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
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
|
// Copyright 2021 The Abseil Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef Y_ABSL_DEBUGGING_INTERNAL_STACKTRACE_RISCV_INL_H_
#define Y_ABSL_DEBUGGING_INTERNAL_STACKTRACE_RISCV_INL_H_
// Generate stack trace for riscv
#include <sys/ucontext.h>
#include "y_absl/base/config.h"
#if defined(__linux__)
#include <sys/mman.h>
#include <ucontext.h>
#include <unistd.h>
#endif
#include <atomic>
#include <cassert>
#include <cstdint>
#include <iostream>
#include "y_absl/base/attributes.h"
#include "y_absl/debugging/internal/address_is_readable.h"
#include "y_absl/debugging/internal/vdso_support.h"
#include "y_absl/debugging/stacktrace.h"
static const uintptr_t kUnknownFrameSize = 0;
#if defined(__linux__)
// Returns the address of the VDSO __kernel_rt_sigreturn function, if present.
static const unsigned char *GetKernelRtSigreturnAddress() {
constexpr uintptr_t kImpossibleAddress = 0;
Y_ABSL_CONST_INIT static std::atomic<uintptr_t> memoized(kImpossibleAddress);
uintptr_t address = memoized.load(std::memory_order_relaxed);
if (address != kImpossibleAddress) {
return reinterpret_cast<const unsigned char *>(address);
}
address = reinterpret_cast<uintptr_t>(nullptr);
#if Y_ABSL_HAVE_VDSO_SUPPORT
y_absl::debugging_internal::VDSOSupport vdso;
if (vdso.IsPresent()) {
y_absl::debugging_internal::VDSOSupport::SymbolInfo symbol_info;
// Symbol versioning pulled from arch/riscv/kernel/vdso/vdso.lds at v5.10.
auto lookup = [&](int type) {
return vdso.LookupSymbol("__kernel_rt_sigreturn", "LINUX_4.15", type,
&symbol_info);
};
if ((!lookup(STT_FUNC) && !lookup(STT_NOTYPE)) ||
symbol_info.address == nullptr) {
// Unexpected: VDSO is present, yet the expected symbol is missing or
// null.
assert(false && "VDSO is present, but doesn't have expected symbol");
} else {
if (reinterpret_cast<uintptr_t>(symbol_info.address) !=
kImpossibleAddress) {
address = reinterpret_cast<uintptr_t>(symbol_info.address);
} else {
assert(false && "VDSO returned invalid address");
}
}
}
#endif
memoized.store(address, std::memory_order_relaxed);
return reinterpret_cast<const unsigned char *>(address);
}
#endif // __linux__
// Compute the size of a stack frame in [low..high). We assume that low < high.
// Return size of kUnknownFrameSize.
template <typename T>
static inline uintptr_t ComputeStackFrameSize(const T *low, const T *high) {
const char *low_char_ptr = reinterpret_cast<const char *>(low);
const char *high_char_ptr = reinterpret_cast<const char *>(high);
return low < high ? high_char_ptr - low_char_ptr : kUnknownFrameSize;
}
// Given a pointer to a stack frame, locate and return the calling stackframe,
// or return null if no stackframe can be found. Perform sanity checks (the
// strictness of which is controlled by the boolean parameter
// "STRICT_UNWINDING") to reduce the chance that a bad pointer is returned.
template <bool STRICT_UNWINDING, bool WITH_CONTEXT>
Y_ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
Y_ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static void ** NextStackFrame(void **old_frame_pointer, const void *uc) {
// .
// .
// .
// +-> +----------------+
// | | return address |
// | | previous fp |
// | | ... |
// | +----------------+ <-+
// | | return address | |
// +---|- previous fp | |
// | ... | |
// $fp ->|----------------+ |
// | return address | |
// | previous fp -|---+
// $sp ->| ... |
// +----------------+
void **new_frame_pointer = reinterpret_cast<void **>(old_frame_pointer[-2]);
bool check_frame_size = true;
#if defined(__linux__)
if (WITH_CONTEXT && uc != nullptr) {
// Check to see if next frame's return address is __kernel_rt_sigreturn.
if (old_frame_pointer[-1] == GetKernelRtSigreturnAddress()) {
const ucontext_t *ucv = static_cast<const ucontext_t *>(uc);
// old_frame_pointer is not suitable for unwinding, look at ucontext to
// discover frame pointer before signal.
//
// RISCV ELF psABI has the frame pointer at x8/fp/s0.
// -- RISCV psABI Table 18.2
void **const pre_signal_frame_pointer =
reinterpret_cast<void **>(ucv->uc_mcontext.__gregs[8]);
// Check the alleged frame pointer is actually readable. This is to
// prevent "double fault" in case we hit the first fault due to stack
// corruption.
if (!y_absl::debugging_internal::AddressIsReadable(
pre_signal_frame_pointer))
return nullptr;
// Alleged frame pointer is readable, use it for further unwinding.
new_frame_pointer = pre_signal_frame_pointer;
// Skip frame size check if we return from a signal. We may be using an
// alterate stack for signals.
check_frame_size = false;
}
}
#endif
// The RISCV ELF psABI mandates that the stack pointer is always 16-byte
// aligned.
// FIXME(abdulras) this doesn't hold for ILP32E which only mandates a 4-byte
// alignment.
if ((reinterpret_cast<uintptr_t>(new_frame_pointer) & 15) != 0)
return nullptr;
// Check frame size. In strict mode, we assume frames to be under 100,000
// bytes. In non-strict mode, we relax the limit to 1MB.
if (check_frame_size) {
const uintptr_t max_size = STRICT_UNWINDING ? 100000 : 1000000;
const uintptr_t frame_size =
ComputeStackFrameSize(old_frame_pointer, new_frame_pointer);
if (frame_size == kUnknownFrameSize || frame_size > max_size)
return nullptr;
}
return new_frame_pointer;
}
template <bool IS_STACK_FRAMES, bool IS_WITH_CONTEXT>
Y_ABSL_ATTRIBUTE_NO_SANITIZE_ADDRESS // May read random elements from stack.
Y_ABSL_ATTRIBUTE_NO_SANITIZE_MEMORY // May read random elements from stack.
static int UnwindImpl(void **result, int *sizes, int max_depth, int skip_count,
const void *ucp, int *min_dropped_frames) {
#if defined(__GNUC__)
void **frame_pointer = reinterpret_cast<void **>(__builtin_frame_address(0));
#else
#error reading stack pointer not yet supported on this platform
#endif
skip_count++; // Skip the frame for this function.
int n = 0;
// The `frame_pointer` that is computed here points to the top of the frame.
// The two words preceding the address are the return address and the previous
// frame pointer. To find a PC value associated with the current frame, we
// need to go down a level in the call chain. So we remember the return
// address of the last frame seen. This does not work for the first stack
// frame, which belongs to `UnwindImp()` but we skip the frame for
// `UnwindImp()` anyway.
void *prev_return_address = nullptr;
while (frame_pointer && n < max_depth) {
// The y_absl::GetStackFrames routine si called when we are in some
// informational context (the failure signal handler for example). Use the
// non-strict unwinding rules to produce a stack trace that is as complete
// as possible (even if it contains a few bogus entries in some rare cases).
void **next_frame_pointer =
NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
if (skip_count > 0) {
skip_count--;
} else {
result[n] = prev_return_address;
if (IS_STACK_FRAMES) {
sizes[n] = ComputeStackFrameSize(frame_pointer, next_frame_pointer);
}
n++;
}
prev_return_address = frame_pointer[-1];
frame_pointer = next_frame_pointer;
}
if (min_dropped_frames != nullptr) {
// Implementation detail: we clamp the max of frames we are willing to
// count, so as not to spend too much time in the loop below.
const int kMaxUnwind = 200;
int j = 0;
for (; frame_pointer != nullptr && j < kMaxUnwind; j++) {
frame_pointer =
NextStackFrame<!IS_STACK_FRAMES, IS_WITH_CONTEXT>(frame_pointer, ucp);
}
*min_dropped_frames = j;
}
return n;
}
namespace y_absl {
Y_ABSL_NAMESPACE_BEGIN
namespace debugging_internal {
bool StackTraceWorksForTest() { return true; }
} // namespace debugging_internal
Y_ABSL_NAMESPACE_END
} // namespace y_absl
#endif
|
