Based on kernel version 4.8. Page generated on 2016-10-06 23:19 EST.
1 /* 2 * vdso_test.c: Sample code to test parse_vdso.c 3 * Copyright (c) 2014 Andy Lutomirski 4 * Subject to the GNU General Public License, version 2 5 * 6 * Compile with: 7 * gcc -std=gnu99 vdso_test.c parse_vdso.c 8 * 9 * Tested on x86, 32-bit and 64-bit. It may work on other architectures, too. 10 */ 11 12 #include <stdint.h> 13 #include <elf.h> 14 #include <stdio.h> 15 #include <sys/auxv.h> 16 #include <sys/time.h> 17 18 extern void *vdso_sym(const char *version, const char *name); 19 extern void vdso_init_from_sysinfo_ehdr(uintptr_t base); 20 extern void vdso_init_from_auxv(void *auxv); 21 22 int main(int argc, char **argv) 23 { 24 unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR); 25 if (!sysinfo_ehdr) { 26 printf("AT_SYSINFO_EHDR is not present!\n"); 27 return 0; 28 } 29 30 vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR)); 31 32 /* Find gettimeofday. */ 33 typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); 34 gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday"); 35 36 if (!gtod) { 37 printf("Could not find __vdso_gettimeofday\n"); 38 return 1; 39 } 40 41 struct timeval tv; 42 long ret = gtod(&tv, 0); 43 44 if (ret == 0) { 45 printf("The time is %lld.%06lld\n", 46 (long long)tv.tv_sec, (long long)tv.tv_usec); 47 } else { 48 printf("__vdso_gettimeofday failed\n"); 49 } 50 51 return 0; 52 }