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Revert "Fix race condition in memory_decommit/memory_reset on Apple ARM64"

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This reverts commit 4cac76caad.
This commit is contained in:
schm1dtmac 2026-04-29 17:41:02 +01:00 • committed by kd-11
parent 3c9a4417f2
commit f3cf1da7b7
1 changed files with 8 additions and 8 deletions
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16
rpcs3/util/vm_native.cpp
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@ -347,11 +347,12 @@ namespace utils
#else
const u64 ptr64 = reinterpret_cast<u64>(pointer);
#if defined(__APPLE__) && defined(ARCH_ARM64)
// Use MAP_FIXED without MAP_JIT to atomically replace the mapping.
// Apple rejects MAP_FIXED | MAP_JIT, but MAP_FIXED alone works and
// avoids the race condition of the previous munmap+mmap approach
// where another thread could claim the address range between the two calls.
ensure(::mmap(pointer, size, PROT_NONE, MAP_FIXED | MAP_ANON | MAP_PRIVATE | c_map_noreserve, -1, 0) != reinterpret_cast<void*>(uptr{umax}));
// Hack: on macOS, Apple explicitly fails mmap if you combine MAP_FIXED and MAP_JIT.
// So we unmap the space and just hope it maps to the same address we got before instead.
// The Xcode manpage says the pointer is a hint and the OS will try to map at the hint location
// so this isn't completely undefined behavior.
ensure(::munmap(pointer, size) != -1);
ensure(::mmap(pointer, size, PROT_NONE, MAP_ANON | MAP_PRIVATE | MAP_JIT, -1, 0) == pointer);
#else
ensure(::mmap(pointer, size, PROT_NONE, MAP_FIXED | MAP_ANON | MAP_PRIVATE | c_map_noreserve, -1, 0) != reinterpret_cast<void*>(uptr{umax}));
#endif
@ -380,9 +381,8 @@ namespace utils
#else
const u64 ptr64 = reinterpret_cast<u64>(pointer);
#if defined(__APPLE__) && defined(ARCH_ARM64)
// Use MAP_FIXED without MAP_JIT to atomically replace the mapping.
// See memory_decommit for details on why the munmap+mmap approach is unsafe.
ensure(::mmap(pointer, size, +prot, MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0) != reinterpret_cast<void*>(uptr{umax}));
ensure(::munmap(pointer, size) != -1);
ensure(::mmap(pointer, size, +prot, MAP_ANON | MAP_PRIVATE | MAP_JIT, -1, 0) == pointer);
#else
ensure(::mmap(pointer, size, +prot, MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0) != reinterpret_cast<void*>(uptr{umax}));
#endif