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> 16 void __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> 23 extern void __clear_cache(void* start, void* end); 24 #endif 25 26 27 28 29 typedef int (*pfunc)(void); 30 31 int func1() 32 { 33 return 1; 34 } 35 36 int func2() 37 { 38 return 2; 39 } 40 41 42 43 unsigned char execution_buffer[128]; 44 45 int 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
