124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* arch/x86_64/lib/csum-partial.c
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*
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* This file contains network checksum routines that are better done
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* in an architecture-specific manner due to speed.
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*/
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#include <linux/compiler.h>
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#include <linux/export.h>
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#include <asm/checksum.h>
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#include <asm/word-at-a-time.h>
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static inline unsigned short from32to16(unsigned a)
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{
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unsigned short b = a >> 16;
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asm("addw %w2,%w0\n\t"
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"adcw $0,%w0\n"
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: "=r" (b)
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: "0" (b), "r" (a));
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return b;
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}
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/*
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* Do a checksum on an arbitrary memory area.
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* Returns a 32bit checksum.
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*
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* This isn't as time critical as it used to be because many NICs
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* do hardware checksumming these days.
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*
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* Still, with CHECKSUM_COMPLETE this is called to compute
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* checksums on IPv6 headers (40 bytes) and other small parts.
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* it's best to have buff aligned on a 64-bit boundary
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*/
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__wsum csum_partial(const void *buff, int len, __wsum sum)
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{
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u64 temp64 = (__force u64)sum;
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unsigned odd, result;
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odd = 1 & (unsigned long) buff;
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if (unlikely(odd)) {
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if (unlikely(len == 0))
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return sum;
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temp64 = ror32((__force u32)sum, 8);
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temp64 += (*(unsigned char *)buff << 8);
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len--;
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buff++;
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}
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while (unlikely(len >= 64)) {
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asm("addq 0*8(%[src]),%[res]\n\t"
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"adcq 1*8(%[src]),%[res]\n\t"
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"adcq 2*8(%[src]),%[res]\n\t"
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"adcq 3*8(%[src]),%[res]\n\t"
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"adcq 4*8(%[src]),%[res]\n\t"
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"adcq 5*8(%[src]),%[res]\n\t"
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"adcq 6*8(%[src]),%[res]\n\t"
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"adcq 7*8(%[src]),%[res]\n\t"
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"adcq $0,%[res]"
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: [res] "+r" (temp64)
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: [src] "r" (buff)
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: "memory");
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buff += 64;
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len -= 64;
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}
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if (len & 32) {
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asm("addq 0*8(%[src]),%[res]\n\t"
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"adcq 1*8(%[src]),%[res]\n\t"
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"adcq 2*8(%[src]),%[res]\n\t"
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"adcq 3*8(%[src]),%[res]\n\t"
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"adcq $0,%[res]"
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: [res] "+r" (temp64)
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: [src] "r" (buff)
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: "memory");
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buff += 32;
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}
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if (len & 16) {
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asm("addq 0*8(%[src]),%[res]\n\t"
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"adcq 1*8(%[src]),%[res]\n\t"
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"adcq $0,%[res]"
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: [res] "+r" (temp64)
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: [src] "r" (buff)
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: "memory");
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buff += 16;
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}
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if (len & 8) {
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asm("addq 0*8(%[src]),%[res]\n\t"
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"adcq $0,%[res]"
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: [res] "+r" (temp64)
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: [src] "r" (buff)
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: "memory");
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buff += 8;
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}
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if (len & 7) {
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unsigned int shift = (8 - (len & 7)) * 8;
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unsigned long trail;
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trail = (load_unaligned_zeropad(buff) << shift) >> shift;
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asm("addq %[trail],%[res]\n\t"
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"adcq $0,%[res]"
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: [res] "+r" (temp64)
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: [trail] "r" (trail));
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}
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result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
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if (unlikely(odd)) {
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result = from32to16(result);
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result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
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}
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return (__force __wsum)result;
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}
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EXPORT_SYMBOL(csum_partial);
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/*
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* this routine is used for miscellaneous IP-like checksums, mainly
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* in icmp.c
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*/
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__sum16 ip_compute_csum(const void *buff, int len)
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{
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return csum_fold(csum_partial(buff,len,0));
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}
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EXPORT_SYMBOL(ip_compute_csum);
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