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From: Jeff Dike <jdike@addtoit.com>
To: Eli Cooper <elicooper@gmx.com>
Cc: Richard Weinberger <richard@nod.at>,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] [PATCH] um: fix FPU register double-restore after sigreturn
Date: Fri, 18 Mar 2016 12:42:43 -0400	[thread overview]
Message-ID: <20160318164243.GA979@parts.user-mode-linux.org> (raw)
In-Reply-To: <56EC293B.8020407@gmx.com>

On Sat, Mar 19, 2016 at 12:13:47AM +0800, Eli Cooper wrote:
> I agree that we should keep userspace() minimal. So what in the first
> place is the FPU state save/restore code for? Or, what (except for
> sigreturn) could possibly mess the FPU state of the ptrace'd process
> without it?

My (vague) recollection was that with libc in there, I couldn't be
confident that it wouldn't unexpectedly use FP for something.  So,
saving and restoring FP state was a hedge against that happening.

				Jeff
-- 
Jeff Dike
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  reply	other threads:[~2016-03-18 17:01 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-16  1:25 [uml-devel] [PATCH] um: fix FPU register double-restore after sigreturn Eli Cooper
2016-03-17 22:21 ` Richard Weinberger
2016-03-18  1:41   ` Eli Cooper
2016-03-18  8:20     ` Richard Weinberger
2016-03-18 16:13       ` Eli Cooper
2016-03-18 16:42         ` Jeff Dike [this message]
2016-03-18 20:12           ` Richard Weinberger

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