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 static char __percpu *perf_trace_buf[PERF_NR_CONTEXTS];
15 * Force it to be aligned to unsigned long to avoid misaligned accesses
18 typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
21 /* Count the events in use (per event id, not per instance) */
22 static int total_ref_count;
24 static int perf_trace_event_init(struct ftrace_event_call *tp_event,
25 struct perf_event *p_event)
27 struct hlist_head __percpu *list;
31 p_event->tp_event = tp_event;
32 if (tp_event->perf_refcount++ > 0)
35 list = alloc_percpu(struct hlist_head);
39 for_each_possible_cpu(cpu)
40 INIT_HLIST_HEAD(per_cpu_ptr(list, cpu));
42 tp_event->perf_events = list;
44 if (!total_ref_count) {
48 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
49 buf = (char __percpu *)alloc_percpu(perf_trace_t);
53 perf_trace_buf[i] = buf;
57 ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER);
65 if (!total_ref_count) {
68 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
69 free_percpu(perf_trace_buf[i]);
70 perf_trace_buf[i] = NULL;
74 if (!--tp_event->perf_refcount) {
75 free_percpu(tp_event->perf_events);
76 tp_event->perf_events = NULL;
82 int perf_trace_init(struct perf_event *p_event)
84 struct ftrace_event_call *tp_event;
85 int event_id = p_event->attr.config;
88 mutex_lock(&event_mutex);
89 list_for_each_entry(tp_event, &ftrace_events, list) {
90 if (tp_event->event.type == event_id &&
91 tp_event->class && tp_event->class->reg &&
92 try_module_get(tp_event->mod)) {
93 ret = perf_trace_event_init(tp_event, p_event);
97 mutex_unlock(&event_mutex);
102 int perf_trace_enable(struct perf_event *p_event)
104 struct ftrace_event_call *tp_event = p_event->tp_event;
105 struct hlist_head __percpu *pcpu_list;
106 struct hlist_head *list;
108 pcpu_list = tp_event->perf_events;
109 if (WARN_ON_ONCE(!pcpu_list))
112 list = this_cpu_ptr(pcpu_list);
113 hlist_add_head_rcu(&p_event->hlist_entry, list);
118 void perf_trace_disable(struct perf_event *p_event)
120 hlist_del_rcu(&p_event->hlist_entry);
123 void perf_trace_destroy(struct perf_event *p_event)
125 struct ftrace_event_call *tp_event = p_event->tp_event;
128 mutex_lock(&event_mutex);
129 if (--tp_event->perf_refcount > 0)
132 tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER);
135 * Ensure our callback won't be called anymore. The buffers
136 * will be freed after that.
138 tracepoint_synchronize_unregister();
140 free_percpu(tp_event->perf_events);
141 tp_event->perf_events = NULL;
143 if (!--total_ref_count) {
144 for (i = 0; i < PERF_NR_CONTEXTS; i++) {
145 free_percpu(perf_trace_buf[i]);
146 perf_trace_buf[i] = NULL;
150 mutex_unlock(&event_mutex);
153 __kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
154 struct pt_regs *regs, int *rctxp)
156 struct trace_entry *entry;
161 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
163 pc = preempt_count();
165 *rctxp = perf_swevent_get_recursion_context();
169 raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]);
171 /* zero the dead bytes from align to not leak stack to user */
172 memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
174 entry = (struct trace_entry *)raw_data;
175 local_save_flags(flags);
176 tracing_generic_entry_update(entry, flags, pc);
181 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);