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-rw-r--r--arch/powerpc/lib/checksum_64.S193
1 files changed, 153 insertions, 40 deletions
diff --git a/arch/powerpc/lib/checksum_64.S b/arch/powerpc/lib/checksum_64.S
index ef96c6c..404d5a6 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,