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Re: [Qemu-devel] [PATCH] target-i386: fix addr16 prefix
From: |
Richard Henderson |
Subject: |
Re: [Qemu-devel] [PATCH] target-i386: fix addr16 prefix |
Date: |
Wed, 2 Mar 2016 10:27:05 -0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 03/02/2016 07:04 AM, Paolo Bonzini wrote:
> While ADDSEG will only be false in 16-bit mode for LEA, it can be
> false even in other cases when 16-bit addresses are obtained via
> the 67h prefix in 32-bit mode. In this case, gen_lea_v_seg forgets
> to add a nonzero FS or GS base if CS/DS/ES/SS are all zero. This
> case is pretty rare but happens when booting Windows 95/98, and
> this patch fixes it.
>
> The bug is visible since commit d6a291498, but it was introduced
> together with gen_lea_v_seg and it probably could be reproduced
> with a "addr16 gs movsb" instruction as early as in commit
> ca2f29f555805d07fb0b9ebfbbfc4e3656530977.
>
> Cc: address@hidden
> Reported-by: Hervé Poussineau <address@hidden>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> target-i386/translate.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
Reviewed-by: Richard Henderson <address@hidden>
It doesn't even seem to be uncommon inside the win98 kernel, once you start
looking for that addr16 gs pattern.
Thanks,
r~