// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
/*
 * Copyright (c) 2016 Mellanox Technologies Ltd. All rights reserved.
 * Copyright (c) 2015 System Fabric Works, Inc. All rights reserved.
 */

#include <linux/crc32.h>

#include "rxe.h"
#include "rxe_loc.h"

/**
 * rxe_crc32() - Compute cumulative crc32 for a contiguous segment
 * @rxe: rdma_rxe device object
 * @crc: starting crc32 value from previous segments
 * @next: starting address of current segment
 * @len: length of current segment
 *
 * Return: the cumulative crc32 checksum
 */
static __be32 rxe_crc32(struct rxe_dev *rxe, __be32 crc, void *next, size_t len)
{
        return (__force __be32)crc32_le((__force u32)crc, next, len);
}

/**
 * rxe_icrc_hdr() - Compute the partial ICRC for the network and transport
 *                headers of a packet.
 * @skb: packet buffer
 * @pkt: packet information
 *
 * Return: the partial ICRC
 */
static __be32 rxe_icrc_hdr(struct sk_buff *skb, struct rxe_pkt_info *pkt)
{
        unsigned int bth_offset = 0;
        struct iphdr *ip4h = NULL;
        struct ipv6hdr *ip6h = NULL;
        struct udphdr *udph;
        struct rxe_bth *bth;
        __be32 crc;
        int length;
        int hdr_size = sizeof(struct udphdr) +
                (skb->protocol == htons(ETH_P_IP) ?
                sizeof(struct iphdr) : sizeof(struct ipv6hdr));
        /* pseudo header buffer size is calculate using ipv6 header size since
         * it is bigger than ipv4
         */
        u8 pshdr[sizeof(struct udphdr) +
                sizeof(struct ipv6hdr) +
                RXE_BTH_BYTES];

        /* This seed is the result of computing a CRC with a seed of
         * 0xfffffff and 8 bytes of 0xff representing a masked LRH.
         */
        crc = (__force __be32)0xdebb20e3;

        if (skb->protocol == htons(ETH_P_IP)) { /* IPv4 */
                memcpy(pshdr, ip_hdr(skb), hdr_size);
                ip4h = (struct iphdr *)pshdr;
                udph = (struct udphdr *)(ip4h + 1);

                ip4h->ttl = 0xff;
                ip4h->check = CSUM_MANGLED_0;
                ip4h->tos = 0xff;
        } else {                                /* IPv6 */
                memcpy(pshdr, ipv6_hdr(skb), hdr_size);
                ip6h = (struct ipv6hdr *)pshdr;
                udph = (struct udphdr *)(ip6h + 1);

                memset(ip6h->flow_lbl, 0xff, sizeof(ip6h->flow_lbl));
                ip6h->priority = 0xf;
                ip6h->hop_limit = 0xff;
        }
        udph->check = CSUM_MANGLED_0;

        bth_offset += hdr_size;

        memcpy(&pshdr[bth_offset], pkt->hdr, RXE_BTH_BYTES);
        bth = (struct rxe_bth *)&pshdr[bth_offset];

        /* exclude bth.resv8a */
        bth->qpn |= cpu_to_be32(~BTH_QPN_MASK);

        length = hdr_size + RXE_BTH_BYTES;
        crc = rxe_crc32(pkt->rxe, crc, pshdr, length);

        /* And finish to compute the CRC on the remainder of the headers. */
        crc = rxe_crc32(pkt->rxe, crc, pkt->hdr + RXE_BTH_BYTES,
                        rxe_opcode[pkt->opcode].length - RXE_BTH_BYTES);
        return crc;
}

/**
 * rxe_icrc_check() - Compute ICRC for a packet and compare to the ICRC
 *                    delivered in the packet.
 * @skb: packet buffer
 * @pkt: packet information
 *
 * Return: 0 if the values match else an error
 */
int rxe_icrc_check(struct sk_buff *skb, struct rxe_pkt_info *pkt)
{
        __be32 *icrcp;
        __be32 pkt_icrc;
        __be32 icrc;

        icrcp = (__be32 *)(pkt->hdr + pkt->paylen - RXE_ICRC_SIZE);
        pkt_icrc = *icrcp;

        icrc = rxe_icrc_hdr(skb, pkt);
        icrc = rxe_crc32(pkt->rxe, icrc, (u8 *)payload_addr(pkt),
                                payload_size(pkt) + bth_pad(pkt));
        icrc = ~icrc;

        if (unlikely(icrc != pkt_icrc))
                return -EINVAL;

        return 0;
}

/**
 * rxe_icrc_generate() - compute ICRC for a packet.
 * @skb: packet buffer
 * @pkt: packet information
 */
void rxe_icrc_generate(struct sk_buff *skb, struct rxe_pkt_info *pkt)
{
        __be32 *icrcp;
        __be32 icrc;

        icrcp = (__be32 *)(pkt->hdr + pkt->paylen - RXE_ICRC_SIZE);
        icrc = rxe_icrc_hdr(skb, pkt);
        icrc = rxe_crc32(pkt->rxe, icrc, (u8 *)payload_addr(pkt),
                                payload_size(pkt) + bth_pad(pkt));
        *icrcp = ~icrc;
}