From: Stefan Weil <sw@weilnetz.de>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Michael W. Bombardieri" <mb@ii.net>,
qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] qemu 1.6.1
Date: Sun, 27 Oct 2013 11:44:22 +0100 [thread overview]
Message-ID: <526CEE86.1020000@weilnetz.de> (raw)
In-Reply-To: <526CB88D.6030209@redhat.com>
Am 27.10.2013 07:54, schrieb Paolo Bonzini:
> Here is the code with annotations
>
> broken works
> -------------------------------------------------------------------------
> push %ebx
> sub $0x18,%esp sub $0x1c,%esp
> mov %ebx,0x14(%esp)
> mov %esi,0x18(%esp)
>
> movl $0x6d62a8,(%esp) movl $0x6d62a8,(%esp)
> mov 0x24(%esp),%ebx mov 0x24(%esp),%ebx ebx = to;
> call ___emutls_get_address call ___emutls_get_address eax = ¤t;
>
> mov (%eax),%esi esi = current;
>
> mov %ebx,(%eax) mov %ebx,(%eax) current = to;
>
> mov 0x28(%esp),%eax mov 0x28(%esp),%eax eax = action
> mov %eax,0x24(%ebx) mov %eax,0x24(%ebx) to->action = action
> mov 0x20(%ebx),%eax mov 0x20(%ebx),%eax eax = to->fiber
> mov %eax,(%esp) mov %eax,(%esp) "push" to->fiber
> call *0x835fc0 call *0x835fc0 SwitchToFiber(to->fiber)
> sub $0x4,%esp sub $0x4,%esp undo PASCAL calling convention
>
> ** mov 0x20(%esp),%eax eax = from
> mov 0x24(%eax),%eax mov 0x24(%esi),%eax eax = from->action
>
> mov 0x14(%esp),%ebx
> mov 0x18(%esp),%esi
> add $0x18,%esp add $0x1c,%esp
> pop %ebx
> ret ret
>
>
> I think the problem is that 0x20(%esp) gets somehow corrupted at the
> instruction I highlighted with **.
>
> The simplest fix then would be to add a barrier() before and after
> SwitchToFiber.
>
> Paolo
I tried adding two barrier() statements around SwitchToFiber().
That change did not result in different assembler code (=> unchanged
behaviour, QEMU still raises an assertion).
Stefan
next prev parent reply other threads:[~2013-10-27 10:44 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-23 7:39 [Qemu-devel] qemu 1.6.1 Michael W. Bombardieri
2013-10-23 9:00 ` Paolo Bonzini
2013-10-23 20:26 ` Stefan Weil
2013-10-24 10:38 ` Paolo Bonzini
2013-10-24 16:37 ` Stefan Weil
2013-10-24 21:47 ` Paolo Bonzini
2013-10-26 9:51 ` Stefan Weil
2013-10-27 6:54 ` Paolo Bonzini
2013-10-27 10:44 ` Stefan Weil [this message]
2013-10-27 15:38 ` Stefan Weil
2014-06-23 14:39 ` [Qemu-devel] broken win32 coroutines (was Re: qemu 1.6.1) Paolo Bonzini
2014-06-24 1:41 ` Michael W. Bombardieri
2014-06-24 5:22 ` Paolo Bonzini
2014-06-25 6:48 ` Michael W. Bombardieri
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