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 *perf_trace_buf
[4];
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
*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
< 4; i
++) {
49 buf
= (char *)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
< 4; 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
*list
;
107 list
= tp_event
->perf_events
;
108 if (WARN_ON_ONCE(!list
))
111 list
= this_cpu_ptr(list
);
112 hlist_add_head_rcu(&p_event
->hlist_entry
, list
);
117 void perf_trace_disable(struct perf_event
*p_event
)
119 hlist_del_rcu(&p_event
->hlist_entry
);
122 void perf_trace_destroy(struct perf_event
*p_event
)
124 struct ftrace_event_call
*tp_event
= p_event
->tp_event
;
127 mutex_lock(&event_mutex
);
128 if (--tp_event
->perf_refcount
> 0)
131 tp_event
->class->reg(tp_event
, TRACE_REG_PERF_UNREGISTER
);
134 * Ensure our callback won't be called anymore. The buffers
135 * will be freed after that.
137 tracepoint_synchronize_unregister();
139 free_percpu(tp_event
->perf_events
);
140 tp_event
->perf_events
= NULL
;
142 if (!--total_ref_count
) {
143 for (i
= 0; i
< 4; i
++) {
144 free_percpu(perf_trace_buf
[i
]);
145 perf_trace_buf
[i
] = NULL
;
149 mutex_unlock(&event_mutex
);
152 __kprobes
void *perf_trace_buf_prepare(int size
, unsigned short type
,
153 struct pt_regs
*regs
, int *rctxp
)
155 struct trace_entry
*entry
;
160 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE
% sizeof(unsigned long));
162 pc
= preempt_count();
164 *rctxp
= perf_swevent_get_recursion_context();
168 raw_data
= this_cpu_ptr(perf_trace_buf
[*rctxp
]);
170 /* zero the dead bytes from align to not leak stack to user */
171 memset(&raw_data
[size
- sizeof(u64
)], 0, sizeof(u64
));
173 entry
= (struct trace_entry
*)raw_data
;
174 local_save_flags(flags
);
175 tracing_generic_entry_update(entry
, flags
, pc
);
180 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare
);