[NativeAOT/Apple] Map the thunks using vm_allocate/vm_map to avoid ne…

…ed for specific executable segment layout (dotnet#95914)

src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.Unix.targets

@@ -126,10 +126,6 @@ The .NET Foundation licenses this file to you under the MIT license.
       <NativeSystemLibrary Include="m" />
     </ItemGroup>
 
-    <ItemGroup>
-      <ExtraLinkerArg Include="-segprot,__THUNKS,rx,rx" Condition="'$(_IsApplePlatform)' == 'true'" />
-    </ItemGroup>
-
     <ItemGroup>
       <LinkerArg Include="-gz=zlib" Condition="'$(CompressSymbols)' != 'false'" />
       <LinkerArg Include="-fuse-ld=$(LinkerFlavor)" Condition="'$(LinkerFlavor)' != ''" />

src/coreclr/nativeaot/Runtime/PalRedhawk.h

@@ -686,7 +686,7 @@ REDHAWK_PALIMPORT void REDHAWK_PALAPI PalHijack(HANDLE hThread, _In_opt_ void* p
 REDHAWK_PALIMPORT UInt32_BOOL REDHAWK_PALAPI PalRegisterHijackCallback(_In_ PalHijackCallback callback);
 
 REDHAWK_PALIMPORT UInt32_BOOL REDHAWK_PALAPI PalAllocateThunksFromTemplate(_In_ HANDLE hTemplateModule, uint32_t templateRva, size_t templateSize, _Outptr_result_bytebuffer_(templateSize) void** newThunksOut);
-REDHAWK_PALIMPORT UInt32_BOOL REDHAWK_PALAPI PalFreeThunksFromTemplate(_In_ void *pBaseAddress);
+REDHAWK_PALIMPORT UInt32_BOOL REDHAWK_PALAPI PalFreeThunksFromTemplate(_In_ void *pBaseAddress, size_t templateSize);
 
 REDHAWK_PALIMPORT UInt32_BOOL REDHAWK_PALAPI PalMarkThunksAsValidCallTargets(
     void *virtualAddress,

src/coreclr/nativeaot/Runtime/ThunksMapping.cpp

@@ -329,6 +329,7 @@ EXTERN_C NATIVEAOT_API void* __cdecl RhAllocateThunksMapping()
     int thunkBlockSize = RhpGetThunkBlockSize();
     int templateSize = thunkBlocksPerMapping * thunkBlockSize;
 
+#ifndef TARGET_APPLE // Apple platforms cannot use the initial template
     if (pThunksTemplateAddress == NULL)
     {
         // First, we use the thunks directly from the thunks template sections in the module until all
@@ -337,12 +338,13 @@ EXTERN_C NATIVEAOT_API void* __cdecl RhAllocateThunksMapping()
         pThunkMap = pThunksTemplateAddress;
     }
     else
+#endif
     {
         // We've already used the thunks template in the module for some previous thunks, and we
         // cannot reuse it here. Now we need to create a new mapping of the thunks section in order to have
         // more thunks
 
-        uint8_t* pModuleBase = (uint8_t*)PalGetModuleHandleFromPointer(pThunksTemplateAddress);
+        uint8_t* pModuleBase = (uint8_t*)PalGetModuleHandleFromPointer(RhpGetThunksBase());
         int templateRva = (int)((uint8_t*)RhpGetThunksBase() - pModuleBase);
 
         if (!PalAllocateThunksFromTemplate((HANDLE)pModuleBase, templateRva, templateSize, &pThunkMap))
@@ -357,7 +359,7 @@ EXTERN_C NATIVEAOT_API void* __cdecl RhAllocateThunksMapping()
         thunkBlocksPerMapping))
     {
         if (pThunkMap != pThunksTemplateAddress)
-            PalFreeThunksFromTemplate(pThunkMap);
+            PalFreeThunksFromTemplate(pThunkMap, templateSize);
 
         return NULL;
     }

src/coreclr/nativeaot/Runtime/amd64/ThunkPoolThunks.S

@@ -38,22 +38,15 @@
 .endm
 
 #ifdef TARGET_APPLE
-    // Create two segments in the Mach-O file:
-    // __THUNKS with executable permissions
-    // __THUNKS_DATA with read/write permissions
-
-    .section __THUNKS,__thunks,regular,pure_instructions
+// Thunk pool
+    .text
     .p2align PAGE_SIZE_LOG2
 PATCH_LABEL ThunkPool
     .rept (THUNKS_MAP_SIZE / PAGE_SIZE)
     .p2align PAGE_SIZE_LOG2
     THUNKS_PAGE_BLOCK
     .endr
     .p2align PAGE_SIZE_LOG2
-    .section __THUNKS_DATA,__thunks,regular
-    .p2align PAGE_SIZE_LOG2
-    .space THUNKS_MAP_SIZE
-    .p2align PAGE_SIZE_LOG2
 #else
 #error Unsupported OS
 #endif

src/coreclr/nativeaot/Runtime/arm64/ThunkPoolThunks.S

@@ -46,22 +46,15 @@
 .endm
 
 #ifdef TARGET_APPLE
-    // Create two segments in the Mach-O file:
-    // __THUNKS with executable permissions
-    // __THUNKS_DATA with read/write permissions
-
-    .section __THUNKS,__thunks,regular,pure_instructions
+// Thunk pool
+    .text
     .p2align PAGE_SIZE_LOG2
 PATCH_LABEL ThunkPool
     .rept (THUNKS_MAP_SIZE / PAGE_SIZE)
     .p2align PAGE_SIZE_LOG2
     THUNKS_PAGE_BLOCK
     .endr
     .p2align PAGE_SIZE_LOG2
-    .section __THUNKS_DATA,__thunks,regular
-    .p2align PAGE_SIZE_LOG2
-    .space THUNKS_MAP_SIZE
-    .p2align PAGE_SIZE_LOG2
 #else
 #error Unsupported OS
 #endif

src/coreclr/nativeaot/Runtime/unix/PalRedhawkUnix.cpp

@@ -56,8 +56,7 @@
 #endif
 
 #ifdef TARGET_APPLE
-#include <minipal/getexepath.h>
-#include <mach-o/getsect.h>
+#include <mach/mach.h>
 #endif
 
 using std::nullptr_t;
@@ -516,59 +515,61 @@ extern "C" bool PalDetachThread(void* thread)
 
 #if !defined(USE_PORTABLE_HELPERS) && !defined(FEATURE_RX_THUNKS)
 
-#ifdef TARGET_APPLE
-static const struct section_64 *thunks_section;
-static const struct section_64 *thunks_data_section;
-#endif
-
 REDHAWK_PALEXPORT UInt32_BOOL REDHAWK_PALAPI PalAllocateThunksFromTemplate(HANDLE hTemplateModule, uint32_t templateRva, size_t templateSize, void** newThunksOut)
 {
 #ifdef TARGET_APPLE
-    int f;
-    Dl_info info;
+    vm_address_t addr, taddr;
+    vm_prot_t prot, max_prot;
+    kern_return_t ret;
 
-    int st = dladdr((const void*)hTemplateModule, &info);
-    if (st == 0)
+    // Allocate two contiguous ranges of memory: the first range will contain the trampolines
+    // and the second range will contain their data.
+    do
     {
-        return UInt32_FALSE;
-    }
+        ret = vm_allocate(mach_task_self(), &addr, templateSize * 2, VM_FLAGS_ANYWHERE);
+    } while (ret == KERN_ABORTED);
 
-    f = open(info.dli_fname, O_RDONLY);
-    if (f < 0)
+    if (ret != KERN_SUCCESS)
     {
         return UInt32_FALSE;
     }
 
-    // NOTE: We ignore templateRva since we would need to convert it to file offset
-    // and templateSize is useless too. Instead we read the sections from the
-    // executable and determine the size from them.
-    if (thunks_section == NULL)
+    do
+    {
+        ret = vm_remap(
+            mach_task_self(), &addr, templateSize, 0, VM_FLAGS_FIXED | VM_FLAGS_OVERWRITE,
+            mach_task_self(), ((vm_address_t)hTemplateModule + templateRva), FALSE, &prot, &max_prot, VM_INHERIT_SHARE);
+    } while (ret == KERN_ABORTED);
+
+    if (ret != KERN_SUCCESS)
     {
-        const struct mach_header_64 *hdr = (const struct mach_header_64 *)hTemplateModule;
-        thunks_section = getsectbynamefromheader_64(hdr, "__THUNKS", "__thunks");
-        thunks_data_section = getsectbynamefromheader_64(hdr, "__THUNKS_DATA", "__thunks");
+        do
+        {
+            ret = vm_deallocate(mach_task_self(), addr, templateSize * 2);
+        } while (ret == KERN_ABORTED);
+
+        return UInt32_FALSE;
     }
 
-    *newThunksOut = mmap(
-        NULL,
-        thunks_section->size + thunks_data_section->size,
-        PROT_READ | PROT_EXEC,
-        MAP_PRIVATE,
-        f,
-        thunks_section->offset);
-    close(f);
+    *newThunksOut = (void*)addr;
 
-    return *newThunksOut == NULL ? UInt32_FALSE : UInt32_TRUE;
+    return UInt32_TRUE;
 #else
     PORTABILITY_ASSERT("UNIXTODO: Implement this function");
 #endif
 }
 
-REDHAWK_PALEXPORT UInt32_BOOL REDHAWK_PALAPI PalFreeThunksFromTemplate(void *pBaseAddress)
+REDHAWK_PALEXPORT UInt32_BOOL REDHAWK_PALAPI PalFreeThunksFromTemplate(void *pBaseAddress, size_t templateSize)
 {
 #ifdef TARGET_APPLE
-    int ret = munmap(pBaseAddress, thunks_section->size + thunks_data_section->size);
-    return ret == 0 ? UInt32_TRUE : UInt32_FALSE;
+    kern_return_t ret;
+
+    do
+    {
+        ret = vm_deallocate(mach_task_self(), (vm_address_t)pBaseAddress, templateSize * 2);
+    } while (ret == KERN_ABORTED);
+
+    return ret == KERN_SUCCESS ? UInt32_TRUE : UInt32_FALSE;
 #else
     PORTABILITY_ASSERT("UNIXTODO: Implement this function");
 #endif

src/coreclr/nativeaot/Runtime/windows/PalRedhawkMinWin.cpp

@@ -258,7 +258,7 @@ REDHAWK_PALEXPORT UInt32_BOOL REDHAWK_PALAPI PalAllocateThunksFromTemplate(_In_
 #endif
 }
 
-REDHAWK_PALEXPORT UInt32_BOOL REDHAWK_PALAPI PalFreeThunksFromTemplate(_In_ void *pBaseAddress)
+REDHAWK_PALEXPORT UInt32_BOOL REDHAWK_PALAPI PalFreeThunksFromTemplate(_In_ void *pBaseAddress, size_t templateSize)
 {
 #ifdef XBOX_ONE
     return TRUE;