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Message-ID: <20070617012020.A7626@jurassic.park.msu.ru> Date: Sun, 17 Jun 2007 01:20:20 +0400 From: Ivan Kokshaysky <ink@...assic.park.msu.ru> To: Andrew Morton <akpm@...ux-foundation.org>, Richard Henderson <rth@...ddle.net> Cc: linux-kernel@...r.kernel.org Subject: [patch] 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@...assic.park.msu.ru> Ivan. --- 2.6.22-rc4/arch/alpha/lib/ev6-csum_ipv6_magic.S Sun Feb 4 21:44:54 2007 +++ linux/arch/alpha/lib/ev6-csum_ipv6_magic.S Sun Jun 17 00:41:53 2007 @@ -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@...assic.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 - inswl $18,3,$18 # U : 000000CCDD000000 + 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 + or $18,$4,$18 # E : 000000CCDDAABBCC + extql $1,$6,$1 # U : U L L U : - ldq $3,8($17) # L : Latency: 3 - bis $18,$4,$18 # E : 000000CCDDAABBCC + or $0,$22,$0 # E : 1st src word complete + extqh $5,$6,$5 # U : addl $19,$7,$19 # E : <sign bits>bbaabb00 - nop # E : U L U L + and $17,7,$6 # E : L U L U : dst misalignment + inswl $18,3,$18 # U : 000000CCDD000000 + or $1,$5,$1 # E : 2nd src word complete + extql $2,$6,$2 # U : + extqh $3,$6,$22 # U : U L U 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 : --- 2.6.22-rc4/arch/alpha/lib/csum_ipv6_magic.S Sun Feb 4 21:44:54 2007 +++ linux/arch/alpha/lib/csum_ipv6_magic.S Sun Jun 17 00:29:28 2007 @@ -7,6 +7,9 @@ * __u32 len, * unsigned short proto, * unsigned int csum); + * + * Misalignment handling (which costs 16 instructions / 8 cycles) + * added by Ivan Kokshaysky <ink@...assic.park.msu.ru> */ .globl csum_ipv6_magic @@ -16,37 +19,57 @@ csum_ipv6_magic: .prologue 0 - ldq $0,0($16) # e0 : load src & dst addr words + ldq_u $0,0($16) # e0 : load src & dst addr words zapnot $20,15,$20 # .. e1 : zero extend incoming csum extqh $18,1,$4 # e0 : byte swap len & proto while we wait - ldq $1,8($16) # .. e1 : + ldq_u $21,7($16) # .. e1 : handle misalignment extbl $18,1,$5 # e0 : - ldq $2,0($17) # .. e1 : + ldq_u $1,8($16) # .. e1 : extbl $18,2,$6 # e0 : - ldq $3,8($17) # .. e1 : + ldq_u $22,15($16) # .. e1 : extbl $18,3,$18 # e0 : + ldq_u $2,0($17) # .. e1 : sra $4,32,$4 # e0 : + ldq_u $23,7($17) # .. e1 : + + extql $0,$16,$0 # e0 : + ldq_u $3,8($17) # .. e1 : + extqh $21,$16,$21 # e0 : + ldq_u $24,15($17) # .. e1 : + sll $5,16,$5 # e0 : + or $0,$21,$0 # .. e1 : 1st src word complete + extql $1,$16,$1 # e0 : addq $20,$0,$20 # .. e1 : begin summing the words - sll $6,8,$6 # e0 : + extqh $22,$16,$22 # e0 : cmpult $20,$0,$0 # .. e1 : - extwh $19,7,$7 # e0 : - or $4,$18,$18 # .. e1 : + sll $6,8,$6 # e0 : + or $1,$22,$1 # .. e1 : 2nd src word complete - extbl $19,1,$19 # e0 : + extql $2,$17,$2 # e0 : + or $4,$18,$18 # .. e1 : + extqh $23,$17,$23 # e0 : or $5,$6,$5 # .. e1 : - or $18,$5,$18 # e0 : len complete - or $19,$7,$19 # .. e1 : - sll $19,48,$19 # e0 : + extql $3,$17,$3 # e0 : + or $2,$23,$2 # .. e1 : 1st dst word complete + extqh $24,$17,$24 # e0 : + or $18,$5,$18 # .. e1 : len complete + + extwh $19,7,$7 # e0 : + or $3,$24,$3 # .. e1 : 2nd dst word complete + extbl $19,1,$19 # e0 : addq $20,$1,$20 # .. e1 : - sra $19,32,$19 # e0 : proto complete + + or $19,$7,$19 # e0 : cmpult $20,$1,$1 # .. e1 : + sll $19,48,$19 # e0 : + nop # .. e0 : - nop # e0 : + sra $19,32,$19 # e0 : proto complete addq $20,$2,$20 # .. e1 : cmpult $20,$2,$2 # e0 : addq $20,$3,$20 # .. e1 : @@ -84,7 +107,7 @@ csum_ipv6_magic: extwl $0,2,$1 # e0 : fold 17-bit value zapnot $0,3,$0 # .. e1 : addq $0,$1,$0 # e0 : - not $0,$0 # e1 : and complement. + not $0,$0 # .. e1 : and complement. zapnot $0,3,$0 # e0 : ret # .. e1 : - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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