diff options
Diffstat (limited to 'lib/Support/CrashRecoveryContext.cpp')
| -rw-r--r-- | lib/Support/CrashRecoveryContext.cpp | 130 |
1 files changed, 82 insertions, 48 deletions
diff --git a/lib/Support/CrashRecoveryContext.cpp b/lib/Support/CrashRecoveryContext.cpp index 98865f5e065e..bd38dd88201f 100644 --- a/lib/Support/CrashRecoveryContext.cpp +++ b/lib/Support/CrashRecoveryContext.cpp @@ -78,6 +78,9 @@ static bool gCrashRecoveryEnabled = false; static ManagedStatic<sys::ThreadLocal<const CrashRecoveryContext>> tlIsRecoveringFromCrash; +static void installExceptionOrSignalHandlers(); +static void uninstallExceptionOrSignalHandlers(); + CrashRecoveryContextCleanup::~CrashRecoveryContextCleanup() {} CrashRecoveryContext::~CrashRecoveryContext() { @@ -113,6 +116,23 @@ CrashRecoveryContext *CrashRecoveryContext::GetCurrent() { return CRCI->CRC; } +void CrashRecoveryContext::Enable() { + sys::ScopedLock L(*gCrashRecoveryContextMutex); + // FIXME: Shouldn't this be a refcount or something? + if (gCrashRecoveryEnabled) + return; + gCrashRecoveryEnabled = true; + installExceptionOrSignalHandlers(); +} + +void CrashRecoveryContext::Disable() { + sys::ScopedLock L(*gCrashRecoveryContextMutex); + if (!gCrashRecoveryEnabled) + return; + gCrashRecoveryEnabled = false; + uninstallExceptionOrSignalHandlers(); +} + void CrashRecoveryContext::registerCleanup(CrashRecoveryContextCleanup *cleanup) { if (!cleanup) @@ -140,30 +160,70 @@ CrashRecoveryContext::unregisterCleanup(CrashRecoveryContextCleanup *cleanup) { delete cleanup; } -#ifdef LLVM_ON_WIN32 +#if defined(_MSC_VER) +// If _MSC_VER is defined, we must have SEH. Use it if it's available. It's way +// better than VEH. Vectored exception handling catches all exceptions happening +// on the thread with installed exception handlers, so it can interfere with +// internal exception handling of other libraries on that thread. SEH works +// exactly as you would expect normal exception handling to work: it only +// catches exceptions if they would bubble out from the stack frame with __try / +// __except. -#include "Windows/WindowsSupport.h" +static void installExceptionOrSignalHandlers() {} +static void uninstallExceptionOrSignalHandlers() {} -// On Windows, we can make use of vectored exception handling to -// catch most crashing situations. Note that this does mean -// we will be alerted of exceptions *before* structured exception -// handling has the opportunity to catch it. But that isn't likely -// to cause problems because nowhere in the project is SEH being -// used. +bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) { + if (!gCrashRecoveryEnabled) { + Fn(); + return true; + } + + bool Result = true; + __try { + Fn(); + } __except (1) { // Catch any exception. + Result = false; + } + return Result; +} + +#else // !_MSC_VER + +#if defined(LLVM_ON_WIN32) +// This is a non-MSVC compiler, probably mingw gcc or clang without +// -fms-extensions. Use vectored exception handling (VEH). +// +// On Windows, we can make use of vectored exception handling to catch most +// crashing situations. Note that this does mean we will be alerted of +// exceptions *before* structured exception handling has the opportunity to +// catch it. Unfortunately, this causes problems in practice with other code +// running on threads with LLVM crash recovery contexts, so we would like to +// eventually move away from VEH. // -// Vectored exception handling is built on top of SEH, and so it -// works on a per-thread basis. +// Vectored works on a per-thread basis, which is an advantage over +// SetUnhandledExceptionFilter. SetUnhandledExceptionFilter also doesn't have +// any native support for chaining exception handlers, but VEH allows more than +// one. // // The vectored exception handler functionality was added in Windows // XP, so if support for older versions of Windows is required, // it will have to be added. -// -// If we want to support as far back as Win2k, we could use the -// SetUnhandledExceptionFilter API, but there's a risk of that -// being entirely overwritten (it's not a chain). + +#include "Windows/WindowsSupport.h" static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo) { + // DBG_PRINTEXCEPTION_WIDE_C is not properly defined on all supported + // compilers and platforms, so we define it manually. + constexpr ULONG DbgPrintExceptionWideC = 0x4001000AL; + switch (ExceptionInfo->ExceptionRecord->ExceptionCode) + { + case DBG_PRINTEXCEPTION_C: + case DbgPrintExceptionWideC: + case 0x406D1388: // set debugger thread name + return EXCEPTION_CONTINUE_EXECUTION; + } + // Lookup the current thread local recovery object. const CrashRecoveryContextImpl *CRCI = CurrentContext->get(); @@ -192,14 +252,7 @@ static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo) // non-NULL, valid VEH handles, or NULL. static sys::ThreadLocal<const void> sCurrentExceptionHandle; -void CrashRecoveryContext::Enable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = true; - +static void installExceptionOrSignalHandlers() { // We can set up vectored exception handling now. We will install our // handler as the front of the list, though there's no assurances that // it will remain at the front (another call could install itself before @@ -208,14 +261,7 @@ void CrashRecoveryContext::Enable() { sCurrentExceptionHandle.set(handle); } -void CrashRecoveryContext::Disable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (!gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = false; - +static void uninstallExceptionOrSignalHandlers() { PVOID currentHandle = const_cast<PVOID>(sCurrentExceptionHandle.get()); if (currentHandle) { // Now we can remove the vectored exception handler from the chain @@ -226,7 +272,7 @@ void CrashRecoveryContext::Disable() { } } -#else +#else // !LLVM_ON_WIN32 // Generic POSIX implementation. // @@ -278,14 +324,7 @@ static void CrashRecoverySignalHandler(int Signal) { const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash(); } -void CrashRecoveryContext::Enable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = true; - +static void installExceptionOrSignalHandlers() { // Setup the signal handler. struct sigaction Handler; Handler.sa_handler = CrashRecoverySignalHandler; @@ -297,20 +336,13 @@ void CrashRecoveryContext::Enable() { } } -void CrashRecoveryContext::Disable() { - sys::ScopedLock L(*gCrashRecoveryContextMutex); - - if (!gCrashRecoveryEnabled) - return; - - gCrashRecoveryEnabled = false; - +static void uninstallExceptionOrSignalHandlers() { // Restore the previous signal handlers. for (unsigned i = 0; i != NumSignals; ++i) sigaction(Signals[i], &PrevActions[i], nullptr); } -#endif +#endif // !LLVM_ON_WIN32 bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) { // If crash recovery is disabled, do nothing. @@ -328,6 +360,8 @@ bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) { return true; } +#endif // !_MSC_VER + void CrashRecoveryContext::HandleCrash() { CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl; assert(CRCI && "Crash recovery context never initialized!"); |