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Common: Don't use MAP_FIXED on Linux #11282

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merged 1 commit into from
May 21, 2024
Merged

Common: Don't use MAP_FIXED on Linux #11282

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5 changes: 3 additions & 2 deletions common/Linux/LnxHostSys.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -316,7 +316,7 @@ void* HostSys::MapSharedMemory(void* handle, size_t offset, void* baseaddr, size
{
const uint lnxmode = LinuxProt(mode);

const int flags = (baseaddr != nullptr) ? (MAP_SHARED | MAP_FIXED) : MAP_SHARED;
const int flags = (baseaddr != nullptr) ? (MAP_SHARED | MAP_FIXED_NOREPLACE) : MAP_SHARED;
void* ptr = mmap(baseaddr, size, lnxmode, flags, static_cast<int>(reinterpret_cast<intptr_t>(handle)), static_cast<off_t>(offset));
if (ptr == MAP_FAILED)
return nullptr;
Expand All @@ -326,7 +326,7 @@ void* HostSys::MapSharedMemory(void* handle, size_t offset, void* baseaddr, size

void HostSys::UnmapSharedMemory(void* baseaddr, size_t size)
{
if (mmap(baseaddr, size, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0) == MAP_FAILED)
if (munmap(baseaddr, size) != 0)
pxFailRel("Failed to unmap shared memory");
}

Expand Down Expand Up @@ -370,6 +370,7 @@ u8* SharedMemoryMappingArea::Map(void* file_handle, size_t file_offset, void* ma
{
pxAssert(static_cast<u8*>(map_base) >= m_base_ptr && static_cast<u8*>(map_base) < (m_base_ptr + m_size));

// MAP_FIXED is okay here, since we've reserved the entire region, and *want* to overwrite the mapping.
const uint lnxmode = LinuxProt(mode);
void* const ptr = mmap(map_base, map_size, lnxmode, MAP_SHARED | MAP_FIXED,
static_cast<int>(reinterpret_cast<intptr_t>(file_handle)), static_cast<off_t>(file_offset));
Expand Down
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