151 lines
3.5 KiB
C
151 lines
3.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* arch/x86_64/lib/csum-partial.c
|
|
*
|
|
* This file contains network checksum routines that are better done
|
|
* in an architecture-specific manner due to speed.
|
|
*/
|
|
|
|
#include <linux/compiler.h>
|
|
#include <linux/export.h>
|
|
#include <asm/checksum.h>
|
|
|
|
static inline unsigned short from32to16(unsigned a)
|
|
{
|
|
unsigned short b = a >> 16;
|
|
asm("addw %w2,%w0\n\t"
|
|
"adcw $0,%w0\n"
|
|
: "=r" (b)
|
|
: "0" (b), "r" (a));
|
|
return b;
|
|
}
|
|
|
|
/*
|
|
* Do a 64-bit checksum on an arbitrary memory area.
|
|
* Returns a 32bit checksum.
|
|
*
|
|
* This isn't as time critical as it used to be because many NICs
|
|
* do hardware checksumming these days.
|
|
*
|
|
* Things tried and found to not make it faster:
|
|
* Manual Prefetching
|
|
* Unrolling to an 128 bytes inner loop.
|
|
* Using interleaving with more registers to break the carry chains.
|
|
*/
|
|
static unsigned do_csum(const unsigned char *buff, unsigned len)
|
|
{
|
|
unsigned odd, count;
|
|
unsigned long result = 0;
|
|
|
|
if (unlikely(len == 0))
|
|
return result;
|
|
odd = 1 & (unsigned long) buff;
|
|
if (unlikely(odd)) {
|
|
result = *buff << 8;
|
|
len--;
|
|
buff++;
|
|
}
|
|
count = len >> 1; /* nr of 16-bit words.. */
|
|
if (count) {
|
|
if (2 & (unsigned long) buff) {
|
|
result += *(unsigned short *)buff;
|
|
count--;
|
|
len -= 2;
|
|
buff += 2;
|
|
}
|
|
count >>= 1; /* nr of 32-bit words.. */
|
|
if (count) {
|
|
unsigned long zero;
|
|
unsigned count64;
|
|
if (4 & (unsigned long) buff) {
|
|
result += *(unsigned int *) buff;
|
|
count--;
|
|
len -= 4;
|
|
buff += 4;
|
|
}
|
|
count >>= 1; /* nr of 64-bit words.. */
|
|
|
|
/* main loop using 64byte blocks */
|
|
zero = 0;
|
|
count64 = count >> 3;
|
|
while (count64) {
|
|
asm("addq 0*8(%[src]),%[res]\n\t"
|
|
"adcq 1*8(%[src]),%[res]\n\t"
|
|
"adcq 2*8(%[src]),%[res]\n\t"
|
|
"adcq 3*8(%[src]),%[res]\n\t"
|
|
"adcq 4*8(%[src]),%[res]\n\t"
|
|
"adcq 5*8(%[src]),%[res]\n\t"
|
|
"adcq 6*8(%[src]),%[res]\n\t"
|
|
"adcq 7*8(%[src]),%[res]\n\t"
|
|
"adcq %[zero],%[res]"
|
|
: [res] "=r" (result)
|
|
: [src] "r" (buff), [zero] "r" (zero),
|
|
"[res]" (result));
|
|
buff += 64;
|
|
count64--;
|
|
}
|
|
|
|
/* last up to 7 8byte blocks */
|
|
count %= 8;
|
|
while (count) {
|
|
asm("addq %1,%0\n\t"
|
|
"adcq %2,%0\n"
|
|
: "=r" (result)
|
|
: "m" (*(unsigned long *)buff),
|
|
"r" (zero), "0" (result));
|
|
--count;
|
|
buff += 8;
|
|
}
|
|
result = add32_with_carry(result>>32,
|
|
result&0xffffffff);
|
|
|
|
if (len & 4) {
|
|
result += *(unsigned int *) buff;
|
|
buff += 4;
|
|
}
|
|
}
|
|
if (len & 2) {
|
|
result += *(unsigned short *) buff;
|
|
buff += 2;
|
|
}
|
|
}
|
|
if (len & 1)
|
|
result += *buff;
|
|
result = add32_with_carry(result>>32, result & 0xffffffff);
|
|
if (unlikely(odd)) {
|
|
result = from32to16(result);
|
|
result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* 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 64-bit boundary
|
|
*/
|
|
__wsum csum_partial(const void *buff, int len, __wsum sum)
|
|
{
|
|
return (__force __wsum)add32_with_carry(do_csum(buff, len),
|
|
(__force u32)sum);
|
|
}
|
|
EXPORT_SYMBOL(csum_partial);
|
|
|
|
/*
|
|
* this routine is used for miscellaneous IP-like checksums, mainly
|
|
* in icmp.c
|
|
*/
|
|
__sum16 ip_compute_csum(const void *buff, int len)
|
|
{
|
|
return csum_fold(csum_partial(buff,len,0));
|
|
}
|
|
EXPORT_SYMBOL(ip_compute_csum);
|
|
|