diff options
Diffstat (limited to 'arch/x86/lib/csum-partial_64.c')
| -rw-r--r-- | arch/x86/lib/csum-partial_64.c | 101 |
1 files changed, 68 insertions, 33 deletions
diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c index 50734a23034c..cea25ca8b8cf 100644 --- a/arch/x86/lib/csum-partial_64.c +++ b/arch/x86/lib/csum-partial_64.c @@ -5,22 +5,34 @@ * 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> #include <asm/word-at-a-time.h> -static inline unsigned short from32to16(unsigned a) +static inline unsigned short from32to16(unsigned a) { - unsigned short b = a >> 16; + unsigned short b = a >> 16; asm("addw %w2,%w0\n\t" - "adcw $0,%w0\n" + "adcw $0,%w0\n" : "=r" (b) : "0" (b), "r" (a)); return b; } +static inline __wsum csum_tail(u64 temp64, int odd) +{ + unsigned int result; + + result = add32_with_carry(temp64 >> 32, temp64 & 0xffffffff); + if (unlikely(odd)) { + result = from32to16(result); + result = ((result >> 8) & 0xff) | ((result & 0xff) << 8); + } + return (__force __wsum)result; +} + /* * Do a checksum on an arbitrary memory area. * Returns a 32bit checksum. @@ -35,7 +47,7 @@ static inline unsigned short from32to16(unsigned a) __wsum csum_partial(const void *buff, int len, __wsum sum) { u64 temp64 = (__force u64)sum; - unsigned odd, result; + unsigned odd; odd = 1 & (unsigned long) buff; if (unlikely(odd)) { @@ -47,21 +59,52 @@ __wsum csum_partial(const void *buff, int len, __wsum sum) buff++; } - while (unlikely(len >= 64)) { + /* + * len == 40 is the hot case due to IPv6 headers, but annotating it likely() + * has noticeable negative affect on codegen for all other cases with + * minimal performance benefit here. + */ + if (len == 40) { 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; + : [res] "+r"(temp64) + : [src] "r"(buff), "m"(*(const char(*)[40])buff)); + return csum_tail(temp64, odd); + } + if (unlikely(len >= 64)) { + /* + * Extra accumulators for better ILP in the loop. + */ + u64 tmp_accum, tmp_carries; + + asm("xorl %k[tmp_accum],%k[tmp_accum]\n\t" + "xorl %k[tmp_carries],%k[tmp_carries]\n\t" + "subl $64, %[len]\n\t" + "1:\n\t" + "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" + "adcl $0,%k[tmp_carries]\n\t" + "addq 4*8(%[src]),%[tmp_accum]\n\t" + "adcq 5*8(%[src]),%[tmp_accum]\n\t" + "adcq 6*8(%[src]),%[tmp_accum]\n\t" + "adcq 7*8(%[src]),%[tmp_accum]\n\t" + "adcl $0,%k[tmp_carries]\n\t" + "addq $64, %[src]\n\t" + "subl $64, %[len]\n\t" + "jge 1b\n\t" + "addq %[tmp_accum],%[res]\n\t" + "adcq %[tmp_carries],%[res]\n\t" + "adcq $0,%[res]" + : [tmp_accum] "=&r"(tmp_accum), + [tmp_carries] "=&r"(tmp_carries), [res] "+r"(temp64), + [len] "+r"(len), [src] "+r"(buff) + : "m"(*(const char *)buff)); } if (len & 32) { @@ -70,45 +113,37 @@ __wsum csum_partial(const void *buff, int len, __wsum sum) "adcq 2*8(%[src]),%[res]\n\t" "adcq 3*8(%[src]),%[res]\n\t" "adcq $0,%[res]" - : [res] "+r" (temp64) - : [src] "r" (buff) - : "memory"); + : [res] "+r"(temp64) + : [src] "r"(buff), "m"(*(const char(*)[32])buff)); 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"); + : [res] "+r"(temp64) + : [src] "r"(buff), "m"(*(const char(*)[16])buff)); buff += 16; } if (len & 8) { asm("addq 0*8(%[src]),%[res]\n\t" "adcq $0,%[res]" - : [res] "+r" (temp64) - : [src] "r" (buff) - : "memory"); + : [res] "+r"(temp64) + : [src] "r"(buff), "m"(*(const char(*)[8])buff)); buff += 8; } if (len & 7) { - unsigned int shift = (8 - (len & 7)) * 8; + unsigned int shift = (-len << 3) & 63; 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)); + : [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 (__force __wsum)result; + return csum_tail(temp64, odd); } EXPORT_SYMBOL(csum_partial); @@ -118,6 +153,6 @@ EXPORT_SYMBOL(csum_partial); */ __sum16 ip_compute_csum(const void *buff, int len) { - return csum_fold(csum_partial(buff,len,0)); + return csum_fold(csum_partial(buff, len, 0)); } EXPORT_SYMBOL(ip_compute_csum); |