linux-kernel - Re: [PATCH] ARM: avoid corrupts register in mcaro kputc kphex etc.

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Message-ID: <20140820100118.GH30401@n2100.arm.linux.org.uk>
Date:	Wed, 20 Aug 2014 11:01:18 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Wang Long <long.wanglong@...wei.com>
Cc:	nicolas.pitre@...aro.org, ben.dooks@...ethink.co.uk,
	taras.kondratiuk@...aro.org, heiko@...ech.de,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: avoid corrupts register in mcaro kputc kphex etc.

On Wed, Aug 20, 2014 at 05:50:02PM +0800, Wang Long wrote:
> when use macro 'kputc' kphex' to print the content of
> register r0-r3, they will corrupts these registers.
> 
> the same as the macro 'debug_reloc_start' and 'debug_reloc_end'.
> 
> so using 'push' when enter the macro and 'pop' when leave
> the macro to fix it.

NAK.  These are expected to corrupt r0-r3, and it is expected that
users of these macros save r0-r3 if they contain important values.
This is especially important as these get used in places where there
is no stack to save registers.

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