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-rw-r--r--mozglue/misc/StackWalk.cpp1129
1 files changed, 1129 insertions, 0 deletions
diff --git a/mozglue/misc/StackWalk.cpp b/mozglue/misc/StackWalk.cpp
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+++ b/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/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/StackWalk.h"
+#ifdef XP_WIN
+# include "mozilla/StackWalkThread.h"
+# include <io.h>
+#else
+# include <unistd.h>
+#endif
+#include "mozilla/Sprintf.h"
+
+#include <string.h>
+
+#if defined(ANDROID) && defined(MOZ_LINKER)
+# include "Linker.h"
+# include <android/log.h>
+#endif
+
+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
+
+class FrameSkipper {
+ public:
+ constexpr FrameSkipper() : mSkipUntilAddr(0) {}
+ static uintptr_t AddressFromPC(const void* aPC) {
+#ifdef __arm__
+ // On 32-bit ARM, mask off the thumb bit to get the instruction address.
+ return uintptr_t(aPC) & ~1;
+#else
+ return uintptr_t(aPC);
+#endif
+ }
+ bool ShouldSkipPC(void* aPC) {
+ // Skip frames until we encounter the one we were initialized with,
+ // and then never skip again.
+ uintptr_t instructionAddress = AddressFromPC(aPC);
+ if (mSkipUntilAddr != 0) {
+ if (mSkipUntilAddr != instructionAddress) {
+ return true;
+ }
+ mSkipUntilAddr = 0;
+ }
+ return false;
+ }
+ explicit FrameSkipper(const void* aPC) : mSkipUntilAddr(AddressFromPC(aPC)) {}
+
+ private:
+ uintptr_t mSkipUntilAddr;
+};
+
+#ifdef XP_WIN
+
+# 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
+
+// DbgHelp functions are not thread-safe and should therefore be protected by
+// using this critical section. Only use the critical section after a
+// successful call to InitializeDbgHelp().
+CRITICAL_SECTION gDbgHelpCS;
+
+# if defined(_M_AMD64) || defined(_M_ARM64)
+// 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;
+
+void SuppressStackWalking() { ++sStackWalkSuppressions; }
+
+void DesuppressStackWalking() {
+ auto previousValue = sStackWalkSuppressions--;
+ // We should never desuppress from 0. See bug 1687510 comment 10 for an
+ // example in which this occured.
+ MOZ_RELEASE_ASSERT(previousValue);
+}
+
+MFBT_API
+AutoSuppressStackWalking::AutoSuppressStackWalking() { SuppressStackWalking(); }
+
+MFBT_API
+AutoSuppressStackWalking::~AutoSuppressStackWalking() {
+ DesuppressStackWalking();
+}
+
+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 || _M_ARM64
+
+// 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);
+}
+
+enum class DbgHelpInitFlags : bool {
+ BasicInit,
+ WithSymbolSupport,
+};
+
+// This function ensures that DbgHelp.dll is loaded in the current process,
+// and initializes the gDbgHelpCS critical section that we use to protect calls
+// to DbgHelp functions. If DbgHelpInitFlags::WithSymbolSupport is set, we
+// additionally call the symbol initialization functions from DbgHelp so that
+// symbol-related functions can be used.
+//
+// This function is thread-safe and reentrancy-safe. In debug and fuzzing
+// builds, MOZ_ASSERT and MOZ_CRASH walk the stack to print it before actually
+// crashing. Hence *any* MOZ_ASSERT or MOZ_CRASH failure reached from
+// InitializeDbgHelp() leads to rentrancy (see bug 1869997 for an example).
+// Such failures can occur indirectly when we load dbghelp.dll, because we
+// override various Microsoft-internal functions that are called upon DLL
+// loading.
+[[nodiscard]] static bool InitializeDbgHelp(
+ DbgHelpInitFlags aInitFlags = DbgHelpInitFlags::BasicInit) {
+ // In the code below, it is only safe to reach MOZ_ASSERT or MOZ_CRASH while
+ // sInitializationThreadId is set to the current thread id.
+ static Atomic<DWORD> sInitializationThreadId{0};
+ DWORD currentThreadId = ::GetCurrentThreadId();
+
+ // This code relies on Windows never giving us a current thread ID of zero.
+ // We make this assumption explicit, by failing if that should ever occur.
+ if (!currentThreadId) {
+ return false;
+ }
+
+ if (sInitializationThreadId == currentThreadId) {
+ // This is a reentrant call and we must abort here.
+ return false;
+ }
+
+ static const bool sHasInitializedDbgHelp = [currentThreadId]() {
+ sInitializationThreadId = currentThreadId;
+
+ ::InitializeCriticalSection(&gDbgHelpCS);
+ bool dbgHelpLoaded = static_cast<bool>(::LoadLibraryW(L"dbghelp.dll"));
+
+ MOZ_ASSERT(dbgHelpLoaded);
+ sInitializationThreadId = 0;
+ return dbgHelpLoaded;
+ }();
+
+ // If we don't need symbol initialization, we are done. If we need it, we
+ // can only proceed if DbgHelp initialization was successful.
+ if (aInitFlags == DbgHelpInitFlags::BasicInit || !sHasInitializedDbgHelp) {
+ return sHasInitializedDbgHelp;
+ }
+
+ static const bool sHasInitializedSymbols = [currentThreadId]() {
+ sInitializationThreadId = currentThreadId;
+
+ EnterCriticalSection(&gDbgHelpCS);
+ SymSetOptions(SYMOPT_LOAD_LINES | SYMOPT_UNDNAME);
+ bool symbolsInitialized = SymInitialize(GetCurrentProcess(), nullptr, TRUE);
+ /* XXX At some point we need to arrange to call SymCleanup */
+ LeaveCriticalSection(&gDbgHelpCS);
+
+ if (!symbolsInitialized) {
+ PrintError("SymInitialize");
+ }
+
+ MOZ_ASSERT(symbolsInitialized);
+ sInitializationThreadId = 0;
+ return symbolsInitialized;
+ }();
+
+ return sHasInitializedSymbols;
+}
+
+// Wrapper around a reference to a CONTEXT, to simplify access to main
+// platform-specific execution registers.
+// It also avoids using CONTEXT* nullable pointers.
+class CONTEXTGenericAccessors {
+ public:
+ explicit CONTEXTGenericAccessors(CONTEXT& aCONTEXT) : mCONTEXT(aCONTEXT) {}
+
+ CONTEXT* CONTEXTPtr() { return &mCONTEXT; }
+
+ inline auto& PC() {
+# if defined(_M_AMD64)
+ return mCONTEXT.Rip;
+# elif defined(_M_ARM64)
+ return mCONTEXT.Pc;
+# elif defined(_M_IX86)
+ return mCONTEXT.Eip;
+# else
+# error "unknown platform"
+# endif
+ }
+
+ inline auto& SP() {
+# if defined(_M_AMD64)
+ return mCONTEXT.Rsp;
+# elif defined(_M_ARM64)
+ return mCONTEXT.Sp;
+# elif defined(_M_IX86)
+ return mCONTEXT.Esp;
+# else
+# error "unknown platform"
+# endif
+ }
+
+ inline auto& BP() {
+# if defined(_M_AMD64)
+ return mCONTEXT.Rbp;
+# elif defined(_M_ARM64)
+ return mCONTEXT.Fp;
+# elif defined(_M_IX86)
+ return mCONTEXT.Ebp;
+# else
+# error "unknown platform"
+# endif
+ }
+
+ private:
+ CONTEXT& mCONTEXT;
+};
+
+/**
+ * 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.
+ */
+
+static void DoMozStackWalkThread(MozWalkStackCallback aCallback,
+ const void* aFirstFramePC, uint32_t aMaxFrames,
+ void* aClosure, HANDLE aThread,
+ CONTEXT* aContext) {
+# if defined(_M_IX86)
+ if (!InitializeDbgHelp()) {
+ return;
+ }
+# endif
+
+ HANDLE targetThread = aThread;
+ bool walkCallingThread;
+ if (!targetThread) {
+ targetThread = ::GetCurrentThread();
+ walkCallingThread = true;
+ } else {
+ DWORD targetThreadId = ::GetThreadId(targetThread);
+ DWORD currentThreadId = ::GetCurrentThreadId();
+ walkCallingThread = (targetThreadId == currentThreadId);
+ }
+
+ // If not already provided, get a context for the specified thread.
+ CONTEXT context_buf;
+ if (!aContext) {
+ memset(&context_buf, 0, sizeof(CONTEXT));
+ context_buf.ContextFlags = CONTEXT_FULL;
+ if (walkCallingThread) {
+ ::RtlCaptureContext(&context_buf);
+ } else if (!GetThreadContext(targetThread, &context_buf)) {
+ return;
+ }
+ }
+ CONTEXTGenericAccessors context{aContext ? *aContext : context_buf};
+
+# if defined(_M_IX86)
+ // Setup initial stack frame to walk from.
+ STACKFRAME64 frame64;
+ memset(&frame64, 0, sizeof(frame64));
+ frame64.AddrPC.Offset = context.PC();
+ frame64.AddrStack.Offset = context.SP();
+ frame64.AddrFrame.Offset = context.BP();
+ frame64.AddrPC.Mode = AddrModeFlat;
+ frame64.AddrStack.Mode = AddrModeFlat;
+ frame64.AddrFrame.Mode = AddrModeFlat;
+ frame64.AddrReturn.Mode = AddrModeFlat;
+# endif
+
+# if defined(_M_AMD64) || defined(_M_ARM64)
+ // 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;
+ }
+
+ bool firstFrame = true;
+# endif
+
+ FrameSkipper skipper(aFirstFramePC);
+
+ uint32_t frames = 0;
+
+ // Now walk the stack.
+ while (true) {
+ DWORD64 addr;
+ DWORD64 spaddr;
+
+# if defined(_M_IX86)
+ // 32-bit frame unwinding.
+ // Debug routines are not threadsafe, so grab the lock.
+ EnterCriticalSection(&gDbgHelpCS);
+ BOOL ok =
+ StackWalk64(IMAGE_FILE_MACHINE_I386, ::GetCurrentProcess(),
+ targetThread, &frame64, context.CONTEXTPtr(), 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 (walkCallingThread) {
+ PrintError("WalkStack64");
+ }
+ }
+
+ if (!ok) {
+ break;
+ }
+
+# elif defined(_M_AMD64) || defined(_M_ARM64)
+
+ auto currentInstr = context.PC();
+
+ // 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*)currentInstr >= sJitCodeRegionStart &&
+ (uint8_t*)currentInstr < 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*)currentInstr >= sMsMpegJitCodeRegionStart &&
+ (uint8_t*)currentInstr <
+ sMsMpegJitCodeRegionStart + sMsMpegJitCodeRegionSize) {
+ break;
+ }
+
+ // 64-bit frame unwinding.
+ // Try to look up unwind metadata for the current function.
+ ULONG64 imageBase;
+ PRUNTIME_FUNCTION runtimeFunction =
+ RtlLookupFunctionEntry(currentInstr, &imageBase, NULL);
+
+ if (runtimeFunction) {
+ PVOID dummyHandlerData;
+ ULONG64 dummyEstablisherFrame;
+ RtlVirtualUnwind(UNW_FLAG_NHANDLER, imageBase, currentInstr,
+ runtimeFunction, context.CONTEXTPtr(), &dummyHandlerData,
+ &dummyEstablisherFrame, nullptr);
+ } else if (firstFrame) {
+ // Leaf functions can be unwound by hand.
+ context.PC() = *reinterpret_cast<DWORD64*>(context.SP());
+ context.SP() += sizeof(void*);
+ } else {
+ // Something went wrong.
+ break;
+ }
+
+ addr = context.PC();
+ spaddr = context.SP();
+ firstFrame = false;
+# else
+# error "unknown platform"
+# endif
+
+ if (addr == 0) {
+ break;
+ }
+
+ if (skipper.ShouldSkipPC((void*)addr)) {
+ continue;
+ }
+
+ aCallback(++frames, (void*)addr, (void*)spaddr, aClosure);
+
+ if (aMaxFrames != 0 && frames == aMaxFrames) {
+ break;
+ }
+
+# if defined(_M_IX86)
+ if (frame64.AddrReturn.Offset == 0) {
+ break;
+ }
+# endif
+ }
+}
+
+MFBT_API void MozStackWalkThread(MozWalkStackCallback aCallback,
+ uint32_t aMaxFrames, void* aClosure,
+ HANDLE aThread, CONTEXT* aContext) {
+ // We don't pass a aFirstFramePC because we walk the stack for another
+ // thread.
+ DoMozStackWalkThread(aCallback, nullptr, aMaxFrames, aClosure, aThread,
+ aContext);
+}
+
+MFBT_API void MozStackWalk(MozWalkStackCallback aCallback,
+ const void* aFirstFramePC, uint32_t aMaxFrames,
+ void* aClosure) {
+ DoMozStackWalkThread(aCallback, aFirstFramePC ? aFirstFramePC : CallerPC(),
+ 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;
+}
+
+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 (!InitializeDbgHelp(DbgHelpInitFlags::WithSymbolSupport)) {
+ 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
+//
+// Changes to to OS/Architecture support here should be reflected in
+// build/moz.configure/memory.configure
+#elif HAVE_DLADDR && \
+ (HAVE__UNWIND_BACKTRACE || MOZ_STACKWALK_SUPPORTS_LINUX || \
+ MOZ_STACKWALK_SUPPORTS_MACOSX)
+
+# include <stdlib.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
+
+namespace mozilla {
+
+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
+}
+
+} // namespace mozilla
+
+// {x86, ppc} x {Linux, Mac} stackwalking code.
+//
+// Changes to to OS/Architecture support here should be reflected in
+// build/moz.configure/memory.configure
+# if ((defined(__i386) || defined(PPC) || defined(__ppc__)) && \
+ (MOZ_STACKWALK_SUPPORTS_MACOSX || MOZ_STACKWALK_SUPPORTS_LINUX))
+
+static void DoFramePointerStackWalk(MozWalkStackCallback aCallback,
+ const void* aFirstFramePC,
+ uint32_t aMaxFrames, void* aClosure,
+ void** aBp, void* aStackEnd);
+
+MFBT_API void MozStackWalk(MozWalkStackCallback aCallback,
+ const void* aFirstFramePC, 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
+ DoFramePointerStackWalk(aCallback, aFirstFramePC, 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;
+ FrameSkipper skipper;
+ 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->skipper.ShouldSkipPC(pc)) {
+ 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,
+ const void* aFirstFramePC, uint32_t aMaxFrames,
+ void* aClosure) {
+ unwind_info info;
+ info.callback = aCallback;
+ info.skipper = FrameSkipper(aFirstFramePC ? aFirstFramePC : CallerPC());
+ 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;
+
+# if defined(ANDROID) && defined(MOZ_LINKER)
+ int ok = __wrap_dladdr(aPC, &info);
+# else
+ int ok = dladdr(aPC, &info);
+# endif
+
+ 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;
+
+# if !defined(XP_FREEBSD)
+ // On FreeBSD, dli_sname is unusably bad, it often returns things like
+ // 'gtk_xtbin_new' or 'XRE_GetBootstrap' instead of long C++ symbols. Just let
+ // GetFunction do the lookup directly in the ELF image.
+
+ 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;
+# endif
+
+ return true;
+}
+
+#else // unsupported platform.
+
+MFBT_API void MozStackWalk(MozWalkStackCallback aCallback,
+ const void* aFirstFramePC, 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)
+
+# if defined(XP_MACOSX) && defined(__aarch64__)
+// On macOS arm64, system libraries are arm64e binaries, and arm64e can do
+// pointer authentication: The low bits of the pointer are the actual pointer
+// value, and the high bits are an encrypted hash. During stackwalking, we need
+// to strip off this hash. In theory, ptrauth_strip would be the right function
+// to call for this. However, that function is a no-op unless it's called from
+// code which also builds as arm64e - which we do not. So we cannot use it. So
+// for now, we hardcode a mask that seems to work today: 40 bits for the pointer
+// and 24 bits for the hash seems to do the trick. We can worry about
+// dynamically computing the correct mask if this ever stops working.
+const uintptr_t kPointerMask =
+ (uintptr_t(1) << 40) - 1; // 40 bits pointer, 24 bit PAC
+# else
+const uintptr_t kPointerMask = ~uintptr_t(0);
+# endif
+
+MOZ_ASAN_IGNORE
+static void DoFramePointerStackWalk(MozWalkStackCallback aCallback,
+ const void* aFirstFramePC,
+ uint32_t aMaxFrames, void* aClosure,
+ void** aBp, void* aStackEnd) {
+ // Stack walking code courtesy Kipp's "leaky".
+
+ FrameSkipper skipper(aFirstFramePC);
+ uint32_t numFrames = 0;
+
+ // Sanitize the given aBp. Assume that something reasonably close to
+ // but before the stack end is going be a valid frame pointer. Also
+ // check that it is an aligned address. This increases the chances
+ // that if the pointer is not valid (which might happen if the caller
+ // called __builtin_frame_address(1) and its frame is busted for some
+ // reason), we won't read it, leading to a crash. Because the calling
+ // code is not using frame pointers when returning, it might actually
+ // recover just fine.
+ static const uintptr_t kMaxStackSize = 8 * 1024 * 1024;
+ if (uintptr_t(aBp) < uintptr_t(aStackEnd) -
+ std::min(kMaxStackSize, uintptr_t(aStackEnd)) ||
+ aBp >= aStackEnd || (uintptr_t(aBp) & 3)) {
+ return;
+ }
+
+ 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
+
+ // Strip off pointer authentication hash, if present. For now, it looks
+ // like only return addresses require stripping, and stack pointers do
+ // not. This might change in the future.
+ pc = (void*)((uintptr_t)pc & kPointerMask);
+
+ if (!skipper.ShouldSkipPC(pc)) {
+ // 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 {
+
+MFBT_API void FramePointerStackWalk(MozWalkStackCallback aCallback,
+ uint32_t aMaxFrames, void* aClosure,
+ void** aBp, void* aStackEnd) {
+ // We don't pass a aFirstFramePC because we start walking the stack from the
+ // frame at aBp.
+ DoFramePointerStackWalk(aCallback, nullptr, aMaxFrames, aClosure, aBp,
+ aStackEnd);
+}
+
+} // namespace mozilla
+
+#else
+
+namespace mozilla {
+MFBT_API void FramePointerStackWalk(MozWalkStackCallback aCallback,
+ uint32_t aMaxFrames, void* aClosure,
+ void** aBp, void* aStackEnd) {}
+} // namespace mozilla
+
+#endif
+
+MFBT_API int MozFormatCodeAddressDetails(
+ char* aBuffer, uint32_t aBufferSize, uint32_t aFrameNumber, void* aPC,
+ const MozCodeAddressDetails* aDetails) {
+ return MozFormatCodeAddress(aBuffer, aBufferSize, aFrameNumber, aPC,
+ aDetails->function, aDetails->library,
+ aDetails->loffset, aDetails->filename,
+ aDetails->lineno);
+}
+
+MFBT_API int 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.
+ return SprintfBuf(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 `fix_stacks.py` can
+ // post-process.
+ return SprintfBuf(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.)
+ return SprintfBuf(aBuffer, aBufferSize,
+ "#%02u: ??? (???:???"
+ ")",
+ aFrameNumber);
+ }
+}
+
+static void EnsureWrite(FILE* aStream, const char* aBuf, size_t aLen) {
+#ifdef XP_WIN
+ int fd = _fileno(aStream);
+#else
+ int fd = fileno(aStream);
+#endif
+ while (aLen > 0) {
+#ifdef XP_WIN
+ auto written = _write(fd, aBuf, aLen);
+#else
+ auto written = write(fd, aBuf, aLen);
+#endif
+ if (written <= 0 || size_t(written) > aLen) {
+ break;
+ }
+ aBuf += written;
+ aLen -= written;
+ }
+}
+
+template <int N>
+static int PrintStackFrameBuf(char (&aBuf)[N], uint32_t aFrameNumber, void* aPC,
+ void* aSP) {
+ MozCodeAddressDetails details;
+ MozDescribeCodeAddress(aPC, &details);
+ int len =
+ MozFormatCodeAddressDetails(aBuf, N - 1, aFrameNumber, aPC, &details);
+ len = std::min(len, N - 2);
+ aBuf[len++] = '\n';
+ aBuf[len] = '\0';
+ return len;
+}
+
+static void PrintStackFrame(uint32_t aFrameNumber, void* aPC, void* aSP,
+ void* aClosure) {
+ FILE* stream = (FILE*)aClosure;
+ char buf[1025]; // 1024 + 1 for trailing '\n'
+ int len = PrintStackFrameBuf(buf, aFrameNumber, aPC, aSP);
+ fflush(stream);
+ EnsureWrite(stream, buf, len);
+}
+
+static bool WalkTheStackEnabled() {
+ static bool result = [] {
+ char* value = getenv("MOZ_DISABLE_WALKTHESTACK");
+ return !(value && value[0]);
+ }();
+ return result;
+}
+
+MFBT_API void MozWalkTheStack(FILE* aStream, const void* aFirstFramePC,
+ uint32_t aMaxFrames) {
+ if (WalkTheStackEnabled()) {
+ MozStackWalk(PrintStackFrame, aFirstFramePC ? aFirstFramePC : CallerPC(),
+ aMaxFrames, aStream);
+ }
+}
+
+static void WriteStackFrame(uint32_t aFrameNumber, void* aPC, void* aSP,
+ void* aClosure) {
+ auto writer = (void (*)(const char*))aClosure;
+ char buf[1024];
+ PrintStackFrameBuf(buf, aFrameNumber, aPC, aSP);
+ writer(buf);
+}
+
+MFBT_API void MozWalkTheStackWithWriter(void (*aWriter)(const char*),
+ const void* aFirstFramePC,
+ uint32_t aMaxFrames) {
+ if (WalkTheStackEnabled()) {
+ MozStackWalk(WriteStackFrame, aFirstFramePC ? aFirstFramePC : CallerPC(),
+ aMaxFrames, (void*)aWriter);
+ }
+}