fix: correclty report pagefaults while single-stepping or resuming bp

- while resuming threads - after checking threads stopped immediately
check for FE bit, if set do not generate thread stop event
- if PageFault occured, report stop event based on pagefault event

Related-To: GSD-7316

Signed-off-by: Mateusz Hoppe <[email protected]>

Author: HoppeMateusz

level_zero/tools/source/debug/linux/prelim/debug_session.cpp

@@ -1558,6 +1558,22 @@ int DebugSessionLinuxi915::threadControl(const std::vector<EuThread::ThreadId> &
     return euControlRetVal;
 }
 
+bool DebugSessionLinuxi915::checkForceExceptionBit(uint64_t memoryHandle, EuThread::ThreadId threadId, uint32_t *cr0, const SIP::regset_desc *regDesc) {
+
+    auto gpuVa = getContextStateSaveAreaGpuVa(memoryHandle);
+    auto threadSlotOffset = calculateThreadSlotOffset(threadId);
+    auto startRegOffset = threadSlotOffset + calculateRegisterOffsetInThreadSlot(regDesc, 0);
+
+    [[maybe_unused]] int ret = readGpuMemory(memoryHandle, reinterpret_cast<char *>(cr0), 1 * regDesc->bytes, gpuVa + startRegOffset);
+    DEBUG_BREAK_IF(ret != ZE_RESULT_SUCCESS);
+
+    const uint32_t cr0ForcedExcpetionBitmask = 0x04000000;
+    if (cr0[1] & cr0ForcedExcpetionBitmask) {
+        return true;
+    }
+    return false;
+}
+
 void DebugSessionLinuxi915::checkStoppedThreadsAndGenerateEvents(const std::vector<EuThread::ThreadId> &threads, uint64_t memoryHandle, uint32_t deviceIndex) {
 
     std::vector<EuThread::ThreadId> threadsWithAttention;
@@ -1588,19 +1604,30 @@ void DebugSessionLinuxi915::checkStoppedThreadsAndGenerateEvents(const std::vect
     const auto &threadsToCheck = threadsWithAttention.size() > 0 ? threadsWithAttention : threads;
     stoppedThreadsToReport.reserve(threadsToCheck.size());
 
+    const auto regSize = std::max(getRegisterSize(ZET_DEBUG_REGSET_TYPE_CR_INTEL_GPU), 64u);
+    auto cr0 = std::make_unique<uint32_t[]>(regSize / sizeof(uint32_t));
+    auto regDesc = typeToRegsetDesc(ZET_DEBUG_REGSET_TYPE_CR_INTEL_GPU);
+
     for (auto &threadId : threadsToCheck) {
         SIP::sr_ident srMagic = {{0}};
         srMagic.count = 0;
 
         if (readSystemRoutineIdent(allThreads[threadId].get(), memoryHandle, srMagic)) {
             bool wasStopped = allThreads[threadId]->isStopped();
+            bool checkIfStopped = true;
 
-            if (allThreads[threadId]->verifyStopped(srMagic.count)) {
+            if (srMagic.count % 2 == 1) {
+                memset(cr0.get(), 0, regSize);
+                checkIfStopped = !checkForceExceptionBit(memoryHandle, threadId, cr0.get(), regDesc);
+            }
+
+            if (checkIfStopped && allThreads[threadId]->verifyStopped(srMagic.count)) {
                 allThreads[threadId]->stopThread(memoryHandle);
                 if (!wasStopped) {
                     stoppedThreadsToReport.push_back(threadId);
                 }
             }
+
         } else {
             break;
         }

level_zero/tools/source/debug/linux/prelim/debug_session.h

@@ -189,6 +189,7 @@ struct DebugSessionLinuxi915 : DebugSessionLinux {
     ze_result_t resumeImp(const std::vector<EuThread::ThreadId> &threads, uint32_t deviceIndex) override;
     ze_result_t interruptImp(uint32_t deviceIndex) override;
     void checkStoppedThreadsAndGenerateEvents(const std::vector<EuThread::ThreadId> &threads, uint64_t memoryHandle, uint32_t deviceIndex) override;
+    MOCKABLE_VIRTUAL bool checkForceExceptionBit(uint64_t memoryHandle, EuThread::ThreadId threadId, uint32_t *cr0, const SIP::regset_desc *regDesc);
 
     void enqueueApiEvent(zet_debug_event_t &debugEvent) override {
         pushApiEvent(debugEvent);

level_zero/tools/test/unit_tests/sources/debug/linux/prelim/debug_session_fixtures_linux.h

@@ -439,6 +439,13 @@ struct MockDebugSessionLinuxi915 : public L0::DebugSessionLinuxi915 {
         return L0::DebugSessionLinuxi915::checkThreadIsResumed(threadID);
     }
 
+    bool checkForceExceptionBit(uint64_t memoryHandle, EuThread::ThreadId threadId, uint32_t *cr0, const SIP::regset_desc *regDesc) override {
+        if (skipCheckForceExceptionBit) {
+            return false;
+        }
+        return L0::DebugSessionLinuxi915::checkForceExceptionBit(memoryHandle, threadId, cr0, regDesc);
+    }
+
     float getThreadStartLimitTime() override {
         if (threadStartLimit >= 0.0) {
             return threadStartLimit;
@@ -501,6 +508,7 @@ struct MockDebugSessionLinuxi915 : public L0::DebugSessionLinuxi915 {
     uint32_t writeResumeCommandCalled = 0;
     bool skipcheckThreadIsResumed = true;
     uint32_t checkThreadIsResumedCalled = 0;
+    bool skipCheckForceExceptionBit = false;
     uint32_t interruptedDevice = std::numeric_limits<uint32_t>::max();
     uint32_t processPendingVmBindEventsCalled = 0;
     uint32_t checkStoppedThreadsAndGenerateEventsCallCount = 0;

level_zero/tools/test/unit_tests/sources/debug/linux/prelim/test_debug_api_linux.cpp

@@ -5418,15 +5418,23 @@ TEST_F(DebugApiLinuxTest, WhenCallingThreadControlForResumeThenProperIoctlsIsCal
 TEST_F(DebugApiLinuxTest, GivenStoppedAndRunningThreadWhenCheckStoppedThreadsAndGenerateEventsCalledThenThreadStoppedEventsGeneratedOnlyForNewlyStoppedThreads) {
     zet_debug_config_t config = {};
     config.pid = 0x1234;
+    const auto memoryHandle = 1u;
 
     auto sessionMock = std::make_unique<MockDebugSessionLinuxi915>(config, device, 10);
     ASSERT_NE(nullptr, sessionMock);
+    SIP::version version = {2, 0, 0};
+    initStateSaveArea(sessionMock->stateSaveAreaHeader, version, device);
 
     auto handler = new MockIoctlHandler;
     sessionMock->ioctlHandler.reset(handler);
+    handler->setPreadMemory(sessionMock->stateSaveAreaHeader.data(), sessionMock->stateSaveAreaHeader.size(), 0x1000);
+
+    DebugSessionLinuxi915::BindInfo cssaInfo = {0x1000, sessionMock->stateSaveAreaHeader.size()};
+    sessionMock->clientHandleToConnection[MockDebugSessionLinuxi915::mockClientHandle]->vmToContextStateSaveAreaBindInfo[memoryHandle] = cssaInfo;
+
     EuThread::ThreadId thread = {0, 0, 0, 0, 0};
     EuThread::ThreadId thread1 = {0, 0, 0, 0, 1};
-    const auto memoryHandle = 1u;
+
     sessionMock->allThreads[thread.packed]->stopThread(memoryHandle);
     sessionMock->allThreads[thread.packed]->reportAsStopped();
 
@@ -5449,7 +5457,7 @@ TEST_F(DebugApiLinuxTest, GivenStoppedAndRunningThreadWhenCheckStoppedThreadsAnd
 
     sessionMock->checkStoppedThreadsAndGenerateEvents(threads, memoryHandle, 0);
 
-    EXPECT_EQ(1, handler->ioctlCalled);
+    EXPECT_EQ(3, handler->ioctlCalled);
     EXPECT_EQ(1u, handler->euControlArgs.size());
     EXPECT_EQ(2u, sessionMock->numThreadsPassedToThreadControl);
     EXPECT_EQ(uint32_t(PRELIM_I915_DEBUG_EU_THREADS_CMD_STOPPED), handler->euControlArgs[0].euControl.cmd);
@@ -5471,6 +5479,61 @@ TEST_F(DebugApiLinuxTest, GivenStoppedAndRunningThreadWhenCheckStoppedThreadsAnd
     EXPECT_EQ(thread1.thread, event.info.thread.thread.thread);
 }
 
+TEST_F(DebugApiLinuxTest, GivenStoppedThreadResumeCausingPageFaultAndFEBitSetWhenCheckStoppedThreadsAndGenerateEventsCalledThenThreadStoppedEventIsNotGenerated) {
+    zet_debug_config_t config = {};
+    config.pid = 0x1234;
+    const auto memoryHandle = 1u;
+
+    auto sessionMock = std::make_unique<MockDebugSessionLinuxi915>(config, device, 10);
+    ASSERT_NE(nullptr, sessionMock);
+    SIP::version version = {2, 0, 0};
+    initStateSaveArea(sessionMock->stateSaveAreaHeader, version, device);
+
+    auto handler = new MockIoctlHandler;
+    sessionMock->ioctlHandler.reset(handler);
+    handler->setPreadMemory(sessionMock->stateSaveAreaHeader.data(), sessionMock->stateSaveAreaHeader.size(), 0x1000);
+
+    DebugSessionLinuxi915::BindInfo cssaInfo = {0x1000, sessionMock->stateSaveAreaHeader.size()};
+    sessionMock->clientHandleToConnection[MockDebugSessionLinuxi915::mockClientHandle]->vmToContextStateSaveAreaBindInfo[memoryHandle] = cssaInfo;
+
+    EuThread::ThreadId thread = {0, 0, 0, 0, 0};
+
+    sessionMock->allThreads[thread.packed]->stopThread(memoryHandle);
+    sessionMock->allThreads[thread.packed]->reportAsStopped();
+    sessionMock->allThreads[thread.packed]->resumeThread();
+    std::vector<EuThread::ThreadId> threads;
+    threads.push_back(thread);
+
+    for (auto thread : threads) {
+        sessionMock->stoppedThreads[thread.packed] = 3;
+    }
+
+    auto regDesc = sessionMock->typeToRegsetDesc(ZET_DEBUG_REGSET_TYPE_CR_INTEL_GPU);
+    uint32_t cr0[2] = {};
+    cr0[1] = 1 << 26;
+
+    memcpy_s(sessionMock->stateSaveAreaHeader.data() +
+                 threadSlotOffset(reinterpret_cast<SIP::StateSaveAreaHeader *>(sessionMock->stateSaveAreaHeader.data()), thread.slice, thread.subslice, thread.eu, thread.thread) +
+                 regOffsetInThreadSlot(regDesc, 0),
+             regDesc->bytes, cr0, sizeof(cr0));
+
+    std::unique_ptr<uint8_t[]> bitmask;
+    size_t bitmaskSize = 0;
+    auto &hwInfo = neoDevice->getHardwareInfo();
+    auto &l0GfxCoreHelper = neoDevice->getRootDeviceEnvironment().getHelper<L0GfxCoreHelper>();
+    l0GfxCoreHelper.getAttentionBitmaskForSingleThreads(threads, hwInfo, bitmask, bitmaskSize);
+
+    handler->outputBitmaskSize = bitmaskSize;
+    handler->outputBitmask = std::move(bitmask);
+
+    sessionMock->checkStoppedThreadsAndGenerateEvents(threads, memoryHandle, 0);
+
+    EXPECT_EQ(1, handler->ioctlCalled);
+
+    EXPECT_FALSE(sessionMock->allThreads[thread.packed]->isStopped());
+    EXPECT_EQ(0u, sessionMock->apiEvents.size());
+}
+
 TEST_F(DebugApiLinuxTest, GivenNoAttentionBitsWhenMultipleThreadsPassedToCheckStoppedThreadsAndGenerateEventsThenThreadsStateNotCheckedAndEventsNotGenerated) {
     zet_debug_config_t config = {};
     config.pid = 0x1234;
@@ -5547,6 +5610,7 @@ TEST_F(DebugApiLinuxTest, GivenNoAttentionBitsWhenSingleThreadPassedToCheckStopp
 
     handler->outputBitmaskSize = bitmaskSize;
     handler->outputBitmask = std::move(bitmask);
+    sessionMock->skipCheckForceExceptionBit = true;
 
     sessionMock->checkStoppedThreadsAndGenerateEvents({thread1}, memoryHandle, 0);