From: Stas Sergeev <stsp@aknet.ru>
To: Petr Vandrovec <VANDROVE@vc.cvut.cz>
Cc: linux-kernel@vger.kernel.org
Subject: Re: ESP corruption bug - what CPUs are affected?
Date: Sat, 18 Sep 2004 20:45:33 +0400 [thread overview]
Message-ID: <414C662D.5090607@aknet.ru> (raw)
In-Reply-To: <3BFF2F87096@vcnet.vc.cvut.cz>
Hi Petr.
Petr Vandrovec wrote:
> natural solution seems to be to create complete 16bit CPL1
> environment, return to it, load ESP as you want, and then do IRET
> to return to CPL2 or CPL3. Fortunately V8086 mode is not affected,
> so there should be no problem with using CPL1 for this middle step.
> But of course it is not something you want to do on each return
> from interrupt handler... Well, or maybe you want...
Actually, this may indeed be what I want!
I think this can be implemented with the checks
that Denis Vlasenko suggests. Something like this
can be added to entry.S, right before the "iret":
---
if (!(old_EFLAGS & VM_MASK) && (descr_old_SS is 16bit one))
push_a_stack_frame_to_return_to_the_ring1_trampoline();
---
This way the overhead for the normal case would be
something about 4 asm insns (the check), and for the
dosemu case - who cares? (and probably also the wine
people will value that)
Does this look reasonable? If it does, I think I
should just start implementing that.
next prev parent reply other threads:[~2004-09-18 16:44 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-16 18:39 ESP corruption bug - what CPUs are affected? Petr Vandrovec
2004-09-17 18:12 ` Stas Sergeev
2004-09-18 16:45 ` Stas Sergeev [this message]
2004-09-18 16:59 ` Petr Vandrovec
2004-09-18 19:14 ` Stas Sergeev
2004-09-18 20:35 ` Petr Vandrovec
2004-09-22 18:49 ` Stas Sergeev
2004-09-22 19:19 ` Richard B. Johnson
2004-09-22 20:03 ` Stas Sergeev
2004-09-22 20:13 ` Richard B. Johnson
2004-09-28 15:43 ` Denis Vlasenko
2004-09-22 20:02 ` Petr Vandrovec
2004-09-23 4:09 ` Stas Sergeev
2004-09-23 17:08 ` Stas Sergeev
2004-09-23 18:06 ` Petr Vandrovec
2004-09-24 20:36 ` Stas Sergeev
2004-09-24 21:43 ` Petr Vandrovec
2004-09-25 8:04 ` Gabriel Paubert
2004-09-25 12:25 ` Stas Sergeev
2004-09-25 19:18 ` Gabriel Paubert
2004-09-25 20:40 ` Stas Sergeev
2004-09-25 23:42 ` Gabriel Paubert
2004-09-26 18:04 ` Stas Sergeev
2004-09-27 9:07 ` Gabriel Paubert
2004-09-30 15:11 ` Bill Davidsen
2004-10-06 16:18 ` ESP corruption bug - what CPUs are affected? (patch attempts) Stas Sergeev
-- strict thread matches above, loose matches on Subject: below --
2004-10-06 17:18 ESP corruption bug - what CPUs are affected? (patch att Petr Vandrovec
2004-10-11 18:32 ` ESP corruption bug - what CPUs are affected? Stas Sergeev
2004-09-16 17:49 Stas Sergeev
2004-09-16 19:03 ` Denis Vlasenko
2004-09-17 18:13 ` Stas Sergeev
2004-09-17 22:04 ` Denis Vlasenko
2004-09-18 10:58 ` Stas Sergeev
2004-09-18 13:08 ` Denis Vlasenko
2004-09-18 17:05 ` Stas Sergeev
[not found] ` <200409190108.45641.vda@port.imtp.ilyichevsk.odessa.ua>
2004-09-22 19:05 ` Stas Sergeev
2004-09-21 11:19 ` Pavel Machek
2004-09-21 11:43 ` Denis Vlasenko
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