From mboxrd@z Thu Jan  1 00:00:00 1970
From: will.deacon@arm.com (Will Deacon)
Date: Wed, 7 May 2014 11:17:09 +0100
Subject: [PATCH v2 2/2] arm64: enable context tracking
In-Reply-To: <1399419149-26685-3-git-send-email-larry.bassel@linaro.org>
References: <1399419149-26685-1-git-send-email-larry.bassel@linaro.org>
 <1399419149-26685-3-git-send-email-larry.bassel@linaro.org>
Message-ID: <20140507101709.GE18456@arm.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Wed, May 07, 2014 at 12:32:29AM +0100, Larry Bassel wrote:
> Make calls to ct_user_enter when the kernel is exited
> and ct_user_exit when the kernel is entered (in el0_da,
> el0_ia, el0_svc, el0_irq).

Why only these entry points? I can reschedule after any exception from EL0,
so I'd expect all exceptions from userspace to need annotating, no?

> These macros expand to function calls which will only work
> properly if el0_sync and related code has been rearranged
> (in a previous patch of this series).
> 
> In order to avoid saving registers, the slow syscall path
> is forced (as x86 does).

... and if you decide to handle undef exceptions, I think you'll need
the register saving too, in case the kernel needs to perform emulation.

Will