text: // 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 "rxe.h"
  #include "rxe_loc.h"
  
  /* Compute a partial ICRC for all the IB transport headers. */
  u32 rxe_icrc_hdr(struct rxe_pkt_info *pkt, struct sk_buff *skb)
  {
  	unsigned int bth_offset = 0;
  	struct iphdr *ip4h = NULL;
  	struct ipv6hdr *ip6h = NULL;
  	struct udphdr *udph;
  	struct rxe_bth *bth;
  	int 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 = 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;
  }
  