Merge pull request #16636 from unknownbrackets/exception-safety

Crash: Ensure we never handle faults in faults

Core/MIPS/ARM64/Arm64Jit.cpp

@@ -427,12 +427,20 @@ bool Arm64Jit::DescribeCodePtr(const u8 *ptr, std::string &name) {
 		name = "loadStaticRegisters";
 	else {
 		u32 addr = blocks.GetAddressFromBlockPtr(ptr);
-		std::vector<int> numbers;
-		blocks.GetBlockNumbersFromAddress(addr, &numbers);
-		if (!numbers.empty()) {
-			const JitBlock *block = blocks.GetBlock(numbers[0]);
+		// Returns 0 when it's valid, but unknown.
+		if (addr == 0) {
+			name = "(unknown or deleted block)";
+			return true;
+		} else if (addr != (u32)-1) {
+			name = "(outside space)";
+			return true;
+		}
+
+		int number = blocks.GetBlockNumberFromAddress(addr);
+		if (number != -1) {
+			const JitBlock *block = blocks.GetBlock(number);
 			if (block) {
-				name = StringFromFormat("(block %d at %08x)", numbers[0], block->originalAddress);
+				name = StringFromFormat("(block %d at %08x)", number, block->originalAddress);
 				return true;
 			}
 		}

Core/MIPS/JitCommon/JitBlockCache.cpp

@@ -375,6 +375,15 @@ void JitBlockCache::GetBlockNumbersFromAddress(u32 em_address, std::vector<int>
 			block_numbers->push_back(i);
 }
 
+int JitBlockCache::GetBlockNumberFromAddress(u32 em_address) {
+	for (int i = 0; i < num_blocks_; i++) {
+		if (blocks_[i].ContainsAddress(em_address))
+			return i;
+	}
+
+	return -1;
+}
+
 u32 JitBlockCache::GetAddressFromBlockPtr(const u8 *ptr) const {
 	if (!codeBlock_->IsInSpace(ptr))
 		return (u32)-1;

Core/MIPS/JitCommon/JitBlockCache.h

@@ -143,6 +143,8 @@ public:
 	// Returns a list of block numbers - only one block can start at a particular address, but they CAN overlap.
 	// This one is slow so should only be used for one-shots from the debugger UI, not for anything during runtime.
 	void GetBlockNumbersFromAddress(u32 em_address, std::vector<int> *block_numbers);
+	// Similar to above, but only the first matching address.
+	int GetBlockNumberFromAddress(u32 em_address);
 	int GetBlockNumberFromEmuHackOp(MIPSOpcode inst, bool ignoreBad = false) const;
 
 	u32 GetAddressFromBlockPtr(const u8 *ptr) const;

Core/MemFault.cpp

@@ -44,6 +44,7 @@ namespace Memory {
 static int64_t g_numReportedBadAccesses = 0;
 const uint8_t *g_lastCrashAddress;
 MemoryExceptionType g_lastMemoryExceptionType;
+static bool inCrashHandler = false;
 
 std::unordered_set<const uint8_t *> g_ignoredAddresses;
 
@@ -88,6 +89,10 @@ static bool DisassembleNativeAt(const uint8_t *codePtr, int instructionSize, std
 }
 
 bool HandleFault(uintptr_t hostAddress, void *ctx) {
+	if (inCrashHandler)
+		return false;
+	inCrashHandler = true;
+
 	SContext *context = (SContext *)ctx;
 	const uint8_t *codePtr = (uint8_t *)(context->CTX_PC);
 
@@ -100,6 +105,7 @@ bool HandleFault(uintptr_t hostAddress, void *ctx) {
 	bool inJitSpace = MIPSComp::jit && MIPSComp::jit->CodeInRange(codePtr);
 	if (!inJitSpace) {
 		// This is a crash in non-jitted code. Not something we want to handle here, ignore.
+		inCrashHandler = false;
 		return false;
 	}
 
@@ -114,8 +120,10 @@ bool HandleFault(uintptr_t hostAddress, void *ctx) {
 	bool invalidHostAddress = hostAddress == (uintptr_t)0xFFFFFFFFFFFFFFFFULL;
 	if (hostAddress < baseAddress || hostAddress >= baseAddress + addressSpaceSize) {
 		// Host address outside - this was a different kind of crash.
-		if (!invalidHostAddress)
+		if (!invalidHostAddress) {
+			inCrashHandler = false;
 			return false;
+		}
 	}
 
 
@@ -182,6 +190,7 @@ bool HandleFault(uintptr_t hostAddress, void *ctx) {
 		// Redirect execution to a crash handler that will switch to CoreState::CORE_RUNTIME_ERROR immediately.
 		context->CTX_PC = (uintptr_t)MIPSComp::jit->GetCrashHandler();
 		ERROR_LOG(MEMMAP, "Bad execution access detected, halting: %08x (last known pc %08x, host: %p)", targetAddr, currentMIPS->pc, (void *)hostAddress);
+		inCrashHandler = false;
 		return true;
 	} else if (success) {
 		if (info.isMemoryWrite) {
@@ -218,6 +227,8 @@ bool HandleFault(uintptr_t hostAddress, void *ctx) {
 		context->CTX_PC = (uintptr_t)MIPSComp::jit->GetCrashHandler();
 		ERROR_LOG(MEMMAP, "Bad memory access detected! %08x (%p) Stopping emulation. Info:\n%s", guestAddress, (void *)hostAddress, infoString.c_str());
 	}
+
+	inCrashHandler = false;
 	return true;
 }
 

UI/DevScreens.cpp

@@ -1145,13 +1145,7 @@ UI::EventReturn JitCompareScreen::OnCurrentBlock(UI::EventParams &e) {
 	JitBlockCache *blockCache = MIPSComp::jit->GetBlockCache();
 	if (!blockCache)
 		return UI::EVENT_DONE;
-	std::vector<int> blockNum;
-	blockCache->GetBlockNumbersFromAddress(currentMIPS->pc, &blockNum);
-	if (blockNum.size() > 0) {
-		currentBlock_ = blockNum[0];
-	} else {
-		currentBlock_ = -1;
-	}
+	currentBlock_ = blockCache->GetBlockNumberFromAddress(currentMIPS->pc);
 	UpdateDisasm();
 	return UI::EVENT_DONE;
 }