1 /* Return backtrace of current program state.
2 Copyright (C) 1998-2015 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
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.
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.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If
17 not, see <http://www.gnu.org/licenses/>. */
23 #include <bits/libc-vdso.h>
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
29 +----------------+ +-----------------+
30 %r1 -> | %r1 last frame--------> | %r1 last frame--->... --> NULL
32 | cr save | | cr save |
34 | (unused) | | return address |
35 +----------------+ +-----------------+
40 long condition_register
;
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
];
52 /* We don't care about the rest, since the IP value is at 'uc' field. */
56 is_sigtramp_address (unsigned long nip
)
59 if (nip
== (unsigned long)__vdso_sigtramp_rt64
)
66 __backtrace (void **array
, int size
)
68 struct layout
*current
;
71 /* Force gcc to spill LR. */
72 asm volatile ("" : "=l"(current
));
74 /* Get the address on top-of-stack. */
75 asm volatile ("ld %0,0(1)" : "=r"(current
));
78 current
!= NULL
&& count
< size
;
79 current
= current
->next
, count
++)
81 array
[count
] = current
->return_address
;
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
))
87 struct signal_frame_64
*sigframe
= (struct signal_frame_64
*) current
;
88 array
[++count
] = (void*)sigframe
->uc
.uc_mcontext
.gp_regs
[PT_NIP
];
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
)
100 weak_alias (__backtrace
, backtrace
)
101 libc_hidden_def (__backtrace
)