121 lines
2.4 KiB
C
121 lines
2.4 KiB
C
/*
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* trace event based perf counter profiling
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*
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* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
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*
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*/
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#include <linux/module.h>
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#include "trace.h"
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/*
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* We can't use a size but a type in alloc_percpu()
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* So let's create a dummy type that matches the desired size
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*/
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typedef struct {char buf[FTRACE_MAX_PROFILE_SIZE];} profile_buf_t;
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char *trace_profile_buf;
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EXPORT_SYMBOL_GPL(trace_profile_buf);
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char *trace_profile_buf_nmi;
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EXPORT_SYMBOL_GPL(trace_profile_buf_nmi);
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/* Count the events in use (per event id, not per instance) */
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static int total_profile_count;
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static int ftrace_profile_enable_event(struct ftrace_event_call *event)
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{
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char *buf;
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int ret = -ENOMEM;
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if (atomic_inc_return(&event->profile_count))
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return 0;
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if (!total_profile_count++) {
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buf = (char *)alloc_percpu(profile_buf_t);
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if (!buf)
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goto fail_buf;
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rcu_assign_pointer(trace_profile_buf, buf);
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buf = (char *)alloc_percpu(profile_buf_t);
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if (!buf)
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goto fail_buf_nmi;
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rcu_assign_pointer(trace_profile_buf_nmi, buf);
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}
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ret = event->profile_enable();
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if (!ret)
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return 0;
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kfree(trace_profile_buf_nmi);
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fail_buf_nmi:
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kfree(trace_profile_buf);
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fail_buf:
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total_profile_count--;
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atomic_dec(&event->profile_count);
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return ret;
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}
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int ftrace_profile_enable(int event_id)
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{
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struct ftrace_event_call *event;
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int ret = -EINVAL;
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mutex_lock(&event_mutex);
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list_for_each_entry(event, &ftrace_events, list) {
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if (event->id == event_id && event->profile_enable &&
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try_module_get(event->mod)) {
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ret = ftrace_profile_enable_event(event);
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break;
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}
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}
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mutex_unlock(&event_mutex);
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return ret;
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}
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static void ftrace_profile_disable_event(struct ftrace_event_call *event)
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{
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char *buf, *nmi_buf;
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if (!atomic_add_negative(-1, &event->profile_count))
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return;
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event->profile_disable();
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if (!--total_profile_count) {
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buf = trace_profile_buf;
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rcu_assign_pointer(trace_profile_buf, NULL);
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nmi_buf = trace_profile_buf_nmi;
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rcu_assign_pointer(trace_profile_buf_nmi, NULL);
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/*
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* Ensure every events in profiling have finished before
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* releasing the buffers
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*/
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synchronize_sched();
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free_percpu(buf);
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free_percpu(nmi_buf);
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}
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}
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void ftrace_profile_disable(int event_id)
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{
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struct ftrace_event_call *event;
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mutex_lock(&event_mutex);
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list_for_each_entry(event, &ftrace_events, list) {
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if (event->id == event_id) {
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ftrace_profile_disable_event(event);
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module_put(event->mod);
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break;
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}
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}
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mutex_unlock(&event_mutex);
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}
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