1 //===-- clear_cache_test.c - Test clear_cache -----------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 11 #include <stdio.h> 12 #include <string.h> 13 #include <stdint.h> 14 #include <sys/mman.h> 15 16 17 18 extern void __clear_cache(void* start, void* end); 19 20 typedef int (*pfunc)(void); 21 func1()22int func1() 23 { 24 return 1; 25 } 26 func2()27int func2() 28 { 29 return 2; 30 } 31 32 33 34 unsigned char execution_buffer[128]; 35 main()36int main() 37 { 38 // make executable the page containing execution_buffer 39 char* start = (char*)((uintptr_t)execution_buffer & (-4095)); 40 char* end = (char*)((uintptr_t)(&execution_buffer[128+4096]) & (-4095)); 41 if ( mprotect(start, end-start, PROT_READ|PROT_WRITE|PROT_EXEC) != 0 ) 42 return 1; 43 44 // verify you can copy and execute a function 45 memcpy(execution_buffer, (void *)(uintptr_t)&func1, 128); 46 __clear_cache(execution_buffer, &execution_buffer[128]); 47 pfunc f1 = (pfunc)(uintptr_t)execution_buffer; 48 if ( (*f1)() != 1 ) 49 return 1; 50 51 // verify you can overwrite a function with another 52 memcpy(execution_buffer, (void *)(uintptr_t)&func2, 128); 53 __clear_cache(execution_buffer, &execution_buffer[128]); 54 pfunc f2 = (pfunc)(uintptr_t)execution_buffer; 55 if ( (*f2)() != 2 ) 56 return 1; 57 58 return 0; 59 } 60