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Apple M1: MacOS 11.2 mprotect restrictions

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In MacOS 11.2 mprotect can no longer change the access protection settings of
pages that were previously marked as executable to anything but PROT_NONE. This
commit works around this new restriction by bypassing the mprotect based write
protection and instead relying on the write protection provided by MAP_JIT.
This commit is contained in:
Skyler Saleh 2021-02-03 07:11:30 -08:00
parent 8cb86e7ae0
commit 4ff429266a
1 changed files with 11 additions and 3 deletions
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14
Source/Core/Common/MemoryUtil.cpp
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@ -41,7 +41,9 @@ void* AllocateExecutableMemory(size_t size)
#else
int map_flags = MAP_ANON | MAP_PRIVATE;
#if defined(_M_ARM_64) && defined(__APPLE__)
// This check is in place to prepare for x86_64 MAP_JIT support.
// This check is in place to prepare for x86_64 MAP_JIT support. While MAP_JIT did exist
// prior to 10.14, it had restrictions on the number of JIT allocations that were removed
// in 10.14.
if (__builtin_available(macOS 10.14, *))
map_flags |= MAP_JIT;
#endif
@ -206,7 +208,10 @@ void WriteProtectMemory(void* ptr, size_t size, bool allowExecute)
DWORD oldValue;
if (!VirtualProtect(ptr, size, allowExecute ? PAGE_EXECUTE_READ : PAGE_READONLY, &oldValue))
PanicAlertFmt("WriteProtectMemory failed!\nVirtualProtect: {}", GetLastErrorString());
#else
#elif !(defined(_M_ARM_64) && defined(__APPLE__))
// MacOS 11.2 on ARM does not allow for changing the access permissions of pages
// that were marked executable, instead it uses the protections offered by MAP_JIT
// for write protection.
if (mprotect(ptr, size, allowExecute ? (PROT_READ | PROT_EXEC) : PROT_READ) != 0)
PanicAlertFmt("WriteProtectMemory failed!\nmprotect: {}", LastStrerrorString());
#endif
@ -218,7 +223,10 @@ void UnWriteProtectMemory(void* ptr, size_t size, bool allowExecute)
DWORD oldValue;
if (!VirtualProtect(ptr, size, allowExecute ? PAGE_EXECUTE_READWRITE : PAGE_READWRITE, &oldValue))
PanicAlertFmt("UnWriteProtectMemory failed!\nVirtualProtect: {}", GetLastErrorString());
#else
#elif !(defined(_M_ARM_64) && defined(__APPLE__))
// MacOS 11.2 on ARM does not allow for changing the access permissions of pages
// that were marked executable, instead it uses the protections offered by MAP_JIT
// for write protection.
if (mprotect(ptr, size,
allowExecute ? (PROT_READ | PROT_WRITE | PROT_EXEC) : PROT_WRITE | PROT_READ) != 0)
{