cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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csum-partial_64.c (2966B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * arch/x86_64/lib/csum-partial.c
      4 *
      5 * This file contains network checksum routines that are better done
      6 * in an architecture-specific manner due to speed.
      7 */
      8 
      9#include <linux/compiler.h>
     10#include <linux/export.h>
     11#include <asm/checksum.h>
     12#include <asm/word-at-a-time.h>
     13
     14static inline unsigned short from32to16(unsigned a) 
     15{
     16	unsigned short b = a >> 16; 
     17	asm("addw %w2,%w0\n\t"
     18	    "adcw $0,%w0\n" 
     19	    : "=r" (b)
     20	    : "0" (b), "r" (a));
     21	return b;
     22}
     23
     24/*
     25 * Do a checksum on an arbitrary memory area.
     26 * Returns a 32bit checksum.
     27 *
     28 * This isn't as time critical as it used to be because many NICs
     29 * do hardware checksumming these days.
     30 *
     31 * Still, with CHECKSUM_COMPLETE this is called to compute
     32 * checksums on IPv6 headers (40 bytes) and other small parts.
     33 * it's best to have buff aligned on a 64-bit boundary
     34 */
     35__wsum csum_partial(const void *buff, int len, __wsum sum)
     36{
     37	u64 temp64 = (__force u64)sum;
     38	unsigned odd, result;
     39
     40	odd = 1 & (unsigned long) buff;
     41	if (unlikely(odd)) {
     42		if (unlikely(len == 0))
     43			return sum;
     44		temp64 = ror32((__force u32)sum, 8);
     45		temp64 += (*(unsigned char *)buff << 8);
     46		len--;
     47		buff++;
     48	}
     49
     50	while (unlikely(len >= 64)) {
     51		asm("addq 0*8(%[src]),%[res]\n\t"
     52		    "adcq 1*8(%[src]),%[res]\n\t"
     53		    "adcq 2*8(%[src]),%[res]\n\t"
     54		    "adcq 3*8(%[src]),%[res]\n\t"
     55		    "adcq 4*8(%[src]),%[res]\n\t"
     56		    "adcq 5*8(%[src]),%[res]\n\t"
     57		    "adcq 6*8(%[src]),%[res]\n\t"
     58		    "adcq 7*8(%[src]),%[res]\n\t"
     59		    "adcq $0,%[res]"
     60		    : [res] "+r" (temp64)
     61		    : [src] "r" (buff)
     62		    : "memory");
     63		buff += 64;
     64		len -= 64;
     65	}
     66
     67	if (len & 32) {
     68		asm("addq 0*8(%[src]),%[res]\n\t"
     69		    "adcq 1*8(%[src]),%[res]\n\t"
     70		    "adcq 2*8(%[src]),%[res]\n\t"
     71		    "adcq 3*8(%[src]),%[res]\n\t"
     72		    "adcq $0,%[res]"
     73			: [res] "+r" (temp64)
     74			: [src] "r" (buff)
     75			: "memory");
     76		buff += 32;
     77	}
     78	if (len & 16) {
     79		asm("addq 0*8(%[src]),%[res]\n\t"
     80		    "adcq 1*8(%[src]),%[res]\n\t"
     81		    "adcq $0,%[res]"
     82			: [res] "+r" (temp64)
     83			: [src] "r" (buff)
     84			: "memory");
     85		buff += 16;
     86	}
     87	if (len & 8) {
     88		asm("addq 0*8(%[src]),%[res]\n\t"
     89		    "adcq $0,%[res]"
     90			: [res] "+r" (temp64)
     91			: [src] "r" (buff)
     92			: "memory");
     93		buff += 8;
     94	}
     95	if (len & 7) {
     96		unsigned int shift = (8 - (len & 7)) * 8;
     97		unsigned long trail;
     98
     99		trail = (load_unaligned_zeropad(buff) << shift) >> shift;
    100
    101		asm("addq %[trail],%[res]\n\t"
    102		    "adcq $0,%[res]"
    103			: [res] "+r" (temp64)
    104			: [trail] "r" (trail));
    105	}
    106	result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
    107	if (unlikely(odd)) {
    108		result = from32to16(result);
    109		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
    110	}
    111	return (__force __wsum)result;
    112}
    113EXPORT_SYMBOL(csum_partial);
    114
    115/*
    116 * this routine is used for miscellaneous IP-like checksums, mainly
    117 * in icmp.c
    118 */
    119__sum16 ip_compute_csum(const void *buff, int len)
    120{
    121	return csum_fold(csum_partial(buff,len,0));
    122}
    123EXPORT_SYMBOL(ip_compute_csum);