From: Lukasz Majewski <lukma@denx.de>
To: Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: Florian Weimer <fweimer@redhat.com>,
GNU C Library <libc-alpha@sourceware.org>,
Arnd Bergmann <arnd@arndb.de>,
Palmer Dabbelt <palmerdabbelt@google.com>,
Zong Li <zongbox@gmail.com>,
Alistair Francis <alistair.francis@wdc.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>,
"Maciej W. Rozycki" <macro@wdc.com>,
Alistair Francis <alistair23@gmail.com>,
arcml <linux-snps-arc@lists.infradead.org>,
Joseph Myers <joseph@codesourcery.com>
Subject: Re: switching ARC to 64-bit time_t (Re: [RFC v6 07/23] RISC-V: Use 64-bit time_t and off_t for RV32 and RV64)
Date: Thu, 20 Feb 2020 00:11:36 +0100 [thread overview]
Message-ID: <20200220001136.2f14236e@jawa> (raw)
In-Reply-To: <8a9784b3-fc52-adc3-4595-33142b059388@synopsys.com>
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Hi Vineet,
> Hi Alistair, Arnd
>
> On 2/14/20 2:39 PM, Alistair Francis wrote:
> > On Tue, Feb 11, 2020 at 5:30 PM Joseph Myers
> > <joseph@codesourcery.com> wrote:
> >> On Tue, 11 Feb 2020, Alistair Francis wrote:
> >>
> >>>>> diff --git a/sysdeps/unix/sysv/linux/riscv/bits/typesizes.h
> >>>>> b/sysdeps/unix/sysv/linux/riscv/bits/typesizes.h new file mode
> >>>>> 100644 index 0000000000..0da3bdeb5d
> >>>>> --- /dev/null
> >>>>> +++ b/sysdeps/unix/sysv/linux/riscv/bits/typesizes.h
> >>>> I was hoping newer arches could simply use the asm-generic one ?
> >>>>
> >>> We need to specify that RV32 uses a 64-bit time_t. The generic
> >>> ones don't do that for 32-bit arches.
> >> Since it seems we'd like future 32-bit ports of glibc to use
> >> 64-bit time and offsets, we should make that as easy as possible.
> >>
> >> That is, you need an RISC-V-specific bits/timesize.h. But you
> >> shouldn't need an RISC-V-specific bits/typesizes.h - rather, make
> >> the linux/generic one do the right thing for __TIME_T_TYPE based
> >> on bits/timesize.h. And have some other header that 32-bit
> >> linux/generic ports can use to say whether they use the 64-bit
> >> offset/stat/statfs interface, that bits/typesizes.h can use
> >> together with its existing __LP64__ check, and make the
> >> definitions of __OFF_T_TYPE etc. check that as well, and then you
> >> shouldn't need an RISC-V-specific bits/typesizes.h - the
> >> RISC-V-specific headers should be strictly minimal. (No
> >> architecture-specific bits/time64.h headers should be needed in
> >> any case.)
> > Ok, I have updated this. I'll send the patch once my "Always use
> > 32-bit time_t for certain syscalls" series is in (the headers are
> > changed in that series).
>
> I guess you haven't pushed changes yet, which don't make full copy of
> typesizes.h ?
>
> Anyhow I have a version based on your prior next branch where I
> switched ARC to 64-bit time_t - things work fine in general but I see
> some additional failures with the testsuite.
>
> Consider io/test-stat2.c which calls stat() and stat64() and compares
> the results: it now fails for ctime mismatch
>
> | ...
> | st_atime: [72] 644245094405576070 vs [72] 644245094405576070 OK
> | st_mtime: [88] 1975684956160000000 vs [88] 1975684956160000000 OK
> | st_ctime: [104] 0 vs [104] 2306351876938924035 FAIL
>
>
> In kernel asm-generic stat64 has 32-bit ctime (secs)
>
> struct stat64 {
> ...
> int st_atime; <-- offset 72
> unsigned int st_atime_nsec;
> int st_mtime; <-- offset *80*
> unsigned int st_mtime_nsec;
> int st_ctime; <-- offset 92
> unsigned int st_ctime_nsec;
> ...
> };
>
> In glibc, we have 64-bit time_t based timestamps so the structure
> diverges with kernel counterpart from time fields onwards.
>
> __extension__ typedef __int64_t __time_t; <-- ARC switched
> to 64-bit time_t
>
> struct timespec
> {
> __time_t tv_sec; <-- 8
> long int tv_nsec; <-- 4
> int: 32; <-- 4
> };
>
> struct stat64
> {
> ...
> struct timespec st_atim; <-- offset 72
> struct timespec st_mtim; <-- offset *88*
> struct timespec st_ctim; <-- offset 104
> int __glibc_reserved[2];
> };
>
> However glibc stat64()wrapper calls
> sysdeps/unix/sysv/linux/generic/wordsize-32/xstat64.c
>
> which for ARC is just doing a pass thru syscall because we do have
> __NR_fstatat64
> - hence the issues I see.
>
> It needs itemized copy
>
> __xstat64 (int vers, const char *name, struct stat64 *buf)
> {
> #ifdef __NR_fstatat64
> return INLINE_SYSCALL (fstatat64, 4, AT_FDCWD, name, buf,
> 0); #else
> ....
> int rc = INLINE_SYSCALL (statx, 5, AT_FDCWD, name,
> AT_NO_AUTOMOUNT, STATX_BASIC_STATS, &tmp);
> __cp_stat64_statx (buf, &tmp);
> #endif
>
> An the reason this all works on RISCV is that your kernel doesn't
> define __ARCH_WANT_STAT64 -> lacks __NR_statat64 and instead uses the
> statx call which does itemized copy and would work fine when copying
> from 32-bits time (in kernel) to 64-bits container in glibc. Is this
> is right understanding or am I missing something here.
>
> How do I build a latest RISCV 32-bit kernel + userland - do you have
> a buildroot branch somewhere that I can build / test with qemu ?
Maybe a bit off topic - there is such QEMU and Yocto/OE based test
sandbox for ARM32:
https://github.com/lmajewski/meta-y2038
(the README provides steps for setup).
>
> Thx,
> -Vineet
>
>
>
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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next prev parent reply other threads:[~2020-02-19 23:11 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1578824547.git.alistair.francis@wdc.com>
[not found] ` <4e95f95966d8d7c6a8339160dc62d81c1f6a1bfb.1578824547.git.alistair.francis@wdc.com>
2020-02-12 0:14 ` [RFC v6 07/23] RISC-V: Use 64-bit time_t and off_t for RV32 and RV64 Vineet Gupta
2020-02-12 0:14 ` Alistair Francis
2020-02-12 1:30 ` Joseph Myers
2020-02-14 22:39 ` Alistair Francis
2020-02-18 23:05 ` switching ARC to 64-bit time_t (Re: [RFC v6 07/23] RISC-V: Use 64-bit time_t and off_t for RV32 and RV64) Vineet Gupta
2020-02-18 23:13 ` Joseph Myers
2020-02-19 23:09 ` Lukasz Majewski
2020-02-19 23:11 ` Lukasz Majewski [this message]
2020-02-20 8:31 ` Arnd Bergmann
2020-02-20 9:37 ` Lukasz Majewski
2020-02-20 12:37 ` Arnd Bergmann
2020-02-20 13:14 ` Lukasz Majewski
2020-02-20 14:44 ` Arnd Bergmann
2020-02-20 15:42 ` Lukasz Majewski
2020-02-20 16:08 ` Arnd Bergmann
2020-02-20 16:31 ` Lukasz Majewski
2020-02-24 2:48 ` Viresh Kumar
2020-02-21 19:56 ` Alistair Francis
2020-02-22 8:42 ` Arnd Bergmann
2020-02-24 9:00 ` Lukasz Majewski
2020-02-24 9:46 ` Andreas Schwab
2020-02-24 10:14 ` Lukasz Majewski
2020-02-24 10:23 ` Andreas Schwab
2020-02-24 10:36 ` Lukasz Majewski
2020-02-24 10:42 ` Andreas Schwab
2020-02-24 11:13 ` Lukasz Majewski
2020-02-24 12:41 ` Lukasz Majewski
2020-02-25 0:03 ` Joseph Myers
2020-02-25 11:39 ` Lukasz Majewski
2020-02-25 14:36 ` Joseph Myers
2020-02-26 13:18 ` Lukasz Majewski
2020-02-26 14:48 ` Joseph Myers
2020-02-26 16:28 ` Lukasz Majewski
2020-02-25 9:03 ` Arnd Bergmann
2020-02-20 16:27 ` Helmut Grohne
2020-03-26 0:25 ` ARC rebootstrap prereq (was Re: switching ARC to 64-bit time_t ) Vineet Gupta
2020-03-26 5:54 ` Helmut Grohne
2020-03-26 11:51 ` Alexey Brodkin
2020-03-26 12:24 ` Helmut Grohne
2020-03-26 12:53 ` Alexey Brodkin
2020-03-26 14:28 ` Helmut Grohne
2020-03-26 19:04 ` Lennart Sorensen
2020-08-26 14:39 ` Vineet Gupta
2020-08-26 15:43 ` Helmut Grohne
2020-08-26 21:16 ` Aurelien Jarno
2021-02-24 20:17 ` Vineet Gupta
2021-02-26 9:47 ` Helmut Grohne
2021-02-26 15:58 ` Vineet Gupta
2021-08-21 17:36 ` Aurelien Jarno
2020-02-12 1:42 ` [RFC v6 07/23] RISC-V: Use 64-bit time_t and off_t for RV32 and RV64 Vineet Gupta
2020-02-12 12:58 ` Arnd Bergmann
2020-02-19 0:56 ` Vineet Gupta
2020-02-19 1:03 ` Alistair Francis
2020-02-19 1:31 ` Vineet Gupta
2020-02-19 8:30 ` Andreas Schwab
2020-02-19 18:42 ` Vineet Gupta
2020-02-19 23:18 ` Lukasz Majewski
2020-02-20 0:26 ` Vineet Gupta
2020-02-20 0:46 ` Joseph Myers
2020-02-20 8:24 ` Arnd Bergmann
2020-02-20 10:28 ` Lukasz Majewski
2020-02-20 14:14 ` Joseph Myers
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