/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_CHECKSUM_32_H
#define _ASM_X86_CHECKSUM_32_H

#include <linux/in6.h>
#include <linux/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
 */
asmlinkage __wsum csum_partial(const void *buff, int len, __wsum sum);

/*
 * the same as csum_partial, but copies from src while it
 * checksums, and handles user-space pointer exceptions correctly, when needed.
 *
 * here even more important to align src and dst on a 32-bit (or even
 * better 64-bit) boundary
 */

asmlinkage __wsum csum_partial_copy_generic(const void *src, void *dst, int len);

/*
 *      Note: when you get a NULL pointer exception here this means someone
 *      passed in an incorrect kernel address to one of these functions.
 *
 *      If you use these functions directly please don't forget the
 *      access_ok().
 */
static inline __wsum csum_partial_copy_nocheck(const void *src, void *dst, int len)
{
        return csum_partial_copy_generic(src, dst, len);
}

static inline __wsum csum_and_copy_from_user(const void __user *src,
                                             void *dst, int len)
{
        __wsum ret;

        might_sleep();
        if (!user_access_begin(src, len))
                return 0;
        ret = csum_partial_copy_generic((__force void *)src, dst, len);
        user_access_end();

        return ret;
}

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

        asm volatile("movl (%1), %0     ;\n"
                     "subl $4, %2       ;\n"
                     "jbe 2f            ;\n"
                     "addl 4(%1), %0    ;\n"
                     "adcl 8(%1), %0    ;\n"
                     "adcl 12(%1), %0;\n"
                     "1:        adcl 16(%1), %0 ;\n"
                     "lea 4(%1), %1     ;\n"
                     "decl %2   ;\n"
                     "jne 1b            ;\n"
                     "adcl $0, %0       ;\n"
                     "movl %0, %2       ;\n"
                     "shrl $16, %0      ;\n"
                     "addw %w2, %w0     ;\n"
                     "adcl $0, %0       ;\n"
                     "notl %0   ;\n"
                     "2:                ;\n"
        /* Since the input registers which are loaded with iph and ihl
           are modified, we must also specify them as outputs, or gcc
           will assume they contain their original values. */
                     : "=r" (sum), "=r" (iph), "=r" (ihl)
                     : "1" (iph), "2" (ihl)
                     : "memory");
        return (__force __sum16)sum;
}

/*
 *      Fold a partial checksum
 */

static inline __sum16 csum_fold(__wsum sum)
{
        asm("addl %1, %0                ;\n"
            "adcl $0xffff, %0   ;\n"
            : "=r" (sum)
            : "r" ((__force u32)sum << 16),
              "0" ((__force u32)sum & 0xffff0000));
        return (__force __sum16)(~(__force u32)sum >> 16);
}

static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr,
                                        __u32 len, __u8 proto,
                                        __wsum sum)
{
        asm("addl %1, %0        ;\n"
            "adcl %2, %0        ;\n"
            "adcl %3, %0        ;\n"
            "adcl $0, %0        ;\n"
            : "=r" (sum)
            : "g" (daddr), "g"(saddr),
              "g" ((len + proto) << 8), "0" (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,
                                        __u32 len, __u8 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 __sum16 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, __u8 proto, __wsum sum)
{
        asm("addl 0(%1), %0     ;\n"
            "adcl 4(%1), %0     ;\n"
            "adcl 8(%1), %0     ;\n"
            "adcl 12(%1), %0    ;\n"
            "adcl 0(%2), %0     ;\n"
            "adcl 4(%2), %0     ;\n"
            "adcl 8(%2), %0     ;\n"
            "adcl 12(%2), %0    ;\n"
            "adcl %3, %0        ;\n"
            "adcl %4, %0        ;\n"
            "adcl $0, %0        ;\n"
            : "=&r" (sum)
            : "r" (saddr), "r" (daddr),
              "r" (htonl(len)), "r" (htonl(proto)), "0" (sum)
            : "memory");

        return csum_fold(sum);
}

/*
 *      Copy and checksum to user
 */
static inline __wsum csum_and_copy_to_user(const void *src,
                                           void __user *dst,
                                           int len)
{
        __wsum ret;

        might_sleep();
        if (!user_access_begin(dst, len))
                return 0;

        ret = csum_partial_copy_generic(src, (__force void *)dst, len);
        user_access_end();
        return ret;
}

#endif /* _ASM_X86_CHECKSUM_32_H */