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Commit | Line | Data |
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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 | |
1c024eca PZ |
26 | static int perf_trace_event_init(struct ftrace_event_call *tp_event, |
27 | struct perf_event *p_event) | |
e5e25cf4 | 28 | { |
1c024eca | 29 | struct hlist_head *list; |
20ab4425 | 30 | int ret = -ENOMEM; |
1c024eca | 31 | int cpu; |
20ab4425 | 32 | |
1c024eca PZ |
33 | p_event->tp_event = tp_event; |
34 | if (tp_event->perf_refcount++ > 0) | |
e5e25cf4 FW |
35 | return 0; |
36 | ||
1c024eca PZ |
37 | list = alloc_percpu(struct hlist_head); |
38 | if (!list) | |
39 | goto fail; | |
40 | ||
41 | for_each_possible_cpu(cpu) | |
42 | INIT_HLIST_HEAD(per_cpu_ptr(list, cpu)); | |
20ab4425 | 43 | |
1c024eca | 44 | tp_event->perf_events = list; |
e5e25cf4 | 45 | |
97d5a220 | 46 | if (!total_ref_count) { |
b7e2ecef PZ |
47 | char *buf; |
48 | int i; | |
20ab4425 | 49 | |
b7e2ecef PZ |
50 | for (i = 0; i < 4; i++) { |
51 | buf = (char *)alloc_percpu(perf_trace_t); | |
52 | if (!buf) | |
1c024eca | 53 | goto fail; |
20ab4425 | 54 | |
1c024eca | 55 | perf_trace_buf[i] = buf; |
b7e2ecef | 56 | } |
20ab4425 FW |
57 | } |
58 | ||
ff5f149b SR |
59 | if (tp_event->class->reg) |
60 | ret = tp_event->class->reg(tp_event, TRACE_REG_PERF_REGISTER); | |
2239291a | 61 | else |
ff5f149b SR |
62 | ret = tracepoint_probe_register(tp_event->name, |
63 | tp_event->class->perf_probe, | |
64 | tp_event); | |
65 | ||
1c024eca PZ |
66 | if (ret) |
67 | goto fail; | |
20ab4425 | 68 | |
1c024eca PZ |
69 | total_ref_count++; |
70 | return 0; | |
71 | ||
72 | fail: | |
97d5a220 | 73 | if (!total_ref_count) { |
b7e2ecef PZ |
74 | int i; |
75 | ||
76 | for (i = 0; i < 4; i++) { | |
77 | free_percpu(perf_trace_buf[i]); | |
78 | perf_trace_buf[i] = NULL; | |
79 | } | |
fe8e5b5a | 80 | } |
1c024eca PZ |
81 | |
82 | if (!--tp_event->perf_refcount) { | |
83 | free_percpu(tp_event->perf_events); | |
84 | tp_event->perf_events = NULL; | |
fe8e5b5a | 85 | } |
20ab4425 FW |
86 | |
87 | return ret; | |
e5e25cf4 FW |
88 | } |
89 | ||
1c024eca | 90 | int perf_trace_init(struct perf_event *p_event) |
ac199db0 | 91 | { |
1c024eca PZ |
92 | struct ftrace_event_call *tp_event; |
93 | int event_id = p_event->attr.config; | |
20c8928a | 94 | int ret = -EINVAL; |
ac199db0 | 95 | |
20c8928a | 96 | mutex_lock(&event_mutex); |
1c024eca | 97 | list_for_each_entry(tp_event, &ftrace_events, list) { |
ff5f149b | 98 | if (tp_event->event.type == event_id && |
a8fb2608 SR |
99 | tp_event->class && |
100 | (tp_event->class->perf_probe || | |
101 | tp_event->class->reg) && | |
1c024eca PZ |
102 | try_module_get(tp_event->mod)) { |
103 | ret = perf_trace_event_init(tp_event, p_event); | |
20c8928a LZ |
104 | break; |
105 | } | |
ac199db0 | 106 | } |
20c8928a | 107 | mutex_unlock(&event_mutex); |
ac199db0 | 108 | |
20c8928a | 109 | return ret; |
ac199db0 PZ |
110 | } |
111 | ||
1c024eca | 112 | int perf_trace_enable(struct perf_event *p_event) |
e5e25cf4 | 113 | { |
1c024eca PZ |
114 | struct ftrace_event_call *tp_event = p_event->tp_event; |
115 | struct hlist_head *list; | |
20ab4425 | 116 | |
1c024eca PZ |
117 | list = tp_event->perf_events; |
118 | if (WARN_ON_ONCE(!list)) | |
119 | return -EINVAL; | |
20ab4425 | 120 | |
3771f077 | 121 | list = this_cpu_ptr(list); |
1c024eca | 122 | hlist_add_head_rcu(&p_event->hlist_entry, list); |
20ab4425 | 123 | |
1c024eca PZ |
124 | return 0; |
125 | } | |
20ab4425 | 126 | |
1c024eca PZ |
127 | void perf_trace_disable(struct perf_event *p_event) |
128 | { | |
129 | hlist_del_rcu(&p_event->hlist_entry); | |
e5e25cf4 FW |
130 | } |
131 | ||
1c024eca | 132 | void perf_trace_destroy(struct perf_event *p_event) |
ac199db0 | 133 | { |
1c024eca PZ |
134 | struct ftrace_event_call *tp_event = p_event->tp_event; |
135 | int i; | |
ac199db0 | 136 | |
2e97942f | 137 | mutex_lock(&event_mutex); |
1c024eca | 138 | if (--tp_event->perf_refcount > 0) |
2e97942f | 139 | goto out; |
1c024eca | 140 | |
ff5f149b SR |
141 | if (tp_event->class->reg) |
142 | tp_event->class->reg(tp_event, TRACE_REG_PERF_UNREGISTER); | |
143 | else | |
144 | tracepoint_probe_unregister(tp_event->name, | |
145 | tp_event->class->perf_probe, | |
146 | tp_event); | |
1c024eca | 147 | |
3771f077 PZ |
148 | /* |
149 | * Ensure our callback won't be called anymore. See | |
150 | * tracepoint_probe_unregister() and __DO_TRACE(). | |
151 | */ | |
152 | synchronize_sched(); | |
153 | ||
1c024eca PZ |
154 | free_percpu(tp_event->perf_events); |
155 | tp_event->perf_events = NULL; | |
156 | ||
157 | if (!--total_ref_count) { | |
158 | for (i = 0; i < 4; i++) { | |
159 | free_percpu(perf_trace_buf[i]); | |
160 | perf_trace_buf[i] = NULL; | |
20c8928a | 161 | } |
ac199db0 | 162 | } |
2e97942f PZ |
163 | out: |
164 | mutex_unlock(&event_mutex); | |
ac199db0 | 165 | } |
430ad5a6 | 166 | |
97d5a220 | 167 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
b7e2ecef | 168 | struct pt_regs *regs, int *rctxp) |
430ad5a6 XG |
169 | { |
170 | struct trace_entry *entry; | |
87f44bbc | 171 | unsigned long flags; |
1c024eca | 172 | char *raw_data; |
b7e2ecef | 173 | int pc; |
430ad5a6 | 174 | |
eb1e7961 FW |
175 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
176 | ||
430ad5a6 XG |
177 | pc = preempt_count(); |
178 | ||
430ad5a6 XG |
179 | *rctxp = perf_swevent_get_recursion_context(); |
180 | if (*rctxp < 0) | |
1c024eca | 181 | return NULL; |
430ad5a6 | 182 | |
3771f077 | 183 | raw_data = this_cpu_ptr(perf_trace_buf[*rctxp]); |
430ad5a6 XG |
184 | |
185 | /* zero the dead bytes from align to not leak stack to user */ | |
eb1e7961 | 186 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
430ad5a6 XG |
187 | |
188 | entry = (struct trace_entry *)raw_data; | |
87f44bbc PZ |
189 | local_save_flags(flags); |
190 | tracing_generic_entry_update(entry, flags, pc); | |
430ad5a6 XG |
191 | entry->type = type; |
192 | ||
193 | return raw_data; | |
430ad5a6 | 194 | } |
97d5a220 | 195 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |