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In the glibc the gettimeofday can use vDSO (on power and x86 the USE_IFUNC_GETTIMEOFDAY is defined), gettimeofday syscall or 'default' ___gettimeofday() from ./time/gettime.c (as a fallback). In this patch the last function (___gettimeofday) has been refactored and moved to ./sysdeps/unix/sysv/linux/gettimeofday.c to be Linux specific. The new __gettimeofday64 explicit 64 bit function for getting 64 bit time from the kernel (by internally calling __clock_gettime64) has been introduced. Moreover, a 32 bit version - __gettimeofday has been refactored to internally use __gettimeofday64. The __gettimeofday is now supposed to be used on systems still supporting 32 bit time (__TIMESIZE != 64) - hence the necessary check for time_t potential overflow and conversion of struct __timeval64 to 32 bit struct timespec. The iFUNC vDSO direct call optimization has been removed from both i686 and powerpc32 (USE_IFUNC_GETTIMEOFDAY is not defined for those architectures anymore). The Linux kernel does not provide a y2038 safe implementation of gettimeofday neither it plans to provide it in the future, clock_gettime64 should be used instead. Keeping support for this optimization would require to handle another build permutation (!__ASSUME_TIME64_SYSCALLS && USE_IFUNC_GETTIMEOFDAY) which adds more complexity and has limited use (since the idea is to eventually have a y2038 safe glibc build). Build tests: ./src/scripts/build-many-glibcs.py glibcs Run-time tests: - Run specific tests on ARM/x86 32bit systems (qemu): https://github.com/lmajewski/meta-y2038 and run tests: https://github.com/lmajewski/y2038-tests/commits/master Above tests were performed with Y2038 redirection applied as well as without to test proper usage of both __gettimeofday64 and __gettimeofday. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> [Including some commit message improvement]
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
/* gettimeofday - set time. Linux version.
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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/* Optimize the function call by setting the PLT directly to vDSO symbol. */
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#ifdef USE_IFUNC_GETTIMEOFDAY
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# include <time.h>
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# include <string.h>
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# include <sysdep.h>
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# include <sysdep-vdso.h>
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# ifdef SHARED
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# include <dl-vdso.h>
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# include <libc-vdso.h>
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static int
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__gettimeofday_syscall (struct timeval *restrict tv, void *restrict tz)
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{
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if (__glibc_unlikely (tz != 0))
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memset (tz, 0, sizeof *tz);
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return INLINE_SYSCALL_CALL (gettimeofday, tv, tz);
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}
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# undef INIT_ARCH
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# define INIT_ARCH() \
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void *vdso_gettimeofday = dl_vdso_vsym (HAVE_GETTIMEOFDAY_VSYSCALL)
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libc_ifunc (__gettimeofday,
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vdso_gettimeofday ? VDSO_IFUNC_RET (vdso_gettimeofday)
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: (void *) __gettimeofday_syscall)
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# else
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int
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__gettimeofday (struct timeval *restrict tv, void *restrict tz)
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{
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if (__glibc_unlikely (tz != 0))
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memset (tz, 0, sizeof *tz);
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return INLINE_VSYSCALL (gettimeofday, 2, tv, tz);
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}
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# endif
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weak_alias (__gettimeofday, gettimeofday)
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#else /* USE_IFUNC_GETTIMEOFDAY */
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/* Conversion of gettimeofday function to support 64 bit time on archs
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with __WORDSIZE == 32 and __TIMESIZE == 32/64 */
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#include <errno.h>
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int
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__gettimeofday64 (struct __timeval64 *restrict tv, void *restrict tz)
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{
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if (__glibc_unlikely (tz != 0))
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memset (tz, 0, sizeof (struct timezone));
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struct __timespec64 ts64;
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if (__clock_gettime64 (CLOCK_REALTIME, &ts64))
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return -1;
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*tv = timespec64_to_timeval64 (ts64);
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return 0;
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}
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# if __TIMESIZE != 64
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libc_hidden_def (__gettimeofday64)
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int
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__gettimeofday (struct timeval *restrict tv, void *restrict tz)
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{
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struct __timeval64 tv64;
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if (__gettimeofday64 (&tv64, tz))
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return -1;
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if (! in_time_t_range (tv64.tv_sec))
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{
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__set_errno (EOVERFLOW);
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return -1;
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}
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*tv = valid_timeval64_to_timeval (tv64);
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return 0;
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}
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# endif
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weak_alias (__gettimeofday, gettimeofday)
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#endif
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