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authorIvan Kokshaysky <ink@jurassic.park.msu.ru>2007-06-23 17:16:35 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-06-24 08:59:11 -0700
commit58ed2f9c75b719da4f494f24ed2d56d45f5b4959 (patch)
tree6ecb60cf2d7b18da36fd29f2a6bd03d15a8cfefb /arch/alpha/lib/ev6-csum_ipv6_magic.S
parent653d4876b730fedca8473481863cf700245e3582 (diff)
alpha: fix alignment problem in csum_ipv6_magic()
Hopefully this fixes http://bugzilla.kernel.org/show_bug.cgi?id=8635 The struct in6_addr passed to csum_ipv6_magic() is 4 byte aligned, so we can't use the regular 64-bit loads. Since the cost of handling of 4 byte and 1 byte aligned 64-bit data is roughly the same, this code can cope with any src/dst [mis]alignment. Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Richard Henderson <rth@twiddle.net> Cc: Dustin Marquess <jailbird@alcatraz.fdf.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/alpha/lib/ev6-csum_ipv6_magic.S')
-rw-r--r--arch/alpha/lib/ev6-csum_ipv6_magic.S42
1 files changed, 33 insertions, 9 deletions
diff --git a/arch/alpha/lib/ev6-csum_ipv6_magic.S b/arch/alpha/lib/ev6-csum_ipv6_magic.S
index de1948a69118..fc0bc399f872 100644
--- a/arch/alpha/lib/ev6-csum_ipv6_magic.S
+++ b/arch/alpha/lib/ev6-csum_ipv6_magic.S
@@ -46,6 +46,10 @@
* add the 3 low ushorts together, generating a uint
* a final add of the 2 lower ushorts
* truncating the result.
+ *
+ * Misalignment handling added by Ivan Kokshaysky <ink@jurassic.park.msu.ru>
+ * The cost is 16 instructions (~8 cycles), including two extra loads which
+ * may cause additional delay in rare cases (load-load replay traps).
*/
.globl csum_ipv6_magic
@@ -55,25 +59,45 @@
csum_ipv6_magic:
.prologue 0
- ldq $0,0($16) # L : Latency: 3
+ ldq_u $0,0($16) # L : Latency: 3
inslh $18,7,$4 # U : 0000000000AABBCC
- ldq $1,8($16) # L : Latency: 3
+ ldq_u $1,8($16) # L : Latency: 3
sll $19,8,$7 # U : U L U L : 0x00000000 00aabb00
+ and $16,7,$6 # E : src misalignment
+ ldq_u $5,15($16) # L : Latency: 3
zapnot $20,15,$20 # U : zero extend incoming csum
- ldq $2,0($17) # L : Latency: 3
- sll $19,24,$19 # U : U L L U : 0x000000aa bb000000
+ ldq_u $2,0($17) # L : U L U L : Latency: 3
+
+ extql $0,$6,$0 # U :
+ extqh $1,$6,$22 # U :
+ ldq_u $3,8($17) # L : Latency: 3
+ sll $19,24,$19 # U : U U L U : 0x000000aa bb000000
+
+ cmoveq $6,$31,$22 # E : src aligned?
+ ldq_u $23,15($17) # L : Latency: 3
inswl $18,3,$18 # U : 000000CCDD000000
+ addl $19,$7,$19 # E : U L U L : <sign bits>bbaabb00
- ldq $3,8($17) # L : Latency: 3
- bis $18,$4,$18 # E : 000000CCDDAABBCC
- addl $19,$7,$19 # E : <sign bits>bbaabb00
- nop # E : U L U L
+ or $0,$22,$0 # E : 1st src word complete
+ extql $1,$6,$1 # U :
+ or $18,$4,$18 # E : 000000CCDDAABBCC
+ extqh $5,$6,$5 # U : L U L U
+ and $17,7,$6 # E : dst misalignment
+ extql $2,$6,$2 # U :
+ or $1,$5,$1 # E : 2nd src word complete
+ extqh $3,$6,$22 # U : L U L U :
+
+ cmoveq $6,$31,$22 # E : dst aligned?
+ extql $3,$6,$3 # U :
addq $20,$0,$20 # E : begin summing the words
+ extqh $23,$6,$23 # U : L U L U :
+
srl $18,16,$4 # U : 0000000000CCDDAA
+ or $2,$22,$2 # E : 1st dst word complete
zap $19,0x3,$19 # U : <sign bits>bbaa0000
- nop # E : L U U L
+ or $3,$23,$3 # E : U L U L : 2nd dst word complete
cmpult $20,$0,$0 # E :
addq $20,$1,$20 # E :