checksum.h

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 *  arch/arm/include/asm/checksum.h
  4 *
  5 * IP checksum routines
  6 *
  7 * Copyright (C) Original authors of ../asm-i386/checksum.h
  8 * Copyright (C) 1996-1999 Russell King
  9 */
 10#ifndef __ASM_ARM_CHECKSUM_H
 11#define __ASM_ARM_CHECKSUM_H
 12
 13#include <linux/in6.h>
 14#include <linux/uaccess.h>
 15
 16/*
 17 * computes the checksum of a memory block at buff, length len,
 18 * and adds in "sum" (32-bit)
 19 *
 20 * returns a 32-bit number suitable for feeding into itself
 21 * or csum_tcpudp_magic
 22 *
 23 * this function must be called with even lengths, except
 24 * for the last fragment, which may be odd
 25 *
 26 * it's best to have buff aligned on a 32-bit boundary
 27 */
 28__wsum csum_partial(const void *buff, int len, __wsum sum);
 29
 30/*
 31 * the same as csum_partial, but copies from src while it
 32 * checksums, and handles user-space pointer exceptions correctly, when needed.
 33 *
 34 * here even more important to align src and dst on a 32-bit (or even
 35 * better 64-bit) boundary
 36 */
 37
 38__wsum
 39csum_partial_copy_nocheck(const void *src, void *dst, int len);
 40
 41__wsum
 42csum_partial_copy_from_user(const void __user *src, void *dst, int len);
 43
 44#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
 45#define _HAVE_ARCH_CSUM_AND_COPY
 46static inline
 47__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
 48{
 49	if (!access_ok(src, len))
 50		return 0;
 51
 52	return csum_partial_copy_from_user(src, dst, len);
 53}
 54
 55/*
 56 * 	Fold a partial checksum without adding pseudo headers
 57 */
 58static inline __sum16 csum_fold(__wsum sum)
 59{
 60	__asm__(
 61	"add	%0, %1, %1, ror #16	@ csum_fold"
 62	: "=r" (sum)
 63	: "r" (sum)
 64	: "cc");
 65	return (__force __sum16)(~(__force u32)sum >> 16);
 66}
 67
 68/*
 69 *	This is a version of ip_compute_csum() optimized for IP headers,
 70 *	which always checksum on 4 octet boundaries.
 71 */
 72static inline __sum16
 73ip_fast_csum(const void *iph, unsigned int ihl)
 74{
 75	unsigned int tmp1;
 76	__wsum sum;
 77
 78	__asm__ __volatile__(
 79	"ldr	%0, [%1], #4		@ ip_fast_csum		\n\
 80	ldr	%3, [%1], #4					\n\
 81	sub	%2, %2, #5					\n\
 82	adds	%0, %0, %3					\n\
 83	ldr	%3, [%1], #4					\n\
 84	adcs	%0, %0, %3					\n\
 85	ldr	%3, [%1], #4					\n\
 861:	adcs	%0, %0, %3					\n\
 87	ldr	%3, [%1], #4					\n\
 88	tst	%2, #15			@ do this carefully	\n\
 89	subne	%2, %2, #1		@ without destroying	\n\
 90	bne	1b			@ the carry flag	\n\
 91	adcs	%0, %0, %3					\n\
 92	adc	%0, %0, #0"
 93	: "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
 94	: "1" (iph), "2" (ihl)
 95	: "cc", "memory");
 96	return csum_fold(sum);
 97}
 98
 99static inline __wsum
100csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
101		   __u8 proto, __wsum sum)
102{
103	u32 lenprot = len + proto;
104	if (__builtin_constant_p(sum) && sum == 0) {
105		__asm__(
106		"adds	%0, %1, %2	@ csum_tcpudp_nofold0	\n\t"
107#ifdef __ARMEB__
108		"adcs	%0, %0, %3				\n\t"
109#else
110		"adcs	%0, %0, %3, ror #8			\n\t"
111#endif
112		"adc	%0, %0, #0"
113		: "=&r" (sum)
114		: "r" (daddr), "r" (saddr), "r" (lenprot)
115		: "cc");
116	} else {
117		__asm__(
118		"adds	%0, %1, %2	@ csum_tcpudp_nofold	\n\t"
119		"adcs	%0, %0, %3				\n\t"
120#ifdef __ARMEB__
121		"adcs	%0, %0, %4				\n\t"
122#else
123		"adcs	%0, %0, %4, ror #8			\n\t"
124#endif
125		"adc	%0, %0, #0"
126		: "=&r"(sum)
127		: "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot)
128		: "cc");
129	}
130	return sum;
131}	
132/*
133 * computes the checksum of the TCP/UDP pseudo-header
134 * returns a 16-bit checksum, already complemented
135 */
136static inline __sum16
137csum_tcpudp_magic(__be32 saddr, __be32 daddr, __u32 len,
138		  __u8 proto, __wsum sum)
139{
140	return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
141}
142
143
144/*
145 * this routine is used for miscellaneous IP-like checksums, mainly
146 * in icmp.c
147 */
148static inline __sum16
149ip_compute_csum(const void *buff, int len)
150{
151	return csum_fold(csum_partial(buff, len, 0));
152}
153
154#define _HAVE_ARCH_IPV6_CSUM
155extern __wsum
156__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
157		__be32 proto, __wsum sum);
158
159static inline __sum16
160csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
161		__u32 len, __u8 proto, __wsum sum)
162{
163	return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
164					   htonl(proto), sum));
165}
166#endif