xref: /openbmc/linux/arch/powerpc/lib/checksum_32.S (revision c900529f3d9161bfde5cca0754f83b4d3c3e0220)

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * This file contains assembly-language implementations
 * of IP-style 1's complement checksum routines.
 *
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 * Severely hacked about by Paul Mackerras (paulus@cs.anu.edu.au).
 */

#include <linux/export.h>
#include <linux/sys.h>
#include <asm/processor.h>
#include <asm/cache.h>
#include <asm/errno.h>
#include <asm/ppc_asm.h>

	.text

/*
 * computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * __csum_partial(buff, len, sum)
 */
_GLOBAL(__csum_partial)
	subi	r3,r3,4
	srawi.	r6,r4,2		/* Divide len by 4 and also clear carry */
	beq	3f		/* if we're doing < 4 bytes */
	andi.	r0,r3,2		/* Align buffer to longword boundary */
	beq+	1f
	lhz	r0,4(r3)	/* do 2 bytes to get aligned */
	subi	r4,r4,2
	addi	r3,r3,2
	srwi.	r6,r4,2		/* # words to do */
	adde	r5,r5,r0
	beq	3f
1:	andi.	r6,r6,3		/* Prepare to handle words 4 by 4 */
	beq	21f
	mtctr	r6
2:	lwzu	r0,4(r3)
	adde	r5,r5,r0
	bdnz	2b
21:	srwi.	r6,r4,4		/* # blocks of 4 words to do */
	beq	3f
	lwz	r0,4(r3)
	mtctr	r6
	lwz	r6,8(r3)
	adde	r5,r5,r0
	lwz	r7,12(r3)
	adde	r5,r5,r6
	lwzu	r8,16(r3)
	adde	r5,r5,r7
	bdz	23f
22:	lwz	r0,4(r3)
	adde	r5,r5,r8
	lwz	r6,8(r3)
	adde	r5,r5,r0
	lwz	r7,12(r3)
	adde	r5,r5,r6
	lwzu	r8,16(r3)
	adde	r5,r5,r7
	bdnz	22b
23:	adde	r5,r5,r8
3:	andi.	r0,r4,2
	beq+	4f
	lhz	r0,4(r3)
	addi	r3,r3,2
	adde	r5,r5,r0
4:	andi.	r0,r4,1
	beq+	5f
	lbz	r0,4(r3)
	slwi	r0,r0,8		/* Upper byte of word */
	adde	r5,r5,r0
5:	addze	r3,r5		/* add in final carry */
	blr
EXPORT_SYMBOL(__csum_partial)

/*
 * Computes the checksum of a memory block at src, length len,
 * and adds in 0xffffffff, while copying the block to dst.
 * If an access exception occurs it returns zero.
 *
 * csum_partial_copy_generic(src, dst, len)
 */
#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)		\
	EX_TABLE(8 ## n ## 0b, fault);	\
	EX_TABLE(8 ## n ## 1b, fault);	\
	EX_TABLE(8 ## n ## 2b, fault);	\
	EX_TABLE(8 ## n ## 3b, fault);	\
	EX_TABLE(8 ## n ## 4b, fault);	\
	EX_TABLE(8 ## n ## 5b, fault);	\
	EX_TABLE(8 ## n ## 6b, fault);	\
	EX_TABLE(8 ## n ## 7b, fault);

	.text

CACHELINE_BYTES = L1_CACHE_BYTES
LG_CACHELINE_BYTES = L1_CACHE_SHIFT
CACHELINE_MASK = (L1_CACHE_BYTES-1)

_GLOBAL(csum_partial_copy_generic)
	li	r12,-1
	addic	r0,r0,0			/* clear carry */
	addi	r6,r4,-4
	neg	r0,r4
	addi	r4,r3,-4
	andi.	r0,r0,CACHELINE_MASK	/* # bytes to start of cache line */
	crset	4*cr7+eq
	beq	58f

	cmplw	0,r5,r0			/* is this more than total to do? */
	blt	63f			/* if not much to do */
	rlwinm	r7,r6,3,0x8
	rlwnm	r12,r12,r7,0,31	/* odd destination address: rotate one byte */
	cmplwi	cr7,r7,0	/* is destination address even ? */
	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
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
	beqlr+	cr7
	rlwinm	r3,r3,8,0,31	/* odd destination address: rotate one byte */
	blr

fault:
	li	r3,0
	blr

	EX_TABLE(70b, fault);
	EX_TABLE(71b, fault);
	EX_TABLE(72b, fault);
	EX_TABLE(73b, fault);
	EX_TABLE(54b, fault);

/*
 * this stuff handles faults in the cacheline loop and branches to either
 * fault (if in read part) or fault (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

	EX_TABLE(30b, fault);
	EX_TABLE(31b, fault);
	EX_TABLE(40b, fault);
	EX_TABLE(41b, fault);
	EX_TABLE(50b, fault);
	EX_TABLE(51b, fault);

EXPORT_SYMBOL(csum_partial_copy_generic)

/*
 * __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 *			   const struct in6_addr *daddr,
 *			   __u32 len, __u8 proto, __wsum sum)
 */

_GLOBAL(csum_ipv6_magic)
	lwz	r8, 0(r3)
	lwz	r9, 4(r3)
	addc	r0, r7, r8
	lwz	r10, 8(r3)
	adde	r0, r0, r9
	lwz	r11, 12(r3)
	adde	r0, r0, r10
	lwz	r8, 0(r4)
	adde	r0, r0, r11
	lwz	r9, 4(r4)
	adde	r0, r0, r8
	lwz	r10, 8(r4)
	adde	r0, r0, r9
	lwz	r11, 12(r4)
	adde	r0, r0, r10
	add	r5, r5, r6	/* assumption: len + proto doesn't carry */
	adde	r0, r0, r11
	adde	r0, r0, r5
	addze	r0, r0
	rotlwi	r3, r0, 16
	add	r3, r0, r3
	not	r3, r3
	rlwinm	r3, r3, 16, 16, 31
	blr
EXPORT_SYMBOL(csum_ipv6_magic)