struct ftrace_ops *ops = &event->ftrace_ops;

	ops->flags \|= FTRACE_OPS_FL_CONTROL;
	ops->func = perf_ftrace_function_call;
	return register_ftrace_function(ops);
	}

	static int perf_ftrace_function_unregister(struct perf_event *event)
	{
	struct ftrace_ops *ops = &event->ftrace_ops;
	int ret = unregister_ftrace_function(ops);
	ftrace_free_filter(ops);
	return ret;
	}

	static void perf_ftrace_function_enable(struct perf_event *event)
	{
	ftrace_function_local_enable(&event->ftrace_ops);
	}

	static void perf_ftrace_function_disable(struct perf_event *event)
	{
	ftrace_function_local_disable(&event->ftrace_ops);
	}

	int perf_ftrace_event_register(struct ftrace_event_call *call,
	enum trace_reg type, void *data)
	{
	switch (type) {
	case TRACE_REG_REGISTER:
	case TRACE_REG_UNREGISTER:
	break;
	case TRACE_REG_PERF_REGISTER:
	case TRACE_REG_PERF_UNREGISTER:
	return 0;
	case TRACE_REG_PERF_OPEN:
	return perf_ftrace_function_register(data);
	case TRACE_REG_PERF_CLOSE:
	return perf_ftrace_function_unregister(data);
	case TRACE_REG_PERF_ADD:
	perf_ftrace_function_enable(data);
	return 0;
	case TRACE_REG_PERF_DEL:
	perf_ftrace_function_disable(data);
	return 0;
	}

	return -EINVAL;
	}
	#endif /* CONFIG_FUNCTION_TRACER */