1/* Copyright (C) 2005-2024 Free Software Foundation, Inc.
2
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 Lesser General Public License as
7 published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <stdio.h>
20#include <stdlib.h>
21#include <string.h>
22#include <sysdep.h>
23#include <signal.h>
24#include <execinfo.h>
25
26extern int
27_identify_sighandler (unsigned long fp, unsigned long pc,
28 unsigned long *pprev_fp, unsigned long *pprev_pc,
29 unsigned long *retaddr);
30
31static inline long
32get_frame_size (unsigned long instr)
33{
34 return abs (x: (short signed) (instr & 0xFFFF));
35}
36
37static unsigned long *
38find_frame_creation (unsigned long *pc)
39{
40 int i;
41
42 /* NOTE: Distance to search is arbitrary.
43 250 works well for most things,
44 750 picks up things like tcp_recvmsg,
45 1000 needed for fat_fill_super. */
46 for (i = 0; i < 1000; i++, pc--)
47 {
48 unsigned long instr;
49 unsigned long frame_size;
50
51 instr = *pc;
52
53 /* Is the instruction of the form
54 addik r1, r1, foo ? */
55 if ((instr & 0xFFFF0000) != 0x30210000)
56 continue;
57
58 frame_size = get_frame_size (instr);
59
60 if ((frame_size < 8) || (frame_size & 3))
61 return NULL;
62
63 return pc;
64 }
65 return NULL;
66}
67
68static int
69lookup_prev_stack_frame (unsigned long fp, unsigned long pc,
70 unsigned long *pprev_fp, unsigned long *pprev_pc,
71 unsigned long *retaddr)
72{
73 unsigned long *prologue = NULL;
74
75 int is_signalhandler = _identify_sighandler (fp, pc, pprev_fp,
76 pprev_pc, retaddr);
77
78 if (!is_signalhandler)
79 {
80 prologue = find_frame_creation (pc: (unsigned long *) pc);
81
82 if (prologue)
83 {
84 long frame_size = get_frame_size (instr: *prologue);
85 *pprev_fp = fp + frame_size;
86 if (*retaddr != 0)
87 *pprev_pc = *retaddr;
88 else
89 *pprev_pc = *(unsigned long *) fp;
90
91 *retaddr = 0;
92 if (!*pprev_pc || (*pprev_pc & 3))
93 prologue=0;
94 }
95 else
96 {
97 *pprev_pc = 0;
98 *pprev_fp = fp;
99 *retaddr = 0;
100 }
101 }
102 return (!*pprev_pc || (*pprev_pc & 3)) ? -1 : 0;
103}
104
105int
106__backtrace (void **array, int size)
107{
108 unsigned long pc, fp;
109 unsigned long ppc, pfp;
110 /* Return address(r15) is required in the signal handler case, since the
111 return address of the function which causes the signal may not be
112 recorded in the stack. */
113 unsigned long retaddr;
114
115 int count;
116 int rc = 0;
117
118 if (size <= 0)
119 return 0;
120
121 __asm__ __volatile__ ("mfs %0, rpc"
122 : "=r"(pc));
123
124 __asm__ __volatile__ ("add %0, r1, r0"
125 : "=r"(fp));
126
127 array[0] = (void *) pc;
128 retaddr = 0;
129 for (count = 1; count < size; count++)
130 {
131 rc = lookup_prev_stack_frame (fp, pc, pprev_fp: &pfp, pprev_pc: &ppc, retaddr: &retaddr);
132
133 fp = pfp;
134 pc = ppc;
135 array[count] = (void *) pc;
136 if (rc)
137 return count;
138 }
139 return count;
140}
141
142weak_alias (__backtrace, backtrace)
143libc_hidden_def (__backtrace)
144

source code of glibc/sysdeps/microblaze/backtrace.c