Common: Tidy up signal handlers

Move MacOS into its own file.
Fix assertion failure crash dumping.

cmake/SearchForStuff.cmake

@@ -69,7 +69,7 @@ else()
 			find_package(Wayland REQUIRED Egl)
 		endif()
 
-		find_package(Libbacktrace)
+		find_package(Libbacktrace REQUIRED)
 		find_package(PkgConfig REQUIRED)
 		pkg_check_modules(DBUS REQUIRED dbus-1)
 	endif()

common/CMakeLists.txt

@@ -44,15 +44,6 @@ target_sources(common PRIVATE
 	emitter/movs.cpp
 	emitter/simd.cpp
 	emitter/x86emitter.cpp
-	Darwin/DarwinThreads.cpp
-	Darwin/DarwinMisc.cpp
-	Darwin/DarwinSemaphore.cpp
-	Linux/LnxHostSys.cpp
-	Linux/LnxThreads.cpp
-	Linux/LnxMisc.cpp
-	Windows/WinThreads.cpp
-	Windows/WinHostSys.cpp
-	Windows/WinMisc.cpp
 )
 
 # x86emitter headers
@@ -124,34 +115,32 @@ target_sources(common PRIVATE
 	emitter/legacy_types.h
 	emitter/x86emitter.h
 	emitter/x86types.h
-	Darwin/DarwinMisc.h
 )
 
-set_source_files_properties(PrecompiledHeader.cpp PROPERTIES HEADER_FILE_ONLY TRUE)
-
-if(USE_VTUNE)
-	target_link_libraries(common PUBLIC Vtune::Vtune)
-endif()
-
 if(WIN32)
 	enable_language(ASM_MASM)
-	target_sources(common PRIVATE FastJmp.asm)
-	target_link_libraries(common PUBLIC WIL::WIL winmm pathcch)
 	target_sources(common PRIVATE
-		CrashHandler.cpp
-		CrashHandler.h
 		FastJmp.asm
 		HTTPDownloaderWinHTTP.cpp
 		HTTPDownloaderWinHTTP.h
 		StackWalker.cpp
 		StackWalker.h
+		Windows/WinThreads.cpp
+		Windows/WinHostSys.cpp
+		Windows/WinMisc.cpp
 	)
-endif()
+	target_link_libraries(common PUBLIC
-
+		WIL::WIL
-if(APPLE)
+		winmm
+		pathcch
+	)
+elseif(APPLE)
 	target_sources(common PRIVATE
 		CocoaTools.mm
 		CocoaTools.h
+		Darwin/DarwinThreads.cpp
+		Darwin/DarwinMisc.cpp
+		Darwin/DarwinMisc.h
 	)
 	target_compile_options(common PRIVATE -fobjc-arc)
 	target_link_options(common PRIVATE -fobjc-link-runtime)
@@ -159,15 +148,27 @@ if(APPLE)
 		"-framework Foundation"
 		"-framework IOKit"
 	)
+else()
+	target_sources(common PRIVATE
+		Linux/LnxHostSys.cpp
+		Linux/LnxThreads.cpp
+		Linux/LnxMisc.cpp
+	)
+	target_include_directories(common PRIVATE
+		${DBUS_INCLUDE_DIRS}
+	)
+	target_link_libraries(common PRIVATE
+		${DBUS_LINK_LIBRARIES}
+		libbacktrace::libbacktrace
+		X11::X11
+		X11::Xrandr
+	)
 endif()
 
-if(UNIX AND NOT APPLE)
+set_source_files_properties(PrecompiledHeader.cpp PROPERTIES HEADER_FILE_ONLY TRUE)
-	target_include_directories(common PRIVATE ${DBUS_INCLUDE_DIRS})
+
-	target_link_libraries(common PRIVATE ${DBUS_LINK_LIBRARIES} X11::X11 X11::Xrandr)
+if(USE_VTUNE)
-  if(TARGET libbacktrace::libbacktrace)
+	target_link_libraries(common PUBLIC Vtune::Vtune)
-		target_compile_definitions(common PRIVATE "HAS_LIBBACKTRACE=1")
-		target_link_libraries(common PRIVATE libbacktrace::libbacktrace)
-  endif()
 endif()
 
 if (USE_GCC AND CMAKE_INTERPROCEDURAL_OPTIMIZATION)
@@ -181,7 +182,9 @@ if(NOT WIN32)
 		HTTPDownloaderCurl.cpp
 		HTTPDownloaderCurl.h
 	)
-	target_link_libraries(common PRIVATE CURL::libcurl)
+	target_link_libraries(common PRIVATE
+		CURL::libcurl
+	)
 endif()
 
 target_link_libraries(common PRIVATE

common/CrashHandler.cpp

@@ -56,23 +56,31 @@ static bool WriteMinidump(HMODULE hDbgHelp, HANDLE hFile, HANDLE hProcess, DWORD
 			PMINIDUMP_EXCEPTION_INFORMATION ExceptionParam, PMINIDUMP_USER_STREAM_INFORMATION UserStreamParam,
 			PMINIDUMP_CALLBACK_INFORMATION CallbackParam);
 
-	PFNMINIDUMPWRITEDUMP minidump_write_dump = hDbgHelp ?
+	PFNMINIDUMPWRITEDUMP minidump_write_dump =
-												   reinterpret_cast<PFNMINIDUMPWRITEDUMP>(GetProcAddress(hDbgHelp, "MiniDumpWriteDump")) :
+		hDbgHelp ? reinterpret_cast<PFNMINIDUMPWRITEDUMP>(GetProcAddress(hDbgHelp, "MiniDumpWriteDump")) : nullptr;
-                                                   nullptr;
 	if (!minidump_write_dump)
 		return false;
 
-	MINIDUMP_EXCEPTION_INFORMATION mei;
+	MINIDUMP_EXCEPTION_INFORMATION mei = {};
-	PMINIDUMP_EXCEPTION_INFORMATION mei_ptr = nullptr;
 	if (exception)
 	{
 		mei.ThreadId = thread_id;
 		mei.ExceptionPointers = exception;
 		mei.ClientPointers = FALSE;
-		mei_ptr = &mei;
+		return minidump_write_dump(hProcess, process_id, hFile, type, &mei, nullptr, nullptr);
 	}
 
-	return minidump_write_dump(hProcess, process_id, hFile, type, mei_ptr, nullptr, nullptr);
+	__try
+	{
+		RaiseException(EXCEPTION_INVALID_HANDLE, 0, 0, nullptr);
+	}
+	__except (WriteMinidump(hDbgHelp, hFile, GetCurrentProcess(), GetCurrentProcessId(), GetCurrentThreadId(),
+				  GetExceptionInformation(), type),
+		EXCEPTION_EXECUTE_HANDLER)
+	{
+	}
+
+	return true;
 }
 
 static std::wstring s_write_directory;
@@ -168,7 +176,7 @@ void CrashHandler::WriteDumpForCaller()
 	WriteMinidumpAndCallstack(nullptr);
 }
 
-#elif defined(HAS_LIBBACKTRACE)
+#elif !defined(__APPLE__)
 
 #include "FileSystem.h"
 
@@ -194,16 +202,13 @@ namespace CrashHandler
 	static void FreeBuffer(BacktraceBuffer* buf);
 	static void AppendToBuffer(BacktraceBuffer* buf, const char* format, ...);
 	static int BacktraceFullCallback(void* data, uintptr_t pc, const char* filename, int lineno, const char* function);
-	static void CallExistingSignalHandler(int signal, siginfo_t* siginfo, void* ctx);
+	static void LogCallstack(int signal, const void* exception_pc);
-	static void CrashSignalHandler(int signal, siginfo_t* siginfo, void* ctx);
 
 	static std::recursive_mutex s_crash_mutex;
 	static bool s_in_signal_handler = false;
 
 	static backtrace_state* s_backtrace_state = nullptr;
-	static struct sigaction s_old_sigbus_action;
+} // namespace CrashHandler
-	static struct sigaction s_old_sigsegv_action;
-}
 
 const char* CrashHandler::GetSignalName(int signal_no)
 {
@@ -214,7 +219,7 @@ const char* CrashHandler::GetSignalName(int signal_no)
 		case SIGSEGV: return "SIGSEGV";
 		case SIGBUS: return "SIGBUS";
 		default: return "UNKNOWN";
-		// clang-format on
+			// clang-format on
 	}
 }
 
@@ -253,7 +258,8 @@ void CrashHandler::AppendToBuffer(BacktraceBuffer* buf, const char* format, ...)
 	va_end(ap);
 }
 
-int CrashHandler::BacktraceFullCallback(void* data, uintptr_t pc, const char* filename, int lineno, const char* function)
+int CrashHandler::BacktraceFullCallback(void* data, uintptr_t pc, const char* filename, int lineno,
+	const char* function)
 {
 	BacktraceBuffer* buf = static_cast<BacktraceBuffer*>(data);
 	AppendToBuffer(buf, "  %016p", pc);
@@ -261,34 +267,36 @@ int CrashHandler::BacktraceFullCallback(void* data, uintptr_t pc, const char* fi
 		AppendToBuffer(buf, " %s", function);
 	if (filename)
 		AppendToBuffer(buf, " [%s:%d]", filename, lineno);
-	
+
 	AppendToBuffer(buf, "\n");
 	return 0;
 }
 
-void CrashHandler::CallExistingSignalHandler(int signal, siginfo_t* siginfo, void* ctx)
+void CrashHandler::LogCallstack(int signal, const void* exception_pc)
 {
-	const struct sigaction& sa = (signal == SIGBUS) ? s_old_sigbus_action : s_old_sigsegv_action;
+	BacktraceBuffer buf;
-	if (sa.sa_flags & SA_SIGINFO)
+	AllocateBuffer(&buf);
-	{
+	if (signal != 0 || exception_pc)
-		sa.sa_sigaction(signal, siginfo, ctx);
+		AppendToBuffer(&buf, "*************** Unhandled %s at %p ***************\n", GetSignalName(signal), exception_pc);
-	}
+	else
-	else if (sa.sa_handler == SIG_DFL)
+		AppendToBuffer(&buf, "*******************************************************************\n");
-	{
+
-		// Re-raising the signal would just queue it, and since we'd restore the handler back to us,
+	const int rc = backtrace_full(s_backtrace_state, 0, BacktraceFullCallback, nullptr, &buf);
-		// we'd end up right back here again. So just abort, because that's probably what it'd do anyway.
+	if (rc != 0)
-		abort();
+		AppendToBuffer(&buf, "  backtrace_full() failed: %d\n");
-	}
+
-	else if (sa.sa_handler != SIG_IGN)
+	AppendToBuffer(&buf, "*******************************************************************\n");
-	{
+
-		sa.sa_handler(signal);
+	if (buf.used > 0)
-	}
+		write(STDERR_FILENO, buf.buffer, buf.used);
+
+	FreeBuffer(&buf);
 }
 
 void CrashHandler::CrashSignalHandler(int signal, siginfo_t* siginfo, void* ctx)
 {
 	std::unique_lock lock(s_crash_mutex);
-	
+
 	// If we crash somewhere in libbacktrace, don't bother trying again.
 	if (!s_in_signal_handler)
 	{
@@ -304,27 +312,17 @@ void CrashHandler::CrashSignalHandler(int signal, siginfo_t* siginfo, void* ctx)
 		void* const exception_pc = nullptr;
 #endif
 
-		BacktraceBuffer buf;
+		LogCallstack(signal, exception_pc);
-		AllocateBuffer(&buf);
-		AppendToBuffer(&buf, "*************** Unhandled %s at %p ***************\n", GetSignalName(signal), exception_pc);
-
-		const int rc = backtrace_full(s_backtrace_state, 0, BacktraceFullCallback, nullptr, &buf);
-		if (rc != 0)
-			AppendToBuffer(&buf, "  backtrace_full() failed: %d\n");
-
-		AppendToBuffer(&buf, "*******************************************************************\n");
-
-		if (buf.used > 0)
-			write(STDERR_FILENO, buf.buffer, buf.used);
-
-		FreeBuffer(&buf);
 
 		s_in_signal_handler = false;
 	}
 
-	// Chances are we're not going to have anything else to call, but just in case.
 	lock.unlock();
-	CallExistingSignalHandler(signal, siginfo, ctx);
+
+	// We can't continue from here. Just bail out and dump core.
+	std::fputs("Aborting application.\n", stderr);
+	std::fflush(stderr);
+	std::abort();
 }
 
 bool CrashHandler::Install()
@@ -333,15 +331,15 @@ bool CrashHandler::Install()
 	s_backtrace_state = backtrace_create_state(progpath.empty() ? nullptr : progpath.c_str(), 0, nullptr, nullptr);
 	if (!s_backtrace_state)
 		return false;
-	
+
 	struct sigaction sa;
 
 	sigemptyset(&sa.sa_mask);
 	sa.sa_flags = SA_SIGINFO | SA_NODEFER;
 	sa.sa_sigaction = CrashSignalHandler;
-	if (sigaction(SIGBUS, &sa, &s_old_sigbus_action) != 0)
+	if (sigaction(SIGBUS, &sa, nullptr) != 0)
 		return false;
-	if (sigaction(SIGSEGV, &sa, &s_old_sigsegv_action) != 0)
+	if (sigaction(SIGSEGV, &sa, nullptr) != 0)
 		return false;
 
 	return true;
@@ -353,6 +351,7 @@ void CrashHandler::SetWriteDirectory(std::string_view dump_directory)
 
 void CrashHandler::WriteDumpForCaller()
 {
+	LogCallstack(0, nullptr);
 }
 
 #else
@@ -370,4 +369,12 @@ void CrashHandler::WriteDumpForCaller()
 {
 }
 
+void CrashHandler::CrashSignalHandler(int signal, siginfo_t* siginfo, void* ctx)
+{
+	// We can't continue from here. Just bail out and dump core.
+	std::fputs("Aborting application.\n", stderr);
+	std::fflush(stderr);
+	std::abort();
+}
+
 #endif

common/CrashHandler.h

@@ -3,9 +3,18 @@
 
 #include <string_view>
 
+#ifndef _WIN32
+#include <csignal>
+#endif
+
 namespace CrashHandler
 {
 	bool Install();
 	void SetWriteDirectory(std::string_view dump_directory);
 	void WriteDumpForCaller();
+
+#ifndef _WIN32
+	// Allow crash handler to be invoked from a signal.
+	void CrashSignalHandler(int signal, siginfo_t* siginfo, void* ctx);
+#endif
 } // namespace CrashHandler

common/Darwin/DarwinMisc.cpp

@@ -1,11 +1,18 @@
 // SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if defined(__APPLE__)
+#include "common/Assertions.h"
-
+#include "common/BitUtils.h"
+#include "common/Console.h"
+#include "common/CrashHandler.h"
 #include "common/Darwin/DarwinMisc.h"
+#include "common/Error.h"
+#include "common/Pcsx2Types.h"
+#include "common/Threading.h"
+#include "common/WindowInfo.h"
 #include "common/HostSys.h"
 
+#include <csignal>
 #include <cstring>
 #include <cstdlib>
 #include <optional>
@@ -17,17 +24,11 @@
 #include <mach/mach_port.h>
 #include <mach/mach_time.h>
 #include <mach/mach_vm.h>
+#include <mach/task.h>
 #include <mach/vm_map.h>
+#include <mutex>
 #include <IOKit/pwr_mgt/IOPMLib.h>
 
-#include "common/Assertions.h"
-#include "common/BitUtils.h"
-#include "common/Console.h"
-#include "common/Pcsx2Types.h"
-#include "common/HostSys.h"
-#include "common/Threading.h"
-#include "common/WindowInfo.h"
-
 // Darwin (OSX) is a bit different from Linux when requesting properties of
 // the OS because of its BSD/Mach heritage. Helpfully, most of this code
 // should translate pretty well to other *BSD systems. (e.g.: the sysctl(3)
@@ -399,6 +400,116 @@ void HostSys::EndCodeWrite()
 		pthread_jit_write_protect_np(1);
 }
 
+[[maybe_unused]] static bool IsStoreInstruction(const void* ptr)
+{
+	u32 bits;
+	std::memcpy(&bits, ptr, sizeof(bits));
+
+	// Based on vixl's disassembler Instruction::IsStore().
+	// if (Mask(LoadStoreAnyFMask) != LoadStoreAnyFixed)
+	if ((bits & 0x0a000000) != 0x08000000)
+		return false;
+
+	// if (Mask(LoadStorePairAnyFMask) == LoadStorePairAnyFixed)
+	if ((bits & 0x3a000000) == 0x28000000)
+	{
+		// return Mask(LoadStorePairLBit) == 0
+		return (bits & (1 << 22)) == 0;
+	}
+
+	switch (bits & 0xC4C00000)
+	{
+		case 0x00000000: // STRB_w
+		case 0x40000000: // STRH_w
+		case 0x80000000: // STR_w
+		case 0xC0000000: // STR_x
+		case 0x04000000: // STR_b
+		case 0x44000000: // STR_h
+		case 0x84000000: // STR_s
+		case 0xC4000000: // STR_d
+		case 0x04800000: // STR_q
+			return true;
+
+		default:
+			return false;
+	}
+}
+
+#endif // _M_ARM64
+
+namespace PageFaultHandler
+{
+	static void SignalHandler(int sig, siginfo_t* info, void* ctx);
+
+	static std::recursive_mutex s_exception_handler_mutex;
+	static bool s_in_exception_handler = false;
+	static bool s_installed = false;
+} // namespace PageFaultHandler
+
+void PageFaultHandler::SignalHandler(int sig, siginfo_t* info, void* ctx)
+{
+#if defined(_M_X86)
+	void* const exception_address =
+		reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__faultvaddr);
+	void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__rip);
+	const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__err & 2) != 0;
+#elif defined(_M_ARM64)
+	void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
+	void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
+	const bool is_write = IsStoreInstruction(exception_pc);
 #endif
 
+	// Executing the handler concurrently from multiple threads wouldn't go down well.
+	s_exception_handler_mutex.lock();
+
+	// Prevent recursive exception filtering.
+	HandlerResult result = HandlerResult::ExecuteNextHandler;
+	if (!s_in_exception_handler)
+	{
+		s_in_exception_handler = true;
+		result = HandlePageFault(exception_pc, exception_address, is_write);
+		s_in_exception_handler = false;
+	}
+
+	s_exception_handler_mutex.unlock();
+
+	// Resumes execution right where we left off (re-executes instruction that caused the SIGSEGV).
+	if (result == HandlerResult::ContinueExecution)
+		return;
+
+	// We couldn't handle it. Pass it off to the crash dumper.
+	CrashHandler::CrashSignalHandler(sig, info, ctx);
+}
+
+bool PageFaultHandler::Install(Error* error)
+{
+	std::unique_lock lock(s_exception_handler_mutex);
+	pxAssertRel(!s_installed, "Page fault handler has already been installed.");
+
+	struct sigaction sa;
+
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = SA_SIGINFO;
+	sa.sa_sigaction = SignalHandler;
+
+	// MacOS uses SIGBUS for memory permission violations, as well as SIGSEGV on ARM64.
+	if (sigaction(SIGBUS, &sa, nullptr) != 0)
+	{
+		Error::SetErrno(error, "sigaction() for SIGBUS failed: ", errno);
+		return false;
+	}
+
+#ifdef _M_ARM64
+	if (sigaction(SIGSEGV, &sa, nullptr) != 0)
+	{
+		Error::SetErrno(error, "sigaction() for SIGSEGV failed: ", errno);
+		return false;
+	}
 #endif
+
+	// Allow us to ignore faults when running under lldb.
+	task_set_exception_ports(mach_task_self(), EXC_MASK_BAD_ACCESS, MACH_PORT_NULL, EXCEPTION_DEFAULT, 0);
+
+	s_installed = true;
+	return true;
+}

common/Darwin/DarwinSemaphore.cpp

@@ -1,71 +0,0 @@
-// SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
-// SPDX-License-Identifier: LGPL-3.0+
-
-#if defined(__APPLE__)
-
-#include <cstdio>
-#include <cassert> // assert
-#include <pthread.h> // pthread_setcancelstate()
-#include <sys/time.h> // gettimeofday()
-#include <mach/mach.h>
-#include <mach/task.h> // semaphore_create() and semaphore_destroy()
-#include <mach/semaphore.h> // semaphore_*()
-#include <mach/mach_error.h> // mach_error_string()
-#include <mach/mach_time.h> // mach_absolute_time()
-
-#include "common/Threading.h"
-
-// --------------------------------------------------------------------------------------
-//  Semaphore Implementation for Darwin/OSX
-//
-//  Sadly, Darwin/OSX needs its own implementation of Semaphores instead of
-//  relying on phtreads, because OSX unnamed semaphore (the best kind)
-//  support is very poor.
-//
-//  This implementation makes use of Mach primitives instead. These are also
-//  what Grand Central Dispatch (GCD) is based on, as far as I understand:
-//  http://newosxbook.com/articles/GCD.html.
-//
-// --------------------------------------------------------------------------------------
-
-static void MACH_CHECK(kern_return_t mach_retval)
-{
-	if (mach_retval != KERN_SUCCESS)
-	{
-		fprintf(stderr, "mach error: %s", mach_error_string(mach_retval));
-		assert(mach_retval == KERN_SUCCESS);
-	}
-}
-
-Threading::KernelSemaphore::KernelSemaphore()
-{
-	MACH_CHECK(semaphore_create(mach_task_self(), &m_sema, SYNC_POLICY_FIFO, 0));
-}
-
-Threading::KernelSemaphore::~KernelSemaphore()
-{
-	MACH_CHECK(semaphore_destroy(mach_task_self(), m_sema));
-}
-
-void Threading::KernelSemaphore::Post()
-{
-	MACH_CHECK(semaphore_signal(m_sema));
-}
-
-void Threading::KernelSemaphore::Wait()
-{
-	MACH_CHECK(semaphore_wait(m_sema));
-}
-
-bool Threading::KernelSemaphore::TryWait()
-{
-	mach_timespec_t time = {};
-	kern_return_t res = semaphore_timedwait(m_sema, time);
-	if (res == KERN_OPERATION_TIMED_OUT)
-		return false;
-	MACH_CHECK(res);
-	return true;
-}
-
-#endif
-

common/Darwin/DarwinThreads.cpp

@@ -1,19 +1,24 @@
-// SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
+// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if defined(__APPLE__)
-
-#include <sched.h>
-#include <pthread.h>
-#include <unistd.h>
-#include <mach/mach_init.h>
-#include <mach/thread_act.h>
-#include <mach/mach_port.h>
-
-#include "common/PrecompiledHeader.h"
 #include "common/Threading.h"
 #include "common/Assertions.h"
 
+#include <cstdio>
+#include <cassert> // assert
+#include <sched.h>
+#include <sys/time.h> // gettimeofday()
+#include <pthread.h>
+#include <unistd.h>
+#include <mach/mach.h>
+#include <mach/mach_error.h> // mach_error_string()
+#include <mach/mach_init.h>
+#include <mach/mach_port.h>
+#include <mach/mach_time.h> // mach_absolute_time()
+#include <mach/semaphore.h> // semaphore_*()
+#include <mach/task.h> // semaphore_create() and semaphore_destroy()
+#include <mach/thread_act.h>
+
 // Note: assuming multicore is safer because it forces the interlocked routines to use
 // the LOCK prefix.  The prefix works on single core CPUs fine (but is slow), but not
 // having the LOCK prefix is very bad indeed.
@@ -89,6 +94,58 @@ u64 Threading::GetThreadCpuTime()
 	return us;
 }
 
+// --------------------------------------------------------------------------------------
+//  Semaphore Implementation for Darwin/OSX
+//
+//  Sadly, Darwin/OSX needs its own implementation of Semaphores instead of
+//  relying on phtreads, because OSX unnamed semaphore (the best kind)
+//  support is very poor.
+//
+//  This implementation makes use of Mach primitives instead. These are also
+//  what Grand Central Dispatch (GCD) is based on, as far as I understand:
+//  http://newosxbook.com/articles/GCD.html.
+//
+// --------------------------------------------------------------------------------------
+
+static void MACH_CHECK(kern_return_t mach_retval)
+{
+	if (mach_retval != KERN_SUCCESS)
+	{
+		fprintf(stderr, "mach error: %s", mach_error_string(mach_retval));
+		assert(mach_retval == KERN_SUCCESS);
+	}
+}
+
+Threading::KernelSemaphore::KernelSemaphore()
+{
+	MACH_CHECK(semaphore_create(mach_task_self(), &m_sema, SYNC_POLICY_FIFO, 0));
+}
+
+Threading::KernelSemaphore::~KernelSemaphore()
+{
+	MACH_CHECK(semaphore_destroy(mach_task_self(), m_sema));
+}
+
+void Threading::KernelSemaphore::Post()
+{
+	MACH_CHECK(semaphore_signal(m_sema));
+}
+
+void Threading::KernelSemaphore::Wait()
+{
+	MACH_CHECK(semaphore_wait(m_sema));
+}
+
+bool Threading::KernelSemaphore::TryWait()
+{
+	mach_timespec_t time = {};
+	kern_return_t res = semaphore_timedwait(m_sema, time);
+	if (res == KERN_OPERATION_TIMED_OUT)
+		return false;
+	MACH_CHECK(res);
+	return true;
+}
+
 Threading::ThreadHandle::ThreadHandle() = default;
 
 Threading::ThreadHandle::ThreadHandle(const ThreadHandle& handle)
@@ -220,5 +277,3 @@ void Threading::SetNameOfCurrentThread(const char* name)
 {
 	pthread_setname_np(name);
 }
-
-#endif

common/HostSys.h

@@ -123,12 +123,18 @@ namespace HostSys
 #else
 	void FlushInstructionCache(void* address, u32 size);
 #endif
-}
+} // namespace HostSys
 
 namespace PageFaultHandler
 {
-	bool HandlePageFault(uptr pc, uptr addr, bool is_write);
+	enum class HandlerResult
-	bool Install(Error* error);
+	{
+		ContinueExecution,
+		ExecuteNextHandler,
+	};
+
+	HandlerResult HandlePageFault(void* exception_pc, void* fault_address, bool is_write);
+	bool Install(Error* error = nullptr);
 } // namespace PageFaultHandler
 
 class SharedMemoryMappingArea

common/Linux/LnxHostSys.cpp

@@ -1,229 +1,30 @@
-// SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
+// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if defined(__APPLE__)
-#define _XOPEN_SOURCE
-#endif
-
-#if !defined(_WIN32)
-#include <cstdio>
-#include <sys/mman.h>
-#include <signal.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <unistd.h>
-
-#include <mutex>
-
-#include "fmt/core.h"
-
 #include "common/Assertions.h"
 #include "common/BitUtils.h"
 #include "common/Console.h"
+#include "common/CrashHandler.h"
 #include "common/Error.h"
 #include "common/HostSys.h"
 
-// Apple uses the MAP_ANON define instead of MAP_ANONYMOUS, but they mean
+#include <cstdio>
-// the same thing.
+#include <csignal>
-#if defined(__APPLE__) && !defined(MAP_ANONYMOUS)
+#include <cerrno>
-#define MAP_ANONYMOUS MAP_ANON
+#include <fcntl.h>
-#endif
+#include <mutex>
+#include <sys/mman.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+#include "fmt/core.h"
 
 // FreeBSD does not have MAP_FIXED_NOREPLACE, but does have MAP_EXCL.
 // MAP_FIXED combined with MAP_EXCL behaves like MAP_FIXED_NOREPLACE.
 #if defined(__FreeBSD__) && !defined(MAP_FIXED_NOREPLACE)
-#define MAP_FIXED_NOREPLACE MAP_FIXED | MAP_EXCL
+#define MAP_FIXED_NOREPLACE (MAP_FIXED | MAP_EXCL)
 #endif
 
-#include <cerrno>
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <unistd.h>
-
-#ifndef __APPLE__
-#include <ucontext.h>
-#endif
-
-static std::recursive_mutex s_exception_handler_mutex;
-static bool s_in_exception_handler = false;
-static bool s_exception_handler_installed = false;
-
-#ifdef __APPLE__
-#include <mach/task.h>
-#include <mach/mach_init.h>
-#include <mach/mach_port.h>
-#endif
-
-#if defined(__APPLE__) || defined(__aarch64__)
-static struct sigaction s_old_sigbus_action;
-#endif
-#if !defined(__APPLE__) || defined(__aarch64__)
-static struct sigaction s_old_sigsegv_action;
-#endif
-
-#ifdef __aarch64__
-[[maybe_unused]] static bool IsStoreInstruction(uptr ptr)
-{
-	u32 bits;
-	std::memcpy(&bits, reinterpret_cast<const void*>(ptr), sizeof(bits));
-
-	// Based on vixl's disassembler Instruction::IsStore().
-	// if (Mask(LoadStoreAnyFMask) != LoadStoreAnyFixed)
-	if ((bits & 0x0a000000) != 0x08000000)
-		return false;
-
-	// if (Mask(LoadStorePairAnyFMask) == LoadStorePairAnyFixed)
-	if ((bits & 0x3a000000) == 0x28000000)
-	{
-		// return Mask(LoadStorePairLBit) == 0
-		return (bits & (1 << 22)) == 0;
-	}
-
-	switch (bits & 0xC4C00000)
-	{
-		case 0x00000000: // STRB_w
-		case 0x40000000: // STRH_w
-		case 0x80000000: // STR_w
-		case 0xC0000000: // STR_x
-		case 0x04000000: // STR_b
-		case 0x44000000: // STR_h
-		case 0x84000000: // STR_s
-		case 0xC4000000: // STR_d
-		case 0x04800000: // STR_q
-			return true;
-
-		default:
-			return false;
-	}
-}
-#endif
-
-static void CallExistingSignalHandler(int signal, siginfo_t* siginfo, void* ctx)
-{
-#if defined(__aarch64__)
-	const struct sigaction& sa = (signal == SIGBUS) ? s_old_sigbus_action : s_old_sigsegv_action;
-#elif defined(__APPLE__)
-	const struct sigaction& sa = s_old_sigbus_action;
-#else
-	const struct sigaction& sa = s_old_sigsegv_action;
-#endif
-
-	if (sa.sa_flags & SA_SIGINFO)
-	{
-		sa.sa_sigaction(signal, siginfo, ctx);
-	}
-	else if (sa.sa_handler == SIG_DFL)
-	{
-		// Re-raising the signal would just queue it, and since we'd restore the handler back to us,
-		// we'd end up right back here again. So just abort, because that's probably what it'd do anyway.
-		abort();
-	}
-	else if (sa.sa_handler != SIG_IGN)
-	{
-		sa.sa_handler(signal);
-	}
-}
-
-// Linux implementation of SIGSEGV handler.  Bind it using sigaction().
-static void SysPageFaultSignalFilter(int signal, siginfo_t* info, void* ctx)
-{
-	// Executing the handler concurrently from multiple threads wouldn't go down well.
-	std::unique_lock lock(s_exception_handler_mutex);
-
-	// Prevent recursive exception filtering.
-	if (s_in_exception_handler)
-	{
-		lock.unlock();
-		CallExistingSignalHandler(signal, info, ctx);
-		return;
-	}
-
-#if defined(__linux__)
-	const uptr exception_address = reinterpret_cast<uptr>(info->si_addr);
-	#if defined(__x86_64__)
-		const uptr exception_pc = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_RIP]);
-		const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_ERR] & 2) != 0;
-	#elif defined(__aarch64__)
-		const uptr exception_pc = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext.pc);
-		const bool is_write = IsStoreInstruction(exception_pc);
-	#endif
-#elif defined(__APPLE__)
-	#if defined(__x86_64__)
-		const uptr exception_pc = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__rip);
-		const uptr exception_address = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__faultvaddr);
-		const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__err & 2) != 0;
-	#elif defined(__aarch64__)
-		const uptr exception_address = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
-		const uptr exception_pc = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
-		const bool is_write = IsStoreInstruction(exception_pc);
-	#endif
-#elif defined(__FreeBSD__)
-	#if defined(__x86_64__)
-		const uptr exception_address = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_addr);
-		const uptr exception_pc = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_rip);
-		const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_err & 2) != 0;
-	#elif defined(__aarch64__)
-		const uptr exception_address = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
-		const uptr exception_pc = static_cast<uptr>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
-		const bool is_write = IsStoreInstruction(exception_pc);
-	#endif
-#endif
-
-	s_in_exception_handler = true;
-
-	const bool handled = PageFaultHandler::HandlePageFault(exception_pc, exception_address, is_write);
-
-	s_in_exception_handler = false;
-
-	// Resumes execution right where we left off (re-executes instruction that caused the SIGSEGV).
-	if (handled)
-		return;
-
-	// Call old signal handler, which will likely dump core.
-	lock.unlock();
-	CallExistingSignalHandler(signal, info, ctx);
-}
-
-bool PageFaultHandler::Install(Error* error)
-{
-	std::unique_lock lock(s_exception_handler_mutex);
-	pxAssertRel(!s_exception_handler_installed, "Page fault handler has already been installed.");
-
-	struct sigaction sa;
-
-	sigemptyset(&sa.sa_mask);
-	sa.sa_flags = SA_SIGINFO;
-	sa.sa_sigaction = SysPageFaultSignalFilter;
-#ifdef __linux__
-	// Don't block the signal from executing recursively, we want to fire the original handler.
-	sa.sa_flags |= SA_NODEFER;
-#endif
-#if defined(__APPLE__) || defined(__aarch64__)
-	// MacOS uses SIGBUS for memory permission violations, as well as SIGSEGV on ARM64.
-	if (sigaction(SIGBUS, &sa, &s_old_sigbus_action) != 0)
-	{
-		Error::SetErrno(error, "sigaction() for SIGSEGV failed: ", errno);
-		return false;
-	}
-#endif
-#if !defined(__APPLE__) || defined(__aarch64__)
-	if (sigaction(SIGSEGV, &sa, &s_old_sigsegv_action) != 0)
-	{
-		Error::SetErrno(error, "sigaction() for SIGBUS failed: ", errno);
-		return false;
-	}
-#endif
-#if defined(__APPLE__) && defined(__aarch64__)
-	// Stops LLDB getting in a EXC_BAD_ACCESS loop when passing page faults to PCSX2.
-	task_set_exception_ports(mach_task_self(), EXC_MASK_BAD_ACCESS, MACH_PORT_NULL, EXCEPTION_DEFAULT, 0);
-#endif
-
-	s_exception_handler_installed = true;
-	return true;
-}
-
-#ifndef __APPLE__
-
 static __ri uint LinuxProt(const PageProtectionMode& mode)
 {
 	u32 lnxmode = 0;
@@ -251,11 +52,6 @@ void* HostSys::Mmap(void* base, size_t size, const PageProtectionMode& mode)
 	if (base)
 		flags |= MAP_FIXED_NOREPLACE;
 
-#if defined(__APPLE__) && defined(_M_ARM64)
-	if (mode.CanExecute())
-		flags |= MAP_JIT;
-#endif
-
 	void* res = mmap(base, size, prot, flags, -1, 0);
 	if (res == MAP_FAILED)
 		return nullptr;
@@ -338,15 +134,6 @@ void HostSys::UnmapSharedMemory(void* baseaddr, size_t size)
 		pxFailRel("Failed to unmap shared memory");
 }
 
-#ifdef _M_ARM64
-
-void HostSys::FlushInstructionCache(void* address, u32 size)
-{
-	__builtin___clear_cache(reinterpret_cast<char*>(address), reinterpret_cast<char*>(address) + size);
-}
-
-#endif
-
 SharedMemoryMappingArea::SharedMemoryMappingArea(u8* base_ptr, size_t size, size_t num_pages)
 	: m_base_ptr(base_ptr)
 	, m_size(size)
@@ -400,6 +187,137 @@ bool SharedMemoryMappingArea::Unmap(void* map_base, size_t map_size)
 	return true;
 }
 
-#endif // __APPLE__
+namespace PageFaultHandler
+{
+	static std::recursive_mutex s_exception_handler_mutex;
+	static bool s_in_exception_handler = false;
+	static bool s_installed = false;
+} // namespace PageFaultHandler
+
+#ifdef _M_ARM64
+
+void HostSys::FlushInstructionCache(void* address, u32 size)
+{
+	__builtin___clear_cache(reinterpret_cast<char*>(address), reinterpret_cast<char*>(address) + size);
+}
+
+[[maybe_unused]] static bool IsStoreInstruction(const void* ptr)
+{
+	u32 bits;
+	std::memcpy(&bits, ptr, sizeof(bits));
+
+	// Based on vixl's disassembler Instruction::IsStore().
+	// if (Mask(LoadStoreAnyFMask) != LoadStoreAnyFixed)
+	if ((bits & 0x0a000000) != 0x08000000)
+		return false;
+
+	// if (Mask(LoadStorePairAnyFMask) == LoadStorePairAnyFixed)
+	if ((bits & 0x3a000000) == 0x28000000)
+	{
+		// return Mask(LoadStorePairLBit) == 0
+		return (bits & (1 << 22)) == 0;
+	}
+
+	switch (bits & 0xC4C00000)
+	{
+		case 0x00000000: // STRB_w
+		case 0x40000000: // STRH_w
+		case 0x80000000: // STR_w
+		case 0xC0000000: // STR_x
+		case 0x04000000: // STR_b
+		case 0x44000000: // STR_h
+		case 0x84000000: // STR_s
+		case 0xC4000000: // STR_d
+		case 0x04800000: // STR_q
+			return true;
+
+		default:
+			return false;
+	}
+}
+
+#endif // _M_ARM64
+
+namespace PageFaultHandler
+{
+	static void SignalHandler(int sig, siginfo_t* info, void* ctx);
+} // namespace PageFaultHandler
+
+void PageFaultHandler::SignalHandler(int sig, siginfo_t* info, void* ctx)
+{
+#if defined(__linux__)
+	void* const exception_address = reinterpret_cast<void*>(info->si_addr);
+
+#if defined(_M_X86)
+	void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_RIP]);
+	const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.gregs[REG_ERR] & 2) != 0;
+#elif defined(_M_ARM64)
+	void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.pc);
+	const bool is_write = IsStoreInstruction(exception_pc);
+#endif
+
+#elif defined(__FreeBSD__)
+
+#if defined(_M_X86)
+	void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_addr);
+	void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_rip);
+	const bool is_write = (static_cast<ucontext_t*>(ctx)->uc_mcontext.mc_err & 2) != 0;
+#elif defined(_M_ARM64)
+	void* const exception_address = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__es.__far);
+	void* const exception_pc = reinterpret_cast<void*>(static_cast<ucontext_t*>(ctx)->uc_mcontext->__ss.__pc);
+	const bool is_write = IsStoreInstruction(exception_pc);
+#endif
 
 #endif
+
+	// Executing the handler concurrently from multiple threads wouldn't go down well.
+	s_exception_handler_mutex.lock();
+
+	// Prevent recursive exception filtering.
+	HandlerResult result = HandlerResult::ExecuteNextHandler;
+	if (!s_in_exception_handler)
+	{
+		s_in_exception_handler = true;
+		result = HandlePageFault(exception_pc, exception_address, is_write);
+		s_in_exception_handler = false;
+	}
+
+	s_exception_handler_mutex.unlock();
+
+	// Resumes execution right where we left off (re-executes instruction that caused the SIGSEGV).
+	if (result == HandlerResult::ContinueExecution)
+		return;
+
+	// We couldn't handle it. Pass it off to the crash dumper.
+	CrashHandler::CrashSignalHandler(sig, info, ctx);
+}
+
+bool PageFaultHandler::Install(Error* error)
+{
+	std::unique_lock lock(s_exception_handler_mutex);
+	pxAssertRel(!s_installed, "Page fault handler has already been installed.");
+
+	struct sigaction sa;
+
+	sigemptyset(&sa.sa_mask);
+	sa.sa_flags = SA_SIGINFO | SA_NODEFER;
+	sa.sa_sigaction = SignalHandler;
+
+	if (sigaction(SIGSEGV, &sa, nullptr) != 0)
+	{
+		Error::SetErrno(error, "sigaction() for SIGSEGV failed: ", errno);
+		return false;
+	}
+
+#ifdef _M_ARM64
+	// We can get SIGBUS on ARM64.
+	if (sigaction(SIGBUS, &sa, nullptr) != 0)
+	{
+		Error::SetErrno(error, "sigaction() for SIGBUS failed: ", errno);
+		return false;
+	}
+#endif
+
+	s_installed = true;
+	return true;
+}

common/Linux/LnxMisc.cpp

@@ -1,8 +1,6 @@
-// SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
+// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if !defined(_WIN32) && !defined(__APPLE__)
-
 #include "common/Pcsx2Types.h"
 #include "common/Console.h"
 #include "common/HostSys.h"
@@ -215,5 +213,3 @@ void Threading::SleepUntil(u64 ticks)
 	ts.tv_nsec = static_cast<long>(ticks % 1000000000ULL);
 	clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &ts, nullptr);
 }
-
-#endif

common/Linux/LnxThreads.cpp

@@ -1,11 +1,13 @@
-// SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
+// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if !defined(_WIN32) && !defined(__APPLE__)
 #ifndef _GNU_SOURCE
 #define _GNU_SOURCE
 #endif
 
+#include "common/Threading.h"
+#include "common/Assertions.h"
+
 #include <memory>
 
 #include <pthread.h>
@@ -20,20 +22,10 @@
 #include <sys/syscall.h>
 #define gettid() syscall(SYS_gettid)
 #endif
-
+#else
-#elif defined(__unix__)
 #include <pthread_np.h>
 #endif
 
-#include "common/Threading.h"
-#include "common/Assertions.h"
-
-#if !defined(__unix__)
-
-#pragma message("LnxThreads.cpp should only be compiled by projects or makefiles targeted at Linux/BSD distros.")
-
-#else
-
 // Note: assuming multicore is safer because it forces the interlocked routines to use
 // the LOCK prefix.  The prefix works on single core CPUs fine (but is slow), but not
 // having the LOCK prefix is very bad indeed.
@@ -354,6 +346,3 @@ void Threading::SetNameOfCurrentThread(const char* name)
 	pthread_set_name_np(pthread_self(), name);
 #endif
 }
-
-#endif
-#endif

common/Semaphore.cpp

@@ -137,7 +137,7 @@ void Threading::WorkSema::Reset()
 	m_state = STATE_RUNNING_0;
 }
 
-#if !defined(__APPLE__) // macOS implementations are in DarwinSemaphore
+#if !defined(__APPLE__) // macOS implementations are in DarwinThreads
 
 Threading::KernelSemaphore::KernelSemaphore()
 {

common/Windows/WinHostSys.cpp

@@ -1,8 +1,6 @@
 // SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if defined(_WIN32)
-
 #include "common/HostSys.h"
 #include "common/AlignedMalloc.h"
 #include "common/Assertions.h"
@@ -17,57 +15,6 @@
 
 #include <mutex>
 
-static std::recursive_mutex s_exception_handler_mutex;
-static bool s_in_exception_handler = false;
-static bool s_exception_handler_installed = false;
-
-long __stdcall SysPageFaultExceptionFilter(EXCEPTION_POINTERS* eps)
-{
-	// Executing the handler concurrently from multiple threads wouldn't go down well.
-	std::unique_lock lock(s_exception_handler_mutex);
-
-	// Prevent recursive exception filtering.
-	if (s_in_exception_handler)
-		return EXCEPTION_CONTINUE_SEARCH;
-
-	// Only interested in page faults.
-	if (eps->ExceptionRecord->ExceptionCode != EXCEPTION_ACCESS_VIOLATION)
-		return EXCEPTION_CONTINUE_SEARCH;
-
-#if defined(_M_AMD64)
-	const uptr exception_pc = static_cast<uptr>(eps->ContextRecord->Rip);
-#elif defined(_M_ARM64)
-	const uptr exception_pc = static_cast<uptr>(eps->ContextRecord->Pc);
-#endif
-
-	const uptr exception_addr = static_cast<uptr>(eps->ExceptionRecord->ExceptionInformation[1]);
-	const bool is_write = (eps->ExceptionRecord->ExceptionInformation[0] == 1);
-
-	s_in_exception_handler = true;
-
-	const bool handled = PageFaultHandler::HandlePageFault(exception_pc, exception_addr, is_write);
-
-	s_in_exception_handler = false;
-	
-	return handled ? EXCEPTION_CONTINUE_EXECUTION : EXCEPTION_CONTINUE_SEARCH;
-}
-
-bool PageFaultHandler::Install(Error* error)
-{
-	std::unique_lock lock(s_exception_handler_mutex);
-	pxAssertRel(!s_exception_handler_installed, "Page fault handler has already been installed.");
-
-	PVOID handle = AddVectoredExceptionHandler(1, SysPageFaultExceptionFilter);
-	if (!handle)
-	{
-		Error::SetWin32(error, "AddVectoredExceptionHandler() failed: ", GetLastError());
-		return false;
-	}
-
-	s_exception_handler_installed = true;
-	return true;
-}
-
 static DWORD ConvertToWinApi(const PageProtectionMode& mode)
 {
 	DWORD winmode = PAGE_NOACCESS;
@@ -309,7 +256,7 @@ bool SharedMemoryMappingArea::Unmap(void* map_base, size_t map_size)
 
 		// combine placeholders before and the range we're unmapping, i.e. to the left
 		if (!VirtualFreeEx(GetCurrentProcess(), OffsetPointer(left_it->first),
-				 left_it->second - left_it->first, MEM_RELEASE | MEM_COALESCE_PLACEHOLDERS))
+				left_it->second - left_it->first, MEM_RELEASE | MEM_COALESCE_PLACEHOLDERS))
 		{
 			pxFail("Failed to coalesce placeholders left for unmap");
 		}
@@ -341,4 +288,60 @@ bool SharedMemoryMappingArea::Unmap(void* map_base, size_t map_size)
 	return true;
 }
 
+namespace PageFaultHandler
+{
+	static LONG ExceptionHandler(PEXCEPTION_POINTERS exi);
+
+	static std::recursive_mutex s_exception_handler_mutex;
+	static bool s_in_exception_handler = false;
+	static bool s_installed = false;
+} // namespace PageFaultHandler
+
+LONG PageFaultHandler::ExceptionHandler(PEXCEPTION_POINTERS exi)
+{
+	// Executing the handler concurrently from multiple threads wouldn't go down well.
+	std::unique_lock lock(s_exception_handler_mutex);
+
+	// Prevent recursive exception filtering.
+	if (s_in_exception_handler)
+		return EXCEPTION_CONTINUE_SEARCH;
+
+	// Only interested in page faults.
+	if (exi->ExceptionRecord->ExceptionCode != EXCEPTION_ACCESS_VIOLATION)
+		return EXCEPTION_CONTINUE_SEARCH;
+
+#if defined(_M_X86)
+	void* const exception_pc = reinterpret_cast<void*>(exi->ContextRecord->Rip);
+#elif defined(_M_ARM64)
+	void* const exception_pc = reinterpret_cast<void*>(exi->ContextRecord->Pc);
+#else
+	void* const exception_pc = nullptr;
 #endif
+
+	void* const exception_address = reinterpret_cast<void*>(exi->ExceptionRecord->ExceptionInformation[1]);
+	const bool is_write = exi->ExceptionRecord->ExceptionInformation[0] == 1;
+
+	s_in_exception_handler = true;
+
+	const HandlerResult handled = HandlePageFault(exception_pc, exception_address, is_write);
+
+	s_in_exception_handler = false;
+
+	return (handled == HandlerResult::ContinueExecution) ? EXCEPTION_CONTINUE_EXECUTION : EXCEPTION_CONTINUE_SEARCH;
+}
+
+bool PageFaultHandler::Install(Error* error)
+{
+	std::unique_lock lock(s_exception_handler_mutex);
+	pxAssertRel(!s_installed, "Page fault handler has already been installed.");
+
+	PVOID handle = AddVectoredExceptionHandler(1, ExceptionHandler);
+	if (!handle)
+	{
+		Error::SetWin32(error, "AddVectoredExceptionHandler() failed: ", GetLastError());
+		return false;
+	}
+
+	s_installed = true;
+	return true;
+}

common/Windows/WinMisc.cpp

@@ -1,8 +1,6 @@
-// SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
+// SPDX-FileCopyrightText: 2002-2024 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if defined(_WIN32)
-
 #include "common/FileSystem.h"
 #include "common/HostSys.h"
 #include "common/RedtapeWindows.h"
@@ -126,4 +124,3 @@ void Threading::SleepUntil(u64 ticks)
 	}
 }
 
-#endif

common/Windows/WinThreads.cpp

@@ -1,8 +1,6 @@
 // SPDX-FileCopyrightText: 2002-2023 PCSX2 Dev Team
 // SPDX-License-Identifier: LGPL-3.0+
 
-#if defined(_WIN32)
-
 #include "common/Threading.h"
 #include "common/Assertions.h"
 #include "common/RedtapeWindows.h"
@@ -265,5 +263,3 @@ void Threading::SetNameOfCurrentThread(const char* name)
 	}
 #endif
 }
-
-#endif

common/common.vcxproj

@@ -74,9 +74,6 @@
     <ClCompile Include="PrecompiledHeader.cpp">
       <PrecompiledHeader>Create</PrecompiledHeader>
     </ClCompile>
-    <ClCompile Include="Linux\LnxHostSys.cpp" />
-    <ClCompile Include="Linux\LnxMisc.cpp" />
-    <ClCompile Include="Linux\LnxThreads.cpp" />
     <ClCompile Include="Windows\WinHostSys.cpp" />
     <ClCompile Include="Windows\WinMisc.cpp" />
     <ClCompile Include="Windows\WinThreads.cpp" />

common/common.vcxproj.filters

@@ -28,15 +28,6 @@
     <ClCompile Include="emitter\avx.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="Linux\LnxHostSys.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
-    <ClCompile Include="Linux\LnxMisc.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
-    <ClCompile Include="Linux\LnxThreads.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="emitter\movs.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>

pcsx2/vtlb.cpp

@@ -1454,12 +1454,12 @@ static __fi void mmap_ClearCpuBlock(uint offset)
 	Cpu->Clear(m_PageProtectInfo[rampage].ReverseRamMap, __pagesize);
 }
 
-bool PageFaultHandler::HandlePageFault(uptr pc, uptr addr, bool is_write)
+PageFaultHandler::HandlerResult PageFaultHandler::HandlePageFault(void* exception_pc, void* fault_address, bool is_write)
 {
 	pxAssert(eeMem);
 
 	u32 vaddr;
-	if (CHECK_FASTMEM && vtlb_GetGuestAddress(addr, &vaddr))
+	if (CHECK_FASTMEM && vtlb_GetGuestAddress(reinterpret_cast<uptr>(fault_address), &vaddr))
 	{
 		// this was inside the fastmem area. check if it's a code page
 		// fprintf(stderr, "Fault on fastmem %p vaddr %08X\n", info.addr, vaddr);
@@ -1470,23 +1470,26 @@ bool PageFaultHandler::HandlePageFault(uptr pc, uptr addr, bool is_write)
 		{
 			// fprintf(stderr, "Not backpatching code write at %08X\n", vaddr);
 			mmap_ClearCpuBlock(offset);
-			return true;
+			return HandlerResult::ContinueExecution;
 		}
 		else
 		{
 			// fprintf(stderr, "Trying backpatching vaddr %08X\n", vaddr);
-			return vtlb_BackpatchLoadStore(pc, addr);
+			return vtlb_BackpatchLoadStore(reinterpret_cast<uptr>(exception_pc),
+					   reinterpret_cast<uptr>(fault_address)) ?
+					   HandlerResult::ContinueExecution :
+					   HandlerResult::ExecuteNextHandler;
 		}
 	}
 	else
 	{
 		// get bad virtual address
-		uptr offset = addr - (uptr)eeMem->Main;
+		uptr offset = reinterpret_cast<uptr>(fault_address) - reinterpret_cast<uptr>(eeMem->Main);
 		if (offset >= Ps2MemSize::ExposedRam)
-			return false;
+			return HandlerResult::ExecuteNextHandler;
 
 		mmap_ClearCpuBlock(offset);
-		return true;
+		return HandlerResult::ContinueExecution;
 	}
 }