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
|
//===-- sanitizer_unwind_linux_libcdep.cpp --------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains the unwind.h-based (aka "slow") stack unwinding routines
// available to the tools on Linux, Android, NetBSD, FreeBSD, and Solaris.
//===----------------------------------------------------------------------===//
#include "sanitizer_platform.h"
#if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
SANITIZER_SOLARIS
#include "sanitizer_common.h"
#include "sanitizer_stacktrace.h"
#if SANITIZER_ANDROID
#include <dlfcn.h> // for dlopen()
#endif
#if SANITIZER_FREEBSD
#define _GNU_SOURCE // to declare _Unwind_Backtrace() from <unwind.h>
#endif
#include <unwind.h>
namespace __sanitizer {
namespace {
//---------------------------- UnwindSlow --------------------------------------
typedef struct {
uptr absolute_pc;
uptr stack_top;
uptr stack_size;
} backtrace_frame_t;
extern "C" {
typedef void *(*acquire_my_map_info_list_func)();
typedef void (*release_my_map_info_list_func)(void *map);
typedef sptr (*unwind_backtrace_signal_arch_func)(
void *siginfo, void *sigcontext, void *map_info_list,
backtrace_frame_t *backtrace, uptr ignore_depth, uptr max_depth);
acquire_my_map_info_list_func acquire_my_map_info_list;
release_my_map_info_list_func release_my_map_info_list;
unwind_backtrace_signal_arch_func unwind_backtrace_signal_arch;
} // extern "C"
#if defined(__arm__) && !SANITIZER_NETBSD
// NetBSD uses dwarf EH
#define UNWIND_STOP _URC_END_OF_STACK
#define UNWIND_CONTINUE _URC_NO_REASON
#else
#define UNWIND_STOP _URC_NORMAL_STOP
#define UNWIND_CONTINUE _URC_NO_REASON
#endif
uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
#if defined(__arm__) && !SANITIZER_APPLE
uptr val;
_Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
15 /* r15 = PC */, _UVRSD_UINT32, &val);
CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
// Clear the Thumb bit.
return val & ~(uptr)1;
#else
return (uptr)_Unwind_GetIP(ctx);
#endif
}
struct UnwindTraceArg {
BufferedStackTrace *stack;
u32 max_depth;
};
_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
UnwindTraceArg *arg = (UnwindTraceArg*)param;
CHECK_LT(arg->stack->size, arg->max_depth);
uptr pc = Unwind_GetIP(ctx);
const uptr kPageSize = GetPageSizeCached();
// Let's assume that any pointer in the 0th page (i.e. <0x1000 on i386 and
// x86_64) is invalid and stop unwinding here. If we're adding support for
// a platform where this isn't true, we need to reconsider this check.
if (pc < kPageSize) return UNWIND_STOP;
arg->stack->trace_buffer[arg->stack->size++] = pc;
if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
return UNWIND_CONTINUE;
}
} // namespace
#if SANITIZER_ANDROID
void SanitizerInitializeUnwinder() {
if (AndroidGetApiLevel() >= ANDROID_LOLLIPOP_MR1) return;
// Pre-lollipop Android can not unwind through signal handler frames with
// libgcc unwinder, but it has a libcorkscrew.so library with the necessary
// workarounds.
void *p = dlopen("libcorkscrew.so", RTLD_LAZY);
if (!p) {
VReport(1,
"Failed to open libcorkscrew.so. You may see broken stack traces "
"in SEGV reports.");
return;
}
acquire_my_map_info_list =
(acquire_my_map_info_list_func)(uptr)dlsym(p, "acquire_my_map_info_list");
release_my_map_info_list =
(release_my_map_info_list_func)(uptr)dlsym(p, "release_my_map_info_list");
unwind_backtrace_signal_arch = (unwind_backtrace_signal_arch_func)(uptr)dlsym(
p, "unwind_backtrace_signal_arch");
if (!acquire_my_map_info_list || !release_my_map_info_list ||
!unwind_backtrace_signal_arch) {
VReport(1,
"Failed to find one of the required symbols in libcorkscrew.so. "
"You may see broken stack traces in SEGV reports.");
acquire_my_map_info_list = 0;
unwind_backtrace_signal_arch = 0;
release_my_map_info_list = 0;
}
}
#endif
void BufferedStackTrace::UnwindSlow(uptr pc, u32 max_depth) {
CHECK_GE(max_depth, 2);
size = 0;
UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
_Unwind_Backtrace(Unwind_Trace, &arg);
// We need to pop a few frames so that pc is on top.
uptr to_pop = LocatePcInTrace(pc);
// trace_buffer[0] belongs to the current function so we always pop it,
// unless there is only 1 frame in the stack trace (1 frame is always better
// than 0!).
// 1-frame stacks don't normally happen, but this depends on the actual
// unwinder implementation (libgcc, libunwind, etc) which is outside of our
// control.
if (to_pop == 0 && size > 1)
to_pop = 1;
PopStackFrames(to_pop);
trace_buffer[0] = pc;
}
void BufferedStackTrace::UnwindSlow(uptr pc, void *context, u32 max_depth) {
CHECK(context);
CHECK_GE(max_depth, 2);
if (!unwind_backtrace_signal_arch) {
UnwindSlow(pc, max_depth);
return;
}
void *map = acquire_my_map_info_list();
CHECK(map);
InternalMmapVector<backtrace_frame_t> frames(kStackTraceMax);
// siginfo argument appears to be unused.
sptr res = unwind_backtrace_signal_arch(/* siginfo */ 0, context, map,
frames.data(),
/* ignore_depth */ 0, max_depth);
release_my_map_info_list(map);
if (res < 0) return;
CHECK_LE((uptr)res, kStackTraceMax);
size = 0;
// +2 compensate for libcorkscrew unwinder returning addresses of call
// instructions instead of raw return addresses.
for (sptr i = 0; i < res; ++i)
trace_buffer[size++] = frames[i].absolute_pc + 2;
}
} // namespace __sanitizer
#endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||
// SANITIZER_SOLARIS
|
