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>
15extern void __clear_cache(void* start, void* end);
16extern void __enable_execute_stack(void* addr);
17
18typedef int (*pfunc)(void);
19
20// Make these static to avoid ILT jumps for incremental linking on Windows.
21static int func1() { return 1; }
22static int func2() { return 2; }
23
24void *__attribute__((noinline))
25memcpy_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
37int 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