1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* |
3 | * Post mortem Dwarf CFI based unwinding on top of regs and stack dumps. |
4 | * |
5 | * Lots of this code have been borrowed or heavily inspired from parts of |
6 | * the libunwind 0.99 code which are (amongst other contributors I may have |
7 | * forgotten): |
8 | * |
9 | * Copyright (C) 2002-2007 Hewlett-Packard Co |
10 | * Contributed by David Mosberger-Tang <davidm@hpl.hp.com> |
11 | * |
12 | * And the bugs have been added by: |
13 | * |
14 | * Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com> |
15 | * Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com> |
16 | * |
17 | */ |
18 | |
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 "debug.h" |
41 | #include "asm/bug.h" |
42 | #include "dso.h" |
43 | |
44 | extern int |
45 | UNW_OBJ(dwarf_search_unwind_table) (unw_addr_space_t as, |
46 | unw_word_t ip, |
47 | unw_dyn_info_t *di, |
48 | unw_proc_info_t *pi, |
49 | int need_unwind_info, void *arg); |
50 | |
51 | #define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table) |
52 | |
53 | extern int |
54 | UNW_OBJ(dwarf_find_debug_frame) (int found, unw_dyn_info_t *di_debug, |
55 | unw_word_t ip, |
56 | unw_word_t segbase, |
57 | const char *obj_name, unw_word_t start, |
58 | unw_word_t end); |
59 | |
60 | #define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame) |
61 | |
62 | #define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */ |
63 | #define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */ |
64 | |
65 | /* Pointer-encoding formats: */ |
66 | #define DW_EH_PE_omit 0xff |
67 | #define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */ |
68 | #define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */ |
69 | #define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */ |
70 | #define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */ |
71 | #define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */ |
72 | |
73 | /* Pointer-encoding application: */ |
74 | #define DW_EH_PE_absptr 0x00 /* absolute value */ |
75 | #define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */ |
76 | |
77 | /* |
78 | * The following are not documented by LSB v1.3, yet they are used by |
79 | * GCC, presumably they aren't documented by LSB since they aren't |
80 | * used on Linux: |
81 | */ |
82 | #define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */ |
83 | #define DW_EH_PE_aligned 0x50 /* aligned pointer */ |
84 | |
85 | /* Flags intentionally not handled, since they're not needed: |
86 | * #define DW_EH_PE_indirect 0x80 |
87 | * #define DW_EH_PE_uleb128 0x01 |
88 | * #define DW_EH_PE_udata2 0x02 |
89 | * #define DW_EH_PE_sleb128 0x09 |
90 | * #define DW_EH_PE_sdata2 0x0a |
91 | * #define DW_EH_PE_textrel 0x20 |
92 | * #define DW_EH_PE_datarel 0x30 |
93 | */ |
94 | |
95 | struct unwind_info { |
96 | struct perf_sample *sample; |
97 | struct machine *machine; |
98 | struct thread *thread; |
99 | bool best_effort; |
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 | |
112 | static 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 | |
172 | static int elf_section_address_and_offset(int fd, const char *name, u64 *address, u64 *offset) |
173 | { |
174 | Elf *elf; |
175 | GElf_Ehdr ehdr; |
176 | GElf_Shdr shdr; |
177 | int ret = -1; |
178 | |
179 | elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); |
180 | if (elf == NULL) |
181 | return -1; |
182 | |
183 | if (gelf_getehdr(elf, &ehdr) == NULL) |
184 | goto out_err; |
185 | |
186 | if (!elf_section_by_name(elf, &ehdr, &shdr, name, NULL)) |
187 | goto out_err; |
188 | |
189 | *address = shdr.sh_addr; |
190 | *offset = shdr.sh_offset; |
191 | ret = 0; |
192 | out_err: |
193 | elf_end(elf); |
194 | return ret; |
195 | } |
196 | |
197 | #ifndef NO_LIBUNWIND_DEBUG_FRAME |
198 | static u64 elf_section_offset(int fd, const char *name) |
199 | { |
200 | u64 address, offset = 0; |
201 | |
202 | if (elf_section_address_and_offset(fd, name, address: &address, offset: &offset)) |
203 | return 0; |
204 | |
205 | return offset; |
206 | } |
207 | #endif |
208 | |
209 | static u64 elf_base_address(int fd) |
210 | { |
211 | Elf *elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); |
212 | GElf_Phdr phdr; |
213 | u64 retval = 0; |
214 | size_t i, phdrnum = 0; |
215 | |
216 | if (elf == NULL) |
217 | return 0; |
218 | (void)elf_getphdrnum(elf, &phdrnum); |
219 | /* PT_LOAD segments are sorted by p_vaddr, so the first has the minimum p_vaddr. */ |
220 | for (i = 0; i < phdrnum; i++) { |
221 | if (gelf_getphdr(elf, i, &phdr) && phdr.p_type == PT_LOAD) { |
222 | retval = phdr.p_vaddr & -getpagesize(); |
223 | break; |
224 | } |
225 | } |
226 | |
227 | elf_end(elf); |
228 | return retval; |
229 | } |
230 | |
231 | #ifndef NO_LIBUNWIND_DEBUG_FRAME |
232 | static int elf_is_exec(int fd, const char *name) |
233 | { |
234 | Elf *elf; |
235 | GElf_Ehdr ehdr; |
236 | int retval = 0; |
237 | |
238 | elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL); |
239 | if (elf == NULL) |
240 | return 0; |
241 | if (gelf_getehdr(elf, &ehdr) == NULL) |
242 | goto out; |
243 | |
244 | retval = (ehdr.e_type == ET_EXEC); |
245 | |
246 | out: |
247 | elf_end(elf); |
248 | pr_debug("unwind: elf_is_exec(%s): %d\n" , name, retval); |
249 | return retval; |
250 | } |
251 | #endif |
252 | |
253 | struct table_entry { |
254 | u32 start_ip_offset; |
255 | u32 fde_offset; |
256 | }; |
257 | |
258 | struct eh_frame_hdr { |
259 | unsigned char version; |
260 | unsigned char eh_frame_ptr_enc; |
261 | unsigned char fde_count_enc; |
262 | unsigned char table_enc; |
263 | |
264 | /* |
265 | * The rest of the header is variable-length and consists of the |
266 | * following members: |
267 | * |
268 | * encoded_t eh_frame_ptr; |
269 | * encoded_t fde_count; |
270 | */ |
271 | |
272 | /* A single encoded pointer should not be more than 8 bytes. */ |
273 | u64 enc[2]; |
274 | |
275 | /* |
276 | * struct { |
277 | * encoded_t start_ip; |
278 | * encoded_t fde_addr; |
279 | * } binary_search_table[fde_count]; |
280 | */ |
281 | char data[]; |
282 | } __packed; |
283 | |
284 | static int unwind_spec_ehframe(struct dso *dso, struct machine *machine, |
285 | u64 offset, u64 *table_data_offset, u64 *fde_count) |
286 | { |
287 | struct eh_frame_hdr hdr; |
288 | u8 *enc = (u8 *) &hdr.enc; |
289 | u8 *end = (u8 *) &hdr.data; |
290 | ssize_t r; |
291 | |
292 | r = dso__data_read_offset(dso, machine, offset, |
293 | data: (u8 *) &hdr, size: sizeof(hdr)); |
294 | if (r != sizeof(hdr)) |
295 | return -EINVAL; |
296 | |
297 | /* We dont need eh_frame_ptr, just skip it. */ |
298 | dw_read_encoded_value(enc, end, hdr.eh_frame_ptr_enc); |
299 | |
300 | *fde_count = dw_read_encoded_value(enc, end, hdr.fde_count_enc); |
301 | *table_data_offset = enc - (u8 *) &hdr; |
302 | return 0; |
303 | } |
304 | |
305 | static int read_unwind_spec_eh_frame(struct dso *dso, struct unwind_info *ui, |
306 | u64 *table_data, u64 *segbase, |
307 | u64 *fde_count) |
308 | { |
309 | struct map_rb_node *map_node; |
310 | u64 base_addr = UINT64_MAX; |
311 | int ret, fd; |
312 | |
313 | if (dso->data.eh_frame_hdr_offset == 0) { |
314 | fd = dso__data_get_fd(dso, machine: ui->machine); |
315 | if (fd < 0) |
316 | return -EINVAL; |
317 | |
318 | /* Check the .eh_frame section for unwinding info */ |
319 | ret = elf_section_address_and_offset(fd, name: ".eh_frame_hdr" , |
320 | address: &dso->data.eh_frame_hdr_addr, |
321 | offset: &dso->data.eh_frame_hdr_offset); |
322 | dso->data.elf_base_addr = elf_base_address(fd); |
323 | dso__data_put_fd(dso); |
324 | if (ret || dso->data.eh_frame_hdr_offset == 0) |
325 | return -EINVAL; |
326 | } |
327 | |
328 | maps__for_each_entry(thread__maps(ui->thread), map_node) { |
329 | struct map *map = map_node->map; |
330 | u64 start = map__start(map); |
331 | |
332 | if (map__dso(map) == dso && start < base_addr) |
333 | base_addr = start; |
334 | } |
335 | base_addr -= dso->data.elf_base_addr; |
336 | /* Address of .eh_frame_hdr */ |
337 | *segbase = base_addr + dso->data.eh_frame_hdr_addr; |
338 | ret = unwind_spec_ehframe(dso, machine: ui->machine, offset: dso->data.eh_frame_hdr_offset, |
339 | table_data_offset: table_data, fde_count); |
340 | if (ret) |
341 | return ret; |
342 | /* binary_search_table offset plus .eh_frame_hdr address */ |
343 | *table_data += *segbase; |
344 | return 0; |
345 | } |
346 | |
347 | #ifndef NO_LIBUNWIND_DEBUG_FRAME |
348 | static int read_unwind_spec_debug_frame(struct dso *dso, |
349 | struct machine *machine, u64 *offset) |
350 | { |
351 | int fd; |
352 | u64 ofs = dso->data.debug_frame_offset; |
353 | |
354 | /* debug_frame can reside in: |
355 | * - dso |
356 | * - debug pointed by symsrc_filename |
357 | * - gnu_debuglink, which doesn't necessary |
358 | * has to be pointed by symsrc_filename |
359 | */ |
360 | if (ofs == 0) { |
361 | fd = dso__data_get_fd(dso, machine); |
362 | if (fd >= 0) { |
363 | ofs = elf_section_offset(fd, name: ".debug_frame" ); |
364 | dso__data_put_fd(dso); |
365 | } |
366 | |
367 | if (ofs <= 0) { |
368 | fd = open(dso->symsrc_filename, O_RDONLY); |
369 | if (fd >= 0) { |
370 | ofs = elf_section_offset(fd, name: ".debug_frame" ); |
371 | close(fd); |
372 | } |
373 | } |
374 | |
375 | if (ofs <= 0) { |
376 | char *debuglink = malloc(PATH_MAX); |
377 | int ret = 0; |
378 | |
379 | ret = dso__read_binary_type_filename( |
380 | dso, type: DSO_BINARY_TYPE__DEBUGLINK, |
381 | root_dir: machine->root_dir, filename: debuglink, PATH_MAX); |
382 | if (!ret) { |
383 | fd = open(debuglink, O_RDONLY); |
384 | if (fd >= 0) { |
385 | ofs = elf_section_offset(fd, |
386 | name: ".debug_frame" ); |
387 | close(fd); |
388 | } |
389 | } |
390 | if (ofs > 0) { |
391 | if (dso->symsrc_filename != NULL) { |
392 | pr_warning( |
393 | "%s: overwrite symsrc(%s,%s)\n" , |
394 | __func__, |
395 | dso->symsrc_filename, |
396 | debuglink); |
397 | zfree(&dso->symsrc_filename); |
398 | } |
399 | dso->symsrc_filename = debuglink; |
400 | } else { |
401 | free(debuglink); |
402 | } |
403 | } |
404 | |
405 | dso->data.debug_frame_offset = ofs; |
406 | } |
407 | |
408 | *offset = ofs; |
409 | if (*offset) |
410 | return 0; |
411 | |
412 | return -EINVAL; |
413 | } |
414 | #endif |
415 | |
416 | static struct map *find_map(unw_word_t ip, struct unwind_info *ui) |
417 | { |
418 | struct addr_location al; |
419 | struct map *ret; |
420 | |
421 | addr_location__init(al: &al); |
422 | thread__find_map(thread: ui->thread, PERF_RECORD_MISC_USER, addr: ip, al: &al); |
423 | ret = map__get(map: al.map); |
424 | addr_location__exit(al: &al); |
425 | return ret; |
426 | } |
427 | |
428 | static int |
429 | find_proc_info(unw_addr_space_t as, unw_word_t ip, unw_proc_info_t *pi, |
430 | int need_unwind_info, void *arg) |
431 | { |
432 | struct unwind_info *ui = arg; |
433 | struct map *map; |
434 | struct dso *dso; |
435 | unw_dyn_info_t di; |
436 | u64 table_data, segbase, fde_count; |
437 | int ret = -EINVAL; |
438 | |
439 | map = find_map(ip, ui); |
440 | if (!map) |
441 | return -EINVAL; |
442 | |
443 | dso = map__dso(map); |
444 | if (!dso) { |
445 | map__put(map); |
446 | return -EINVAL; |
447 | } |
448 | |
449 | pr_debug("unwind: find_proc_info dso %s\n" , dso->name); |
450 | |
451 | /* Check the .eh_frame section for unwinding info */ |
452 | if (!read_unwind_spec_eh_frame(dso, ui, table_data: &table_data, segbase: &segbase, fde_count: &fde_count)) { |
453 | memset(&di, 0, sizeof(di)); |
454 | di.format = UNW_INFO_FORMAT_REMOTE_TABLE; |
455 | di.start_ip = map__start(map); |
456 | di.end_ip = map__end(map); |
457 | di.u.rti.segbase = segbase; |
458 | di.u.rti.table_data = table_data; |
459 | di.u.rti.table_len = fde_count * sizeof(struct table_entry) |
460 | / sizeof(unw_word_t); |
461 | ret = dwarf_search_unwind_table(as, ip, &di, pi, |
462 | need_unwind_info, arg); |
463 | } |
464 | |
465 | #ifndef NO_LIBUNWIND_DEBUG_FRAME |
466 | /* Check the .debug_frame section for unwinding info */ |
467 | if (ret < 0 && |
468 | !read_unwind_spec_debug_frame(dso, machine: ui->machine, offset: &segbase)) { |
469 | int fd = dso__data_get_fd(dso, machine: ui->machine); |
470 | int is_exec = elf_is_exec(fd, name: dso->name); |
471 | u64 start = map__start(map); |
472 | unw_word_t base = is_exec ? 0 : start; |
473 | const char *symfile; |
474 | |
475 | if (fd >= 0) |
476 | dso__data_put_fd(dso); |
477 | |
478 | symfile = dso->symsrc_filename ?: dso->name; |
479 | |
480 | memset(&di, 0, sizeof(di)); |
481 | if (dwarf_find_debug_frame(0, &di, ip, base, symfile, start, map__end(map))) |
482 | ret = dwarf_search_unwind_table(as, ip, &di, pi, |
483 | need_unwind_info, arg); |
484 | } |
485 | #endif |
486 | map__put(map); |
487 | return ret; |
488 | } |
489 | |
490 | static int access_fpreg(unw_addr_space_t __maybe_unused as, |
491 | unw_regnum_t __maybe_unused num, |
492 | unw_fpreg_t __maybe_unused *val, |
493 | int __maybe_unused __write, |
494 | void __maybe_unused *arg) |
495 | { |
496 | pr_err("unwind: access_fpreg unsupported\n" ); |
497 | return -UNW_EINVAL; |
498 | } |
499 | |
500 | static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as, |
501 | unw_word_t __maybe_unused *dil_addr, |
502 | void __maybe_unused *arg) |
503 | { |
504 | return -UNW_ENOINFO; |
505 | } |
506 | |
507 | static int resume(unw_addr_space_t __maybe_unused as, |
508 | unw_cursor_t __maybe_unused *cu, |
509 | void __maybe_unused *arg) |
510 | { |
511 | pr_err("unwind: resume unsupported\n" ); |
512 | return -UNW_EINVAL; |
513 | } |
514 | |
515 | static int |
516 | get_proc_name(unw_addr_space_t __maybe_unused as, |
517 | unw_word_t __maybe_unused addr, |
518 | char __maybe_unused *bufp, size_t __maybe_unused buf_len, |
519 | unw_word_t __maybe_unused *offp, void __maybe_unused *arg) |
520 | { |
521 | pr_err("unwind: get_proc_name unsupported\n" ); |
522 | return -UNW_EINVAL; |
523 | } |
524 | |
525 | static int access_dso_mem(struct unwind_info *ui, unw_word_t addr, |
526 | unw_word_t *data) |
527 | { |
528 | struct map *map; |
529 | struct dso *dso; |
530 | ssize_t size; |
531 | |
532 | map = find_map(addr, ui); |
533 | if (!map) { |
534 | pr_debug("unwind: no map for %lx\n" , (unsigned long)addr); |
535 | return -1; |
536 | } |
537 | |
538 | dso = map__dso(map); |
539 | |
540 | if (!dso) { |
541 | map__put(map); |
542 | return -1; |
543 | } |
544 | |
545 | size = dso__data_read_addr(dso, map, machine: ui->machine, |
546 | addr: addr, data: (u8 *) data, size: sizeof(*data)); |
547 | map__put(map); |
548 | return !(size == sizeof(*data)); |
549 | } |
550 | |
551 | static int access_mem(unw_addr_space_t __maybe_unused as, |
552 | unw_word_t addr, unw_word_t *valp, |
553 | int __write, void *arg) |
554 | { |
555 | struct unwind_info *ui = arg; |
556 | const char *arch = perf_env__arch(env: ui->machine->env); |
557 | struct stack_dump *stack = &ui->sample->user_stack; |
558 | u64 start, end; |
559 | int offset; |
560 | int ret; |
561 | |
562 | /* Don't support write, probably not needed. */ |
563 | if (__write || !stack || !ui->sample->user_regs.regs) { |
564 | *valp = 0; |
565 | return 0; |
566 | } |
567 | |
568 | ret = perf_reg_value(regs: &start, idx: &ui->sample->user_regs, |
569 | perf_arch_reg_sp(arch)); |
570 | if (ret) |
571 | return ret; |
572 | |
573 | end = start + stack->size; |
574 | |
575 | /* Check overflow. */ |
576 | if (addr + sizeof(unw_word_t) < addr) |
577 | return -EINVAL; |
578 | |
579 | if (addr < start || addr + sizeof(unw_word_t) >= end) { |
580 | ret = access_dso_mem(ui, addr, valp); |
581 | if (ret) { |
582 | pr_debug("unwind: access_mem %p not inside range" |
583 | " 0x%" PRIx64 "-0x%" PRIx64 "\n" , |
584 | (void *) (uintptr_t) addr, start, end); |
585 | *valp = 0; |
586 | return ret; |
587 | } |
588 | return 0; |
589 | } |
590 | |
591 | offset = addr - start; |
592 | *valp = *(unw_word_t *)&stack->data[offset]; |
593 | pr_debug("unwind: access_mem addr %p val %lx, offset %d\n" , |
594 | (void *) (uintptr_t) addr, (unsigned long)*valp, offset); |
595 | return 0; |
596 | } |
597 | |
598 | static int access_reg(unw_addr_space_t __maybe_unused as, |
599 | unw_regnum_t regnum, unw_word_t *valp, |
600 | int __write, void *arg) |
601 | { |
602 | struct unwind_info *ui = arg; |
603 | int id, ret; |
604 | u64 val; |
605 | |
606 | /* Don't support write, I suspect we don't need it. */ |
607 | if (__write) { |
608 | pr_err("unwind: access_reg w %d\n" , regnum); |
609 | return 0; |
610 | } |
611 | |
612 | if (!ui->sample->user_regs.regs) { |
613 | *valp = 0; |
614 | return 0; |
615 | } |
616 | |
617 | id = LIBUNWIND__ARCH_REG_ID(regnum); |
618 | if (id < 0) |
619 | return -EINVAL; |
620 | |
621 | ret = perf_reg_value(regs: &val, idx: &ui->sample->user_regs, id); |
622 | if (ret) { |
623 | if (!ui->best_effort) |
624 | pr_err("unwind: can't read reg %d\n" , regnum); |
625 | return ret; |
626 | } |
627 | |
628 | *valp = (unw_word_t) val; |
629 | pr_debug("unwind: reg %d, val %lx\n" , regnum, (unsigned long)*valp); |
630 | return 0; |
631 | } |
632 | |
633 | static void put_unwind_info(unw_addr_space_t __maybe_unused as, |
634 | unw_proc_info_t *pi __maybe_unused, |
635 | void *arg __maybe_unused) |
636 | { |
637 | pr_debug("unwind: put_unwind_info called\n" ); |
638 | } |
639 | |
640 | static int entry(u64 ip, struct thread *thread, |
641 | unwind_entry_cb_t cb, void *arg) |
642 | { |
643 | struct unwind_entry e; |
644 | struct addr_location al; |
645 | int ret; |
646 | |
647 | addr_location__init(al: &al); |
648 | e.ms.sym = thread__find_symbol(thread, PERF_RECORD_MISC_USER, addr: ip, al: &al); |
649 | e.ip = ip; |
650 | e.ms.map = al.map; |
651 | e.ms.maps = al.maps; |
652 | |
653 | pr_debug("unwind: %s:ip = 0x%" PRIx64 " (0x%" PRIx64 ")\n" , |
654 | al.sym ? al.sym->name : "''" , |
655 | ip, |
656 | al.map ? map__map_ip(al.map, ip) : (u64) 0); |
657 | |
658 | ret = cb(&e, arg); |
659 | addr_location__exit(al: &al); |
660 | return ret; |
661 | } |
662 | |
663 | static void display_error(int err) |
664 | { |
665 | switch (err) { |
666 | case UNW_EINVAL: |
667 | pr_err("unwind: Only supports local.\n" ); |
668 | break; |
669 | case UNW_EUNSPEC: |
670 | pr_err("unwind: Unspecified error.\n" ); |
671 | break; |
672 | case UNW_EBADREG: |
673 | pr_err("unwind: Register unavailable.\n" ); |
674 | break; |
675 | default: |
676 | break; |
677 | } |
678 | } |
679 | |
680 | static unw_accessors_t accessors = { |
681 | .find_proc_info = find_proc_info, |
682 | .put_unwind_info = put_unwind_info, |
683 | .get_dyn_info_list_addr = get_dyn_info_list_addr, |
684 | .access_mem = access_mem, |
685 | .access_reg = access_reg, |
686 | .access_fpreg = access_fpreg, |
687 | .resume = resume, |
688 | .get_proc_name = get_proc_name, |
689 | }; |
690 | |
691 | static int _unwind__prepare_access(struct maps *maps) |
692 | { |
693 | void *addr_space = unw_create_addr_space(&accessors, 0); |
694 | |
695 | RC_CHK_ACCESS(maps)->addr_space = addr_space; |
696 | if (!addr_space) { |
697 | pr_err("unwind: Can't create unwind address space.\n" ); |
698 | return -ENOMEM; |
699 | } |
700 | |
701 | unw_set_caching_policy(addr_space, UNW_CACHE_GLOBAL); |
702 | return 0; |
703 | } |
704 | |
705 | static void _unwind__flush_access(struct maps *maps) |
706 | { |
707 | unw_flush_cache(maps__addr_space(maps), 0, 0); |
708 | } |
709 | |
710 | static void _unwind__finish_access(struct maps *maps) |
711 | { |
712 | unw_destroy_addr_space(maps__addr_space(maps)); |
713 | } |
714 | |
715 | static int get_entries(struct unwind_info *ui, unwind_entry_cb_t cb, |
716 | void *arg, int max_stack) |
717 | { |
718 | const char *arch = perf_env__arch(env: ui->machine->env); |
719 | u64 val; |
720 | unw_word_t ips[max_stack]; |
721 | unw_addr_space_t addr_space; |
722 | unw_cursor_t c; |
723 | int ret, i = 0; |
724 | |
725 | ret = perf_reg_value(regs: &val, idx: &ui->sample->user_regs, |
726 | perf_arch_reg_ip(arch)); |
727 | if (ret) |
728 | return ret; |
729 | |
730 | ips[i++] = (unw_word_t) val; |
731 | |
732 | /* |
733 | * If we need more than one entry, do the DWARF |
734 | * unwind itself. |
735 | */ |
736 | if (max_stack - 1 > 0) { |
737 | WARN_ONCE(!ui->thread, "WARNING: ui->thread is NULL" ); |
738 | addr_space = maps__addr_space(thread__maps(ui->thread)); |
739 | |
740 | if (addr_space == NULL) |
741 | return -1; |
742 | |
743 | ret = unw_init_remote(&c, addr_space, ui); |
744 | if (ret && !ui->best_effort) |
745 | display_error(err: ret); |
746 | |
747 | while (!ret && (unw_step(&c) > 0) && i < max_stack) { |
748 | unw_get_reg(&c, UNW_REG_IP, &ips[i]); |
749 | |
750 | /* |
751 | * Decrement the IP for any non-activation frames. |
752 | * this is required to properly find the srcline |
753 | * for caller frames. |
754 | * See also the documentation for dwfl_frame_pc(), |
755 | * which this code tries to replicate. |
756 | */ |
757 | if (unw_is_signal_frame(&c) <= 0) |
758 | --ips[i]; |
759 | |
760 | ++i; |
761 | } |
762 | |
763 | max_stack = i; |
764 | } |
765 | |
766 | /* |
767 | * Display what we got based on the order setup. |
768 | */ |
769 | for (i = 0; i < max_stack && !ret; i++) { |
770 | int j = i; |
771 | |
772 | if (callchain_param.order == ORDER_CALLER) |
773 | j = max_stack - i - 1; |
774 | ret = ips[j] ? entry(ips[j], ui->thread, cb, arg) : 0; |
775 | } |
776 | |
777 | return ret; |
778 | } |
779 | |
780 | static int _unwind__get_entries(unwind_entry_cb_t cb, void *arg, |
781 | struct thread *thread, |
782 | struct perf_sample *data, int max_stack, |
783 | bool best_effort) |
784 | { |
785 | struct unwind_info ui = { |
786 | .sample = data, |
787 | .thread = thread, |
788 | .machine = maps__machine(maps: thread__maps(thread)), |
789 | .best_effort = best_effort |
790 | }; |
791 | |
792 | if (!data->user_regs.regs) |
793 | return -EINVAL; |
794 | |
795 | if (max_stack <= 0) |
796 | return -EINVAL; |
797 | |
798 | return get_entries(ui: &ui, cb, arg, max_stack); |
799 | } |
800 | |
801 | static struct unwind_libunwind_ops |
802 | _unwind_libunwind_ops = { |
803 | .prepare_access = _unwind__prepare_access, |
804 | .flush_access = _unwind__flush_access, |
805 | .finish_access = _unwind__finish_access, |
806 | .get_entries = _unwind__get_entries, |
807 | }; |
808 | |
809 | #ifndef REMOTE_UNWIND_LIBUNWIND |
810 | struct unwind_libunwind_ops * |
811 | local_unwind_libunwind_ops = &_unwind_libunwind_ops; |
812 | #endif |
813 | |