Merge pull request #2605 from dolphin-emu/revert-2358-pie

Revert "x64: build a Position-Independent Executable (PIE)"

1 files changed, 101 insertions, 19 deletions

diff --git a/Source/Core/Common/MemoryUtil.cpp b/Source/Core/Common/MemoryUtil.cpp
index e4563e3409..510b258b09 100644
--- a/Source/Core/Common/MemoryUtil.cpp
+++ b/Source/Core/Common/MemoryUtil.cpp
@@ -27,29 +27,71 @@
 #endif
 #endif
 
-void* AllocateExecutableMemory(size_t size, void* map_hint)
+// Valgrind doesn't support MAP_32BIT.
+// Uncomment the following line to be able to run Dolphin in Valgrind.
+//#undef MAP_32BIT
+
+#if !defined(_WIN32) && defined(_M_X86_64) && !defined(MAP_32BIT)
+#include <unistd.h>
+#define PAGE_MASK     (getpagesize() - 1)
+#define round_page(x) ((((unsigned long)(x)) + PAGE_MASK) & ~(PAGE_MASK))
+#endif
+
+// This is purposely not a full wrapper for virtualalloc/mmap, but it
+// provides exactly the primitive operations that Dolphin needs.
+
+void* AllocateExecutableMemory(size_t size, bool low)
 {
 #if defined(_WIN32)
 	void* ptr = VirtualAlloc(0, size, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
 #else
+	static char *map_hint = nullptr;
+#if defined(_M_X86_64) && !defined(MAP_32BIT)
+	// This OS has no flag to enforce allocation below the 4 GB boundary,
+	// but if we hint that we want a low address it is very likely we will
+	// get one.
+	// An older version of this code used MAP_FIXED, but that has the side
+	// effect of discarding already mapped pages that happen to be in the
+	// requested virtual memory range (such as the emulated RAM, sometimes).
+	if (low && (!map_hint))
+		map_hint = (char*)round_page(512*1024*1024); /* 0.5 GB rounded up to the next page */
+#endif
 	void* ptr = mmap(map_hint, size, PROT_READ | PROT_WRITE | PROT_EXEC,
-	                 MAP_ANON | MAP_PRIVATE, -1, 0);
+		MAP_ANON | MAP_PRIVATE
+#if defined(_M_X86_64) && defined(MAP_32BIT)
+		| (low ? MAP_32BIT : 0)
+#endif
+		, -1, 0);
 #endif /* defined(_WIN32) */
 
+	// printf("Mapped executable memory at %p (size %ld)\n", ptr,
+	//	(unsigned long)size);
+
 #ifdef _WIN32
 	if (ptr == nullptr)
+	{
 #else
 	if (ptr == MAP_FAILED)
-#endif
 	{
 		ptr = nullptr;
-		PanicAlert("Failed to allocate executable memory.");
+#endif
+		PanicAlert("Failed to allocate executable memory. If you are running Dolphin in Valgrind, try '#undef MAP_32BIT'.");
+	}
+#if !defined(_WIN32) && defined(_M_X86_64) && !defined(MAP_32BIT)
+	else
+	{
+		if (low)
+		{
+			map_hint += size;
+			map_hint = (char*)round_page(map_hint); /* round up to the next page */
+			// printf("Next map will (hopefully) be at %p\n", map_hint);
+		}
 	}
+#endif
 
-#ifdef _X86_64
-	ptrdiff_t ofs = (u8*)ptr - (u8*)map_hint;
-	if (ofs < -0x80000000ll || ofs + size > 0x80000000ll)
-		PanicAlert("Executable range can't be used for RIP-relative addressing.");
+#if _M_X86_64
+	if ((u64)ptr >= 0x80000000 && low == true)
+		PanicAlert("Executable memory ended up above 2GB!");
 #endif
 
 	return ptr;
@@ -75,12 +117,18 @@ void* AllocateMemoryPages(size_t size)
 
 void* AllocateAlignedMemory(size_t size, size_t alignment)
 {
-	void* ptr = nullptr;
 #ifdef _WIN32
-	if (!(ptr = _aligned_malloc(size, alignment)))
+	void* ptr = _aligned_malloc(size, alignment);
 #else
-	if (posix_memalign(&ptr, alignment, size))
+	void* ptr = nullptr;
+	if (posix_memalign(&ptr, alignment, size) != 0)
+		ERROR_LOG(MEMMAP, "Failed to allocate aligned memory");
 #endif
+
+	// printf("Mapped memory at %p (size %ld)\n", ptr,
+	//	(unsigned long)size);
+
+	if (ptr == nullptr)
 		PanicAlert("Failed to allocate aligned memory");
 
 	return ptr;
@@ -88,12 +136,23 @@ void* AllocateAlignedMemory(size_t size, size_t alignment)
 
 void FreeMemoryPages(void* ptr, size_t size)
 {
+	if (ptr)
+	{
+		bool error_occurred = false;
+
 #ifdef _WIN32
-	if (ptr && !VirtualFree(ptr, 0, MEM_RELEASE))
+		if (!VirtualFree(ptr, 0, MEM_RELEASE))
+			error_occurred = true;
 #else
-	if (ptr && munmap(ptr, size))
+		int retval = munmap(ptr, size);
+
+		if (retval != 0)
+			error_occurred = true;
 #endif
-		PanicAlert("FreeMemoryPages failed!\n%s", GetLastErrorMsg().c_str());
+
+		if (error_occurred)
+			PanicAlert("FreeMemoryPages failed!\n%s", GetLastErrorMsg().c_str());
+	}
 }
 
 void FreeAlignedMemory(void* ptr)
@@ -110,34 +169,58 @@ void FreeAlignedMemory(void* ptr)
 
 void ReadProtectMemory(void* ptr, size_t size)
 {
+	bool error_occurred = false;
+
 #ifdef _WIN32
 	DWORD oldValue;
 	if (!VirtualProtect(ptr, size, PAGE_NOACCESS, &oldValue))
+		error_occurred = true;
 #else
-	if (mprotect(ptr, size, PROT_NONE))
+	int retval = mprotect(ptr, size, PROT_NONE);
+
+	if (retval != 0)
+		error_occurred = true;
 #endif
+
+	if (error_occurred)
 		PanicAlert("ReadProtectMemory failed!\n%s", GetLastErrorMsg().c_str());
 }
 
 void WriteProtectMemory(void* ptr, size_t size, bool allowExecute)
 {
+	bool error_occurred = false;
+
 #ifdef _WIN32
 	DWORD oldValue;
 	if (!VirtualProtect(ptr, size, allowExecute ? PAGE_EXECUTE_READ : PAGE_READONLY, &oldValue))
+		error_occurred = true;
 #else
-	if (mprotect(ptr, size, PROT_READ | (allowExecute ? PROT_EXEC : 0)))
+	int retval = mprotect(ptr, size, allowExecute ? (PROT_READ | PROT_EXEC) : PROT_READ);
+
+	if (retval != 0)
+		error_occurred = true;
 #endif
+
+	if (error_occurred)
 		PanicAlert("WriteProtectMemory failed!\n%s", GetLastErrorMsg().c_str());
 }
 
 void UnWriteProtectMemory(void* ptr, size_t size, bool allowExecute)
 {
+	bool error_occurred = false;
+
 #ifdef _WIN32
 	DWORD oldValue;
 	if (!VirtualProtect(ptr, size, allowExecute ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE, &oldValue))
+		error_occurred = true;
 #else
-	if (mprotect(ptr, size, PROT_READ | PROT_WRITE | (allowExecute ? PROT_EXEC : 0)))
+	int retval = mprotect(ptr, size, allowExecute ? (PROT_READ | PROT_WRITE | PROT_EXEC) : PROT_WRITE | PROT_READ);
+
+	if (retval != 0)
+		error_occurred = true;
 #endif
+
+	if (error_occurred)
 		PanicAlert("UnWriteProtectMemory failed!\n%s", GetLastErrorMsg().c_str());
 }
 
@@ -153,8 +236,7 @@ std::string MemUsage()
 	// Print information about the memory usage of the process.
 
 	hProcess = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, processID);
-	if (nullptr == hProcess)
-		return "MemUsage Error";
+	if (nullptr == hProcess) return "MemUsage Error";
 
 	if (GetProcessMemoryInfo(hProcess, &pmc, sizeof(pmc)))
 		Ret = StringFromFormat("%s K", ThousandSeparate(pmc.WorkingSetSize / 1024, 7).c_str());