From: Andi Kleen <ak@suse.de>
To: Kevin Lawton <kevinlawton2001@yahoo.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Possible bug in arch/i386/kernel/process.c for reloading of debug registers (DRx)?
Date: 04 Feb 2003 01:39:43 +0100 [thread overview]
Message-ID: <p7365s0ri9c.fsf@oldwotan.suse.de> (raw)
In-Reply-To: Kevin Lawton's message of "4 Feb 2003 01:19:16 +0100"
Kevin Lawton <kevinlawton2001@yahoo.com> writes:
> I was scanning through the source and noticed the lines below.
> Should the code below, be reloading at least the local bits of
> DR7 if the current DR7 value != 0? From a quick glance, it
> looks like only if the next task's DR7 value is non-zero,
> that DR7 is reloaded. I'm wondering if this would leave
> a new task to receive "local" debug events for the previous
> task if prev->DR7!=0 && next->DR7==0.
The do_debug trap handler handles that. It checks that
the debug event is set in the current process before doing anything
and if they weren't they are clared.
So yes they leak, but only once and the user should never notice.
-Andi
next parent reply other threads:[~2003-02-04 0:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20030203235140.10443.qmail@web80304.mail.yahoo.com.suse.lists.linux.kernel>
2003-02-04 0:39 ` Andi Kleen [this message]
2003-02-07 16:33 ` Pavel Machek
2003-02-08 17:22 ` Andi Kleen
2003-02-08 19:31 ` Jamie Lokier
2003-02-09 0:56 ` Andi Kleen
2003-02-09 6:15 ` [PATCH] Optimisation and CONFIG_PREEMPT fix of reloading of debug registers Jamie Lokier
2003-02-03 23:51 Possible bug in arch/i386/kernel/process.c for reloading of debug registers (DRx)? Kevin Lawton
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