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From: Ziqiao Kong <ziqiaokong@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, ehabkost@redhat.com, rth@twiddle.net
Subject: Re: Bug: fstenv is wrongly implemented
Date: Fri, 2 Apr 2021 16:56:21 +0800	[thread overview]
Message-ID: <CAM0BWNCYXywdDdr+b6R1uFBNOKdaWnotaoy=W2DLjpx9eshcrQ@mail.gmail.com> (raw)
In-Reply-To: <7c63e938-2482-3150-7cfb-1459c132fda6@redhat.com>


Thanks for your reply.

I read the IA32 manual just now and indeed the patch is not correct.
Is there any related patch for this bug?


On Fri, Apr 2, 2021 at 4:45 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 02/04/21 10:29, Ziqiao Kong wrote:
> >
> > According to git blame, this bug is introduced about 13 years ago:
> > https://github.com/qemu/qemu/blame/633decd71119a4293e5e53e6059026c517a8bef0/target-i386/fpu_helper.c#L997.
> >
> > We also had a patch for this bug:
> > https://github.com/unicorn-engine/unicorn/commit/59b09a71bfc6fd8b95357944f6be9aa54f424421
> > which you may refer to. I can also help draft a patch if necessary.
> Hi!
> Unfortunately the patch is incorrect, because fpu_update_ip is called
> only at translation time and not at run-time.  If more than one x87
> instruction is present in the same translation block, or if a
> translation block has been compiled after the one that is executing,
> env->fpip will be incorrect.
> Thanks,
> Paolo

  reply	other threads:[~2021-04-02  8:57 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-02  8:29 Bug: fstenv is wrongly implemented Ziqiao Kong
2021-04-02  8:45 ` Paolo Bonzini
2021-04-02  8:56   ` Ziqiao Kong [this message]
2021-04-02  9:01     ` Paolo Bonzini
2021-04-02 10:48   ` Peter Maydell
2021-04-06 13:16     ` Ziqiao Kong

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