backend/A64: Fix SpinLockImpl not setting required memory permissions. (#9)

src/dynarmic/backend/A64/block_of_code.cpp

@@ -17,16 +17,6 @@
 #include "dynarmic/backend/A64/perf_map.h"
 #include "dynarmic/interface/halt_reason.h"
 
-#ifdef _WIN32
-#    include <windows.h>
-#else
-#    include <sys/mman.h>
-#endif
-
-#ifdef __APPLE__
-#    include <pthread.h>
-#endif
-
 namespace Dynarmic::BackendA64 {
 
 const Arm64Gen::ARM64Reg BlockOfCode::ABI_RETURN = Arm64Gen::ARM64Reg::X0;
@@ -53,23 +43,6 @@ namespace {
 constexpr size_t TOTAL_CODE_SIZE = 128 * 1024 * 1024;
 constexpr size_t FAR_CODE_OFFSET = 100 * 1024 * 1024;
 
-#ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
-void ProtectMemory([[maybe_unused]] const void* base, [[maybe_unused]] size_t size, bool is_executable) {
-#    if defined(_WIN32)
-    DWORD oldProtect = 0;
-    VirtualProtect(const_cast<void*>(base), size, is_executable ? PAGE_EXECUTE_READ : PAGE_READWRITE, &oldProtect);
-#    elif defined(__APPLE__)
-    pthread_jit_write_protect_np(is_executable);
-#    else
-    static const size_t pageSize = sysconf(_SC_PAGESIZE);
-    const size_t iaddr = reinterpret_cast<size_t>(base);
-    const size_t roundAddr = iaddr & ~(pageSize - static_cast<size_t>(1));
-    const int mode = is_executable ? (PROT_READ | PROT_EXEC) : (PROT_READ | PROT_WRITE);
-    mprotect(reinterpret_cast<void*>(roundAddr), size + (iaddr - roundAddr), mode);
-#    endif
-}
-#endif
-
 }  // anonymous namespace
 
 BlockOfCode::BlockOfCode(RunCodeCallbacks cb, JitStateInfo jsi)
@@ -91,18 +64,6 @@ void BlockOfCode::PreludeComplete() {
     DisableWriting();
 }
 
-void BlockOfCode::EnableWriting() {
-#ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
-    ProtectMemory(GetCodePtr(), TOTAL_CODE_SIZE, false);
-#endif
-}
-
-void BlockOfCode::DisableWriting() {
-#ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
-    ProtectMemory(GetCodePtr(), TOTAL_CODE_SIZE, true);
-#endif
-}
-
 void BlockOfCode::ClearCache() {
     ASSERT(prelude_complete);
     in_far_code = false;

src/dynarmic/backend/A64/block_of_code.h

@@ -38,11 +38,6 @@ public:
     /// Call when external emitters have finished emitting their preludes.
     void PreludeComplete();
 
-    /// Change permissions to RW. This is required to support systems with W^X enforced.
-    void EnableWriting();
-    /// Change permissions to RX. This is required to support systems with W^X enforced.
-    void DisableWriting();
-
     /// Clears this block of code and resets code pointer to beginning.
     void ClearCache();
     /// Calculates how much space is remaining to use. This is the minimum of near code and far code.

src/dynarmic/backend/A64/emitter/code_block.h

@@ -13,6 +13,10 @@
 #    include <sys/mman.h>
 #endif
 
+#ifdef __APPLE__
+#    include <pthread.h>
+#endif
+
 #include <mcl/assert.hpp>
 #include <mcl/stdint.hpp>
 
@@ -29,6 +33,23 @@ private:
     // host specific breakpoint instruction
     virtual void PoisonMemory() = 0;
 
+#ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
+    void ProtectMemory([[maybe_unused]] const void* base, [[maybe_unused]] size_t size, bool is_executable) {
+#    if defined(_WIN32)
+        DWORD oldProtect = 0;
+        VirtualProtect(const_cast<void*>(base), size, is_executable ? PAGE_EXECUTE_READ : PAGE_READWRITE, &oldProtect);
+#    elif defined(__APPLE__)
+        pthread_jit_write_protect_np(is_executable);
+#    else
+        static const size_t pageSize = sysconf(_SC_PAGESIZE);
+        const size_t iaddr = reinterpret_cast<size_t>(base);
+        const size_t roundAddr = iaddr & ~(pageSize - static_cast<size_t>(1));
+        const int mode = is_executable ? (PROT_READ | PROT_EXEC) : (PROT_READ | PROT_WRITE);
+        mprotect(reinterpret_cast<void*>(roundAddr), size + (iaddr - roundAddr), mode);
+#    endif
+    }
+#endif
+
 protected:
     u8* region = nullptr;
     // Size of region we can use.
@@ -136,5 +157,19 @@ public:
         child->ResetCodePtr();
         m_children.emplace_back(child);
     }
+
+    /// Change permissions to RW. This is required to support systems with W^X enforced.
+    void EnableWriting() {
+#ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
+        ProtectMemory(T::GetCodePtr(), total_region_size, false);
+#endif
+    }
+
+    /// Change permissions to RX. This is required to support systems with W^X enforced.
+    void DisableWriting() {
+#ifdef DYNARMIC_ENABLE_NO_EXECUTE_SUPPORT
+        ProtectMemory(T::GetCodePtr(), total_region_size, true);
+#endif
+    }
 };
 }  // namespace Dynarmic::BackendA64

src/dynarmic/backend/A64/spin_lock_arm64.cpp

@@ -51,6 +51,7 @@ SpinLockImpl impl;
 
 SpinLockImpl::SpinLockImpl() {
     code.AllocCodeSpace(64);
+    code.EnableWriting();
     const ARM64Reg ABI_PARAM1 = BackendA64::HostLocToReg64(BackendA64::ABI_PARAM1);
     code.AlignCode16();
     lock = reinterpret_cast<void (*)(volatile int*)>(code.GetWritableCodePtr());
@@ -61,6 +62,7 @@ SpinLockImpl::SpinLockImpl() {
     unlock = reinterpret_cast<void (*)(volatile int*)>(code.GetWritableCodePtr());
     EmitSpinLockUnlock(code, ABI_PARAM1);
     code.RET();
+    code.DisableWriting();
     code.FlushIcache();
 }