Add a test for page fault handling.

This both tests that they work correctly and prints timing information
if you run it manually.

Source/UnitTests/Core/CMakeLists.txt

@@ -1 +1,2 @@
 add_dolphin_test(MMIOTest MMIOTest.cpp)
+add_dolphin_test(PageFaultTest PageFaultTest.cpp)

Source/UnitTests/Core/PageFaultTest.cpp

@@ -0,0 +1,77 @@
+#include <chrono>
+
+#include "Common/CommonTypes.h"
+#include "Common/Timer.h"
+#include "Core/MemTools.h"
+#include "Core/PowerPC/JitCommon/JitBase.h"
+
+// include order is important
+#include <gtest/gtest.h>
+
+#if _M_X86_64 || _M_ARM_32
+enum
+{
+#ifdef _WIN32
+	PAGE_GRAN = 0x10000
+#else
+	PAGE_GRAN = 0x1000
+#endif
+};
+
+class PageFaultFakeJit : public JitBase
+{
+public:
+	// CPUCoreBase methods
+	void Init() override {}
+	void Shutdown() override {}
+	void ClearCache() override {}
+	void Run() override {}
+	void SingleStep() override {}
+	const char *GetName() override { return nullptr; }
+
+	// JitBase methods
+	JitBaseBlockCache *GetBlockCache() override { return nullptr; }
+	void Jit(u32 em_address) override {}
+	const CommonAsmRoutinesBase *GetAsmRoutines() override { return nullptr; }
+
+	virtual bool HandleFault(uintptr_t access_address, SContext* ctx) override
+	{
+		m_pre_unprotect_time = std::chrono::high_resolution_clock::now();
+		UnWriteProtectMemory(m_data, PAGE_GRAN, /*allowExecute*/ false);
+		m_post_unprotect_time = std::chrono::high_resolution_clock::now();
+		return true;
+	}
+
+	void* m_data;
+	std::chrono::time_point<std::chrono::high_resolution_clock>
+		m_pre_unprotect_time, m_post_unprotect_time;
+};
+
+
+TEST(PageFault, PageFault)
+{
+	EMM::InstallExceptionHandler();
+	void* data = AllocateMemoryPages(PAGE_GRAN);
+	EXPECT_NE(data, nullptr);
+	WriteProtectMemory(data, PAGE_GRAN, false);
+
+	PageFaultFakeJit pfjit;
+	jit = &pfjit;
+	pfjit.m_data = data;
+
+	auto start = std::chrono::high_resolution_clock::now();
+	*(volatile int*) data = 5;
+	auto end = std::chrono::high_resolution_clock::now();
+
+	#define AS_NS(diff) ((unsigned long long)std::chrono::duration_cast<std::chrono::nanoseconds>(diff).count())
+
+	EMM::UninstallExceptionHandler();
+	jit = nullptr;
+
+	printf("page fault timing:\n");
+	printf("start->HandleFault     %llu ns\n", AS_NS(pfjit.m_pre_unprotect_time - start));
+	printf("UnWriteProtectMemory   %llu ns\n", AS_NS(pfjit.m_post_unprotect_time - pfjit.m_pre_unprotect_time));
+	printf("HandleFault->end       %llu ns\n", AS_NS(end - pfjit.m_post_unprotect_time));
+	printf("total                  %llu ns\n", AS_NS(end - start));
+}
+#endif