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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 | 35 | return 0; |
1c024eca PZ |
36 | |
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)); | |
43 | ||
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 | ||
1c024eca PZ |
59 | ret = tp_event->perf_event_enable(tp_event); |
60 | if (ret) | |
61 | goto fail; | |
20ab4425 | 62 | |
1c024eca PZ |
63 | total_ref_count++; |
64 | return 0; | |
65 | ||
66 | fail: | |
97d5a220 | 67 | if (!total_ref_count) { |
b7e2ecef PZ |
68 | int i; |
69 | ||
70 | for (i = 0; i < 4; i++) { | |
71 | free_percpu(perf_trace_buf[i]); | |
72 | perf_trace_buf[i] = NULL; | |
73 | } | |
fe8e5b5a | 74 | } |
1c024eca PZ |
75 | |
76 | if (!--tp_event->perf_refcount) { | |
77 | free_percpu(tp_event->perf_events); | |
78 | tp_event->perf_events = NULL; | |
79 | } | |
20ab4425 FW |
80 | |
81 | return ret; | |
e5e25cf4 FW |
82 | } |
83 | ||
1c024eca | 84 | int perf_trace_init(struct perf_event *p_event) |
ac199db0 | 85 | { |
1c024eca PZ |
86 | struct ftrace_event_call *tp_event; |
87 | int event_id = p_event->attr.config; | |
20c8928a | 88 | int ret = -EINVAL; |
ac199db0 | 89 | |
20c8928a | 90 | mutex_lock(&event_mutex); |
1c024eca PZ |
91 | list_for_each_entry(tp_event, &ftrace_events, list) { |
92 | if (tp_event->id == event_id && tp_event->perf_event_enable && | |
93 | try_module_get(tp_event->mod)) { | |
94 | ret = perf_trace_event_init(tp_event, p_event); | |
20c8928a LZ |
95 | break; |
96 | } | |
ac199db0 | 97 | } |
20c8928a | 98 | mutex_unlock(&event_mutex); |
ac199db0 | 99 | |
20c8928a | 100 | return ret; |
ac199db0 PZ |
101 | } |
102 | ||
1c024eca | 103 | int perf_trace_enable(struct perf_event *p_event) |
e5e25cf4 | 104 | { |
1c024eca PZ |
105 | struct ftrace_event_call *tp_event = p_event->tp_event; |
106 | struct hlist_head *list; | |
e5e25cf4 | 107 | |
1c024eca PZ |
108 | list = tp_event->perf_events; |
109 | if (WARN_ON_ONCE(!list)) | |
110 | return -EINVAL; | |
20ab4425 | 111 | |
1c024eca PZ |
112 | list = per_cpu_ptr(list, smp_processor_id()); |
113 | hlist_add_head_rcu(&p_event->hlist_entry, list); | |
20ab4425 | 114 | |
1c024eca PZ |
115 | return 0; |
116 | } | |
20ab4425 | 117 | |
1c024eca PZ |
118 | void perf_trace_disable(struct perf_event *p_event) |
119 | { | |
120 | hlist_del_rcu(&p_event->hlist_entry); | |
e5e25cf4 FW |
121 | } |
122 | ||
1c024eca | 123 | void perf_trace_destroy(struct perf_event *p_event) |
ac199db0 | 124 | { |
1c024eca PZ |
125 | struct ftrace_event_call *tp_event = p_event->tp_event; |
126 | int i; | |
ac199db0 | 127 | |
1c024eca PZ |
128 | if (--tp_event->perf_refcount > 0) |
129 | return; | |
130 | ||
131 | tp_event->perf_event_disable(tp_event); | |
132 | ||
133 | free_percpu(tp_event->perf_events); | |
134 | tp_event->perf_events = NULL; | |
135 | ||
136 | if (!--total_ref_count) { | |
137 | for (i = 0; i < 4; i++) { | |
138 | free_percpu(perf_trace_buf[i]); | |
139 | perf_trace_buf[i] = NULL; | |
20c8928a | 140 | } |
ac199db0 PZ |
141 | } |
142 | } | |
430ad5a6 | 143 | |
97d5a220 | 144 | __kprobes void *perf_trace_buf_prepare(int size, unsigned short type, |
b7e2ecef | 145 | struct pt_regs *regs, int *rctxp) |
430ad5a6 XG |
146 | { |
147 | struct trace_entry *entry; | |
1c024eca | 148 | char *raw_data; |
b7e2ecef | 149 | int pc; |
430ad5a6 | 150 | |
eb1e7961 FW |
151 | BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); |
152 | ||
430ad5a6 XG |
153 | pc = preempt_count(); |
154 | ||
430ad5a6 XG |
155 | *rctxp = perf_swevent_get_recursion_context(); |
156 | if (*rctxp < 0) | |
1c024eca | 157 | return NULL; |
430ad5a6 | 158 | |
1c024eca | 159 | raw_data = per_cpu_ptr(perf_trace_buf[*rctxp], smp_processor_id()); |
430ad5a6 XG |
160 | |
161 | /* zero the dead bytes from align to not leak stack to user */ | |
eb1e7961 | 162 | memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64)); |
430ad5a6 XG |
163 | |
164 | entry = (struct trace_entry *)raw_data; | |
b7e2ecef | 165 | tracing_generic_entry_update(entry, regs->flags, pc); |
430ad5a6 XG |
166 | entry->type = type; |
167 | ||
168 | return raw_data; | |
430ad5a6 | 169 | } |
97d5a220 | 170 | EXPORT_SYMBOL_GPL(perf_trace_buf_prepare); |