From: Arnd Bergmann <arnd@arndb.de>
To: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Cc: Florian Weimer <fweimer@redhat.com>,
Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org>,
Zack Weinberg <zack@owlfolio.org>
Subject: Re: [PATCH] linux: Use 'long int' for timespec tv_nsec on x32 (BZ #16437)
Date: Fri, 10 Dec 2021 12:23:21 +0100 [thread overview]
Message-ID: <CAK8P3a113BE-Dv+vF_1GVPC9HZ8eHFXeCD95Dng8x00pn02WtQ@mail.gmail.com> (raw)
In-Reply-To: <6ab62b15-6982-0786-3b61-b27c058c4475@linaro.org>
On Thu, Dec 9, 2021 at 8:35 PM Adhemerval Zanella via Libc-alpha
<libc-alpha@sourceware.org> wrote:
> On 09/12/2021 16:19, Florian Weimer wrote: * Adhemerval Zanella via Libc-alpha:
> > The change is also not entirely ABI-compatible because existing code on
> > x32 depends on the implementation clearing the upper 32 bits, and if new
> > code copies around structs, it won't necessary copy the zero bits.
>
> Afaiu the high-bits clearing is strictly necessary on kABI boundary for
> set functions. Some issues indeed might arise if user use timespec
> embedded in some function and mix objects built with different glibc
> version, but it is similar to 32-bit architectures with mixing time_t
> objects.
The kernel's 32-bit ABI ignores the upper 32 bits of tv_nsec for structures
passed from user space, but zeroes them when returning a timespec to user
space.
Only x32 is weird here, as it traditionally uses a mix of hte 32-bit user
space ABI and the 64-bit user space ABI.
Arnd
next prev parent reply other threads:[~2021-12-10 11:23 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-09 19:10 Adhemerval Zanella
2021-12-09 19:19 ` Florian Weimer
2021-12-09 19:35 ` Adhemerval Zanella
2021-12-10 11:23 ` Arnd Bergmann [this message]
2021-12-10 11:29 ` Florian Weimer
2021-12-10 12:48 ` Arnd Bergmann
2021-12-10 12:51 ` Florian Weimer
2021-12-10 13:11 ` Arnd Bergmann
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