linux/arch/x86/include/asm/checksum_32.h
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   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_X86_CHECKSUM_32_H
   3#define _ASM_X86_CHECKSUM_32_H
   4
   5#include <linux/in6.h>
   6#include <linux/uaccess.h>
   7
   8/*
   9 * computes the checksum of a memory block at buff, length len,
  10 * and adds in "sum" (32-bit)
  11 *
  12 * returns a 32-bit number suitable for feeding into itself
  13 * or csum_tcpudp_magic
  14 *
  15 * this function must be called with even lengths, except
  16 * for the last fragment, which may be odd
  17 *
  18 * it's best to have buff aligned on a 32-bit boundary
  19 */
  20asmlinkage __wsum csum_partial(const void *buff, int len, __wsum sum);
  21
  22/*
  23 * the same as csum_partial, but copies from src while it
  24 * checksums, and handles user-space pointer exceptions correctly, when needed.
  25 *
  26 * here even more important to align src and dst on a 32-bit (or even
  27 * better 64-bit) boundary
  28 */
  29
  30asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst, int len);
  31
  32/*
  33 *      Note: when you get a NULL pointer exception here this means someone
  34 *      passed in an incorrect kernel address to one of these functions.
  35 *
  36 *      If you use these functions directly please don't forget the
  37 *      access_ok().
  38 */
  39static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len)
  40{
  41        return csum_partial_copy_generic(src, dst, len);
  42}
  43
  44static inline __wsum csum_and_copy_from_user(const void __user *src,
  45                                             void *dst, int len)
  46{
  47        __wsum ret;
  48
  49        might_sleep();
  50        if (!user_access_begin(src, len))
  51                return 0;
  52        ret = csum_partial_copy_generic((__force void *)src, dst, len);
  53        user_access_end();
  54
  55        return ret;
  56}
  57
  58/*
  59 *      This is a version of ip_compute_csum() optimized for IP headers,
  60 *      which always checksum on 4 octet boundaries.
  61 *
  62 *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  63 *      Arnt Gulbrandsen.
  64 */
  65static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  66{
  67        unsigned int sum;
  68
  69        asm volatile("movl (%1), %0     ;\n"
  70                     "subl $4, %2       ;\n"
  71                     "jbe 2f            ;\n"
  72                     "addl 4(%1), %0    ;\n"
  73                     "adcl 8(%1), %0    ;\n"
  74                     "adcl 12(%1), %0;\n"
  75                     "1:        adcl 16(%1), %0 ;\n"
  76                     "lea 4(%1), %1     ;\n"
  77                     "decl %2   ;\n"
  78                     "jne 1b            ;\n"
  79                     "adcl $0, %0       ;\n"
  80                     "movl %0, %2       ;\n"
  81                     "shrl $16, %0      ;\n"
  82                     "addw %w2, %w0     ;\n"
  83                     "adcl $0, %0       ;\n"
  84                     "notl %0   ;\n"
  85                     "2:                ;\n"
  86        /* Since the input registers which are loaded with iph and ihl
  87           are modified, we must also specify them as outputs, or gcc
  88           will assume they contain their original values. */
  89                     : "=r" (sum), "=r" (iph), "=r" (ihl)
  90                     : "1" (iph), "2" (ihl)
  91                     : "memory");
  92        return (__force __sum16)sum;
  93}
  94
  95/*
  96 *      Fold a partial checksum
  97 */
  98
  99static inline __sum16 csum_fold(__wsum sum)
 100{
 101        asm("addl %1, %0                ;\n"
 102            "adcl $0xffff, %0   ;\n"
 103            : "=r" (sum)
 104            : "r" ((__force u32)sum << 16),
 105              "0" ((__force u32)sum & 0xffff0000));
 106        return (__force __sum16)(~(__force u32)sum >> 16);
 107}
 108
 109static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 110                                        __u32 len, __u8 proto,
 111                                        __wsum sum)
 112{
 113        asm("addl %1, %0        ;\n"
 114            "adcl %2, %0        ;\n"
 115            "adcl %3, %0        ;\n"
 116            "adcl $0, %0        ;\n"
 117            : "=r" (sum)
 118            : "g" (daddr), "g"(saddr),
 119              "g" ((len + proto) << 8), "0" (sum));
 120        return sum;
 121}
 122
 123/*
 124 * computes the checksum of the TCP/UDP pseudo-header
 125 * returns a 16-bit checksum, already complemented
 126 */
 127static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 128                                        __u32 len, __u8 proto,
 129                                        __wsum sum)
 130{
 131        return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 132}
 133
 134/*
 135 * this routine is used for miscellaneous IP-like checksums, mainly
 136 * in icmp.c
 137 */
 138
 139static inline __sum16 ip_compute_csum(const void *buff, int len)
 140{
 141    return csum_fold(csum_partial(buff, len, 0));
 142}
 143
 144#define _HAVE_ARCH_IPV6_CSUM
 145static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 146                                      const struct in6_addr *daddr,
 147                                      __u32 len, __u8 proto, __wsum sum)
 148{
 149        asm("addl 0(%1), %0     ;\n"
 150            "adcl 4(%1), %0     ;\n"
 151            "adcl 8(%1), %0     ;\n"
 152            "adcl 12(%1), %0    ;\n"
 153            "adcl 0(%2), %0     ;\n"
 154            "adcl 4(%2), %0     ;\n"
 155            "adcl 8(%2), %0     ;\n"
 156            "adcl 12(%2), %0    ;\n"
 157            "adcl %3, %0        ;\n"
 158            "adcl %4, %0        ;\n"
 159            "adcl $0, %0        ;\n"
 160            : "=&r" (sum)
 161            : "r" (saddr), "r" (daddr),
 162              "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
 163            : "memory");
 164
 165        return csum_fold(sum);
 166}
 167
 168/*
 169 *      Copy and checksum to user
 170 */
 171static inline __wsum csum_and_copy_to_user(const void *src,
 172                                           void __user *dst,
 173                                           int len)
 174{
 175        __wsum ret;
 176
 177        might_sleep();
 178        if (!user_access_begin(dst, len))
 179                return 0;
 180
 181        ret = csum_partial_copy_generic(src, (__force void *)dst, len);
 182        user_access_end();
 183        return ret;
 184}
 185
 186#endif /* _ASM_X86_CHECKSUM_32_H */
 187
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