root/arch/x86/include/asm/checksum_32.h

INCLUDED FROM

DEFINITIONS

1. csum_partial_copy_nocheck
2. csum_partial_copy_from_user
3. ip_fast_csum
4. csum_fold
5. csum_tcpudp_nofold
6. csum_tcpudp_magic
7. ip_compute_csum
8. csum_ipv6_magic
9. csum_and_copy_to_user

   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  */
  20 asmlinkage __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 
  30 asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst,
  31                                             int len, __wsum sum,
  32                                             int *src_err_ptr, int *dst_err_ptr);
  33 
  34 /*
  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.
  37  *
  38  *      If you use these functions directly please don't forget the
  39  *      access_ok().
  40  */
  41 static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst,
  42                                                int len, __wsum sum)
  43 {
  44         return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
  45 }
  46 
  47 static inline __wsum csum_partial_copy_from_user(const void __user *src,
  48                                                  void *dst,
  49                                                  int len, __wsum sum,
  50                                                  int *err_ptr)
  51 {
  52         __wsum ret;
  53 
  54         might_sleep();
  55         stac();
  56         ret = csum_partial_copy_generic((__force void *)src, dst,
  57                                         len, sum, err_ptr, NULL);
  58         clac();
  59 
  60         return ret;
  61 }
  62 
  63 /*
  64  *      This is a version of ip_compute_csum() optimized for IP headers,
  65  *      which always checksum on 4 octet boundaries.
  66  *
  67  *      By Jorge Cwik <jorge@laser.satlink.net>, adapted for linux by
  68  *      Arnt Gulbrandsen.
  69  */
  70 static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
  71 {
  72         unsigned int sum;
  73 
  74         asm volatile("movl (%1), %0     ;\n"
  75                      "subl $4, %2       ;\n"
  76                      "jbe 2f            ;\n"
  77                      "addl 4(%1), %0    ;\n"
  78                      "adcl 8(%1), %0    ;\n"
  79                      "adcl 12(%1), %0;\n"
  80                      "1:        adcl 16(%1), %0 ;\n"
  81                      "lea 4(%1), %1     ;\n"
  82                      "decl %2   ;\n"
  83                      "jne 1b            ;\n"
  84                      "adcl $0, %0       ;\n"
  85                      "movl %0, %2       ;\n"
  86                      "shrl $16, %0      ;\n"
  87                      "addw %w2, %w0     ;\n"
  88                      "adcl $0, %0       ;\n"
  89                      "notl %0   ;\n"
  90                      "2:                ;\n"
  91         /* Since the input registers which are loaded with iph and ihl
  92            are modified, we must also specify them as outputs, or gcc
  93            will assume they contain their original values. */
  94                      : "=r" (sum), "=r" (iph), "=r" (ihl)
  95                      : "1" (iph), "2" (ihl)
  96                      : "memory");
  97         return (__force __sum16)sum;
  98 }
  99 
 100 /*
 101  *      Fold a partial checksum
 102  */
 103 
 104 static inline __sum16 csum_fold(__wsum sum)
 105 {
 106         asm("addl %1, %0                ;\n"
 107             "adcl $0xffff, %0   ;\n"
 108             : "=r" (sum)
 109             : "r" ((__force u32)sum << 16),
 110               "0" ((__force u32)sum & 0xffff0000));
 111         return (__force __sum16)(~(__force u32)sum >> 16);
 112 }
 113 
 114 static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
 115                                         __u32 len, __u8 proto,
 116                                         __wsum sum)
 117 {
 118         asm("addl %1, %0        ;\n"
 119             "adcl %2, %0        ;\n"
 120             "adcl %3, %0        ;\n"
 121             "adcl $0, %0        ;\n"
 122             : "=r" (sum)
 123             : "g" (daddr), "g"(saddr),
 124               "g" ((len + proto) << 8), "0" (sum));
 125         return sum;
 126 }
 127 
 128 /*
 129  * computes the checksum of the TCP/UDP pseudo-header
 130  * returns a 16-bit checksum, already complemented
 131  */
 132 static inline __sum16 csum_tcpudp_magic(__be32 saddr, __be32 daddr,
 133                                         __u32 len, __u8 proto,
 134                                         __wsum sum)
 135 {
 136         return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
 137 }
 138 
 139 /*
 140  * this routine is used for miscellaneous IP-like checksums, mainly
 141  * in icmp.c
 142  */
 143 
 144 static inline __sum16 ip_compute_csum(const void *buff, int len)
 145 {
 146     return csum_fold(csum_partial(buff, len, 0));
 147 }
 148 
 149 #define _HAVE_ARCH_IPV6_CSUM
 150 static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
 151                                       const struct in6_addr *daddr,
 152                                       __u32 len, __u8 proto, __wsum sum)
 153 {
 154         asm("addl 0(%1), %0     ;\n"
 155             "adcl 4(%1), %0     ;\n"
 156             "adcl 8(%1), %0     ;\n"
 157             "adcl 12(%1), %0    ;\n"
 158             "adcl 0(%2), %0     ;\n"
 159             "adcl 4(%2), %0     ;\n"
 160             "adcl 8(%2), %0     ;\n"
 161             "adcl 12(%2), %0    ;\n"
 162             "adcl %3, %0        ;\n"
 163             "adcl %4, %0        ;\n"
 164             "adcl $0, %0        ;\n"
 165             : "=&r" (sum)
 166             : "r" (saddr), "r" (daddr),
 167               "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
 168             : "memory");
 169 
 170         return csum_fold(sum);
 171 }
 172 
 173 /*
 174  *      Copy and checksum to user
 175  */
 176 #define HAVE_CSUM_COPY_USER
 177 static inline __wsum csum_and_copy_to_user(const void *src,
 178                                            void __user *dst,
 179                                            int len, __wsum sum,
 180                                            int *err_ptr)
 181 {
 182         __wsum ret;
 183 
 184         might_sleep();
 185         if (access_ok(dst, len)) {
 186                 stac();
 187                 ret = csum_partial_copy_generic(src, (__force void *)dst,
 188                                                 len, sum, NULL, err_ptr);
 189                 clac();
 190                 return ret;
 191         }
 192 
 193         if (len)
 194                 *err_ptr = -EFAULT;
 195 
 196         return (__force __wsum)-1; /* invalid checksum */
 197 }
 198 
 199 #endif /* _ASM_X86_CHECKSUM_32_H */