aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/powerpc/powerpc32/backtrace.c
blob: fc296bd5fbcf15932554cf373c96eabadabcc328 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
/* Return backtrace of current program state.
   Copyright (C) 1998-2015 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <execinfo.h>
#include <stddef.h>
#include <string.h>
#include <signal.h>
#include <bits/libc-vdso.h>

/* This is the stack layout we see with every stack frame.
   Note that every routine is required by the ABI to lay out the stack
   like this.

            +----------------+        +-----------------+
    %r1  -> | %r1 last frame--------> | %r1 last frame--->...  --> NULL
            |                |        |                 |
            | (unused)       |        | return address  |
            +----------------+        +-----------------+
*/
struct layout
{
  struct layout *next;
  void *return_address;
};

#define SIGNAL_FRAMESIZE 64

/* Since the signal handler is just like any other function it needs to
   save/restore its LR and it will save it into callers stack frame.
   Since a signal handler doesn't have a caller, the kernel creates a
   dummy frame to make it look like it has a caller.  */
struct signal_frame_32 {
  char               dummy[SIGNAL_FRAMESIZE];
  struct sigcontext  sctx;
  mcontext_t         mctx;
  /* We don't care about the rest, since IP value is at 'mctx' field.  */
};

static inline int
is_sigtramp_address (unsigned int nip)
{
#ifdef SHARED
  if (nip == (unsigned int)__vdso_sigtramp32)
    return 1;
#endif
  return 0;
}

struct rt_signal_frame_32 {
  char               dummy[SIGNAL_FRAMESIZE + 16];
  siginfo_t          info;
  struct ucontext    uc;
  /* We don't care about the rest, since IP value is at 'uc' field.  */
};

static inline int
is_sigtramp_address_rt (unsigned int nip)
{
#ifdef SHARED
  if (nip == (unsigned int)__vdso_sigtramp_rt32)
    return 1;
#endif
  return 0;
}

int
__backtrace (void **array, int size)
{
  struct layout *current;
  int count;

  /* Force gcc to spill LR.  */
  asm volatile ("" : "=l"(current));

  /* Get the address on top-of-stack.  */
  asm volatile ("lwz %0,0(1)" : "=r"(current));

  for (				count = 0;
       current != NULL && 	count < size;
       current = current->next, count++)
    {
      gregset_t *gregset = NULL;

      array[count] = current->return_address;

      /* Check if the symbol is the signal trampoline and get the interrupted
       * symbol address from the trampoline saved area.  */
      if (is_sigtramp_address ((unsigned int)current->return_address))
	{
	  struct signal_frame_32 *sigframe =
	    (struct signal_frame_32*) current;
          gregset = &sigframe->mctx.gregs;
        }
      else if (is_sigtramp_address_rt ((unsigned int)current->return_address))
	{
	  struct rt_signal_frame_32 *sigframe =
            (struct rt_signal_frame_32*) current;
          gregset = &sigframe->uc.uc_mcontext.uc_regs->gregs;
        }
      if (gregset)
	array[++count] = (void*)((*gregset)[PT_NIP]);
    }

  /* It's possible the second-last stack frame can't return
     (that is, it's __libc_start_main), in which case
     the CRT startup code will have set its LR to 'NULL'.  */
  if (count > 0 && array[count-1] == NULL)
    count--;

  return count;
}
weak_alias (__backtrace, backtrace)
libc_hidden_def (__backtrace)