From 75c4044b9a49faaeec245cc3a79a390dde7c804e Mon Sep 17 00:00:00 2001 From: Lukasz Majewski Date: Wed, 14 Oct 2020 13:45:43 +0200 Subject: y2038: linux: Provide __time64 implementation In the glibc the time function can use vDSO (on power and x86 the USE_IFUNC_TIME is defined), time syscall or 'default' time() from ./time/time.c (as a fallback). In this patch the last function (time) has been refactored and moved to ./sysdeps/unix/sysv/linux/time.c to be Linux specific. The new __time64 explicit 64 bit function for providing 64 bit value of seconds after epoch (by internally calling __clock_gettime64) has been introduced. Moreover, a 32 bit version - __time has been refactored to internally use __time64. The __time is now supposed to be used on systems still supporting 32 bit time (__TIMESIZE != 64) - hence the necessary check for time_t potential overflow. The iFUNC vDSO direct call optimization has been removed from both i686 and powerpc32 (USE_IFUNC_TIME is not defined for those architectures anymore). The Linux kernel does not provide a y2038 safe implementation of time 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_TIME 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 __time64 and __time. Reviewed-by: Adhemerval Zanella --- include/time.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'include') diff --git a/include/time.h b/include/time.h index edf6cdf..caf2af5 100644 --- a/include/time.h +++ b/include/time.h @@ -317,6 +317,13 @@ extern int __timespec_get64 (struct __timespec64 *ts, int base); libc_hidden_proto (__timespec_get64) #endif +#if __TIMESIZE == 64 +# define __time64 __time +#else +extern __time64_t __time64 (__time64_t *timer); +libc_hidden_proto (__time64) +#endif + /* Use in the clock_* functions. Size of the field representing the actual clock ID. */ #define CLOCK_IDFIELD_SIZE 3 -- cgit v1.1