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 EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs
);
14 static char *perf_trace_buf
[4];
17 * Force it to be aligned to unsigned long to avoid misaligned accesses
20 typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE
/ sizeof(unsigned long)])
23 /* Count the events in use (per event id, not per instance) */
24 static int total_ref_count
;
26 static int perf_trace_event_init(struct ftrace_event_call
*tp_event
,
27 struct perf_event
*p_event
)
29 struct hlist_head
*list
;
33 p_event
->tp_event
= tp_event
;
34 if (tp_event
->perf_refcount
++ > 0)
37 list
= alloc_percpu(struct hlist_head
);
41 for_each_possible_cpu(cpu
)
42 INIT_HLIST_HEAD(per_cpu_ptr(list
, cpu
));
44 tp_event
->perf_events
= list
;
46 if (!total_ref_count
) {
50 for (i
= 0; i
< 4; i
++) {
51 buf
= (char *)alloc_percpu(perf_trace_t
);
55 perf_trace_buf
[i
] = buf
;
59 if (tp_event
->class->reg
)
60 ret
= tp_event
->class->reg(tp_event
, TRACE_REG_PERF_REGISTER
);
62 ret
= tracepoint_probe_register(tp_event
->name
,
63 tp_event
->class->perf_probe
,
73 if (!total_ref_count
) {
76 for (i
= 0; i
< 4; i
++) {
77 free_percpu(perf_trace_buf
[i
]);
78 perf_trace_buf
[i
] = NULL
;
82 if (!--tp_event
->perf_refcount
) {
83 free_percpu(tp_event
->perf_events
);
84 tp_event
->perf_events
= NULL
;
90 int perf_trace_init(struct perf_event
*p_event
)
92 struct ftrace_event_call
*tp_event
;
93 int event_id
= p_event
->attr
.config
;
96 mutex_lock(&event_mutex
);
97 list_for_each_entry(tp_event
, &ftrace_events
, list
) {
98 if (tp_event
->event
.type
== event_id
&&
99 tp_event
->class && tp_event
->class->perf_probe
&&
100 try_module_get(tp_event
->mod
)) {
101 ret
= perf_trace_event_init(tp_event
, p_event
);
105 mutex_unlock(&event_mutex
);
110 int perf_trace_enable(struct perf_event
*p_event
)
112 struct ftrace_event_call
*tp_event
= p_event
->tp_event
;
113 struct hlist_head
*list
;
115 list
= tp_event
->perf_events
;
116 if (WARN_ON_ONCE(!list
))
119 list
= per_cpu_ptr(list
, smp_processor_id());
120 hlist_add_head_rcu(&p_event
->hlist_entry
, list
);
125 void perf_trace_disable(struct perf_event
*p_event
)
127 hlist_del_rcu(&p_event
->hlist_entry
);
130 void perf_trace_destroy(struct perf_event
*p_event
)
132 struct ftrace_event_call
*tp_event
= p_event
->tp_event
;
135 if (--tp_event
->perf_refcount
> 0)
138 if (tp_event
->class->reg
)
139 tp_event
->class->reg(tp_event
, TRACE_REG_PERF_UNREGISTER
);
141 tracepoint_probe_unregister(tp_event
->name
,
142 tp_event
->class->perf_probe
,
145 free_percpu(tp_event
->perf_events
);
146 tp_event
->perf_events
= NULL
;
148 if (!--total_ref_count
) {
149 for (i
= 0; i
< 4; i
++) {
150 free_percpu(perf_trace_buf
[i
]);
151 perf_trace_buf
[i
] = NULL
;
156 __kprobes
void *perf_trace_buf_prepare(int size
, unsigned short type
,
157 struct pt_regs
*regs
, int *rctxp
)
159 struct trace_entry
*entry
;
164 BUILD_BUG_ON(PERF_MAX_TRACE_SIZE
% sizeof(unsigned long));
166 pc
= preempt_count();
168 *rctxp
= perf_swevent_get_recursion_context();
172 raw_data
= per_cpu_ptr(perf_trace_buf
[*rctxp
], smp_processor_id());
174 /* zero the dead bytes from align to not leak stack to user */
175 memset(&raw_data
[size
- sizeof(u64
)], 0, sizeof(u64
));
177 entry
= (struct trace_entry
*)raw_data
;
178 local_save_flags(flags
);
179 tracing_generic_entry_update(entry
, flags
, pc
);
184 EXPORT_SYMBOL_GPL(perf_trace_buf_prepare
);