From: Ziqiao Kong <email@example.com>
To: Peter Maydell <firstname.lastname@example.org>
Cc: Paolo Bonzini <email@example.com>,
Richard Henderson <firstname.lastname@example.org>,
QEMU Developers <email@example.com>,
Eduardo Habkost <firstname.lastname@example.org>
Subject: Re: Bug: fstenv is wrongly implemented
Date: Tue, 6 Apr 2021 21:16:23 +0800 [thread overview]
Message-ID: <CAM0BWNC2JrsUCjMBeTcH2tS06O5Pyk46sggMbr=DGxbsG=EKcQ@mail.gmail.com> (raw)
I checked that bug and list discussion and it indeed was the bug I
referred to. It seems that the patch should be quite straightforward
but no idea why the review of the patch was stalled at that time. I
would try to draft an updated patch these days.
On Fri, Apr 2, 2021 at 6:49 PM Peter Maydell <email@example.com> wrote:
> On Fri, 2 Apr 2021 at 09:47, Paolo Bonzini <firstname.lastname@example.org> 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.
> I think this is https://bugs.launchpad.net/qemu/+bug/661696 ?
> That had a patch attached which got some on-list discussion
> back in 2010:
> The review comments may be of help in coming up with an updated patch.
> -- PMM
prev parent reply other threads:[~2021-04-06 13:17 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
2021-04-02 9:01 ` Paolo Bonzini
2021-04-02 10:48 ` Peter Maydell
2021-04-06 13:16 ` Ziqiao Kong [this message]
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