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7c97f91e MM |
1 | /* Linux-dependent part of branch trace support for GDB, and GDBserver. |
2 | ||
ecd75fc8 | 3 | Copyright (C) 2013-2014 Free Software Foundation, Inc. |
7c97f91e MM |
4 | |
5 | Contributed by Intel Corp. <markus.t.metzger@intel.com> | |
6 | ||
7 | This file is part of GDB. | |
8 | ||
9 | This program is free software; you can redistribute it and/or modify | |
10 | it under the terms of the GNU General Public License as published by | |
11 | the Free Software Foundation; either version 3 of the License, or | |
12 | (at your option) any later version. | |
13 | ||
14 | This program is distributed in the hope that it will be useful, | |
15 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | GNU General Public License for more details. | |
18 | ||
19 | You should have received a copy of the GNU General Public License | |
20 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
21 | ||
22 | #ifdef GDBSERVER | |
23 | #include "server.h" | |
24 | #else | |
25 | #include "defs.h" | |
26 | #endif | |
27 | ||
28 | #include "linux-btrace.h" | |
29 | #include "common-utils.h" | |
30 | #include "gdb_assert.h" | |
31 | #include "regcache.h" | |
32 | #include "gdbthread.h" | |
be8b1ea6 | 33 | #include "gdb_wait.h" |
4d157a3d | 34 | #include "i386-cpuid.h" |
7c97f91e | 35 | |
5b4e221c MF |
36 | #ifdef HAVE_SYS_SYSCALL_H |
37 | #include <sys/syscall.h> | |
38 | #endif | |
39 | ||
40 | #if HAVE_LINUX_PERF_EVENT_H && defined(SYS_perf_event_open) | |
7c97f91e MM |
41 | |
42 | #include <errno.h> | |
43 | #include <string.h> | |
44 | #include <stdint.h> | |
45 | #include <unistd.h> | |
7c97f91e MM |
46 | #include <sys/mman.h> |
47 | #include <sys/user.h> | |
a950d57c MM |
48 | #include <sys/ptrace.h> |
49 | #include <sys/types.h> | |
a950d57c | 50 | #include <signal.h> |
7c97f91e MM |
51 | |
52 | /* A branch trace record in perf_event. */ | |
53 | struct perf_event_bts | |
54 | { | |
55 | /* The linear address of the branch source. */ | |
56 | uint64_t from; | |
57 | ||
58 | /* The linear address of the branch destination. */ | |
59 | uint64_t to; | |
60 | }; | |
61 | ||
62 | /* A perf_event branch trace sample. */ | |
63 | struct perf_event_sample | |
64 | { | |
65 | /* The perf_event sample header. */ | |
66 | struct perf_event_header header; | |
67 | ||
68 | /* The perf_event branch tracing payload. */ | |
69 | struct perf_event_bts bts; | |
70 | }; | |
71 | ||
72 | /* Get the perf_event header. */ | |
73 | ||
74 | static inline volatile struct perf_event_mmap_page * | |
75 | perf_event_header (struct btrace_target_info* tinfo) | |
76 | { | |
77 | return tinfo->buffer; | |
78 | } | |
79 | ||
80 | /* Get the size of the perf_event mmap buffer. */ | |
81 | ||
82 | static inline size_t | |
83 | perf_event_mmap_size (const struct btrace_target_info *tinfo) | |
84 | { | |
85 | /* The branch trace buffer is preceded by a configuration page. */ | |
86 | return (tinfo->size + 1) * PAGE_SIZE; | |
87 | } | |
88 | ||
89 | /* Get the size of the perf_event buffer. */ | |
90 | ||
91 | static inline size_t | |
92 | perf_event_buffer_size (struct btrace_target_info* tinfo) | |
93 | { | |
94 | return tinfo->size * PAGE_SIZE; | |
95 | } | |
96 | ||
97 | /* Get the start address of the perf_event buffer. */ | |
98 | ||
99 | static inline const uint8_t * | |
100 | perf_event_buffer_begin (struct btrace_target_info* tinfo) | |
101 | { | |
102 | return ((const uint8_t *) tinfo->buffer) + PAGE_SIZE; | |
103 | } | |
104 | ||
105 | /* Get the end address of the perf_event buffer. */ | |
106 | ||
107 | static inline const uint8_t * | |
108 | perf_event_buffer_end (struct btrace_target_info* tinfo) | |
109 | { | |
110 | return perf_event_buffer_begin (tinfo) + perf_event_buffer_size (tinfo); | |
111 | } | |
112 | ||
113 | /* Check whether an address is in the kernel. */ | |
114 | ||
115 | static inline int | |
116 | perf_event_is_kernel_addr (const struct btrace_target_info *tinfo, | |
117 | uint64_t addr) | |
118 | { | |
119 | uint64_t mask; | |
120 | ||
121 | /* If we don't know the size of a pointer, we can't check. Let's assume it's | |
122 | not a kernel address in this case. */ | |
123 | if (tinfo->ptr_bits == 0) | |
124 | return 0; | |
125 | ||
126 | /* A bit mask for the most significant bit in an address. */ | |
127 | mask = (uint64_t) 1 << (tinfo->ptr_bits - 1); | |
128 | ||
129 | /* Check whether the most significant bit in the address is set. */ | |
130 | return (addr & mask) != 0; | |
131 | } | |
132 | ||
133 | /* Check whether a perf event record should be skipped. */ | |
134 | ||
135 | static inline int | |
136 | perf_event_skip_record (const struct btrace_target_info *tinfo, | |
137 | const struct perf_event_bts *bts) | |
138 | { | |
139 | /* The hardware may report branches from kernel into user space. Branches | |
140 | from user into kernel space will be suppressed. We filter the former to | |
141 | provide a consistent branch trace excluding kernel. */ | |
142 | return perf_event_is_kernel_addr (tinfo, bts->from); | |
143 | } | |
144 | ||
145 | /* Perform a few consistency checks on a perf event sample record. This is | |
146 | meant to catch cases when we get out of sync with the perf event stream. */ | |
147 | ||
148 | static inline int | |
149 | perf_event_sample_ok (const struct perf_event_sample *sample) | |
150 | { | |
151 | if (sample->header.type != PERF_RECORD_SAMPLE) | |
152 | return 0; | |
153 | ||
154 | if (sample->header.size != sizeof (*sample)) | |
155 | return 0; | |
156 | ||
157 | return 1; | |
158 | } | |
159 | ||
160 | /* Branch trace is collected in a circular buffer [begin; end) as pairs of from | |
161 | and to addresses (plus a header). | |
162 | ||
163 | Start points into that buffer at the next sample position. | |
164 | We read the collected samples backwards from start. | |
165 | ||
166 | While reading the samples, we convert the information into a list of blocks. | |
167 | For two adjacent samples s1 and s2, we form a block b such that b.begin = | |
168 | s1.to and b.end = s2.from. | |
169 | ||
170 | In case the buffer overflows during sampling, one sample may have its lower | |
171 | part at the end and its upper part at the beginning of the buffer. */ | |
172 | ||
173 | static VEC (btrace_block_s) * | |
174 | perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin, | |
969c39fb | 175 | const uint8_t *end, const uint8_t *start, size_t size) |
7c97f91e MM |
176 | { |
177 | VEC (btrace_block_s) *btrace = NULL; | |
178 | struct perf_event_sample sample; | |
969c39fb | 179 | size_t read = 0; |
7c97f91e MM |
180 | struct btrace_block block = { 0, 0 }; |
181 | struct regcache *regcache; | |
182 | ||
183 | gdb_assert (begin <= start); | |
184 | gdb_assert (start <= end); | |
185 | ||
186 | /* The first block ends at the current pc. */ | |
187 | #ifdef GDBSERVER | |
188 | regcache = get_thread_regcache (find_thread_ptid (tinfo->ptid), 1); | |
189 | #else | |
190 | regcache = get_thread_regcache (tinfo->ptid); | |
191 | #endif | |
192 | block.end = regcache_read_pc (regcache); | |
193 | ||
194 | /* The buffer may contain a partial record as its last entry (i.e. when the | |
195 | buffer size is not a multiple of the sample size). */ | |
196 | read = sizeof (sample) - 1; | |
197 | ||
198 | for (; read < size; read += sizeof (sample)) | |
199 | { | |
200 | const struct perf_event_sample *psample; | |
201 | ||
202 | /* Find the next perf_event sample in a backwards traversal. */ | |
203 | start -= sizeof (sample); | |
204 | ||
205 | /* If we're still inside the buffer, we're done. */ | |
206 | if (begin <= start) | |
207 | psample = (const struct perf_event_sample *) start; | |
208 | else | |
209 | { | |
210 | int missing; | |
211 | ||
212 | /* We're to the left of the ring buffer, we will wrap around and | |
213 | reappear at the very right of the ring buffer. */ | |
214 | ||
215 | missing = (begin - start); | |
216 | start = (end - missing); | |
217 | ||
218 | /* If the entire sample is missing, we're done. */ | |
219 | if (missing == sizeof (sample)) | |
220 | psample = (const struct perf_event_sample *) start; | |
221 | else | |
222 | { | |
223 | uint8_t *stack; | |
224 | ||
225 | /* The sample wrapped around. The lower part is at the end and | |
226 | the upper part is at the beginning of the buffer. */ | |
227 | stack = (uint8_t *) &sample; | |
228 | ||
229 | /* Copy the two parts so we have a contiguous sample. */ | |
230 | memcpy (stack, start, missing); | |
231 | memcpy (stack + missing, begin, sizeof (sample) - missing); | |
232 | ||
233 | psample = &sample; | |
234 | } | |
235 | } | |
236 | ||
237 | if (!perf_event_sample_ok (psample)) | |
238 | { | |
239 | warning (_("Branch trace may be incomplete.")); | |
240 | break; | |
241 | } | |
242 | ||
243 | if (perf_event_skip_record (tinfo, &psample->bts)) | |
244 | continue; | |
245 | ||
246 | /* We found a valid sample, so we can complete the current block. */ | |
247 | block.begin = psample->bts.to; | |
248 | ||
249 | VEC_safe_push (btrace_block_s, btrace, &block); | |
250 | ||
251 | /* Start the next block. */ | |
252 | block.end = psample->bts.from; | |
253 | } | |
254 | ||
969c39fb MM |
255 | /* Push the last block (i.e. the first one of inferior execution), as well. |
256 | We don't know where it ends, but we know where it starts. If we're | |
257 | reading delta trace, we can fill in the start address later on. | |
258 | Otherwise we will prune it. */ | |
259 | block.begin = 0; | |
260 | VEC_safe_push (btrace_block_s, btrace, &block); | |
261 | ||
7c97f91e MM |
262 | return btrace; |
263 | } | |
264 | ||
a950d57c MM |
265 | /* Check whether the kernel supports branch tracing. */ |
266 | ||
267 | static int | |
268 | kernel_supports_btrace (void) | |
269 | { | |
270 | struct perf_event_attr attr; | |
271 | pid_t child, pid; | |
272 | int status, file; | |
273 | ||
274 | errno = 0; | |
275 | child = fork (); | |
276 | switch (child) | |
277 | { | |
278 | case -1: | |
279 | warning (_("test branch tracing: cannot fork: %s."), strerror (errno)); | |
280 | return 0; | |
281 | ||
282 | case 0: | |
283 | status = ptrace (PTRACE_TRACEME, 0, NULL, NULL); | |
284 | if (status != 0) | |
285 | { | |
286 | warning (_("test branch tracing: cannot PTRACE_TRACEME: %s."), | |
287 | strerror (errno)); | |
288 | _exit (1); | |
289 | } | |
290 | ||
291 | status = raise (SIGTRAP); | |
292 | if (status != 0) | |
293 | { | |
294 | warning (_("test branch tracing: cannot raise SIGTRAP: %s."), | |
295 | strerror (errno)); | |
296 | _exit (1); | |
297 | } | |
298 | ||
299 | _exit (1); | |
300 | ||
301 | default: | |
302 | pid = waitpid (child, &status, 0); | |
303 | if (pid != child) | |
304 | { | |
305 | warning (_("test branch tracing: bad pid %ld, error: %s."), | |
306 | (long) pid, strerror (errno)); | |
307 | return 0; | |
308 | } | |
309 | ||
310 | if (!WIFSTOPPED (status)) | |
311 | { | |
312 | warning (_("test branch tracing: expected stop. status: %d."), | |
313 | status); | |
314 | return 0; | |
315 | } | |
316 | ||
317 | memset (&attr, 0, sizeof (attr)); | |
318 | ||
319 | attr.type = PERF_TYPE_HARDWARE; | |
320 | attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; | |
321 | attr.sample_period = 1; | |
322 | attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; | |
323 | attr.exclude_kernel = 1; | |
324 | attr.exclude_hv = 1; | |
325 | attr.exclude_idle = 1; | |
326 | ||
327 | file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0); | |
328 | if (file >= 0) | |
329 | close (file); | |
330 | ||
331 | kill (child, SIGKILL); | |
332 | ptrace (PTRACE_KILL, child, NULL, NULL); | |
333 | ||
334 | pid = waitpid (child, &status, 0); | |
335 | if (pid != child) | |
336 | { | |
337 | warning (_("test branch tracing: bad pid %ld, error: %s."), | |
338 | (long) pid, strerror (errno)); | |
339 | if (!WIFSIGNALED (status)) | |
340 | warning (_("test branch tracing: expected killed. status: %d."), | |
341 | status); | |
342 | } | |
343 | ||
344 | return (file >= 0); | |
345 | } | |
346 | } | |
347 | ||
348 | /* Check whether an Intel cpu supports branch tracing. */ | |
349 | ||
350 | static int | |
351 | intel_supports_btrace (void) | |
352 | { | |
5f8e0b8f MF |
353 | unsigned int cpuid, model, family; |
354 | ||
4d157a3d MF |
355 | if (!i386_cpuid (1, &cpuid, NULL, NULL, NULL)) |
356 | return 0; | |
5f8e0b8f MF |
357 | |
358 | family = (cpuid >> 8) & 0xf; | |
359 | model = (cpuid >> 4) & 0xf; | |
360 | ||
361 | switch (family) | |
362 | { | |
363 | case 0x6: | |
364 | model += (cpuid >> 12) & 0xf0; | |
365 | ||
366 | switch (model) | |
367 | { | |
368 | case 0x1a: /* Nehalem */ | |
369 | case 0x1f: | |
370 | case 0x1e: | |
371 | case 0x2e: | |
372 | case 0x25: /* Westmere */ | |
373 | case 0x2c: | |
374 | case 0x2f: | |
375 | case 0x2a: /* Sandy Bridge */ | |
376 | case 0x2d: | |
377 | case 0x3a: /* Ivy Bridge */ | |
378 | ||
379 | /* AAJ122: LBR, BTM, or BTS records may have incorrect branch | |
380 | "from" information afer an EIST transition, T-states, C1E, or | |
381 | Adaptive Thermal Throttling. */ | |
382 | return 0; | |
383 | } | |
384 | } | |
a950d57c MM |
385 | |
386 | return 1; | |
a950d57c MM |
387 | } |
388 | ||
389 | /* Check whether the cpu supports branch tracing. */ | |
390 | ||
391 | static int | |
392 | cpu_supports_btrace (void) | |
393 | { | |
4d157a3d | 394 | unsigned int ebx, ecx, edx; |
a950d57c | 395 | |
4d157a3d MF |
396 | if (!i386_cpuid (0, NULL, &ebx, &ecx, &edx)) |
397 | return 0; | |
398 | ||
4353c9e6 JK |
399 | if (ebx == signature_INTEL_ebx && ecx == signature_INTEL_ecx |
400 | && edx == signature_INTEL_edx) | |
a950d57c MM |
401 | return intel_supports_btrace (); |
402 | ||
403 | /* Don't know about others. Let's assume they do. */ | |
404 | return 1; | |
a950d57c MM |
405 | } |
406 | ||
7c97f91e MM |
407 | /* See linux-btrace.h. */ |
408 | ||
409 | int | |
410 | linux_supports_btrace (void) | |
411 | { | |
a950d57c MM |
412 | static int cached; |
413 | ||
414 | if (cached == 0) | |
415 | { | |
416 | if (!kernel_supports_btrace ()) | |
417 | cached = -1; | |
418 | else if (!cpu_supports_btrace ()) | |
419 | cached = -1; | |
420 | else | |
421 | cached = 1; | |
422 | } | |
423 | ||
424 | return cached > 0; | |
7c97f91e MM |
425 | } |
426 | ||
427 | /* See linux-btrace.h. */ | |
428 | ||
429 | struct btrace_target_info * | |
430 | linux_enable_btrace (ptid_t ptid) | |
431 | { | |
432 | struct btrace_target_info *tinfo; | |
d0fa7535 | 433 | int pid, pg; |
7c97f91e MM |
434 | |
435 | tinfo = xzalloc (sizeof (*tinfo)); | |
436 | tinfo->ptid = ptid; | |
437 | ||
438 | tinfo->attr.size = sizeof (tinfo->attr); | |
439 | tinfo->attr.type = PERF_TYPE_HARDWARE; | |
440 | tinfo->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; | |
441 | tinfo->attr.sample_period = 1; | |
442 | ||
443 | /* We sample from and to address. */ | |
444 | tinfo->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; | |
445 | ||
446 | tinfo->attr.exclude_kernel = 1; | |
447 | tinfo->attr.exclude_hv = 1; | |
448 | tinfo->attr.exclude_idle = 1; | |
449 | ||
450 | tinfo->ptr_bits = 0; | |
451 | ||
452 | pid = ptid_get_lwp (ptid); | |
453 | if (pid == 0) | |
454 | pid = ptid_get_pid (ptid); | |
455 | ||
456 | errno = 0; | |
457 | tinfo->file = syscall (SYS_perf_event_open, &tinfo->attr, pid, -1, -1, 0); | |
458 | if (tinfo->file < 0) | |
459 | goto err; | |
460 | ||
d0fa7535 MM |
461 | /* We try to allocate as much buffer as we can get. |
462 | We could allow the user to specify the size of the buffer, but then | |
463 | we'd leave this search for the maximum buffer size to him. */ | |
464 | for (pg = 4; pg >= 0; --pg) | |
465 | { | |
466 | /* The number of pages we request needs to be a power of two. */ | |
467 | tinfo->size = 1 << pg; | |
468 | tinfo->buffer = mmap (NULL, perf_event_mmap_size (tinfo), | |
469 | PROT_READ, MAP_SHARED, tinfo->file, 0); | |
470 | if (tinfo->buffer == MAP_FAILED) | |
471 | continue; | |
7c97f91e | 472 | |
d0fa7535 MM |
473 | return tinfo; |
474 | } | |
7c97f91e | 475 | |
d0fa7535 | 476 | /* We were not able to allocate any buffer. */ |
7c97f91e MM |
477 | close (tinfo->file); |
478 | ||
479 | err: | |
480 | xfree (tinfo); | |
481 | return NULL; | |
482 | } | |
483 | ||
484 | /* See linux-btrace.h. */ | |
485 | ||
969c39fb | 486 | enum btrace_error |
7c97f91e MM |
487 | linux_disable_btrace (struct btrace_target_info *tinfo) |
488 | { | |
489 | int errcode; | |
490 | ||
491 | errno = 0; | |
492 | errcode = munmap (tinfo->buffer, perf_event_mmap_size (tinfo)); | |
493 | if (errcode != 0) | |
969c39fb | 494 | return BTRACE_ERR_UNKNOWN; |
7c97f91e MM |
495 | |
496 | close (tinfo->file); | |
497 | xfree (tinfo); | |
498 | ||
969c39fb | 499 | return BTRACE_ERR_NONE; |
7c97f91e MM |
500 | } |
501 | ||
502 | /* Check whether the branch trace has changed. */ | |
503 | ||
504 | static int | |
505 | linux_btrace_has_changed (struct btrace_target_info *tinfo) | |
506 | { | |
507 | volatile struct perf_event_mmap_page *header = perf_event_header (tinfo); | |
508 | ||
509 | return header->data_head != tinfo->data_head; | |
510 | } | |
511 | ||
512 | /* See linux-btrace.h. */ | |
513 | ||
969c39fb MM |
514 | enum btrace_error |
515 | linux_read_btrace (VEC (btrace_block_s) **btrace, | |
516 | struct btrace_target_info *tinfo, | |
7c97f91e MM |
517 | enum btrace_read_type type) |
518 | { | |
7c97f91e MM |
519 | volatile struct perf_event_mmap_page *header; |
520 | const uint8_t *begin, *end, *start; | |
969c39fb MM |
521 | unsigned long data_head, data_tail, retries = 5; |
522 | size_t buffer_size, size; | |
7c97f91e | 523 | |
969c39fb MM |
524 | /* For delta reads, we return at least the partial last block containing |
525 | the current PC. */ | |
864089d2 | 526 | if (type == BTRACE_READ_NEW && !linux_btrace_has_changed (tinfo)) |
969c39fb | 527 | return BTRACE_ERR_NONE; |
7c97f91e MM |
528 | |
529 | header = perf_event_header (tinfo); | |
530 | buffer_size = perf_event_buffer_size (tinfo); | |
969c39fb | 531 | data_tail = tinfo->data_head; |
7c97f91e MM |
532 | |
533 | /* We may need to retry reading the trace. See below. */ | |
534 | while (retries--) | |
535 | { | |
536 | data_head = header->data_head; | |
537 | ||
ed9edfb5 | 538 | /* Delete any leftover trace from the previous iteration. */ |
969c39fb | 539 | VEC_free (btrace_block_s, *btrace); |
ed9edfb5 | 540 | |
969c39fb | 541 | if (type == BTRACE_READ_DELTA) |
7c97f91e | 542 | { |
969c39fb MM |
543 | /* Determine the number of bytes to read and check for buffer |
544 | overflows. */ | |
545 | ||
546 | /* Check for data head overflows. We might be able to recover from | |
547 | those but they are very unlikely and it's not really worth the | |
548 | effort, I think. */ | |
549 | if (data_head < data_tail) | |
550 | return BTRACE_ERR_OVERFLOW; | |
551 | ||
552 | /* If the buffer is smaller than the trace delta, we overflowed. */ | |
553 | size = data_head - data_tail; | |
554 | if (buffer_size < size) | |
555 | return BTRACE_ERR_OVERFLOW; | |
556 | } | |
557 | else | |
558 | { | |
559 | /* Read the entire buffer. */ | |
560 | size = buffer_size; | |
7c97f91e | 561 | |
969c39fb MM |
562 | /* Adjust the size if the buffer has not overflowed, yet. */ |
563 | if (data_head < size) | |
564 | size = data_head; | |
7c97f91e MM |
565 | } |
566 | ||
969c39fb MM |
567 | /* Data_head keeps growing; the buffer itself is circular. */ |
568 | begin = perf_event_buffer_begin (tinfo); | |
569 | start = begin + data_head % buffer_size; | |
570 | ||
571 | if (data_head <= buffer_size) | |
572 | end = start; | |
573 | else | |
574 | end = perf_event_buffer_end (tinfo); | |
575 | ||
576 | *btrace = perf_event_read_bts (tinfo, begin, end, start, size); | |
577 | ||
7c97f91e MM |
578 | /* The stopping thread notifies its ptracer before it is scheduled out. |
579 | On multi-core systems, the debugger might therefore run while the | |
580 | kernel might be writing the last branch trace records. | |
581 | ||
582 | Let's check whether the data head moved while we read the trace. */ | |
583 | if (data_head == header->data_head) | |
584 | break; | |
585 | } | |
586 | ||
587 | tinfo->data_head = data_head; | |
588 | ||
969c39fb MM |
589 | /* Prune the incomplete last block (i.e. the first one of inferior execution) |
590 | if we're not doing a delta read. There is no way of filling in its zeroed | |
591 | BEGIN element. */ | |
592 | if (!VEC_empty (btrace_block_s, *btrace) && type != BTRACE_READ_DELTA) | |
593 | VEC_pop (btrace_block_s, *btrace); | |
594 | ||
595 | return BTRACE_ERR_NONE; | |
7c97f91e MM |
596 | } |
597 | ||
598 | #else /* !HAVE_LINUX_PERF_EVENT_H */ | |
599 | ||
600 | /* See linux-btrace.h. */ | |
601 | ||
602 | int | |
603 | linux_supports_btrace (void) | |
604 | { | |
605 | return 0; | |
606 | } | |
607 | ||
608 | /* See linux-btrace.h. */ | |
609 | ||
610 | struct btrace_target_info * | |
611 | linux_enable_btrace (ptid_t ptid) | |
612 | { | |
613 | return NULL; | |
614 | } | |
615 | ||
616 | /* See linux-btrace.h. */ | |
617 | ||
969c39fb | 618 | enum btrace_error |
7c97f91e MM |
619 | linux_disable_btrace (struct btrace_target_info *tinfo) |
620 | { | |
969c39fb | 621 | return BTRACE_ERR_NOT_SUPPORTED; |
7c97f91e MM |
622 | } |
623 | ||
624 | /* See linux-btrace.h. */ | |
625 | ||
969c39fb MM |
626 | enum btrace_error |
627 | linux_read_btrace (VEC (btrace_block_s) **btrace, | |
628 | struct btrace_target_info *tinfo, | |
7c97f91e MM |
629 | enum btrace_read_type type) |
630 | { | |
969c39fb | 631 | return BTRACE_ERR_NOT_SUPPORTED; |
7c97f91e MM |
632 | } |
633 | ||
634 | #endif /* !HAVE_LINUX_PERF_EVENT_H */ |