Re: [PATCH v7 0/3] y2038: Linux: Introduce __clock_settime64 function

[Lukasz Majewski <lukma at denx dot de>]

Hi Alistair,

> On Fri, Sep 6, 2019 at 7:59 AM Lukasz Majewski <lukma@denx.de> wrote:
> >
> > This patch set introduces the conversion of clock_settime to
> > explicit 64 bit struct __timespec64 arguments. As a result this
> > function is now Y2038 safe.
> >
> > This work is (loosely) based on a previous development/patches:
> > https://libc-alpha.sourceware.narkive.com/zniMOWui/rfc-patch-00-52-make-glibc-y2038-proof#post68
> >
> > Github branch (including the y2038 conversion example):
> > https://github.com/lmajewski/y2038_glibc/commits/glibc__clock_settime-conversion-v7
> >
> > Those patches have been applied on top of master branch:
> > SHA1: a26918cfda4bc4b9dad8aae1496e3ef7cbb63d96
> >
> > Shall be used with provided meta-y2038 for development and testing:
> > https://github.com/lmajewski/meta-y2038
> >
> > I've used guidelines from:
> > https://www.gnu.org/software/libc/manual/html_mono/libc.html
> > "D.2.1 64-bit time symbol handling in the GNU C Library"
> > to convert *clock_settime*.
> >
> > and most notably from:
> > https://sourceware.org/glibc/wiki/Y2038ProofnessDesign#clock_gettime.28.29
> >  
> 
> Thanks for the patches Lukassz!
> 
> With my RV32 port I see this failure when compiling:
> 

But I did not change the core code between v5 (to which you refer here):
https://patchwork.ozlabs.org/cover/1155397/
and then:
https://sourceware.org/ml/libc-alpha/2019-05/msg00661.html

and v7:
https://patchwork.ozlabs.org/patch/1159056/

(The only change in v6 was to use 32 bit call to clock_settime syscall
as requested by Arnd to facilitate validation on existing systems.
However, Joseph was against this change).

The notable change (but not in this patch set) was moving clock_settime
symbol solely to glibc (and it has been removed from librt).

> In file included from ../sysdeps/generic/hp-timing.h:23,
>                  from ../nptl/descr.h:27,
>                  from ../sysdeps/riscv/nptl/tls.h:41,
>                  from ../include/errno.h:25,
>                  from ../sysdeps/unix/sysv/linux/clock_settime.c:18:
> ../include/time.h:129:28: error: conflicting types for
> '__clock_settime' # define __clock_settime64 __clock_settime
>                             ^~~~~~~~~~~~~~~
> ../sysdeps/unix/sysv/linux/clock_settime.c:25:1: note: in expansion of
> macro '__clock_settime64'
>  __clock_settime64 (clockid_t clock_id, const struct __timespec64 *tp)
>  ^~~~~~~~~~~~~~~~~
> In file included from <command-line>:
> ../include/time.h:25:20: note: previous declaration of
> '__clock_settime' was here
>  libc_hidden_proto (__clock_settime)
>                     ^~~~~~~~~~~~~~~
> ./../include/libc-symbols.h:598:33: note: in definition of macro
> '__hidden_proto'
>    extern thread __typeof (name) name __hidden_proto_hiddenattr
> (attrs); ^~~~
> ./../include/libc-symbols.h:617:44: note: in expansion of macro
> 'hidden_proto' # define libc_hidden_proto(name, attrs...)
> hidden_proto (name, ##attrs) ^~~~~~~~~~~~
> ../include/time.h:25:1: note: in expansion of macro
> 'libc_hidden_proto' libc_hidden_proto (__clock_settime)
>  ^~~~~~~~~~~~~~~~~
> ../sysdeps/unix/sysv/linux/clock_settime.c:70:42: error: conflicting
> types for 'clock_settime'
>  versioned_symbol (libc, __clock_settime, clock_settime, GLIBC_2_17);
>                                           ^~~~~~~~~~~~~
> ./../include/libc-symbols.h:152:26: note: in definition of macro
> '_weak_alias' extern __typeof (name) aliasname __attribute__ ((weak,
> alias (#name))) \ ^~~~~~~~~
> ../include/shlib-compat.h:74:3: note: in expansion of macro
> 'weak_alias' weak_alias (local, symbol)
>    ^~~~~~~~~~
> ../sysdeps/unix/sysv/linux/clock_settime.c:70:1: note: in expansion of
> macro 'versioned_symbol'
>  versioned_symbol (libc, __clock_settime, clock_settime, GLIBC_2_17);
>  ^~~~~~~~~~~~~~~~
> In file included from ../include/time.h:2,
>                  from ../sysdeps/generic/hp-timing.h:23,
>                  from ../nptl/descr.h:27,
>                  from ../sysdeps/riscv/nptl/tls.h:41,
>                  from ../include/errno.h:25,
>                  from ../sysdeps/unix/sysv/linux/clock_settime.c:18:
> ../time/time.h:222:12: note: previous declaration of 'clock_settime'
> was here extern int clock_settime (clockid_t __clock_id, const struct
> timespec *__tp)
> 
> Which I can fix with this diff:
> 
> diff --git a/include/time.h b/include/time.h
> index 7ed3aa61d1d..28e2722de21 100644
> --- a/include/time.h
> +++ b/include/time.h
> @@ -125,13 +125,9 @@ extern __time64_t __timegm64 (struct tm *__tp)
> __THROW; libc_hidden_proto (__timegm64)
>  #endif
> 
> -#if __TIMESIZE == 64

What is the value of __TIMESIZE on your port? Is it 32 or 64 ?

Do you also #define __USE_TIME_BITS64	1 ?

> -# define __clock_settime64 __clock_settime
> -#else
>  extern int __clock_settime64 (clockid_t clock_id,
>                                const struct __timespec64 *tp);
>  libc_hidden_proto (__clock_settime64)
> -#endif
> 
>  /* Compute the `struct tm' representation of T,
>     offset OFFSET seconds east of UTC,
> diff --git a/sysdeps/unix/sysv/linux/clock_settime.c
> b/sysdeps/unix/sysv/linux/clock_settime.c
> index f5e084238a5..ab033c56ea9 100644
> --- a/sysdeps/unix/sysv/linux/clock_settime.c
> +++ b/sysdeps/unix/sysv/linux/clock_settime.c
> @@ -54,7 +54,6 @@ __clock_settime64 (clockid_t clock_id, const struct
> __timespec64 *tp)
>  #endif
>  }
> 
> -#if __TIMESIZE != 64

When I look on RISC-V patchset:
https://patchwork.ozlabs.org/patch/1155391/

for the __clock_nanosleep for example you follow the same convention.
And you don't need to remove #if __TIMESIZE != 64 for example.

One difference is that the clock_settime64 code will be Y2038 on e.g.
32 bit ARM only when I apply on top of it following patch:
https://github.com/lmajewski/y2038_glibc/commit/c6740c05ea9b224a552847d10402f98da8376994

(it enables redirect for clock_settime and support for -D_TIME_BITS=64
compilation flag).



>  int
>  __clock_settime (clockid_t clock_id, const struct timespec *tp)
>  {
> @@ -63,7 +62,6 @@ __clock_settime (clockid_t clock_id, const struct
> timespec *tp)
>    valid_timespec_to_timespec64 (tp, &ts64);
>    return __clock_settime64 (clock_id, &ts64);
>  }
> -#endif
> 
>  libc_hidden_def (__clock_settime)
> 
> Alistair
> 
> >
> >
> > Lukasz Majewski (3):
> >   y2038: Introduce internal for glibc struct __timespec64
> >   y2038: Provide conversion helpers for struct __timespec64
> >   y2038: linux: Provide __clock_settime64 implementation
> >
> >  include/time.h                          | 116
> > ++++++++++++++++++++++++ sysdeps/unix/sysv/linux/clock_settime.c |
> > 38 +++++++- 2 files changed, 150 insertions(+), 4 deletions(-)
> >
> > --
> > 2.20.1
> >  



Best regards,

Lukasz Majewski

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