checksum.h

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#ifndef _ASM_SCORE_CHECKSUM_H
#define _ASM_SCORE_CHECKSUM_H

#include <linux/in6.h>
#include <asm/uaccess.h>

/*
 * computes the checksum of a memory block at buff, length len,
 * and adds in "sum" (32-bit)
 *
 * returns a 32-bit number suitable for feeding into itself
 * or csum_tcpudp_magic
 *
 * this function must be called with even lengths, except
 * for the last fragment, which may be odd
 *
 * it's best to have buff aligned on a 32-bit boundary
 */
unsigned int csum_partial(const void *buff, int len, __wsum sum);
unsigned int csum_partial_copy_from_user(const char *src, char *dst, int len,
                    unsigned int sum, int *csum_err);
unsigned int csum_partial_copy(const char *src, char *dst,
                    int len, unsigned int sum);

/*
 * this is a new version of the above that records errors it finds in *errp,
 * but continues and zeros the rest of the buffer.
 */

/*
 * Copy and checksum to user
 */
#define HAVE_CSUM_COPY_USER
static inline
__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len,
            __wsum sum, int *err_ptr)
{
    sum = csum_partial(src, len, sum);
    if (copy_to_user(dst, src, len)) {
        *err_ptr = -EFAULT;
        return (__force __wsum) -1; /* invalid checksum */
    }
    return sum;
}


#define csum_partial_copy_nocheck csum_partial_copy
/*
 *  Fold a partial checksum without adding pseudo headers
 */

static inline __sum16 csum_fold(__wsum sum)
{
    /* the while loop is unnecessary really, it's always enough with two
       iterations */
    __asm__ __volatile__(
        ".set volatile\n\t"
        ".set\tr1\n\t"
        "slli\tr1,%0, 16\n\t"
        "add\t%0,%0, r1\n\t"
        "cmp.c\tr1, %0\n\t"
        "srli\t%0, %0, 16\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n\t"
        "1:ldi\tr30, 0xffff\n\t"
        "xor\t%0, %0, r30\n\t"
        "slli\t%0, %0, 16\n\t"
        "srli\t%0, %0, 16\n\t"
        ".set\tnor1\n\t"
        ".set optimize\n\t"
        : "=r" (sum)
        : "0" (sum));
    return sum;
}

/*
 *  This is a version of ip_compute_csum() optimized for IP headers,
 *  which always checksum on 4 octet boundaries.
 *
 *  By Jorge Cwik <[email protected]>, adapted for linux by
 *  Arnt Gulbrandsen.
 */
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
    unsigned int sum;
    unsigned long dummy;

    __asm__ __volatile__(
        ".set volatile\n\t"
        ".set\tnor1\n\t"
        "lw\t%0, [%1]\n\t"
        "subri\t%2, %2, 4\n\t"
        "slli\t%2, %2, 2\n\t"
        "lw\t%3, [%1, 4]\n\t"
        "add\t%2, %2, %1\n\t"
        "add\t%0, %0, %3\n\t"
        "cmp.c\t%3, %0\n\t"
        "lw\t%3, [%1, 8]\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n\t"
        "1:\n\t"
        "add\t%0, %0, %3\n\t"
        "cmp.c\t%3, %0\n\t"
        "lw\t%3, [%1, 12]\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n\t"
        "1:add\t%0, %0, %3\n\t"
        "cmp.c\t%3, %0\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n"

        "1:\tlw\t%3, [%1, 16]\n\t"
        "addi\t%1, 4\n\t"
        "add\t%0, %0, %3\n\t"
        "cmp.c\t%3, %0\n\t"
        "bleu\t2f\n\t"
        "addi\t%0, 0x1\n"
        "2:cmp.c\t%2, %1\n\t"
        "bne\t1b\n\t"

        ".set\tr1\n\t"
        ".set optimize\n\t"
        : "=&r" (sum), "=&r" (iph), "=&r" (ihl), "=&r" (dummy)
        : "1" (iph), "2" (ihl));

    return csum_fold(sum);
}

static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len,
        unsigned short proto, __wsum sum)
{
    unsigned long tmp = (ntohs(len) << 16) + proto * 256;
    __asm__ __volatile__(
        ".set volatile\n\t"
        "add\t%0, %0, %2\n\t"
        "cmp.c\t%2, %0\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n\t"
        "1:\n\t"
        "add\t%0, %0, %3\n\t"
        "cmp.c\t%3, %0\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n\t"
        "1:\n\t"
        "add\t%0, %0, %4\n\t"
        "cmp.c\t%4, %0\n\t"
        "bleu\t1f\n\t"
        "addi\t%0, 0x1\n\t"
        "1:\n\t"
        ".set optimize\n\t"
        : "=r" (sum)
        : "0" (daddr), "r"(saddr),
        "r" (tmp),
        "r" (sum));
    return sum;
}

/*
 * computes the checksum of the TCP/UDP pseudo-header
 * returns a 16-bit checksum, already complemented
 */
static inline __sum16
csum_tcpudp_magic(__be32 saddr, __be32 daddr, unsigned short len,
        unsigned short proto, __wsum sum)
{
    return csum_fold(csum_tcpudp_nofold(saddr, daddr, len, proto, sum));
}

/*
 * this routine is used for miscellaneous IP-like checksums, mainly
 * in icmp.c
 */

static inline unsigned short ip_compute_csum(const void *buff, int len)
{
    return csum_fold(csum_partial(buff, len, 0));
}

#define _HAVE_ARCH_IPV6_CSUM
static inline __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
                const struct in6_addr *daddr,
                __u32 len, unsigned short proto,
                __wsum sum)
{
    __asm__ __volatile__(
        ".set\tnoreorder\t\t\t# csum_ipv6_magic\n\t"
        ".set\tnoat\n\t"
        "addu\t%0, %5\t\t\t# proto (long in network byte order)\n\t"
        "sltu\t$1, %0, %5\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %6\t\t\t# csum\n\t"
        "sltu\t$1, %0, %6\n\t"
        "lw\t%1, 0(%2)\t\t\t# four words source address\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 4(%2)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 8(%2)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 12(%2)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 0(%3)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 4(%3)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 8(%3)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "lw\t%1, 12(%3)\n\t"
        "addu\t%0, $1\n\t"
        "addu\t%0, %1\n\t"
        "sltu\t$1, %0, %1\n\t"
        "addu\t%0, $1\t\t\t# Add final carry\n\t"
        ".set\tnoat\n\t"
        ".set\tnoreorder"
        : "=r" (sum), "=r" (proto)
        : "r" (saddr), "r" (daddr),
          "0" (htonl(len)), "1" (htonl(proto)), "r" (sum));

    return csum_fold(sum);
}
#endif /* _ASM_SCORE_CHECKSUM_H */