examine_stack.cc
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1 //
2 // Copyright 2018 The Abseil Authors.
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 //
8 // https://www.apache.org/licenses/LICENSE-2.0
9 //
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
15 //
16 
18 
19 #ifndef _WIN32
20 #include <unistd.h>
21 #endif
22 
23 #include <csignal>
24 #include <cstdio>
25 
26 #include "absl/base/attributes.h"
28 #include "absl/base/macros.h"
31 
32 namespace absl {
33 namespace debugging_internal {
34 
35 // Returns the program counter from signal context, nullptr if
36 // unknown. vuc is a ucontext_t*. We use void* to avoid the use of
37 // ucontext_t on non-POSIX systems.
38 void* GetProgramCounter(void* vuc) {
39 #ifdef __linux__
40  if (vuc != nullptr) {
41  ucontext_t* context = reinterpret_cast<ucontext_t*>(vuc);
42 #if defined(__aarch64__)
43  return reinterpret_cast<void*>(context->uc_mcontext.pc);
44 #elif defined(__arm__)
45  return reinterpret_cast<void*>(context->uc_mcontext.arm_pc);
46 #elif defined(__i386__)
47  if (14 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs))
48  return reinterpret_cast<void*>(context->uc_mcontext.gregs[14]);
49 #elif defined(__mips__)
50  return reinterpret_cast<void*>(context->uc_mcontext.pc);
51 #elif defined(__powerpc64__)
52  return reinterpret_cast<void*>(context->uc_mcontext.gp_regs[32]);
53 #elif defined(__powerpc__)
54  return reinterpret_cast<void*>(context->uc_mcontext.regs->nip);
55 #elif defined(__s390__) && !defined(__s390x__)
56  return reinterpret_cast<void*>(context->uc_mcontext.psw.addr & 0x7fffffff);
57 #elif defined(__s390__) && defined(__s390x__)
58  return reinterpret_cast<void*>(context->uc_mcontext.psw.addr);
59 #elif defined(__x86_64__)
60  if (16 < ABSL_ARRAYSIZE(context->uc_mcontext.gregs))
61  return reinterpret_cast<void*>(context->uc_mcontext.gregs[16]);
62 #else
63 #error "Undefined Architecture."
64 #endif
65  }
66 #elif defined(__akaros__)
67  auto* ctx = reinterpret_cast<struct user_context*>(vuc);
68  return reinterpret_cast<void*>(get_user_ctx_pc(ctx));
69 #endif
70  static_cast<void>(vuc);
71  return nullptr;
72 }
73 
74 // The %p field width for printf() functions is two characters per byte,
75 // and two extra for the leading "0x".
76 static constexpr int kPrintfPointerFieldWidth = 2 + 2 * sizeof(void*);
77 
78 // Print a program counter, its stack frame size, and its symbol name.
79 // Note that there is a separate symbolize_pc argument. Return addresses may be
80 // at the end of the function, and this allows the caller to back up from pc if
81 // appropriate.
82 static void DumpPCAndFrameSizeAndSymbol(void (*writerfn)(const char*, void*),
83  void* writerfn_arg, void* pc,
84  void* symbolize_pc, int framesize,
85  const char* const prefix) {
86  char tmp[1024];
87  const char* symbol = "(unknown)";
88  if (absl::Symbolize(symbolize_pc, tmp, sizeof(tmp))) {
89  symbol = tmp;
90  }
91  char buf[1024];
92  if (framesize <= 0) {
93  snprintf(buf, sizeof(buf), "%s@ %*p (unknown) %s\n", prefix,
94  kPrintfPointerFieldWidth, pc, symbol);
95  } else {
96  snprintf(buf, sizeof(buf), "%s@ %*p %9d %s\n", prefix,
97  kPrintfPointerFieldWidth, pc, framesize, symbol);
98  }
99  writerfn(buf, writerfn_arg);
100 }
101 
102 // Print a program counter and the corresponding stack frame size.
103 static void DumpPCAndFrameSize(void (*writerfn)(const char*, void*),
104  void* writerfn_arg, void* pc, int framesize,
105  const char* const prefix) {
106  char buf[100];
107  if (framesize <= 0) {
108  snprintf(buf, sizeof(buf), "%s@ %*p (unknown)\n", prefix,
109  kPrintfPointerFieldWidth, pc);
110  } else {
111  snprintf(buf, sizeof(buf), "%s@ %*p %9d\n", prefix,
112  kPrintfPointerFieldWidth, pc, framesize);
113  }
114  writerfn(buf, writerfn_arg);
115 }
116 
118  void* pc, void* const stack[], int frame_sizes[], int depth,
119  int min_dropped_frames, bool symbolize_stacktrace,
120  void (*writerfn)(const char*, void*), void* writerfn_arg) {
121  if (pc != nullptr) {
122  // We don't know the stack frame size for PC, use 0.
123  if (symbolize_stacktrace) {
124  DumpPCAndFrameSizeAndSymbol(writerfn, writerfn_arg, pc, pc, 0, "PC: ");
125  } else {
126  DumpPCAndFrameSize(writerfn, writerfn_arg, pc, 0, "PC: ");
127  }
128  }
129  for (int i = 0; i < depth; i++) {
130  if (symbolize_stacktrace) {
131  // Pass the previous address of pc as the symbol address because pc is a
132  // return address, and an overrun may occur when the function ends with a
133  // call to a function annotated noreturn (e.g. CHECK). Note that we don't
134  // do this for pc above, as the adjustment is only correct for return
135  // addresses.
136  DumpPCAndFrameSizeAndSymbol(writerfn, writerfn_arg, stack[i],
137  reinterpret_cast<char*>(stack[i]) - 1,
138  frame_sizes[i], " ");
139  } else {
140  DumpPCAndFrameSize(writerfn, writerfn_arg, stack[i], frame_sizes[i],
141  " ");
142  }
143  }
144  if (min_dropped_frames > 0) {
145  char buf[100];
146  snprintf(buf, sizeof(buf), " @ ... and at least %d more frames\n",
147  min_dropped_frames);
148  writerfn(buf, writerfn_arg);
149  }
150 }
151 
152 } // namespace debugging_internal
153 } // namespace absl
static constexpr int kPrintfPointerFieldWidth
static void DumpPCAndFrameSizeAndSymbol(void(*writerfn)(const char *, void *), void *writerfn_arg, void *pc, void *symbolize_pc, int framesize, const char *const prefix)
char buf[N]
Definition: algorithm.h:29
static void DumpPCAndFrameSize(void(*writerfn)(const char *, void *), void *writerfn_arg, void *pc, int framesize, const char *const prefix)
bool Symbolize(const void *pc, char *out, int out_size)
void * stack[40]
Definition: graphcycles.cc:286
#define ABSL_ARRAYSIZE(array)
Definition: macros.h:42
void DumpPCAndFrameSizesAndStackTrace(void *pc, void *const stack[], int frame_sizes[], int depth, int min_dropped_frames, bool symbolize_stacktrace, void(*writerfn)(const char *, void *), void *writerfn_arg)
void * GetProgramCounter(void *vuc)


abseil_cpp
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autogenerated on Mon Feb 28 2022 21:31:18