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19#include <elf.h>
20#include <errno.h>
21#include <gelf.h>
22#include <fcntl.h>
23#include <inttypes.h>
24#include <string.h>
25#include <unistd.h>
26#include <sys/mman.h>
27#include <linux/list.h>
28#include <linux/zalloc.h>
29#ifndef REMOTE_UNWIND_LIBUNWIND
30#include <libunwind.h>
31#include <libunwind-ptrace.h>
32#endif
33#include "callchain.h"
34#include "thread.h"
35#include "session.h"
36#include "perf_regs.h"
37#include "unwind.h"
38#include "map.h"
39#include "symbol.h"
40#include "util.h"
41#include "debug.h"
42#include "asm/bug.h"
43#include "dso.h"
44
45extern int
46UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as,
47 unw_word_t ip,
48 unw_dyn_info_t *di,
49 unw_proc_info_t *pi,
50 int need_unwind_info, void *arg);
51
52#define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
53
54extern int
55UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug,
56 unw_word_t ip,
57 unw_word_t segbase,
58 const char *obj_name, unw_word_t start,
59 unw_word_t end);
60
61#define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
62
63#define DW_EH_PE_FORMAT_MASK 0x0f
64#define DW_EH_PE_APPL_MASK 0x70
65
66
67#define DW_EH_PE_omit 0xff
68#define DW_EH_PE_ptr 0x00
69#define DW_EH_PE_udata4 0x03
70#define DW_EH_PE_udata8 0x04
71#define DW_EH_PE_sdata4 0x0b
72#define DW_EH_PE_sdata8 0x0c
73
74
75#define DW_EH_PE_absptr 0x00
76#define DW_EH_PE_pcrel 0x10
77
78
79
80
81
82
83#define DW_EH_PE_funcrel 0x40
84#define DW_EH_PE_aligned 0x50
85
86
87
88
89
90
91
92
93
94
95
96struct unwind_info {
97 struct perf_sample *sample;
98 struct machine *machine;
99 struct thread *thread;
100};
101
102#define dw_read(ptr, type, end) ({ \
103 type *__p = (type *) ptr; \
104 type __v; \
105 if ((__p + 1) > (type *) end) \
106 return -EINVAL; \
107 __v = *__p++; \
108 ptr = (typeof(ptr)) __p; \
109 __v; \
110 })
111
112static int __dw_read_encoded_value(u8 **p, u8 *end, u64 *val,
113 u8 encoding)
114{
115 u8 *cur = *p;
116 *val = 0;
117
118 switch (encoding) {
119 case DW_EH_PE_omit:
120 *val = 0;
121 goto out;
122 case DW_EH_PE_ptr:
123 *val = dw_read(cur, unsigned long, end);
124 goto out;
125 default:
126 break;
127 }
128
129 switch (encoding & DW_EH_PE_APPL_MASK) {
130 case DW_EH_PE_absptr:
131 break;
132 case DW_EH_PE_pcrel:
133 *val = (unsigned long) cur;
134 break;
135 default:
136 return -EINVAL;
137 }
138
139 if ((encoding & 0x07) == 0x00)
140 encoding |= DW_EH_PE_udata4;
141
142 switch (encoding & DW_EH_PE_FORMAT_MASK) {
143 case DW_EH_PE_sdata4:
144 *val += dw_read(cur, s32, end);
145 break;
146 case DW_EH_PE_udata4:
147 *val += dw_read(cur, u32, end);
148 break;
149 case DW_EH_PE_sdata8:
150 *val += dw_read(cur, s64, end);
151 break;
152 case DW_EH_PE_udata8:
153 *val += dw_read(cur, u64, end);
154 break;
155 default:
156 return -EINVAL;
157 }
158
159 out:
160 *p = cur;
161 return 0;
162}
163
164#define dw_read_encoded_value(ptr, end, enc) ({ \
165 u64 __v; \
166 if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
167 return -EINVAL; \
168 } \
169 __v; \
170 })
171
172static u64 elf_section_offset(int fd, const char *name)
173{
174 Elf *elf;
175 GElf_Ehdr ehdr;
176 GElf_Shdr shdr;
177 u64 offset = 0;
178
179 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
180 if (elf == NULL)
181 return 0;
182
183 do {
184 if (gelf_getehdr(elf, &ehdr) == NULL)
185 break;
186
187 if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL))
188 break;
189
190 offset = shdr.sh_offset;
191 } while (0);
192
193 elf_end(elf);
194 return offset;
195}
196
197#ifndef NO_LIBUNWIND_DEBUG_FRAME
198static int elf_is_exec(int fd, const char *name)
199{
200 Elf *elf;
201 GElf_Ehdr ehdr;
202 int retval = 0;
203
204 elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
205 if (elf == NULL)
206 return 0;
207 if (gelf_getehdr(elf, &ehdr) == NULL)
208 goto out;
209
210 retval = (ehdr.e_type == ET_EXEC);
211
212out:
213 elf_end(elf);
214 pr_debug("unwind: elf_is_exec(%s): %d\n", name, retval);
215 return retval;
216}
217#endif
218
219struct table_entry {
220 u32 start_ip_offset;
221 u32 fde_offset;
222};
223
224struct eh_frame_hdr {
225 unsigned char version;
226 unsigned char eh_frame_ptr_enc;
227 unsigned char fde_count_enc;
228 unsigned char table_enc;
229
230
231
232
233
234
235
236
237
238
239 u64 enc[2];
240
241
242
243
244
245
246
247 char data[0];
248} __packed;
249
250static int unwind_spec_ehframe(struct dso *dso, struct machine *machine,
251 u64 offset, u64 *table_data, u64 *segbase,
252 u64 *fde_count)
253{
254 struct eh_frame_hdr hdr;
255 u8 *enc = (u8 *) &hdr.enc;
256 u8 *end = (u8 *) &hdr.data;
257 ssize_t r;
258
259 r = dso__data_read_offset(dso, machine, offset,
260 (u8 *) &hdr, sizeof(hdr));
261 if (r != sizeof(hdr))
262 return -EINVAL;
263
264
265 dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc);
266
267 *fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc);
268 *segbase = offset;
269 *table_data = (enc - (u8 *) &hdr) + offset;
270 return 0;
271}
272
273static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine,
274 u64 *table_data, u64 *segbase,
275 u64 *fde_count)
276{
277 int ret = -EINVAL, fd;
278 u64 offset = dso->data.eh_frame_hdr_offset;
279
280 if (offset == 0) {
281 fd = dso__data_get_fd(dso, machine);
282 if (fd < 0)
283 return -EINVAL;
284
285
286 offset = elf_section_offset(fd, ".eh_frame_hdr");
287 dso->data.eh_frame_hdr_offset = offset;
288 dso__data_put_fd(dso);
289 }
290
291 if (offset)
292 ret = unwind_spec_ehframe(dso, machine, offset,
293 table_data, segbase,
294 fde_count);
295
296 return ret;
297}
298
299#ifndef NO_LIBUNWIND_DEBUG_FRAME
300static int read_unwind_spec_debug_frame(struct dso *dso,
301 struct machine *machine, u64 *offset)
302{
303 int fd;
304 u64 ofs = dso->data.debug_frame_offset;
305
306
307
308
309
310
311
312 if (ofs == 0) {
313 fd = dso__data_get_fd(dso, machine);
314 if (fd >= 0) {
315 ofs = elf_section_offset(fd, ".debug_frame");
316 dso__data_put_fd(dso);
317 }
318
319 if (ofs <= 0) {
320 fd = open(dso->symsrc_filename, O_RDONLY);
321 if (fd >= 0) {
322 ofs = elf_section_offset(fd, ".debug_frame");
323 close(fd);
324 }
325 }
326
327 if (ofs <= 0) {
328 char *debuglink = malloc(PATH_MAX);
329 int ret = 0;
330
331 ret = dso__read_binary_type_filename(
332 dso, DSO_BINARY_TYPE__DEBUGLINK,
333 machine->root_dir, debuglink, PATH_MAX);
334 if (!ret) {
335 fd = open(debuglink, O_RDONLY);
336 if (fd >= 0) {
337 ofs = elf_section_offset(fd,
338 ".debug_frame");
339 close(fd);
340 }
341 }
342 if (ofs > 0) {
343 if (dso->symsrc_filename != NULL) {
344 pr_warning(
345 "%s: overwrite symsrc(%s,%s)\n",
346 __func__,
347 dso->symsrc_filename,
348 debuglink);
349 zfree(&dso->symsrc_filename);
350 }
351 dso->symsrc_filename = debuglink;
352 } else {
353 free(debuglink);
354 }
355 }
356
357 dso->data.debug_frame_offset = ofs;
358 }
359
360 *offset = ofs;
361 if (*offset)
362 return 0;
363
364 return -EINVAL;
365}
366#endif
367
368static struct map *find_map(unw_word_t ip, struct unwind_info *ui)
369{
370 struct addr_location al;
371 return thread__find_map(ui->thread, PERF_RECORD_MISC_USER, ip, &al);
372}
373
374static int
375find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi,
376 int need_unwind_info, void *arg)
377{
378 struct unwind_info *ui = arg;
379 struct map *map;
380 unw_dyn_info_t di;
381 u64 table_data, segbase, fde_count;
382 int ret = -EINVAL;
383
384 map = find_map(ip, ui);
385 if (!map || !map->dso)
386 return -EINVAL;
387
388 pr_debug("unwind: find_proc_info dso %s\n", map->dso->name);
389
390
391 if (!read_unwind_spec_eh_frame(map->dso, ui->machine,
392 &table_data, &segbase, &fde_count)) {
393 memset(&di, 0, sizeof(di));
394 di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
395 di.start_ip = map->start;
396 di.end_ip = map->end;
397 di.u.rti.segbase = map->start + segbase - map->pgoff;
398 di.u.rti.table_data = map->start + table_data - map->pgoff;
399 di.u.rti.table_len = fde_count * sizeof(struct table_entry)
400 / sizeof(unw_word_t);
401 ret = dwarf_search_unwind_table(as, ip, &di, pi,
402 need_unwind_info, arg);
403 }
404
405#ifndef NO_LIBUNWIND_DEBUG_FRAME
406
407 if (ret < 0 &&
408 !read_unwind_spec_debug_frame(map->dso, ui->machine, &segbase)) {
409 int fd = dso__data_get_fd(map->dso, ui->machine);
410 int is_exec = elf_is_exec(fd, map->dso->name);
411 unw_word_t base = is_exec ? 0 : map->start;
412 const char *symfile;
413
414 if (fd >= 0)
415 dso__data_put_fd(map->dso);
416
417 symfile = map->dso->symsrc_filename ?: map->dso->name;
418
419 memset(&di, 0, sizeof(di));
420 if (dwarf_find_debug_frame(0, &di, ip, base, symfile,
421 map->start, map->end))
422 return dwarf_search_unwind_table(as, ip, &di, pi,
423 need_unwind_info, arg);
424 }
425#endif
426
427 return ret;
428}
429
430static int access_fpreg(unw_addr_space_t __maybe_unused as,
431 unw_regnum_t __maybe_unused num,
432 unw_fpreg_t __maybe_unused *val,
433 int __maybe_unused __write,
434 void __maybe_unused *arg)
435{
436 pr_err("unwind: access_fpreg unsupported\n");
437 return -UNW_EINVAL;
438}
439
440static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as,
441 unw_word_t __maybe_unused *dil_addr,
442 void __maybe_unused *arg)
443{
444 return -UNW_ENOINFO;
445}
446
447static int resume(unw_addr_space_t __maybe_unused as,
448 unw_cursor_t __maybe_unused *cu,
449 void __maybe_unused *arg)
450{
451 pr_err("unwind: resume unsupported\n");
452 return -UNW_EINVAL;
453}
454
455static int
456get_proc_name(unw_addr_space_t __maybe_unused as,
457 unw_word_t __maybe_unused addr,
458 char __maybe_unused *bufp, size_t __maybe_unused buf_len,
459 unw_word_t __maybe_unused *offp, void __maybe_unused *arg)
460{
461 pr_err("unwind: get_proc_name unsupported\n");
462 return -UNW_EINVAL;
463}
464
465static int access_dso_mem(struct unwind_info *ui, unw_word_t addr,
466 unw_word_t *data)
467{
468 struct map *map;
469 ssize_t size;
470
471 map = find_map(addr, ui);
472 if (!map) {
473 pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
474 return -1;
475 }
476
477 if (!map->dso)
478 return -1;
479
480 size = dso__data_read_addr(map->dso, map, ui->machine,
481 addr, (u8 *) data, sizeof(*data));
482
483 return !(size == sizeof(*data));
484}
485
486static int access_mem(unw_addr_space_t __maybe_unused as,
487 unw_word_t addr, unw_word_t *valp,
488 int __write, void *arg)
489{
490 struct unwind_info *ui = arg;
491 struct stack_dump *stack = &ui->sample->user_stack;
492 u64 start, end;
493 int offset;
494 int ret;
495
496
497 if (__write || !stack || !ui->sample->user_regs.regs) {
498 *valp = 0;
499 return 0;
500 }
501
502 ret = perf_reg_value(&start, &ui->sample->user_regs,
503 LIBUNWIND__ARCH_REG_SP);
504 if (ret)
505 return ret;
506
507 end = start + stack->size;
508
509
510 if (addr + sizeof(unw_word_t) < addr)
511 return -EINVAL;
512
513 if (addr < start || addr + sizeof(unw_word_t) >= end) {
514 ret = access_dso_mem(ui, addr, valp);
515 if (ret) {
516 pr_debug("unwind: access_mem %p not inside range"
517 " 0x%" PRIx64 "-0x%" PRIx64 "\n",
518 (void *) (uintptr_t) addr, start, end);
519 *valp = 0;
520 return ret;
521 }
522 return 0;
523 }
524
525 offset = addr - start;
526 *valp = *(unw_word_t *)&stack->data[offset];
527 pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
528 (void *) (uintptr_t) addr, (unsigned long)*valp, offset);
529 return 0;
530}
531
532static int access_reg(unw_addr_space_t __maybe_unused as,
533 unw_regnum_t regnum, unw_word_t *valp,
534 int __write, void *arg)
535{
536 struct unwind_info *ui = arg;
537 int id, ret;
538 u64 val;
539
540
541 if (__write) {
542 pr_err("unwind: access_reg w %d\n", regnum);
543 return 0;
544 }
545
546 if (!ui->sample->user_regs.regs) {
547 *valp = 0;
548 return 0;
549 }
550
551 id = LIBUNWIND__ARCH_REG_ID(regnum);
552 if (id < 0)
553 return -EINVAL;
554
555 ret = perf_reg_value(&val, &ui->sample->user_regs, id);
556 if (ret) {
557 pr_err("unwind: can't read reg %d\n", regnum);
558 return ret;
559 }
560
561 *valp = (unw_word_t) val;
562 pr_debug("unwind: reg %d, val %lx\n", regnum, (unsigned long)*valp);
563 return 0;
564}
565
566static void put_unwind_info(unw_addr_space_t __maybe_unused as,
567 unw_proc_info_t *pi __maybe_unused,
568 void *arg __maybe_unused)
569{
570 pr_debug("unwind: put_unwind_info called\n");
571}
572
573static int entry(u64 ip, struct thread *thread,
574 unwind_entry_cb_t cb, void *arg)
575{
576 struct unwind_entry e;
577 struct addr_location al;
578
579 e.sym = thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
580 e.ip = ip;
581 e.map = al.map;
582
583 pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n",
584 al.sym ? al.sym->name : "''",
585 ip,
586 al.map ? al.map->map_ip(al.map, ip) : (u64) 0);
587
588 return cb(&e, arg);
589}
590
591static void display_error(int err)
592{
593 switch (err) {
594 case UNW_EINVAL:
595 pr_err("unwind: Only supports local.\n");
596 break;
597 case UNW_EUNSPEC:
598 pr_err("unwind: Unspecified error.\n");
599 break;
600 case UNW_EBADREG:
601 pr_err("unwind: Register unavailable.\n");
602 break;
603 default:
604 break;
605 }
606}
607
608static unw_accessors_t accessors = {
609 .find_proc_info = find_proc_info,
610 .put_unwind_info = put_unwind_info,
611 .get_dyn_info_list_addr = get_dyn_info_list_addr,
612 .access_mem = access_mem,
613 .access_reg = access_reg,
614 .access_fpreg = access_fpreg,
615 .resume = resume,
616 .get_proc_name = get_proc_name,
617};
618
619static int _unwind__prepare_access(struct thread *thread)
620{
621 thread->addr_space = unw_create_addr_space(&accessors, 0);
622 if (!thread->addr_space) {
623 pr_err("unwind: Can't create unwind address space.\n");
624 return -ENOMEM;
625 }
626
627 unw_set_caching_policy(thread->addr_space, UNW_CACHE_GLOBAL);
628 return 0;
629}
630
631static void _unwind__flush_access(struct thread *thread)
632{
633 unw_flush_cache(thread->addr_space, 0, 0);
634}
635
636static void _unwind__finish_access(struct thread *thread)
637{
638 unw_destroy_addr_space(thread->addr_space);
639}
640
641static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb,
642 void *arg, int max_stack)
643{
644 u64 val;
645 unw_word_t ips[max_stack];
646 unw_addr_space_t addr_space;
647 unw_cursor_t c;
648 int ret, i = 0;
649
650 ret = perf_reg_value(&val, &ui->sample->user_regs,
651 LIBUNWIND__ARCH_REG_IP);
652 if (ret)
653 return ret;
654
655 ips[i++] = (unw_word_t) val;
656
657
658
659
660
661 if (max_stack - 1 > 0) {
662 WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL");
663 addr_space = ui->thread->addr_space;
664
665 if (addr_space == NULL)
666 return -1;
667
668 ret = unw_init_remote(&c, addr_space, ui);
669 if (ret)
670 display_error(ret);
671
672 while (!ret && (unw_step(&c) > 0) && i < max_stack) {
673 unw_get_reg(&c, UNW_REG_IP, &ips[i]);
674
675
676
677
678
679
680
681
682 if (unw_is_signal_frame(&c) <= 0)
683 --ips[i];
684
685 ++i;
686 }
687
688 max_stack = i;
689 }
690
691
692
693
694 for (i = 0; i < max_stack && !ret; i++) {
695 int j = i;
696
697 if (callchain_param.order == ORDER_CALLER)
698 j = max_stack - i - 1;
699 ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0;
700 }
701
702 return ret;
703}
704
705static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg,
706 struct thread *thread,
707 struct perf_sample *data, int max_stack)
708{
709 struct unwind_info ui = {
710 .sample = data,
711 .thread = thread,
712 .machine = thread->mg->machine,
713 };
714
715 if (!data->user_regs.regs)
716 return -EINVAL;
717
718 if (max_stack <= 0)
719 return -EINVAL;
720
721 return get_entries(&ui, cb, arg, max_stack);
722}
723
724static struct unwind_libunwind_ops
725_unwind_libunwind_ops = {
726 .prepare_access = _unwind__prepare_access,
727 .flush_access = _unwind__flush_access,
728 .finish_access = _unwind__finish_access,
729 .get_entries = _unwind__get_entries,
730};
731
732#ifndef REMOTE_UNWIND_LIBUNWIND
733struct unwind_libunwind_ops *
734local_unwind_libunwind_ops = &_unwind_libunwind_ops;
735#endif
736