1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_CHECKSUM_32_H
3 #define _ASM_X86_CHECKSUM_32_H
6 #include <linux/uaccess.h>
9 * computes the checksum of a memory block at buff, length len,
10 * and adds in "sum" (32-bit)
12 * returns a 32-bit number suitable for feeding into itself
13 * or csum_tcpudp_magic
15 * this function must be called with even lengths, except
16 * for the last fragment, which may be odd
18 * it's best to have buff aligned on a 32-bit boundary
20 asmlinkage __wsum csum_partial(const void *buff, int len, __wsum sum);
23 * the same as csum_partial, but copies from src while it
24 * checksums, and handles user-space pointer exceptions correctly, when needed.
26 * here even more important to align src and dst on a 32-bit (or even
27 * better 64-bit) boundary
30 asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst,
32 int *src_err_ptr, int *dst_err_ptr);
35 * Note: when you get a NULL pointer exception here this means someone
36 * passed in an incorrect kernel address to one of these functions.
38 * If you use these functions directly please don't forget the
41 static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst,
44 return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
47 static inline __wsum csum_and_copy_from_user(const void __user *src,
49 __wsum sum, int *err_ptr)
54 if (!user_access_begin(src, len)) {
59 ret = csum_partial_copy_generic((__force void *)src, dst,
60 len, sum, err_ptr, NULL);
67 * This is a version of ip_compute_csum() optimized for IP headers,
68 * which always checksum on 4 octet boundaries.
70 * By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
73 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
77 asm volatile("movl (%1), %0 ;\n"
83 "1: adcl 16(%1), %0 ;\n"
94 /* Since the input registers which are loaded with iph and ihl
95 are modified, we must also specify them as outputs, or gcc
96 will assume they contain their original values. */
97 : "=r" (sum), "=r" (iph), "=r" (ihl)
98 : "1" (iph), "2" (ihl)
100 return (__force __sum16)sum;
104 * Fold a partial checksum
107 static inline __sum16 csum_fold(__wsum sum)
109 asm("addl %1, %0 ;\n"
110 "adcl $0xffff, %0 ;\n"
112 : "r" ((__force u32)sum << 16),
113 "0" ((__force u32)sum & 0xffff0000));
114 return (__force __sum16)(~(__force u32)sum >> 16);
117 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
118 __u32 len, __u8 proto,
121 asm("addl %1, %0 ;\n"
126 : "g" (daddr), "g"(saddr),
127 "g" ((len + proto) << 8), "0" (sum));
132 * computes the checksum of the TCP/UDP pseudo-header
133 * returns a 16-bit checksum, already complemented
135 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
136 __u32 len, __u8 proto,
139 return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
143 * this routine is used for miscellaneous IP-like checksums, mainly
147 static inline __sum16 ip_compute_csum(const void *buff, int len)
149 return csum_fold(csum_partial(buff, len, 0));
152 #define _HAVE_ARCH_IPV6_CSUM
153 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
154 const struct in6_addr *daddr,
155 __u32 len, __u8 proto, __wsum sum)
157 asm("addl 0(%1), %0 ;\n"
160 "adcl 12(%1), %0 ;\n"
164 "adcl 12(%2), %0 ;\n"
169 : "r" (saddr), "r" (daddr),
170 "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
173 return csum_fold(sum);
177 * Copy and checksum to user
179 static inline __wsum csum_and_copy_to_user(const void *src,
187 if (user_access_begin(dst, len)) {
188 ret = csum_partial_copy_generic(src, (__force void *)dst,
189 len, sum, NULL, err_ptr);
197 return (__force __wsum)-1; /* invalid checksum */
200 #endif /* _ASM_X86_CHECKSUM_32_H */