clear_cache_test.c revision 86277eb844c4983c81de62d7c050e92fe7155788 
1//===-- clear_cache_test.c - Test clear_cache -----------------------------===//
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}
21#else
22#include <sys/mman.h>
23extern void __clear_cache(void* start, void* end);
24#endif
25
26
27
28
29typedef int (*pfunc)(void);
30
31int func1()
32{
33    return 1;
34}
35
36int func2()
37{
38    return 2;
39}
40
41void *__attribute__((noinline))
42memcpy_f(void *dst, const void *src, size_t n) {
43// ARM and MIPS nartually align functions, but use the LSB for ISA selection
44// (THUMB, MIPS16/uMIPS respectively).  Ensure that the ISA bit is ignored in
45// the memcpy
46#if defined(__arm__) || defined(__mips__)
47  return (void *)((uintptr_t)memcpy(dst, (void *)((uintptr_t)src & ~1), n) |
48                  ((uintptr_t)src & 1));
49#else
50  return memcpy(dst, (void *)((uintptr_t)src), n);
51#endif
52}
53
54unsigned char execution_buffer[128];
55
56int main()
57{
58    // make executable the page containing execution_buffer
59    char* start = (char*)((uintptr_t)execution_buffer & (-4095));
60    char* end = (char*)((uintptr_t)(&execution_buffer[128+4096]) & (-4095));
61#if defined(_WIN32)
62    DWORD dummy_oldProt;
63    MEMORY_BASIC_INFORMATION b;
64    if (!VirtualQuery(start, &b, sizeof(b)))
65        return 1;
66    if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect))
67#else
68    if (mprotect(start, end-start, PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
69#endif
70        return 1;
71
72    // verify you can copy and execute a function
73    pfunc f1 = (pfunc)memcpy_f(execution_buffer, func1, 128);
74    __clear_cache(execution_buffer, &execution_buffer[128]);
75    if ((*f1)() != 1)
76        return 1;
77
78    // verify you can overwrite a function with another
79    pfunc f2 = (pfunc)memcpy_f(execution_buffer, func2, 128);
80    __clear_cache(execution_buffer, &execution_buffer[128]);
81    if ((*f2)() != 2)
82        return 1;
83
84    return 0;
85}
86