Commit | Line | Data |
---|---|---|
71ad0f5e JO |
1 | /* |
2 | * Post mortem Dwarf CFI based unwinding on top of regs and stack dumps. | |
3 | * | |
4 | * Lots of this code have been borrowed or heavily inspired from parts of | |
5 | * the libunwind 0.99 code which are (amongst other contributors I may have | |
6 | * forgotten): | |
7 | * | |
8 | * Copyright (C) 2002-2007 Hewlett-Packard Co | |
9 | * Contributed by David Mosberger-Tang <davidm@hpl.hp.com> | |
10 | * | |
11 | * And the bugs have been added by: | |
12 | * | |
13 | * Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com> | |
14 | * Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com> | |
15 | * | |
16 | */ | |
17 | ||
18 | #include <elf.h> | |
19 | #include <gelf.h> | |
20 | #include <fcntl.h> | |
21 | #include <string.h> | |
22 | #include <unistd.h> | |
23 | #include <sys/mman.h> | |
24 | #include <linux/list.h> | |
25 | #include <libunwind.h> | |
26 | #include <libunwind-ptrace.h> | |
27 | #include "thread.h" | |
28 | #include "session.h" | |
29 | #include "perf_regs.h" | |
30 | #include "unwind.h" | |
99ca4233 | 31 | #include "symbol.h" |
71ad0f5e JO |
32 | #include "util.h" |
33 | ||
34 | extern int | |
35 | UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as, | |
36 | unw_word_t ip, | |
37 | unw_dyn_info_t *di, | |
38 | unw_proc_info_t *pi, | |
39 | int need_unwind_info, void *arg); | |
40 | ||
41 | #define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table) | |
42 | ||
ab255e72 JP |
43 | extern int |
44 | UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug, | |
45 | unw_word_t ip, | |
46 | unw_word_t segbase, | |
47 | const char *obj_name, unw_word_t start, | |
48 | unw_word_t end); | |
49 | ||
50 | #define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame) | |
51 | ||
71ad0f5e JO |
52 | #define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */ |
53 | #define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */ | |
54 | ||
55 | /* Pointer-encoding formats: */ | |
56 | #define DW_EH_PE_omit 0xff | |
57 | #define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */ | |
58 | #define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */ | |
59 | #define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */ | |
60 | #define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */ | |
61 | #define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */ | |
62 | ||
63 | /* Pointer-encoding application: */ | |
64 | #define DW_EH_PE_absptr 0x00 /* absolute value */ | |
65 | #define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */ | |
66 | ||
67 | /* | |
68 | * The following are not documented by LSB v1.3, yet they are used by | |
69 | * GCC, presumably they aren't documented by LSB since they aren't | |
70 | * used on Linux: | |
71 | */ | |
72 | #define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */ | |
73 | #define DW_EH_PE_aligned 0x50 /* aligned pointer */ | |
74 | ||
75 | /* Flags intentionaly not handled, since they're not needed: | |
76 | * #define DW_EH_PE_indirect 0x80 | |
77 | * #define DW_EH_PE_uleb128 0x01 | |
78 | * #define DW_EH_PE_udata2 0x02 | |
79 | * #define DW_EH_PE_sleb128 0x09 | |
80 | * #define DW_EH_PE_sdata2 0x0a | |
81 | * #define DW_EH_PE_textrel 0x20 | |
82 | * #define DW_EH_PE_datarel 0x30 | |
83 | */ | |
84 | ||
85 | struct unwind_info { | |
86 | struct perf_sample *sample; | |
87 | struct machine *machine; | |
88 | struct thread *thread; | |
71ad0f5e JO |
89 | }; |
90 | ||
91 | #define dw_read(ptr, type, end) ({ \ | |
92 | type *__p = (type *) ptr; \ | |
93 | type __v; \ | |
94 | if ((__p + 1) > (type *) end) \ | |
95 | return -EINVAL; \ | |
96 | __v = *__p++; \ | |
97 | ptr = (typeof(ptr)) __p; \ | |
98 | __v; \ | |
99 | }) | |
100 | ||
101 | static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val, | |
102 | u8 encoding) | |
103 | { | |
104 | u8 *cur = *p; | |
105 | *val = 0; | |
106 | ||
107 | switch (encoding) { | |
108 | case DW_EH_PE_omit: | |
109 | *val = 0; | |
110 | goto out; | |
111 | case DW_EH_PE_ptr: | |
112 | *val = dw_read(cur, unsigned long, end); | |
113 | goto out; | |
114 | default: | |
115 | break; | |
116 | } | |
117 | ||
118 | switch (encoding & DW_EH_PE_APPL_MASK) { | |
119 | case DW_EH_PE_absptr: | |
120 | break; | |
121 | case DW_EH_PE_pcrel: | |
122 | *val = (unsigned long) cur; | |
123 | break; | |
124 | default: | |
125 | return -EINVAL; | |
126 | } | |
127 | ||
128 | if ((encoding & 0x07) == 0x00) | |
129 | encoding |= DW_EH_PE_udata4; | |
130 | ||
131 | switch (encoding & DW_EH_PE_FORMAT_MASK) { | |
132 | case DW_EH_PE_sdata4: | |
133 | *val += dw_read(cur, s32, end); | |
134 | break; | |
135 | case DW_EH_PE_udata4: | |
136 | *val += dw_read(cur, u32, end); | |
137 | break; | |
138 | case DW_EH_PE_sdata8: | |
139 | *val += dw_read(cur, s64, end); | |
140 | break; | |
141 | case DW_EH_PE_udata8: | |
142 | *val += dw_read(cur, u64, end); | |
143 | break; | |
144 | default: | |
145 | return -EINVAL; | |
146 | } | |
147 | ||
148 | out: | |
149 | *p = cur; | |
150 | return 0; | |
151 | } | |
152 | ||
153 | #define dw_read_encoded_value(ptr, end, enc) ({ \ | |
154 | u64 __v; \ | |
155 | if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \ | |
156 | return -EINVAL; \ | |
157 | } \ | |
158 | __v; \ | |
159 | }) | |
160 | ||
71ad0f5e JO |
161 | static u64 elf_section_offset(int fd, const char *name) |
162 | { | |
163 | Elf *elf; | |
164 | GElf_Ehdr ehdr; | |
165 | GElf_Shdr shdr; | |
166 | u64 offset = 0; | |
167 | ||
168 | elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); | |
169 | if (elf == NULL) | |
170 | return 0; | |
171 | ||
172 | do { | |
173 | if (gelf_getehdr(elf, &ehdr) == NULL) | |
174 | break; | |
175 | ||
99ca4233 | 176 | if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL)) |
71ad0f5e JO |
177 | break; |
178 | ||
179 | offset = shdr.sh_offset; | |
180 | } while (0); | |
181 | ||
182 | elf_end(elf); | |
183 | return offset; | |
184 | } | |
185 | ||
186 | struct table_entry { | |
187 | u32 start_ip_offset; | |
188 | u32 fde_offset; | |
189 | }; | |
190 | ||
191 | struct eh_frame_hdr { | |
192 | unsigned char version; | |
193 | unsigned char eh_frame_ptr_enc; | |
194 | unsigned char fde_count_enc; | |
195 | unsigned char table_enc; | |
196 | ||
197 | /* | |
198 | * The rest of the header is variable-length and consists of the | |
199 | * following members: | |
200 | * | |
201 | * encoded_t eh_frame_ptr; | |
202 | * encoded_t fde_count; | |
203 | */ | |
204 | ||
205 | /* A single encoded pointer should not be more than 8 bytes. */ | |
206 | u64 enc[2]; | |
207 | ||
208 | /* | |
209 | * struct { | |
210 | * encoded_t start_ip; | |
211 | * encoded_t fde_addr; | |
212 | * } binary_search_table[fde_count]; | |
213 | */ | |
214 | char data[0]; | |
215 | } __packed; | |
216 | ||
217 | static int unwind_spec_ehframe(struct dso *dso, struct machine *machine, | |
218 | u64 offset, u64 *table_data, u64 *segbase, | |
219 | u64 *fde_count) | |
220 | { | |
221 | struct eh_frame_hdr hdr; | |
222 | u8 *enc = (u8 *) &hdr.enc; | |
223 | u8 *end = (u8 *) &hdr.data; | |
224 | ssize_t r; | |
225 | ||
226 | r = dso__data_read_offset(dso, machine, offset, | |
227 | (u8 *) &hdr, sizeof(hdr)); | |
228 | if (r != sizeof(hdr)) | |
229 | return -EINVAL; | |
230 | ||
231 | /* We dont need eh_frame_ptr, just skip it. */ | |
232 | dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc); | |
233 | ||
234 | *fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc); | |
235 | *segbase = offset; | |
236 | *table_data = (enc - (u8 *) &hdr) + offset; | |
237 | return 0; | |
238 | } | |
239 | ||
ab255e72 JP |
240 | static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine, |
241 | u64 *table_data, u64 *segbase, | |
242 | u64 *fde_count) | |
71ad0f5e JO |
243 | { |
244 | int ret = -EINVAL, fd; | |
245 | u64 offset; | |
246 | ||
247 | fd = dso__data_fd(dso, machine); | |
248 | if (fd < 0) | |
249 | return -EINVAL; | |
250 | ||
ab255e72 | 251 | /* Check the .eh_frame section for unwinding info */ |
71ad0f5e JO |
252 | offset = elf_section_offset(fd, ".eh_frame_hdr"); |
253 | close(fd); | |
254 | ||
255 | if (offset) | |
256 | ret = unwind_spec_ehframe(dso, machine, offset, | |
257 | table_data, segbase, | |
258 | fde_count); | |
259 | ||
71ad0f5e JO |
260 | return ret; |
261 | } | |
262 | ||
ab255e72 JP |
263 | #ifndef NO_LIBUNWIND_DEBUG_FRAME |
264 | static int read_unwind_spec_debug_frame(struct dso *dso, | |
265 | struct machine *machine, u64 *offset) | |
266 | { | |
267 | int fd = dso__data_fd(dso, machine); | |
268 | ||
269 | if (fd < 0) | |
270 | return -EINVAL; | |
271 | ||
272 | /* Check the .debug_frame section for unwinding info */ | |
273 | *offset = elf_section_offset(fd, ".debug_frame"); | |
274 | close(fd); | |
275 | ||
276 | if (*offset) | |
277 | return 0; | |
278 | ||
279 | return -EINVAL; | |
280 | } | |
281 | #endif | |
282 | ||
71ad0f5e JO |
283 | static struct map *find_map(unw_word_t ip, struct unwind_info *ui) |
284 | { | |
285 | struct addr_location al; | |
286 | ||
287 | thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER, | |
326f59bf | 288 | MAP__FUNCTION, ip, &al); |
71ad0f5e JO |
289 | return al.map; |
290 | } | |
291 | ||
292 | static int | |
293 | find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi, | |
294 | int need_unwind_info, void *arg) | |
295 | { | |
296 | struct unwind_info *ui = arg; | |
297 | struct map *map; | |
298 | unw_dyn_info_t di; | |
299 | u64 table_data, segbase, fde_count; | |
300 | ||
301 | map = find_map(ip, ui); | |
302 | if (!map || !map->dso) | |
303 | return -EINVAL; | |
304 | ||
305 | pr_debug("unwind: find_proc_info dso %s\n", map->dso->name); | |
306 | ||
ab255e72 JP |
307 | /* Check the .eh_frame section for unwinding info */ |
308 | if (!read_unwind_spec_eh_frame(map->dso, ui->machine, | |
309 | &table_data, &segbase, &fde_count)) { | |
310 | memset(&di, 0, sizeof(di)); | |
311 | di.format = UNW_INFO_FORMAT_REMOTE_TABLE; | |
312 | di.start_ip = map->start; | |
313 | di.end_ip = map->end; | |
314 | di.u.rti.segbase = map->start + segbase; | |
315 | di.u.rti.table_data = map->start + table_data; | |
316 | di.u.rti.table_len = fde_count * sizeof(struct table_entry) | |
317 | / sizeof(unw_word_t); | |
318 | return dwarf_search_unwind_table(as, ip, &di, pi, | |
319 | need_unwind_info, arg); | |
320 | } | |
321 | ||
322 | #ifndef NO_LIBUNWIND_DEBUG_FRAME | |
323 | /* Check the .debug_frame section for unwinding info */ | |
324 | if (!read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) { | |
325 | memset(&di, 0, sizeof(di)); | |
d11416e7 JP |
326 | if (dwarf_find_debug_frame(0, &di, ip, 0, map->dso->name, |
327 | map->start, map->end)) | |
328 | return dwarf_search_unwind_table(as, ip, &di, pi, | |
329 | need_unwind_info, arg); | |
ab255e72 JP |
330 | } |
331 | #endif | |
71ad0f5e | 332 | |
ab255e72 | 333 | return -EINVAL; |
71ad0f5e JO |
334 | } |
335 | ||
1d037ca1 IT |
336 | static int access_fpreg(unw_addr_space_t __maybe_unused as, |
337 | unw_regnum_t __maybe_unused num, | |
338 | unw_fpreg_t __maybe_unused *val, | |
339 | int __maybe_unused __write, | |
340 | void __maybe_unused *arg) | |
71ad0f5e JO |
341 | { |
342 | pr_err("unwind: access_fpreg unsupported\n"); | |
343 | return -UNW_EINVAL; | |
344 | } | |
345 | ||
1d037ca1 IT |
346 | static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as, |
347 | unw_word_t __maybe_unused *dil_addr, | |
348 | void __maybe_unused *arg) | |
71ad0f5e JO |
349 | { |
350 | return -UNW_ENOINFO; | |
351 | } | |
352 | ||
1d037ca1 IT |
353 | static int resume(unw_addr_space_t __maybe_unused as, |
354 | unw_cursor_t __maybe_unused *cu, | |
355 | void __maybe_unused *arg) | |
71ad0f5e JO |
356 | { |
357 | pr_err("unwind: resume unsupported\n"); | |
358 | return -UNW_EINVAL; | |
359 | } | |
360 | ||
361 | static int | |
1d037ca1 IT |
362 | get_proc_name(unw_addr_space_t __maybe_unused as, |
363 | unw_word_t __maybe_unused addr, | |
364 | char __maybe_unused *bufp, size_t __maybe_unused buf_len, | |
365 | unw_word_t __maybe_unused *offp, void __maybe_unused *arg) | |
71ad0f5e JO |
366 | { |
367 | pr_err("unwind: get_proc_name unsupported\n"); | |
368 | return -UNW_EINVAL; | |
369 | } | |
370 | ||
371 | static int access_dso_mem(struct unwind_info *ui, unw_word_t addr, | |
372 | unw_word_t *data) | |
373 | { | |
374 | struct addr_location al; | |
375 | ssize_t size; | |
376 | ||
377 | thread__find_addr_map(ui->thread, ui->machine, PERF_RECORD_MISC_USER, | |
326f59bf | 378 | MAP__FUNCTION, addr, &al); |
71ad0f5e JO |
379 | if (!al.map) { |
380 | pr_debug("unwind: no map for %lx\n", (unsigned long)addr); | |
381 | return -1; | |
382 | } | |
383 | ||
384 | if (!al.map->dso) | |
385 | return -1; | |
386 | ||
387 | size = dso__data_read_addr(al.map->dso, al.map, ui->machine, | |
388 | addr, (u8 *) data, sizeof(*data)); | |
389 | ||
390 | return !(size == sizeof(*data)); | |
391 | } | |
392 | ||
352ea45a | 393 | static int reg_value(unw_word_t *valp, struct regs_dump *regs, int id) |
71ad0f5e JO |
394 | { |
395 | int i, idx = 0; | |
352ea45a | 396 | u64 mask = regs->mask; |
71ad0f5e | 397 | |
352ea45a | 398 | if (!(mask & (1 << id))) |
71ad0f5e JO |
399 | return -EINVAL; |
400 | ||
401 | for (i = 0; i < id; i++) { | |
352ea45a | 402 | if (mask & (1 << i)) |
71ad0f5e JO |
403 | idx++; |
404 | } | |
405 | ||
406 | *valp = regs->regs[idx]; | |
407 | return 0; | |
408 | } | |
409 | ||
1d037ca1 | 410 | static int access_mem(unw_addr_space_t __maybe_unused as, |
71ad0f5e JO |
411 | unw_word_t addr, unw_word_t *valp, |
412 | int __write, void *arg) | |
413 | { | |
414 | struct unwind_info *ui = arg; | |
415 | struct stack_dump *stack = &ui->sample->user_stack; | |
416 | unw_word_t start, end; | |
417 | int offset; | |
418 | int ret; | |
419 | ||
420 | /* Don't support write, probably not needed. */ | |
421 | if (__write || !stack || !ui->sample->user_regs.regs) { | |
422 | *valp = 0; | |
423 | return 0; | |
424 | } | |
425 | ||
352ea45a | 426 | ret = reg_value(&start, &ui->sample->user_regs, PERF_REG_SP); |
71ad0f5e JO |
427 | if (ret) |
428 | return ret; | |
429 | ||
430 | end = start + stack->size; | |
431 | ||
432 | /* Check overflow. */ | |
433 | if (addr + sizeof(unw_word_t) < addr) | |
434 | return -EINVAL; | |
435 | ||
436 | if (addr < start || addr + sizeof(unw_word_t) >= end) { | |
437 | ret = access_dso_mem(ui, addr, valp); | |
438 | if (ret) { | |
439 | pr_debug("unwind: access_mem %p not inside range %p-%p\n", | |
440 | (void *)addr, (void *)start, (void *)end); | |
441 | *valp = 0; | |
442 | return ret; | |
443 | } | |
444 | return 0; | |
445 | } | |
446 | ||
447 | offset = addr - start; | |
448 | *valp = *(unw_word_t *)&stack->data[offset]; | |
449 | pr_debug("unwind: access_mem addr %p, val %lx, offset %d\n", | |
450 | (void *)addr, (unsigned long)*valp, offset); | |
451 | return 0; | |
452 | } | |
453 | ||
1d037ca1 | 454 | static int access_reg(unw_addr_space_t __maybe_unused as, |
71ad0f5e JO |
455 | unw_regnum_t regnum, unw_word_t *valp, |
456 | int __write, void *arg) | |
457 | { | |
458 | struct unwind_info *ui = arg; | |
459 | int id, ret; | |
460 | ||
461 | /* Don't support write, I suspect we don't need it. */ | |
462 | if (__write) { | |
463 | pr_err("unwind: access_reg w %d\n", regnum); | |
464 | return 0; | |
465 | } | |
466 | ||
467 | if (!ui->sample->user_regs.regs) { | |
468 | *valp = 0; | |
469 | return 0; | |
470 | } | |
471 | ||
472 | id = unwind__arch_reg_id(regnum); | |
473 | if (id < 0) | |
474 | return -EINVAL; | |
475 | ||
352ea45a | 476 | ret = reg_value(valp, &ui->sample->user_regs, id); |
71ad0f5e JO |
477 | if (ret) { |
478 | pr_err("unwind: can't read reg %d\n", regnum); | |
479 | return ret; | |
480 | } | |
481 | ||
482 | pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp); | |
483 | return 0; | |
484 | } | |
485 | ||
1d037ca1 IT |
486 | static void put_unwind_info(unw_addr_space_t __maybe_unused as, |
487 | unw_proc_info_t *pi __maybe_unused, | |
488 | void *arg __maybe_unused) | |
71ad0f5e JO |
489 | { |
490 | pr_debug("unwind: put_unwind_info called\n"); | |
491 | } | |
492 | ||
493 | static int entry(u64 ip, struct thread *thread, struct machine *machine, | |
494 | unwind_entry_cb_t cb, void *arg) | |
495 | { | |
496 | struct unwind_entry e; | |
497 | struct addr_location al; | |
498 | ||
499 | thread__find_addr_location(thread, machine, | |
500 | PERF_RECORD_MISC_USER, | |
61710bde | 501 | MAP__FUNCTION, ip, &al); |
71ad0f5e JO |
502 | |
503 | e.ip = ip; | |
504 | e.map = al.map; | |
505 | e.sym = al.sym; | |
506 | ||
507 | pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n", | |
508 | al.sym ? al.sym->name : "''", | |
509 | ip, | |
510 | al.map ? al.map->map_ip(al.map, ip) : (u64) 0); | |
511 | ||
512 | return cb(&e, arg); | |
513 | } | |
514 | ||
515 | static void display_error(int err) | |
516 | { | |
517 | switch (err) { | |
518 | case UNW_EINVAL: | |
519 | pr_err("unwind: Only supports local.\n"); | |
520 | break; | |
521 | case UNW_EUNSPEC: | |
522 | pr_err("unwind: Unspecified error.\n"); | |
523 | break; | |
524 | case UNW_EBADREG: | |
525 | pr_err("unwind: Register unavailable.\n"); | |
526 | break; | |
527 | default: | |
528 | break; | |
529 | } | |
530 | } | |
531 | ||
532 | static unw_accessors_t accessors = { | |
533 | .find_proc_info = find_proc_info, | |
534 | .put_unwind_info = put_unwind_info, | |
535 | .get_dyn_info_list_addr = get_dyn_info_list_addr, | |
536 | .access_mem = access_mem, | |
537 | .access_reg = access_reg, | |
538 | .access_fpreg = access_fpreg, | |
539 | .resume = resume, | |
540 | .get_proc_name = get_proc_name, | |
541 | }; | |
542 | ||
543 | static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb, | |
37676af1 | 544 | void *arg, int max_stack) |
71ad0f5e JO |
545 | { |
546 | unw_addr_space_t addr_space; | |
547 | unw_cursor_t c; | |
548 | int ret; | |
549 | ||
550 | addr_space = unw_create_addr_space(&accessors, 0); | |
551 | if (!addr_space) { | |
552 | pr_err("unwind: Can't create unwind address space.\n"); | |
553 | return -ENOMEM; | |
554 | } | |
555 | ||
556 | ret = unw_init_remote(&c, addr_space, ui); | |
557 | if (ret) | |
558 | display_error(ret); | |
559 | ||
37676af1 | 560 | while (!ret && (unw_step(&c) > 0) && max_stack--) { |
71ad0f5e JO |
561 | unw_word_t ip; |
562 | ||
563 | unw_get_reg(&c, UNW_REG_IP, &ip); | |
1cf0382a | 564 | ret = ip ? entry(ip, ui->thread, ui->machine, cb, arg) : 0; |
71ad0f5e JO |
565 | } |
566 | ||
567 | unw_destroy_addr_space(addr_space); | |
568 | return ret; | |
569 | } | |
570 | ||
571 | int unwind__get_entries(unwind_entry_cb_t cb, void *arg, | |
572 | struct machine *machine, struct thread *thread, | |
352ea45a | 573 | struct perf_sample *data, int max_stack) |
71ad0f5e JO |
574 | { |
575 | unw_word_t ip; | |
576 | struct unwind_info ui = { | |
577 | .sample = data, | |
71ad0f5e JO |
578 | .thread = thread, |
579 | .machine = machine, | |
580 | }; | |
581 | int ret; | |
582 | ||
583 | if (!data->user_regs.regs) | |
584 | return -EINVAL; | |
585 | ||
352ea45a | 586 | ret = reg_value(&ip, &data->user_regs, PERF_REG_IP); |
71ad0f5e JO |
587 | if (ret) |
588 | return ret; | |
589 | ||
590 | ret = entry(ip, thread, machine, cb, arg); | |
591 | if (ret) | |
592 | return -ENOMEM; | |
593 | ||
b42dc32d | 594 | return --max_stack > 0 ? get_entries(&ui, cb, arg, max_stack) : 0; |
71ad0f5e | 595 | } |