1*3cab2bb3Spatrick //===-- enable_execute_stack.c - Implement __enable_execute_stack ---------===// 2*3cab2bb3Spatrick // 3*3cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*3cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information. 5*3cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*3cab2bb3Spatrick // 7*3cab2bb3Spatrick //===----------------------------------------------------------------------===// 8*3cab2bb3Spatrick 9*3cab2bb3Spatrick #include "int_lib.h" 10*3cab2bb3Spatrick 11*3cab2bb3Spatrick #ifndef _WIN32 12*3cab2bb3Spatrick #include <sys/mman.h> 13*3cab2bb3Spatrick #endif 14*3cab2bb3Spatrick 15*3cab2bb3Spatrick // #include "config.h" 16*3cab2bb3Spatrick // FIXME: CMake - include when cmake system is ready. 17*3cab2bb3Spatrick // Remove #define HAVE_SYSCONF 1 line. 18*3cab2bb3Spatrick #define HAVE_SYSCONF 1 19*3cab2bb3Spatrick 20*3cab2bb3Spatrick #ifdef _WIN32 21*3cab2bb3Spatrick #define WIN32_LEAN_AND_MEAN 22*3cab2bb3Spatrick #include <windows.h> 23*3cab2bb3Spatrick #else 24*3cab2bb3Spatrick #ifndef __APPLE__ 25*3cab2bb3Spatrick #include <unistd.h> 26*3cab2bb3Spatrick #endif // __APPLE__ 27*3cab2bb3Spatrick #endif // _WIN32 28*3cab2bb3Spatrick 29*3cab2bb3Spatrick #if __LP64__ 30*3cab2bb3Spatrick #define TRAMPOLINE_SIZE 48 31*3cab2bb3Spatrick #else 32*3cab2bb3Spatrick #define TRAMPOLINE_SIZE 40 33*3cab2bb3Spatrick #endif 34*3cab2bb3Spatrick 35*3cab2bb3Spatrick // The compiler generates calls to __enable_execute_stack() when creating 36*3cab2bb3Spatrick // trampoline functions on the stack for use with nested functions. 37*3cab2bb3Spatrick // It is expected to mark the page(s) containing the address 38*3cab2bb3Spatrick // and the next 48 bytes as executable. Since the stack is normally rw- 39*3cab2bb3Spatrick // that means changing the protection on those page(s) to rwx. 40*3cab2bb3Spatrick __enable_execute_stack(void * addr)41*3cab2bb3SpatrickCOMPILER_RT_ABI void __enable_execute_stack(void *addr) { 42*3cab2bb3Spatrick 43*3cab2bb3Spatrick #if _WIN32 44*3cab2bb3Spatrick MEMORY_BASIC_INFORMATION mbi; 45*3cab2bb3Spatrick if (!VirtualQuery(addr, &mbi, sizeof(mbi))) 46*3cab2bb3Spatrick return; // We should probably assert here because there is no return value 47*3cab2bb3Spatrick VirtualProtect(mbi.BaseAddress, mbi.RegionSize, PAGE_EXECUTE_READWRITE, 48*3cab2bb3Spatrick &mbi.Protect); 49*3cab2bb3Spatrick #else 50*3cab2bb3Spatrick #if __APPLE__ 51*3cab2bb3Spatrick // On Darwin, pagesize is always 4096 bytes 52*3cab2bb3Spatrick const uintptr_t pageSize = 4096; 53*3cab2bb3Spatrick #elif !defined(HAVE_SYSCONF) 54*3cab2bb3Spatrick #error "HAVE_SYSCONF not defined! See enable_execute_stack.c" 55*3cab2bb3Spatrick #else 56*3cab2bb3Spatrick const uintptr_t pageSize = sysconf(_SC_PAGESIZE); 57*3cab2bb3Spatrick #endif // __APPLE__ 58*3cab2bb3Spatrick 59*3cab2bb3Spatrick const uintptr_t pageAlignMask = ~(pageSize - 1); 60*3cab2bb3Spatrick uintptr_t p = (uintptr_t)addr; 61*3cab2bb3Spatrick unsigned char *startPage = (unsigned char *)(p & pageAlignMask); 62*3cab2bb3Spatrick unsigned char *endPage = 63*3cab2bb3Spatrick (unsigned char *)((p + TRAMPOLINE_SIZE + pageSize) & pageAlignMask); 64*3cab2bb3Spatrick size_t length = endPage - startPage; 65*3cab2bb3Spatrick (void)mprotect((void *)startPage, length, PROT_READ | PROT_WRITE | PROT_EXEC); 66*3cab2bb3Spatrick #endif 67*3cab2bb3Spatrick } 68