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1 /* Return backtrace of current program state.
2 Copyright (C) 1998-2020 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 <https://www.gnu.org/licenses/>. */
25 #include <libc-vdso.h>
27 /* This is the stack layout we see with every stack frame.
28 Note that every routine is required by the ABI to lay out the stack
31 +----------------+ +-----------------+
32 %r1 -> | %r1 last frame--------> | %r1 last frame--->... --> NULL
34 | cr save | | cr save |
36 | (unused) | | return address |
37 +----------------+ +-----------------+
42 long int condition_register
;
46 /* Since the signal handler is just like any other function it needs to
47 save/restore its LR and it will save it into callers stack frame.
48 Since a signal handler doesn't have a caller, the kernel creates a
49 dummy frame to make it look like it has a caller. */
50 struct signal_frame_64
{
51 #define SIGNAL_FRAMESIZE 128
52 char dummy
[SIGNAL_FRAMESIZE
];
54 /* We don't care about the rest, since the IP value is at 'uc' field. */
58 is_sigtramp_address (void *nip
)
60 #ifdef HAVE_SIGTRAMP_RT64
61 if (nip
== GLRO (dl_vdso_sigtramp_rt64
))
68 __backtrace (void **array
, int size
)
70 struct layout
*current
;
73 /* Force gcc to spill LR. */
74 asm volatile ("" : "=l"(current
));
76 /* Get the address on top-of-stack. */
77 asm volatile ("ld %0,0(1)" : "=r"(current
));
80 current
!= NULL
&& count
< size
;
81 current
= current
->next
, count
++)
83 array
[count
] = current
->return_address
;
85 /* Check if the symbol is the signal trampoline and get the interrupted
86 * symbol address from the trampoline saved area. */
87 if (is_sigtramp_address (current
->return_address
))
89 struct signal_frame_64
*sigframe
= (struct signal_frame_64
*) current
;
90 array
[++count
] = (void*) sigframe
->uc
.uc_mcontext
.gp_regs
[PT_NIP
];
91 current
= (void*) sigframe
->uc
.uc_mcontext
.gp_regs
[PT_R1
];
95 /* It's possible the second-last stack frame can't return
96 (that is, it's __libc_start_main), in which case
97 the CRT startup code will have set its LR to 'NULL'. */
98 if (count
> 0 && array
[count
-1] == NULL
)
103 weak_alias (__backtrace
, backtrace
)
104 libc_hidden_def (__backtrace
)
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