Commit | Line | Data |
---|---|---|
ac199db0 | 1 | /* |
97d5a220 | 2 | * trace event based perf event profiling/tracing |
ac199db0 PZ |
3 | * |
4 | * Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com> | |
c530665c | 5 | * Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com> |
ac199db0 PZ |
6 | */ |
7 | ||
558e6547 | 8 | #include <linux/module.h> |
430ad5a6 | 9 | #include <linux/kprobes.h> |
ac199db0 PZ |
10 | #include "trace.h" |
11 | ||
dcd5c166 | 12 | EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs); |
20ab4425 | 13 | |
b7e2ecef | 14 | static char *perf_trace_buf[4]; |
20ab4425 | 15 | |
eb1e7961 FW |
16 | /* |
17 | * Force it to be aligned to unsigned long to avoid misaligned accesses | |
18 | * suprises | |
19 | */ | |
20 | typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)]) | |
21 | perf_trace_t; | |
ce71b9df | 22 | |
20ab4425 | 23 | /* Count the events in use (per event id, not per instance) */ |
97d5a220 | 24 | static int total_ref_count; |
20ab4425 | 25 | |
4f41c013 | 26 | static int perf_trace_event_enable(struct ftrace_event_call *event, void *data) |
e5e25cf4 | 27 | { |
20ab4425 FW |
28 | int ret = -ENOMEM; |
29 | ||
4f41c013 PZ |
30 | if (event->perf_refcount++ > 0) { |
31 | event->perf_data = NULL; | |
e5e25cf4 | 32 | return 0; |
4f41c013 | 33 | } |
e5e25cf4 | 34 | |
97d5a220 | 35 | if (!total_ref_count) { |
b7e2ecef PZ |
36 | char *buf; |
37 | int i; | |
20ab4425 | 38 | |
b7e2ecef PZ |
39 | for (i = 0; i < 4; i++) { |
40 | buf = (char *)alloc_percpu(perf_trace_t); | |
41 | if (!buf) | |
42 | goto fail_buf; | |
20ab4425 | 43 | |
b7e2ecef PZ |
44 | rcu_assign_pointer(perf_trace_buf[i], buf); |
45 | } | |
20ab4425 FW |
46 | } |
47 | ||
97d5a220 | 48 | ret = event->perf_event_enable(event); |
fe8e5b5a | 49 | if (!ret) { |
4f41c013 | 50 | event->perf_data = data; |
97d5a220 | 51 | total_ref_count++; |
20ab4425 | 52 | return 0; |
fe8e5b5a | 53 | } |
20ab4425 | 54 | |
b7e2ecef | 55 | fail_buf: |
97d5a220 | 56 | if (!total_ref_count) { |
b7e2ecef PZ |
57 | int i; |
58 | ||
59 | for (i = 0; i < 4; i++) { | |
60 | free_percpu(perf_trace_buf[i]); | |
61 | perf_trace_buf[i] = NULL; | |
62 | } | |
fe8e5b5a | 63 | } |
97d5a220 | 64 | event->perf_refcount--; |
20ab4425 FW |
65 | |
66 | return ret; | |
e5e25cf4 FW |
67 | } |
68 | ||
4f41c013 | 69 | int perf_trace_enable(int event_id, void *data) |
ac199db0 PZ |
70 | { |
71 | struct ftrace_event_call *event; | |
20c8928a | 72 | int ret = -EINVAL; |
ac199db0 | 73 | |
20c8928a | 74 | mutex_lock(&event_mutex); |
a59fd602 | 75 | list_for_each_entry(event, &ftrace_events, list) { |
97d5a220 | 76 | if (event->id == event_id && event->perf_event_enable && |
558e6547 | 77 | try_module_get(event->mod)) { |
4f41c013 | 78 | ret = perf_trace_event_enable(event, data); |
20c8928a LZ |
79 | break; |
80 | } | |
ac199db0 | 81 | } |
20c8928a | 82 | mutex_unlock(&event_mutex); |
ac199db0 | 83 | |
20c8928a | 84 | return ret; |
ac199db0 PZ |
85 | } |
86 | ||
97d5a220 | 87 | static void perf_trace_event_disable(struct ftrace_event_call *event) |
e5e25cf4 | 88 | { |
97d5a220 | 89 | if (--event->perf_refcount > 0) |
e5e25cf4 FW |
90 | return; |
91 | ||
97d5a220 | 92 | event->perf_event_disable(event); |
20ab4425 | 93 | |
97d5a220 | 94 | if (!--total_ref_count) { |
b7e2ecef PZ |
95 | char *buf[4]; |
96 | int i; | |
20ab4425 | 97 | |
b7e2ecef PZ |
98 | for (i = 0; i < 4; i++) { |
99 | buf[i] = perf_trace_buf[i]; | |
100 | rcu_assign_pointer(perf_trace_buf[i], NULL); | |
101 | } | |
20ab4425 FW |
102 | |
103 | /* | |
104 | * Ensure every events in profiling have finished before | |
105 | * releasing the buffers | |
106 | */ | |
107 | synchronize_sched(); | |
108 | ||
b7e2ecef PZ |
109 | for (i = 0; i < 4; i++) |
110 | free_percpu(buf[i]); | |
20ab4425 | 111 | } |
e5e25cf4 FW |
112 | } |
113 | ||
97d5a220 | 114 | void perf_trace_disable(int event_id) |
ac199db0 PZ |
115 | { |
116 | struct ftrace_event_call *event; | |
117 | ||
20c8928a | 118 | mutex_lock(&event_mutex); |
a59fd602 | 119 | list_for_each_entry(event, &ftrace_events, list) { |
20c8928a | 120 | if (event->id == event_id) { |
97d5a220 | 121 | perf_trace_event_disable(event); |
558e6547 | 122 | module_put(event->mod); |
20c8928a LZ |
123 | break; |
124 | } | |
ac199db0 | 125 | } |
20c8928a | 126 | mutex_unlock(&event_mutex); |
ac199db0 | 127 | } |
430ad5a6 | 128 | |
97d5a220 | 129 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
b7e2ecef | 130 | struct pt_regs *regs, int *rctxp) |
430ad5a6 XG |
131 | { |
132 | struct trace_entry *entry; | |
133 | char *trace_buf, *raw_data; | |
b7e2ecef | 134 | int pc; |
430ad5a6 | 135 | |
eb1e7961 FW |
136 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
137 | ||
430ad5a6 XG |
138 | pc = preempt_count(); |
139 | ||
430ad5a6 XG |
140 | *rctxp = perf_swevent_get_recursion_context(); |
141 | if (*rctxp < 0) | |
142 | goto err_recursion; | |
143 | ||
b7e2ecef | 144 | trace_buf = rcu_dereference_sched(perf_trace_buf[*rctxp]); |
430ad5a6 XG |
145 | if (!trace_buf) |
146 | goto err; | |
147 | ||
b7e2ecef | 148 | raw_data = per_cpu_ptr(trace_buf, smp_processor_id()); |
430ad5a6 XG |
149 | |
150 | /* zero the dead bytes from align to not leak stack to user */ | |
eb1e7961 | 151 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
430ad5a6 XG |
152 | |
153 | entry = (struct trace_entry *)raw_data; | |
b7e2ecef | 154 | tracing_generic_entry_update(entry, regs->flags, pc); |
430ad5a6 XG |
155 | entry->type = type; |
156 | ||
157 | return raw_data; | |
158 | err: | |
159 | perf_swevent_put_recursion_context(*rctxp); | |
160 | err_recursion: | |
430ad5a6 XG |
161 | return NULL; |
162 | } | |
97d5a220 | 163 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |