Date: Sun, 6 Oct 2013 23:41:50 +0100
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Joel Fernandes <joelf@ti.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-omap@vger.kernel.org, Nicolas Pitre <nico@linaro.org>,
        Santosh Shilimkar <santosh.shilimkar@ti.com>,
        Jonathan Austin <jonathan.austin@arm.com>,
        =?iso-8859-1?Q?Andr=E9?= Hentschel <nerv@dawncrow.de>
Subject: Re: [RFC] ARM: kernel: irq: Simplify allocation of stack frame
Message-ID: <20131006224150.GA25647@n2100.arm.linux.org.uk>
References: <1381098649-21417-1-git-send-email-joelf@ti.com>
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On Sun, Oct 06, 2013 at 05:30:47PM -0500, Joel Fernandes wrote:
> On receiving IRQ exception in SVC mode, all the SVC mode registers are saved
> onto the stack very early on.
> 
> The stack frame allocation code for IRQ entry during SVC mode (svc_entry) is
> hard to read as 4-less is allocated initially only to be allocated later
> implicity using the mov r3, [sp, #-4]! instruction. We make code easier to read
> by allocating the 4 bytes on the stack frame in the beginning itself and remove
> all instances where 4 bytes is adjusted.

You omit to say that this results in saving one additional register
unnecessarily in the stmia.  We could use a stmib there instead which
would avoid that issue while keeping the rest of the change.
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