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References: <20200214163134.31601-1-alistair.francis@wdc.com>
 <20200214163134.31601-6-alistair.francis@wdc.com> <20200215172645.4ea3375d@jawa>
In-Reply-To: <20200215172645.4ea3375d@jawa>
From: Alistair Francis <alistair23@gmail.com>
Date: Tue, 18 Feb 2020 19:02:00 -0000
Message-ID: <CAKmqyKOjvacUFmtA8ajjs0CjfbccY+jU-ssFYGB7MoAd=VKJJw@mail.gmail.com>
Subject: Re: [PATCH v3 5/8] linux: Use long time_t __getitimer/__setitimer
To: Lukasz Majewski <lukma@denx.de>
Cc: Alistair Francis <alistair.francis@wdc.com>, GNU C Library <libc-alpha@sourceware.org>
Content-Type: text/plain; charset="UTF-8"
X-SW-Source: 2020-02/txt/msg00803.txt.bz2

On Sat, Feb 15, 2020 at 8:26 AM Lukasz Majewski <lukma@denx.de> wrote:
>
> Hi Alistair,
>
> > The Linux kernel expects itimerval to use a 32-bit time_t, even on
> > archs with a 64-bit time_t (like RV32). To address this let's convert
> > itimerval to/from 32-bit and 64-bit to ensure the kernel always gets
> > a 32-bit time_t.
> >
> > While we are converting these functions let's also convert them to be
> > the y2038 safe versions. This means there is a *64 function that is
> > called by a backwards compatible wrapper.
> > ---
> >  include/time.h                        | 15 +++++
> >  sysdeps/unix/sysv/linux/getitimer.c   | 61 +++++++++++++++++
> >  sysdeps/unix/sysv/linux/setitimer.c   | 95
> > +++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/tv32-compat.h |
> > 35 ++++++++++ 4 files changed, 206 insertions(+)
> >  create mode 100644 sysdeps/unix/sysv/linux/getitimer.c
> >  create mode 100644 sysdeps/unix/sysv/linux/setitimer.c
> >  create mode 100644 sysdeps/unix/sysv/linux/tv32-compat.h
> >
> > diff --git a/include/time.h b/include/time.h
> > index 34dffaf95f..cdaf461c3f 100644
> > --- a/include/time.h
> > +++ b/include/time.h
> > @@ -6,6 +6,7 @@
> >  # include <bits/types/locale_t.h>
> >  # include <stdbool.h>
> >  # include <time/mktime-internal.h>
> > +# include <sys/time.h>
> >  # include <endian.h>
> >  # include <time-clockid.h>
> >  # include <sys/time.h>
> > @@ -119,6 +120,20 @@ struct __itimerval64
> >  };
> >  #endif
> >
> > +#if __TIMESIZE == 64
> > +# define __getitimer64 __getitimer
> > +# define __setitimer64 __setitimer
> > +#else
> > +extern int __getitimer64 (enum __itimer_which __which,
> > +                          struct __itimerval64 *__value);
> > +
> > +libc_hidden_proto (__getitimer64)
> > +extern int __setitimer64 (enum __itimer_which __which,
> > +                          const struct __itimerval64 *__restrict
> > __new,
> > +                          struct __itimerval64 *__restrict __old);
> > +libc_hidden_proto (__setitimer64)
> > +#endif
> > +
> >  #if __TIMESIZE == 64
> >  # define __ctime64 ctime
> >  #else
> > diff --git a/sysdeps/unix/sysv/linux/getitimer.c
> > b/sysdeps/unix/sysv/linux/getitimer.c new file mode 100644
> > index 0000000000..62d58a7af5
> > --- /dev/null
> > +++ b/sysdeps/unix/sysv/linux/getitimer.c
> > @@ -0,0 +1,61 @@
> > +/* getitimer -- Get the state of an interval timer.  Linux/tv32
> > version.
> > +   Copyright (C) 2020 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be
> > useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#include <time.h>
> > +#include <sys/time.h>
> > +#include <sys/types.h>
> > +#include <sysdep.h>
> > +#include <tv32-compat.h>
> > +
> > +int
> > +__getitimer64 (__itimer_which_t which, struct __itimerval64
> > *curr_value) +{
> > +
>
> Minor - please remove this blank line.
>
> > +#if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
> > +  return INLINE_SYSCALL_CALL (getitimer, which, curr_value);
> > +#else
> > +  struct __itimerval32 curr_value_32;
> > +  if (INLINE_SYSCALL_CALL (getitimer, which, &curr_value_32) == -1)
> > +    return -1;
> > +
> > +  /* Write all fields of 'curr_value' regardless of overflow.  */
> > +  curr_value->it_interval
> > +    = valid_timeval32_to_timeval64 (curr_value_32.it_interval);
> > +  curr_value->it_value
> > +    = valid_timeval32_to_timeval64 (curr_value_32.it_value);
> > +  return 0;
> > +#endif
> > +}
> > +
> > +
>
> Minor - please remove one blank line.

Good catch, I have removed both of these.

>
> > +#if __TIMESIZE != 64
> > +libc_hidden_def (__getitimer64)
> > +int
> > +__getitimer (__itimer_which_t which, struct itimerval *curr_value)
> > +{
> > +  struct __itimerval64 val64;
> > +
> > +  val64.it_interval
> > +    = valid_timeval_to_timeval64 (curr_value->it_interval);
> > +  val64.it_value
> > +    = valid_timeval_to_timeval64 (curr_value->it_value);
> > +
> > +  return __getitimer64 (which, &val64);
> > +}
> > +#endif
> > +weak_alias (__getitimer, getitimer)
> > diff --git a/sysdeps/unix/sysv/linux/setitimer.c
> > b/sysdeps/unix/sysv/linux/setitimer.c new file mode 100644
> > index 0000000000..238853dd33
> > --- /dev/null
> > +++ b/sysdeps/unix/sysv/linux/setitimer.c
> > @@ -0,0 +1,95 @@
> > +/* setitimer -- Set the state of an interval timer.  Linux/tv32
> > version.
> > +   Copyright (C) 2020 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be
> > useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#include <time.h>
> > +#include <sys/time.h>
> > +#include <sys/types.h>
> > +#include <sysdep.h>
> > +#include <tv32-compat.h>
> > +
> > +int
> > +__setitimer64 (__itimer_which_t which,
> > +               const struct __itimerval64 *restrict new_value,
> > +               struct __itimerval64 *restrict old_value)
> > +{
> > +#if __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64
> > +  return INLINE_SYSCALL_CALL (setitimer, which, new_value,
> > old_value); +#else
> > +  struct __itimerval32 new_value_32;
> > +
> > +  if (! in_time_t_range (new_value->it_interval.tv_sec))
> > +  {
> > +    __set_errno (EOVERFLOW);
> > +    return -1;
> > +  }
> > +  new_value_32.it_interval
> > +    = valid_timeval64_to_timeval32 (new_value->it_interval);
> > +
> > +  if (! in_time_t_range (new_value->it_value.tv_sec))
> > +  {
> > +    __set_errno (EOVERFLOW);
> > +    return -1;
> > +  }
> > +  new_value_32.it_value
> > +    = valid_timeval64_to_timeval32 (new_value->it_value);
> > +
> > +  if (old_value == NULL)
> > +    return INLINE_SYSCALL_CALL (setitimer, which, &new_value_32,
> > NULL); +
> > +  struct __itimerval32 old_value_32;
> > +  if (INLINE_SYSCALL_CALL (setitimer, which, &new_value_32,
> > &old_value_32) == -1)
> > +    return -1;
> > +
> > +  /* Write all fields of 'old_value' regardless of overflow.  */
> > +  old_value->it_interval
> > +     = valid_timeval32_to_timeval64 (old_value_32.it_interval);
> > +  old_value->it_value
> > +     = valid_timeval32_to_timeval64 (old_value_32.it_value);
> > +  return 0;
> > +#endif
> > +}
> > +
> > +#if __TIMESIZE != 64
> > +libc_hidden_def (__setitimer64)
> > +int
> > +__setitimer (__itimer_which_t which,
> > +             const struct itimerval *restrict new_value,
> > +             struct itimerval *restrict old_value)
> > +{
> > +  int ret;
> > +  struct __itimerval64 new64, old64;
> > +
> > +  new64.it_interval
> > +    = valid_timeval_to_timeval64 (new_value->it_interval);
> > +  new64.it_value
> > +    = valid_timeval_to_timeval64 (new_value->it_value);
> > +
> > +  ret = __setitimer64 (which, &new64, old_value ? &old64 : NULL);
> > +
> > +  if (ret == 0 && old_value)
> > +    {
> > +      old_value->it_interval
> > +        = valid_timeval64_to_timeval (old64.it_interval);
> > +      old_value->it_value
> > +        = valid_timeval64_to_timeval (old64.it_value);
> > +    }
> > +
> > +  return ret;
> > +}
> > +#endif
> > +weak_alias (__setitimer, setitimer)
>
> Tested-by: Lukasz Majewski <lukma@denx.de>
>
> (ARM + qemu)

Thanks!

>
> > diff --git a/sysdeps/unix/sysv/linux/tv32-compat.h
> > b/sysdeps/unix/sysv/linux/tv32-compat.h new file mode 100644
> > index 0000000000..4eb6f216ea
> > --- /dev/null
> > +++ b/sysdeps/unix/sysv/linux/tv32-compat.h
> > @@ -0,0 +1,35 @@
> > +/* Compatibility definitions for `struct timeval' with 32-bit time_t.
> > +   Copyright (C) 2020 Free Software Foundation, Inc.
> > +   This file is part of the GNU C Library.
> > +
> > +   The GNU C Library is free software; you can redistribute it and/or
> > +   modify it under the terms of the GNU Lesser General Public
> > +   License as published by the Free Software Foundation; either
> > +   version 2.1 of the License, or (at your option) any later version.
> > +
> > +   The GNU C Library is distributed in the hope that it will be
> > useful,
> > +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > +   Lesser General Public License for more details.
> > +
> > +   You should have received a copy of the GNU Lesser General Public
> > +   License along with the GNU C Library; if not, see
> > +   <http://www.gnu.org/licenses/>.  */
> > +
> > +#ifndef _TV32_COMPAT_H
> > +#define _TV32_COMPAT_H 1
> > +
> > +#include <features.h>
> > +
> > +#include <bits/types.h>
>
> I think that those two above headers are not necessary for this version
> of struct __itimerval32 definition.

I think you are right.

>
> > +#include <bits/types/time_t.h>
> > +#include <bits/types/struct_timeval.h>
>
> As fair as I can see - the below code is not using struct timeval
> anywhere, so this header is not necessary as well.

I think you are right here as well. I'm running the tests again if I
don't see any issues I will remove all of these.

>
> > +
> > +/* Structures containing 'struct timeval' with 32-bit time_t.  */
> > +struct __itimerval32
> > +{
> > +  struct __timeval32 it_interval;
> > +  struct __timeval32 it_value;
> > +};
> > +
> > +#endif /* tv32-compat.h */
>
>
> And just a side note - as we provide new getitimer/setitimer/getrusage
> implementations to /sysdeps/unix/sysv/linux/ , those entries in
> ./sysdeps/unix/syscalls.list could be removed (as we override them
> here).

Good point, I have removed those.

Thanks fro reviewing my series.

Alistair

>
> Anyway, this could be changed in a follow up patch and shall be
> regarded as a cleanup patch (no functional changes).
>
>
> Best regards,
>
> Lukasz Majewski
>
> --
>
> DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email: lukma@denx.de