1 /* libunwind - a platform-independent unwind library
2 Copyright (C) 2003-2004 Hewlett-Packard Co
3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4
5 This file is part of libunwind.
6
7 Copyright (c) 2003 Hewlett-Packard Co.
8
9 Permission is hereby granted, free of charge, to any person obtaining
10 a copy of this software and associated documentation files (the
11 "Software"), to deal in the Software without restriction, including
12 without limitation the rights to use, copy, modify, merge, publish,
13 distribute, sublicense, and/or sell copies of the Software, and to
14 permit persons to whom the Software is furnished to do so, subject to
15 the following conditions:
16
17 The above copyright notice and this permission notice shall be
18 included in all copies or substantial portions of the Software.
19
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
24 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
25 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
26 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
27
28 #include "compiler.h"
29
30 #include <libunwind.h>
31 #include <stdio.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <unistd.h>
35
36 #include <sys/resource.h>
37 #include <sys/mman.h>
38 #include <sys/types.h>
39 #include <sys/wait.h>
40
41 #define panic(args...) \
42 { fprintf (stderr, args); exit (-1); }
43
44 void * stack_start;
45
46 #define PAGE_SIZE 4096
47
do_backtrace(void)48 void do_backtrace (void)
49 {
50 /*
51 We make the assumption that we are able to rewind far enough
52 (steps > 5) before touching the forbidden region in the stack,
53 at which point the unwinding should stop gracefully.
54 */
55 mprotect((void*)((uintptr_t)stack_start & ~(PAGE_SIZE - 1)),
56 PAGE_SIZE, PROT_NONE);
57
58 unw_cursor_t cursor;
59 unw_word_t ip, sp;
60 unw_context_t uc;
61 int ret;
62 int steps = 0;
63
64 unw_getcontext (&uc);
65 if (unw_init_local (&cursor, &uc) < 0)
66 panic ("unw_init_local failed!\n");
67
68 do
69 {
70 unw_get_reg (&cursor, UNW_REG_IP, &ip);
71 unw_get_reg (&cursor, UNW_REG_SP, &sp);
72
73 ret = unw_step (&cursor);
74 printf("ip=%lx, sp=%lx -> %d\n", (unsigned long)ip, (unsigned long)sp, ret);
75 if (ret < 0)
76 {
77 unw_get_reg (&cursor, UNW_REG_IP, &ip);
78 }
79 steps ++;
80 }
81 while (ret > 0);
82
83 if (steps < 5)
84 {
85 printf("not enough steps: %d, need 5\n", steps);
86 exit(-1);
87 }
88 printf("success, steps: %d\n", steps);
89
90 mprotect((void*)((uintptr_t)stack_start & ~(PAGE_SIZE - 1)),
91 PAGE_SIZE, PROT_READ|PROT_WRITE);
92 }
93
consume_and_run(int depth)94 void NOINLINE consume_and_run (int depth)
95 {
96 unw_cursor_t cursor;
97 unw_context_t uc;
98 char string[1024];
99
100 sprintf (string, "hello %p %p\n", &cursor, &uc);
101 if (depth == 0) {
102 do_backtrace();
103 } else {
104 consume_and_run(depth - 1);
105 }
106 }
107
108 int
main(int argc,char ** argv UNUSED)109 main (int argc, char **argv UNUSED)
110 {
111 int start;
112 unw_context_t uc;
113 unw_cursor_t cursor;
114
115 stack_start = &start;
116
117 /*
118 We need to make the frame at least the size protected by
119 the mprotect call so we are not forbidding access to
120 unrelated regions.
121 */
122 char string[PAGE_SIZE];
123 sprintf (string, "hello\n");
124
125 // Initialize pipe mem validate check, opens file descriptors
126 unw_getcontext(&uc);
127 if (unw_init_local (&cursor, &uc) < 0)
128 panic ("unw_init_local failed!\n");
129
130 int i;
131 for (i = 3; i < 10; i++)
132 {
133
134 pid_t childpid = fork();
135 if (!childpid)
136 {
137 /* Close fds and make sure we still work */
138 close(i);
139 }
140
141 int status;
142 if (childpid)
143 {
144 wait(&status);
145 if (WIFEXITED(status))
146 return WEXITSTATUS(status);
147 else
148 return -1;
149 }
150 else
151 {
152 consume_and_run (10);
153
154 return 0;
155 }
156 }
157
158 return 0;
159 }
160