/* * vdso_test.c: Sample code to test parse_vdso.c * Copyright (c) 2014 Andy Lutomirski * Subject to the GNU General Public License, version 2 * * Compile with: * gcc -std=gnu99 vdso_test.c parse_vdso.c * * Tested on x86, 32-bit and 64-bit. It may work on other architectures, too. */ #include <stdint.h> #include <elf.h> #include <stdio.h> #include <sys/auxv.h> #include <sys/time.h> #include "../kselftest.h" extern void *vdso_sym(const char *version, const char *name); extern void vdso_init_from_sysinfo_ehdr(uintptr_t base); extern void vdso_init_from_auxv(void *auxv); /* * ARM64's vDSO exports its gettimeofday() implementation with a different * name and version from other architectures, so we need to handle it as * a special case. */ #if defined(__aarch64__) const char *version = "LINUX_2.6.39"; const char *name = "__kernel_gettimeofday"; #else const char *version = "LINUX_2.6"; const char *name = "__vdso_gettimeofday"; #endif int main(int argc, char **argv) { unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR); if (!sysinfo_ehdr) { printf("AT_SYSINFO_EHDR is not present!\n"); return KSFT_SKIP; } vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR)); /* Find gettimeofday. */ typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz); gtod_t gtod = (gtod_t)vdso_sym(version, name); if (!gtod) { printf("Could not find %s\n", name); return KSFT_SKIP; } struct timeval tv; long ret = gtod(&tv, 0); if (ret == 0) { printf("The time is %lld.%06lld\n", (long long)tv.tv_sec, (long long)tv.tv_usec); } else { printf("%s failed\n", name); return KSFT_FAIL; } return 0; }