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