mirror of
https://github.com/torvalds/linux.git
synced 2024-11-18 01:51:53 +00:00
58ed2f9c75
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>
151 lines
5.1 KiB
ArmAsm
151 lines
5.1 KiB
ArmAsm
/*
|
|
* arch/alpha/lib/ev6-csum_ipv6_magic.S
|
|
* 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
|
|
*
|
|
* unsigned short csum_ipv6_magic(struct in6_addr *saddr,
|
|
* struct in6_addr *daddr,
|
|
* __u32 len,
|
|
* unsigned short proto,
|
|
* unsigned int csum);
|
|
*
|
|
* Much of the information about 21264 scheduling/coding comes from:
|
|
* Compiler Writer's Guide for the Alpha 21264
|
|
* abbreviated as 'CWG' in other comments here
|
|
* ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
|
|
* Scheduling notation:
|
|
* E - either cluster
|
|
* U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
|
|
* L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
|
|
* Try not to change the actual algorithm if possible for consistency.
|
|
* Determining actual stalls (other than slotting) doesn't appear to be easy to do.
|
|
*
|
|
* unsigned short csum_ipv6_magic(struct in6_addr *saddr,
|
|
* struct in6_addr *daddr,
|
|
* __u32 len,
|
|
* unsigned short proto,
|
|
* unsigned int csum);
|
|
*
|
|
* Swap <proto> (takes form 0xaabb)
|
|
* Then shift it left by 48, so result is:
|
|
* 0xbbaa0000 00000000
|
|
* Then turn it back into a sign extended 32-bit item
|
|
* 0xbbaa0000
|
|
*
|
|
* Swap <len> (an unsigned int) using Mike Burrows' 7-instruction sequence
|
|
* (we can't hide the 3-cycle latency of the unpkbw in the 6-instruction sequence)
|
|
* Assume input takes form 0xAABBCCDD
|
|
*
|
|
* Finally, original 'folding' approach is to split the long into 4 unsigned shorts
|
|
* add 4 ushorts, resulting in ushort/carry
|
|
* add carry bits + ushort --> ushort
|
|
* add carry bits + ushort --> ushort (in case the carry results in an overflow)
|
|
* Truncate to a ushort. (took 13 instructions)
|
|
* From doing some testing, using the approach in checksum.c:from64to16()
|
|
* results in the same outcome:
|
|
* split into 2 uints, add those, generating a ulong
|
|
* 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
|
|
.align 4
|
|
.ent csum_ipv6_magic
|
|
.frame $30,0,$26,0
|
|
csum_ipv6_magic:
|
|
.prologue 0
|
|
|
|
ldq_u $0,0($16) # L : Latency: 3
|
|
inslh $18,7,$4 # U : 0000000000AABBCC
|
|
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_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
|
|
|
|
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
|
|
or $3,$23,$3 # E : U L U L : 2nd dst word complete
|
|
|
|
cmpult $20,$0,$0 # E :
|
|
addq $20,$1,$20 # E :
|
|
zapnot $18,0xa,$18 # U : 00000000DD00BB00
|
|
zap $4,0xa,$4 # U : U U L L : 0000000000CC00AA
|
|
|
|
or $18,$4,$18 # E : 00000000DDCCBBAA
|
|
nop # E :
|
|
cmpult $20,$1,$1 # E :
|
|
addq $20,$2,$20 # E : U L U L
|
|
|
|
cmpult $20,$2,$2 # E :
|
|
addq $20,$3,$20 # E :
|
|
cmpult $20,$3,$3 # E : (1 cycle stall on $20)
|
|
addq $20,$18,$20 # E : U L U L (1 cycle stall on $20)
|
|
|
|
cmpult $20,$18,$18 # E :
|
|
addq $20,$19,$20 # E : (1 cycle stall on $20)
|
|
addq $0,$1,$0 # E : merge the carries back into the csum
|
|
addq $2,$3,$2 # E :
|
|
|
|
cmpult $20,$19,$19 # E :
|
|
addq $18,$19,$18 # E : (1 cycle stall on $19)
|
|
addq $0,$2,$0 # E :
|
|
addq $20,$18,$20 # E : U L U L :
|
|
/* (1 cycle stall on $18, 2 cycles on $20) */
|
|
|
|
addq $0,$20,$0 # E :
|
|
zapnot $0,15,$1 # U : Start folding output (1 cycle stall on $0)
|
|
nop # E :
|
|
srl $0,32,$0 # U : U L U L : (1 cycle stall on $0)
|
|
|
|
addq $1,$0,$1 # E : Finished generating ulong
|
|
extwl $1,2,$2 # U : ushort[1] (1 cycle stall on $1)
|
|
zapnot $1,3,$0 # U : ushort[0] (1 cycle stall on $1)
|
|
extwl $1,4,$1 # U : ushort[2] (1 cycle stall on $1)
|
|
|
|
addq $0,$2,$0 # E
|
|
addq $0,$1,$3 # E : Finished generating uint
|
|
/* (1 cycle stall on $0) */
|
|
extwl $3,2,$1 # U : ushort[1] (1 cycle stall on $3)
|
|
nop # E : L U L U
|
|
|
|
addq $1,$3,$0 # E : Final carry
|
|
not $0,$4 # E : complement (1 cycle stall on $0)
|
|
zapnot $4,3,$0 # U : clear upper garbage bits
|
|
/* (1 cycle stall on $4) */
|
|
ret # L0 : L U L U
|
|
|
|
.end csum_ipv6_magic
|