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Re: The time(2) man page conflicts with glibc
- From: Andreas Schwab <schwab at suse dot de>
- To: Zack Weinberg <zackw at panix dot com>
- Cc: "H.J. Lu" <hjl dot tools at gmail dot com>, "Michael Kerrisk \(man-pages\)" <mtk dot manpages at gmail dot com>, libc-alpha <libc-alpha at sourceware dot org>, linux-man <linux-man at vger dot kernel dot org>
- Date: Tue, 15 Dec 2015 15:31:23 +0100
- Subject: Re: The time(2) man page conflicts with glibc
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOoJLk8VzyJKmkOvbmBxhCj4mVA2huYtHJsdxpatbkgJ1g at mail dot gmail dot com> <CAKCAbMj-X+wLKX3=MDm9z3L9zyikemxCNggu2bfw6=o6K5PGgg at mail dot gmail dot com>
Zack Weinberg <zackw@panix.com> writes:
> I did. The *actual system call* does indeed return -EFAULT when
> memory is invalid, which will be observed as 0xfffffffffffffff2 in the
> return value. However, the *vDSO shortcut* (which does not trap into
> the kernel) will just segfault the application. This is an observable
> ABI difference between statically and dynamically linked binaries.
Undefined behaviour can change any time in any way and is not part of
the ABI.
Andreas.
--
Andreas Schwab, SUSE Labs, schwab@suse.de
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"And now for something completely different."