1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
/*
* trace event based perf event profiling/tracing
*
* Copyright (C) 2009 Red Hat Inc, Peter Zijlstra <pzijlstr@redhat.com>
* Copyright (C) 2009-2010 Frederic Weisbecker <fweisbec@gmail.com>
*/
#include <linux/module.h>
#include <linux/kprobes.h>
#include "trace.h"
DEFINE_PER_CPU(struct pt_regs, perf_trace_regs);
EXPORT_PER_CPU_SYMBOL_GPL(perf_trace_regs);
EXPORT_SYMBOL_GPL(perf_arch_fetch_caller_regs);
static char *perf_trace_buf;
static char *perf_trace_buf_nmi;
/*
* Force it to be aligned to unsigned long to avoid misaligned accesses
* suprises
*/
typedef typeof(unsigned long [PERF_MAX_TRACE_SIZE / sizeof(unsigned long)])
perf_trace_t;
/* Count the events in use (per event id, not per instance) */
static int total_ref_count;
static int perf_trace_event_enable(struct ftrace_event_call *event)
{
char *buf;
int ret = -ENOMEM;
if (event->perf_refcount++ > 0)
return 0;
if (!total_ref_count) {
buf = (char *)alloc_percpu(perf_trace_t);
if (!buf)
goto fail_buf;
rcu_assign_pointer(perf_trace_buf, buf);
buf = (char *)alloc_percpu(perf_trace_t);
if (!buf)
goto fail_buf_nmi;
rcu_assign_pointer(perf_trace_buf_nmi, buf);
}
if (event->class->reg)
ret = event->class->reg(event, TRACE_REG_PERF_REGISTER);
else
ret = tracepoint_probe_register(event->name,
event->class->perf_probe,
event);
if (!ret) {
total_ref_count++;
return 0;
}
fail_buf_nmi:
if (!total_ref_count) {
free_percpu(perf_trace_buf_nmi);
free_percpu(perf_trace_buf);
perf_trace_buf_nmi = NULL;
perf_trace_buf = NULL;
}
fail_buf:
event->perf_refcount--;
return ret;
}
int perf_trace_enable(int event_id)
{
struct ftrace_event_call *event;
int ret = -EINVAL;
mutex_lock(&event_mutex);
list_for_each_entry(event, &ftrace_events, list) {
if (event->event.type == event_id &&
event->class && event->class->perf_probe &&
try_module_get(event->mod)) {
ret = perf_trace_event_enable(event);
break;
}
}
mutex_unlock(&event_mutex);
return ret;
}
static void perf_trace_event_disable(struct ftrace_event_call *event)
{
char *buf, *nmi_buf;
if (--event->perf_refcount > 0)
return;
if (event->class->reg)
event->class->reg(event, TRACE_REG_PERF_UNREGISTER);
else
tracepoint_probe_unregister(event->name, event->class->perf_probe, event);
if (!--total_ref_count) {
buf = perf_trace_buf;
rcu_assign_pointer(perf_trace_buf, NULL);
nmi_buf = perf_trace_buf_nmi;
rcu_assign_pointer(perf_trace_buf_nmi, NULL);
/*
* Ensure every events in profiling have finished before
* releasing the buffers
*/
synchronize_sched();
free_percpu(buf);
free_percpu(nmi_buf);
}
}
void perf_trace_disable(int event_id)
{
struct ftrace_event_call *event;
mutex_lock(&event_mutex);
list_for_each_entry(event, &ftrace_events, list) {
if (event->event.type == event_id) {
perf_trace_event_disable(event);
module_put(event->mod);
break;
}
}
mutex_unlock(&event_mutex);
}
__kprobes void *perf_trace_buf_prepare(int size, unsigned short type,
int *rctxp, unsigned long *irq_flags)
{
struct trace_entry *entry;
char *trace_buf, *raw_data;
int pc, cpu;
BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long));
pc = preempt_count();
/* Protect the per cpu buffer, begin the rcu read side */
local_irq_save(*irq_flags);
*rctxp = perf_swevent_get_recursion_context();
if (*rctxp < 0)
goto err_recursion;
cpu = smp_processor_id();
if (in_nmi())
trace_buf = rcu_dereference_sched(perf_trace_buf_nmi);
else
trace_buf = rcu_dereference_sched(perf_trace_buf);
if (!trace_buf)
goto err;
raw_data = per_cpu_ptr(trace_buf, cpu);
/* zero the dead bytes from align to not leak stack to user */
memset(&raw_data[size - sizeof(u64)], 0, sizeof(u64));
entry = (struct trace_entry *)raw_data;
tracing_generic_entry_update(entry, *irq_flags, pc);
entry->type = type;
return raw_data;
err:
perf_swevent_put_recursion_context(*rctxp);
err_recursion:
local_irq_restore(*irq_flags);
return NULL;
}
EXPORT_SYMBOL_GPL(perf_trace_buf_prepare);
|
