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- /* SPDX-License-Identifier: GPL-2.0 */
- #ifndef __UM_CHECKSUM_H
- #define __UM_CHECKSUM_H
- #include <linux/string.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
- */
- extern __wsum csum_partial(const void *buff, int len, __wsum sum);
- /**
- * csum_fold - Fold and invert a 32bit checksum.
- * sum: 32bit unfolded sum
- *
- * Fold a 32bit running checksum to 16bit and invert it. This is usually
- * the last step before putting a checksum into a packet.
- * Make sure not to mix with 64bit checksums.
- */
- static inline __sum16 csum_fold(__wsum sum)
- {
- __asm__(
- " addl %1,%0\n"
- " adcl $0xffff,%0"
- : "=r" (sum)
- : "r" ((__force u32)sum << 16),
- "0" ((__force u32)sum & 0xffff0000)
- );
- return (__force __sum16)(~(__force u32)sum >> 16);
- }
- /**
- * csum_tcpup_nofold - Compute an IPv4 pseudo header checksum.
- * @saddr: source address
- * @daddr: destination address
- * @len: length of packet
- * @proto: ip protocol of packet
- * @sum: initial sum to be added in (32bit unfolded)
- *
- * Returns the pseudo header checksum the input data. Result is
- * 32bit unfolded.
- */
- 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));
- }
- /**
- * ip_fast_csum - Compute the IPv4 header checksum efficiently.
- * iph: ipv4 header
- * ihl: length of header / 4
- */
- static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
- {
- unsigned int sum;
- asm( " 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:"
- /* Since the input registers which are loaded with iph and ipl
- 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;
- }
- #ifdef CONFIG_X86_32
- # include "checksum_32.h"
- #else
- # include "checksum_64.h"
- #endif
- #endif
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