enable_execute_stack_test.c revision 1.1.1.2 
1//===-- enable_execute_stack_test.c - Test __enable_execute_stack ----------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is dual licensed under the MIT and the University of Illinois Open
6// Source Licenses. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10
11#include <stdio.h>
12#include <string.h>
13#include <stdint.h>
14#if defined(_WIN32)
15#include <windows.h>
16void __clear_cache(void* start, void* end)
17{
18    if (!FlushInstructionCache(GetCurrentProcess(), start, end-start))
19        exit(1);
20}
21void __enable_execute_stack(void *addr)
22{
23    MEMORY_BASIC_INFORMATION b;
24
25    if (!VirtualQuery(addr, &b, sizeof(b)))
26        exit(1);
27    if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect))
28        exit(1);
29}
30#else
31#include <sys/mman.h>
32extern void __clear_cache(void* start, void* end);
33extern void __enable_execute_stack(void* addr);
34#endif
35
36typedef int (*pfunc)(void);
37
38int func1()
39{
40    return 1;
41}
42
43int func2()
44{
45    return 2;
46}
47
48void *__attribute__((noinline))
49memcpy_f(void *dst, const void *src, size_t n) {
50// ARM and MIPS nartually align functions, but use the LSB for ISA selection
51// (THUMB, MIPS16/uMIPS respectively).  Ensure that the ISA bit is ignored in
52// the memcpy
53#if defined(__arm__) || defined(__mips__)
54  return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1), n) |
55                  ((uintptr_t)src & 1));
56#else
57  return memcpy(dst, (void *)((uintptr_t)src), n);
58#endif
59}
60
61int main()
62{
63    unsigned char execution_buffer[128];
64    // mark stack page containing execution_buffer to be executable
65    __enable_execute_stack(execution_buffer);
66
67    // verify you can copy and execute a function
68    pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
69    __clear_cache(execution_buffer, &execution_buffer[128]);
70    if ((*f1)() != 1)
71        return 1;
72
73    // verify you can overwrite a function with another
74    pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
75    __clear_cache(execution_buffer, &execution_buffer[128]);
76    if ((*f2)() != 2)
77        return 1;
78
79    return 0;
80}
81