diff options
| -rw-r--r-- | arch/x86/lib/csum-partial_64.c | 81 |
1 files changed, 37 insertions, 44 deletions
diff --git a/arch/x86/lib/csum-partial_64.c b/arch/x86/lib/csum-partial_64.c index 557e42ede68e..c9dae65ac01b 100644 --- a/arch/x86/lib/csum-partial_64.c +++ b/arch/x86/lib/csum-partial_64.c @@ -16,6 +16,20 @@ static inline __wsum csum_finalize_sum(u64 temp64) return (__force __wsum)((temp64 + ror64(temp64, 32)) >> 32); } +static inline unsigned long update_csum_40b(unsigned long sum, const unsigned long m[5]) +{ + asm("addq %1,%0\n\t" + "adcq %2,%0\n\t" + "adcq %3,%0\n\t" + "adcq %4,%0\n\t" + "adcq %5,%0\n\t" + "adcq $0,%0" + :"+r" (sum) + :"m" (m[0]), "m" (m[1]), "m" (m[2]), + "m" (m[3]), "m" (m[4])); + return sum; +} + /* * Do a checksum on an arbitrary memory area. * Returns a 32bit checksum. @@ -31,52 +45,31 @@ __wsum csum_partial(const void *buff, int len, __wsum sum) { u64 temp64 = (__force u64)sum; - /* - * 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 $0,%[res]" - : [res] "+r"(temp64) - : [src] "r"(buff), "m"(*(const char(*)[40])buff)); - return csum_finalize_sum(temp64); + /* Do two 40-byte chunks in parallel to get better ILP */ + if (likely(len >= 80)) { + u64 temp64_2 = 0; + do { + temp64 = update_csum_40b(temp64, buff); + temp64_2 = update_csum_40b(temp64_2, buff + 40); + buff += 80; + len -= 80; + } while (len >= 80); + + asm("addq %1,%0\n\t" + "adcq $0,%0" + :"+r" (temp64): "r" (temp64_2)); } - 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)); + /* + * len == 40 is the hot case due to IPv6 headers, so return + * early for that exact case without checking the tail bytes. + */ + if (len >= 40) { + temp64 = update_csum_40b(temp64, buff); + len -= 40; + if (!len) + return csum_finalize_sum(temp64); + buff += 40; } if (len & 32) { |