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cfc91acd | 1 | /* Return backtrace of current program state. |
b168057a | 2 | Copyright (C) 1998-2015 Free Software Foundation, Inc. |
cfc91acd RM |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
6 | modify it under the terms of the GNU Library General Public License as | |
7 | published by the Free Software Foundation; either version 2 of the | |
8 | License, or (at your option) any later version. | |
9 | ||
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
13 | Library General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Library General Public | |
59ba27a6 PE |
16 | License along with the GNU C Library; see the file COPYING.LIB. If |
17 | not, see <http://www.gnu.org/licenses/>. */ | |
cfc91acd RM |
18 | |
19 | #include <execinfo.h> | |
20 | #include <stddef.h> | |
d400dcac AZ |
21 | #include <string.h> |
22 | #include <signal.h> | |
23 | #include <bits/libc-vdso.h> | |
cfc91acd RM |
24 | |
25 | /* This is the stack layout we see with every stack frame. | |
26 | Note that every routine is required by the ABI to lay out the stack | |
27 | like this. | |
28 | ||
29 | +----------------+ +-----------------+ | |
30 | %r1 -> | %r1 last frame--------> | %r1 last frame--->... --> NULL | |
31 | | | | | | |
32 | | cr save | | cr save | | |
33 | | | | | | |
34 | | (unused) | | return address | | |
35 | +----------------+ +-----------------+ | |
36 | */ | |
37 | struct layout | |
38 | { | |
70d9946a | 39 | struct layout *next; |
cfc91acd | 40 | long condition_register; |
70d9946a | 41 | void *return_address; |
cfc91acd RM |
42 | }; |
43 | ||
d400dcac AZ |
44 | /* Since the signal handler is just like any other function it needs to |
45 | save/restore its LR and it will save it into callers stack frame. | |
46 | Since a signal handler doesn't have a caller, the kernel creates a | |
47 | dummy frame to make it look like it has a caller. */ | |
48 | struct signal_frame_64 { | |
49 | #define SIGNAL_FRAMESIZE 128 | |
50 | char dummy[SIGNAL_FRAMESIZE]; | |
51 | struct ucontext uc; | |
52 | /* We don't care about the rest, since the IP value is at 'uc' field. */ | |
53 | }; | |
54 | ||
55 | static inline int | |
56 | is_sigtramp_address (unsigned long nip) | |
57 | { | |
58 | #ifdef SHARED | |
59 | if (nip == (unsigned long)__vdso_sigtramp_rt64) | |
60 | return 1; | |
61 | #endif | |
62 | return 0; | |
63 | } | |
64 | ||
cfc91acd RM |
65 | int |
66 | __backtrace (void **array, int size) | |
67 | { | |
68 | struct layout *current; | |
69 | int count; | |
70 | ||
71 | /* Force gcc to spill LR. */ | |
72 | asm volatile ("" : "=l"(current)); | |
73 | ||
74 | /* Get the address on top-of-stack. */ | |
75 | asm volatile ("ld %0,0(1)" : "=r"(current)); | |
cfc91acd RM |
76 | |
77 | for ( count = 0; | |
78 | current != NULL && count < size; | |
e782a927 | 79 | current = current->next, count++) |
d400dcac AZ |
80 | { |
81 | array[count] = current->return_address; | |
82 | ||
83 | /* Check if the symbol is the signal trampoline and get the interrupted | |
84 | * symbol address from the trampoline saved area. */ | |
85 | if (is_sigtramp_address ((unsigned long)current->return_address)) | |
86 | { | |
87 | struct signal_frame_64 *sigframe = (struct signal_frame_64*) current; | |
88 | array[++count] = (void*)sigframe->uc.uc_mcontext.gp_regs[PT_NIP]; | |
89 | } | |
90 | } | |
cfc91acd RM |
91 | |
92 | /* It's possible the second-last stack frame can't return | |
93 | (that is, it's __libc_start_main), in which case | |
94 | the CRT startup code will have set its LR to 'NULL'. */ | |
95 | if (count > 0 && array[count-1] == NULL) | |
96 | count--; | |
97 | ||
98 | return count; | |
99 | } | |
100 | weak_alias (__backtrace, backtrace) | |
0e66ade5 | 101 | libc_hidden_def (__backtrace) |