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
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
|
/**
* @file cpu_buffer.c
*
* @remark Copyright 2002-2009 OProfile authors
* @remark Read the file COPYING
*
* @author John Levon <levon@movementarian.org>
* @author Barry Kasindorf <barry.kasindorf@amd.com>
* @author Robert Richter <robert.richter@amd.com>
*
* Each CPU has a local buffer that stores PC value/event
* pairs. We also log context switches when we notice them.
* Eventually each CPU's buffer is processed into the global
* event buffer by sync_buffer().
*
* We use a local buffer for two reasons: an NMI or similar
* interrupt cannot synchronise, and high sampling rates
* would lead to catastrophic global synchronisation if
* a global buffer was used.
*/
#include <linux/sched.h>
#include <linux/oprofile.h>
#include <linux/errno.h>
#include "event_buffer.h"
#include "cpu_buffer.h"
#include "buffer_sync.h"
#include "oprof.h"
#define OP_BUFFER_FLAGS 0
static struct ring_buffer *op_ring_buffer;
DEFINE_PER_CPU(struct oprofile_cpu_buffer, op_cpu_buffer);
static void wq_sync_buffer(struct work_struct *work);
#define DEFAULT_TIMER_EXPIRE (HZ / 10)
static int work_enabled;
unsigned long oprofile_get_cpu_buffer_size(void)
{
return oprofile_cpu_buffer_size;
}
void oprofile_cpu_buffer_inc_smpl_lost(void)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);
cpu_buf->sample_lost_overflow++;
}
void free_cpu_buffers(void)
{
if (op_ring_buffer)
ring_buffer_free(op_ring_buffer);
op_ring_buffer = NULL;
}
#define RB_EVENT_HDR_SIZE 4
int alloc_cpu_buffers(void)
{
int i;
unsigned long buffer_size = oprofile_cpu_buffer_size;
unsigned long byte_size = buffer_size * (sizeof(struct op_sample) +
RB_EVENT_HDR_SIZE);
op_ring_buffer = ring_buffer_alloc(byte_size, OP_BUFFER_FLAGS);
if (!op_ring_buffer)
goto fail;
for_each_possible_cpu(i) {
struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i);
b->last_task = NULL;
b->last_is_kernel = -1;
b->tracing = 0;
b->buffer_size = buffer_size;
b->sample_received = 0;
b->sample_lost_overflow = 0;
b->backtrace_aborted = 0;
b->sample_invalid_eip = 0;
b->cpu = i;
INIT_DELAYED_WORK(&b->work, wq_sync_buffer);
}
return 0;
fail:
free_cpu_buffers();
return -ENOMEM;
}
void start_cpu_work(void)
{
int i;
work_enabled = 1;
for_each_online_cpu(i) {
struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i);
/*
* Spread the work by 1 jiffy per cpu so they dont all
* fire at once.
*/
schedule_delayed_work_on(i, &b->work, DEFAULT_TIMER_EXPIRE + i);
}
}
void end_cpu_work(void)
{
int i;
work_enabled = 0;
for_each_online_cpu(i) {
struct oprofile_cpu_buffer *b = &per_cpu(op_cpu_buffer, i);
cancel_delayed_work(&b->work);
}
flush_scheduled_work();
}
/*
* This function prepares the cpu buffer to write a sample.
*
* Struct op_entry is used during operations on the ring buffer while
* struct op_sample contains the data that is stored in the ring
* buffer. Struct entry can be uninitialized. The function reserves a
* data array that is specified by size. Use
* op_cpu_buffer_write_commit() after preparing the sample. In case of
* errors a null pointer is returned, otherwise the pointer to the
* sample.
*
*/
struct op_sample
*op_cpu_buffer_write_reserve(struct op_entry *entry, unsigned long size)
{
entry->event = ring_buffer_lock_reserve
(op_ring_buffer, sizeof(struct op_sample) +
size * sizeof(entry->sample->data[0]));
if (!entry->event)
return NULL;
entry->sample = ring_buffer_event_data(entry->event);
entry->size = size;
entry->data = entry->sample->data;
return entry->sample;
}
int op_cpu_buffer_write_commit(struct op_entry *entry)
{
return ring_buffer_unlock_commit(op_ring_buffer, entry->event);
}
struct op_sample *op_cpu_buffer_read_entry(struct op_entry *entry, int cpu)
{
struct ring_buffer_event *e;
e = ring_buffer_consume(op_ring_buffer, cpu, NULL, NULL);
if (!e)
return NULL;
entry->event = e;
entry->sample = ring_buffer_event_data(e);
entry->size = (ring_buffer_event_length(e) - sizeof(struct op_sample))
/ sizeof(entry->sample->data[0]);
entry->data = entry->sample->data;
return entry->sample;
}
unsigned long op_cpu_buffer_entries(int cpu)
{
return ring_buffer_entries_cpu(op_ring_buffer, cpu);
}
static int
op_add_code(struct oprofile_cpu_buffer *cpu_buf, unsigned long backtrace,
int is_kernel, struct task_struct *task)
{
struct op_entry entry;
struct op_sample *sample;
unsigned long flags;
int size;
flags = 0;
if (backtrace)
flags |= TRACE_BEGIN;
/* notice a switch from user->kernel or vice versa */
is_kernel = !!is_kernel;
if (cpu_buf->last_is_kernel != is_kernel) {
cpu_buf->last_is_kernel = is_kernel;
flags |= KERNEL_CTX_SWITCH;
if (is_kernel)
flags |= IS_KERNEL;
}
/* notice a task switch */
if (cpu_buf->last_task != task) {
cpu_buf->last_task = task;
flags |= USER_CTX_SWITCH;
}
if (!flags)
/* nothing to do */
return 0;
if (flags & USER_CTX_SWITCH)
size = 1;
else
size = 0;
sample = op_cpu_buffer_write_reserve(&entry, size);
if (!sample)
return -ENOMEM;
sample->eip = ESCAPE_CODE;
sample->event = flags;
if (size)
op_cpu_buffer_add_data(&entry, (unsigned long)task);
op_cpu_buffer_write_commit(&entry);
return 0;
}
static inline int
op_add_sample(struct oprofile_cpu_buffer *cpu_buf,
unsigned long pc, unsigned long event)
{
struct op_entry entry;
struct op_sample *sample;
sample = op_cpu_buffer_write_reserve(&entry, 0);
if (!sample)
return -ENOMEM;
sample->eip = pc;
sample->event = event;
return op_cpu_buffer_write_commit(&entry);
}
/*
* This must be safe from any context.
*
* is_kernel is needed because on some architectures you cannot
* tell if you are in kernel or user space simply by looking at
* pc. We tag this in the buffer by generating kernel enter/exit
* events whenever is_kernel changes
*/
static int
log_sample(struct oprofile_cpu_buffer *cpu_buf, unsigned long pc,
unsigned long backtrace, int is_kernel, unsigned long event)
{
cpu_buf->sample_received++;
if (pc == ESCAPE_CODE) {
cpu_buf->sample_invalid_eip++;
return 0;
}
if (op_add_code(cpu_buf, backtrace, is_kernel, current))
goto fail;
if (op_add_sample(cpu_buf, pc, event))
goto fail;
return 1;
fail:
cpu_buf->sample_lost_overflow++;
return 0;
}
static inline void oprofile_begin_trace(struct oprofile_cpu_buffer *cpu_buf)
{
cpu_buf->tracing = 1;
}
static inline void oprofile_end_trace(struct oprofile_cpu_buffer *cpu_buf)
{
cpu_buf->tracing = 0;
}
static inline void
__oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
unsigned long event, int is_kernel)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);
unsigned long backtrace = oprofile_backtrace_depth;
/*
* if log_sample() fail we can't backtrace since we lost the
* source of this event
*/
if (!log_sample(cpu_buf, pc, backtrace, is_kernel, event))
/* failed */
return;
if (!backtrace)
return;
oprofile_begin_trace(cpu_buf);
oprofile_ops.backtrace(regs, backtrace);
oprofile_end_trace(cpu_buf);
}
void oprofile_add_ext_sample(unsigned long pc, struct pt_regs * const regs,
unsigned long event, int is_kernel)
{
__oprofile_add_ext_sample(pc, regs, event, is_kernel);
}
void oprofile_add_sample(struct pt_regs * const regs, unsigned long event)
{
int is_kernel = !user_mode(regs);
unsigned long pc = profile_pc(regs);
__oprofile_add_ext_sample(pc, regs, event, is_kernel);
}
/*
* Add samples with data to the ring buffer.
*
* Use oprofile_add_data(&entry, val) to add data and
* oprofile_write_commit(&entry) to commit the sample.
*/
void
oprofile_write_reserve(struct op_entry *entry, struct pt_regs * const regs,
unsigned long pc, int code, int size)
{
struct op_sample *sample;
int is_kernel = !user_mode(regs);
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);
cpu_buf->sample_received++;
/* no backtraces for samples with data */
if (op_add_code(cpu_buf, 0, is_kernel, current))
goto fail;
sample = op_cpu_buffer_write_reserve(entry, size + 2);
if (!sample)
goto fail;
sample->eip = ESCAPE_CODE;
sample->event = 0; /* no flags */
op_cpu_buffer_add_data(entry, code);
op_cpu_buffer_add_data(entry, pc);
return;
fail:
entry->event = NULL;
cpu_buf->sample_lost_overflow++;
}
int oprofile_add_data(struct op_entry *entry, unsigned long val)
{
if (!entry->event)
return 0;
return op_cpu_buffer_add_data(entry, val);
}
int oprofile_add_data64(struct op_entry *entry, u64 val)
{
if (!entry->event)
return 0;
if (op_cpu_buffer_get_size(entry) < 2)
/*
* the function returns 0 to indicate a too small
* buffer, even if there is some space left
*/
return 0;
if (!op_cpu_buffer_add_data(entry, (u32)val))
return 0;
return op_cpu_buffer_add_data(entry, (u32)(val >> 32));
}
int oprofile_write_commit(struct op_entry *entry)
{
if (!entry->event)
return -EINVAL;
return op_cpu_buffer_write_commit(entry);
}
void oprofile_add_pc(unsigned long pc, int is_kernel, unsigned long event)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);
log_sample(cpu_buf, pc, 0, is_kernel, event);
}
void oprofile_add_trace(unsigned long pc)
{
struct oprofile_cpu_buffer *cpu_buf = &__get_cpu_var(op_cpu_buffer);
if (!cpu_buf->tracing)
return;
/*
* broken frame can give an eip with the same value as an
* escape code, abort the trace if we get it
*/
if (pc == ESCAPE_CODE)
goto fail;
if (op_add_sample(cpu_buf, pc, 0))
goto fail;
return;
fail:
cpu_buf->tracing = 0;
cpu_buf->backtrace_aborted++;
return;
}
/*
* This serves to avoid cpu buffer overflow, and makes sure
* the task mortuary progresses
*
* By using schedule_delayed_work_on and then schedule_delayed_work
* we guarantee this will stay on the correct cpu
*/
static void wq_sync_buffer(struct work_struct *work)
{
struct oprofile_cpu_buffer *b =
container_of(work, struct oprofile_cpu_buffer, work.work);
if (b->cpu != smp_processor_id()) {
printk(KERN_DEBUG "WQ on CPU%d, prefer CPU%d\n",
smp_processor_id(), b->cpu);
if (!cpu_online(b->cpu)) {
cancel_delayed_work(&b->work);
return;
}
}
sync_buffer(b->cpu);
/* don't re-add the work if we're shutting down */
if (work_enabled)
schedule_delayed_work(&b->work, DEFAULT_TIMER_EXPIRE);
}
|