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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" | |
7c97f91e MM |
29 | #include "regcache.h" |
30 | #include "gdbthread.h" | |
be8b1ea6 | 31 | #include "gdb_wait.h" |
4d157a3d | 32 | #include "i386-cpuid.h" |
7c97f91e | 33 | |
5b4e221c MF |
34 | #ifdef HAVE_SYS_SYSCALL_H |
35 | #include <sys/syscall.h> | |
36 | #endif | |
37 | ||
38 | #if HAVE_LINUX_PERF_EVENT_H && defined(SYS_perf_event_open) | |
7c97f91e MM |
39 | |
40 | #include <errno.h> | |
41 | #include <string.h> | |
42 | #include <stdint.h> | |
43 | #include <unistd.h> | |
7c97f91e MM |
44 | #include <sys/mman.h> |
45 | #include <sys/user.h> | |
a950d57c MM |
46 | #include <sys/ptrace.h> |
47 | #include <sys/types.h> | |
a950d57c | 48 | #include <signal.h> |
7c97f91e MM |
49 | |
50 | /* A branch trace record in perf_event. */ | |
51 | struct perf_event_bts | |
52 | { | |
53 | /* The linear address of the branch source. */ | |
54 | uint64_t from; | |
55 | ||
56 | /* The linear address of the branch destination. */ | |
57 | uint64_t to; | |
58 | }; | |
59 | ||
60 | /* A perf_event branch trace sample. */ | |
61 | struct perf_event_sample | |
62 | { | |
63 | /* The perf_event sample header. */ | |
64 | struct perf_event_header header; | |
65 | ||
66 | /* The perf_event branch tracing payload. */ | |
67 | struct perf_event_bts bts; | |
68 | }; | |
69 | ||
70 | /* Get the perf_event header. */ | |
71 | ||
72 | static inline volatile struct perf_event_mmap_page * | |
73 | perf_event_header (struct btrace_target_info* tinfo) | |
74 | { | |
75 | return tinfo->buffer; | |
76 | } | |
77 | ||
78 | /* Get the size of the perf_event mmap buffer. */ | |
79 | ||
80 | static inline size_t | |
81 | perf_event_mmap_size (const struct btrace_target_info *tinfo) | |
82 | { | |
83 | /* The branch trace buffer is preceded by a configuration page. */ | |
84 | return (tinfo->size + 1) * PAGE_SIZE; | |
85 | } | |
86 | ||
87 | /* Get the size of the perf_event buffer. */ | |
88 | ||
89 | static inline size_t | |
90 | perf_event_buffer_size (struct btrace_target_info* tinfo) | |
91 | { | |
92 | return tinfo->size * PAGE_SIZE; | |
93 | } | |
94 | ||
95 | /* Get the start address of the perf_event buffer. */ | |
96 | ||
97 | static inline const uint8_t * | |
98 | perf_event_buffer_begin (struct btrace_target_info* tinfo) | |
99 | { | |
100 | return ((const uint8_t *) tinfo->buffer) + PAGE_SIZE; | |
101 | } | |
102 | ||
103 | /* Get the end address of the perf_event buffer. */ | |
104 | ||
105 | static inline const uint8_t * | |
106 | perf_event_buffer_end (struct btrace_target_info* tinfo) | |
107 | { | |
108 | return perf_event_buffer_begin (tinfo) + perf_event_buffer_size (tinfo); | |
109 | } | |
110 | ||
111 | /* Check whether an address is in the kernel. */ | |
112 | ||
113 | static inline int | |
114 | perf_event_is_kernel_addr (const struct btrace_target_info *tinfo, | |
115 | uint64_t addr) | |
116 | { | |
117 | uint64_t mask; | |
118 | ||
119 | /* If we don't know the size of a pointer, we can't check. Let's assume it's | |
120 | not a kernel address in this case. */ | |
121 | if (tinfo->ptr_bits == 0) | |
122 | return 0; | |
123 | ||
124 | /* A bit mask for the most significant bit in an address. */ | |
125 | mask = (uint64_t) 1 << (tinfo->ptr_bits - 1); | |
126 | ||
127 | /* Check whether the most significant bit in the address is set. */ | |
128 | return (addr & mask) != 0; | |
129 | } | |
130 | ||
131 | /* Check whether a perf event record should be skipped. */ | |
132 | ||
133 | static inline int | |
134 | perf_event_skip_record (const struct btrace_target_info *tinfo, | |
135 | const struct perf_event_bts *bts) | |
136 | { | |
137 | /* The hardware may report branches from kernel into user space. Branches | |
138 | from user into kernel space will be suppressed. We filter the former to | |
139 | provide a consistent branch trace excluding kernel. */ | |
140 | return perf_event_is_kernel_addr (tinfo, bts->from); | |
141 | } | |
142 | ||
143 | /* Perform a few consistency checks on a perf event sample record. This is | |
144 | meant to catch cases when we get out of sync with the perf event stream. */ | |
145 | ||
146 | static inline int | |
147 | perf_event_sample_ok (const struct perf_event_sample *sample) | |
148 | { | |
149 | if (sample->header.type != PERF_RECORD_SAMPLE) | |
150 | return 0; | |
151 | ||
152 | if (sample->header.size != sizeof (*sample)) | |
153 | return 0; | |
154 | ||
155 | return 1; | |
156 | } | |
157 | ||
158 | /* Branch trace is collected in a circular buffer [begin; end) as pairs of from | |
159 | and to addresses (plus a header). | |
160 | ||
161 | Start points into that buffer at the next sample position. | |
162 | We read the collected samples backwards from start. | |
163 | ||
164 | While reading the samples, we convert the information into a list of blocks. | |
165 | For two adjacent samples s1 and s2, we form a block b such that b.begin = | |
166 | s1.to and b.end = s2.from. | |
167 | ||
168 | In case the buffer overflows during sampling, one sample may have its lower | |
169 | part at the end and its upper part at the beginning of the buffer. */ | |
170 | ||
171 | static VEC (btrace_block_s) * | |
172 | perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin, | |
969c39fb | 173 | const uint8_t *end, const uint8_t *start, size_t size) |
7c97f91e MM |
174 | { |
175 | VEC (btrace_block_s) *btrace = NULL; | |
176 | struct perf_event_sample sample; | |
969c39fb | 177 | size_t read = 0; |
7c97f91e MM |
178 | struct btrace_block block = { 0, 0 }; |
179 | struct regcache *regcache; | |
180 | ||
181 | gdb_assert (begin <= start); | |
182 | gdb_assert (start <= end); | |
183 | ||
184 | /* The first block ends at the current pc. */ | |
185 | #ifdef GDBSERVER | |
186 | regcache = get_thread_regcache (find_thread_ptid (tinfo->ptid), 1); | |
187 | #else | |
188 | regcache = get_thread_regcache (tinfo->ptid); | |
189 | #endif | |
190 | block.end = regcache_read_pc (regcache); | |
191 | ||
192 | /* The buffer may contain a partial record as its last entry (i.e. when the | |
193 | buffer size is not a multiple of the sample size). */ | |
194 | read = sizeof (sample) - 1; | |
195 | ||
196 | for (; read < size; read += sizeof (sample)) | |
197 | { | |
198 | const struct perf_event_sample *psample; | |
199 | ||
200 | /* Find the next perf_event sample in a backwards traversal. */ | |
201 | start -= sizeof (sample); | |
202 | ||
203 | /* If we're still inside the buffer, we're done. */ | |
204 | if (begin <= start) | |
205 | psample = (const struct perf_event_sample *) start; | |
206 | else | |
207 | { | |
208 | int missing; | |
209 | ||
210 | /* We're to the left of the ring buffer, we will wrap around and | |
211 | reappear at the very right of the ring buffer. */ | |
212 | ||
213 | missing = (begin - start); | |
214 | start = (end - missing); | |
215 | ||
216 | /* If the entire sample is missing, we're done. */ | |
217 | if (missing == sizeof (sample)) | |
218 | psample = (const struct perf_event_sample *) start; | |
219 | else | |
220 | { | |
221 | uint8_t *stack; | |
222 | ||
223 | /* The sample wrapped around. The lower part is at the end and | |
224 | the upper part is at the beginning of the buffer. */ | |
225 | stack = (uint8_t *) &sample; | |
226 | ||
227 | /* Copy the two parts so we have a contiguous sample. */ | |
228 | memcpy (stack, start, missing); | |
229 | memcpy (stack + missing, begin, sizeof (sample) - missing); | |
230 | ||
231 | psample = &sample; | |
232 | } | |
233 | } | |
234 | ||
235 | if (!perf_event_sample_ok (psample)) | |
236 | { | |
237 | warning (_("Branch trace may be incomplete.")); | |
238 | break; | |
239 | } | |
240 | ||
241 | if (perf_event_skip_record (tinfo, &psample->bts)) | |
242 | continue; | |
243 | ||
244 | /* We found a valid sample, so we can complete the current block. */ | |
245 | block.begin = psample->bts.to; | |
246 | ||
247 | VEC_safe_push (btrace_block_s, btrace, &block); | |
248 | ||
249 | /* Start the next block. */ | |
250 | block.end = psample->bts.from; | |
251 | } | |
252 | ||
969c39fb MM |
253 | /* Push the last block (i.e. the first one of inferior execution), as well. |
254 | We don't know where it ends, but we know where it starts. If we're | |
255 | reading delta trace, we can fill in the start address later on. | |
256 | Otherwise we will prune it. */ | |
257 | block.begin = 0; | |
258 | VEC_safe_push (btrace_block_s, btrace, &block); | |
259 | ||
7c97f91e MM |
260 | return btrace; |
261 | } | |
262 | ||
a950d57c MM |
263 | /* Check whether the kernel supports branch tracing. */ |
264 | ||
265 | static int | |
266 | kernel_supports_btrace (void) | |
267 | { | |
268 | struct perf_event_attr attr; | |
269 | pid_t child, pid; | |
270 | int status, file; | |
271 | ||
272 | errno = 0; | |
273 | child = fork (); | |
274 | switch (child) | |
275 | { | |
276 | case -1: | |
277 | warning (_("test branch tracing: cannot fork: %s."), strerror (errno)); | |
278 | return 0; | |
279 | ||
280 | case 0: | |
281 | status = ptrace (PTRACE_TRACEME, 0, NULL, NULL); | |
282 | if (status != 0) | |
283 | { | |
284 | warning (_("test branch tracing: cannot PTRACE_TRACEME: %s."), | |
285 | strerror (errno)); | |
286 | _exit (1); | |
287 | } | |
288 | ||
289 | status = raise (SIGTRAP); | |
290 | if (status != 0) | |
291 | { | |
292 | warning (_("test branch tracing: cannot raise SIGTRAP: %s."), | |
293 | strerror (errno)); | |
294 | _exit (1); | |
295 | } | |
296 | ||
297 | _exit (1); | |
298 | ||
299 | default: | |
300 | pid = waitpid (child, &status, 0); | |
301 | if (pid != child) | |
302 | { | |
303 | warning (_("test branch tracing: bad pid %ld, error: %s."), | |
304 | (long) pid, strerror (errno)); | |
305 | return 0; | |
306 | } | |
307 | ||
308 | if (!WIFSTOPPED (status)) | |
309 | { | |
310 | warning (_("test branch tracing: expected stop. status: %d."), | |
311 | status); | |
312 | return 0; | |
313 | } | |
314 | ||
315 | memset (&attr, 0, sizeof (attr)); | |
316 | ||
317 | attr.type = PERF_TYPE_HARDWARE; | |
318 | attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; | |
319 | attr.sample_period = 1; | |
320 | attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; | |
321 | attr.exclude_kernel = 1; | |
322 | attr.exclude_hv = 1; | |
323 | attr.exclude_idle = 1; | |
324 | ||
325 | file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0); | |
326 | if (file >= 0) | |
327 | close (file); | |
328 | ||
329 | kill (child, SIGKILL); | |
330 | ptrace (PTRACE_KILL, child, NULL, NULL); | |
331 | ||
332 | pid = waitpid (child, &status, 0); | |
333 | if (pid != child) | |
334 | { | |
335 | warning (_("test branch tracing: bad pid %ld, error: %s."), | |
336 | (long) pid, strerror (errno)); | |
337 | if (!WIFSIGNALED (status)) | |
338 | warning (_("test branch tracing: expected killed. status: %d."), | |
339 | status); | |
340 | } | |
341 | ||
342 | return (file >= 0); | |
343 | } | |
344 | } | |
345 | ||
346 | /* Check whether an Intel cpu supports branch tracing. */ | |
347 | ||
348 | static int | |
349 | intel_supports_btrace (void) | |
350 | { | |
5f8e0b8f MF |
351 | unsigned int cpuid, model, family; |
352 | ||
4d157a3d MF |
353 | if (!i386_cpuid (1, &cpuid, NULL, NULL, NULL)) |
354 | return 0; | |
5f8e0b8f MF |
355 | |
356 | family = (cpuid >> 8) & 0xf; | |
357 | model = (cpuid >> 4) & 0xf; | |
358 | ||
359 | switch (family) | |
360 | { | |
361 | case 0x6: | |
362 | model += (cpuid >> 12) & 0xf0; | |
363 | ||
364 | switch (model) | |
365 | { | |
366 | case 0x1a: /* Nehalem */ | |
367 | case 0x1f: | |
368 | case 0x1e: | |
369 | case 0x2e: | |
370 | case 0x25: /* Westmere */ | |
371 | case 0x2c: | |
372 | case 0x2f: | |
373 | case 0x2a: /* Sandy Bridge */ | |
374 | case 0x2d: | |
375 | case 0x3a: /* Ivy Bridge */ | |
376 | ||
377 | /* AAJ122: LBR, BTM, or BTS records may have incorrect branch | |
378 | "from" information afer an EIST transition, T-states, C1E, or | |
379 | Adaptive Thermal Throttling. */ | |
380 | return 0; | |
381 | } | |
382 | } | |
a950d57c MM |
383 | |
384 | return 1; | |
a950d57c MM |
385 | } |
386 | ||
387 | /* Check whether the cpu supports branch tracing. */ | |
388 | ||
389 | static int | |
390 | cpu_supports_btrace (void) | |
391 | { | |
4d157a3d | 392 | unsigned int ebx, ecx, edx; |
a950d57c | 393 | |
4d157a3d MF |
394 | if (!i386_cpuid (0, NULL, &ebx, &ecx, &edx)) |
395 | return 0; | |
396 | ||
4353c9e6 JK |
397 | if (ebx == signature_INTEL_ebx && ecx == signature_INTEL_ecx |
398 | && edx == signature_INTEL_edx) | |
a950d57c MM |
399 | return intel_supports_btrace (); |
400 | ||
401 | /* Don't know about others. Let's assume they do. */ | |
402 | return 1; | |
a950d57c MM |
403 | } |
404 | ||
7c97f91e MM |
405 | /* See linux-btrace.h. */ |
406 | ||
407 | int | |
46917d26 | 408 | linux_supports_btrace (struct target_ops *ops) |
7c97f91e | 409 | { |
a950d57c MM |
410 | static int cached; |
411 | ||
412 | if (cached == 0) | |
413 | { | |
414 | if (!kernel_supports_btrace ()) | |
415 | cached = -1; | |
416 | else if (!cpu_supports_btrace ()) | |
417 | cached = -1; | |
418 | else | |
419 | cached = 1; | |
420 | } | |
421 | ||
422 | return cached > 0; | |
7c97f91e MM |
423 | } |
424 | ||
425 | /* See linux-btrace.h. */ | |
426 | ||
427 | struct btrace_target_info * | |
428 | linux_enable_btrace (ptid_t ptid) | |
429 | { | |
430 | struct btrace_target_info *tinfo; | |
d0fa7535 | 431 | int pid, pg; |
7c97f91e MM |
432 | |
433 | tinfo = xzalloc (sizeof (*tinfo)); | |
434 | tinfo->ptid = ptid; | |
435 | ||
436 | tinfo->attr.size = sizeof (tinfo->attr); | |
437 | tinfo->attr.type = PERF_TYPE_HARDWARE; | |
438 | tinfo->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; | |
439 | tinfo->attr.sample_period = 1; | |
440 | ||
441 | /* We sample from and to address. */ | |
442 | tinfo->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; | |
443 | ||
444 | tinfo->attr.exclude_kernel = 1; | |
445 | tinfo->attr.exclude_hv = 1; | |
446 | tinfo->attr.exclude_idle = 1; | |
447 | ||
448 | tinfo->ptr_bits = 0; | |
449 | ||
450 | pid = ptid_get_lwp (ptid); | |
451 | if (pid == 0) | |
452 | pid = ptid_get_pid (ptid); | |
453 | ||
454 | errno = 0; | |
455 | tinfo->file = syscall (SYS_perf_event_open, &tinfo->attr, pid, -1, -1, 0); | |
456 | if (tinfo->file < 0) | |
457 | goto err; | |
458 | ||
d0fa7535 MM |
459 | /* We try to allocate as much buffer as we can get. |
460 | We could allow the user to specify the size of the buffer, but then | |
461 | we'd leave this search for the maximum buffer size to him. */ | |
462 | for (pg = 4; pg >= 0; --pg) | |
463 | { | |
464 | /* The number of pages we request needs to be a power of two. */ | |
465 | tinfo->size = 1 << pg; | |
466 | tinfo->buffer = mmap (NULL, perf_event_mmap_size (tinfo), | |
467 | PROT_READ, MAP_SHARED, tinfo->file, 0); | |
468 | if (tinfo->buffer == MAP_FAILED) | |
469 | continue; | |
7c97f91e | 470 | |
d0fa7535 MM |
471 | return tinfo; |
472 | } | |
7c97f91e | 473 | |
d0fa7535 | 474 | /* We were not able to allocate any buffer. */ |
7c97f91e MM |
475 | close (tinfo->file); |
476 | ||
477 | err: | |
478 | xfree (tinfo); | |
479 | return NULL; | |
480 | } | |
481 | ||
482 | /* See linux-btrace.h. */ | |
483 | ||
969c39fb | 484 | enum btrace_error |
7c97f91e MM |
485 | linux_disable_btrace (struct btrace_target_info *tinfo) |
486 | { | |
487 | int errcode; | |
488 | ||
489 | errno = 0; | |
490 | errcode = munmap (tinfo->buffer, perf_event_mmap_size (tinfo)); | |
491 | if (errcode != 0) | |
969c39fb | 492 | return BTRACE_ERR_UNKNOWN; |
7c97f91e MM |
493 | |
494 | close (tinfo->file); | |
495 | xfree (tinfo); | |
496 | ||
969c39fb | 497 | return BTRACE_ERR_NONE; |
7c97f91e MM |
498 | } |
499 | ||
500 | /* Check whether the branch trace has changed. */ | |
501 | ||
502 | static int | |
503 | linux_btrace_has_changed (struct btrace_target_info *tinfo) | |
504 | { | |
505 | volatile struct perf_event_mmap_page *header = perf_event_header (tinfo); | |
506 | ||
507 | return header->data_head != tinfo->data_head; | |
508 | } | |
509 | ||
510 | /* See linux-btrace.h. */ | |
511 | ||
969c39fb MM |
512 | enum btrace_error |
513 | linux_read_btrace (VEC (btrace_block_s) **btrace, | |
514 | struct btrace_target_info *tinfo, | |
7c97f91e MM |
515 | enum btrace_read_type type) |
516 | { | |
7c97f91e MM |
517 | volatile struct perf_event_mmap_page *header; |
518 | const uint8_t *begin, *end, *start; | |
969c39fb MM |
519 | unsigned long data_head, data_tail, retries = 5; |
520 | size_t buffer_size, size; | |
7c97f91e | 521 | |
969c39fb MM |
522 | /* For delta reads, we return at least the partial last block containing |
523 | the current PC. */ | |
864089d2 | 524 | if (type == BTRACE_READ_NEW && !linux_btrace_has_changed (tinfo)) |
969c39fb | 525 | return BTRACE_ERR_NONE; |
7c97f91e MM |
526 | |
527 | header = perf_event_header (tinfo); | |
528 | buffer_size = perf_event_buffer_size (tinfo); | |
969c39fb | 529 | data_tail = tinfo->data_head; |
7c97f91e MM |
530 | |
531 | /* We may need to retry reading the trace. See below. */ | |
532 | while (retries--) | |
533 | { | |
534 | data_head = header->data_head; | |
535 | ||
ed9edfb5 | 536 | /* Delete any leftover trace from the previous iteration. */ |
969c39fb | 537 | VEC_free (btrace_block_s, *btrace); |
ed9edfb5 | 538 | |
969c39fb | 539 | if (type == BTRACE_READ_DELTA) |
7c97f91e | 540 | { |
969c39fb MM |
541 | /* Determine the number of bytes to read and check for buffer |
542 | overflows. */ | |
543 | ||
544 | /* Check for data head overflows. We might be able to recover from | |
545 | those but they are very unlikely and it's not really worth the | |
546 | effort, I think. */ | |
547 | if (data_head < data_tail) | |
548 | return BTRACE_ERR_OVERFLOW; | |
549 | ||
550 | /* If the buffer is smaller than the trace delta, we overflowed. */ | |
551 | size = data_head - data_tail; | |
552 | if (buffer_size < size) | |
553 | return BTRACE_ERR_OVERFLOW; | |
554 | } | |
555 | else | |
556 | { | |
557 | /* Read the entire buffer. */ | |
558 | size = buffer_size; | |
7c97f91e | 559 | |
969c39fb MM |
560 | /* Adjust the size if the buffer has not overflowed, yet. */ |
561 | if (data_head < size) | |
562 | size = data_head; | |
7c97f91e MM |
563 | } |
564 | ||
969c39fb MM |
565 | /* Data_head keeps growing; the buffer itself is circular. */ |
566 | begin = perf_event_buffer_begin (tinfo); | |
567 | start = begin + data_head % buffer_size; | |
568 | ||
569 | if (data_head <= buffer_size) | |
570 | end = start; | |
571 | else | |
572 | end = perf_event_buffer_end (tinfo); | |
573 | ||
574 | *btrace = perf_event_read_bts (tinfo, begin, end, start, size); | |
575 | ||
7c97f91e MM |
576 | /* The stopping thread notifies its ptracer before it is scheduled out. |
577 | On multi-core systems, the debugger might therefore run while the | |
578 | kernel might be writing the last branch trace records. | |
579 | ||
580 | Let's check whether the data head moved while we read the trace. */ | |
581 | if (data_head == header->data_head) | |
582 | break; | |
583 | } | |
584 | ||
585 | tinfo->data_head = data_head; | |
586 | ||
969c39fb MM |
587 | /* Prune the incomplete last block (i.e. the first one of inferior execution) |
588 | if we're not doing a delta read. There is no way of filling in its zeroed | |
589 | BEGIN element. */ | |
590 | if (!VEC_empty (btrace_block_s, *btrace) && type != BTRACE_READ_DELTA) | |
591 | VEC_pop (btrace_block_s, *btrace); | |
592 | ||
593 | return BTRACE_ERR_NONE; | |
7c97f91e MM |
594 | } |
595 | ||
596 | #else /* !HAVE_LINUX_PERF_EVENT_H */ | |
597 | ||
598 | /* See linux-btrace.h. */ | |
599 | ||
600 | int | |
46917d26 | 601 | linux_supports_btrace (struct target_ops *ops) |
7c97f91e MM |
602 | { |
603 | return 0; | |
604 | } | |
605 | ||
606 | /* See linux-btrace.h. */ | |
607 | ||
608 | struct btrace_target_info * | |
609 | linux_enable_btrace (ptid_t ptid) | |
610 | { | |
611 | return NULL; | |
612 | } | |
613 | ||
614 | /* See linux-btrace.h. */ | |
615 | ||
969c39fb | 616 | enum btrace_error |
7c97f91e MM |
617 | linux_disable_btrace (struct btrace_target_info *tinfo) |
618 | { | |
969c39fb | 619 | return BTRACE_ERR_NOT_SUPPORTED; |
7c97f91e MM |
620 | } |
621 | ||
622 | /* See linux-btrace.h. */ | |
623 | ||
969c39fb MM |
624 | enum btrace_error |
625 | linux_read_btrace (VEC (btrace_block_s) **btrace, | |
626 | struct btrace_target_info *tinfo, | |
7c97f91e MM |
627 | enum btrace_read_type type) |
628 | { | |
969c39fb | 629 | return BTRACE_ERR_NOT_SUPPORTED; |
7c97f91e MM |
630 | } |
631 | ||
632 | #endif /* !HAVE_LINUX_PERF_EVENT_H */ |