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gecko-dev/mozglue/misc/StackWalk.cpp

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/* API for getting a stack trace of the C/C++ stack on the current thread */
#include "mozilla/ArrayUtils.h"
#include "mozilla/Assertions.h"
#include "mozilla/IntegerPrintfMacros.h"
#include "mozilla/StackWalk.h"
#include <string.h>
using namespace mozilla;
// for _Unwind_Backtrace from libcxxrt or libunwind
// cxxabi.h from libcxxrt implicitly includes unwind.h first
#if defined(HAVE__UNWIND_BACKTRACE) && !defined(_GNU_SOURCE)
#define _GNU_SOURCE
#endif
#if defined(HAVE_DLOPEN) || defined(XP_DARWIN)
#include <dlfcn.h>
#endif
#if (defined(XP_DARWIN) && \
(defined(__i386) || defined(__ppc__) || defined(HAVE__UNWIND_BACKTRACE)))
#define MOZ_STACKWALK_SUPPORTS_MACOSX 1
#else
#define MOZ_STACKWALK_SUPPORTS_MACOSX 0
#endif
#if (defined(linux) && \
((defined(__GNUC__) && (defined(__i386) || defined(PPC))) || \
defined(HAVE__UNWIND_BACKTRACE)))
#define MOZ_STACKWALK_SUPPORTS_LINUX 1
#else
#define MOZ_STACKWALK_SUPPORTS_LINUX 0
#endif
#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 1)
#define HAVE___LIBC_STACK_END 1
#else
#define HAVE___LIBC_STACK_END 0
#endif
#if HAVE___LIBC_STACK_END
extern MOZ_EXPORT void* __libc_stack_end; // from ld-linux.so
#endif
#ifdef ANDROID
#include <algorithm>
#include <unistd.h>
#include <pthread.h>
#endif
#if MOZ_STACKWALK_SUPPORTS_WINDOWS
#include <windows.h>
#include <process.h>
#include <stdio.h>
#include <malloc.h>
#include "mozilla/ArrayUtils.h"
#include "mozilla/Atomics.h"
#include "mozilla/StackWalk_windows.h"
#include "mozilla/WindowsVersion.h"
#include <imagehlp.h>
// We need a way to know if we are building for WXP (or later), as if we are, we
// need to use the newer 64-bit APIs. API_VERSION_NUMBER seems to fit the bill.
// A value of 9 indicates we want to use the new APIs.
#if API_VERSION_NUMBER < 9
#error Too old imagehlp.h
#endif
struct WalkStackData
{
// Are we walking the stack of the calling thread? Note that we need to avoid
// calling fprintf and friends if this is false, in order to avoid deadlocks.
bool walkCallingThread;
uint32_t skipFrames;
HANDLE thread;
HANDLE process;
HANDLE eventStart;
HANDLE eventEnd;
void** pcs;
uint32_t pc_size;
uint32_t pc_count;
uint32_t pc_max;
void** sps;
uint32_t sp_size;
uint32_t sp_count;
CONTEXT* context;
};
CRITICAL_SECTION gDbgHelpCS;
#ifdef _M_AMD64
// Because various Win64 APIs acquire function-table locks, we need a way of
// preventing stack walking while those APIs are being called. Otherwise, the
// stack walker may suspend a thread holding such a lock, and deadlock when the
// stack unwind code attempts to wait for that lock.
//
// We're using an atomic counter rather than a critical section because we
// don't require mutual exclusion with the stack walker. If the stack walker
// determines that it's safe to start unwinding the suspended thread (i.e.
// there are no suppressions when the unwind begins), then it's safe to
// continue unwinding that thread even if other threads request suppressions
// in the meantime, because we can't deadlock with those other threads.
//
// XXX: This global variable is a larger-than-necessary hammer. A more scoped
// solution would be to maintain a counter per thread, but then it would be
// more difficult for WalkStackMain64 to read the suspended thread's counter.
static Atomic<size_t> sStackWalkSuppressions;
MFBT_API
AutoSuppressStackWalking::AutoSuppressStackWalking()
{
++sStackWalkSuppressions;
}
MFBT_API
AutoSuppressStackWalking::~AutoSuppressStackWalking()
{
--sStackWalkSuppressions;
}
static uint8_t* sJitCodeRegionStart;
static size_t sJitCodeRegionSize;
uint8_t* sMsMpegJitCodeRegionStart;
size_t sMsMpegJitCodeRegionSize;
MFBT_API void
RegisterJitCodeRegion(uint8_t* aStart, size_t aSize)
{
// Currently we can only handle one JIT code region at a time
MOZ_RELEASE_ASSERT(!sJitCodeRegionStart);
sJitCodeRegionStart = aStart;
sJitCodeRegionSize = aSize;
}
MFBT_API void
UnregisterJitCodeRegion(uint8_t* aStart, size_t aSize)
{
// Currently we can only handle one JIT code region at a time
MOZ_RELEASE_ASSERT(sJitCodeRegionStart &&
sJitCodeRegionStart == aStart &&
sJitCodeRegionSize == aSize);
sJitCodeRegionStart = nullptr;
sJitCodeRegionSize = 0;
}
#endif // _M_AMD64
// Routine to print an error message to standard error.
static void
PrintError(const char* aPrefix)
{
LPSTR lpMsgBuf;
DWORD lastErr = GetLastError();
FormatMessageA(
FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
nullptr,
lastErr,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
(LPSTR)&lpMsgBuf,
0,
nullptr
);
fprintf(stderr, "### ERROR: %s: %s",
aPrefix, lpMsgBuf ? lpMsgBuf : "(null)\n");
fflush(stderr);
LocalFree(lpMsgBuf);
}
static void
InitializeDbgHelpCriticalSection()
{
static bool initialized = false;
if (initialized) {
return;
}
::InitializeCriticalSection(&gDbgHelpCS);
initialized = true;
}
static void
WalkStackMain64(struct WalkStackData* aData)
{
// Get a context for the specified thread.
CONTEXT context_buf;
CONTEXT* context;
if (!aData->context) {
context = &context_buf;
memset(context, 0, sizeof(CONTEXT));
context->ContextFlags = CONTEXT_FULL;
if (aData->walkCallingThread) {
::RtlCaptureContext(context);
} else if (!GetThreadContext(aData->thread, context)) {
return;
}
} else {
context = aData->context;
}
#if defined(_M_IX86) || defined(_M_IA64)
// Setup initial stack frame to walk from.
STACKFRAME64 frame64;
memset(&frame64, 0, sizeof(frame64));
#ifdef _M_IX86
frame64.AddrPC.Offset = context->Eip;
frame64.AddrStack.Offset = context->Esp;
frame64.AddrFrame.Offset = context->Ebp;
#elif defined _M_IA64
frame64.AddrPC.Offset = context->StIIP;
frame64.AddrStack.Offset = context->SP;
frame64.AddrFrame.Offset = context->RsBSP;
#endif
frame64.AddrPC.Mode = AddrModeFlat;
frame64.AddrStack.Mode = AddrModeFlat;
frame64.AddrFrame.Mode = AddrModeFlat;
frame64.AddrReturn.Mode = AddrModeFlat;
#endif
#ifdef _WIN64
// If there are any active suppressions, then at least one thread (we don't
// know which) is holding a lock that can deadlock RtlVirtualUnwind. Since
// that thread may be the one that we're trying to unwind, we can't proceed.
//
// But if there are no suppressions, then our target thread can't be holding
// a lock, and it's safe to proceed. By virtue of being suspended, the target
// thread can't acquire any new locks during the unwind process, so we only
// need to do this check once. After that, sStackWalkSuppressions can be
// changed by other threads while we're unwinding, and that's fine because
// we can't deadlock with those threads.
if (sStackWalkSuppressions) {
return;
}
#endif
#ifdef _M_AMD64
bool firstFrame = true;
#endif
// Skip our own stack walking frames.
int skip = (aData->walkCallingThread ? 3 : 0) + aData->skipFrames;
// Now walk the stack.
while (true) {
DWORD64 addr;
DWORD64 spaddr;
#if defined(_M_IX86) || defined(_M_IA64)
// 32-bit frame unwinding.
// Debug routines are not threadsafe, so grab the lock.
EnterCriticalSection(&gDbgHelpCS);
BOOL ok = StackWalk64(
#if defined _M_IA64
IMAGE_FILE_MACHINE_IA64,
#elif defined _M_IX86
IMAGE_FILE_MACHINE_I386,
#endif
aData->process,
aData->thread,
&frame64,
context,
nullptr,
SymFunctionTableAccess64, // function table access routine
SymGetModuleBase64, // module base routine
0
);
LeaveCriticalSection(&gDbgHelpCS);
if (ok) {
addr = frame64.AddrPC.Offset;
spaddr = frame64.AddrStack.Offset;
} else {
addr = 0;
spaddr = 0;
if (aData->walkCallingThread) {
PrintError("WalkStack64");
}
}
if (!ok) {
break;
}
#elif defined(_M_AMD64)
// If we reach a frame in JIT code, we don't have enough information to
// unwind, so we have to give up.
if (sJitCodeRegionStart &&
(uint8_t*)context->Rip >= sJitCodeRegionStart &&
(uint8_t*)context->Rip < sJitCodeRegionStart + sJitCodeRegionSize) {
break;
}
// We must also avoid msmpeg2vdec.dll's JIT region: they don't generate
// unwind data, so their JIT unwind callback just throws up its hands and
// terminates the process.
if (sMsMpegJitCodeRegionStart &&
(uint8_t*)context->Rip >= sMsMpegJitCodeRegionStart &&
(uint8_t*)context->Rip < sMsMpegJitCodeRegionStart + sMsMpegJitCodeRegionSize) {
break;
}
// 64-bit frame unwinding.
// Try to look up unwind metadata for the current function.
ULONG64 imageBase;
PRUNTIME_FUNCTION runtimeFunction =
RtlLookupFunctionEntry(context->Rip, &imageBase, NULL);
if (runtimeFunction) {
PVOID dummyHandlerData;
ULONG64 dummyEstablisherFrame;
RtlVirtualUnwind(UNW_FLAG_NHANDLER,
imageBase,
context->Rip,
runtimeFunction,
context,
&dummyHandlerData,
&dummyEstablisherFrame,
nullptr);
} else if (firstFrame) {
// Leaf functions can be unwound by hand.
context->Rip = *reinterpret_cast<DWORD64*>(context->Rsp);
context->Rsp += sizeof(void*);
} else {
// Something went wrong.
break;
}
addr = context->Rip;
spaddr = context->Rsp;
firstFrame = false;
#else
#error "unknown platform"
#endif
if (addr == 0) {
break;
}
if (skip-- > 0) {
continue;
}
if (aData->pc_count < aData->pc_size) {
aData->pcs[aData->pc_count] = (void*)addr;
}
++aData->pc_count;
if (aData->sp_count < aData->sp_size) {
aData->sps[aData->sp_count] = (void*)spaddr;
}
++aData->sp_count;
if (aData->pc_max != 0 && aData->pc_count == aData->pc_max) {
break;
}
#if defined(_M_IX86) || defined(_M_IA64)
if (frame64.AddrReturn.Offset == 0) {
break;
}
#endif
}
}
/**
* Walk the stack, translating PC's found into strings and recording the
* chain in aBuffer. For this to work properly, the DLLs must be rebased
* so that the address in the file agrees with the address in memory.
* Otherwise StackWalk will return FALSE when it hits a frame in a DLL
* whose in memory address doesn't match its in-file address.
*/
MFBT_API void
MozStackWalkThread(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure,
HANDLE aThread, CONTEXT* aContext)
{
static HANDLE myProcess = nullptr;
HANDLE myThread;
struct WalkStackData data;
InitializeDbgHelpCriticalSection();
HANDLE targetThread = aThread;
if (!aThread) {
targetThread = ::GetCurrentThread();
data.walkCallingThread = true;
} else {
DWORD threadId = ::GetThreadId(aThread);
DWORD currentThreadId = ::GetCurrentThreadId();
data.walkCallingThread = (threadId == currentThreadId);
}
// Have to duplicate handle to get a real handle.
if (!myProcess) {
if (!::DuplicateHandle(::GetCurrentProcess(),
::GetCurrentProcess(),
::GetCurrentProcess(),
&myProcess,
PROCESS_ALL_ACCESS, FALSE, 0)) {
if (data.walkCallingThread) {
PrintError("DuplicateHandle (process)");
}
return;
}
}
if (!::DuplicateHandle(::GetCurrentProcess(),
targetThread,
::GetCurrentProcess(),
&myThread,
THREAD_ALL_ACCESS, FALSE, 0)) {
if (data.walkCallingThread) {
PrintError("DuplicateHandle (thread)");
}
return;
}
data.skipFrames = aSkipFrames;
data.thread = myThread;
data.process = myProcess;
void* local_pcs[1024];
data.pcs = local_pcs;
data.pc_count = 0;
data.pc_size = ArrayLength(local_pcs);
data.pc_max = aMaxFrames;
void* local_sps[1024];
data.sps = local_sps;
data.sp_count = 0;
data.sp_size = ArrayLength(local_sps);
data.context = aContext;
WalkStackMain64(&data);
if (data.pc_count > data.pc_size) {
data.pcs = (void**)_alloca(data.pc_count * sizeof(void*));
data.pc_size = data.pc_count;
data.pc_count = 0;
data.sps = (void**)_alloca(data.sp_count * sizeof(void*));
data.sp_size = data.sp_count;
data.sp_count = 0;
WalkStackMain64(&data);
}
::CloseHandle(myThread);
for (uint32_t i = 0; i < data.pc_count; ++i) {
(*aCallback)(i + 1, data.pcs[i], data.sps[i], aClosure);
}
}
MFBT_API void
MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure)
{
MozStackWalkThread(aCallback, aSkipFrames, aMaxFrames, aClosure,
nullptr, nullptr);
}
static BOOL CALLBACK
callbackEspecial64(
PCSTR aModuleName,
DWORD64 aModuleBase,
ULONG aModuleSize,
PVOID aUserContext)
{
BOOL retval = TRUE;
DWORD64 addr = *(DWORD64*)aUserContext;
/*
* You'll want to control this if we are running on an
* architecture where the addresses go the other direction.
* Not sure this is even a realistic consideration.
*/
const BOOL addressIncreases = TRUE;
/*
* If it falls in side the known range, load the symbols.
*/
if (addressIncreases
? (addr >= aModuleBase && addr <= (aModuleBase + aModuleSize))
: (addr <= aModuleBase && addr >= (aModuleBase - aModuleSize))
) {
retval = !!SymLoadModule64(GetCurrentProcess(), nullptr,
(PSTR)aModuleName, nullptr,
aModuleBase, aModuleSize);
if (!retval) {
PrintError("SymLoadModule64");
}
}
return retval;
}
/*
* SymGetModuleInfoEspecial
*
* Attempt to determine the module information.
* Bug 112196 says this DLL may not have been loaded at the time
* SymInitialize was called, and thus the module information
* and symbol information is not available.
* This code rectifies that problem.
*/
// New members were added to IMAGEHLP_MODULE64 (that show up in the
// Platform SDK that ships with VC8, but not the Platform SDK that ships
// with VC7.1, i.e., between DbgHelp 6.0 and 6.1), but we don't need to
// use them, and it's useful to be able to function correctly with the
// older library. (Stock Windows XP SP2 seems to ship with dbghelp.dll
// version 5.1.) Since Platform SDK version need not correspond to
// compiler version, and the version number in debughlp.h was NOT bumped
// when these changes were made, ifdef based on a constant that was
// added between these versions.
#ifdef SSRVOPT_SETCONTEXT
#define NS_IMAGEHLP_MODULE64_SIZE (((offsetof(IMAGEHLP_MODULE64, LoadedPdbName) + sizeof(DWORD64) - 1) / sizeof(DWORD64)) * sizeof(DWORD64))
#else
#define NS_IMAGEHLP_MODULE64_SIZE sizeof(IMAGEHLP_MODULE64)
#endif
BOOL SymGetModuleInfoEspecial64(HANDLE aProcess, DWORD64 aAddr,
PIMAGEHLP_MODULE64 aModuleInfo,
PIMAGEHLP_LINE64 aLineInfo)
{
BOOL retval = FALSE;
/*
* Init the vars if we have em.
*/
aModuleInfo->SizeOfStruct = NS_IMAGEHLP_MODULE64_SIZE;
if (aLineInfo) {
aLineInfo->SizeOfStruct = sizeof(IMAGEHLP_LINE64);
}
/*
* Give it a go.
* It may already be loaded.
*/
retval = SymGetModuleInfo64(aProcess, aAddr, aModuleInfo);
if (retval == FALSE) {
/*
* Not loaded, here's the magic.
* Go through all the modules.
*/
// Need to cast to PENUMLOADED_MODULES_CALLBACK64 because the
// constness of the first parameter of
// PENUMLOADED_MODULES_CALLBACK64 varies over SDK versions (from
// non-const to const over time). See bug 391848 and bug
// 415426.
BOOL enumRes = EnumerateLoadedModules64(
aProcess,
(PENUMLOADED_MODULES_CALLBACK64)callbackEspecial64,
(PVOID)&aAddr);
if (enumRes != FALSE) {
/*
* One final go.
* If it fails, then well, we have other problems.
*/
retval = SymGetModuleInfo64(aProcess, aAddr, aModuleInfo);
}
}
/*
* If we got module info, we may attempt line info as well.
* We will not report failure if this does not work.
*/
if (retval != FALSE && aLineInfo) {
DWORD displacement = 0;
BOOL lineRes = FALSE;
lineRes = SymGetLineFromAddr64(aProcess, aAddr, &displacement, aLineInfo);
if (!lineRes) {
// Clear out aLineInfo to indicate that it's not valid
memset(aLineInfo, 0, sizeof(*aLineInfo));
}
}
return retval;
}
static bool
EnsureSymInitialized()
{
static bool gInitialized = false;
bool retStat;
if (gInitialized) {
return gInitialized;
}
InitializeDbgHelpCriticalSection();
SymSetOptions(SYMOPT_LOAD_LINES | SYMOPT_UNDNAME);
retStat = SymInitialize(GetCurrentProcess(), nullptr, TRUE);
if (!retStat) {
PrintError("SymInitialize");
}
gInitialized = retStat;
/* XXX At some point we need to arrange to call SymCleanup */
return retStat;
}
MFBT_API bool
MozDescribeCodeAddress(void* aPC, MozCodeAddressDetails* aDetails)
{
aDetails->library[0] = '\0';
aDetails->loffset = 0;
aDetails->filename[0] = '\0';
aDetails->lineno = 0;
aDetails->function[0] = '\0';
aDetails->foffset = 0;
if (!EnsureSymInitialized()) {
return false;
}
HANDLE myProcess = ::GetCurrentProcess();
BOOL ok;
// debug routines are not threadsafe, so grab the lock.
EnterCriticalSection(&gDbgHelpCS);
//
// Attempt to load module info before we attempt to resolve the symbol.
// This just makes sure we get good info if available.
//
DWORD64 addr = (DWORD64)aPC;
IMAGEHLP_MODULE64 modInfo;
IMAGEHLP_LINE64 lineInfo;
BOOL modInfoRes;
modInfoRes = SymGetModuleInfoEspecial64(myProcess, addr, &modInfo, &lineInfo);
if (modInfoRes) {
strncpy(aDetails->library, modInfo.LoadedImageName,
sizeof(aDetails->library));
aDetails->library[mozilla::ArrayLength(aDetails->library) - 1] = '\0';
aDetails->loffset = (char*)aPC - (char*)modInfo.BaseOfImage;
if (lineInfo.FileName) {
strncpy(aDetails->filename, lineInfo.FileName,
sizeof(aDetails->filename));
aDetails->filename[mozilla::ArrayLength(aDetails->filename) - 1] = '\0';
aDetails->lineno = lineInfo.LineNumber;
}
}
ULONG64 buffer[(sizeof(SYMBOL_INFO) +
MAX_SYM_NAME * sizeof(TCHAR) + sizeof(ULONG64) - 1) / sizeof(ULONG64)];
PSYMBOL_INFO pSymbol = (PSYMBOL_INFO)buffer;
pSymbol->SizeOfStruct = sizeof(SYMBOL_INFO);
pSymbol->MaxNameLen = MAX_SYM_NAME;
DWORD64 displacement;
ok = SymFromAddr(myProcess, addr, &displacement, pSymbol);
if (ok) {
strncpy(aDetails->function, pSymbol->Name,
sizeof(aDetails->function));
aDetails->function[mozilla::ArrayLength(aDetails->function) - 1] = '\0';
aDetails->foffset = static_cast<ptrdiff_t>(displacement);
}
LeaveCriticalSection(&gDbgHelpCS); // release our lock
return true;
}
// i386 or PPC Linux stackwalking code
#elif HAVE_DLADDR && (HAVE__UNWIND_BACKTRACE || MOZ_STACKWALK_SUPPORTS_LINUX || MOZ_STACKWALK_SUPPORTS_MACOSX)
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
// On glibc 2.1, the Dl_info api defined in <dlfcn.h> is only exposed
// if __USE_GNU is defined. I suppose its some kind of standards
// adherence thing.
//
#if (__GLIBC_MINOR__ >= 1) && !defined(__USE_GNU)
#define __USE_GNU
#endif
// This thing is exported by libstdc++
// Yes, this is a gcc only hack
#if defined(MOZ_DEMANGLE_SYMBOLS)
#include <cxxabi.h>
#endif // MOZ_DEMANGLE_SYMBOLS
void DemangleSymbol(const char* aSymbol,
char* aBuffer,
int aBufLen)
{
aBuffer[0] = '\0';
#if defined(MOZ_DEMANGLE_SYMBOLS)
/* See demangle.h in the gcc source for the voodoo */
char* demangled = abi::__cxa_demangle(aSymbol, 0, 0, 0);
if (demangled) {
strncpy(aBuffer, demangled, aBufLen);
aBuffer[aBufLen - 1] = '\0';
free(demangled);
}
#endif // MOZ_DEMANGLE_SYMBOLS
}
// {x86, ppc} x {Linux, Mac} stackwalking code.
#if ((defined(__i386) || defined(PPC) || defined(__ppc__)) && \
(MOZ_STACKWALK_SUPPORTS_MACOSX || MOZ_STACKWALK_SUPPORTS_LINUX))
MFBT_API void
MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure)
{
// Get the frame pointer
void** bp = (void**)__builtin_frame_address(0);
void* stackEnd;
#if HAVE___LIBC_STACK_END
stackEnd = __libc_stack_end;
#elif defined(XP_DARWIN)
stackEnd = pthread_get_stackaddr_np(pthread_self());
#elif defined(ANDROID)
pthread_attr_t sattr;
pthread_attr_init(&sattr);
pthread_getattr_np(pthread_self(), &sattr);
void* stackBase = stackEnd = nullptr;
size_t stackSize = 0;
if (gettid() != getpid()) {
// bionic's pthread_attr_getstack doesn't tell the truth for the main
// thread (see bug 846670). So don't use it for the main thread.
if (!pthread_attr_getstack(&sattr, &stackBase, &stackSize)) {
stackEnd = static_cast<char*>(stackBase) + stackSize;
} else {
stackEnd = nullptr;
}
}
if (!stackEnd) {
// So consider the current frame pointer + an arbitrary size of 8MB
// (modulo overflow ; not really arbitrary as it's the default stack
// size for the main thread) if pthread_attr_getstack failed for
// some reason (or was skipped).
static const uintptr_t kMaxStackSize = 8 * 1024 * 1024;
uintptr_t maxStackStart = uintptr_t(-1) - kMaxStackSize;
uintptr_t stackStart = std::max(maxStackStart, uintptr_t(bp));
stackEnd = reinterpret_cast<void*>(stackStart + kMaxStackSize);
}
#else
# error Unsupported configuration
#endif
FramePointerStackWalk(aCallback, aSkipFrames, aMaxFrames, aClosure, bp,
stackEnd);
}
#elif defined(HAVE__UNWIND_BACKTRACE)
// libgcc_s.so symbols _Unwind_Backtrace@@GCC_3.3 and _Unwind_GetIP@@GCC_3.0
#include <unwind.h>
struct unwind_info
{
MozWalkStackCallback callback;
int skip;
int maxFrames;
int numFrames;
void* closure;
};
static _Unwind_Reason_Code
unwind_callback(struct _Unwind_Context* context, void* closure)
{
unwind_info* info = static_cast<unwind_info*>(closure);
void* pc = reinterpret_cast<void*>(_Unwind_GetIP(context));
// TODO Use something like '_Unwind_GetGR()' to get the stack pointer.
if (--info->skip < 0) {
info->numFrames++;
(*info->callback)(info->numFrames, pc, nullptr, info->closure);
if (info->maxFrames != 0 && info->numFrames == info->maxFrames) {
// Again, any error code that stops the walk will do.
return _URC_FOREIGN_EXCEPTION_CAUGHT;
}
}
return _URC_NO_REASON;
}
MFBT_API void
MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure)
{
unwind_info info;
info.callback = aCallback;
info.skip = aSkipFrames + 1;
info.maxFrames = aMaxFrames;
info.numFrames = 0;
info.closure = aClosure;
// We ignore the return value from _Unwind_Backtrace. There are three main
// reasons for this.
// - On ARM/Android bionic's _Unwind_Backtrace usually (always?) returns
// _URC_FAILURE. See
// https://bugzilla.mozilla.org/show_bug.cgi?id=717853#c110.
// - If aMaxFrames != 0, we want to stop early, and the only way to do that
// is to make unwind_callback return something other than _URC_NO_REASON,
// which causes _Unwind_Backtrace to return a non-success code.
// - MozStackWalk doesn't have a return value anyway.
(void)_Unwind_Backtrace(unwind_callback, &info);
}
#endif
bool MFBT_API
MozDescribeCodeAddress(void* aPC, MozCodeAddressDetails* aDetails)
{
aDetails->library[0] = '\0';
aDetails->loffset = 0;
aDetails->filename[0] = '\0';
aDetails->lineno = 0;
aDetails->function[0] = '\0';
aDetails->foffset = 0;
Dl_info info;
int ok = dladdr(aPC, &info);
if (!ok) {
return true;
}
strncpy(aDetails->library, info.dli_fname, sizeof(aDetails->library));
aDetails->library[mozilla::ArrayLength(aDetails->library) - 1] = '\0';
aDetails->loffset = (char*)aPC - (char*)info.dli_fbase;
const char* symbol = info.dli_sname;
if (!symbol || symbol[0] == '\0') {
return true;
}
DemangleSymbol(symbol, aDetails->function, sizeof(aDetails->function));
if (aDetails->function[0] == '\0') {
// Just use the mangled symbol if demangling failed.
strncpy(aDetails->function, symbol, sizeof(aDetails->function));
aDetails->function[mozilla::ArrayLength(aDetails->function) - 1] = '\0';
}
aDetails->foffset = (char*)aPC - (char*)info.dli_saddr;
return true;
}
#else // unsupported platform.
MFBT_API void
MozStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure)
{
}
MFBT_API bool
MozDescribeCodeAddress(void* aPC, MozCodeAddressDetails* aDetails)
{
aDetails->library[0] = '\0';
aDetails->loffset = 0;
aDetails->filename[0] = '\0';
aDetails->lineno = 0;
aDetails->function[0] = '\0';
aDetails->foffset = 0;
return false;
}
#endif
#if defined(XP_WIN) || defined (XP_MACOSX) || defined (XP_LINUX)
namespace mozilla {
void
FramePointerStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure, void** aBp,
void* aStackEnd)
{
// Stack walking code courtesy Kipp's "leaky".
int32_t skip = aSkipFrames;
uint32_t numFrames = 0;
while (aBp) {
void** next = (void**)*aBp;
// aBp may not be a frame pointer on i386 if code was compiled with
// -fomit-frame-pointer, so do some sanity checks.
// (aBp should be a frame pointer on ppc(64) but checking anyway may help
// a little if the stack has been corrupted.)
// We don't need to check against the begining of the stack because
// we can assume that aBp > sp
if (next <= aBp ||
next > aStackEnd ||
(uintptr_t(next) & 3)) {
break;
}
#if (defined(__ppc__) && defined(XP_MACOSX)) || defined(__powerpc64__)
// ppc mac or powerpc64 linux
void* pc = *(aBp + 2);
aBp += 3;
#else // i386 or powerpc32 linux
void* pc = *(aBp + 1);
aBp += 2;
#endif
if (--skip < 0) {
// Assume that the SP points to the BP of the function
// it called. We can't know the exact location of the SP
// but this should be sufficient for our use the SP
// to order elements on the stack.
numFrames++;
(*aCallback)(numFrames, pc, aBp, aClosure);
if (aMaxFrames != 0 && numFrames == aMaxFrames) {
break;
}
}
aBp = next;
}
}
} // namespace mozilla
#else
namespace mozilla {
MFBT_API void
FramePointerStackWalk(MozWalkStackCallback aCallback, uint32_t aSkipFrames,
uint32_t aMaxFrames, void* aClosure, void** aBp,
void* aStackEnd)
{
}
}
#endif
MFBT_API void
MozFormatCodeAddressDetails(char* aBuffer, uint32_t aBufferSize,
uint32_t aFrameNumber, void* aPC,
const MozCodeAddressDetails* aDetails)
{
MozFormatCodeAddress(aBuffer, aBufferSize,
aFrameNumber, aPC, aDetails->function,
aDetails->library, aDetails->loffset,
aDetails->filename, aDetails->lineno);
}
MFBT_API void
MozFormatCodeAddress(char* aBuffer, uint32_t aBufferSize, uint32_t aFrameNumber,
const void* aPC, const char* aFunction,
const char* aLibrary, ptrdiff_t aLOffset,
const char* aFileName, uint32_t aLineNo)
{
const char* function = aFunction && aFunction[0] ? aFunction : "???";
if (aFileName && aFileName[0]) {
// We have a filename and (presumably) a line number. Use them.
snprintf(aBuffer, aBufferSize,
"#%02u: %s (%s:%u)",
aFrameNumber, function, aFileName, aLineNo);
} else if (aLibrary && aLibrary[0]) {
// We have no filename, but we do have a library name. Use it and the
// library offset, and print them in a way that scripts like
// fix_{linux,macosx}_stacks.py can easily post-process.
snprintf(aBuffer, aBufferSize,
"#%02u: %s[%s +0x%" PRIxPTR "]",
aFrameNumber, function, aLibrary, static_cast<uintptr_t>(aLOffset));
} else {
// We have nothing useful to go on. (The format string is split because
// '??)' is a trigraph and causes a warning, sigh.)
snprintf(aBuffer, aBufferSize,
"#%02u: ??? (???:???" ")",
aFrameNumber);
}
}
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