[PATCH] XOR implementation for ARMv8

[Will Deacon]

On Tue, Jun 30, 2015 at 05:01:17PM +0100, Will Deacon wrote:
> On Wed, Jun 24, 2015 at 08:00:30AM +0100, 刘晓东 wrote:
> > diff -pruN -X dontdiff linux-4.0.5-orig/arch/arm64/lib/xor.S linux-4.0.5-mod/arch/arm64/lib/xor.S
> > --- linux-4.0.5-orig/arch/arm64/lib/xor.S       1970-01-01 08:00:00.000000000 +0800
> > +++ linux-4.0.5-mod/arch/arm64/lib/xor.S        2015-06-24 09:25:49.969256540 +0800
> > @@ -0,0 +1,228 @@
> > +/*
> > + * arch/arm64/lib/xor.S
> > + *
> > + * Copyright (C) Xiaodong Liu <liuxiaodong at nudt.edu.cn>, Changsha, P.R. China
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + */
> > +
> > +#include <linux/linkage.h>
> > +#include <asm/assembler.h>
> > +.macro xor_vectorregs16
> > +    eor v24.16b, v24.16b, v16.16b
> > +    eor v25.16b, v25.16b, v17.16b
> > +    eor v26.16b, v26.16b, v18.16b
> > +    eor v27.16b, v27.16b, v19.16b
> > +    eor v28.16b, v28.16b, v20.16b
> > +    eor v29.16b, v29.16b, v21.16b
> > +    eor v30.16b, v30.16b, v22.16b
> > +    eor v31.16b, v31.16b, v23.16b
> > +.endm
> > +
> > +.align 4
> > +
> > +/*
> > + * void xor_arm64ldpregs16_2(unsigned long size, unsigned long * dst, unsigned long *src);
> > + *
> > + * Parameters:
> > + *     x0 - size
> > + *     x1 - dst
> > + *     x2 - src
> > + */
> > +ENTRY(xor_arm64ldpregs16_2)
> > +
> > +    lsr x0, x0, #10
> > +
> > +.p2align 4
> > +Loop23:
> > +    ldp q16, q17, [x2], #32
> > +    ldp q18, q19, [x2], #32
> > +    ldp q20, q21, [x2], #32
> > +    ldp q22, q23, [x2], #32
> 
> Have you tried using immediate offsets instead of post-index addressing?
> E.g.
> 
> 	ldp q16, q17, [x2]
> 	ldp q18, q19, [x2, #32], #32
> 	ldp q20, q21, [x2, #64], #32

Without the post-index offsets, of course ;)

Will