From: Lukasz Majewski <lukma@denx.de>
To: Stepan Golosunov <stepan@golosunov.pp.ru>
Cc: Joseph Myers <joseph@codesourcery.com>,
libc-alpha@sourceware.org, Arnd Bergmann <arnd@arndb.de>,
Paul Eggert <eggert@cs.ucla.edu>
Subject: Re: [PATCH v2 2/7] y2038: Introduce __ASSUME_64BIT_TIME define
Date: Mon, 6 May 2019 23:14:44 +0200 [thread overview]
Message-ID: <20190506231444.088274fc@jawa> (raw)
In-Reply-To: <20190506193617.nd44jtdt4tty5few@sghpc.golosunov.pp.ru>
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Hi Stepan,
> 06.05.2019 в 16:26:59 +0200 Lukasz Majewski написал:
>
> > > > > > > I believe that the only 32-bit architecture without
> > > > > > > __NR_clock_settime64 is x32.
> > > > > >
> > > > > > Ok, I see.
> > > > > >
> > > > > > Please correct me - would it be feasible to just #undef
> > > > > > __ASSYME_TIME64_SYSCALLS for x32 ?
> > > > >
> > > > > You'll need to know whether to use __NR_clock_settime64 or
> > > > > __NR_clock_settime in cases where __TIMESIZE == 64 and
> > > > > __WORDSIZE == 32.
> > >
> > > Please correct me, but I do have some doubts here.
> > >
> > > As x32 now uses 64 bit time (and has TIMESIZE==64) - it uses the
> > > clock_settime call (with in-kernel broken tv_nsec padding
> > > clearing - but for this the fix is in its way to upstream).
> > >
> > > Why does it need to also support clock_settime64 ?
> >
> > I was too eager to send the mail.
> >
> > It is connected with your proposition to use __WORDSIZE for #ifdef
> > on __ASSUME_TIME64_SYSCALLS.
> >
> > As x32 has __WORDSIZE=32 (but __TIMESIZE=64), it would fall into
> > "category" of archs using explicit 64 bit calls (i.e.
> > clock_settime64).
> >
> > However, for it - those shall be replaced with syscalls used up
> > till now (i.e. clock_settime).
> >
> > Am I right here ?
>
> x32 has __WORDSIZE==32 and __TIMESIZE==64. Future 32-bit
> architectures should have __WORDSIZE==32 and __TIMESIZE==64 too. And
> the only difference in implementation of clock_settime64 function
> there should be name of syscall (ignoring possible padding clearing
> issues).
For ARM, x86 there shall be call to clock_settime64 syscall
For x32 there shall be call to clock_settime syscall (which is
supporting 64 bit anyway - despite the ignoring possible padding
clearing issue).
>
> > > > > One way would be by defining __ASSUME_TIME64_SYSCALLS
> > > > > unconditionally on x32 and then defining __NR_clock_settime64
> > > > > to __NR_clock_settime when __ASSUME_TIME64_SYSCALLS is
> > > > > defined while __NR_clock_settime64 isn't.
>
> I think now that with this scheme __ASSUME_TIME64_SYSCALLS should be
> defined unconditionally for the __WORDSIZE==64 case too. With this
> there will be no need to use __TIMESIZE inside clock_settime64
> function. __TIMESIZE describes interfaces provided by glibc, and has
> no relation with kernel interfaces used by glibc.
>
> #ifdef __ASSUME_TIME64_SYSCALLS
> call __NR_clock_settime64 (possibly defined to __NR_clock_settime)
> #else
> call __NR_clock_settime64 with fallback to __NR_clock_settime on
> ENOSYS #endif
I rather thought about something like:
__clock_settime64 (clockid_t clock_id, const struct __timespec64 *tp)
{
<overflow check>
#ifdef __ASSUME_TIME64_SYSCALLS
# ifdef __NR_clock_settime64
int ret = INLINE_SYSCALL_CALL (clock_settime64, clock_id, tp);
if (ret == 0 || errno != ENOSYS)
return ret;
# endif
/* Fall back to syscall supporting 32bit struct timespec. */
struct timespec ts32;
valid_timespec64_to_timespec (tp, &ts32);
return INLINE_SYSCALL_CALL (clock_settime, clock_id, &ts32);
#else
/* 64 bit machines + x32 */
return INLINE_SYSCALL_CALL (clock_settime, clock_id, tp);
#endif
}
In the above pseudo code we assume that __ASSUME_TIME64_SYSCALLS is
#undef'ed for x32 (so it is treated as a 'special case' - in the same
way as x86_64).
Best regards,
Lukasz Majewski
--
DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
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next prev parent reply other threads:[~2019-05-06 21:15 UTC|newest]
Thread overview: 111+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-14 22:08 [PATCH 0/6] y2038: Linux: Provide __clock_* functions supporting 64 bit time Lukasz Majewski
2019-04-14 22:08 ` [PATCH 1/6] y2038: Introduce internal for glibc struct __timespec64 Lukasz Majewski
2019-04-14 22:08 ` [PATCH 2/6] y2038: Provide conversion helpers for " Lukasz Majewski
2019-04-14 22:08 ` [PATCH 3/6] y2038: linux: Provide __clock_settime64 implementation Lukasz Majewski
2019-04-17 22:08 ` Joseph Myers
2019-04-18 6:46 ` Lukasz Majewski
2019-04-20 0:20 ` Stepan Golosunov
2019-04-20 11:21 ` Lukasz Majewski
2019-04-22 9:07 ` Stepan Golosunov
2019-04-22 21:45 ` Arnd Bergmann
2019-04-23 15:45 ` Lukasz Majewski
2019-04-14 22:08 ` [PATCH 4/6] y2038: linux: Provide __clock_getres64 implementation Lukasz Majewski
2019-04-14 22:08 ` [PATCH 5/6] y2038: linux: Provide __clock_gettime64 implementation Lukasz Majewski
2019-04-14 22:08 ` [PATCH 6/6] y2038: linux: Provide __clock_nanosleep64 implementation Lukasz Majewski
2019-04-17 22:11 ` Joseph Myers
2019-04-18 5:54 ` Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 0/7] y2038: Linux: Provide __clock_* functions supporting 64 bit time Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 1/7] y2038: Introduce internal for glibc struct __timespec64 Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 2/7] y2038: Introduce __ASSUME_64BIT_TIME define Lukasz Majewski
2019-04-29 21:50 ` Joseph Myers
2019-04-30 9:05 ` Lukasz Majewski
2019-04-30 21:47 ` Stepan Golosunov
2019-05-02 8:51 ` Lukasz Majewski
2019-05-02 11:54 ` Stepan Golosunov
2019-05-02 13:55 ` Lukasz Majewski
2019-05-06 13:38 ` Lukasz Majewski
2019-05-06 14:26 ` Lukasz Majewski
2019-05-06 19:36 ` Stepan Golosunov
2019-05-06 21:14 ` Lukasz Majewski [this message]
2019-05-07 20:03 ` Stepan Golosunov
2019-05-07 20:44 ` Joseph Myers
2019-05-08 7:51 ` Lukasz Majewski
2019-05-08 19:48 ` Stepan Golosunov
2019-05-09 16:12 ` Joseph Myers
2019-05-16 4:00 ` Arnd Bergmann
2019-05-16 19:54 ` Stepan Golosunov
2019-05-16 19:59 ` Joseph Myers
2019-05-17 7:23 ` Florian Weimer
2019-05-17 8:34 ` Arnd Bergmann
2019-05-07 15:43 ` Joseph Myers
2019-05-02 15:04 ` Joseph Myers
2019-05-05 14:10 ` Stepan Golosunov
2019-05-05 20:46 ` Lukasz Majewski
2019-05-06 14:56 ` Lukasz Majewski
2019-05-07 15:35 ` Joseph Myers
2019-05-08 10:18 ` Lukasz Majewski
2019-05-09 15:46 ` Joseph Myers
2019-05-15 15:39 ` Lukasz Majewski
2019-05-16 3:57 ` Arnd Bergmann
2019-05-16 6:58 ` Lukasz Majewski
2019-05-31 11:37 ` Stepan Golosunov
2019-06-05 16:35 ` Lukasz Majewski
2019-06-06 6:50 ` Stepan Golosunov
2019-04-29 10:46 ` [PATCH v2 3/7] y2038: Provide conversion helpers for struct __timespec64 Lukasz Majewski
2019-05-02 11:56 ` Stepan Golosunov
2019-05-02 14:17 ` Lukasz Majewski
2019-05-02 15:59 ` Joseph Myers
2019-05-02 16:19 ` Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 4/7] y2038: linux: Provide __clock_settime64 implementation Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 5/7] y2038: linux: Provide __clock_getres64 implementation Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 6/7] y2038: linux: Provide __clock_gettime64 implementation Lukasz Majewski
2019-04-29 10:46 ` [PATCH v2 7/7] y2038: linux: Provide __clock_nanosleep64 implementation Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 0/5] y2038: Linux: Provide __clock_settime function supporting 64 bit time Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 1/5] y2038: Introduce __ASSUME_TIME64_SYSCALLS define Lukasz Majewski
2019-05-07 16:04 ` Joseph Myers
2019-05-07 13:18 ` [PATCH v3 2/5] y2038: Introduce internal for glibc struct __timespec64 Lukasz Majewski
2019-05-07 13:30 ` Andreas Schwab
2019-05-07 14:07 ` Lukasz Majewski
2019-05-07 14:13 ` Andreas Schwab
2019-05-08 8:32 ` Lukasz Majewski
2019-05-08 8:38 ` Andreas Schwab
2019-05-08 9:10 ` Lukasz Majewski
2019-05-08 9:12 ` Andreas Schwab
2019-05-08 9:37 ` Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 3/5] y2038: Provide conversion helpers for " Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 4/5] y2038: linux: Provide __clock_settime64 implementation Lukasz Majewski
2019-05-07 16:40 ` Joseph Myers
2019-05-07 13:18 ` [PATCH v3 5/5] y2038: Support for Y2038 safe time on 32 bit systems Lukasz Majewski
2019-05-07 16:37 ` Joseph Myers
2019-05-08 10:27 ` Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 0/5] y2038: Linux: Provide __clock_settime function supporting 64 bit time Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 1/5] y2038: Introduce __ASSUME_TIME64_SYSCALLS define Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 2/5] y2038: Introduce internal for glibc struct __timespec64 Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 3/5] y2038: Provide conversion helpers for " Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 4/5] y2038: linux: Provide __clock_settime64 implementation Lukasz Majewski
2019-05-07 13:18 ` [PATCH v3 5/5] y2038: Support for Y2038 safe time on 32 bit systems Lukasz Majewski
2019-05-07 13:34 ` Andreas Schwab
2019-05-08 15:56 ` [PATCH] y2038: Introduce __ASSUME_TIME64_SYSCALLS define Lukasz Majewski
2019-05-09 15:58 ` Joseph Myers
2019-05-09 16:18 ` Stepan Golosunov
2019-05-15 14:27 ` [PATCH v5] " Lukasz Majewski
2019-05-21 15:15 ` Lukasz Majewski
2019-05-23 7:34 ` Stepan Golosunov
2019-05-23 9:35 ` Lukasz Majewski
2019-05-25 16:19 ` Lukasz Majewski
2019-05-25 19:45 ` Stepan Golosunov
2019-05-26 12:39 ` Lukasz Majewski
2019-05-28 16:00 ` Lukasz Majewski
2019-05-28 19:53 ` Joseph Myers
2019-05-28 22:46 ` Lukasz Majewski
2019-05-28 22:50 ` Joseph Myers
2019-05-28 19:47 ` Joseph Myers
2019-05-28 22:09 ` Lukasz Majewski
2019-05-28 22:43 ` Joseph Myers
2019-05-23 21:17 ` Joseph Myers
2019-05-20 10:27 ` [PATCH v4 0/3] y2038: Linux: Provide __clock_settime64 function supporting 64 bit time Lukasz Majewski
2019-05-20 10:27 ` [PATCH v4 1/3] y2038: Introduce internal for glibc struct __timespec64 Lukasz Majewski
2019-05-20 10:27 ` [PATCH v4 2/3] y2038: Provide conversion helpers for " Lukasz Majewski
2019-05-20 10:27 ` [PATCH v4 3/3] y2038: linux: Provide __clock_settime64 implementation Lukasz Majewski
2019-05-23 7:08 ` Stepan Golosunov
2019-05-23 9:28 ` Lukasz Majewski
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