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Re: [Qemu-devel] qemu 1.6.1
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] qemu 1.6.1 |
Date: |
Sun, 27 Oct 2013 07:54:05 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 |
Il 26/10/2013 11:51, Stefan Weil ha scritto:
> Am 24.10.2013 23:47, schrieb Paolo Bonzini:
>> Il 24/10/2013 17:37, Stefan Weil ha scritto:
>>> Yes, that works, too. It also fixes the problem with the assertion
>>> (tested with Wine).
>>>
>>> No, we cannot remove from_, because the same interface is also used
>>> for Linux and other hosts which don't have a 'current' variable.
>>> Or we would have to call qemu_coroutine_self() to get the current
>>> coroutine.
>> Yes, I was thinking of using qemu_coroutine_self().
>>
>> By the way, can you post the two assembly language outputs for just
>>
>> - CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, from_);
>> + CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, current);
>>
>> which AIUI works and is enough to fix the bug?
>>
>> Paolo
>
> See disassembled code below. I removed compiler option -fstack-protector-all
> to simplify the assembler code and tested that the result was not affected
> by this removal.
>
> The C and assembler code from the test is also available at
> http://qemu.weilnetz.de/test/coroutine-win32/.
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
- [Qemu-devel] qemu 1.6.1, Michael W. Bombardieri, 2013/10/23
- Re: [Qemu-devel] qemu 1.6.1, Paolo Bonzini, 2013/10/23
- Re: [Qemu-devel] qemu 1.6.1, Stefan Weil, 2013/10/23
- Re: [Qemu-devel] qemu 1.6.1, Paolo Bonzini, 2013/10/24
- Re: [Qemu-devel] qemu 1.6.1, Stefan Weil, 2013/10/24
- Re: [Qemu-devel] qemu 1.6.1, Paolo Bonzini, 2013/10/24
- Re: [Qemu-devel] qemu 1.6.1, Stefan Weil, 2013/10/26
- Re: [Qemu-devel] qemu 1.6.1,
Paolo Bonzini <=
- Re: [Qemu-devel] qemu 1.6.1, Stefan Weil, 2013/10/27
- Re: [Qemu-devel] qemu 1.6.1, Stefan Weil, 2013/10/27