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Merge pull request #5778 from lioncash/buf

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SharedCodeBufferManager: Minor header tidying
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Ryan Houdek authored and GitHub committed 2026-07-21 09:18:25 -07:00
2 parents a652a5811b 10a0fe2e71
commit f2e35f336f
3 files changed
+28 -22
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FEXCore/Source/Interface/Core/SharedCodeBufferManager.cpp
+18 -20
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@@ -4,10 +4,11 @@
#include <FEXCore/fextl/memory.h>
#include <FEXCore/Utils/AllocatorHooks.h>
#include <FEXCore/Utils/LogManager.h>
#include <FEXCore/Utils/MathUtils.h>
#ifndef _WIN32
#include <sys/prctl.h>
#include <FEXCore/Utils/PrctlUtils.h>
#endif
namespace FEXCore::CPU {
@@ -39,26 +40,23 @@ CodeBuffer::~CodeBuffer() {
FEXCore::Allocator::VirtualFree(Ptr, AllocatedSize);
}
auto SharedCodeBufferManager::AllocateNew(size_t Size) -> fextl::shared_ptr<CodeBuffer> {
fextl::shared_ptr<CodeBuffer> SharedCodeBufferManager::AllocateNew(size_t Size) {
#ifndef _WIN32
// MDWE (Memory-Deny-Write-Execute) is a new Linux 6.3 feature.
// It's equivalent to systemd's `MemoryDenyWriteExecute` but implemented entirely in the kernel.
//
// MDWE prevents applications from creating RWX memory mappings.
// This prevents FEX from doing anything JIT related, as FEX uses RWX for JIT memory mappings.
//
// A potential workaround to make FEX work with MDWE is to call mprotect every time we need to write or modify code.
// Alternatively, FEX could use a memory mirror where one half is mapped as RW and the other is RX.
//
// Once MDWE is enabled with the prctl, the feature is sealed and it can /NOT/ be turned off.
//
// Status of MDWE is queried through prctl using `PR_GET_MDWE`:
// -1: The kernel doesn't support MDWE
// 0: MDWE is supported but disabled
// >0: MDWE is enabled, hence prohibiting RWX mappings
#ifndef PR_GET_MDWE
#define PR_GET_MDWE 66
#endif
// MDWE (Memory-Deny-Write-Execute) is a new Linux 6.3 feature.
// It's equivalent to systemd's `MemoryDenyWriteExecute` but implemented entirely in the kernel.
//
// MDWE prevents applications from creating RWX memory mappings.
// This prevents FEX from doing anything JIT related, as FEX uses RWX for JIT memory mappings.
//
// A potential workaround to make FEX work with MDWE is to call mprotect every time we need to write or modify code.
// Alternatively, FEX could use a memory mirror where one half is mapped as RW and the other is RX.
//
// Once MDWE is enabled with the prctl, the feature is sealed and it can /NOT/ be turned off.
//
// Status of MDWE is queried through prctl using `PR_GET_MDWE`:
// -1: The kernel doesn't support MDWE
// 0: MDWE is supported but disabled
// >0: MDWE is enabled, hence prohibiting RWX mappings
int MDWE = ::prctl(PR_GET_MDWE, 0, 0, 0, 0);
if (MDWE != -1 && MDWE != 0) {
LogMan::Msg::EFmt("MDWE was set to 0x{:x} which means FEX can't allocate executable memory", MDWE);
FEXCore/Source/Interface/Core/SharedCodeBufferManager.h
+5
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@@ -6,8 +6,13 @@ tags: backend|shared
$end_info$
*/
#pragma once
#include <FEXCore/fextl/memory.h>
#include <FEXCore/Utils/SignalScopeGuards.h>
#include <FEXCore/Utils/TypeDefines.h>
#include <cstddef>
#include <cstdint>
namespace FEXCore {
struct GuestToHostMap;
FEXCore/include/FEXCore/Utils/PrctlUtils.h
+5 -2
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@@ -2,8 +2,7 @@
#pragma once
#ifndef _WIN32
#include <sys/mman.h>
#include <sys/user.h>
#include <sys/prctl.h>
#ifndef PR_SET_VMA
@@ -50,4 +49,8 @@
#define PR_SHADOW_STACK_ENABLE (1ULL << 0)
#endif
#ifndef PR_GET_MDWE
#define PR_GET_MDWE 66
#endif
#endif // ifndef _WIN32