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Commit 7aef4136 authored by Christophe Leroy's avatar Christophe Leroy Committed by Scott Wood
Browse files

powerpc32: rewrite csum_partial_copy_generic() based on copy_tofrom_user() 



csum_partial_copy_generic() does the same as copy_tofrom_user and also
calculates the checksum during the copy. Unlike copy_tofrom_user(),
the existing version of csum_partial_copy_generic() doesn't take
benefit of the cache.

This patch is a rewrite of csum_partial_copy_generic() based on
copy_tofrom_user().
The previous version of csum_partial_copy_generic() was handling
errors. Now we have the checksum wrapper functions to handle the error
case like in powerpc64 so we can make the error case simple:
just return -EFAULT.
copy_tofrom_user() only has r12 available => we use it for the
checksum r7 and r8 which contains pointers to error feedback are used,
so we stack them.

On a TCP benchmark using socklib on the loopback interface on which
checksum offload and scatter/gather have been deactivated, we get
about 20% performance increase.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarScott Wood <oss@buserror.net>
parent 37e08cad

arch/powerpc/lib/checksum_32.S

+209 −111
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 


#include <linux/sys.h>

#include <asm/processor.h>

#include <asm/cache.h>

#include <asm/errno.h>

#include <asm/ppc_asm.h>
@@ -66,123 +67,220 @@ _GLOBAL(csum_partial) 
 *

 * csum_partial_copy_generic(src, dst, len, sum, src_err, dst_err)

 */

#define CSUM_COPY_16_BYTES_WITHEX(n)	\

8 ## n ## 0:			\

	lwz	r7,4(r4);	\

8 ## n ## 1:			\

	lwz	r8,8(r4);	\

8 ## n ## 2:			\

	lwz	r9,12(r4);	\

8 ## n ## 3:			\

	lwzu	r10,16(r4);	\

8 ## n ## 4:			\

	stw	r7,4(r6);	\

	adde	r12,r12,r7;	\

8 ## n ## 5:			\

	stw	r8,8(r6);	\

	adde	r12,r12,r8;	\

8 ## n ## 6:			\

	stw	r9,12(r6);	\

	adde	r12,r12,r9;	\

8 ## n ## 7:			\

	stwu	r10,16(r6);	\

	adde	r12,r12,r10



#define CSUM_COPY_16_BYTES_EXCODE(n)		\

.section __ex_table,"a";		\

	.align	2;			\

	.long	8 ## n ## 0b,src_error;	\

	.long	8 ## n ## 1b,src_error;	\

	.long	8 ## n ## 2b,src_error;	\

	.long	8 ## n ## 3b,src_error;	\

	.long	8 ## n ## 4b,dst_error;	\

	.long	8 ## n ## 5b,dst_error;	\

	.long	8 ## n ## 6b,dst_error;	\

	.long	8 ## n ## 7b,dst_error;	\

	.text



	.text

	.stabs	"arch/powerpc/lib/",N_SO,0,0,0f

	.stabs	"checksum_32.S",N_SO,0,0,0f

0:



CACHELINE_BYTES = L1_CACHE_BYTES

LG_CACHELINE_BYTES = L1_CACHE_SHIFT

CACHELINE_MASK = (L1_CACHE_BYTES-1)



_GLOBAL(csum_partial_copy_generic)

	addic	r0,r6,0

	subi	r3,r3,4

	subi	r4,r4,4

	srwi.	r6,r5,2

	beq	3f		/* if we're doing < 4 bytes */

	andi.	r9,r4,2		/* Align dst to longword boundary */

	beq+	1f

81:	lhz	r6,4(r3)	/* do 2 bytes to get aligned */

	addi	r3,r3,2

	subi	r5,r5,2

91:	sth	r6,4(r4)

	addi	r4,r4,2

	addc	r0,r0,r6

	srwi.	r6,r5,2		/* # words to do */

	beq	3f

1:	srwi.	r6,r5,4		/* # groups of 4 words to do */

	beq	10f

	mtctr	r6

71:	lwz	r6,4(r3)

72:	lwz	r9,8(r3)

73:	lwz	r10,12(r3)

74:	lwzu	r11,16(r3)

	adde	r0,r0,r6

75:	stw	r6,4(r4)

	adde	r0,r0,r9

76:	stw	r9,8(r4)

	adde	r0,r0,r10

77:	stw	r10,12(r4)

	adde	r0,r0,r11

78:	stwu	r11,16(r4)

	bdnz	71b

10:	rlwinm.	r6,r5,30,30,31	/* # words left to do */

	beq	13f

	mtctr	r6

82:	lwzu	r9,4(r3)

92:	stwu	r9,4(r4)

	adde	r0,r0,r9

	bdnz	82b

13:	andi.	r5,r5,3

3:	cmpwi	0,r5,2

	blt+	4f

83:	lhz	r6,4(r3)

	addi	r3,r3,2

	subi	r5,r5,2

93:	sth	r6,4(r4)

	stwu	r1,-16(r1)

	stw	r7,12(r1)

	stw	r8,8(r1)



	andi.	r0,r4,1			/* is destination address even ? */

	cmplwi	cr7,r0,0

	addic	r12,r6,0

	addi	r6,r4,-4

	neg	r0,r4

	addi	r4,r3,-4

	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 */

	mtctr	r8

	beq+	61f

	li	r3,0

70:	lbz	r9,4(r4)		/* do some bytes */

	addi	r4,r4,1

	slwi	r3,r3,8

	rlwimi	r3,r9,0,24,31

71:	stb	r9,4(r6)

	addi	r6,r6,1

	bdnz	70b

	adde	r12,r12,r3

61:	subf	r5,r0,r5

	srwi.	r0,r0,2

	mtctr	r0

	beq	58f

72:	lwzu	r9,4(r4)		/* do some words */

	adde	r12,r12,r9

73:	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

	beq	63f



	/* Here we decide how far ahead to prefetch the source */

	li	r3,4

	cmpwi	r0,1

	li	r7,0

	ble	114f

	li	r7,1

#if MAX_COPY_PREFETCH > 1

	/* Heuristically, for large transfers we prefetch

	   MAX_COPY_PREFETCH cachelines ahead.  For small transfers

	   we prefetch 1 cacheline ahead. */

	cmpwi	r0,MAX_COPY_PREFETCH

	ble	112f

	li	r7,MAX_COPY_PREFETCH

112:	mtctr	r7

111:	dcbt	r3,r4

	addi	r3,r3,CACHELINE_BYTES

	bdnz	111b

#else

	dcbt	r3,r4

	addi	r3,r3,CACHELINE_BYTES

#endif /* MAX_COPY_PREFETCH > 1 */



114:	subf	r8,r7,r0

	mr	r0,r7

	mtctr	r8



53:	dcbt	r3,r4

54:	dcbz	r11,r6

/* the main body of the cacheline loop */

	CSUM_COPY_16_BYTES_WITHEX(0)

#if L1_CACHE_BYTES >= 32

	CSUM_COPY_16_BYTES_WITHEX(1)

#if L1_CACHE_BYTES >= 64

	CSUM_COPY_16_BYTES_WITHEX(2)

	CSUM_COPY_16_BYTES_WITHEX(3)

#if L1_CACHE_BYTES >= 128

	CSUM_COPY_16_BYTES_WITHEX(4)

	CSUM_COPY_16_BYTES_WITHEX(5)

	CSUM_COPY_16_BYTES_WITHEX(6)

	CSUM_COPY_16_BYTES_WITHEX(7)

#endif

#endif

#endif

	bdnz	53b

	cmpwi	r0,0

	li	r3,4

	li	r7,0

	bne	114b



63:	srwi.	r0,r5,2

	mtctr	r0

	beq	64f

30:	lwzu	r0,4(r4)

	adde	r12,r12,r0

31:	stwu	r0,4(r6)

	bdnz	30b



64:	andi.	r0,r5,2

	beq+	65f

40:	lhz	r0,4(r4)

	addi	r4,r4,2

	adde	r0,r0,r6

4:	cmpwi	0,r5,1

	bne+	5f

84:	lbz	r6,4(r3)

94:	stb	r6,4(r4)

	slwi	r6,r6,8		/* Upper byte of word */

	adde	r0,r0,r6

5:	addze	r3,r0		/* add in final carry */

41:	sth	r0,4(r6)

	adde	r12,r12,r0

	addi	r6,r6,2

65:	andi.	r0,r5,1

	beq+	66f

50:	lbz	r0,4(r4)

51:	stb	r0,4(r6)

	slwi	r0,r0,8

	adde	r12,r12,r0

66:	addze	r3,r12

	addi	r1,r1,16

	beqlr+	cr7

	rlwinm	r3,r3,8,0,31	/* swap bytes for odd destination */

	blr



/* These shouldn't go in the fixup section, since that would

   cause the ex_table addresses to get out of order. */



src_error_4:

	mfctr	r6		/* update # bytes remaining from ctr */

	rlwimi	r5,r6,4,0,27

	b	79f

src_error_1:

	li	r6,0

	subi	r5,r5,2

95:	sth	r6,4(r4)

	addi	r4,r4,2

79:	srwi.	r6,r5,2

	beq	3f

	mtctr	r6

src_error_2:

	li	r6,0

96:	stwu	r6,4(r4)

	bdnz	96b

3:	andi.	r5,r5,3

	beq	src_error

src_error_3:

	li	r6,0

	mtctr	r5

	addi	r4,r4,3

97:	stbu	r6,1(r4)

	bdnz	97b

/* read fault */

src_error:

	cmpwi	0,r7,0

	beq	1f

	li	r6,-EFAULT

	stw	r6,0(r7)

1:	addze	r3,r0

	lwz	r7,12(r1)

	addi	r1,r1,16

	cmpwi	cr0,r7,0

	beqlr

	li	r0,-EFAULT

	stw	r0,0(r7)

	blr



/* write fault */

dst_error:

	cmpwi	0,r8,0

	beq	1f

	li	r6,-EFAULT

	stw	r6,0(r8)

1:	addze	r3,r0

	lwz	r8,8(r1)

	addi	r1,r1,16

	cmpwi	cr0,r8,0

	beqlr

	li	r0,-EFAULT

	stw	r0,0(r8)

	blr



	.section __ex_table,"a"

	.long	81b,src_error_1

	.long	91b,dst_error

	.long	71b,src_error_4

	.long	72b,src_error_4

	.long	73b,src_error_4

	.long	74b,src_error_4

	.long	75b,dst_error

	.long	76b,dst_error

	.long	77b,dst_error

	.long	78b,dst_error

	.long	82b,src_error_2

	.long	92b,dst_error

	.long	83b,src_error_3

	.long	93b,dst_error

	.long	84b,src_error_3

	.long	94b,dst_error

	.long	95b,dst_error

	.long	96b,dst_error

	.long	97b,dst_error
 
	.align	2

	.long	70b,src_error

	.long	71b,dst_error

	.long	72b,src_error

	.long	73b,dst_error

	.long	54b,dst_error

	.text



/*

 * this stuff handles faults in the cacheline loop and branches to either

 * src_error (if in read part) or dst_error (if in write part)

 */

	CSUM_COPY_16_BYTES_EXCODE(0)

#if L1_CACHE_BYTES >= 32

	CSUM_COPY_16_BYTES_EXCODE(1)

#if L1_CACHE_BYTES >= 64

	CSUM_COPY_16_BYTES_EXCODE(2)

	CSUM_COPY_16_BYTES_EXCODE(3)

#if L1_CACHE_BYTES >= 128

	CSUM_COPY_16_BYTES_EXCODE(4)

	CSUM_COPY_16_BYTES_EXCODE(5)

	CSUM_COPY_16_BYTES_EXCODE(6)

	CSUM_COPY_16_BYTES_EXCODE(7)

#endif

#endif

#endif



	.section __ex_table,"a"

	.align	2

	.long	30b,src_error

	.long	31b,dst_error

	.long	40b,src_error

	.long	41b,dst_error

	.long	50b,src_error

	.long	51b,dst_error