linux-kernel - Re: [RFC] x86, fpu: unify signal handling code paths for x86 and x86

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Date:	Thu, 14 Jun 2012 13:45:34 -0700
From:	Suresh Siddha <suresh.b.siddha@...el.com>
To:	Hans Rosenfeld <hans.rosenfeld@....com>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>, tglx@...utronix.de,
	robert.richter@....com, andreas.herrmann3@....com
Subject: Re: [RFC] x86, fpu: unify signal handling code paths for x86 and
 x86_64 kernels

On Thu, 2012-06-14 at 16:37 +0200, Hans Rosenfeld wrote:
> Thank you for working on this.
> 
> I didn't see anything obviously wrong in a quick review of this code,
> but this stuff is too complex for this to mean anything :)
> 
> I ran a quick test of your code. I found a signal frame corruption when
> running a 32bit test program on a 64bit kernel. I didn't try to find out
> why it failed, but I'll send you the test program in a private mail so
> you can look at it yourself.
> 

Ok. The problem was that I was using is_ia32_task() (which uses
TS_COMPAT) to check if the task is a compat task or not. And that flag
is not set during the signal delivery paths for the compat task.

I guess I should be using TIF_IA32 check instead. Using TIF_IA32 check
makes your test case run fine.

Will update it accordingly.

thanks,
suresh

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