diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/lib/checksum_64.S | 193 |
1 files changed, 153 insertions, 40 deletions
diff --git a/arch/powerpc/lib/checksum_64.S b/arch/powerpc/lib/checksum_64.S index ef96c6c58ef..404d5a6e338 100644 --- a/arch/powerpc/lib/checksum_64.S +++ b/arch/powerpc/lib/checksum_64.S @@ -65,55 +65,168 @@ _GLOBAL(csum_tcpudp_magic) srwi r3,r3,16 blr +#define STACKFRAMESIZE 256 +#define STK_REG(i) (112 + ((i)-14)*8) + /* * Computes the checksum of a memory block at buff, length len, * and adds in "sum" (32-bit). * - * This code assumes at least halfword alignment, though the length - * can be any number of bytes. The sum is accumulated in r5. - * * csum_partial(r3=buff, r4=len, r5=sum) */ _GLOBAL(csum_partial) - subi r3,r3,8 /* we'll offset by 8 for the loads */ - srdi. r6,r4,3 /* divide by 8 for doubleword count */ - addic r5,r5,0 /* clear carry */ - beq 3f /* if we're doing < 8 bytes */ - andi. r0,r3,2 /* aligned on a word boundary already? */ - beq+ 1f - lhz r6,8(r3) /* do 2 bytes to get aligned */ - addi r3,r3,2 - subi r4,r4,2 - addc r5,r5,r6 - srdi. r6,r4,3 /* recompute number of doublewords */ - beq 3f /* any left? */ -1: mtctr r6 -2: ldu r6,8(r3) /* main sum loop */ - adde r5,r5,r6 - bdnz 2b - andi. r4,r4,7 /* compute bytes left to sum after doublewords */ -3: cmpwi 0,r4,4 /* is at least a full word left? */ - blt 4f - lwz r6,8(r3) /* sum this word */ + addic r0,r5,0 /* clear carry */ + + srdi. r6,r4,3 /* less than 8 bytes? */ + beq .Lcsum_tail_word + + /* + * If only halfword aligned, align to a double word. Since odd + * aligned addresses should be rare and they would require more + * work to calculate the correct checksum, we ignore that case + * and take the potential slowdown of unaligned loads. + */ + rldicl. r6,r3,64-1,64-2 /* r6 = (r3 & 0x3) >> 1 */ + beq .Lcsum_aligned + + li r7,4 + sub r6,r7,r6 + mtctr r6 + +1: + lhz r6,0(r3) /* align to doubleword */ + subi r4,r4,2 + addi r3,r3,2 + adde r0,r0,r6 + bdnz 1b + +.Lcsum_aligned: + /* + * We unroll the loop such that each iteration is 64 bytes with an + * entry and exit limb of 64 bytes, meaning a minimum size of + * 128 bytes. + */ + srdi. r6,r4,7 + beq .Lcsum_tail_doublewords /* len < 128 */ + + srdi r6,r4,6 + subi r6,r6,1 + mtctr r6 + + stdu r1,-STACKFRAMESIZE(r1) + std r14,STK_REG(r14)(r1) + std r15,STK_REG(r15)(r1) + std r16,STK_REG(r16)(r1) + + ld r6,0(r3) + ld r9,8(r3) + + ld r10,16(r3) + ld r11,24(r3) + + /* + * On POWER6 and POWER7 back to back addes take 2 cycles because of + * the XER dependency. This means the fastest this loop can go is + * 16 cycles per iteration. The scheduling of the loop below has + * been shown to hit this on both POWER6 and POWER7. + */ + .align 5 +2: + adde r0,r0,r6 + ld r12,32(r3) + ld r14,40(r3) + + adde r0,r0,r9 + ld r15,48(r3) + ld r16,56(r3) + addi r3,r3,64 + + adde r0,r0,r10 + + adde r0,r0,r11 + + adde r0,r0,r12 + + adde r0,r0,r14 + + adde r0,r0,r15 + ld r6,0(r3) + ld r9,8(r3) + + adde r0,r0,r16 + ld r10,16(r3) + ld r11,24(r3) + bdnz 2b + + + adde r0,r0,r6 + ld r12,32(r3) + ld r14,40(r3) + + adde r0,r0,r9 + ld r15,48(r3) + ld r16,56(r3) + addi r3,r3,64 + + adde r0,r0,r10 + adde r0,r0,r11 + adde r0,r0,r12 + adde r0,r0,r14 + adde r0,r0,r15 + adde r0,r0,r16 + + ld r14,STK_REG(r14)(r1) + ld r15,STK_REG(r15)(r1) + ld r16,STK_REG(r16)(r1) + addi r1,r1,STACKFRAMESIZE + + andi. r4,r4,63 + +.Lcsum_tail_doublewords: /* Up to 127 bytes to go */ + srdi. r6,r4,3 + beq .Lcsum_tail_word + + mtctr r6 +3: + ld r6,0(r3) + addi r3,r3,8 + adde r0,r0,r6 + bdnz 3b + + andi. r4,r4,7 + +.Lcsum_tail_word: /* Up to 7 bytes to go */ + srdi. r6,r4,2 + beq .Lcsum_tail_halfword + + lwz r6,0(r3) addi r3,r3,4 + adde r0,r0,r6 subi r4,r4,4 - adde r5,r5,r6 -4: cmpwi 0,r4,2 /* is at least a halfword left? */ - blt+ 5f - lhz r6,8(r3) /* sum this halfword */ - addi r3,r3,2 - subi r4,r4,2 - adde r5,r5,r6 -5: cmpwi 0,r4,1 /* is at least a byte left? */ - bne+ 6f - lbz r6,8(r3) /* sum this byte */ - slwi r6,r6,8 /* this byte is assumed to be the upper byte of a halfword */ - adde r5,r5,r6 -6: addze r5,r5 /* add in final carry */ - rldicl r4,r5,32,0 /* fold two 32-bit halves together */ - add r3,r4,r5 - srdi r3,r3,32 - blr + +.Lcsum_tail_halfword: /* Up to 3 bytes to go */ + srdi. r6,r4,1 + beq .Lcsum_tail_byte + + lhz r6,0(r3) + addi r3,r3,2 + adde r0,r0,r6 + subi r4,r4,2 + +.Lcsum_tail_byte: /* Up to 1 byte to go */ + andi. r6,r4,1 + beq .Lcsum_finish + + lbz r6,0(r3) + sldi r9,r6,8 /* Pad the byte out to 16 bits */ + adde r0,r0,r9 + +.Lcsum_finish: + addze r0,r0 /* add in final carry */ + rldicl r4,r0,32,0 /* fold two 32 bit halves together */ + add r3,r4,r0 + srdi r3,r3,32 + blr /* * Computes the checksum of a memory block at src, length len, |