root/arch/x86/lib/csum-wrappers_64.c

DEFINITIONS

1. csum_partial_copy_from_user
2. csum_partial_copy_to_user
3. csum_partial_copy_nocheck
4. csum_ipv6_magic

/*
 * 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>

/**
 * csum_partial_copy_from_user - Copy and checksum from user space.
 * @src: source address (user space)
 * @dst: destination address
 * @len: number of bytes to be copied.
 * @isum: initial sum that is added into the result (32bit unfolded)
 * @errp: set to -EFAULT for an bad source address.
 *
 * Returns an 32bit unfolded checksum of the buffer.
 * src and dst are best aligned to 64bits.
 */
__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);

/**
 * csum_partial_copy_to_user - Copy and checksum to user space.
 * @src: source address
 * @dst: destination address (user space)
 * @len: number of bytes to be copied.
 * @isum: initial sum that is added into the result (32bit unfolded)
 * @errp: set to -EFAULT for an bad destination address.
 *
 * Returns an 32bit unfolded checksum of the buffer.
 * src and dst are best aligned to 64bits.
 */
__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);

/**
 * csum_partial_copy_nocheck - Copy and checksum.
 * @src: source address
 * @dst: destination address
 * @len: number of bytes to be copied.
 * @isum: initial sum that is added into the result (32bit unfolded)
 *
 * Returns an 32bit unfolded checksum of the buffer.
 */
__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);