dolphin/Source/UnitTests/Core/PageFaultTest.cpp

// Copyright 2014 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#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> // NOLINT

#if _M_X86_64
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