1 // REQUIRES: native-run 2 // RUN: %clang_builtins %s %librt -o %t && %run %t 3 //===-- enable_execute_stack_test.c - Test __enable_execute_stack ----------===// 4 // 5 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 6 // See https://llvm.org/LICENSE.txt for license information. 7 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 8 // 9 //===----------------------------------------------------------------------===// 10 11 12 #include <stdio.h> 13 #include <string.h> 14 #include <stdint.h> 15 extern void __clear_cache(void* start, void* end); 16 extern void __enable_execute_stack(void* addr); 17 18 typedef int (*pfunc)(void); 19 20 // Make these static to avoid ILT jumps for incremental linking on Windows. 21 static int func1() { return 1; } 22 static int func2() { return 2; } 23 24 void *__attribute__((noinline)) 25 memcpy_f(void *dst, const void *src, size_t n) { 26 // ARM and MIPS nartually align functions, but use the LSB for ISA selection 27 // (THUMB, MIPS16/uMIPS respectively). Ensure that the ISA bit is ignored in 28 // the memcpy 29 #if defined(__arm__) || defined(__mips__) 30 return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1), n) | 31 ((uintptr_t)src & 1)); 32 #else 33 return memcpy(dst, (void *)((uintptr_t)src), n); 34 #endif 35 } 36 37 int main() 38 { 39 unsigned char execution_buffer[128]; 40 // mark stack page containing execution_buffer to be executable 41 __enable_execute_stack(execution_buffer); 42 43 // verify you can copy and execute a function 44 pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128); 45 __clear_cache(execution_buffer, &execution_buffer[128]); 46 printf("f1: %p\n", f1); 47 if ((*f1)() != 1) 48 return 1; 49 50 // verify you can overwrite a function with another 51 pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128); 52 __clear_cache(execution_buffer, &execution_buffer[128]); 53 if ((*f2)() != 2) 54 return 1; 55 56 return 0; 57 } 58