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threadsuspend.cpp
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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
//
// threadsuspend.CPP
//
// This file contains the implementation of thread suspension. The implementation of thread suspension
// used to be spread through multiple places. That is why, many methods still live in their own homes
// (class Thread, class ThreadStore, etc.). They should be eventually refactored into class ThreadSuspend.
//
#include "common.h"
#include "threadsuspend.h"
#include "finalizerthread.h"
#include "dbginterface.h"
// from ntstatus.h
#define STATUS_SUSPEND_COUNT_EXCEEDED ((NTSTATUS)0xC000004AL)
#define HIJACK_NONINTERRUPTIBLE_THREADS
bool ThreadSuspend::s_fSuspendRuntimeInProgress = false;
bool ThreadSuspend::s_fSuspended = false;
CLREvent* ThreadSuspend::g_pGCSuspendEvent = NULL;
ThreadSuspend::SUSPEND_REASON ThreadSuspend::m_suspendReason;
#if defined(TARGET_WINDOWS) && defined(TARGET_AMD64)
void* ThreadSuspend::g_returnAddressHijackTarget = NULL;
#endif
// If you add any thread redirection function, make sure the debugger can 1) recognize the redirection
// function, and 2) retrieve the original CONTEXT. See code:Debugger.InitializeHijackFunctionAddress and
// code:DacDbiInterfaceImpl.RetrieveHijackedContext.
extern "C" void RedirectedHandledJITCaseForGCThreadControl_Stub(void);
extern "C" void RedirectedHandledJITCaseForDbgThreadControl_Stub(void);
extern "C" void RedirectedHandledJITCaseForUserSuspend_Stub(void);
#ifdef FEATURE_SPECIAL_USER_MODE_APC
extern "C" void NTAPI ApcActivationCallbackStub(ULONG_PTR Parameter);
#endif
#define GetRedirectHandlerForGCThreadControl() \
((PFN_REDIRECTTARGET) GetEEFuncEntryPoint(RedirectedHandledJITCaseForGCThreadControl_Stub))
#define GetRedirectHandlerForDbgThreadControl() \
((PFN_REDIRECTTARGET) GetEEFuncEntryPoint(RedirectedHandledJITCaseForDbgThreadControl_Stub))
#define GetRedirectHandlerForUserSuspend() \
((PFN_REDIRECTTARGET) GetEEFuncEntryPoint(RedirectedHandledJITCaseForUserSuspend_Stub))
#ifdef FEATURE_SPECIAL_USER_MODE_APC
#define GetRedirectHandlerForApcActivation() \
((PAPCFUNC) GetEEFuncEntryPoint(ApcActivationCallbackStub))
#endif
#if defined(TARGET_AMD64) || defined(TARGET_ARM) || defined(TARGET_ARM64)
#if defined(HAVE_GCCOVER) && defined(USE_REDIRECT_FOR_GCSTRESS) // GCCOVER
extern "C" void RedirectedHandledJITCaseForGCStress_Stub(void);
#define GetRedirectHandlerForGCStress() \
((PFN_REDIRECTTARGET) GetEEFuncEntryPoint(RedirectedHandledJITCaseForGCStress_Stub))
#endif // HAVE_GCCOVER && USE_REDIRECT_FOR_GCSTRESS
#endif // TARGET_AMD64 || TARGET_ARM
// Every PING_JIT_TIMEOUT ms, check to see if a thread in JITted code has wandered
// into some fully interruptible code (or should have a different hijack to improve
// our chances of snagging it at a safe spot).
#define PING_JIT_TIMEOUT 1
// When we find a thread in a spot that's not safe to abort -- how long to wait before
// we try again.
#define ABORT_POLL_TIMEOUT 10
#ifdef _DEBUG
#define ABORT_FAIL_TIMEOUT 40000
#endif // _DEBUG
//
// CANNOT USE IsBad*Ptr() methods here. They are *banned* APIs because of various
// reasons (see http://winweb/wincet/bannedapis.htm).
//
#define IS_VALID_WRITE_PTR(addr, size) _ASSERTE((addr) != NULL)
#define IS_VALID_CODE_PTR(addr) _ASSERTE((addr) != NULL)
void ThreadSuspend::SetSuspendRuntimeInProgress()
{
LIMITED_METHOD_CONTRACT;
_ASSERTE(ThreadStore::HoldingThreadStore() || IsAtProcessExit());
_ASSERTE(!s_fSuspendRuntimeInProgress || IsAtProcessExit());
s_fSuspendRuntimeInProgress = true;
}
void ThreadSuspend::ResetSuspendRuntimeInProgress()
{
LIMITED_METHOD_CONTRACT;
_ASSERTE(ThreadStore::HoldingThreadStore() || IsAtProcessExit());
_ASSERTE(s_fSuspendRuntimeInProgress || IsAtProcessExit());
s_fSuspendRuntimeInProgress = false;
}
// When SuspendThread returns, target thread may still be executing user code.
// We can not access data, e.g. m_fPreemptiveGCDisabled, changed by target thread.
// But our code depends on reading these data. To make this operation safe, we
// call GetThreadContext which returns only after target thread does not execute
// any user code.
// Message from David Cutler
/*
After SuspendThread returns, can the suspended thread continue to execute code in user mode?
[David Cutler] The suspended thread cannot execute any more user code, but it might be currently "running"
on a logical processor whose other logical processor is currently actually executing another thread.
In this case the target thread will not suspend until the hardware switches back to executing instructions
on its logical processor. In this case even the memory barrier would not necessarily work - a better solution
would be to use interlocked operations on the variable itself.
After SuspendThread returns, does the store buffer of the CPU for the suspended thread still need to drain?
Historically, we've assumed that the answer to both questions is No. But on one 4/8 hyper-threaded machine
running Win2K3 SP1 build 1421, we've seen two stress failures where SuspendThread returns while writes seem to still be in flight.
Usually after we suspend a thread, we then call GetThreadContext. This seems to guarantee consistency.
But there are places we would like to avoid GetThreadContext, if it's safe and legal.
[David Cutler] Get context delivers a APC to the target thread and waits on an event that will be set
when the target thread has delivered its context.
Chris.
*/
// Message from Neill Clift
/*
What SuspendThread does is insert an APC block into a target thread and request an inter-processor interrupt to
do the APC interrupt. It doesn't wait till the thread actually enters some state or the interrupt has been serviced.
I took a quick look at the APIC spec in the Intel manuals this morning. Writing to the APIC posts a message on a bus.
Processors accept messages and presumably queue the s/w interrupts at this time. We don't wait for this acceptance
when we send the IPI so at least on APIC machines when you suspend a thread it continues to execute code for some short time
after the routine returns. We use other mechanisms for IPI and so it could work differently on different h/w.
*/
BOOL EnsureThreadIsSuspended (HANDLE hThread, Thread* pThread)
{
STATIC_CONTRACT_NOTHROW;
STATIC_CONTRACT_GC_NOTRIGGER;
WRAPPER_NO_CONTRACT;
CONTEXT ctx;
ctx.ContextFlags = CONTEXT_INTEGER;
BOOL ret;
ret = ::GetThreadContext(hThread, &ctx);
return ret;
}
FORCEINLINE VOID MyEnterLogLock()
{
EnterLogLock();
}
FORCEINLINE VOID MyLeaveLogLock()
{
LeaveLogLock();
}
// On non-Windows CORECLR platforms remove Thread::SuspendThread support
#ifndef DISABLE_THREADSUSPEND
// SuspendThread
// Attempts to OS-suspend the thread, whichever GC mode it is in.
// Arguments:
// fOneTryOnly - If TRUE, report failure if the thread has its
// m_dwForbidSuspendThread flag set. If FALSE, retry.
// pdwSuspendCount - If non-NULL, will contain the return code
// of the underlying OS SuspendThread call on success,
// undefined on any kind of failure.
// Return value:
// A SuspendThreadResult value indicating success or failure.
Thread::SuspendThreadResult Thread::SuspendThread(BOOL fOneTryOnly, DWORD *pdwSuspendCount)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
#ifdef STRESS_LOG
if (StressLog::StressLogOn((unsigned int)-1, 0))
{
// Make sure to create the stress log for the current thread
// (if needed) before we suspend the target thread. The target
// thread may be holding the stress log lock when we suspend it,
// which could cause a deadlock.
if (StressLog::CreateThreadStressLog() == NULL)
{
return STR_NoStressLog;
}
}
#endif
HANDLE hThread;
SuspendThreadResult str = (SuspendThreadResult) -1;
DWORD dwSuspendCount = 0;
DWORD tries = 1;
#if defined(_DEBUG)
int nCnt = 0;
bool bDiagSuspend = g_pConfig->GetDiagnosticSuspend();
ULONGLONG i64TimestampStart = CLRGetTickCount64();
ULONGLONG i64TimestampCur = i64TimestampStart;
ULONGLONG i64TimestampPrev = i64TimestampStart;
// This is the max allowed timestamp ticks to transpire from beginning of
// our attempt to suspend the thread, before we'll assert (implying we believe
// there might be a deadlock) - (default = 2000).
ULONGLONG i64TimestampTicksMax = g_pConfig->SuspendThreadDeadlockTimeoutMs();
#endif // _DEBUG
#if defined(_DEBUG)
// Stop the stress log from allocating any new memory while in this function
// as that can lead to deadlocks
CantAllocHolder hldrCantAlloc;
#endif
DWORD dwSwitchCount = 0;
while (TRUE) {
StateHolder<MyEnterLogLock, MyLeaveLogLock> LogLockHolder(FALSE);
CounterHolder handleHolder(&m_dwThreadHandleBeingUsed);
hThread = GetThreadHandle();
if (hThread == INVALID_HANDLE_VALUE) {
str = STR_UnstartedOrDead;
break;
}
{
// We do not want to suspend the target thread while it is holding the log lock.
// By acquiring the lock ourselves, we know that this is not the case.
// Note: LogLock is a noop when not logging, do not assume the rest is running under a lock.
LogLockHolder.Acquire();
// It is important to avoid two threads suspending each other.
// Before a thread suspends another, it increments its own m_dwForbidSuspendThread count first,
// then it checks the target thread's m_dwForbidSuspendThread.
ForbidSuspendThreadHolder forbidSuspend;
// We need a total order between write/read of our/their m_dwForbidSuspendThread here, thus a full fence.
// Note - this is just to prevent mutual suspension of two threads executing this same sequence.
// The other thread may still set its m_dwForbidSuspendThread for other reasons asynchronously.
// We will check on that once the thread is suspended.
if (InterlockedOr(&m_dwForbidSuspendThread, 0))
{
#if defined(_DEBUG)
// Enable the diagnostic ClrSuspendThread() if the
// DiagnosticSuspend config setting is set.
// This will interfere with the mutual suspend race but it's
// here only for diagnostic purposes anyway
if (!bDiagSuspend)
#endif // _DEBUG
goto retry;
}
dwSuspendCount = ClrSuspendThread(hThread);
//
// Since SuspendThread is asynchronous, we now must wait for the thread to
// actually be suspended before decrementing our own m_dwForbidSuspendThread count.
// Otherwise there would still be a chance for the "suspended" thread to suspend us
// before it really stops running.
//
if ((int)dwSuspendCount >= 0)
{
if (!EnsureThreadIsSuspended(hThread, this))
{
ClrResumeThread(hThread);
str = STR_Failure;
break;
}
}
}
if ((int)dwSuspendCount >= 0)
{
// read m_dwForbidSuspendThread again after suspension, it may have changed.
if (m_dwForbidSuspendThread.LoadWithoutBarrier() != 0)
{
#if defined(_DEBUG)
// Log diagnostic below 8 times during the i64TimestampTicksMax period
if (i64TimestampCur-i64TimestampStart >= nCnt*(i64TimestampTicksMax>>3) )
{
CONTEXT ctx;
SetIP(&ctx, -1);
ctx.ContextFlags = CONTEXT_CONTROL;
this->GetThreadContext(&ctx);
STRESS_LOG7(LF_SYNC, LL_INFO1000,
"Thread::SuspendThread[%p]: EIP=%p. nCnt=%d. result=%d.\n"
"\t\t\t\t\t\t\t\t\t forbidSuspend=%d. coop=%d. state=%x.\n",
this, GetIP(&ctx), nCnt, dwSuspendCount,
(LONG)this->m_dwForbidSuspendThread, (ULONG)this->m_fPreemptiveGCDisabled, this->GetSnapshotState());
// Enable a preemptive assert in diagnostic mode: before we
// resume the target thread to get its current state in the debugger
if (bDiagSuspend)
{
// triggered after 6 * 250msec
_ASSERTE(nCnt < 6 && "Timing out in Thread::SuspendThread");
}
++nCnt;
}
#endif // _DEBUG
ClrResumeThread(hThread);
#if defined(_DEBUG)
// If the suspend diagnostics are enabled we need to spin here in order to avoid
// the case where we Suspend/Resume the target thread without giving it a chance to run.
if ((!fOneTryOnly) && bDiagSuspend)
{
while ( m_dwForbidSuspendThread != 0 &&
CLRGetTickCount64()-i64TimestampStart < nCnt*(i64TimestampTicksMax>>3) )
{
if (g_SystemInfo.dwNumberOfProcessors > 1)
{
if ((tries++) % 20 != 0) {
YieldProcessorNormalized(); // play nice on hyperthreaded CPUs
} else {
__SwitchToThread(0, ++dwSwitchCount);
}
}
else
{
__SwitchToThread(0, ++dwSwitchCount); // don't spin on uniproc machines
}
}
}
#endif // _DEBUG
goto retry;
}
// We suspend the right thread
#ifdef _DEBUG
Thread * pCurThread = GetThreadNULLOk();
if (pCurThread != NULL)
{
pCurThread->dbg_m_cSuspendedThreads ++;
_ASSERTE(pCurThread->dbg_m_cSuspendedThreads > 0);
}
#endif
IncCantAllocCount();
m_ThreadHandleForResume = hThread;
str = STR_Success;
break;
}
else
{
// SuspendThread failed
if ((int)dwSuspendCount != -1)
{
STRESS_LOG1(LF_SYNC, LL_INFO1000, "In Thread::SuspendThread ::SuspendThread returned %x\n", dwSuspendCount);
}
// Our callers generally expect that STR_Failure means that
// the thread has exited.
#ifndef TARGET_UNIX
_ASSERTE(NtCurrentTeb()->LastStatusValue != STATUS_SUSPEND_COUNT_EXCEEDED);
#endif // !TARGET_UNIX
str = STR_Failure;
break;
}
retry:
handleHolder.Release();
LogLockHolder.Release();
if (fOneTryOnly)
{
str = STR_Forbidden;
break;
}
#if defined(_DEBUG)
i64TimestampPrev = i64TimestampCur;
i64TimestampCur = CLRGetTickCount64();
// CLRGetTickCount64() is global per machine (not per CPU, like getTimeStamp()).
// Next ASSERT states that CLRGetTickCount64() is increasing, or has wrapped.
// If it wrapped, the last iteration should have executed faster then 0.5 seconds.
_ASSERTE(i64TimestampCur >= i64TimestampPrev || i64TimestampCur <= 500);
if (i64TimestampCur - i64TimestampStart >= i64TimestampTicksMax)
{
dwSuspendCount = ClrSuspendThread(hThread);
_ASSERTE(!"It takes too long to suspend a thread");
if ((int)dwSuspendCount >= 0)
ClrResumeThread(hThread);
}
#endif // _DEBUG
// Allow the target thread to run in order to make some progress.
// On multi processor machines we saw the suspending thread resuming immediately after the __SwitchToThread()
// because it has another few processors available. As a consequence the target thread was being Resumed and
// Suspended right away, w/o a real chance to make any progress.
if (g_SystemInfo.dwNumberOfProcessors > 1 && (tries++) % 20 != 0)
{
YieldProcessorNormalized(); // play nice on hyperthreaded CPUs
}
else
{
__SwitchToThread(0, ++dwSwitchCount); // don't spin on uniproc machines
}
}
#ifdef PROFILING_SUPPORTED
{
BEGIN_PROFILER_CALLBACK(CORProfilerTrackSuspends());
if (str == STR_Success)
{
(&g_profControlBlock)->RuntimeThreadSuspended((ThreadID)this);
}
END_PROFILER_CALLBACK();
}
#endif // PROFILING_SUPPORTED
if (pdwSuspendCount != NULL)
{
*pdwSuspendCount = dwSuspendCount;
}
_ASSERTE(str != (SuspendThreadResult) -1);
return str;
}
#endif // DISABLE_THREADSUSPEND
// On non-Windows CORECLR platforms remove Thread::ResumeThread support
#ifndef DISABLE_THREADSUSPEND
DWORD Thread::ResumeThread()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
_ASSERTE (m_ThreadHandleForResume != INVALID_HANDLE_VALUE);
//DWORD res = ClrResumeThread(GetThreadHandle());
DWORD res = ClrResumeThread(m_ThreadHandleForResume);
_ASSERTE (res != 0 && "Thread is not previously suspended");
#ifdef _DEBUG_IMPL
_ASSERTE (!m_Creator.IsCurrentThread());
if ((res != (DWORD)-1) && (res != 0))
{
Thread * pCurThread = GetThreadNULLOk();
if (pCurThread != NULL)
{
_ASSERTE(pCurThread->dbg_m_cSuspendedThreads > 0);
pCurThread->dbg_m_cSuspendedThreads --;
_ASSERTE(pCurThread->dbg_m_cSuspendedThreadsWithoutOSLock <= pCurThread->dbg_m_cSuspendedThreads);
}
}
#endif
if (res != (DWORD) -1 && res != 0)
{
DecCantAllocCount();
}
#ifdef PROFILING_SUPPORTED
{
BEGIN_PROFILER_CALLBACK(CORProfilerTrackSuspends());
if ((res != 0) && (res != (DWORD)-1))
{
(&g_profControlBlock)->RuntimeThreadResumed((ThreadID)this);
}
END_PROFILER_CALLBACK();
}
#endif
return res;
}
#endif // DISABLE_THREADSUSPEND
#ifdef _DEBUG
void* forceStackA;
// CheckSuspended
// Checks whether the given thread is currently suspended.
// Note that if we cannot determine the true suspension status
// of the thread, we succeed. Intended to be used in asserts
// in operations that require the target thread to be suspended.
// Arguments:
// pThread - The thread to examine.
// Return value:
// FALSE, if the thread is definitely not suspended.
// TRUE, otherwise.
static inline BOOL CheckSuspended(Thread *pThread)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
DEBUG_ONLY;
}
CONTRACTL_END;
_ASSERTE(GetThreadNULLOk() != pThread);
_ASSERTE(CheckPointer(pThread));
#ifndef DISABLE_THREADSUSPEND
DWORD dwSuspendCount;
Thread::SuspendThreadResult str = pThread->SuspendThread(FALSE, &dwSuspendCount);
forceStackA = &dwSuspendCount;
if (str == Thread::STR_Success)
{
pThread->ResumeThread();
return dwSuspendCount >= 1;
}
#endif // !DISABLE_THREADSUSPEND
return TRUE;
}
#endif //_DEBUG
BOOL EEGetThreadContext(Thread *pThread, CONTEXT *pContext)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
_ASSERTE(CheckSuspended(pThread));
BOOL ret = pThread->GetThreadContext(pContext);
STRESS_LOG6(LF_SYNC, LL_INFO1000, "Got thread context ret = %d EIP = %p ESP = %p EBP = %p, pThread = %p, ContextFlags = 0x%x\n",
ret, GetIP(pContext), GetSP(pContext), GetFP(pContext), pThread, pContext->ContextFlags);
return ret;
}
BOOL EESetThreadContext(Thread *pThread, const CONTEXT *pContext)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
#ifdef TARGET_X86
_ASSERTE(CheckSuspended(pThread));
#endif
BOOL ret = pThread->SetThreadContext(pContext);
STRESS_LOG6(LF_SYNC, LL_INFO1000, "Set thread context ret = %d EIP = %p ESP = %p EBP = %p, pThread = %p, ContextFlags = 0x%x\n",
ret, GetIP((CONTEXT*)pContext), GetSP((CONTEXT*)pContext), GetFP((CONTEXT*)pContext), pThread, pContext->ContextFlags);
return ret;
}
// Context passed down through a stack crawl (see code below).
struct StackCrawlContext
{
enum SCCType
{
SCC_CheckWithinEH = 0x00000001,
SCC_CheckWithinCer = 0x00000002,
};
Thread* pAbortee;
int eType;
BOOL fUnprotectedCode;
BOOL fWithinEHClause;
BOOL fWithinCer;
BOOL fHasManagedCodeOnStack;
BOOL fWriteToStressLog;
BOOL fHaveLatchedCF;
CrawlFrame LatchedCF;
};
// Crawl the stack looking for Thread Abort related information (whether we're executing inside a CER or an error handling clauses
// of some sort).
static StackWalkAction TAStackCrawlCallBackWorker(CrawlFrame* pCf, StackCrawlContext *pData)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
_ASSERTE(pData->eType & (StackCrawlContext::SCC_CheckWithinCer | StackCrawlContext::SCC_CheckWithinEH));
if(pCf->IsFrameless())
{
IJitManager* pJitManager = pCf->GetJitManager();
_ASSERTE(pJitManager);
if (pJitManager && !pData->fHasManagedCodeOnStack)
{
pData->fHasManagedCodeOnStack = TRUE;
}
}
// Get the method for this frame if it exists (might not be a managed method, so check the explicit frame if that's what we're
// looking at).
MethodDesc *pMD = pCf->GetFunction();
Frame *pFrame = pCf->GetFrame();
if (pMD == NULL && pFrame != NULL)
pMD = pFrame->GetFunction();
// Non-method frames don't interest us.
if (pMD == NULL)
return SWA_CONTINUE;
#if defined(_DEBUG)
#define METHODNAME(pFunc) (pFunc?pFunc->m_pszDebugMethodName:"<n/a>")
#else
#define METHODNAME(pFunc) "<n/a>"
#endif
if (pData->fWriteToStressLog)
{
STRESS_LOG5(LF_EH, LL_INFO100, "TAStackCrawlCallBack: STACKCRAWL method:%pM ('%s'), offset %x, Frame:%p, FrameVtable = %pV\n",
pMD, METHODNAME(pMD), pCf->IsFrameless()?pCf->GetRelOffset():0, pFrame, pCf->IsFrameless()?0:(*(void**)pFrame));
}
#undef METHODNAME
// If we weren't asked about EH clauses then we can return now (stop the stack trace if we have a definitive answer on the CER
// question, move to the next frame otherwise).
if ((pData->eType & StackCrawlContext::SCC_CheckWithinEH) == 0)
return ((pData->fWithinCer || pData->fUnprotectedCode) && pData->fHasManagedCodeOnStack) ? SWA_ABORT : SWA_CONTINUE;
// If we already discovered we're within an EH clause but are still processing (presumably to determine whether we're within a
// CER), then we can just skip to the next frame straight away. Also terminate here if the current frame is not frameless since
// there isn't any useful EH information for non-managed frames.
if (pData->fWithinEHClause || !pCf->IsFrameless())
return SWA_CONTINUE;
IJitManager* pJitManager = pCf->GetJitManager();
_ASSERTE(pJitManager);
EH_CLAUSE_ENUMERATOR pEnumState;
unsigned EHCount = pJitManager->InitializeEHEnumeration(pCf->GetMethodToken(), &pEnumState);
if (EHCount == 0)
// We do not have finally clause here.
return SWA_CONTINUE;
DWORD offs = (DWORD)pCf->GetRelOffset();
if (!pCf->IsActiveFrame())
{
// If we aren't the topmost method, then our IP is a return address and
// we can't use it to directly compare against the EH ranges because we
// may be in an cloned finally which has a call as the last instruction.
offs--;
}
if (pData->fWriteToStressLog)
{
STRESS_LOG1(LF_EH, LL_INFO100, "TAStackCrawlCallBack: STACKCRAWL Offset 0x%x V\n", offs);
}
EE_ILEXCEPTION_CLAUSE EHClause;
StackWalkAction action = SWA_CONTINUE;
#ifndef FEATURE_EH_FUNCLETS
// On X86, the EH encoding for catch clause is completely mess.
// If catch clause is in its own basic block, the end of catch includes everything in the basic block.
// For nested catch, the end of catch may include several jmp instructions after JIT_EndCatch call.
// To better decide if we are inside a nested catch, we check if offs-1 is in more than one catch clause.
DWORD countInCatch = 0;
BOOL fAtJitEndCatch = FALSE;
if (pData->pAbortee == GetThread() &&
pData->pAbortee->ThrewControlForThread() == Thread::InducedThreadRedirectAtEndOfCatch &&
GetControlPC(pCf->GetRegisterSet()) == (PCODE)GetIP(pData->pAbortee->GetAbortContext()))
{
fAtJitEndCatch = TRUE;
offs -= 1;
}
#endif // !FEATURE_EH_FUNCLETS
for(ULONG i=0; i < EHCount; i++)
{
pJitManager->GetNextEHClause(&pEnumState, &EHClause);
_ASSERTE(IsValidClause(&EHClause));
// !!! If this function is called on Aborter thread, we should check for finally only.
// !!! If this function is called on Aborter thread, we should check for finally only.
// !!! Catch and filter clause are skipped. In UserAbort, the first thing after ReadyForAbort
// !!! is to check if the target thread is processing exception.
// !!! If exception is in flight, we don't induce ThreadAbort. Instead at the end of Jit_EndCatch
// !!! we will handle abort.
if (pData->pAbortee != GetThreadNULLOk() && !IsFaultOrFinally(&EHClause))
{
continue;
}
if (offs >= EHClause.HandlerStartPC &&
offs < EHClause.HandlerEndPC)
{
#ifndef FEATURE_EH_FUNCLETS
if (fAtJitEndCatch)
{
// On X86, JIT's EH info may include the instruction after JIT_EndCatch inside the same catch
// clause if it is in the same basic block.
// So for this case, the offs is in at least one catch handler, but since we are at the end of
// catch, this one should not be counted.
countInCatch ++;
if (countInCatch == 1)
{
continue;
}
}
#endif // !FEATURE_EH_FUNCLETS
pData->fWithinEHClause = true;
// We're within an EH clause. If we're asking about CERs too then stop the stack walk if we've reached a conclusive
// result or continue looking otherwise. Else we can stop the stackwalk now.
if (pData->eType & StackCrawlContext::SCC_CheckWithinCer)
{
action = (pData->fWithinCer || pData->fUnprotectedCode) ? SWA_ABORT : SWA_CONTINUE;
}
else
{
action = SWA_ABORT;
}
break;
}
}
#ifndef FEATURE_EH_FUNCLETS
#ifdef _DEBUG
if (fAtJitEndCatch)
{
_ASSERTE (countInCatch > 0);
}
#endif // _DEBUG
#endif // !FEATURE_EH_FUNCLETS
return action;
}
// Wrapper around code:TAStackCrawlCallBackWorker that abstracts away the differences between the reporting order
// of x86 and 64-bit stackwalker implementations, and also deals with interop calls that have an implicit reliability
// contract. If a P/Invoke or CLR->COM call returns SafeHandle or CriticalHandle, the IL stub could be aborted
// before having a chance to store the native handle into the Safe/CriticalHandle object. Therefore such calls are
// treated as unbreakable by convention.
StackWalkAction TAStackCrawlCallBack(CrawlFrame* pCf, void* data)
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
StackCrawlContext *pData = (StackCrawlContext *)data;
// We have the current frame in pCf and possibly one latched frame in pData->LatchedCF. This enumeration
// describes which of these should be passed to code:TAStackCrawlCallBackWorker and in what order.
enum LatchedFrameAction
{
DiscardLatchedFrame, // forget the latched frame, report the current one
DiscardCurrentFrame, // ignore the current frame, report the latched one
ProcessLatchedInOrder, // report the latched frame, then report the current frame
ProcessLatchedReversed, // report the current frame, then report the latched frame
LatchCurrentFrame // latch the current frame, don't report anything
}
frameAction = DiscardLatchedFrame;
#ifdef TARGET_X86
// On X86 the IL stub method is reported to us before the frame with the actual interop method. We need to
// swap the order because if the worker saw the IL stub - which is a CER root - first, it would terminate the
// stack walk and wouldn't allow the thread to be aborted, regardless of how the interop method is annotated.
if (pData->fHaveLatchedCF)
{
// Does the current and latched frame represent the same call?
if (pCf->pFrame == pData->LatchedCF.pFrame)
{
// Report the interop method (current frame) which may be annotated, then the IL stub.
frameAction = ProcessLatchedReversed;
}
else
{
// The two frames are unrelated - process them in order.
frameAction = ProcessLatchedInOrder;
}
pData->fHaveLatchedCF = FALSE;
}
else
{
MethodDesc *pMD = pCf->GetFunction();
if (pMD != NULL && pMD->IsILStub() && InlinedCallFrame::FrameHasActiveCall(pCf->pFrame))
{
// This may be IL stub for an interesting interop call - latch it.
frameAction = LatchCurrentFrame;
}
}
#else // TARGET_X86
// On 64-bit the IL stub method is reported after the actual interop method so we don't have to swap them.
// However, we still want to discard the interop method frame if the call is unbreakable by convention.
if (pData->fHaveLatchedCF)
{
frameAction = ProcessLatchedInOrder;
pData->fHaveLatchedCF = FALSE;
}
else
{
MethodDesc *pMD = pCf->GetFunction();
if (pCf->GetFrame() != NULL && pMD != NULL && (pMD->IsNDirect() || pMD->IsComPlusCall()))
{
// This may be interop method of an interesting interop call - latch it.
frameAction = LatchCurrentFrame;
}
}
#endif // TARGET_X86
// Execute the "frame action".
StackWalkAction action;
switch (frameAction)
{
case DiscardLatchedFrame:
action = TAStackCrawlCallBackWorker(pCf, pData);
break;
case DiscardCurrentFrame:
action = TAStackCrawlCallBackWorker(&pData->LatchedCF, pData);
break;
case ProcessLatchedInOrder:
action = TAStackCrawlCallBackWorker(&pData->LatchedCF, pData);
if (action == SWA_CONTINUE)
action = TAStackCrawlCallBackWorker(pCf, pData);
break;
case ProcessLatchedReversed:
action = TAStackCrawlCallBackWorker(pCf, pData);
if (action == SWA_CONTINUE)
action = TAStackCrawlCallBackWorker(&pData->LatchedCF, pData);
break;
case LatchCurrentFrame:
pData->LatchedCF = *pCf;
pData->fHaveLatchedCF = TRUE;
action = SWA_CONTINUE;
break;
default:
UNREACHABLE();
}
return action;
}
// Is the current thread currently executing within a constrained execution region?
BOOL Thread::IsExecutingWithinCer()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
if (!g_fEEStarted)
return FALSE;
Thread *pThread = GetThread();
StackCrawlContext sContext = { pThread,
StackCrawlContext::SCC_CheckWithinCer,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE,
FALSE};
pThread->StackWalkFrames(TAStackCrawlCallBack, &sContext);
#ifdef STRESS_LOG
if (sContext.fWithinCer && StressLog::StressLogOn(~0u, 0))
{
// If stress log is on, write info to stress log
StackCrawlContext sContext1 = { pThread,
StackCrawlContext::SCC_CheckWithinCer,
FALSE,
FALSE,
FALSE,
FALSE,
TRUE,
FALSE};
pThread->StackWalkFrames(TAStackCrawlCallBack, &sContext1);
}
#endif
return sContext.fWithinCer;
}
#if defined(TARGET_AMD64) && defined(FEATURE_HIJACK)
BOOL Thread::IsSafeToInjectThreadAbort(PTR_CONTEXT pContextToCheck)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(pContextToCheck != NULL);
}
CONTRACTL_END;
EECodeInfo codeInfo(GetIP(pContextToCheck));
_ASSERTE(codeInfo.IsValid());
// Check if the method uses a frame register. If it does not, then RSP will be used by the OS as the frame register
// and returned as the EstablisherFrame. This is fine at any instruction in the method (including epilog) since there is always a
// difference of stackslot size between the callerSP and the callee SP due to return address having been pushed on the stack.
if (!codeInfo.HasFrameRegister())
{
return TRUE;
}
BOOL fSafeToInjectThreadAbort = TRUE;
if (IsIPInEpilog(pContextToCheck, &codeInfo, &fSafeToInjectThreadAbort))
{
return fSafeToInjectThreadAbort;
}
else
{
return TRUE;
}
}
#endif // defined(TARGET_AMD64) && defined(FEATURE_HIJACK)
#ifdef TARGET_AMD64
// CONTEXT_CONTROL does not include any nonvolatile registers that might be the frame pointer.
#define CONTEXT_MIN_STACKWALK (CONTEXT_CONTROL | CONTEXT_INTEGER)
#else
#define CONTEXT_MIN_STACKWALK (CONTEXT_CONTROL)
#endif
BOOL Thread::ReadyForAsyncException()
{
CONTRACTL {
NOTHROW;
GC_NOTRIGGER;
}
CONTRACTL_END;
if (!IsAbortRequested())
{
return FALSE;
}
if (GetThreadNULLOk() == this && HasThreadStateNC (TSNC_PreparingAbort) && !IsRudeAbort() )
{
STRESS_LOG0(LF_APPDOMAIN, LL_INFO10, "in Thread::ReadyForAbort PreparingAbort\n");
// Avoid recursive call
return FALSE;
}
// The thread requests not to be aborted. Honor this for safe abort.
if (!IsRudeAbort() && IsAsyncPrevented())
{
STRESS_LOG0(LF_APPDOMAIN, LL_INFO10, "in Thread::ReadyForAbort AsyncPrevented\n");
return FALSE;
}
REGDISPLAY rd;
Frame *pStartFrame = NULL;
if (ThrewControlForThread() == Thread::InducedThreadRedirect ||
ThrewControlForThread() == Thread::InducedThreadRedirectAtEndOfCatch)
{
_ASSERTE(GetThread() == this);
_ASSERTE(ExecutionManager::IsManagedCode(GetIP(m_OSContext)));
FillRegDisplay(&rd, m_OSContext);
if (ThrewControlForThread() == Thread::InducedThreadRedirectAtEndOfCatch)
{
// On 64bit, this function may be called from COMPlusCheckForAbort when
// stack has not unwound, but m_OSContext points to the place after unwind.
//
TADDR sp = GetSP(m_OSContext);
Frame *pFrameAddr = m_pFrame;
while (pFrameAddr < (LPVOID)sp)
{
pFrameAddr = pFrameAddr->Next();
}
if (pFrameAddr != m_pFrame)
{
pStartFrame = pFrameAddr;
}
}
#if defined(TARGET_AMD64) && defined(FEATURE_HIJACK)
else if (ThrewControlForThread() == Thread::InducedThreadRedirect)
{
if (!IsSafeToInjectThreadAbort(m_OSContext))
{
STRESS_LOG0(LF_EH, LL_INFO10, "Thread::ReadyForAbort: Not injecting abort since we are at an unsafe instruction.\n");
return FALSE;
}
}