1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2002, 2003 Andi Kleen, SuSE Labs.
4 *
5 * Wrappers of assembly checksum functions for x86-64.
6 */
7#include <asm/checksum.h>
8#include <linux/export.h>
9#include <linux/uaccess.h>
10#include <asm/smap.h>
11
12/**
13 * csum_and_copy_from_user - Copy and checksum from user space.
14 * @src: source address (user space)
15 * @dst: destination address
16 * @len: number of bytes to be copied.
17 *
18 * Returns an 32bit unfolded checksum of the buffer.
19 * src and dst are best aligned to 64bits.
20 */
21__wsum
22csum_and_copy_from_user(const void __user *src, void *dst, int len)
23{
24 __wsum sum;
25
26 might_sleep();
27 if (!user_access_begin(src, len))
28 return 0;
29 sum = csum_partial_copy_generic((__force const void *)src, dst, len);
30 user_access_end();
31 return sum;
32}
33
34/**
35 * csum_and_copy_to_user - Copy and checksum to user space.
36 * @src: source address
37 * @dst: destination address (user space)
38 * @len: number of bytes to be copied.
39 *
40 * Returns an 32bit unfolded checksum of the buffer.
41 * src and dst are best aligned to 64bits.
42 */
43__wsum
44csum_and_copy_to_user(const void *src, void __user *dst, int len)
45{
46 __wsum sum;
47
48 might_sleep();
49 if (!user_access_begin(dst, len))
50 return 0;
51 sum = csum_partial_copy_generic(src, (void __force *)dst, len);
52 user_access_end();
53 return sum;
54}
55
56/**
57 * csum_partial_copy_nocheck - Copy and checksum.
58 * @src: source address
59 * @dst: destination address
60 * @len: number of bytes to be copied.
61 *
62 * Returns an 32bit unfolded checksum of the buffer.
63 */
64__wsum
65csum_partial_copy_nocheck(const void *src, void *dst, int len)
66{
67 return csum_partial_copy_generic(src, dst, len);
68}
69EXPORT_SYMBOL(csum_partial_copy_nocheck);
70
71__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
72 const struct in6_addr *daddr,
73 __u32 len, __u8 proto, __wsum sum)
74{
75 __u64 rest, sum64;
76
77 rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
78 (__force __u64)sum;
79
80 asm(" addq (%[saddr]),%[sum]\n"
81 " adcq 8(%[saddr]),%[sum]\n"
82 " adcq (%[daddr]),%[sum]\n"
83 " adcq 8(%[daddr]),%[sum]\n"
84 " adcq $0,%[sum]\n"
85
86 : [sum] "=r" (sum64)
87 : "[sum]" (rest), [saddr] "r" (saddr), [daddr] "r" (daddr));
88
89 return csum_fold(
90 csum: (__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
91}
92EXPORT_SYMBOL(csum_ipv6_magic);
93

source code of linux/arch/x86/lib/csum-wrappers_64.c