Subject: Re: [RFC PATCH 1/2] powerpc: Remove duplicate cacheable_memcpy/memzero functions

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 16 Nov 2011 09:31:07 +1100

On Mon, 2011-11-14 at 21:32 -0500, Kyle Moffett wrote:
> These functions are only used from one place each.  If the cacheable_*
> versions really are more efficient, then those changes should be
> migrated into the common code instead.
> 
> NOTE: The old routines are just flat buggy on kernels that support
>       hardware with different cacheline sizes.
> 
> Signed-off-by: Kyle Moffett <[email-masked]>
> ---

Right, considering where those are used, I think we can safely remove
them. Thanks.

Ben.

>  arch/powerpc/include/asm/system.h    |    2 -
>  arch/powerpc/kernel/ppc_ksyms.c      |    2 -
>  arch/powerpc/lib/copy_32.S           |  127 ----------------------------------
>  arch/powerpc/mm/ppc_mmu_32.c         |    2 +-
>  drivers/net/ethernet/ibm/emac/core.c |   12 +---
>  5 files changed, 3 insertions(+), 142 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/system.h b/arch/powerpc/include/asm/system.h
> index e30a13d..25389d1 100644
> --- a/arch/powerpc/include/asm/system.h
> +++ b/arch/powerpc/include/asm/system.h
> @@ -189,8 +189,6 @@ static inline void flush_spe_to_thread(struct task_struct *t)
>  #endif
>  
>  extern int call_rtas(const char *, int, int, unsigned long *, ...);
> -extern void cacheable_memzero(void *p, unsigned int nb);
> -extern void *cacheable_memcpy(void *, const void *, unsigned int);
>  extern int do_page_fault(struct pt_regs *, unsigned long, unsigned long);
>  extern void bad_page_fault(struct pt_regs *, unsigned long, int);
>  extern int die(const char *, struct pt_regs *, long);
> diff --git a/arch/powerpc/kernel/ppc_ksyms.c b/arch/powerpc/kernel/ppc_ksyms.c
> index d3114a7..acba8ce 100644
> --- a/arch/powerpc/kernel/ppc_ksyms.c
> +++ b/arch/powerpc/kernel/ppc_ksyms.c
> @@ -159,8 +159,6 @@ EXPORT_SYMBOL(screen_info);
>  #ifdef CONFIG_PPC32
>  EXPORT_SYMBOL(timer_interrupt);
>  EXPORT_SYMBOL(tb_ticks_per_jiffy);
> -EXPORT_SYMBOL(cacheable_memcpy);
> -EXPORT_SYMBOL(cacheable_memzero);
>  #endif
>  
>  #ifdef CONFIG_PPC32
> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> index 55f19f9..6813f80 100644
> --- a/arch/powerpc/lib/copy_32.S
> +++ b/arch/powerpc/lib/copy_32.S
> @@ -69,54 +69,6 @@ CACHELINE_BYTES = L1_CACHE_BYTES
>  LG_CACHELINE_BYTES = L1_CACHE_SHIFT
>  CACHELINE_MASK = (L1_CACHE_BYTES-1)
>  
> -/*
> - * Use dcbz on the complete cache lines in the destination
> - * to set them to zero.  This requires that the destination
> - * area is cacheable.  -- paulus
> - */
> -_GLOBAL(cacheable_memzero)
> -	mr	r5,r4
> -	li	r4,0
> -	addi	r6,r3,-4
> -	cmplwi	0,r5,4
> -	blt	7f
> -	stwu	r4,4(r6)
> -	beqlr
> -	andi.	r0,r6,3
> -	add	r5,r0,r5
> -	subf	r6,r0,r6
> -	clrlwi	r7,r6,32-LG_CACHELINE_BYTES
> -	add	r8,r7,r5
> -	srwi	r9,r8,LG_CACHELINE_BYTES
> -	addic.	r9,r9,-1	/* total number of complete cachelines */
> -	ble	2f
> -	xori	r0,r7,CACHELINE_MASK & ~3
> -	srwi.	r0,r0,2
> -	beq	3f
> -	mtctr	r0
> -4:	stwu	r4,4(r6)
> -	bdnz	4b
> -3:	mtctr	r9
> -	li	r7,4
> -10:	dcbz	r7,r6
> -	addi	r6,r6,CACHELINE_BYTES
> -	bdnz	10b
> -	clrlwi	r5,r8,32-LG_CACHELINE_BYTES
> -	addi	r5,r5,4
> -2:	srwi	r0,r5,2
> -	mtctr	r0
> -	bdz	6f
> -1:	stwu	r4,4(r6)
> -	bdnz	1b
> -6:	andi.	r5,r5,3
> -7:	cmpwi	0,r5,0
> -	beqlr
> -	mtctr	r5
> -	addi	r6,r6,3
> -8:	stbu	r4,1(r6)
> -	bdnz	8b
> -	blr
> -
>  _GLOBAL(memset)
>  	rlwimi	r4,r4,8,16,23
>  	rlwimi	r4,r4,16,0,15
> @@ -142,85 +94,6 @@ _GLOBAL(memset)
>  	bdnz	8b
>  	blr
>  
> -/*
> - * This version uses dcbz on the complete cache lines in the
> - * destination area to reduce memory traffic.  This requires that
> - * the destination area is cacheable.
> - * We only use this version if the source and dest don't overlap.
> - * -- paulus.
> - */
> -_GLOBAL(cacheable_memcpy)
> -	add	r7,r3,r5		/* test if the src & dst overlap */
> -	add	r8,r4,r5
> -	cmplw	0,r4,r7
> -	cmplw	1,r3,r8
> -	crand	0,0,4			/* cr0.lt &= cr1.lt */
> -	blt	memcpy			/* if regions overlap */
> -
> -	addi	r4,r4,-4
> -	addi	r6,r3,-4
> -	neg	r0,r3
> -	andi.	r0,r0,CACHELINE_MASK	/* # bytes to start of cache line */
> -	beq	58f
> -
> -	cmplw	0,r5,r0			/* is this more than total to do? */
> -	blt	63f			/* if not much to do */
> -	andi.	r8,r0,3			/* get it word-aligned first */
> -	subf	r5,r0,r5
> -	mtctr	r8
> -	beq+	61f
> -70:	lbz	r9,4(r4)		/* do some bytes */
> -	stb	r9,4(r6)
> -	addi	r4,r4,1
> -	addi	r6,r6,1
> -	bdnz	70b
> -61:	srwi.	r0,r0,2
> -	mtctr	r0
> -	beq	58f
> -72:	lwzu	r9,4(r4)		/* do some words */
> -	stwu	r9,4(r6)
> -	bdnz	72b
> -
> -58:	srwi.	r0,r5,LG_CACHELINE_BYTES /* # complete cachelines */
> -	clrlwi	r5,r5,32-LG_CACHELINE_BYTES
> -	li	r11,4
> -	mtctr	r0
> -	beq	63f
> -53:
> -	dcbz	r11,r6
> -	COPY_16_BYTES
> -#if L1_CACHE_BYTES >= 32
> -	COPY_16_BYTES
> -#if L1_CACHE_BYTES >= 64
> -	COPY_16_BYTES
> -	COPY_16_BYTES
> -#if L1_CACHE_BYTES >= 128
> -	COPY_16_BYTES
> -	COPY_16_BYTES
> -	COPY_16_BYTES
> -	COPY_16_BYTES
> -#endif
> -#endif
> -#endif
> -	bdnz	53b
> -
> -63:	srwi.	r0,r5,2
> -	mtctr	r0
> -	beq	64f
> -30:	lwzu	r0,4(r4)
> -	stwu	r0,4(r6)
> -	bdnz	30b
> -
> -64:	andi.	r0,r5,3
> -	mtctr	r0
> -	beq+	65f
> -40:	lbz	r0,4(r4)
> -	stb	r0,4(r6)
> -	addi	r4,r4,1
> -	addi	r6,r6,1
> -	bdnz	40b
> -65:	blr
> -
>  _GLOBAL(memmove)
>  	cmplw	0,r3,r4
>  	bgt	backwards_memcpy
> diff --git a/arch/powerpc/mm/ppc_mmu_32.c b/arch/powerpc/mm/ppc_mmu_32.c
> index 11571e1..9f16b9f 100644
> --- a/arch/powerpc/mm/ppc_mmu_32.c
> +++ b/arch/powerpc/mm/ppc_mmu_32.c
> @@ -224,7 +224,7 @@ void __init MMU_init_hw(void)
>  	 */
>  	if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
>  	Hash = __va(memblock_alloc(Hash_size, Hash_size));
> -	cacheable_memzero(Hash, Hash_size);
> +	memset(Hash, 0, Hash_size);
>  	_SDR1 = __pa(Hash) | SDR1_LOW_BITS;
>  
>  	Hash_end = (struct hash_pte *) ((unsigned long)Hash + Hash_size);
> diff --git a/drivers/net/ethernet/ibm/emac/core.c b/drivers/net/ethernet/ibm/emac/core.c
> index ed79b2d..be214ad 100644
> --- a/drivers/net/ethernet/ibm/emac/core.c
> +++ b/drivers/net/ethernet/ibm/emac/core.c
> @@ -77,13 +77,6 @@ MODULE_AUTHOR
>      ("Eugene Surovegin <[email-masked]> or <[email-masked]>");
>  MODULE_LICENSE("GPL");
>  
> -/*
> - * PPC64 doesn't (yet) have a cacheable_memcpy
> - */
> -#ifdef CONFIG_PPC64
> -#define cacheable_memcpy(d,s,n) memcpy((d),(s),(n))
> -#endif
> -
>  /* minimum number of free TX descriptors required to wake up TX process */
>  #define EMAC_TX_WAKEUP_THRESH		(NUM_TX_BUFF / 4)
>  
> @@ -1637,7 +1630,7 @@ static inline int emac_rx_sg_append(struct emac_instance *dev, int slot)
>  			dev_kfree_skb(dev->rx_sg_skb);
>  			dev->rx_sg_skb = NULL;
>  		} else {
> -			cacheable_memcpy(skb_tail_pointer(dev->rx_sg_skb),
> +			memcpy(skb_tail_pointer(dev->rx_sg_skb),
>  					 dev->rx_skb[slot]->data, len);
>  			skb_put(dev->rx_sg_skb, len);
>  			emac_recycle_rx_skb(dev, slot, len);
> @@ -1694,8 +1687,7 @@ static int emac_poll_rx(void *param, int budget)
>  				goto oom;
>  
>  			skb_reserve(copy_skb, EMAC_RX_SKB_HEADROOM + 2);
> -			cacheable_memcpy(copy_skb->data - 2, skb->data - 2,
> -					 len + 2);
> +			memcpy(copy_skb->data - 2, skb->data - 2, len + 2);
>  			emac_recycle_rx_skb(dev, slot, len);
>  			skb = copy_skb;
>  		} else if (unlikely(emac_alloc_rx_skb(dev, slot, GFP_ATOMIC)))