/* SPDX-License-Identifier: GPL-2.0 */
/*
 *  arch/arm/include/asm/checksum.h
 *
 * IP checksum routines
 *
 * Copyright (C) Original authors of ../asm-i386/checksum.h
 * Copyright (C) 1996-1999 Russell King
 */
#ifndef __ASM_ARM_CHECKSUM_H
#define __ASM_ARM_CHECKSUM_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
 */
__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
 */

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

__wsum
csum_partial_copy_from_user(const void __user *src, void *dst, int len);

#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
#define _HAVE_ARCH_CSUM_AND_COPY
static inline
__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
{
        if (!access_ok(src, len))
                return 0;

        return csum_partial_copy_from_user(src, dst, len);
}

/*
 *      Fold a partial checksum without adding pseudo headers
 */
static inline __sum16 csum_fold(__wsum sum)
{
        __asm__(
        "add    %0, %1, %1, ror #16     @ csum_fold"
        : "=r" (sum)
        : "r" (sum)
        : "cc");
        return (__force __sum16)(~(__force u32)sum >> 16);
}

/*
 *      This is a version of ip_compute_csum() optimized for IP headers,
 *      which always checksum on 4 octet boundaries.
 */
static inline __sum16
ip_fast_csum(const void *iph, unsigned int ihl)
{
        unsigned int tmp1;
        __wsum sum;

        __asm__ __volatile__(
        "ldr    %0, [%1], #4            @ ip_fast_csum          \n\
        ldr     %3, [%1], #4                                    \n\
        sub     %2, %2, #5                                      \n\
        adds    %0, %0, %3                                      \n\
        ldr     %3, [%1], #4                                    \n\
        adcs    %0, %0, %3                                      \n\
        ldr     %3, [%1], #4                                    \n\
1:      adcs    %0, %0, %3                                      \n\
        ldr     %3, [%1], #4                                    \n\
        tst     %2, #15                 @ do this carefully     \n\
        subne   %2, %2, #1              @ without destroying    \n\
        bne     1b                      @ the carry flag        \n\
        adcs    %0, %0, %3                                      \n\
        adc     %0, %0, #0"
        : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (tmp1)
        : "1" (iph), "2" (ihl)
        : "cc", "memory");
        return csum_fold(sum);
}

static inline __wsum
csum_tcpudp_nofold(__be32 saddr, __be32 daddr, __u32 len,
                   __u8 proto, __wsum sum)
{
        u32 lenprot = len + proto;
        if (__builtin_constant_p(sum) && sum == 0) {
                __asm__(
                "adds   %0, %1, %2      @ csum_tcpudp_nofold0   \n\t"
#ifdef __ARMEB__
                "adcs   %0, %0, %3                              \n\t"
#else
                "adcs   %0, %0, %3, ror #8                      \n\t"
#endif
                "adc    %0, %0, #0"
                : "=&r" (sum)
                : "r" (daddr), "r" (saddr), "r" (lenprot)
                : "cc");
        } else {
                __asm__(
                "adds   %0, %1, %2      @ csum_tcpudp_nofold    \n\t"
                "adcs   %0, %0, %3                              \n\t"
#ifdef __ARMEB__
                "adcs   %0, %0, %4                              \n\t"
#else
                "adcs   %0, %0, %4, ror #8                      \n\t"
#endif
                "adc    %0, %0, #0"
                : "=&r"(sum)
                : "r" (sum), "r" (daddr), "r" (saddr), "r" (lenprot)
                : "cc");
        }
        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
extern __wsum
__csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr, __be32 len,
                __be32 proto, __wsum sum);

static inline __sum16
csum_ipv6_magic(const struct in6_addr *saddr, const struct in6_addr *daddr,
                __u32 len, __u8 proto, __wsum sum)
{
        return csum_fold(__csum_ipv6_magic(saddr, daddr, htonl(len),
                                           htonl(proto), sum));
}
#endif