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4ebbefd6b9
This adds a new vdso_test.c that's written entirely in C. It also makes all of the vDSO examples work on 32-bit x86. Cc: Stefani Seibold <stefani@seibold.net> Signed-off-by: Andy Lutomirski <luto@amacapital.net> Link: http://lkml.kernel.org/r/62b701fc44b79f118ac2b2d64d19965fc5c291fb.1402620737.git.luto@amacapital.net Signed-off-by: H. Peter Anvin <hpa@zytor.com>
53 lines
1.2 KiB
C
53 lines
1.2 KiB
C
/*
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* vdso_test.c: Sample code to test parse_vdso.c
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* Copyright (c) 2014 Andy Lutomirski
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* Subject to the GNU General Public License, version 2
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*
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* Compile with:
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* gcc -std=gnu99 vdso_test.c parse_vdso.c
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*
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* Tested on x86, 32-bit and 64-bit. It may work on other architectures, too.
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*/
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#include <stdint.h>
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#include <elf.h>
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#include <stdio.h>
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#include <sys/auxv.h>
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#include <sys/time.h>
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extern void *vdso_sym(const char *version, const char *name);
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extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
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extern void vdso_init_from_auxv(void *auxv);
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int main(int argc, char **argv)
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{
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unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
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if (!sysinfo_ehdr) {
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printf("AT_SYSINFO_EHDR is not present!\n");
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return 0;
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}
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vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
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/* Find gettimeofday. */
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typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
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gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
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if (!gtod) {
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printf("Could not find __vdso_gettimeofday\n");
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return 1;
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}
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struct timeval tv;
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long ret = gtod(&tv, 0);
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if (ret == 0) {
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printf("The time is %lld.%06lld\n",
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(long long)tv.tv_sec, (long long)tv.tv_usec);
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} else {
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printf("__vdso_gettimeofday failed\n");
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}
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return 0;
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}
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