Message-ID: <4278455D.308@aknet.ru>
Date: Wed, 04 May 2005 07:45:33 +0400
From: Stas Sergeev <stsp@aknet.ru>
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To: Alexander Nyberg <alexn@telia.com>
CC: Andrew Morton <akpm@osdl.org>, torvalds@osdl.org,
       Mateusz Berezecki <mateuszb@gmail.com>, linux-kernel@vger.kernel.org,
       zwane@arm.linux.org.uk
Subject: Re: 2.6.12-rc3 OOPS  in vanilla source (once more)
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Hello.

Alexander Nyberg wrote:
> /From my reading a task that is scheduled away cannot have a partial/
> saved pt_regs. If this is correct then ptrace won't suffer from this
> problem
This is most likely correct, I
just wanted to be sure.

> I need to look at the partial stack issue closer, don't think I fully
> understand it yet.
When the IRQ/NMI interrupts the
ring0 code (kernel), since the
handler is also ring0, the interrupt
gate doesn't save the SS and ESP
when switching, so you miss the 8 bytes.
After looking at the code again I
don't think this can affect the
ptrace since the ptrace probably
never traces from an IRQ context
(I hope).
So I think it is safe to ignore my
previous comment. (if only perhaps
the "optimized" version of the patch
is to have a look)

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