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
41
42
43unsigned char execution_buffer[128];
44
45int main()
46{
47    // make executable the page containing execution_buffer
48    char* start = (char*)((uintptr_t)execution_buffer & (-4095));
49    char* end = (char*)((uintptr_t)(&execution_buffer[128+4096]) & (-4095));
50#if defined(_WIN32)
51    DWORD dummy_oldProt;
52    MEMORY_BASIC_INFORMATION b;
53    if (!VirtualQuery(start, &b, sizeof(b)))
54        return 1;
55    if (!VirtualProtect(b.BaseAddress, b.RegionSize, PAGE_EXECUTE_READWRITE, &b.Protect))
56#else
57    if (mprotect(start, end-start, PROT_READ|PROT_WRITE|PROT_EXEC) != 0)
58#endif
59        return 1;
60
61    // verify you can copy and execute a function
62    memcpy(execution_buffer, (void *)(uintptr_t)&func1, 128);
63    __clear_cache(execution_buffer, &execution_buffer[128]);
64    pfunc f1 = (pfunc)(uintptr_t)execution_buffer;
65    if ((*f1)() != 1)
66        return 1;
67
68    // verify you can overwrite a function with another
69    memcpy(execution_buffer, (void *)(uintptr_t)&func2, 128);
70    __clear_cache(execution_buffer, &execution_buffer[128]);
71    pfunc f2 = (pfunc)(uintptr_t)execution_buffer;
72    if ((*f2)() != 2)
73        return 1;
74
75    return 0;
76}
77