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f9b6b0ef60
Remove vDSO from Makefile to move the to selftests. Update vDSO Makefile to work under selftests. vDSO will not be run as part of selftests suite and will not be included in install targets. They can be built separately for now. Acked-by: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
129 lines
2.8 KiB
C
129 lines
2.8 KiB
C
/*
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* vdso_test.c: Sample code to test parse_vdso.c on x86
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* Copyright (c) 2011-2014 Andy Lutomirski
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* Subject to the GNU General Public License, version 2
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*
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* You can amuse yourself by compiling with:
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* gcc -std=gnu99 -nostdlib
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* -Os -fno-asynchronous-unwind-tables -flto -lgcc_s
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* vdso_standalone_test_x86.c parse_vdso.c
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* to generate a small binary. On x86_64, you can omit -lgcc_s
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* if you want the binary to be completely standalone.
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*/
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#include <sys/syscall.h>
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#include <sys/time.h>
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#include <unistd.h>
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#include <stdint.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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/* We need a libc functions... */
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int strcmp(const char *a, const char *b)
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{
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/* This implementation is buggy: it never returns -1. */
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while (*a || *b) {
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if (*a != *b)
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return 1;
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if (*a == 0 || *b == 0)
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return 1;
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a++;
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b++;
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}
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return 0;
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}
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/* ...and two syscalls. This is x86-specific. */
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static inline long x86_syscall3(long nr, long a0, long a1, long a2)
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{
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long ret;
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#ifdef __x86_64__
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asm volatile ("syscall" : "=a" (ret) : "a" (nr),
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"D" (a0), "S" (a1), "d" (a2) :
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"cc", "memory", "rcx",
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"r8", "r9", "r10", "r11" );
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#else
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asm volatile ("int $0x80" : "=a" (ret) : "a" (nr),
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"b" (a0), "c" (a1), "d" (a2) :
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"cc", "memory" );
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#endif
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return ret;
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}
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static inline long linux_write(int fd, const void *data, size_t len)
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{
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return x86_syscall3(__NR_write, fd, (long)data, (long)len);
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}
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static inline void linux_exit(int code)
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{
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x86_syscall3(__NR_exit, code, 0, 0);
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}
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void to_base10(char *lastdig, time_t n)
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{
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while (n) {
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*lastdig = (n % 10) + '0';
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n /= 10;
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lastdig--;
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}
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}
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__attribute__((externally_visible)) void c_main(void **stack)
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{
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/* Parse the stack */
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long argc = (long)*stack;
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stack += argc + 2;
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/* Now we're pointing at the environment. Skip it. */
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while(*stack)
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stack++;
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stack++;
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/* Now we're pointing at auxv. Initialize the vDSO parser. */
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vdso_init_from_auxv((void *)stack);
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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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linux_exit(1);
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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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char buf[] = "The time is .000000\n";
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to_base10(buf + 31, tv.tv_sec);
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to_base10(buf + 38, tv.tv_usec);
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linux_write(1, buf, sizeof(buf) - 1);
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} else {
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linux_exit(ret);
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}
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linux_exit(0);
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}
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/*
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* This is the real entry point. It passes the initial stack into
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* the C entry point.
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*/
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asm (
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".text\n"
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".global _start\n"
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".type _start,@function\n"
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"_start:\n\t"
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#ifdef __x86_64__
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"mov %rsp,%rdi\n\t"
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"jmp c_main"
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#else
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"push %esp\n\t"
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"call c_main\n\t"
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"int $3"
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#endif
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);
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