1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * vdso_test.c: Sample code to test parse_vdso.c 4 * Copyright (c) 2014 Andy Lutomirski 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 #include "../kselftest.h" 19 20 extern void *vdso_sym(const char *version, const char *name); 21 extern void vdso_init_from_sysinfo_ehdr(uintptr_t base); 22 extern void vdso_init_from_auxv(void *auxv); 23 24 /* 25 * ARM64's vDSO exports its gettimeofday() implementation with a different 26 * name and version from other architectures, so we need to handle it as 27 * a special case. 28 */ 29 #if defined(__aarch64__) 30 const char *version = "LINUX_2.6.39"; 31 const char *name = "__kernel_gettimeofday"; 32 #else 33 const char *version = "LINUX_2.6"; 34 const char *name = "__vdso_gettimeofday"; 35 #endif 36 37 int main(int argc, char **argv) 38 { 39 unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR); 40 if (!sysinfo_ehdr) { 41 printf("AT_SYSINFO_EHDR is not present!\n"); 42 return KSFT_SKIP; 43 } 44 45 vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR)); 46 47 /* Find gettimeofday. */ 48 typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); 49 gtod_t gtod = (gtod_t)vdso_sym(version, name); 50 51 if (!gtod) { 52 printf("Could not find %s\n", name); 53 return KSFT_SKIP; 54 } 55 56 struct timeval tv; 57 long ret = gtod(&tv, 0); 58 59 if (ret == 0) { 60 printf("The time is %lld.%06lld\n", 61 (long long)tv.tv_sec, (long long)tv.tv_usec); 62 } else { 63 printf("%s failed\n", name); 64 return KSFT_FAIL; 65 } 66 67 return 0; 68 } 69