csum-wrappers_64.c

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/*
 * Copyright 2002, 2003 Andi Kleen, SuSE Labs.
 * Subject to the GNU Public License v.2
 *
 * Wrappers of assembly checksum functions for x86-64.
 */
#include <asm/checksum.h>
#include <linux/module.h>

__wsum
csum_partial_copy_from_user(const void __user *src, void *dst,
                int len, __wsum isum, int *errp)
{
    might_sleep();
    *errp = 0;

    if (!likely(access_ok(VERIFY_READ, src, len)))
        goto out_err;

    /*
     * Why 6, not 7? To handle odd addresses aligned we
     * would need to do considerable complications to fix the
     * checksum which is defined as an 16bit accumulator. The
     * fix alignment code is primarily for performance
     * compatibility with 32bit and that will handle odd
     * addresses slowly too.
     */
    if (unlikely((unsigned long)src & 6)) {
        while (((unsigned long)src & 6) && len >= 2) {
            __u16 val16;

            *errp = __get_user(val16, (const __u16 __user *)src);
            if (*errp)
                return isum;

            *(__u16 *)dst = val16;
            isum = (__force __wsum)add32_with_carry(
                    (__force unsigned)isum, val16);
            src += 2;
            dst += 2;
            len -= 2;
        }
    }
    isum = csum_partial_copy_generic((__force const void *)src,
                dst, len, isum, errp, NULL);
    if (unlikely(*errp))
        goto out_err;

    return isum;

out_err:
    *errp = -EFAULT;
    memset(dst, 0, len);

    return isum;
}
EXPORT_SYMBOL(csum_partial_copy_from_user);

__wsum
csum_partial_copy_to_user(const void *src, void __user *dst,
              int len, __wsum isum, int *errp)
{
    might_sleep();

    if (unlikely(!access_ok(VERIFY_WRITE, dst, len))) {
        *errp = -EFAULT;
        return 0;
    }

    if (unlikely((unsigned long)dst & 6)) {
        while (((unsigned long)dst & 6) && len >= 2) {
            __u16 val16 = *(__u16 *)src;

            isum = (__force __wsum)add32_with_carry(
                    (__force unsigned)isum, val16);
            *errp = __put_user(val16, (__u16 __user *)dst);
            if (*errp)
                return isum;
            src += 2;
            dst += 2;
            len -= 2;
        }
    }

    *errp = 0;
    return csum_partial_copy_generic(src, (void __force *)dst,
                     len, isum, NULL, errp);
}
EXPORT_SYMBOL(csum_partial_copy_to_user);

__wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
{
    return csum_partial_copy_generic(src, dst, len, sum, NULL, NULL);
}
EXPORT_SYMBOL(csum_partial_copy_nocheck);

__sum16 csum_ipv6_magic(const struct in6_addr *saddr,
            const struct in6_addr *daddr,
            __u32 len, unsigned short proto, __wsum sum)
{
    __u64 rest, sum64;

    rest = (__force __u64)htonl(len) + (__force __u64)htons(proto) +
        (__force __u64)sum;

    asm("   addq (%[saddr]),%[sum]\n"
        "   adcq 8(%[saddr]),%[sum]\n"
        "   adcq (%[daddr]),%[sum]\n"
        "   adcq 8(%[daddr]),%[sum]\n"
        "   adcq $0,%[sum]\n"

        : [sum] "=r" (sum64)
        : "[sum]" (rest), [saddr] "r" (saddr), [daddr] "r" (daddr));

    return csum_fold(
           (__force __wsum)add32_with_carry(sum64 & 0xffffffff, sum64>>32));
}
EXPORT_SYMBOL(csum_ipv6_magic);