/* ===-- enable_execute_stack.c - Implement __enable_execute_stack ---------=== * * The LLVM Compiler Infrastructure * * This file is dual licensed under the MIT and the University of Illinois Open * Source Licenses. See LICENSE.TXT for details. * * ===----------------------------------------------------------------------=== */ #include "int_lib.h" #ifndef _WIN32 #include <sys/mman.h> #endif /* #include "config.h" * FIXME: CMake - include when cmake system is ready. * Remove #define HAVE_SYSCONF 1 line. */ #define HAVE_SYSCONF 1 #ifdef _WIN32 #define WIN32_LEAN_AND_MEAN #include <Windows.h> #else #ifndef __APPLE__ #include <unistd.h> #endif /* __APPLE__ */ #endif /* _WIN32 */ #if __LP64__ #define TRAMPOLINE_SIZE 48 #else #define TRAMPOLINE_SIZE 40 #endif /* * The compiler generates calls to __enable_execute_stack() when creating * trampoline functions on the stack for use with nested functions. * It is expected to mark the page(s) containing the address * and the next 48 bytes as executable. Since the stack is normally rw- * that means changing the protection on those page(s) to rwx. */ COMPILER_RT_ABI void __enable_execute_stack(void* addr) { #if _WIN32 MEMORY_BASIC_INFORMATION mbi; if (!VirtualQuery (addr, &mbi, sizeof(mbi))) return; /* We should probably assert here because there is no return value */ VirtualProtect (mbi.BaseAddress, mbi.RegionSize, PAGE_EXECUTE_READWRITE, &mbi.Protect); #else #if __APPLE__ /* On Darwin, pagesize is always 4096 bytes */ const uintptr_t pageSize = 4096; #elif !defined(HAVE_SYSCONF) #error "HAVE_SYSCONF not defined! See enable_execute_stack.c" #else const uintptr_t pageSize = sysconf(_SC_PAGESIZE); #endif /* __APPLE__ */ const uintptr_t pageAlignMask = ~(pageSize-1); uintptr_t p = (uintptr_t)addr; unsigned char* startPage = (unsigned char*)(p & pageAlignMask); unsigned char* endPage = (unsigned char*)((p+TRAMPOLINE_SIZE+pageSize) & pageAlignMask); size_t length = endPage - startPage; (void) mprotect((void *)startPage, length, PROT_READ | PROT_WRITE | PROT_EXEC); #endif }