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csum_partial.c
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csum_partial.c
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// 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 <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <time.h>
typedef uint32_t __wsum;
typedef uint64_t u64;
typedef uint32_t u32;
# define unlikely(x) __builtin_expect(!!(x), 0)
#define LOOPCOUNT 102400
#define PACKETSIZE 40
static inline unsigned long load_unaligned_zeropad(const void *addr)
{
unsigned long ret, dummy;
asm(
"1:\tmov %2,%0\n"
"2:\n"
".section .fixup,\"ax\"\n"
"3:\t"
"lea %2,%1\n\t"
"and %3,%1\n\t"
"mov (%1),%0\n\t"
"leal %2,%%ecx\n\t"
"andl %4,%%ecx\n\t"
"shll $3,%%ecx\n\t"
"shr %%cl,%0\n\t"
"jmp 2b\n"
".previous\n"
:"=&r" (ret),"=&c" (dummy)
:"m" (*(unsigned long *)addr),
"i" (-sizeof(unsigned long)),
"i" (sizeof(unsigned long)-1));
return ret;
}
static inline unsigned add32_with_carry(unsigned a, unsigned b)
{
asm("addl %2,%0\n\t"
"adcl $0,%0"
: "=r" (a)
: "0" (a), "rm" (b));
return a;
}
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 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.
*
* Still, with CHECKSUM_COMPLETE this is called to compute
* checksums on IPv6 headers (40 bytes) and other small parts.
* it's best to have buff aligned on a 64-bit boundary
*/
__wsum csum_partial(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned odd, result;
odd = 1 & (unsigned long) buff;
if (unlikely(odd)) {
if (unlikely(len == 0))
return sum;
temp64 += (*(unsigned char *)buff << 8);
len--;
buff++;
}
while (unlikely(len >= 64)) {
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 64;
len -= 64;
}
if (len & 32) {
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 32;
}
if (len & 16) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq 1*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 16;
}
if (len & 8) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 8;
}
if (len & 7) {
unsigned int shift = (8 - (len & 7)) * 8;
unsigned long trail;
trail = (load_unaligned_zeropad(buff) << shift) >> shift;
asm("addq %[trail],%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [trail] "r" (trail));
}
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
if (unlikely(odd)) {
result = from32to16(result);
result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
}
return (__wsum)result;
}
__wsum __csum_partial(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned odd, result;
odd = 1 & (unsigned long) buff;
if (unlikely(odd)) {
if (unlikely(len == 0))
return sum;
temp64 += (*(unsigned char *)buff << 8);
len--;
buff++;
}
while (unlikely(len >= 64)) {
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 64;
len -= 64;
}
if (len & 32) {
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 32;
}
if (len & 16) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq 1*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 16;
}
if (len & 8) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 8;
}
if (len & 7) {
unsigned int shift = (8 - (len & 7)) * 8;
unsigned long trail;
trail = (load_unaligned_zeropad(buff) << shift) >> shift;
asm("addq %[trail],%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [trail] "r" (trail));
}
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
if (unlikely(odd)) {
result = from32to16(result);
result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
}
return (__wsum)result;
}
__wsum csum_partial40_no_odd(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned result;
while (unlikely(len >= 64)) {
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 64;
len -= 64;
}
if (len & 32) {
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 32;
}
if (len & 16) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq 1*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 16;
}
if (len & 8) {
asm("addq 0*8(%[src]),%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
buff += 8;
}
if (len & 7) {
unsigned int shift = (8 - (len & 7)) * 8;
unsigned long trail;
trail = (load_unaligned_zeropad(buff) << shift) >> shift;
asm("addq %[trail],%[res]\n\t"
"adcq $0,%[res]"
: [res] "+r" (temp64)
: [trail] "r" (trail));
}
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
return (__wsum)result;
}
__wsum csum_partial40_dead_code(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned result;
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 $0,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory");
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
return (__wsum)result;
}
__wsum csum_partial40_ACX(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned result;
/*
* the xorq not only zeroes r9, it also clears CF and OF so that
* the first adcx/adox work as expected getting no input carry
* while setting the output carry in the correct flags
*/
asm("xorq %%r9, %%r9 \n\t"
"movq 0*8(%[src]), %%rcx \n\t"
"adcx 1*8(%[src]), %%rcx \n\t"
"adcx 2*8(%[src]), %%rcx \n\t"
"adcx 3*8(%[src]), %%rcx \n\t"
"adcx %%r9, %%rcx \n\t"
"adox 4*8(%[src]), %[res]\n\t"
"adox %%rcx, %[res]\n\t"
"adox %%r9, %[res]"
: [res] "+d" (temp64)
: [src] "r" (buff)
: "memory", "rcx", "r9");
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
return (__wsum)result;
}
__wsum csum_partial40_2_streams(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned result;
asm("xorq %%r9, %%r9\n\t"
"movq 0*8(%[src]),%%rcx\n\t"
"addq 1*8(%[src]),%%rcx\n\t"
"adcq 2*8(%[src]),%%rcx\n\t"
"adcq 3*8(%[src]),%%rcx\n\t"
"adcq %%r9, %%rcx\n\t"
"addq 4*8(%[src]),%[res]\n\t"
"adcq %%rcx,%[res]\n\t"
"adcq %%r9,%[res]"
: [res] "+r" (temp64)
: [src] "r" (buff)
: "memory", "rcx", "r9");
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
return (__wsum)result;
}
__wsum csum_partial40_zero_sum(const void *buff, int len, __wsum sum)
{
u64 temp64 = (u64)sum;
unsigned result;
asm("movq 0*8(%[src]),%%rcx\n\t"
"addq 1*8(%[src]),%%rcx\n\t"
"adcq 2*8(%[src]),%%rcx\n\t"
"adcq $0, %%rcx\n\t"
"movq 3*8(%[src]),%[res]\n\t"
"addq 4*8(%[src]),%[res]\n\t"
"adcq %%rcx,%[res]\n\t"
"adcq $0,%[res]"
: [res] "=&r" (temp64)
: [src] "r" (buff)
: "memory", "rcx");
result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff);
return (__wsum)result;
}
__wsum csum_partial40_32bit(const void *buff, int len, __wsum sum)
{
__wsum temp32 = sum;
asm("movl 0*4(%[src]), %%r9d \n\t"
"movl 1*4(%[src]), %%r11d \n\t"
"movl 2*4(%[src]), %%ecx \n\t"
"addl 3*4(%[src]), %%r9d \n\t"
"adcl 4*4(%[src]), %%r9d \n\t"
"adcl $0, %%r9d \n\t"
"addl 5*4(%[src]), %%r11d \n\t"
"adcl 6*4(%[src]), %%r11d \n\t"
"adcl $0, %%r11d \n\t"
"addl 7*4(%[src]), %%ecx \n\t"
"adcl 8*4(%[src]), %%ecx \n\t"
"adcl $0, %%ecx \n\t"
"addl 9*4(%[src]), %%edx \n\t"
"adcl %%r9d, %%edx \n\t"
"adcl %%r11d, %%edx \n\t"
"adcl %%ecx, %%edx \n\t"
"adcl $0, %%edx \n\t"
: [res] "+d" (temp32)
: [src] "r" (buff)
: "memory", "rcx", "r9", "r11");
return temp32;
}
static inline __wsum csum_partial_no_odd(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return csum_partial40_no_odd(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum csum_specialized(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return __csum_partial(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum csum_partial_dead_code(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return csum_partial40_dead_code(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum csum_partial_ACX(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return csum_partial40_ACX(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum csum_partial_2_streams(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return csum_partial40_2_streams(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum csum_partial_32bit(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return csum_partial40_32bit(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum csum_partial_zero_sum(const void *buff, int len, __wsum sum)
{
if (__builtin_constant_p(len) && len == 40) {
return csum_partial40_zero_sum(buff, len, sum);
} else {
return __csum_partial(buff, len, sum);
}
}
static inline __wsum nulltest(const void *buff, int len, __wsum sum)
{
return 2;
}
double cycles[64];
int cyclecount[64];
double cycles2[64];
int cyclecount2[64];
__wsum sum[64];
char *names[64];
void reset_data(void)
{
memset(cycles, 0, sizeof(cycles));
memset(cyclecount, 0, sizeof(cyclecount));
memset(names, 0, sizeof(names));
}
void decay_data(void)
{
int i;
for (i = 0; i < 64; i++) {
if (cyclecount[i] > 1024) {
cyclecount[i] /= 2;
cycles[i] /= 2.0;
}
}
for (i = 0; i < 64; i++) {
if (cyclecount2[i] > 1024) {
cyclecount2[i] /= 2;
cycles2[i] /= 2.0;
}
}
}
#define MEASURE(index, func, name) \
sum[index] = 0; \
start = __builtin_ia32_rdtscp(&A); \
for (i = 0; i < LOOPCOUNT; i++) \
sum[index] = func(buffer + 2 * i, PACKETSIZE, sum[index]); \
end = __builtin_ia32_rdtscp(&A); \
cycles[index] += 1.0 * (end - start)/LOOPCOUNT; \
cyclecount[index]++; \
names[index] = name; \
sum[index+1] = 0; \
start = __builtin_ia32_rdtscp(&A); \
for (i = 0; i < LOOPCOUNT; i++) \
sum[index+1] = func(buffer+1 + 2 * i, PACKETSIZE, sum[index+1]);\
end = __builtin_ia32_rdtscp(&A); \
cycles[index+1] += 1.0 * (end - start)/LOOPCOUNT; \
cyclecount[index+1]++; \
names[index+1] = name; \
\
sum[index] = 0; \
start = __builtin_ia32_rdtscp(&A); \
for (i = 0; i < LOOPCOUNT; i++) { \
asm volatile ("lfence\n\t.align 64\n\t" : : : "memory", "rcx"); \
sum[index] = func(buffer + 2 * i, PACKETSIZE, sum[index]); \
asm volatile (".align 64\n\tlfence\n\t" : : : "memory", "rcx"); \
} \
end = __builtin_ia32_rdtscp(&A); \
cycles2[index] += 1.0 * (end - start)/LOOPCOUNT; \
cyclecount2[index]++; \
names[index] = name; \
sum[index+1] = 0; \
start = __builtin_ia32_rdtscp(&A); \
for (i = 0; i < LOOPCOUNT; i++) { \
asm volatile ("lfence\n\t.align 64\n\t" : : : "memory", "rcx"); \
sum[index+1] = func(buffer+1 + 2 * i, PACKETSIZE, sum[index+1]);\
asm volatile (".align 64\n\tlfence\n\t" : : : "memory", "rcx"); \
} \
end = __builtin_ia32_rdtscp(&A); \
cycles2[index+1] += 1.0 * (end - start)/LOOPCOUNT; \
cyclecount2[index+1]++; \
names[index+1] = name; \
static void report(void)
{
static time_t prevtime;
int i;
if (time(NULL) - prevtime >= 1) {
printf("\033[H");
for (i = 2; i < 64; i+=2) {
if (names[i]) {
printf("%02i:\t%5.1f / %5.1f cycles\t(%08x)\t%s \n", i, cycles[i]/cyclecount[i], cycles2[i]/cyclecount2[i] - cycles2[0]/cyclecount2[0], sum[i], names[i]);
}
}
printf("------- odd alignment ----- \n");
for (i = 3; i < 64; i+=2) {
if (names[i]) {
printf("%02i:\t%5.1f / %5.1f cycles\t(%08x)\t%s \n", i, cycles[i]/cyclecount[i], cycles2[i]/cyclecount2[i] - cycles2[0]/cyclecount2[0], sum[i], names[i]);
}
}
prevtime = time(NULL);
}
decay_data();
}
int main(int argc, char **argv)
{
char buffer[LOOPCOUNT * 4];
int i;
unsigned int A;
uint32_t start, end;
printf("\033[H\033[J");
for (i = 0; i < LOOPCOUNT * 4; i++)
buffer[i] = rand() & 255;
/* power management warmup */
for (i = 0; i < 5000; i++) {
MEASURE(0, csum_partial, "Upcoming linux kernel version");
}
reset_data();
while (1) {
MEASURE(0, nulltest, "NULL test");
MEASURE(2, csum_partial, "Upcoming linux kernel version");
MEASURE(4, csum_specialized, "Specialized to size 40");
MEASURE(22, csum_partial_no_odd, "Odd-alignment handling removed");
MEASURE(24, csum_partial_dead_code, "Dead code elimination ");
MEASURE(28, csum_partial_ACX, "ADX interleaved ");
MEASURE(32, csum_partial_2_streams, "Work in progress non-ADX interleave ");
MEASURE(34, csum_partial_32bit, "32 bit train ");
MEASURE(36, csum_partial_zero_sum, "Assume zero input sum");
report();
}
}