linux-kernel - Re: [PATCH v2] ARM: Use udiv/sdiv for __aeabi

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Date:	Tue, 12 Nov 2013 14:40:01 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>
Cc:	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Måns Rullgård <mans@...sr.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	linux-kernel@...r.kernel.org,
	Christopher Covington <cov@...eaurora.org>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions

Nicolas Pitre <nicolas.pitre@...aro.org> writes:

> On Tue, 12 Nov 2013, Ben Dooks wrote:
>
>> Given these are single instructoins for ARM, is it possible we could
>> make a table of all the callers and fix them up when we initialise
>> as we do for the SMP/UP case and for page-offset?
>
> Not really.  Calls to those functions are generated by the compiler 
> implicitly when a divisor operand is used and therefore we cannot 
> annotate those calls.  We'd have to use special accessors everywhere to 
> replace the standard division operand (like we do for 64 by 32 bit 
> divisions) but I doubt that people would accept that.

It might be possible to extract this information from relocation tables.

-- 
Måns Rullgård
mans@...sr.com
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