Re: [RFC PATCH 1/6] ARM: mm: define LoUIS API for cache maintenance ops

[Dave Martin <dave.martin@linaro.org>]

On Thu, Sep 13, 2012 at 02:03:34PM +0100, Russell King - ARM Linux wrote:
> On Thu, Sep 13, 2012 at 12:39:49PM +0100, Dave Martin wrote:
> > We could introduce something like CONFIG_ARM_HAVE_CACHEFLUSH_LOUIS, and
> > do:
> > 
> > <asm/glue-cache.h>
> > #ifndef MULTI_CACHE
> > #ifdef CONFIG_HAVE_ARM_CACHEFLUSH_LOUIS
> > #define __cpuc_flush_kern_cache_louis __glue(_CACHE,_flush_kern_cache_louis)
> > #else
> > #define __cpuc_flush_kern_cache_louis __glue(_CACHE,_flush_kern_all)
> > #endif
> > #endif
> > 
> > <asm/cacheflush.h>
> > #ifdef MULTI_CACHE
> > #define flush_cache_louis()   cpu_cache.flush_kern_cache_louis()
> > #else
> > #define flush_cache_louis()   __cpuc_flush_kern_cache_louis()
> > #endif
> 
> No, this is stupidly complicated and is fragile.  Just alias the
> functions, like we do in cache-v4wt.S:
> 
> 	.globl	v4wt_dma_flush_range
> 	.equ	v4wt_dma_flush_range, v4wt_dma_inv_range
> 
> except, you'll need:
> 
> 	.globl	v4wt_flush_kern_cache_louis
> 	.equ	v4wt_flush_kern_cache_louis, v4wt_flush_kern_cache_all
> 
> You can do it automatically, using the attached sedscript and this bit
> of shell:
> 
> $ for f in $(grep -l define_cache_functions arch/arm/mm/*.S ); do
>     sed -if sedscript $f
>     git add $f
> done
> $ git commit -s
> 
> Do that first, and then go over those which you need to add a real
> flush_kern_cache_louis function to.

Sure, that works better.

I was trying to think of a more localised way to do it, but the result
was admittedly rather ugly (and not that localised once we select
HAVE_ARM_CACHEFLUSH_LOUIS all over the place).

Cheers
---Dave

> 1,/__INITDATA\|define struct cpu_cache_fns/ {
> 	/ENTRY.*flush_kern_cache_all/ {
>         	h
> 	        s/.*(\([^_]*\)_.*/\t.globl\t\1_flush_kern_cache_louis\n\t.equ\t\1_flush_kern_cache_louis, \1_flush_kern_cache_all\n/
>         	x
> 	}
> 	/__INITDATA\|define struct cpu_cache_fns/ {
>         	H
> 	        g
> 	}
> }