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From: Dan Rue <dan.rue@linaro.org>
To: Shuah Khan <shuah@kernel.org>, Ingo Molnar <mingo@kernel.org>,
	Andy Lutomirski <luto@kernel.org>,
	Dmitry Safonov <dsafonov@virtuozzo.com>,
	Borislav Petkov <bp@alien8.de>,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: selftests/x86/fsgsbase_64 test problem
Date: Fri, 26 Jan 2018 09:36:31 -0600
Message-ID: <20180126153631.ha7yc33fj5uhitjo@xps> (raw)

We've noticed that fsgsbase_64 can fail intermittently with the
following error:

        [RUN]   ARCH_SET_GS(0x0) and clear gs, then schedule to 0x1
                Before schedule, set selector to 0x1
                other thread: ARCH_SET_GS(0x1) -- sel is 0x0
        [FAIL]  GS/BASE changed from 0x1/0x0 to 0x0/0x0

This can be reliably reproduced by running fsgsbase_64 in a loop. i.e.

    for i in $(seq 1 10000); do ./fsgsbase_64 || break; done

This problem isn't new - I've reproduced it on latest mainline and every
release going back to v4.12 (I did not try earlier). This was tested on
a Supermicro board with a Xeon E3-1220 as well as an Intel Nuc with an
i3-5010U.

Thanks,
Dan

             reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-26 15:36 Dan Rue [this message]
2018-01-26 16:22 ` Andy Lutomirski
2018-01-26 18:59   ` Andy Lutomirski
2018-01-26 19:46     ` Andy Lutomirski
2018-01-26 22:38       ` Andy Lutomirski
2018-01-26 22:42         ` Andy Lutomirski
2018-01-28 19:21           ` Andy Lutomirski
2018-01-29  9:13             ` H. Peter Anvin
2018-01-29 16:37               ` Andy Lutomirski
2018-01-29 18:12                 ` H. Peter Anvin
2018-01-29 18:26                   ` Andy Lutomirski
2018-01-29 18:30                     ` H. Peter Anvin
2018-02-27 22:59                       ` Dan Rue
2018-01-26 22:56         ` Borislav Petkov
2018-01-28 19:21           ` Andy Lutomirski
2018-01-26 22:51       ` H. Peter Anvin

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