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>
__clear_cache(void * start,void * end)16 void __clear_cache(void* start, void* end)
17 {
18 if (!FlushInstructionCache(GetCurrentProcess(), start, end-start))
19 exit(1);
20 }
__enable_execute_stack(void * addr)21 void __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>
32 extern void __clear_cache(void* start, void* end);
33 extern void __enable_execute_stack(void* addr);
34 #endif
35
36 typedef int (*pfunc)(void);
37
func1()38 int func1()
39 {
40 return 1;
41 }
42
func2()43 int func2()
44 {
45 return 2;
46 }
47
48 void *__attribute__((noinline))
memcpy_f(void * dst,const void * src,size_t n)49 memcpy_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
main()61 int 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