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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" | |
361c8ade | 29 | #include "common-regcache.h" |
7c97f91e | 30 | #include "gdbthread.h" |
be8b1ea6 | 31 | #include "gdb_wait.h" |
df7e5265 | 32 | #include "x86-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. */ | |
361c8ade | 183 | regcache = get_thread_regcache_for_ptid (tinfo->ptid); |
7c97f91e MM |
184 | block.end = regcache_read_pc (regcache); |
185 | ||
186 | /* The buffer may contain a partial record as its last entry (i.e. when the | |
187 | buffer size is not a multiple of the sample size). */ | |
188 | read = sizeof (sample) - 1; | |
189 | ||
190 | for (; read < size; read += sizeof (sample)) | |
191 | { | |
192 | const struct perf_event_sample *psample; | |
193 | ||
194 | /* Find the next perf_event sample in a backwards traversal. */ | |
195 | start -= sizeof (sample); | |
196 | ||
197 | /* If we're still inside the buffer, we're done. */ | |
198 | if (begin <= start) | |
199 | psample = (const struct perf_event_sample *) start; | |
200 | else | |
201 | { | |
202 | int missing; | |
203 | ||
204 | /* We're to the left of the ring buffer, we will wrap around and | |
205 | reappear at the very right of the ring buffer. */ | |
206 | ||
207 | missing = (begin - start); | |
208 | start = (end - missing); | |
209 | ||
210 | /* If the entire sample is missing, we're done. */ | |
211 | if (missing == sizeof (sample)) | |
212 | psample = (const struct perf_event_sample *) start; | |
213 | else | |
214 | { | |
215 | uint8_t *stack; | |
216 | ||
217 | /* The sample wrapped around. The lower part is at the end and | |
218 | the upper part is at the beginning of the buffer. */ | |
219 | stack = (uint8_t *) &sample; | |
220 | ||
221 | /* Copy the two parts so we have a contiguous sample. */ | |
222 | memcpy (stack, start, missing); | |
223 | memcpy (stack + missing, begin, sizeof (sample) - missing); | |
224 | ||
225 | psample = &sample; | |
226 | } | |
227 | } | |
228 | ||
229 | if (!perf_event_sample_ok (psample)) | |
230 | { | |
231 | warning (_("Branch trace may be incomplete.")); | |
232 | break; | |
233 | } | |
234 | ||
235 | if (perf_event_skip_record (tinfo, &psample->bts)) | |
236 | continue; | |
237 | ||
238 | /* We found a valid sample, so we can complete the current block. */ | |
239 | block.begin = psample->bts.to; | |
240 | ||
241 | VEC_safe_push (btrace_block_s, btrace, &block); | |
242 | ||
243 | /* Start the next block. */ | |
244 | block.end = psample->bts.from; | |
245 | } | |
246 | ||
969c39fb MM |
247 | /* Push the last block (i.e. the first one of inferior execution), as well. |
248 | We don't know where it ends, but we know where it starts. If we're | |
249 | reading delta trace, we can fill in the start address later on. | |
250 | Otherwise we will prune it. */ | |
251 | block.begin = 0; | |
252 | VEC_safe_push (btrace_block_s, btrace, &block); | |
253 | ||
7c97f91e MM |
254 | return btrace; |
255 | } | |
256 | ||
a950d57c MM |
257 | /* Check whether the kernel supports branch tracing. */ |
258 | ||
259 | static int | |
260 | kernel_supports_btrace (void) | |
261 | { | |
262 | struct perf_event_attr attr; | |
263 | pid_t child, pid; | |
264 | int status, file; | |
265 | ||
266 | errno = 0; | |
267 | child = fork (); | |
268 | switch (child) | |
269 | { | |
270 | case -1: | |
271 | warning (_("test branch tracing: cannot fork: %s."), strerror (errno)); | |
272 | return 0; | |
273 | ||
274 | case 0: | |
275 | status = ptrace (PTRACE_TRACEME, 0, NULL, NULL); | |
276 | if (status != 0) | |
277 | { | |
278 | warning (_("test branch tracing: cannot PTRACE_TRACEME: %s."), | |
279 | strerror (errno)); | |
280 | _exit (1); | |
281 | } | |
282 | ||
283 | status = raise (SIGTRAP); | |
284 | if (status != 0) | |
285 | { | |
286 | warning (_("test branch tracing: cannot raise SIGTRAP: %s."), | |
287 | strerror (errno)); | |
288 | _exit (1); | |
289 | } | |
290 | ||
291 | _exit (1); | |
292 | ||
293 | default: | |
294 | pid = waitpid (child, &status, 0); | |
295 | if (pid != child) | |
296 | { | |
297 | warning (_("test branch tracing: bad pid %ld, error: %s."), | |
298 | (long) pid, strerror (errno)); | |
299 | return 0; | |
300 | } | |
301 | ||
302 | if (!WIFSTOPPED (status)) | |
303 | { | |
304 | warning (_("test branch tracing: expected stop. status: %d."), | |
305 | status); | |
306 | return 0; | |
307 | } | |
308 | ||
309 | memset (&attr, 0, sizeof (attr)); | |
310 | ||
311 | attr.type = PERF_TYPE_HARDWARE; | |
312 | attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; | |
313 | attr.sample_period = 1; | |
314 | attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; | |
315 | attr.exclude_kernel = 1; | |
316 | attr.exclude_hv = 1; | |
317 | attr.exclude_idle = 1; | |
318 | ||
319 | file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0); | |
320 | if (file >= 0) | |
321 | close (file); | |
322 | ||
323 | kill (child, SIGKILL); | |
324 | ptrace (PTRACE_KILL, child, NULL, NULL); | |
325 | ||
326 | pid = waitpid (child, &status, 0); | |
327 | if (pid != child) | |
328 | { | |
329 | warning (_("test branch tracing: bad pid %ld, error: %s."), | |
330 | (long) pid, strerror (errno)); | |
331 | if (!WIFSIGNALED (status)) | |
332 | warning (_("test branch tracing: expected killed. status: %d."), | |
333 | status); | |
334 | } | |
335 | ||
336 | return (file >= 0); | |
337 | } | |
338 | } | |
339 | ||
340 | /* Check whether an Intel cpu supports branch tracing. */ | |
341 | ||
342 | static int | |
343 | intel_supports_btrace (void) | |
344 | { | |
5f8e0b8f MF |
345 | unsigned int cpuid, model, family; |
346 | ||
df7e5265 | 347 | if (!x86_cpuid (1, &cpuid, NULL, NULL, NULL)) |
4d157a3d | 348 | return 0; |
5f8e0b8f MF |
349 | |
350 | family = (cpuid >> 8) & 0xf; | |
351 | model = (cpuid >> 4) & 0xf; | |
352 | ||
353 | switch (family) | |
354 | { | |
355 | case 0x6: | |
356 | model += (cpuid >> 12) & 0xf0; | |
357 | ||
358 | switch (model) | |
359 | { | |
360 | case 0x1a: /* Nehalem */ | |
361 | case 0x1f: | |
362 | case 0x1e: | |
363 | case 0x2e: | |
364 | case 0x25: /* Westmere */ | |
365 | case 0x2c: | |
366 | case 0x2f: | |
367 | case 0x2a: /* Sandy Bridge */ | |
368 | case 0x2d: | |
369 | case 0x3a: /* Ivy Bridge */ | |
370 | ||
371 | /* AAJ122: LBR, BTM, or BTS records may have incorrect branch | |
372 | "from" information afer an EIST transition, T-states, C1E, or | |
373 | Adaptive Thermal Throttling. */ | |
374 | return 0; | |
375 | } | |
376 | } | |
a950d57c MM |
377 | |
378 | return 1; | |
a950d57c MM |
379 | } |
380 | ||
381 | /* Check whether the cpu supports branch tracing. */ | |
382 | ||
383 | static int | |
384 | cpu_supports_btrace (void) | |
385 | { | |
4d157a3d | 386 | unsigned int ebx, ecx, edx; |
a950d57c | 387 | |
df7e5265 | 388 | if (!x86_cpuid (0, NULL, &ebx, &ecx, &edx)) |
4d157a3d MF |
389 | return 0; |
390 | ||
4353c9e6 JK |
391 | if (ebx == signature_INTEL_ebx && ecx == signature_INTEL_ecx |
392 | && edx == signature_INTEL_edx) | |
a950d57c MM |
393 | return intel_supports_btrace (); |
394 | ||
395 | /* Don't know about others. Let's assume they do. */ | |
396 | return 1; | |
a950d57c MM |
397 | } |
398 | ||
7c97f91e MM |
399 | /* See linux-btrace.h. */ |
400 | ||
401 | int | |
46917d26 | 402 | linux_supports_btrace (struct target_ops *ops) |
7c97f91e | 403 | { |
a950d57c MM |
404 | static int cached; |
405 | ||
406 | if (cached == 0) | |
407 | { | |
408 | if (!kernel_supports_btrace ()) | |
409 | cached = -1; | |
410 | else if (!cpu_supports_btrace ()) | |
411 | cached = -1; | |
412 | else | |
413 | cached = 1; | |
414 | } | |
415 | ||
416 | return cached > 0; | |
7c97f91e MM |
417 | } |
418 | ||
419 | /* See linux-btrace.h. */ | |
420 | ||
421 | struct btrace_target_info * | |
422 | linux_enable_btrace (ptid_t ptid) | |
423 | { | |
424 | struct btrace_target_info *tinfo; | |
d0fa7535 | 425 | int pid, pg; |
7c97f91e MM |
426 | |
427 | tinfo = xzalloc (sizeof (*tinfo)); | |
428 | tinfo->ptid = ptid; | |
429 | ||
430 | tinfo->attr.size = sizeof (tinfo->attr); | |
431 | tinfo->attr.type = PERF_TYPE_HARDWARE; | |
432 | tinfo->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; | |
433 | tinfo->attr.sample_period = 1; | |
434 | ||
435 | /* We sample from and to address. */ | |
436 | tinfo->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; | |
437 | ||
438 | tinfo->attr.exclude_kernel = 1; | |
439 | tinfo->attr.exclude_hv = 1; | |
440 | tinfo->attr.exclude_idle = 1; | |
441 | ||
442 | tinfo->ptr_bits = 0; | |
443 | ||
444 | pid = ptid_get_lwp (ptid); | |
445 | if (pid == 0) | |
446 | pid = ptid_get_pid (ptid); | |
447 | ||
448 | errno = 0; | |
449 | tinfo->file = syscall (SYS_perf_event_open, &tinfo->attr, pid, -1, -1, 0); | |
450 | if (tinfo->file < 0) | |
451 | goto err; | |
452 | ||
d0fa7535 MM |
453 | /* We try to allocate as much buffer as we can get. |
454 | We could allow the user to specify the size of the buffer, but then | |
455 | we'd leave this search for the maximum buffer size to him. */ | |
456 | for (pg = 4; pg >= 0; --pg) | |
457 | { | |
458 | /* The number of pages we request needs to be a power of two. */ | |
459 | tinfo->size = 1 << pg; | |
460 | tinfo->buffer = mmap (NULL, perf_event_mmap_size (tinfo), | |
461 | PROT_READ, MAP_SHARED, tinfo->file, 0); | |
462 | if (tinfo->buffer == MAP_FAILED) | |
463 | continue; | |
7c97f91e | 464 | |
d0fa7535 MM |
465 | return tinfo; |
466 | } | |
7c97f91e | 467 | |
d0fa7535 | 468 | /* We were not able to allocate any buffer. */ |
7c97f91e MM |
469 | close (tinfo->file); |
470 | ||
471 | err: | |
472 | xfree (tinfo); | |
473 | return NULL; | |
474 | } | |
475 | ||
476 | /* See linux-btrace.h. */ | |
477 | ||
969c39fb | 478 | enum btrace_error |
7c97f91e MM |
479 | linux_disable_btrace (struct btrace_target_info *tinfo) |
480 | { | |
481 | int errcode; | |
482 | ||
483 | errno = 0; | |
484 | errcode = munmap (tinfo->buffer, perf_event_mmap_size (tinfo)); | |
485 | if (errcode != 0) | |
969c39fb | 486 | return BTRACE_ERR_UNKNOWN; |
7c97f91e MM |
487 | |
488 | close (tinfo->file); | |
489 | xfree (tinfo); | |
490 | ||
969c39fb | 491 | return BTRACE_ERR_NONE; |
7c97f91e MM |
492 | } |
493 | ||
494 | /* Check whether the branch trace has changed. */ | |
495 | ||
496 | static int | |
497 | linux_btrace_has_changed (struct btrace_target_info *tinfo) | |
498 | { | |
499 | volatile struct perf_event_mmap_page *header = perf_event_header (tinfo); | |
500 | ||
501 | return header->data_head != tinfo->data_head; | |
502 | } | |
503 | ||
504 | /* See linux-btrace.h. */ | |
505 | ||
969c39fb MM |
506 | enum btrace_error |
507 | linux_read_btrace (VEC (btrace_block_s) **btrace, | |
508 | struct btrace_target_info *tinfo, | |
7c97f91e MM |
509 | enum btrace_read_type type) |
510 | { | |
7c97f91e MM |
511 | volatile struct perf_event_mmap_page *header; |
512 | const uint8_t *begin, *end, *start; | |
969c39fb MM |
513 | unsigned long data_head, data_tail, retries = 5; |
514 | size_t buffer_size, size; | |
7c97f91e | 515 | |
969c39fb MM |
516 | /* For delta reads, we return at least the partial last block containing |
517 | the current PC. */ | |
864089d2 | 518 | if (type == BTRACE_READ_NEW && !linux_btrace_has_changed (tinfo)) |
969c39fb | 519 | return BTRACE_ERR_NONE; |
7c97f91e MM |
520 | |
521 | header = perf_event_header (tinfo); | |
522 | buffer_size = perf_event_buffer_size (tinfo); | |
969c39fb | 523 | data_tail = tinfo->data_head; |
7c97f91e MM |
524 | |
525 | /* We may need to retry reading the trace. See below. */ | |
526 | while (retries--) | |
527 | { | |
528 | data_head = header->data_head; | |
529 | ||
ed9edfb5 | 530 | /* Delete any leftover trace from the previous iteration. */ |
969c39fb | 531 | VEC_free (btrace_block_s, *btrace); |
ed9edfb5 | 532 | |
969c39fb | 533 | if (type == BTRACE_READ_DELTA) |
7c97f91e | 534 | { |
969c39fb MM |
535 | /* Determine the number of bytes to read and check for buffer |
536 | overflows. */ | |
537 | ||
538 | /* Check for data head overflows. We might be able to recover from | |
539 | those but they are very unlikely and it's not really worth the | |
540 | effort, I think. */ | |
541 | if (data_head < data_tail) | |
542 | return BTRACE_ERR_OVERFLOW; | |
543 | ||
544 | /* If the buffer is smaller than the trace delta, we overflowed. */ | |
545 | size = data_head - data_tail; | |
546 | if (buffer_size < size) | |
547 | return BTRACE_ERR_OVERFLOW; | |
548 | } | |
549 | else | |
550 | { | |
551 | /* Read the entire buffer. */ | |
552 | size = buffer_size; | |
7c97f91e | 553 | |
969c39fb MM |
554 | /* Adjust the size if the buffer has not overflowed, yet. */ |
555 | if (data_head < size) | |
556 | size = data_head; | |
7c97f91e MM |
557 | } |
558 | ||
969c39fb MM |
559 | /* Data_head keeps growing; the buffer itself is circular. */ |
560 | begin = perf_event_buffer_begin (tinfo); | |
561 | start = begin + data_head % buffer_size; | |
562 | ||
563 | if (data_head <= buffer_size) | |
564 | end = start; | |
565 | else | |
566 | end = perf_event_buffer_end (tinfo); | |
567 | ||
568 | *btrace = perf_event_read_bts (tinfo, begin, end, start, size); | |
569 | ||
7c97f91e MM |
570 | /* The stopping thread notifies its ptracer before it is scheduled out. |
571 | On multi-core systems, the debugger might therefore run while the | |
572 | kernel might be writing the last branch trace records. | |
573 | ||
574 | Let's check whether the data head moved while we read the trace. */ | |
575 | if (data_head == header->data_head) | |
576 | break; | |
577 | } | |
578 | ||
579 | tinfo->data_head = data_head; | |
580 | ||
969c39fb MM |
581 | /* Prune the incomplete last block (i.e. the first one of inferior execution) |
582 | if we're not doing a delta read. There is no way of filling in its zeroed | |
583 | BEGIN element. */ | |
584 | if (!VEC_empty (btrace_block_s, *btrace) && type != BTRACE_READ_DELTA) | |
585 | VEC_pop (btrace_block_s, *btrace); | |
586 | ||
587 | return BTRACE_ERR_NONE; | |
7c97f91e MM |
588 | } |
589 | ||
590 | #else /* !HAVE_LINUX_PERF_EVENT_H */ | |
591 | ||
592 | /* See linux-btrace.h. */ | |
593 | ||
594 | int | |
46917d26 | 595 | linux_supports_btrace (struct target_ops *ops) |
7c97f91e MM |
596 | { |
597 | return 0; | |
598 | } | |
599 | ||
600 | /* See linux-btrace.h. */ | |
601 | ||
602 | struct btrace_target_info * | |
603 | linux_enable_btrace (ptid_t ptid) | |
604 | { | |
605 | return NULL; | |
606 | } | |
607 | ||
608 | /* See linux-btrace.h. */ | |
609 | ||
969c39fb | 610 | enum btrace_error |
7c97f91e MM |
611 | linux_disable_btrace (struct btrace_target_info *tinfo) |
612 | { | |
969c39fb | 613 | return BTRACE_ERR_NOT_SUPPORTED; |
7c97f91e MM |
614 | } |
615 | ||
616 | /* See linux-btrace.h. */ | |
617 | ||
969c39fb MM |
618 | enum btrace_error |
619 | linux_read_btrace (VEC (btrace_block_s) **btrace, | |
620 | struct btrace_target_info *tinfo, | |
7c97f91e MM |
621 | enum btrace_read_type type) |
622 | { | |
969c39fb | 623 | return BTRACE_ERR_NOT_SUPPORTED; |
7c97f91e MM |
624 | } |
625 | ||
626 | #endif /* !HAVE_LINUX_PERF_EVENT_H */ |