2 * trace event based perf event profiling/tracing
4 * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
5 * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
8 #include <linux/module.h>
9 #include <linux/kprobes.h>
12 DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
13 EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
15 EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
17 static char *perf_trace_buf;
18 static char *perf_trace_buf_nmi;
21 * Force it to be aligned to unsigned long to avoid misaligned accesses
24 typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
27 /* Count the events in use (per event id, not per instance) */
28 static int total_ref_count;
30 static int perf_trace_event_enable(struct ftrace_event_call *event)
35 if (event->perf_refcount++ > 0)
38 if (!total_ref_count) {
39 buf = (char *)alloc_percpu(perf_trace_t);
43 rcu_assign_pointer(perf_trace_buf, buf);
45 buf = (char *)alloc_percpu(perf_trace_t);
49 rcu_assign_pointer(perf_trace_buf_nmi, buf);
52 ret = event->perf_event_enable(event);
59 if (!total_ref_count) {
60 free_percpu(perf_trace_buf_nmi);
61 free_percpu(perf_trace_buf);
62 perf_trace_buf_nmi = NULL;
63 perf_trace_buf = NULL;
66 event->perf_refcount--;
71 int perf_trace_enable(int event_id)
73 struct ftrace_event_call *event;
76 mutex_lock(&event_mutex);
77 list_for_each_entry(event, &ftrace_events, list) {
78 if (event->id == event_id && event->perf_event_enable &&
79 try_module_get(event->mod)) {
80 ret = perf_trace_event_enable(event);
84 mutex_unlock(&event_mutex);
89 static void perf_trace_event_disable(struct ftrace_event_call *event)
93 if (--event->perf_refcount > 0)
96 event->perf_event_disable(event);
98 if (!--total_ref_count) {
100 rcu_assign_pointer(perf_trace_buf, NULL);
102 nmi_buf = perf_trace_buf_nmi;
103 rcu_assign_pointer(perf_trace_buf_nmi, NULL);
106 * Ensure every events in profiling have finished before
107 * releasing the buffers
112 free_percpu(nmi_buf);
116 void perf_trace_disable(int event_id)
118 struct ftrace_event_call *event;
120 mutex_lock(&event_mutex);
121 list_for_each_entry(event, &ftrace_events, list) {
122 if (event->id == event_id) {
123 perf_trace_event_disable(event);
124 module_put(event->mod);
128 mutex_unlock(&event_mutex);
131 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
132 int *rctxp, unsigned long *irq_flags)
134 struct trace_entry *entry;
135 char *trace_buf, *raw_data;
138 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
140 pc = preempt_count();
142 /* Protect the per cpu buffer, begin the rcu read side */
143 local_irq_save(*irq_flags);
145 *rctxp = perf_swevent_get_recursion_context();
149 cpu = smp_processor_id();
152 trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
154 trace_buf = rcu_dereference_sched(perf_trace_buf);
159 raw_data = per_cpu_ptr(trace_buf, cpu);
161 /* zero the dead bytes from align to not leak stack to user */
162 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
164 entry = (struct trace_entry *)raw_data;
165 tracing_generic_entry_update(entry, *irq_flags, pc);
170 perf_swevent_put_recursion_context(*rctxp);
172 local_irq_restore(*irq_flags);
175 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);