From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Mon, 14 Aug 2017 12:18:59 -0400 (EDT)
From: Nicolas Pitre <nicolas.pitre@linaro.org>
In-Reply-To: <20170814155002.GV6321@e103592.cambridge.arm.com>
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References: <20170814125411.22604-1-ard.biesheuvel@linaro.org> <20170814125411.22604-3-ard.biesheuvel@linaro.org> <20170814152950.GT6321@e103592.cambridge.arm.com> <CAKv+Gu87G93X36TdAEiMC46Uz_PqXEi_4LSftnUdkQ8HRCxWiA@mail.gmail.com>
 <20170814155002.GV6321@e103592.cambridge.arm.com>
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Subject: [kernel-hardening] Re: [PATCH 02/30] ARM: assembler: introduce adr_l, ldr_l and str_l
 macros
To: Dave Martin <Dave.Martin@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>, Mark Rutland <mark.rutland@arm.com>, Kees Cook <keescook@chromium.org>, Arnd Bergmann <arnd@arndb.de>, Marc Zyngier <marc.zyngier@arm.com>, Kernel Hardening <kernel-hardening@lists.openwall.com>, Russell King <linux@armlinux.org.uk>, Tony Lindgren <tony@atomide.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Thomas Garnier <thgarnie@google.com>, Matt Fleming <matt@codeblueprint.co.uk>
List-ID: <kernel-hardening.lists.openwall.com>

On Mon, 14 Aug 2017, Dave Martin wrote:

> On Mon, Aug 14, 2017 at 04:38:02PM +0100, Ard Biesheuvel wrote:
> > That's a trick, actually, which I failed to add a comment for.

Shame shame shame !

> > We use .arm sections in the thumb2 kernel, and using these macros
> > there would result in the wrong offset to be used. Adding the .w
> > suffix forces an error in the assembler which even results in a fairly
> > meaningful error message complaining about using .w in ARM code.
> 
> Ewww... I think it'd be best to add a comment explaining that.

Absolutely!


Nicolas