blob: 95da513e66cfa945621c7d8c2ebf3415bd192493 [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/debug/stack_trace.h"
#include <windows.h>
#include <dbghelp.h>
#include <stddef.h>
#include <iostream>
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/singleton.h"
#include "base/process/launch.h"
#include "base/strings/string_util.h"
#include "base/synchronization/lock.h"
#include "base/win/windows_version.h"
namespace base {
namespace debug {
namespace {
// Previous unhandled filter. Will be called if not NULL when we intercept an
// exception. Only used in unit tests.
LPTOP_LEVEL_EXCEPTION_FILTER g_previous_filter = NULL;
bool g_initialized_symbols = false;
DWORD g_init_error = ERROR_SUCCESS;
// Prints the exception call stack.
// This is the unit tests exception filter.
long WINAPI StackDumpExceptionFilter(EXCEPTION_POINTERS* info) {
debug::StackTrace(info).Print();
if (g_previous_filter)
return g_previous_filter(info);
return EXCEPTION_CONTINUE_SEARCH;
}
FilePath GetExePath() {
wchar_t system_buffer[MAX_PATH];
GetModuleFileName(NULL, system_buffer, MAX_PATH);
system_buffer[MAX_PATH - 1] = L'\0';
return FilePath(system_buffer);
}
bool InitializeSymbols() {
if (g_initialized_symbols)
return g_init_error == ERROR_SUCCESS;
g_initialized_symbols = true;
// Defer symbol load until they're needed, use undecorated names, and get line
// numbers.
SymSetOptions(SYMOPT_DEFERRED_LOADS |
SYMOPT_UNDNAME |
SYMOPT_LOAD_LINES);
if (!SymInitialize(GetCurrentProcess(), NULL, TRUE)) {
g_init_error = GetLastError();
// TODO(awong): Handle error: SymInitialize can fail with
// ERROR_INVALID_PARAMETER.
// When it fails, we should not call debugbreak since it kills the current
// process (prevents future tests from running or kills the browser
// process).
DLOG(ERROR) << "SymInitialize failed: " << g_init_error;
return false;
}
// When transferring the binaries e.g. between bots, path put
// into the executable will get off. To still retrieve symbols correctly,
// add the directory of the executable to symbol search path.
// All following errors are non-fatal.
const size_t kSymbolsArraySize = 1024;
std::unique_ptr<wchar_t[]> symbols_path(new wchar_t[kSymbolsArraySize]);
// Note: The below function takes buffer size as number of characters,
// not number of bytes!
if (!SymGetSearchPathW(GetCurrentProcess(),
symbols_path.get(),
kSymbolsArraySize)) {
g_init_error = GetLastError();
DLOG(WARNING) << "SymGetSearchPath failed: " << g_init_error;
return false;
}
std::wstring new_path(std::wstring(symbols_path.get()) +
L";" + GetExePath().DirName().value());
if (!SymSetSearchPathW(GetCurrentProcess(), new_path.c_str())) {
g_init_error = GetLastError();
DLOG(WARNING) << "SymSetSearchPath failed." << g_init_error;
return false;
}
g_init_error = ERROR_SUCCESS;
return true;
}
// SymbolContext is a threadsafe singleton that wraps the DbgHelp Sym* family
// of functions. The Sym* family of functions may only be invoked by one
// thread at a time. SymbolContext code may access a symbol server over the
// network while holding the lock for this singleton. In the case of high
// latency, this code will adversely affect performance.
//
// There is also a known issue where this backtrace code can interact
// badly with breakpad if breakpad is invoked in a separate thread while
// we are using the Sym* functions. This is because breakpad does now
// share a lock with this function. See this related bug:
//
// http://code.google.com/p/google-breakpad/issues/detail?id=311
//
// This is a very unlikely edge case, and the current solution is to
// just ignore it.
class SymbolContext {
public:
static SymbolContext* GetInstance() {
// We use a leaky singleton because code may call this during process
// termination.
return
Singleton<SymbolContext, LeakySingletonTraits<SymbolContext> >::get();
}
// For the given trace, attempts to resolve the symbols, and output a trace
// to the ostream os. The format for each line of the backtrace is:
//
// <tab>SymbolName[0xAddress+Offset] (FileName:LineNo)
//
// This function should only be called if Init() has been called. We do not
// LOG(FATAL) here because this code is called might be triggered by a
// LOG(FATAL) itself. Also, it should not be calling complex code that is
// extensible like PathService since that can in turn fire CHECKs.
void OutputTraceToStream(const void* const* trace,
size_t count,
std::ostream* os) {
base::AutoLock lock(lock_);
for (size_t i = 0; (i < count) && os->good(); ++i) {
const int kMaxNameLength = 256;
DWORD_PTR frame = reinterpret_cast<DWORD_PTR>(trace[i]);
// Code adapted from MSDN example:
// http://msdn.microsoft.com/en-us/library/ms680578(VS.85).aspx
ULONG64 buffer[
(sizeof(SYMBOL_INFO) +
kMaxNameLength * sizeof(wchar_t) +
sizeof(ULONG64) - 1) /
sizeof(ULONG64)];
memset(buffer, 0, sizeof(buffer));
// Initialize symbol information retrieval structures.
DWORD64 sym_displacement = 0;
PSYMBOL_INFO symbol = reinterpret_cast<PSYMBOL_INFO>(&buffer[0]);
symbol->SizeOfStruct = sizeof(SYMBOL_INFO);
symbol->MaxNameLen = kMaxNameLength - 1;
BOOL has_symbol = SymFromAddr(GetCurrentProcess(), frame,
&sym_displacement, symbol);
// Attempt to retrieve line number information.
DWORD line_displacement = 0;
IMAGEHLP_LINE64 line = {};
line.SizeOfStruct = sizeof(IMAGEHLP_LINE64);
BOOL has_line = SymGetLineFromAddr64(GetCurrentProcess(), frame,
&line_displacement, &line);
// Output the backtrace line.
(*os) << "\t";
if (has_symbol) {
(*os) << symbol->Name << " [0x" << trace[i] << "+"
<< sym_displacement << "]";
} else {
// If there is no symbol information, add a spacer.
(*os) << "(No symbol) [0x" << trace[i] << "]";
}
if (has_line) {
(*os) << " (" << line.FileName << ":" << line.LineNumber << ")";
}
(*os) << "\n";
}
}
private:
friend struct DefaultSingletonTraits<SymbolContext>;
SymbolContext() {
InitializeSymbols();
}
base::Lock lock_;
DISALLOW_COPY_AND_ASSIGN(SymbolContext);
};
} // namespace
bool EnableInProcessStackDumping() {
// Add stack dumping support on exception on windows. Similar to OS_POSIX
// signal() handling in process_util_posix.cc.
g_previous_filter = SetUnhandledExceptionFilter(&StackDumpExceptionFilter);
// Need to initialize symbols early in the process or else this fails on
// swarming (since symbols are in different directory than in the exes) and
// also release x64.
return InitializeSymbols();
}
// Disable optimizations for the StackTrace::StackTrace function. It is
// important to disable at least frame pointer optimization ("y"), since
// that breaks CaptureStackBackTrace() and prevents StackTrace from working
// in Release builds (it may still be janky if other frames are using FPO,
// but at least it will make it further).
#if defined(COMPILER_MSVC)
#pragma optimize("", off)
#endif
StackTrace::StackTrace() {
// When walking our own stack, use CaptureStackBackTrace().
count_ = CaptureStackBackTrace(0, arraysize(trace_), trace_, NULL);
}
#if defined(COMPILER_MSVC)
#pragma optimize("", on)
#endif
StackTrace::StackTrace(EXCEPTION_POINTERS* exception_pointers) {
InitTrace(exception_pointers->ContextRecord);
}
StackTrace::StackTrace(const CONTEXT* context) {
InitTrace(context);
}
void StackTrace::InitTrace(const CONTEXT* context_record) {
// StackWalk64 modifies the register context in place, so we have to copy it
// so that downstream exception handlers get the right context. The incoming
// context may have had more register state (YMM, etc) than we need to unwind
// the stack. Typically StackWalk64 only needs integer and control registers.
CONTEXT context_copy;
memcpy(&context_copy, context_record, sizeof(context_copy));
context_copy.ContextFlags = CONTEXT_INTEGER | CONTEXT_CONTROL;
// When walking an exception stack, we need to use StackWalk64().
count_ = 0;
// Initialize stack walking.
STACKFRAME64 stack_frame;
memset(&stack_frame, 0, sizeof(stack_frame));
#if defined(_WIN64)
int machine_type = IMAGE_FILE_MACHINE_AMD64;
stack_frame.AddrPC.Offset = context_record->Rip;
stack_frame.AddrFrame.Offset = context_record->Rbp;
stack_frame.AddrStack.Offset = context_record->Rsp;
#else
int machine_type = IMAGE_FILE_MACHINE_I386;
stack_frame.AddrPC.Offset = context_record->Eip;
stack_frame.AddrFrame.Offset = context_record->Ebp;
stack_frame.AddrStack.Offset = context_record->Esp;
#endif
stack_frame.AddrPC.Mode = AddrModeFlat;
stack_frame.AddrFrame.Mode = AddrModeFlat;
stack_frame.AddrStack.Mode = AddrModeFlat;
while (StackWalk64(machine_type,
GetCurrentProcess(),
GetCurrentThread(),
&stack_frame,
&context_copy,
NULL,
&SymFunctionTableAccess64,
&SymGetModuleBase64,
NULL) &&
count_ < arraysize(trace_)) {
trace_[count_++] = reinterpret_cast<void*>(stack_frame.AddrPC.Offset);
}
for (size_t i = count_; i < arraysize(trace_); ++i)
trace_[i] = NULL;
}
void StackTrace::Print() const {
OutputToStream(&std::cerr);
}
void StackTrace::OutputToStream(std::ostream* os) const {
SymbolContext* context = SymbolContext::GetInstance();
if (g_init_error != ERROR_SUCCESS) {
(*os) << "Error initializing symbols (" << g_init_error
<< "). Dumping unresolved backtrace:\n";
for (size_t i = 0; (i < count_) && os->good(); ++i) {
(*os) << "\t" << trace_[i] << "\n";
}
} else {
(*os) << "Backtrace:\n";
context->OutputTraceToStream(trace_, count_, os);
}
}
} // namespace debug
} // namespace base