linux-kernel - Re: [RFC] ARM: kernel: irq: Simplify allocation of stack frame

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sun, 6 Oct 2013 23:41:50 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Joel Fernandes <joelf@...com>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, Nicolas Pitre <nico@...aro.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Jonathan Austin <jonathan.austin@....com>,
	André Hentschel <nerv@...ncrow.de>
Subject: Re: [RFC] ARM: kernel: irq: Simplify allocation of stack frame

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/