summaryrefslogtreecommitdiff
path: root/xserver/os/backtrace.c
blob: f3255c738f04b62036679439d74019f13077205b (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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
/*
 * Copyright 2008 Red Hat, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include "os.h"
#include "misc.h"

#ifdef HAVE_BACKTRACE
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <dlfcn.h>
#include <execinfo.h>

void xorg_backtrace(void)
{
    void *array[64];
    const char *mod;
    int size, i;
    Dl_info info;
    ErrorF("\nBacktrace:\n");
    size = backtrace(array, 64);
    for (i = 0; i < size; i++) {
	int rc = dladdr(array[i], &info);
	if (rc == 0) {
	    ErrorF("%d: ?? [%p]\n", i, array[i]);
	    continue;
	}
	mod = (info.dli_fname && *info.dli_fname) ? info.dli_fname : "(vdso)";
	if (info.dli_saddr)
	    ErrorF("%d: %s (%s+0x%lx) [%p]\n", i, mod,
		   info.dli_sname, (long unsigned int)((char *) array[i] - (char *) info.dli_saddr), array[i]);
	else
	    ErrorF("%d: %s (%p+0x%lx) [%p]\n", i, mod,
		   info.dli_fbase, (long unsigned int)((char *) array[i] - (char *) info.dli_fbase), array[i]);
    }
}

#else /* not glibc or glibc < 2.1 */

# if defined(sun) && defined(__SVR4)
#  define HAVE_PSTACK
# endif

# if defined(HAVE_WALKCONTEXT) /* Solaris 9 & later */

# include <ucontext.h>
# include <signal.h>
# include <dlfcn.h>
# include <sys/elf.h>

#ifdef _LP64
# define ElfSym Elf64_Sym
#else
# define ElfSym Elf32_Sym
#endif

/* Called for each frame on the stack to print it's contents */
static int xorg_backtrace_frame(uintptr_t pc, int signo, void *arg)
{
    Dl_info dlinfo;
    ElfSym *dlsym;
    char header[32];
    int depth = *((int *) arg);

    if (signo) {
	char signame[SIG2STR_MAX];

	if (sig2str(signo, signame) != 0) {
	    strcpy(signame, "unknown");
	}

	ErrorF("** Signal %d (%s)\n", signo, signame);
    }

    snprintf(header, sizeof(header), "%d: 0x%lx", depth, pc);
    *((int *) arg) = depth + 1;

    /* Ask system dynamic loader for info on the address */
    if (dladdr1((void *) pc, &dlinfo, (void **) &dlsym, RTLD_DL_SYMENT)) {
	unsigned long offset = pc - (uintptr_t) dlinfo.dli_saddr;
	const char *symname;
	
	if (offset < dlsym->st_size) { /* inside a function */
	    symname = dlinfo.dli_sname;
	} else { /* found which file it was in, but not which function */
	    symname = "<section start>";
	    offset = pc - (uintptr_t)dlinfo.dli_fbase;
	}
	ErrorF("%s: %s:%s+0x%lx\n", header, dlinfo.dli_fname,
	       symname, offset);

    } else {
	/* Couldn't find symbol info from system dynamic loader, should
	 * probably poke elfloader here, but haven't written that code yet,
	 * so we just print the pc.
	 */
	ErrorF("%s\n", header);
    }

    return 0;
}
# endif /* HAVE_WALKCONTEXT */

# ifdef HAVE_PSTACK
static int xorg_backtrace_pstack(void) {
    pid_t kidpid;
    int pipefd[2];

    if (pipe(pipefd) != 0) {
	return -1;
    }

    kidpid = fork1();

    if (kidpid == -1) {
	/* ERROR */
	return -1;
    } else if (kidpid == 0) {
	/* CHILD */
	char parent[16];
	
	seteuid(0);
	close(STDIN_FILENO);
	close(STDOUT_FILENO);
	dup2(pipefd[1],STDOUT_FILENO);
	closefrom(STDERR_FILENO);

	snprintf(parent, sizeof(parent), "%d", getppid());
	execle("/usr/bin/pstack", "pstack", parent, NULL);
	exit(1);
    } else {
	/* PARENT */
	char btline[256];
	int kidstat;
	int bytesread;
	int done = 0;
	
	close(pipefd[1]);

	while (!done) {
	    bytesread = read(pipefd[0], btline, sizeof(btline) - 1);

	    if (bytesread > 0) {
		btline[bytesread] = 0;
		ErrorF("%s", btline);
	    }
	    else if ((bytesread < 0) ||
		     ((errno != EINTR) && (errno != EAGAIN)))
		done = 1;
	}
	close(pipefd[0]);
	waitpid(kidpid, &kidstat, 0);
	if (kidstat != 0)
	    return -1;
    }
    return 0;
}
# endif /* HAVE_PSTACK */


# if defined(HAVE_PSTACK) || defined(HAVE_WALKCONTEXT)

void xorg_backtrace(void) {

    ErrorF("\nBacktrace:\n");

#  ifdef HAVE_PSTACK
/* First try fork/exec of pstack - otherwise fall back to walkcontext
   pstack is preferred since it can print names of non-exported functions */

    if (xorg_backtrace_pstack() < 0)
#  endif	
    {
#  ifdef HAVE_WALKCONTEXT
	ucontext_t u;
	int depth = 1;
	
	if (getcontext(&u) == 0)
	    walkcontext(&u, xorg_backtrace_frame, &depth);
	else
#  endif
	    Error("Failed to get backtrace info");
    }
    ErrorF("\n");	
}

# else

/* Default fallback if we can't find any way to get a backtrace */
void xorg_backtrace(void) { return; }

# endif
#endif