177ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao/* ===-- enable_execute_stack.c - Implement __enable_execute_stack ---------=== 277ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * 377ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * The LLVM Compiler Infrastructure 477ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * 577ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * This file is distributed under the University of Illinois Open Source 677ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * License. See LICENSE.TXT for details. 777ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * 877ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * ===----------------------------------------------------------------------=== 977ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao */ 1077ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 1177ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#include <stdint.h> 1277ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#include <sys/mman.h> 1377ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 1477ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao/* #include "config.h" 1577ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * FIXME: CMake - include when cmake system is ready. 1677ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * Remove #define HAVE_SYSCONF 1 line. 1777ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao */ 1877ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#define HAVE_SYSCONF 1 1977ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 2077ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#ifndef __APPLE__ 2177ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#include <unistd.h> 2277ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#endif /* __APPLE__ */ 2377ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 2477ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 2577ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao/* 2677ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * The compiler generates calls to __enable_execute_stack() when creating 2777ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * trampoline functions on the stack for use with nested functions. 2877ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * It is expected to mark the page(s) containing the address 2977ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * and the next 48 bytes as executable. Since the stack is normally rw- 3077ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao * that means changing the protection on those page(s) to rwx. 3177ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao */ 3277ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 3377ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liaovoid __enable_execute_stack(void* addr) 3477ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao{ 3577ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 3677ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#if __APPLE__ 3777ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao /* On Darwin, pagesize is always 4096 bytes */ 3877ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao const uintptr_t pageSize = 4096; 3977ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#elif !defined(HAVE_SYSCONF) 4077ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#error "HAVE_SYSCONF not defined! See enable_execute_stack.c" 4177ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#else 4277ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao const uintptr_t pageSize = sysconf(_SC_PAGESIZE); 4377ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao#endif /* __APPLE__ */ 4477ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 4577ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao const uintptr_t pageAlignMask = ~(pageSize-1); 4677ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao uintptr_t p = (uintptr_t)addr; 4777ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao unsigned char* startPage = (unsigned char*)(p & pageAlignMask); 4877ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao unsigned char* endPage = (unsigned char*)((p+48+pageSize) & pageAlignMask); 4977ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao size_t length = endPage - startPage; 5077ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao (void) mprotect((void *)startPage, length, PROT_READ | PROT_WRITE | PROT_EXEC); 5177ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao} 5277ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 5377ed6142daed1e068fbda64405d0de9845e40e1Shih-wei Liao 54