From: stsp <stsp2@yandex.ru>
To: Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <seanjc@google.com>, kvm@vger.kernel.org
Subject: Re: exception vs SIGALRM race (with test-case now!)
Date: Thu, 24 Jun 2021 03:25:25 +0300 [thread overview]
Message-ID: <60ae8b9f-89af-e8b3-13c4-99ddea1ced90@yandex.ru> (raw)
In-Reply-To: <cbaa0b83-fc3a-5732-4246-386a0a0ff9b8@yandex.ru>
24.06.2021 03:11, stsp пишет:
> 24.06.2021 02:38, stsp пишет:
>> The test-case:
>> https://github.com/dosemu2/dosemu2/issues/1500#issuecomment-867215291
> URL was off 1 comment.
> The right one is:
> https://github.com/dosemu2/dosemu2/issues/1500#issuecomment-867214782
>
> Direct link to the test-case:
> https://github.com/dosemu2/dosemu2/files/6705274/a.exe.gz
What does this test-case do?
It provokes the PF by writing to
the NULL pointer. The PF handler
checks if PF is coming from the
right place, or from the nearby
IRQ8 timer handler. If PF is coming
from the very first instruction of
the timer handler, then we got
that nasty SIGALRM race and
KVM exited to user-space with
the pending PF exception.
How to replicate the buggy setup?
Just install dosemu2 on your
favourite distro using the pre-built packages:
https://github.com/dosemu2/dosemu2/blob/devel/README
How to run the test-case?
On the PC with Intel Core2 CPU,
run this command:
|dosemu -K ./a.exe -T -I 'ignore_djgpp_null_derefs off'|
|After a few seconds it will say
"Race DETECTED" and exit.
If it just keeps printing dots
forever, then your setup is not buggy,
press Ctrl-c to finish test.
|
next prev parent reply other threads:[~2021-06-24 0:25 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-12 22:49 guest/host mem out of sync on core2duo? stsp
2021-06-13 12:36 ` stsp
2021-06-14 17:06 ` Sean Christopherson
2021-06-14 17:32 ` stsp
2021-06-17 14:42 ` Sean Christopherson
2021-06-18 15:59 ` stsp
2021-06-18 21:07 ` Jim Mattson
2021-06-18 21:55 ` stsp
2021-06-18 22:06 ` Jim Mattson
2021-06-18 22:26 ` stsp
2021-06-18 22:32 ` Sean Christopherson
2021-06-19 0:11 ` stsp
2021-06-19 0:54 ` Sean Christopherson
2021-06-19 9:18 ` stsp
2021-06-21 2:34 ` exception vs SIGALRM race (was: Re: guest/host mem out of sync on core2duo?) stsp
2021-06-21 22:33 ` Jim Mattson
2021-06-21 23:32 ` stsp
2021-06-22 0:27 ` stsp
2021-06-28 21:47 ` Jim Mattson
2021-06-28 21:50 ` stsp
2021-06-28 22:00 ` stsp
2021-06-28 22:27 ` Jim Mattson
2021-07-06 16:28 ` Paolo Bonzini
2021-07-06 22:22 ` stsp
2021-07-06 23:41 ` Paolo Bonzini
2021-06-23 23:38 ` exception vs SIGALRM race (with test-case now!) stsp
2021-06-24 0:11 ` stsp
2021-06-24 0:25 ` stsp [this message]
2021-06-24 18:05 ` exception vs SIGALRM race on core2 CPUs (with qemu-based test-case this time!) stsp
2021-06-24 18:07 ` stsp
2021-06-25 23:35 ` exception vs SIGALRM race on core2 CPUs (with fix!) stsp
2021-06-26 0:15 ` Jim Mattson
2021-06-26 0:35 ` stsp
2021-06-26 21:50 ` stsp
2021-06-27 12:13 ` stsp
2021-06-26 14:03 ` exception vs SIGALRM race (another patch) stsp
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