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JitCodeBuffer: Use MAP_FIXED on MacOS/MAP_FIXED_NOREPLACE on Linux

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Stenzek 2023-12-19 21:46:39 +10:00
parent 6a7dea6908
commit 05b42f34eb
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1 changed files with 21 additions and 1 deletions
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22
src/util/jit_code_buffer.cpp
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@ -111,9 +111,22 @@ bool JitCodeBuffer::TryAllocateAt(const void* addr)
return true;
#elif defined(__linux__) || defined(__ANDROID__) || defined(__APPLE__) || defined(__HAIKU__) || defined(__FreeBSD__)
int flags = MAP_PRIVATE | MAP_ANONYMOUS;
#if defined(__APPLE__) && defined(__aarch64__)
#if defined(__linux__)
// Linux does the right thing, allows us to not disturb an existing mapping.
if (addr)
flags |= MAP_FIXED_NOREPLACE;
#elif defined(__FreeBSD__)
// FreeBSD achieves the same with MAP_FIXED and MAP_EXCL.
if (addr)
flags |= MAP_FIXED | MAP_EXCL;
#elif defined(__APPLE__) && defined(__aarch64__)
// MAP_JIT and toggleable write protection is required on Apple Silicon.
flags |= MAP_JIT;
#elif defined(__APPLE__)
// MAP_FIXED is needed on x86 apparently.. hopefully there's nothing mapped at this address, otherwise we'll end up
// clobbering it..
if (addr)
flags |= MAP_FIXED;
#endif
m_code_ptr =
@ -125,6 +138,13 @@ bool JitCodeBuffer::TryAllocateAt(const void* addr)
return false;
}
else if (addr && m_code_ptr != addr)
{
if (munmap(m_code_ptr, m_total_size) != 0)
Log_ErrorPrintf("Failed to munmap() incorrectly hinted allocation: %d", errno);
m_code_ptr = nullptr;
return false;
}
return true;
#else