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Re: [PATCH] powerpc/32: fix csum_partial_copy_generic()

From Christophe Leroy <christophe.leroy@c-s.fr>
Newsgroups linux.kernel
Subject Re: [PATCH] powerpc/32: fix csum_partial_copy_generic()
Date 2016-08-01 15:50 +0200
Message-ID <s1lLr-702-15@gated-at.bofh.it> (permalink)
References <s1kZ3-6qC-15@gated-at.bofh.it> <s1lLr-702-17@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Le 01/08/2016 à 15:15, Segher Boessenkool a écrit :
> On Mon, Aug 01, 2016 at 02:56:05PM +0200, Christophe Leroy wrote:
>> --- a/arch/powerpc/lib/checksum_32.S
>> +++ b/arch/powerpc/lib/checksum_32.S
>> @@ -127,7 +127,8 @@ _GLOBAL(csum_partial_copy_generic)
>>  	stw	r7,12(r1)
>>  	stw	r8,8(r1)
>>
>> -	andi.	r0,r4,1			/* is destination address even ? */
>> +	rlwinm	r0,r4,3,0x8		/* is destination address even ? */
>> +	rlwnm	r6,r6,r0,0,31		/* swap bytes for odd destination */
>>  	cmplwi	cr7,r0,0
>>  	addic	r12,r6,0
>>  	addi	r6,r4,-4
>
> That does not "swap bytes"; it shifts the word up by 8 bits, instead.
> That may or may not do what is intended.
>

Indeed it does what is intended, similar to what is done at the end of 
the function:

	...
	beqlr+	cr7
	rlwinm	r3,r3,8,0,31	/* swap bytes for odd destination */
  	blr

Should I fix the (both) comment(s) ?

Christophe

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Thread

[PATCH] powerpc/32: fix csum_partial_copy_generic() Christophe Leroy <christophe.leroy@c-s.fr> - 2016-08-01 15:00 +0200
  Re: [PATCH] powerpc/32: fix csum_partial_copy_generic() Christophe Leroy <christophe.leroy@c-s.fr> - 2016-08-01 15:50 +0200
    Re: [PATCH] powerpc/32: fix csum_partial_copy_generic() Segher Boessenkool <segher@kernel.crashing.org> - 2016-08-01 16:40 +0200
  Re: [PATCH] powerpc/32: fix csum_partial_copy_generic() Segher Boessenkool <segher@kernel.crashing.org> - 2016-08-01 21:40 +0200

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