| 1 | /* Linux-dependent part of branch trace support for GDB, and GDBserver. |
| 2 | |
| 3 | Copyright (C) 2013-2016 Free Software Foundation, Inc. |
| 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 | #include "common-defs.h" |
| 23 | #include "linux-btrace.h" |
| 24 | #include "common-regcache.h" |
| 25 | #include "gdb_wait.h" |
| 26 | #include "x86-cpuid.h" |
| 27 | #include "filestuff.h" |
| 28 | |
| 29 | #include <inttypes.h> |
| 30 | |
| 31 | #ifdef HAVE_SYS_SYSCALL_H |
| 32 | #include <sys/syscall.h> |
| 33 | #endif |
| 34 | |
| 35 | #if HAVE_LINUX_PERF_EVENT_H && defined(SYS_perf_event_open) |
| 36 | #include <unistd.h> |
| 37 | #include <sys/mman.h> |
| 38 | #include <sys/user.h> |
| 39 | #include "nat/gdb_ptrace.h" |
| 40 | #include <sys/types.h> |
| 41 | #include <signal.h> |
| 42 | |
| 43 | /* A branch trace record in perf_event. */ |
| 44 | struct perf_event_bts |
| 45 | { |
| 46 | /* The linear address of the branch source. */ |
| 47 | uint64_t from; |
| 48 | |
| 49 | /* The linear address of the branch destination. */ |
| 50 | uint64_t to; |
| 51 | }; |
| 52 | |
| 53 | /* A perf_event branch trace sample. */ |
| 54 | struct perf_event_sample |
| 55 | { |
| 56 | /* The perf_event sample header. */ |
| 57 | struct perf_event_header header; |
| 58 | |
| 59 | /* The perf_event branch tracing payload. */ |
| 60 | struct perf_event_bts bts; |
| 61 | }; |
| 62 | |
| 63 | /* Identify the cpu we're running on. */ |
| 64 | static struct btrace_cpu |
| 65 | btrace_this_cpu (void) |
| 66 | { |
| 67 | struct btrace_cpu cpu; |
| 68 | unsigned int eax, ebx, ecx, edx; |
| 69 | int ok; |
| 70 | |
| 71 | memset (&cpu, 0, sizeof (cpu)); |
| 72 | |
| 73 | ok = x86_cpuid (0, &eax, &ebx, &ecx, &edx); |
| 74 | if (ok != 0) |
| 75 | { |
| 76 | if (ebx == signature_INTEL_ebx && ecx == signature_INTEL_ecx |
| 77 | && edx == signature_INTEL_edx) |
| 78 | { |
| 79 | unsigned int cpuid, ignore; |
| 80 | |
| 81 | ok = x86_cpuid (1, &cpuid, &ignore, &ignore, &ignore); |
| 82 | if (ok != 0) |
| 83 | { |
| 84 | cpu.vendor = CV_INTEL; |
| 85 | |
| 86 | cpu.family = (cpuid >> 8) & 0xf; |
| 87 | cpu.model = (cpuid >> 4) & 0xf; |
| 88 | |
| 89 | if (cpu.family == 0x6) |
| 90 | cpu.model += (cpuid >> 12) & 0xf0; |
| 91 | } |
| 92 | } |
| 93 | } |
| 94 | |
| 95 | return cpu; |
| 96 | } |
| 97 | |
| 98 | /* Return non-zero if there is new data in PEVENT; zero otherwise. */ |
| 99 | |
| 100 | static int |
| 101 | perf_event_new_data (const struct perf_event_buffer *pev) |
| 102 | { |
| 103 | return *pev->data_head != pev->last_head; |
| 104 | } |
| 105 | |
| 106 | /* Copy the last SIZE bytes from PEV ending at DATA_HEAD and return a pointer |
| 107 | to the memory holding the copy. |
| 108 | The caller is responsible for freeing the memory. */ |
| 109 | |
| 110 | static gdb_byte * |
| 111 | perf_event_read (const struct perf_event_buffer *pev, __u64 data_head, |
| 112 | size_t size) |
| 113 | { |
| 114 | const gdb_byte *begin, *end, *start, *stop; |
| 115 | gdb_byte *buffer; |
| 116 | size_t buffer_size; |
| 117 | __u64 data_tail; |
| 118 | |
| 119 | if (size == 0) |
| 120 | return NULL; |
| 121 | |
| 122 | /* We should never ask for more data than the buffer can hold. */ |
| 123 | buffer_size = pev->size; |
| 124 | gdb_assert (size <= buffer_size); |
| 125 | |
| 126 | /* If we ask for more data than we seem to have, we wrap around and read |
| 127 | data from the end of the buffer. This is already handled by the % |
| 128 | BUFFER_SIZE operation, below. Here, we just need to make sure that we |
| 129 | don't underflow. |
| 130 | |
| 131 | Note that this is perfectly OK for perf event buffers where data_head |
| 132 | doesn'grow indefinitely and instead wraps around to remain within the |
| 133 | buffer's boundaries. */ |
| 134 | if (data_head < size) |
| 135 | data_head += buffer_size; |
| 136 | |
| 137 | gdb_assert (size <= data_head); |
| 138 | data_tail = data_head - size; |
| 139 | |
| 140 | begin = pev->mem; |
| 141 | start = begin + data_tail % buffer_size; |
| 142 | stop = begin + data_head % buffer_size; |
| 143 | |
| 144 | buffer = (gdb_byte *) xmalloc (size); |
| 145 | |
| 146 | if (start < stop) |
| 147 | memcpy (buffer, start, stop - start); |
| 148 | else |
| 149 | { |
| 150 | end = begin + buffer_size; |
| 151 | |
| 152 | memcpy (buffer, start, end - start); |
| 153 | memcpy (buffer + (end - start), begin, stop - begin); |
| 154 | } |
| 155 | |
| 156 | return buffer; |
| 157 | } |
| 158 | |
| 159 | /* Copy the perf event buffer data from PEV. |
| 160 | Store a pointer to the copy into DATA and its size in SIZE. */ |
| 161 | |
| 162 | static void |
| 163 | perf_event_read_all (struct perf_event_buffer *pev, gdb_byte **data, |
| 164 | size_t *psize) |
| 165 | { |
| 166 | size_t size; |
| 167 | __u64 data_head; |
| 168 | |
| 169 | data_head = *pev->data_head; |
| 170 | size = pev->size; |
| 171 | |
| 172 | *data = perf_event_read (pev, data_head, size); |
| 173 | *psize = size; |
| 174 | |
| 175 | pev->last_head = data_head; |
| 176 | } |
| 177 | |
| 178 | /* Determine the event type. |
| 179 | Returns zero on success and fills in TYPE; returns -1 otherwise. */ |
| 180 | |
| 181 | static int |
| 182 | perf_event_pt_event_type (int *type) |
| 183 | { |
| 184 | FILE *file; |
| 185 | int found; |
| 186 | |
| 187 | file = fopen ("/sys/bus/event_source/devices/intel_pt/type", "r"); |
| 188 | if (file == NULL) |
| 189 | return -1; |
| 190 | |
| 191 | found = fscanf (file, "%d", type); |
| 192 | |
| 193 | fclose (file); |
| 194 | |
| 195 | if (found == 1) |
| 196 | return 0; |
| 197 | return -1; |
| 198 | } |
| 199 | |
| 200 | /* Try to determine the start address of the Linux kernel. */ |
| 201 | |
| 202 | static uint64_t |
| 203 | linux_determine_kernel_start (void) |
| 204 | { |
| 205 | static uint64_t kernel_start; |
| 206 | static int cached; |
| 207 | FILE *file; |
| 208 | |
| 209 | if (cached != 0) |
| 210 | return kernel_start; |
| 211 | |
| 212 | cached = 1; |
| 213 | |
| 214 | file = gdb_fopen_cloexec ("/proc/kallsyms", "r"); |
| 215 | if (file == NULL) |
| 216 | return kernel_start; |
| 217 | |
| 218 | while (!feof (file)) |
| 219 | { |
| 220 | char buffer[1024], symbol[8], *line; |
| 221 | uint64_t addr; |
| 222 | int match; |
| 223 | |
| 224 | line = fgets (buffer, sizeof (buffer), file); |
| 225 | if (line == NULL) |
| 226 | break; |
| 227 | |
| 228 | match = sscanf (line, "%" SCNx64 " %*[tT] %7s", &addr, symbol); |
| 229 | if (match != 2) |
| 230 | continue; |
| 231 | |
| 232 | if (strcmp (symbol, "_text") == 0) |
| 233 | { |
| 234 | kernel_start = addr; |
| 235 | break; |
| 236 | } |
| 237 | } |
| 238 | |
| 239 | fclose (file); |
| 240 | |
| 241 | return kernel_start; |
| 242 | } |
| 243 | |
| 244 | /* Check whether an address is in the kernel. */ |
| 245 | |
| 246 | static inline int |
| 247 | perf_event_is_kernel_addr (uint64_t addr) |
| 248 | { |
| 249 | uint64_t kernel_start; |
| 250 | |
| 251 | kernel_start = linux_determine_kernel_start (); |
| 252 | if (kernel_start != 0ull) |
| 253 | return (addr >= kernel_start); |
| 254 | |
| 255 | /* If we don't know the kernel's start address, let's check the most |
| 256 | significant bit. This will work at least for 64-bit kernels. */ |
| 257 | return ((addr & (1ull << 63)) != 0); |
| 258 | } |
| 259 | |
| 260 | /* Check whether a perf event record should be skipped. */ |
| 261 | |
| 262 | static inline int |
| 263 | perf_event_skip_bts_record (const struct perf_event_bts *bts) |
| 264 | { |
| 265 | /* The hardware may report branches from kernel into user space. Branches |
| 266 | from user into kernel space will be suppressed. We filter the former to |
| 267 | provide a consistent branch trace excluding kernel. */ |
| 268 | return perf_event_is_kernel_addr (bts->from); |
| 269 | } |
| 270 | |
| 271 | /* Perform a few consistency checks on a perf event sample record. This is |
| 272 | meant to catch cases when we get out of sync with the perf event stream. */ |
| 273 | |
| 274 | static inline int |
| 275 | perf_event_sample_ok (const struct perf_event_sample *sample) |
| 276 | { |
| 277 | if (sample->header.type != PERF_RECORD_SAMPLE) |
| 278 | return 0; |
| 279 | |
| 280 | if (sample->header.size != sizeof (*sample)) |
| 281 | return 0; |
| 282 | |
| 283 | return 1; |
| 284 | } |
| 285 | |
| 286 | /* Branch trace is collected in a circular buffer [begin; end) as pairs of from |
| 287 | and to addresses (plus a header). |
| 288 | |
| 289 | Start points into that buffer at the next sample position. |
| 290 | We read the collected samples backwards from start. |
| 291 | |
| 292 | While reading the samples, we convert the information into a list of blocks. |
| 293 | For two adjacent samples s1 and s2, we form a block b such that b.begin = |
| 294 | s1.to and b.end = s2.from. |
| 295 | |
| 296 | In case the buffer overflows during sampling, one sample may have its lower |
| 297 | part at the end and its upper part at the beginning of the buffer. */ |
| 298 | |
| 299 | static VEC (btrace_block_s) * |
| 300 | perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin, |
| 301 | const uint8_t *end, const uint8_t *start, size_t size) |
| 302 | { |
| 303 | VEC (btrace_block_s) *btrace = NULL; |
| 304 | struct perf_event_sample sample; |
| 305 | size_t read = 0; |
| 306 | struct btrace_block block = { 0, 0 }; |
| 307 | struct regcache *regcache; |
| 308 | |
| 309 | gdb_assert (begin <= start); |
| 310 | gdb_assert (start <= end); |
| 311 | |
| 312 | /* The first block ends at the current pc. */ |
| 313 | regcache = get_thread_regcache_for_ptid (tinfo->ptid); |
| 314 | block.end = regcache_read_pc (regcache); |
| 315 | |
| 316 | /* The buffer may contain a partial record as its last entry (i.e. when the |
| 317 | buffer size is not a multiple of the sample size). */ |
| 318 | read = sizeof (sample) - 1; |
| 319 | |
| 320 | for (; read < size; read += sizeof (sample)) |
| 321 | { |
| 322 | const struct perf_event_sample *psample; |
| 323 | |
| 324 | /* Find the next perf_event sample in a backwards traversal. */ |
| 325 | start -= sizeof (sample); |
| 326 | |
| 327 | /* If we're still inside the buffer, we're done. */ |
| 328 | if (begin <= start) |
| 329 | psample = (const struct perf_event_sample *) start; |
| 330 | else |
| 331 | { |
| 332 | int missing; |
| 333 | |
| 334 | /* We're to the left of the ring buffer, we will wrap around and |
| 335 | reappear at the very right of the ring buffer. */ |
| 336 | |
| 337 | missing = (begin - start); |
| 338 | start = (end - missing); |
| 339 | |
| 340 | /* If the entire sample is missing, we're done. */ |
| 341 | if (missing == sizeof (sample)) |
| 342 | psample = (const struct perf_event_sample *) start; |
| 343 | else |
| 344 | { |
| 345 | uint8_t *stack; |
| 346 | |
| 347 | /* The sample wrapped around. The lower part is at the end and |
| 348 | the upper part is at the beginning of the buffer. */ |
| 349 | stack = (uint8_t *) &sample; |
| 350 | |
| 351 | /* Copy the two parts so we have a contiguous sample. */ |
| 352 | memcpy (stack, start, missing); |
| 353 | memcpy (stack + missing, begin, sizeof (sample) - missing); |
| 354 | |
| 355 | psample = &sample; |
| 356 | } |
| 357 | } |
| 358 | |
| 359 | if (!perf_event_sample_ok (psample)) |
| 360 | { |
| 361 | warning (_("Branch trace may be incomplete.")); |
| 362 | break; |
| 363 | } |
| 364 | |
| 365 | if (perf_event_skip_bts_record (&psample->bts)) |
| 366 | continue; |
| 367 | |
| 368 | /* We found a valid sample, so we can complete the current block. */ |
| 369 | block.begin = psample->bts.to; |
| 370 | |
| 371 | VEC_safe_push (btrace_block_s, btrace, &block); |
| 372 | |
| 373 | /* Start the next block. */ |
| 374 | block.end = psample->bts.from; |
| 375 | } |
| 376 | |
| 377 | /* Push the last block (i.e. the first one of inferior execution), as well. |
| 378 | We don't know where it ends, but we know where it starts. If we're |
| 379 | reading delta trace, we can fill in the start address later on. |
| 380 | Otherwise we will prune it. */ |
| 381 | block.begin = 0; |
| 382 | VEC_safe_push (btrace_block_s, btrace, &block); |
| 383 | |
| 384 | return btrace; |
| 385 | } |
| 386 | |
| 387 | /* Check whether the kernel supports BTS. */ |
| 388 | |
| 389 | static int |
| 390 | kernel_supports_bts (void) |
| 391 | { |
| 392 | struct perf_event_attr attr; |
| 393 | pid_t child, pid; |
| 394 | int status, file; |
| 395 | |
| 396 | errno = 0; |
| 397 | child = fork (); |
| 398 | switch (child) |
| 399 | { |
| 400 | case -1: |
| 401 | warning (_("test bts: cannot fork: %s."), safe_strerror (errno)); |
| 402 | return 0; |
| 403 | |
| 404 | case 0: |
| 405 | status = ptrace (PTRACE_TRACEME, 0, NULL, NULL); |
| 406 | if (status != 0) |
| 407 | { |
| 408 | warning (_("test bts: cannot PTRACE_TRACEME: %s."), |
| 409 | safe_strerror (errno)); |
| 410 | _exit (1); |
| 411 | } |
| 412 | |
| 413 | status = raise (SIGTRAP); |
| 414 | if (status != 0) |
| 415 | { |
| 416 | warning (_("test bts: cannot raise SIGTRAP: %s."), |
| 417 | safe_strerror (errno)); |
| 418 | _exit (1); |
| 419 | } |
| 420 | |
| 421 | _exit (1); |
| 422 | |
| 423 | default: |
| 424 | pid = waitpid (child, &status, 0); |
| 425 | if (pid != child) |
| 426 | { |
| 427 | warning (_("test bts: bad pid %ld, error: %s."), |
| 428 | (long) pid, safe_strerror (errno)); |
| 429 | return 0; |
| 430 | } |
| 431 | |
| 432 | if (!WIFSTOPPED (status)) |
| 433 | { |
| 434 | warning (_("test bts: expected stop. status: %d."), |
| 435 | status); |
| 436 | return 0; |
| 437 | } |
| 438 | |
| 439 | memset (&attr, 0, sizeof (attr)); |
| 440 | |
| 441 | attr.type = PERF_TYPE_HARDWARE; |
| 442 | attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; |
| 443 | attr.sample_period = 1; |
| 444 | attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; |
| 445 | attr.exclude_kernel = 1; |
| 446 | attr.exclude_hv = 1; |
| 447 | attr.exclude_idle = 1; |
| 448 | |
| 449 | file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0); |
| 450 | if (file >= 0) |
| 451 | close (file); |
| 452 | |
| 453 | kill (child, SIGKILL); |
| 454 | ptrace (PTRACE_KILL, child, NULL, NULL); |
| 455 | |
| 456 | pid = waitpid (child, &status, 0); |
| 457 | if (pid != child) |
| 458 | { |
| 459 | warning (_("test bts: bad pid %ld, error: %s."), |
| 460 | (long) pid, safe_strerror (errno)); |
| 461 | if (!WIFSIGNALED (status)) |
| 462 | warning (_("test bts: expected killed. status: %d."), |
| 463 | status); |
| 464 | } |
| 465 | |
| 466 | return (file >= 0); |
| 467 | } |
| 468 | } |
| 469 | |
| 470 | /* Check whether the kernel supports Intel Processor Trace. */ |
| 471 | |
| 472 | static int |
| 473 | kernel_supports_pt (void) |
| 474 | { |
| 475 | struct perf_event_attr attr; |
| 476 | pid_t child, pid; |
| 477 | int status, file, type; |
| 478 | |
| 479 | errno = 0; |
| 480 | child = fork (); |
| 481 | switch (child) |
| 482 | { |
| 483 | case -1: |
| 484 | warning (_("test pt: cannot fork: %s."), safe_strerror (errno)); |
| 485 | return 0; |
| 486 | |
| 487 | case 0: |
| 488 | status = ptrace (PTRACE_TRACEME, 0, NULL, NULL); |
| 489 | if (status != 0) |
| 490 | { |
| 491 | warning (_("test pt: cannot PTRACE_TRACEME: %s."), |
| 492 | safe_strerror (errno)); |
| 493 | _exit (1); |
| 494 | } |
| 495 | |
| 496 | status = raise (SIGTRAP); |
| 497 | if (status != 0) |
| 498 | { |
| 499 | warning (_("test pt: cannot raise SIGTRAP: %s."), |
| 500 | safe_strerror (errno)); |
| 501 | _exit (1); |
| 502 | } |
| 503 | |
| 504 | _exit (1); |
| 505 | |
| 506 | default: |
| 507 | pid = waitpid (child, &status, 0); |
| 508 | if (pid != child) |
| 509 | { |
| 510 | warning (_("test pt: bad pid %ld, error: %s."), |
| 511 | (long) pid, safe_strerror (errno)); |
| 512 | return 0; |
| 513 | } |
| 514 | |
| 515 | if (!WIFSTOPPED (status)) |
| 516 | { |
| 517 | warning (_("test pt: expected stop. status: %d."), |
| 518 | status); |
| 519 | return 0; |
| 520 | } |
| 521 | |
| 522 | status = perf_event_pt_event_type (&type); |
| 523 | if (status != 0) |
| 524 | file = -1; |
| 525 | else |
| 526 | { |
| 527 | memset (&attr, 0, sizeof (attr)); |
| 528 | |
| 529 | attr.size = sizeof (attr); |
| 530 | attr.type = type; |
| 531 | attr.exclude_kernel = 1; |
| 532 | attr.exclude_hv = 1; |
| 533 | attr.exclude_idle = 1; |
| 534 | |
| 535 | file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0); |
| 536 | if (file >= 0) |
| 537 | close (file); |
| 538 | } |
| 539 | |
| 540 | kill (child, SIGKILL); |
| 541 | ptrace (PTRACE_KILL, child, NULL, NULL); |
| 542 | |
| 543 | pid = waitpid (child, &status, 0); |
| 544 | if (pid != child) |
| 545 | { |
| 546 | warning (_("test pt: bad pid %ld, error: %s."), |
| 547 | (long) pid, safe_strerror (errno)); |
| 548 | if (!WIFSIGNALED (status)) |
| 549 | warning (_("test pt: expected killed. status: %d."), |
| 550 | status); |
| 551 | } |
| 552 | |
| 553 | return (file >= 0); |
| 554 | } |
| 555 | } |
| 556 | |
| 557 | /* Check whether an Intel cpu supports BTS. */ |
| 558 | |
| 559 | static int |
| 560 | intel_supports_bts (const struct btrace_cpu *cpu) |
| 561 | { |
| 562 | switch (cpu->family) |
| 563 | { |
| 564 | case 0x6: |
| 565 | switch (cpu->model) |
| 566 | { |
| 567 | case 0x1a: /* Nehalem */ |
| 568 | case 0x1f: |
| 569 | case 0x1e: |
| 570 | case 0x2e: |
| 571 | case 0x25: /* Westmere */ |
| 572 | case 0x2c: |
| 573 | case 0x2f: |
| 574 | case 0x2a: /* Sandy Bridge */ |
| 575 | case 0x2d: |
| 576 | case 0x3a: /* Ivy Bridge */ |
| 577 | |
| 578 | /* AAJ122: LBR, BTM, or BTS records may have incorrect branch |
| 579 | "from" information afer an EIST transition, T-states, C1E, or |
| 580 | Adaptive Thermal Throttling. */ |
| 581 | return 0; |
| 582 | } |
| 583 | } |
| 584 | |
| 585 | return 1; |
| 586 | } |
| 587 | |
| 588 | /* Check whether the cpu supports BTS. */ |
| 589 | |
| 590 | static int |
| 591 | cpu_supports_bts (void) |
| 592 | { |
| 593 | struct btrace_cpu cpu; |
| 594 | |
| 595 | cpu = btrace_this_cpu (); |
| 596 | switch (cpu.vendor) |
| 597 | { |
| 598 | default: |
| 599 | /* Don't know about others. Let's assume they do. */ |
| 600 | return 1; |
| 601 | |
| 602 | case CV_INTEL: |
| 603 | return intel_supports_bts (&cpu); |
| 604 | } |
| 605 | } |
| 606 | |
| 607 | /* Check whether the linux target supports BTS. */ |
| 608 | |
| 609 | static int |
| 610 | linux_supports_bts (void) |
| 611 | { |
| 612 | static int cached; |
| 613 | |
| 614 | if (cached == 0) |
| 615 | { |
| 616 | if (!kernel_supports_bts ()) |
| 617 | cached = -1; |
| 618 | else if (!cpu_supports_bts ()) |
| 619 | cached = -1; |
| 620 | else |
| 621 | cached = 1; |
| 622 | } |
| 623 | |
| 624 | return cached > 0; |
| 625 | } |
| 626 | |
| 627 | /* Check whether the linux target supports Intel Processor Trace. */ |
| 628 | |
| 629 | static int |
| 630 | linux_supports_pt (void) |
| 631 | { |
| 632 | static int cached; |
| 633 | |
| 634 | if (cached == 0) |
| 635 | { |
| 636 | if (!kernel_supports_pt ()) |
| 637 | cached = -1; |
| 638 | else |
| 639 | cached = 1; |
| 640 | } |
| 641 | |
| 642 | return cached > 0; |
| 643 | } |
| 644 | |
| 645 | /* See linux-btrace.h. */ |
| 646 | |
| 647 | int |
| 648 | linux_supports_btrace (struct target_ops *ops, enum btrace_format format) |
| 649 | { |
| 650 | switch (format) |
| 651 | { |
| 652 | case BTRACE_FORMAT_NONE: |
| 653 | return 0; |
| 654 | |
| 655 | case BTRACE_FORMAT_BTS: |
| 656 | return linux_supports_bts (); |
| 657 | |
| 658 | case BTRACE_FORMAT_PT: |
| 659 | return linux_supports_pt (); |
| 660 | } |
| 661 | |
| 662 | internal_error (__FILE__, __LINE__, _("Unknown branch trace format")); |
| 663 | } |
| 664 | |
| 665 | /* Enable branch tracing in BTS format. */ |
| 666 | |
| 667 | static struct btrace_target_info * |
| 668 | linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf) |
| 669 | { |
| 670 | struct perf_event_mmap_page *header; |
| 671 | struct btrace_target_info *tinfo; |
| 672 | struct btrace_tinfo_bts *bts; |
| 673 | size_t size, pages; |
| 674 | __u64 data_offset; |
| 675 | int pid, pg; |
| 676 | |
| 677 | tinfo = XCNEW (struct btrace_target_info); |
| 678 | tinfo->ptid = ptid; |
| 679 | |
| 680 | tinfo->conf.format = BTRACE_FORMAT_BTS; |
| 681 | bts = &tinfo->variant.bts; |
| 682 | |
| 683 | bts->attr.size = sizeof (bts->attr); |
| 684 | bts->attr.type = PERF_TYPE_HARDWARE; |
| 685 | bts->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS; |
| 686 | bts->attr.sample_period = 1; |
| 687 | |
| 688 | /* We sample from and to address. */ |
| 689 | bts->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR; |
| 690 | |
| 691 | bts->attr.exclude_kernel = 1; |
| 692 | bts->attr.exclude_hv = 1; |
| 693 | bts->attr.exclude_idle = 1; |
| 694 | |
| 695 | pid = ptid_get_lwp (ptid); |
| 696 | if (pid == 0) |
| 697 | pid = ptid_get_pid (ptid); |
| 698 | |
| 699 | errno = 0; |
| 700 | bts->file = syscall (SYS_perf_event_open, &bts->attr, pid, -1, -1, 0); |
| 701 | if (bts->file < 0) |
| 702 | goto err_out; |
| 703 | |
| 704 | /* Convert the requested size in bytes to pages (rounding up). */ |
| 705 | pages = ((size_t) conf->size / PAGE_SIZE |
| 706 | + ((conf->size % PAGE_SIZE) == 0 ? 0 : 1)); |
| 707 | /* We need at least one page. */ |
| 708 | if (pages == 0) |
| 709 | pages = 1; |
| 710 | |
| 711 | /* The buffer size can be requested in powers of two pages. Adjust PAGES |
| 712 | to the next power of two. */ |
| 713 | for (pg = 0; pages != ((size_t) 1 << pg); ++pg) |
| 714 | if ((pages & ((size_t) 1 << pg)) != 0) |
| 715 | pages += ((size_t) 1 << pg); |
| 716 | |
| 717 | /* We try to allocate the requested size. |
| 718 | If that fails, try to get as much as we can. */ |
| 719 | for (; pages > 0; pages >>= 1) |
| 720 | { |
| 721 | size_t length; |
| 722 | __u64 data_size; |
| 723 | |
| 724 | data_size = (__u64) pages * PAGE_SIZE; |
| 725 | |
| 726 | /* Don't ask for more than we can represent in the configuration. */ |
| 727 | if ((__u64) UINT_MAX < data_size) |
| 728 | continue; |
| 729 | |
| 730 | size = (size_t) data_size; |
| 731 | length = size + PAGE_SIZE; |
| 732 | |
| 733 | /* Check for overflows. */ |
| 734 | if ((__u64) length != data_size + PAGE_SIZE) |
| 735 | continue; |
| 736 | |
| 737 | /* The number of pages we request needs to be a power of two. */ |
| 738 | header = ((struct perf_event_mmap_page *) |
| 739 | mmap (NULL, length, PROT_READ, MAP_SHARED, bts->file, 0)); |
| 740 | if (header != MAP_FAILED) |
| 741 | break; |
| 742 | } |
| 743 | |
| 744 | if (pages == 0) |
| 745 | goto err_file; |
| 746 | |
| 747 | data_offset = PAGE_SIZE; |
| 748 | |
| 749 | #if defined (PERF_ATTR_SIZE_VER5) |
| 750 | if (offsetof (struct perf_event_mmap_page, data_size) <= header->size) |
| 751 | { |
| 752 | __u64 data_size; |
| 753 | |
| 754 | data_offset = header->data_offset; |
| 755 | data_size = header->data_size; |
| 756 | |
| 757 | size = (unsigned int) data_size; |
| 758 | |
| 759 | /* Check for overflows. */ |
| 760 | if ((__u64) size != data_size) |
| 761 | { |
| 762 | munmap ((void *) header, size + PAGE_SIZE); |
| 763 | goto err_file; |
| 764 | } |
| 765 | } |
| 766 | #endif /* defined (PERF_ATTR_SIZE_VER5) */ |
| 767 | |
| 768 | bts->header = header; |
| 769 | bts->bts.mem = ((const uint8_t *) header) + data_offset; |
| 770 | bts->bts.size = size; |
| 771 | bts->bts.data_head = &header->data_head; |
| 772 | bts->bts.last_head = 0ull; |
| 773 | |
| 774 | tinfo->conf.bts.size = (unsigned int) size; |
| 775 | return tinfo; |
| 776 | |
| 777 | err_file: |
| 778 | /* We were not able to allocate any buffer. */ |
| 779 | close (bts->file); |
| 780 | |
| 781 | err_out: |
| 782 | xfree (tinfo); |
| 783 | return NULL; |
| 784 | } |
| 785 | |
| 786 | #if defined (PERF_ATTR_SIZE_VER5) |
| 787 | |
| 788 | /* Enable branch tracing in Intel Processor Trace format. */ |
| 789 | |
| 790 | static struct btrace_target_info * |
| 791 | linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) |
| 792 | { |
| 793 | struct perf_event_mmap_page *header; |
| 794 | struct btrace_target_info *tinfo; |
| 795 | struct btrace_tinfo_pt *pt; |
| 796 | size_t pages, size; |
| 797 | int pid, pg, errcode, type; |
| 798 | |
| 799 | if (conf->size == 0) |
| 800 | return NULL; |
| 801 | |
| 802 | errcode = perf_event_pt_event_type (&type); |
| 803 | if (errcode != 0) |
| 804 | return NULL; |
| 805 | |
| 806 | pid = ptid_get_lwp (ptid); |
| 807 | if (pid == 0) |
| 808 | pid = ptid_get_pid (ptid); |
| 809 | |
| 810 | tinfo = XCNEW (struct btrace_target_info); |
| 811 | tinfo->ptid = ptid; |
| 812 | |
| 813 | tinfo->conf.format = BTRACE_FORMAT_PT; |
| 814 | pt = &tinfo->variant.pt; |
| 815 | |
| 816 | pt->attr.size = sizeof (pt->attr); |
| 817 | pt->attr.type = type; |
| 818 | |
| 819 | pt->attr.exclude_kernel = 1; |
| 820 | pt->attr.exclude_hv = 1; |
| 821 | pt->attr.exclude_idle = 1; |
| 822 | |
| 823 | errno = 0; |
| 824 | pt->file = syscall (SYS_perf_event_open, &pt->attr, pid, -1, -1, 0); |
| 825 | if (pt->file < 0) |
| 826 | goto err; |
| 827 | |
| 828 | /* Allocate the configuration page. */ |
| 829 | header = ((struct perf_event_mmap_page *) |
| 830 | mmap (NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, |
| 831 | pt->file, 0)); |
| 832 | if (header == MAP_FAILED) |
| 833 | goto err_file; |
| 834 | |
| 835 | header->aux_offset = header->data_offset + header->data_size; |
| 836 | |
| 837 | /* Convert the requested size in bytes to pages (rounding up). */ |
| 838 | pages = ((size_t) conf->size / PAGE_SIZE |
| 839 | + ((conf->size % PAGE_SIZE) == 0 ? 0 : 1)); |
| 840 | /* We need at least one page. */ |
| 841 | if (pages == 0) |
| 842 | pages = 1; |
| 843 | |
| 844 | /* The buffer size can be requested in powers of two pages. Adjust PAGES |
| 845 | to the next power of two. */ |
| 846 | for (pg = 0; pages != ((size_t) 1 << pg); ++pg) |
| 847 | if ((pages & ((size_t) 1 << pg)) != 0) |
| 848 | pages += ((size_t) 1 << pg); |
| 849 | |
| 850 | /* We try to allocate the requested size. |
| 851 | If that fails, try to get as much as we can. */ |
| 852 | for (; pages > 0; pages >>= 1) |
| 853 | { |
| 854 | size_t length; |
| 855 | __u64 data_size; |
| 856 | |
| 857 | data_size = (__u64) pages * PAGE_SIZE; |
| 858 | |
| 859 | /* Don't ask for more than we can represent in the configuration. */ |
| 860 | if ((__u64) UINT_MAX < data_size) |
| 861 | continue; |
| 862 | |
| 863 | size = (size_t) data_size; |
| 864 | |
| 865 | /* Check for overflows. */ |
| 866 | if ((__u64) size != data_size) |
| 867 | continue; |
| 868 | |
| 869 | header->aux_size = data_size; |
| 870 | length = size; |
| 871 | |
| 872 | pt->pt.mem = ((const uint8_t *) |
| 873 | mmap (NULL, length, PROT_READ, MAP_SHARED, pt->file, |
| 874 | header->aux_offset)); |
| 875 | if (pt->pt.mem != MAP_FAILED) |
| 876 | break; |
| 877 | } |
| 878 | |
| 879 | if (pages == 0) |
| 880 | goto err_conf; |
| 881 | |
| 882 | pt->header = header; |
| 883 | pt->pt.size = size; |
| 884 | pt->pt.data_head = &header->aux_head; |
| 885 | |
| 886 | tinfo->conf.pt.size = (unsigned int) size; |
| 887 | return tinfo; |
| 888 | |
| 889 | err_conf: |
| 890 | munmap((void *) header, PAGE_SIZE); |
| 891 | |
| 892 | err_file: |
| 893 | close (pt->file); |
| 894 | |
| 895 | err: |
| 896 | xfree (tinfo); |
| 897 | return NULL; |
| 898 | } |
| 899 | |
| 900 | #else /* !defined (PERF_ATTR_SIZE_VER5) */ |
| 901 | |
| 902 | static struct btrace_target_info * |
| 903 | linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf) |
| 904 | { |
| 905 | errno = EOPNOTSUPP; |
| 906 | return NULL; |
| 907 | } |
| 908 | |
| 909 | #endif /* !defined (PERF_ATTR_SIZE_VER5) */ |
| 910 | |
| 911 | /* See linux-btrace.h. */ |
| 912 | |
| 913 | struct btrace_target_info * |
| 914 | linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf) |
| 915 | { |
| 916 | struct btrace_target_info *tinfo; |
| 917 | |
| 918 | tinfo = NULL; |
| 919 | switch (conf->format) |
| 920 | { |
| 921 | case BTRACE_FORMAT_NONE: |
| 922 | break; |
| 923 | |
| 924 | case BTRACE_FORMAT_BTS: |
| 925 | tinfo = linux_enable_bts (ptid, &conf->bts); |
| 926 | break; |
| 927 | |
| 928 | case BTRACE_FORMAT_PT: |
| 929 | tinfo = linux_enable_pt (ptid, &conf->pt); |
| 930 | break; |
| 931 | } |
| 932 | |
| 933 | return tinfo; |
| 934 | } |
| 935 | |
| 936 | /* Disable BTS tracing. */ |
| 937 | |
| 938 | static enum btrace_error |
| 939 | linux_disable_bts (struct btrace_tinfo_bts *tinfo) |
| 940 | { |
| 941 | munmap((void *) tinfo->header, tinfo->bts.size + PAGE_SIZE); |
| 942 | close (tinfo->file); |
| 943 | |
| 944 | return BTRACE_ERR_NONE; |
| 945 | } |
| 946 | |
| 947 | /* Disable Intel Processor Trace tracing. */ |
| 948 | |
| 949 | static enum btrace_error |
| 950 | linux_disable_pt (struct btrace_tinfo_pt *tinfo) |
| 951 | { |
| 952 | munmap((void *) tinfo->pt.mem, tinfo->pt.size); |
| 953 | munmap((void *) tinfo->header, PAGE_SIZE); |
| 954 | close (tinfo->file); |
| 955 | |
| 956 | return BTRACE_ERR_NONE; |
| 957 | } |
| 958 | |
| 959 | /* See linux-btrace.h. */ |
| 960 | |
| 961 | enum btrace_error |
| 962 | linux_disable_btrace (struct btrace_target_info *tinfo) |
| 963 | { |
| 964 | enum btrace_error errcode; |
| 965 | |
| 966 | errcode = BTRACE_ERR_NOT_SUPPORTED; |
| 967 | switch (tinfo->conf.format) |
| 968 | { |
| 969 | case BTRACE_FORMAT_NONE: |
| 970 | break; |
| 971 | |
| 972 | case BTRACE_FORMAT_BTS: |
| 973 | errcode = linux_disable_bts (&tinfo->variant.bts); |
| 974 | break; |
| 975 | |
| 976 | case BTRACE_FORMAT_PT: |
| 977 | errcode = linux_disable_pt (&tinfo->variant.pt); |
| 978 | break; |
| 979 | } |
| 980 | |
| 981 | if (errcode == BTRACE_ERR_NONE) |
| 982 | xfree (tinfo); |
| 983 | |
| 984 | return errcode; |
| 985 | } |
| 986 | |
| 987 | /* Read branch trace data in BTS format for the thread given by TINFO into |
| 988 | BTRACE using the TYPE reading method. */ |
| 989 | |
| 990 | static enum btrace_error |
| 991 | linux_read_bts (struct btrace_data_bts *btrace, |
| 992 | struct btrace_target_info *tinfo, |
| 993 | enum btrace_read_type type) |
| 994 | { |
| 995 | struct perf_event_buffer *pevent; |
| 996 | const uint8_t *begin, *end, *start; |
| 997 | size_t buffer_size, size; |
| 998 | __u64 data_head, data_tail; |
| 999 | unsigned int retries = 5; |
| 1000 | |
| 1001 | pevent = &tinfo->variant.bts.bts; |
| 1002 | |
| 1003 | /* For delta reads, we return at least the partial last block containing |
| 1004 | the current PC. */ |
| 1005 | if (type == BTRACE_READ_NEW && !perf_event_new_data (pevent)) |
| 1006 | return BTRACE_ERR_NONE; |
| 1007 | |
| 1008 | buffer_size = pevent->size; |
| 1009 | data_tail = pevent->last_head; |
| 1010 | |
| 1011 | /* We may need to retry reading the trace. See below. */ |
| 1012 | while (retries--) |
| 1013 | { |
| 1014 | data_head = *pevent->data_head; |
| 1015 | |
| 1016 | /* Delete any leftover trace from the previous iteration. */ |
| 1017 | VEC_free (btrace_block_s, btrace->blocks); |
| 1018 | |
| 1019 | if (type == BTRACE_READ_DELTA) |
| 1020 | { |
| 1021 | __u64 data_size; |
| 1022 | |
| 1023 | /* Determine the number of bytes to read and check for buffer |
| 1024 | overflows. */ |
| 1025 | |
| 1026 | /* Check for data head overflows. We might be able to recover from |
| 1027 | those but they are very unlikely and it's not really worth the |
| 1028 | effort, I think. */ |
| 1029 | if (data_head < data_tail) |
| 1030 | return BTRACE_ERR_OVERFLOW; |
| 1031 | |
| 1032 | /* If the buffer is smaller than the trace delta, we overflowed. */ |
| 1033 | data_size = data_head - data_tail; |
| 1034 | if (buffer_size < data_size) |
| 1035 | return BTRACE_ERR_OVERFLOW; |
| 1036 | |
| 1037 | /* DATA_SIZE <= BUFFER_SIZE and therefore fits into a size_t. */ |
| 1038 | size = (size_t) data_size; |
| 1039 | } |
| 1040 | else |
| 1041 | { |
| 1042 | /* Read the entire buffer. */ |
| 1043 | size = buffer_size; |
| 1044 | |
| 1045 | /* Adjust the size if the buffer has not overflowed, yet. */ |
| 1046 | if (data_head < size) |
| 1047 | size = (size_t) data_head; |
| 1048 | } |
| 1049 | |
| 1050 | /* Data_head keeps growing; the buffer itself is circular. */ |
| 1051 | begin = pevent->mem; |
| 1052 | start = begin + data_head % buffer_size; |
| 1053 | |
| 1054 | if (data_head <= buffer_size) |
| 1055 | end = start; |
| 1056 | else |
| 1057 | end = begin + pevent->size; |
| 1058 | |
| 1059 | btrace->blocks = perf_event_read_bts (tinfo, begin, end, start, size); |
| 1060 | |
| 1061 | /* The stopping thread notifies its ptracer before it is scheduled out. |
| 1062 | On multi-core systems, the debugger might therefore run while the |
| 1063 | kernel might be writing the last branch trace records. |
| 1064 | |
| 1065 | Let's check whether the data head moved while we read the trace. */ |
| 1066 | if (data_head == *pevent->data_head) |
| 1067 | break; |
| 1068 | } |
| 1069 | |
| 1070 | pevent->last_head = data_head; |
| 1071 | |
| 1072 | /* Prune the incomplete last block (i.e. the first one of inferior execution) |
| 1073 | if we're not doing a delta read. There is no way of filling in its zeroed |
| 1074 | BEGIN element. */ |
| 1075 | if (!VEC_empty (btrace_block_s, btrace->blocks) |
| 1076 | && type != BTRACE_READ_DELTA) |
| 1077 | VEC_pop (btrace_block_s, btrace->blocks); |
| 1078 | |
| 1079 | return BTRACE_ERR_NONE; |
| 1080 | } |
| 1081 | |
| 1082 | /* Fill in the Intel Processor Trace configuration information. */ |
| 1083 | |
| 1084 | static void |
| 1085 | linux_fill_btrace_pt_config (struct btrace_data_pt_config *conf) |
| 1086 | { |
| 1087 | conf->cpu = btrace_this_cpu (); |
| 1088 | } |
| 1089 | |
| 1090 | /* Read branch trace data in Intel Processor Trace format for the thread |
| 1091 | given by TINFO into BTRACE using the TYPE reading method. */ |
| 1092 | |
| 1093 | static enum btrace_error |
| 1094 | linux_read_pt (struct btrace_data_pt *btrace, |
| 1095 | struct btrace_target_info *tinfo, |
| 1096 | enum btrace_read_type type) |
| 1097 | { |
| 1098 | struct perf_event_buffer *pt; |
| 1099 | |
| 1100 | pt = &tinfo->variant.pt.pt; |
| 1101 | |
| 1102 | linux_fill_btrace_pt_config (&btrace->config); |
| 1103 | |
| 1104 | switch (type) |
| 1105 | { |
| 1106 | case BTRACE_READ_DELTA: |
| 1107 | /* We don't support delta reads. The data head (i.e. aux_head) wraps |
| 1108 | around to stay inside the aux buffer. */ |
| 1109 | return BTRACE_ERR_NOT_SUPPORTED; |
| 1110 | |
| 1111 | case BTRACE_READ_NEW: |
| 1112 | if (!perf_event_new_data (pt)) |
| 1113 | return BTRACE_ERR_NONE; |
| 1114 | |
| 1115 | /* Fall through. */ |
| 1116 | case BTRACE_READ_ALL: |
| 1117 | perf_event_read_all (pt, &btrace->data, &btrace->size); |
| 1118 | return BTRACE_ERR_NONE; |
| 1119 | } |
| 1120 | |
| 1121 | internal_error (__FILE__, __LINE__, _("Unkown btrace read type.")); |
| 1122 | } |
| 1123 | |
| 1124 | /* See linux-btrace.h. */ |
| 1125 | |
| 1126 | enum btrace_error |
| 1127 | linux_read_btrace (struct btrace_data *btrace, |
| 1128 | struct btrace_target_info *tinfo, |
| 1129 | enum btrace_read_type type) |
| 1130 | { |
| 1131 | switch (tinfo->conf.format) |
| 1132 | { |
| 1133 | case BTRACE_FORMAT_NONE: |
| 1134 | return BTRACE_ERR_NOT_SUPPORTED; |
| 1135 | |
| 1136 | case BTRACE_FORMAT_BTS: |
| 1137 | /* We read btrace in BTS format. */ |
| 1138 | btrace->format = BTRACE_FORMAT_BTS; |
| 1139 | btrace->variant.bts.blocks = NULL; |
| 1140 | |
| 1141 | return linux_read_bts (&btrace->variant.bts, tinfo, type); |
| 1142 | |
| 1143 | case BTRACE_FORMAT_PT: |
| 1144 | /* We read btrace in Intel Processor Trace format. */ |
| 1145 | btrace->format = BTRACE_FORMAT_PT; |
| 1146 | btrace->variant.pt.data = NULL; |
| 1147 | btrace->variant.pt.size = 0; |
| 1148 | |
| 1149 | return linux_read_pt (&btrace->variant.pt, tinfo, type); |
| 1150 | } |
| 1151 | |
| 1152 | internal_error (__FILE__, __LINE__, _("Unkown branch trace format.")); |
| 1153 | } |
| 1154 | |
| 1155 | /* See linux-btrace.h. */ |
| 1156 | |
| 1157 | const struct btrace_config * |
| 1158 | linux_btrace_conf (const struct btrace_target_info *tinfo) |
| 1159 | { |
| 1160 | return &tinfo->conf; |
| 1161 | } |
| 1162 | |
| 1163 | #else /* !HAVE_LINUX_PERF_EVENT_H */ |
| 1164 | |
| 1165 | /* See linux-btrace.h. */ |
| 1166 | |
| 1167 | int |
| 1168 | linux_supports_btrace (struct target_ops *ops, enum btrace_format format) |
| 1169 | { |
| 1170 | return 0; |
| 1171 | } |
| 1172 | |
| 1173 | /* See linux-btrace.h. */ |
| 1174 | |
| 1175 | struct btrace_target_info * |
| 1176 | linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf) |
| 1177 | { |
| 1178 | return NULL; |
| 1179 | } |
| 1180 | |
| 1181 | /* See linux-btrace.h. */ |
| 1182 | |
| 1183 | enum btrace_error |
| 1184 | linux_disable_btrace (struct btrace_target_info *tinfo) |
| 1185 | { |
| 1186 | return BTRACE_ERR_NOT_SUPPORTED; |
| 1187 | } |
| 1188 | |
| 1189 | /* See linux-btrace.h. */ |
| 1190 | |
| 1191 | enum btrace_error |
| 1192 | linux_read_btrace (struct btrace_data *btrace, |
| 1193 | struct btrace_target_info *tinfo, |
| 1194 | enum btrace_read_type type) |
| 1195 | { |
| 1196 | return BTRACE_ERR_NOT_SUPPORTED; |
| 1197 | } |
| 1198 | |
| 1199 | /* See linux-btrace.h. */ |
| 1200 | |
| 1201 | const struct btrace_config * |
| 1202 | linux_btrace_conf (const struct btrace_target_info *tinfo) |
| 1203 | { |
| 1204 | return NULL; |
| 1205 | } |
| 1206 | |
| 1207 | #endif /* !HAVE_LINUX_PERF_EVENT_H */ |