linux-kernel - Re: [PATCH] ARM: alignment: Use is_wide_instruction() to check wide instruction

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Message-ID: <20150413150757.GB15504@e103592.cambridge.arm.com>
Date:	Mon, 13 Apr 2015 16:07:57 +0100
From:	Dave Martin <Dave.Martin@....com>
To:	Yingjoe Chen <yingjoe.chen@...iatek.com>
Cc:	linux-arm-kernel@...ts.infradead.org,
	Catalin Marinas <catalin.marinas@....com>,
	Russell King <linux@....linux.org.uk>,
	linux-kernel@...r.kernel.org, srv_heupstream@...iatek.com
Subject: Re: [PATCH] ARM: alignment: Use is_wide_instruction() to check wide
 instruction

On Mon, Apr 13, 2015 at 10:47:24PM +0800, Yingjoe Chen wrote:
> On Mon, 2015-04-13 at 13:48 +0100, Dave Martin wrote:
> > On Fri, Apr 10, 2015 at 10:05:41PM +0800, Yingjoe Chen wrote:
> > > 
> > > I first notice the comment is incorrect, then I realize there's another
> > > macro which do exactly the same thing.
> > > Tested with hand written userspace program with a few wide instructions
> > > to make sure this still work as expect.
> > > 
> > > 8<-------------------------------------------------
> > > do_alignment() is using locally added IS_T32() macro to check if an
> > > instruction is a Thumb-2 32 bit instruction. The macro
> > > is_wide_instruction() is doing the same thing, with slightly faster
> > > implementation.
> > > Change to use is_wide_instruction() in do_alignment() and remove
> > > IS_T32().
> > 
> > Reviewed-by: Dave Martin <Dave.Martin@....com>
> > 
> > The existing code is correct, but the comment is indeed wrong.
> > Consolidating this with one of the other existing macros makes sense.
> > 
> > 
> > !__opcode_is_thumb16() could also be used here (or is_wide_instruction()
> > redefined in terms of it), but that's not essential.
> 
> Hi Dave,
> 
> Thanks for your review.
> 
> I did notice there are __opcode_is_thumb16/32. They need to handle
> 32bits instruction instead of 16bits only for is_wide_instruction, so I
> think using same implementation for them is a different story.
> 
> Joe.C

No worries.  It can be tidied up some more later if someone finds a good
reason for it.

Cheers
---Dave

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