//===----------------------------------------------------------------------===//
#include "llvm/Support/CrashRecoveryContext.h"
-#include "llvm/ADT/SmallString.h"
#include "llvm/Config/config.h"
-#include "llvm/System/ThreadLocal.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/ManagedStatic.h"
+#include "llvm/Support/Mutex.h"
+#include "llvm/Support/ThreadLocal.h"
#include <setjmp.h>
-#include <cstdio>
using namespace llvm;
namespace {
struct CrashRecoveryContextImpl;
-static sys::ThreadLocal<const CrashRecoveryContextImpl> CurrentContext;
+static ManagedStatic<
+ sys::ThreadLocal<const CrashRecoveryContextImpl> > CurrentContext;
struct CrashRecoveryContextImpl {
+ // When threads are disabled, this links up all active
+ // CrashRecoveryContextImpls. When threads are enabled there's one thread
+ // per CrashRecoveryContext and CurrentContext is a thread-local, so only one
+ // CrashRecoveryContextImpl is active per thread and this is always null.
+ const CrashRecoveryContextImpl *Next;
+
+ CrashRecoveryContext *CRC;
std::string Backtrace;
::jmp_buf JumpBuffer;
volatile unsigned Failed : 1;
+ unsigned SwitchedThread : 1;
public:
- CrashRecoveryContextImpl() : Failed(false) {
- CurrentContext.set(this);
+ CrashRecoveryContextImpl(CrashRecoveryContext *CRC) : CRC(CRC),
+ Failed(false),
+ SwitchedThread(false) {
+ Next = CurrentContext->get();
+ CurrentContext->set(this);
}
~CrashRecoveryContextImpl() {
- CurrentContext.set(0);
+ if (!SwitchedThread)
+ CurrentContext->set(Next);
+ }
+
+ /// \brief Called when the separate crash-recovery thread was finished, to
+ /// indicate that we don't need to clear the thread-local CurrentContext.
+ void setSwitchedThread() {
+#if defined(LLVM_ENABLE_THREADS) && LLVM_ENABLE_THREADS != 0
+ SwitchedThread = true;
+#endif
}
void HandleCrash() {
+ // Eliminate the current context entry, to avoid re-entering in case the
+ // cleanup code crashes.
+ CurrentContext->set(Next);
+
assert(!Failed && "Crash recovery context already failed!");
Failed = true;
}
+static ManagedStatic<sys::Mutex> gCrashRecoveryContextMutex;
static bool gCrashRecoveryEnabled = false;
+static ManagedStatic<sys::ThreadLocal<const CrashRecoveryContext>>
+ tlIsRecoveringFromCrash;
+
+CrashRecoveryContextCleanup::~CrashRecoveryContextCleanup() {}
+
CrashRecoveryContext::~CrashRecoveryContext() {
+ // Reclaim registered resources.
+ CrashRecoveryContextCleanup *i = head;
+ const CrashRecoveryContext *PC = tlIsRecoveringFromCrash->get();
+ tlIsRecoveringFromCrash->set(this);
+ while (i) {
+ CrashRecoveryContextCleanup *tmp = i;
+ i = tmp->next;
+ tmp->cleanupFired = true;
+ tmp->recoverResources();
+ delete tmp;
+ }
+ tlIsRecoveringFromCrash->set(PC);
+
CrashRecoveryContextImpl *CRCI = (CrashRecoveryContextImpl *) Impl;
delete CRCI;
}
+bool CrashRecoveryContext::isRecoveringFromCrash() {
+ return tlIsRecoveringFromCrash->get() != nullptr;
+}
+
+CrashRecoveryContext *CrashRecoveryContext::GetCurrent() {
+ if (!gCrashRecoveryEnabled)
+ return nullptr;
+
+ const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
+ if (!CRCI)
+ return nullptr;
+
+ return CRCI->CRC;
+}
+
+void CrashRecoveryContext::registerCleanup(CrashRecoveryContextCleanup *cleanup)
+{
+ if (!cleanup)
+ return;
+ if (head)
+ head->prev = cleanup;
+ cleanup->next = head;
+ head = cleanup;
+}
+
+void
+CrashRecoveryContext::unregisterCleanup(CrashRecoveryContextCleanup *cleanup) {
+ if (!cleanup)
+ return;
+ if (cleanup == head) {
+ head = cleanup->next;
+ if (head)
+ head->prev = nullptr;
+ }
+ else {
+ cleanup->prev->next = cleanup->next;
+ if (cleanup->next)
+ cleanup->next->prev = cleanup->prev;
+ }
+ delete cleanup;
+}
+
#ifdef LLVM_ON_WIN32
-// FIXME: No real Win32 implementation currently.
+#include "Windows/WindowsSupport.h"
+
+// 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.
+//
+// Vectored exception handling is built on top of SEH, and so it
+// works on a per-thread basis.
+//
+// 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).
+
+static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo)
+{
+ // Lookup the current thread local recovery object.
+ const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
+
+ if (!CRCI) {
+ // Something has gone horribly wrong, so let's just tell everyone
+ // to keep searching
+ CrashRecoveryContext::Disable();
+ return EXCEPTION_CONTINUE_SEARCH;
+ }
+
+ // TODO: We can capture the stack backtrace here and store it on the
+ // implementation if we so choose.
+
+ // Handle the crash
+ const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
+
+ // Note that we don't actually get here because HandleCrash calls
+ // longjmp, which means the HandleCrash function never returns.
+ llvm_unreachable("Handled the crash, should have longjmp'ed out of here");
+}
+
+// Because the Enable and Disable calls are static, it means that
+// there may not actually be an Impl available, or even a current
+// CrashRecoveryContext at all. So we make use of a thread-local
+// exception table. The handles contained in here will either be
+// 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;
+
+ // 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
+ // our handler). This 1) isn't likely, and 2) shouldn't cause problems.
+ PVOID handle = ::AddVectoredExceptionHandler(1, ExceptionHandler);
+ sCurrentExceptionHandle.set(handle);
}
void CrashRecoveryContext::Disable() {
+ sys::ScopedLock L(*gCrashRecoveryContextMutex);
+
if (!gCrashRecoveryEnabled)
return;
gCrashRecoveryEnabled = false;
+
+ PVOID currentHandle = const_cast<PVOID>(sCurrentExceptionHandle.get());
+ if (currentHandle) {
+ // Now we can remove the vectored exception handler from the chain
+ ::RemoveVectoredExceptionHandler(currentHandle);
+
+ // Reset the handle in our thread-local set.
+ sCurrentExceptionHandle.set(NULL);
+ }
}
#else
#include <signal.h>
-static struct {
- int Signal;
- struct sigaction PrevAction;
-} SignalInfo[] = {
- { SIGABRT, {} },
- { SIGBUS, {} },
- { SIGFPE, {} },
- { SIGILL, {} },
- { SIGSEGV, {} },
- { SIGTRAP, {} },
-};
-static const unsigned NumSignals = sizeof(SignalInfo) / sizeof(SignalInfo[0]);
+static const int Signals[] =
+ { SIGABRT, SIGBUS, SIGFPE, SIGILL, SIGSEGV, SIGTRAP };
+static const unsigned NumSignals = array_lengthof(Signals);
+static struct sigaction PrevActions[NumSignals];
static void CrashRecoverySignalHandler(int Signal) {
// Lookup the current thread local recovery object.
- const CrashRecoveryContextImpl *CRCI = CurrentContext.get();
+ const CrashRecoveryContextImpl *CRCI = CurrentContext->get();
if (!CRCI) {
// We didn't find a crash recovery context -- this means either we got a
// This call of Disable isn't thread safe, but it doesn't actually matter.
CrashRecoveryContext::Disable();
raise(Signal);
+
+ // The signal will be thrown once the signal mask is restored.
+ return;
}
// Unblock the signal we received.
sigset_t SigMask;
sigemptyset(&SigMask);
sigaddset(&SigMask, Signal);
- sigprocmask(SIG_UNBLOCK, &SigMask, 0);
+ sigprocmask(SIG_UNBLOCK, &SigMask, nullptr);
if (CRCI)
const_cast<CrashRecoveryContextImpl*>(CRCI)->HandleCrash();
}
void CrashRecoveryContext::Enable() {
+ sys::ScopedLock L(*gCrashRecoveryContextMutex);
+
if (gCrashRecoveryEnabled)
return;
sigemptyset(&Handler.sa_mask);
for (unsigned i = 0; i != NumSignals; ++i) {
- sigaction(SignalInfo[i].Signal, &Handler,
- &SignalInfo[i].PrevAction);
+ sigaction(Signals[i], &Handler, &PrevActions[i]);
}
}
void CrashRecoveryContext::Disable() {
+ sys::ScopedLock L(*gCrashRecoveryContextMutex);
+
if (!gCrashRecoveryEnabled)
return;
// Restore the previous signal handlers.
for (unsigned i = 0; i != NumSignals; ++i)
- sigaction(SignalInfo[i].Signal, &SignalInfo[i].PrevAction, 0);
+ sigaction(Signals[i], &PrevActions[i], nullptr);
}
#endif
-bool CrashRecoveryContext::RunSafely(void (*Fn)(void*), void *UserData) {
+bool CrashRecoveryContext::RunSafely(function_ref<void()> Fn) {
// If crash recovery is disabled, do nothing.
if (gCrashRecoveryEnabled) {
assert(!Impl && "Crash recovery context already initialized!");
- CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl;
+ CrashRecoveryContextImpl *CRCI = new CrashRecoveryContextImpl(this);
Impl = CRCI;
if (setjmp(CRCI->JumpBuffer) != 0) {
}
}
- Fn(UserData);
+ Fn();
return true;
}
assert(CRC->Failed && "No crash was detected!");
return CRC->Backtrace;
}
+
+// FIXME: Portability.
+static void setThreadBackgroundPriority() {
+#ifdef __APPLE__
+ setpriority(PRIO_DARWIN_THREAD, 0, PRIO_DARWIN_BG);
+#endif
+}
+
+static bool hasThreadBackgroundPriority() {
+#ifdef __APPLE__
+ return getpriority(PRIO_DARWIN_THREAD, 0) == 1;
+#else
+ return false;
+#endif
+}
+
+namespace {
+struct RunSafelyOnThreadInfo {
+ function_ref<void()> Fn;
+ CrashRecoveryContext *CRC;
+ bool UseBackgroundPriority;
+ bool Result;
+};
+}
+
+static void RunSafelyOnThread_Dispatch(void *UserData) {
+ RunSafelyOnThreadInfo *Info =
+ reinterpret_cast<RunSafelyOnThreadInfo*>(UserData);
+
+ if (Info->UseBackgroundPriority)
+ setThreadBackgroundPriority();
+
+ Info->Result = Info->CRC->RunSafely(Info->Fn);
+}
+bool CrashRecoveryContext::RunSafelyOnThread(function_ref<void()> Fn,
+ unsigned RequestedStackSize) {
+ bool UseBackgroundPriority = hasThreadBackgroundPriority();
+ RunSafelyOnThreadInfo Info = { Fn, this, UseBackgroundPriority, false };
+ llvm_execute_on_thread(RunSafelyOnThread_Dispatch, &Info, RequestedStackSize);
+ if (CrashRecoveryContextImpl *CRC = (CrashRecoveryContextImpl *)Impl)
+ CRC->setSwitchedThread();
+ return Info.Result;
+}
projects / oota-llvm.git / blobdiff