[PATCH 4/6] linux: Use 32-bit time_t for itimerval
Lukasz Majewski
lukma@denx.de
Mon Feb 10 23:19:00 GMT 2020
On Mon, 10 Feb 2020 09:56:40 -0800
Alistair Francis <alistair23@gmail.com> wrote:
> On Tue, Feb 4, 2020 at 6:49 AM Lukasz Majewski <lukma@denx.de> wrote:
> >
> > Hi Alistair,
> >
> > Maybe it would be good to rewrite the subject line to also reflect
> > the introduction of __[gs]etitimer64 ?
> >
> > > 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.
> > >
> > > This means that all 32-bit architectures with a 64-bit time_t
> > > will be able to use this generic implementation.
> > >
> > > This code is based on similar code in alpha, but adjusted to pass
> > > the 32-bit time_t to the kernel.
> > >
> > > We can't directly call the __getitimer/__setitimer functions as
> > > they expect a struct itimerval but we need to pass in a struct
> > > itimerval32.
> >
> > Please update this patch series to also include information about
> > build/run testing.
> >
> > For example:
> >
> > Build-tests:
> > ./src/scripts/build-many-glibcs.py glibcs
>
> Sorry Lukasz, I somehow lost your response in my v2. I have updated my
> v3 with your comments here.
Ok, I'm looking forward for v3 then :-).
Thanks for your patches.
>
> >
> >
> > > ---
> > > include/time.h | 12 +++
> > > .../linux/generic/wordsize-32/getitimer.c | 54 +++++++++++++
> > > .../linux/generic/wordsize-32/setitimer.c | 77
> > > +++++++++++++++++++ .../linux/generic/wordsize-32/tv32-compat.h
> > > | 35 +++++++++ 4 files changed, 178 insertions(+)
> > > create mode 100644
> > > sysdeps/unix/sysv/linux/generic/wordsize-32/getitimer.c create
> > > mode
> >
> > The same issue as pointed out in patch 6/6. The path
> > sysdeps/unix/sysv/linux/generic/wordsize-32 is NOT searched by ARMv7
> > (ARM32) for files to be built.
> >
> > I've removed getitimer, getrusage and setitimer from
> > ./sysdeps/unix/syscalls.list, so they are NOT auto generated
> > wrappers anymore, but this doesn't help.
> >
> > It seems like for RV32 some extra paths are added...
> >
> > I've dug to the @sysnames@ variable set in configure in the source
> > of glibc. I'm wondering how RV32 modifies it (and how it differs
> > from ARM32)?
>
> This has been addressed in v2.
>
> >
> >
> > > 100644 sysdeps/unix/sysv/linux/generic/wordsize-32/setitimer.c
> > > create mode 100644
> > > sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h
> > >
> > > diff --git a/include/time.h b/include/time.h
> > > index 898ff0fb2d..e1d80b4190 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>
> > >
> > > @@ -118,6 +119,17 @@ struct __itimerval64
> > > };
> > > #endif
> > >
> > > +#if __TIMESIZE == 64
> > > +# define __getitimer64 __getitimer
> > > +# define __setitimer64 __setitimer
> > > +#else
> > > +extern int __getitimer64 (enum __itimer_which __which,
> > > + struct __itimerval64 *__value);
> >
> > Please add here:
> > libc_hidden_proto (__getitimer64)
>
> Fixed in v3
>
> >
> > > +extern int __setitimer64 (enum __itimer_which __which,
> > > + const struct __itimerval64 *__restrict
> > > __new,
> > > + struct __itimerval64 *__restrict
> > > __old);
> >
> > Please add here:
> > libc_hidden_proto (__setitimer64)
>
> Fixed in v3
>
> >
> > > +#endif
> > > +
> > > #if __TIMESIZE == 64
> > > # define __ctime64 ctime
> > > #else
> > > diff --git
> > > a/sysdeps/unix/sysv/linux/generic/wordsize-32/getitimer.c
> > > b/sysdeps/unix/sysv/linux/generic/wordsize-32/getitimer.c new
> > > file mode 100644 index 0000000000..28a3e31126 --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/generic/wordsize-32/getitimer.c
> > > @@ -0,0 +1,54 @@
> > > +/* 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 <sysdep.h>
> > > +#include <tv32-compat.h>
> > > +
> > > +int
> > > +__getitimer64 (__itimer_which_t which, struct __itimerval64
> > > *curr_value) +{
> > > + 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;
> > > +}
> > > +
> > > +
> > > +#if __TIMESIZE != 64
> >
> > Please add here:
> > libc_hidden_def (__gettimer64)
>
> Fixed in v3
>
> >
> > Rationale:
> >
> > Before we introduce the Y2038 support (with -D_TIME_BITS=64) the
> > __gettimer64 shall be hidden (to avoid resolving it via PLT).
> >
> > > +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);
> > > +}
> >
> > Ok. As we expect 32 bit values - there is no need for checking (and
> > 64 <-> 32 conversions will be OK).
> >
> > > +#endif
> > > +weak_alias (__getitimer, getitimer)
> > > diff --git
> > > a/sysdeps/unix/sysv/linux/generic/wordsize-32/setitimer.c
> > > b/sysdeps/unix/sysv/linux/generic/wordsize-32/setitimer.c new
> > > file mode 100644 index 0000000000..fabc7f2c0c --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/generic/wordsize-32/setitimer.c
> > > @@ -0,0 +1,77 @@
> > > +/* 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 <sysdep.h>
> > > +#include <tv32-compat.h>
> > > +
> > > +int
> > > +__setitimer64 (__itimer_which_t which,
> > > + const struct __itimerval64 *restrict new_value,
> > > + struct __itimerval64 *restrict old_value)
> > > +{
> > > + struct __itimerval32 new_value_32;
> > > + new_value_32.it_interval
> > > + = valid_timeval64_to_timeval32 (new_value->it_interval);
> > > + 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); +
> >
> > The above code is correct of course.
> >
> > However, I've used another approach for timerfd_settime (IMHO a bit
> > more concise):
> > https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/timerfd_settime.c;h=164b4e860acb6a365a3890f30e2eac364a518c22;hb=eae22432723b877354291aca4dbbfde5891dad59#l49
> >
> > > + 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;
> > > +}
> > > +
> > > +#if __TIMESIZE != 64
> >
> > Please add here:
> > libc_hidden_def (__settimer64)
>
> Fixed in v3
>
> >
> > > +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, &old64);
> >
> > I think that here we shall also consider the NULL pointer for
> > old_value (as stated in
> > http://man7.org/linux/man-pages/man2/setitimer.2.html)
> >
> > ret = __setitimer64 (which, &new64, old_value ? &old64 : NULL);
> >
> > > +
> > > + if (ret != 0)
> > > + return ret;
> > > +
> > > + old_value->it_interval
> > > + = valid_timeval64_to_timeval (old64.it_interval);
> > > + old_value->it_value
> > > + = valid_timeval64_to_timeval (old64.it_value);
> > > +
> >
> > Maybe it would be better to change this code to:
> >
> > 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
>
> Fixed in v3
>
> >
> > Please find the timerfd_settime as a reference:
> > https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/timerfd_settime.c;h=164b4e860acb6a365a3890f30e2eac364a518c22;hb=eae22432723b877354291aca4dbbfde5891dad59#l77
> >
> > > + return ret;
> > > +}
> > > +#endif
> > > +weak_alias (__setitimer, setitimer)
> > > diff --git
> > > a/sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h
> > > b/sysdeps/unix/sysv/linux/generic/wordsize-32/tv32-compat.h new
> > > file mode 100644 index 0000000000..4eb6f216ea --- /dev/null
> > > +++ b/sysdeps/unix/sysv/linux/generic/wordsize-32/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>
> > > +#include <bits/types/time_t.h>
> > > +#include <bits/types/struct_timeval.h>
> > > +
> > > +/* Structures containing 'struct timeval' with 32-bit time_t. */
> > > +struct __itimerval32
> > > +{
> > > + struct __timeval32 it_interval;
> > > + struct __timeval32 it_value;
> > > +};
> >
> > I do guess that here (with the introduction of tv32-compat.h) we do
> > follow what is done for alpha port?
>
> Alpha always uses a 32-bit value, while in the generic case we use a
> long (so the wordsize).
>
> Alistair
>
> >
> > > +
> > > +#endif /* tv32-compat.h */
> >
> >
> >
> >
> > 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
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
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