From: Ben Hutchings <ben.hutchings@codethink.co.uk>
To: Deepa Dinamani <deepa.kernel@gmail.com>,
tglx@linutronix.de, john.stultz@linaro.org
Cc: y2038@lists.linaro.org, linux-arch@vger.kernel.org,
linux-kernel@vger.kernel.org, arnd@arndb.de
Subject: Re: [Y2038] [PATCH v2 07/10] include: Add new y2038 safe __kernel_timespec
Date: Fri, 15 Dec 2017 00:11:38 +0000 [thread overview]
Message-ID: <1513296698.18523.291.camel@codethink.co.uk> (raw)
In-Reply-To: <20171127193037.8711-8-deepa.kernel@gmail.com>
On Mon, 2017-11-27 at 11:30 -0800, Deepa Dinamani wrote:
> The new struct __kernel_timespec is similar to current
> internal kernel struct timespec64 on 64 bit architecture.
> The compat structure however is similar to below on little
> endian systems (padding and tv_nsec are switched for big
> endian systems):
>
> typedef s32 compat_long_t;
> typedef s64 compat_kernel_time64_t;
>
> struct compat_kernel_timespec {
> compat_kernel_time64_t tv_sec;
> compat_long_t tv_nsec;
> compat_long_t padding;
> };
>
> This allows for both the native and compat representations to
> be the same and syscalls using this type as part of their ABI
> can have a single entry point to both.
>
> Note that the compat define is not included anywhere in the
> kernel explicitly to avoid confusion.
If I understand correctly, the intent here is that C libraries will be
allowed to define struct timespec like that when appropriate feature
macros are enabled. Could you spell that out in the commit message,
and also the need to clear padding on the kernel side?
[...]
> --- a/include/uapi/linux/time.h
> +++ b/include/uapi/linux/time.h
> @@ -42,6 +42,13 @@ struct itimerval {
> > > struct timeval it_value; /* current value */
> };
>
> +#ifndef __kernel_timespec
> +struct __kernel_timespec {
> + __kernel_time64_t tv_sec; /* seconds */
> + long long tv_nsec; /* nanoseconds */
> +};
> +#endif
I wonder if it makes sense to override the alignment of this structure?
(64-bit types are aligned differently on 32-bit vs 64-bit x86, but not
other compat cases.) It might reduce the need for conversions in
compat code elsewhere later.
Ben.
> /*
> * The IDs of the various system clocks (for POSIX.1b interval timers):
> */
--
Ben Hutchings
Software Developer, Codethink Ltd.
next prev parent reply other threads:[~2017-12-15 0:11 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-27 19:30 [PATCH v2 00/10] posix_clocks: Prepare syscalls for 64 bit time_t conversion Deepa Dinamani
2017-11-27 19:30 ` Deepa Dinamani
2017-11-27 19:30 ` Deepa Dinamani
2017-11-27 19:30 ` Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 01/10] compat: Make compat helpers independent of CONFIG_COMPAT Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 02/10] include: Move compat_timespec/ timeval to compat_time.h Deepa Dinamani
2017-11-27 19:30 ` Deepa Dinamani
2017-11-27 19:30 ` Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 03/10] compat: enable compat_get/put_timespec64 always Deepa Dinamani
2017-12-14 23:27 ` [Y2038] " Ben Hutchings
2018-01-07 16:28 ` Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 04/10] arch: introduce CONFIG_64BIT_TIME Deepa Dinamani
2017-12-14 23:22 ` [Y2038] " Ben Hutchings
2017-11-27 19:30 ` [PATCH v2 05/10] arch: Introduce CONFIG_COMPAT_32BIT_TIME Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 06/10] posix-clocks: Make compat syscalls depend on CONFIG_COMPAT_32BIT_TIME Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 07/10] include: Add new y2038 safe __kernel_timespec Deepa Dinamani
2017-12-15 0:11 ` Ben Hutchings [this message]
2017-12-15 10:36 ` [Y2038] " Arnd Bergmann
2017-12-15 10:36 ` Arnd Bergmann
2017-11-27 19:30 ` [PATCH v2 08/10] fix get_timespec64() for y2038 safe compat interfaces Deepa Dinamani
2017-12-15 0:21 ` [Y2038] " Ben Hutchings
2017-12-15 12:02 ` Arnd Bergmann
2017-12-17 23:51 ` Ben Hutchings
2017-12-18 5:11 ` Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 09/10] change time types to new y2038 safe __kernel_* types Deepa Dinamani
2017-11-27 19:30 ` [PATCH v2 10/10] nanosleep: change time types to " Deepa Dinamani
2017-11-27 19:30 ` Deepa Dinamani
2017-12-15 0:31 ` [Y2038] " Ben Hutchings
2017-12-15 0:31 ` Ben Hutchings
2017-11-27 21:58 ` [PATCH v2 00/10] posix_clocks: Prepare syscalls for 64 bit time_t conversion Arnd Bergmann
2017-11-27 21:58 ` Arnd Bergmann
2017-11-27 21:58 ` Arnd Bergmann
2017-11-27 21:58 ` Arnd Bergmann
2017-11-27 22:29 ` Deepa Dinamani
2017-11-27 22:29 ` Deepa Dinamani
2017-11-27 22:29 ` Deepa Dinamani
2017-11-27 22:29 ` Deepa Dinamani
2017-11-28 14:17 ` Arnd Bergmann
2017-11-28 14:17 ` Arnd Bergmann
2017-11-28 14:17 ` Arnd Bergmann
2017-11-28 14:17 ` Arnd Bergmann
2017-11-28 23:17 ` Deepa Dinamani
2017-11-28 23:17 ` Deepa Dinamani
2017-11-28 23:17 ` Deepa Dinamani
2017-11-28 23:17 ` Deepa Dinamani
2017-11-29 21:12 ` Arnd Bergmann
2017-11-29 21:12 ` Arnd Bergmann
2017-11-29 21:12 ` Arnd Bergmann
2017-11-29 21:12 ` Arnd Bergmann
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