2 * Post mortem Dwarf CFI based unwinding on top of regs and stack dumps.
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
8 * Copyright (C) 2002-2007 Hewlett-Packard Co
9 * Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
11 * And the bugs have been added by:
13 * Copyright (C) 2010, Frederic Weisbecker <fweisbec@gmail.com>
14 * Copyright (C) 2012, Jiri Olsa <jolsa@redhat.com>
24 #include <linux/list.h>
25 #include <libunwind.h>
26 #include <libunwind-ptrace.h>
29 #include "perf_regs.h"
36 UNW_OBJ(dwarf_search_unwind_table
) (unw_addr_space_t as
,
40 int need_unwind_info
, void *arg
);
42 #define dwarf_search_unwind_table UNW_OBJ(dwarf_search_unwind_table)
45 UNW_OBJ(dwarf_find_debug_frame
) (int found
, unw_dyn_info_t
*di_debug
,
48 const char *obj_name
, unw_word_t start
,
51 #define dwarf_find_debug_frame UNW_OBJ(dwarf_find_debug_frame)
53 #define DW_EH_PE_FORMAT_MASK 0x0f /* format of the encoded value */
54 #define DW_EH_PE_APPL_MASK 0x70 /* how the value is to be applied */
56 /* Pointer-encoding formats: */
57 #define DW_EH_PE_omit 0xff
58 #define DW_EH_PE_ptr 0x00 /* pointer-sized unsigned value */
59 #define DW_EH_PE_udata4 0x03 /* unsigned 32-bit value */
60 #define DW_EH_PE_udata8 0x04 /* unsigned 64-bit value */
61 #define DW_EH_PE_sdata4 0x0b /* signed 32-bit value */
62 #define DW_EH_PE_sdata8 0x0c /* signed 64-bit value */
64 /* Pointer-encoding application: */
65 #define DW_EH_PE_absptr 0x00 /* absolute value */
66 #define DW_EH_PE_pcrel 0x10 /* rel. to addr. of encoded value */
69 * The following are not documented by LSB v1.3, yet they are used by
70 * GCC, presumably they aren't documented by LSB since they aren't
73 #define DW_EH_PE_funcrel 0x40 /* start-of-procedure-relative */
74 #define DW_EH_PE_aligned 0x50 /* aligned pointer */
76 /* Flags intentionaly not handled, since they're not needed:
77 * #define DW_EH_PE_indirect 0x80
78 * #define DW_EH_PE_uleb128 0x01
79 * #define DW_EH_PE_udata2 0x02
80 * #define DW_EH_PE_sleb128 0x09
81 * #define DW_EH_PE_sdata2 0x0a
82 * #define DW_EH_PE_textrel 0x20
83 * #define DW_EH_PE_datarel 0x30
87 struct perf_sample
*sample
;
88 struct machine
*machine
;
89 struct thread
*thread
;
92 #define dw_read(ptr, type, end) ({ \
93 type *__p = (type *) ptr; \
95 if ((__p + 1) > (type *) end) \
98 ptr = (typeof(ptr)) __p; \
102 static int __dw_read_encoded_value(u8
**p
, u8
*end
, u64
*val
,
113 *val
= dw_read(cur
, unsigned long, end
);
119 switch (encoding
& DW_EH_PE_APPL_MASK
) {
120 case DW_EH_PE_absptr
:
123 *val
= (unsigned long) cur
;
129 if ((encoding
& 0x07) == 0x00)
130 encoding
|= DW_EH_PE_udata4
;
132 switch (encoding
& DW_EH_PE_FORMAT_MASK
) {
133 case DW_EH_PE_sdata4
:
134 *val
+= dw_read(cur
, s32
, end
);
136 case DW_EH_PE_udata4
:
137 *val
+= dw_read(cur
, u32
, end
);
139 case DW_EH_PE_sdata8
:
140 *val
+= dw_read(cur
, s64
, end
);
142 case DW_EH_PE_udata8
:
143 *val
+= dw_read(cur
, u64
, end
);
154 #define dw_read_encoded_value(ptr, end, enc) ({ \
156 if (__dw_read_encoded_value(&ptr, end, &__v, enc)) { \
162 static u64
elf_section_offset(int fd
, const char *name
)
169 elf
= elf_begin(fd
, PERF_ELF_C_READ_MMAP
, NULL
);
174 if (gelf_getehdr(elf
, &ehdr
) == NULL
)
177 if (!elf_section_by_name(elf
, &ehdr
, &shdr
, name
, NULL
))
180 offset
= shdr
.sh_offset
;
192 struct eh_frame_hdr
{
193 unsigned char version
;
194 unsigned char eh_frame_ptr_enc
;
195 unsigned char fde_count_enc
;
196 unsigned char table_enc
;
199 * The rest of the header is variable-length and consists of the
202 * encoded_t eh_frame_ptr;
203 * encoded_t fde_count;
206 /* A single encoded pointer should not be more than 8 bytes. */
211 * encoded_t start_ip;
212 * encoded_t fde_addr;
213 * } binary_search_table[fde_count];
218 static int unwind_spec_ehframe(struct dso
*dso
, struct machine
*machine
,
219 u64 offset
, u64
*table_data
, u64
*segbase
,
222 struct eh_frame_hdr hdr
;
223 u8
*enc
= (u8
*) &hdr
.enc
;
224 u8
*end
= (u8
*) &hdr
.data
;
227 r
= dso__data_read_offset(dso
, machine
, offset
,
228 (u8
*) &hdr
, sizeof(hdr
));
229 if (r
!= sizeof(hdr
))
232 /* We dont need eh_frame_ptr, just skip it. */
233 dw_read_encoded_value(enc
, end
, hdr
.eh_frame_ptr_enc
);
235 *fde_count
= dw_read_encoded_value(enc
, end
, hdr
.fde_count_enc
);
237 *table_data
= (enc
- (u8
*) &hdr
) + offset
;
241 static int read_unwind_spec_eh_frame(struct dso
*dso
, struct machine
*machine
,
242 u64
*table_data
, u64
*segbase
,
245 int ret
= -EINVAL
, fd
;
248 fd
= dso__data_fd(dso
, machine
);
252 /* Check the .eh_frame section for unwinding info */
253 offset
= elf_section_offset(fd
, ".eh_frame_hdr");
256 ret
= unwind_spec_ehframe(dso
, machine
, offset
,
263 #ifndef NO_LIBUNWIND_DEBUG_FRAME
264 static int read_unwind_spec_debug_frame(struct dso
*dso
,
265 struct machine
*machine
, u64
*offset
)
267 int fd
= dso__data_fd(dso
, machine
);
272 /* Check the .debug_frame section for unwinding info */
273 *offset
= elf_section_offset(fd
, ".debug_frame");
282 static struct map
*find_map(unw_word_t ip
, struct unwind_info
*ui
)
284 struct addr_location al
;
286 thread__find_addr_map(ui
->thread
, ui
->machine
, PERF_RECORD_MISC_USER
,
287 MAP__FUNCTION
, ip
, &al
);
292 find_proc_info(unw_addr_space_t as
, unw_word_t ip
, unw_proc_info_t
*pi
,
293 int need_unwind_info
, void *arg
)
295 struct unwind_info
*ui
= arg
;
298 u64 table_data
, segbase
, fde_count
;
300 map
= find_map(ip
, ui
);
301 if (!map
|| !map
->dso
)
304 pr_debug("unwind: find_proc_info dso %s\n", map
->dso
->name
);
306 /* Check the .eh_frame section for unwinding info */
307 if (!read_unwind_spec_eh_frame(map
->dso
, ui
->machine
,
308 &table_data
, &segbase
, &fde_count
)) {
309 memset(&di
, 0, sizeof(di
));
310 di
.format
= UNW_INFO_FORMAT_REMOTE_TABLE
;
311 di
.start_ip
= map
->start
;
312 di
.end_ip
= map
->end
;
313 di
.u
.rti
.segbase
= map
->start
+ segbase
;
314 di
.u
.rti
.table_data
= map
->start
+ table_data
;
315 di
.u
.rti
.table_len
= fde_count
* sizeof(struct table_entry
)
316 / sizeof(unw_word_t
);
317 return dwarf_search_unwind_table(as
, ip
, &di
, pi
,
318 need_unwind_info
, arg
);
321 #ifndef NO_LIBUNWIND_DEBUG_FRAME
322 /* Check the .debug_frame section for unwinding info */
323 if (!read_unwind_spec_debug_frame(map
->dso
, ui
->machine
, &segbase
)) {
324 memset(&di
, 0, sizeof(di
));
325 if (dwarf_find_debug_frame(0, &di
, ip
, 0, map
->dso
->name
,
326 map
->start
, map
->end
))
327 return dwarf_search_unwind_table(as
, ip
, &di
, pi
,
328 need_unwind_info
, arg
);
335 static int access_fpreg(unw_addr_space_t __maybe_unused as
,
336 unw_regnum_t __maybe_unused num
,
337 unw_fpreg_t __maybe_unused
*val
,
338 int __maybe_unused __write
,
339 void __maybe_unused
*arg
)
341 pr_err("unwind: access_fpreg unsupported\n");
345 static int get_dyn_info_list_addr(unw_addr_space_t __maybe_unused as
,
346 unw_word_t __maybe_unused
*dil_addr
,
347 void __maybe_unused
*arg
)
352 static int resume(unw_addr_space_t __maybe_unused as
,
353 unw_cursor_t __maybe_unused
*cu
,
354 void __maybe_unused
*arg
)
356 pr_err("unwind: resume unsupported\n");
361 get_proc_name(unw_addr_space_t __maybe_unused as
,
362 unw_word_t __maybe_unused addr
,
363 char __maybe_unused
*bufp
, size_t __maybe_unused buf_len
,
364 unw_word_t __maybe_unused
*offp
, void __maybe_unused
*arg
)
366 pr_err("unwind: get_proc_name unsupported\n");
370 static int access_dso_mem(struct unwind_info
*ui
, unw_word_t addr
,
373 struct addr_location al
;
376 thread__find_addr_map(ui
->thread
, ui
->machine
, PERF_RECORD_MISC_USER
,
377 MAP__FUNCTION
, addr
, &al
);
379 pr_debug("unwind: no map for %lx\n", (unsigned long)addr
);
386 size
= dso__data_read_addr(al
.map
->dso
, al
.map
, ui
->machine
,
387 addr
, (u8
*) data
, sizeof(*data
));
389 return !(size
== sizeof(*data
));
392 static int access_mem(unw_addr_space_t __maybe_unused as
,
393 unw_word_t addr
, unw_word_t
*valp
,
394 int __write
, void *arg
)
396 struct unwind_info
*ui
= arg
;
397 struct stack_dump
*stack
= &ui
->sample
->user_stack
;
402 /* Don't support write, probably not needed. */
403 if (__write
|| !stack
|| !ui
->sample
->user_regs
.regs
) {
408 ret
= perf_reg_value(&start
, &ui
->sample
->user_regs
, PERF_REG_SP
);
412 end
= start
+ stack
->size
;
414 /* Check overflow. */
415 if (addr
+ sizeof(unw_word_t
) < addr
)
418 if (addr
< start
|| addr
+ sizeof(unw_word_t
) >= end
) {
419 ret
= access_dso_mem(ui
, addr
, valp
);
421 pr_debug("unwind: access_mem %p not inside range"
422 " 0x%" PRIx64
"-0x%" PRIx64
"\n",
423 (void *) addr
, start
, end
);
430 offset
= addr
- start
;
431 *valp
= *(unw_word_t
*)&stack
->data
[offset
];
432 pr_debug("unwind: access_mem addr %p val %lx, offset %d\n",
433 (void *) addr
, (unsigned long)*valp
, offset
);
437 static int access_reg(unw_addr_space_t __maybe_unused as
,
438 unw_regnum_t regnum
, unw_word_t
*valp
,
439 int __write
, void *arg
)
441 struct unwind_info
*ui
= arg
;
445 /* Don't support write, I suspect we don't need it. */
447 pr_err("unwind: access_reg w %d\n", regnum
);
451 if (!ui
->sample
->user_regs
.regs
) {
456 id
= libunwind__arch_reg_id(regnum
);
460 ret
= perf_reg_value(&val
, &ui
->sample
->user_regs
, id
);
462 pr_err("unwind: can't read reg %d\n", regnum
);
466 *valp
= (unw_word_t
) val
;
467 pr_debug("unwind: reg %d, val %lx\n", regnum
, (unsigned long)*valp
);
471 static void put_unwind_info(unw_addr_space_t __maybe_unused as
,
472 unw_proc_info_t
*pi __maybe_unused
,
473 void *arg __maybe_unused
)
475 pr_debug("unwind: put_unwind_info called\n");
478 static int entry(u64 ip
, struct thread
*thread
, struct machine
*machine
,
479 unwind_entry_cb_t cb
, void *arg
)
481 struct unwind_entry e
;
482 struct addr_location al
;
484 thread__find_addr_location(thread
, machine
,
485 PERF_RECORD_MISC_USER
,
486 MAP__FUNCTION
, ip
, &al
);
492 pr_debug("unwind: %s:ip = 0x%" PRIx64
" (0x%" PRIx64
")\n",
493 al
.sym
? al
.sym
->name
: "''",
495 al
.map
? al
.map
->map_ip(al
.map
, ip
) : (u64
) 0);
500 static void display_error(int err
)
504 pr_err("unwind: Only supports local.\n");
507 pr_err("unwind: Unspecified error.\n");
510 pr_err("unwind: Register unavailable.\n");
517 static unw_accessors_t accessors
= {
518 .find_proc_info
= find_proc_info
,
519 .put_unwind_info
= put_unwind_info
,
520 .get_dyn_info_list_addr
= get_dyn_info_list_addr
,
521 .access_mem
= access_mem
,
522 .access_reg
= access_reg
,
523 .access_fpreg
= access_fpreg
,
525 .get_proc_name
= get_proc_name
,
528 static int get_entries(struct unwind_info
*ui
, unwind_entry_cb_t cb
,
529 void *arg
, int max_stack
)
531 unw_addr_space_t addr_space
;
535 addr_space
= unw_create_addr_space(&accessors
, 0);
537 pr_err("unwind: Can't create unwind address space.\n");
541 ret
= unw_init_remote(&c
, addr_space
, ui
);
545 while (!ret
&& (unw_step(&c
) > 0) && max_stack
--) {
548 unw_get_reg(&c
, UNW_REG_IP
, &ip
);
549 ret
= ip
? entry(ip
, ui
->thread
, ui
->machine
, cb
, arg
) : 0;
552 unw_destroy_addr_space(addr_space
);
556 int unwind__get_entries(unwind_entry_cb_t cb
, void *arg
,
557 struct machine
*machine
, struct thread
*thread
,
558 struct perf_sample
*data
, int max_stack
)
561 struct unwind_info ui
= {
568 if (!data
->user_regs
.regs
)
571 ret
= perf_reg_value(&ip
, &data
->user_regs
, PERF_REG_IP
);
575 ret
= entry(ip
, thread
, machine
, cb
, arg
);
579 return --max_stack
> 0 ? get_entries(&ui
, cb
, arg
, max_stack
) : 0;