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linux/arch/mips/lib/csum_partial.S
Atsushi Nemoto f860c90bd6 [MIPS] csum_partial and copy in parallel 
Implement optimized asm version of csum_partial_copy_nocheck,
csum_partial_copy_from_user and csum_and_copy_to_user which can do
calculate and copy in parallel, based on memcpy.S.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-01-08 21:41:04 +00:00

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Quick'n'dirty IP checksum ...
*
* Copyright (C) 1998, 1999 Ralf Baechle
* Copyright (C) 1999 Silicon Graphics, Inc.
*/
#include <linux/errno.h>
#include <asm/asm.h>
#include <asm/asm-offsets.h>
#include <asm/regdef.h>
#ifdef CONFIG_64BIT
/*
* As we are sharing code base with the mips32 tree (which use the o32 ABI
* register definitions). We need to redefine the register definitions from
* the n64 ABI register naming to the o32 ABI register naming.
*/
#undef t0
#undef t1
#undef t2
#undef t3
#define t0 $8
#define t1 $9
#define t2 $10
#define t3 $11
#define t4 $12
#define t5 $13
#define t6 $14
#define t7 $15
#define USE_DOUBLE
#endif
#ifdef USE_DOUBLE
#define LOAD ld
#define ADD daddu
#define NBYTES 8
#else
#define LOAD lw
#define ADD addu
#define NBYTES 4
#endif /* USE_DOUBLE */
#define UNIT(unit) ((unit)*NBYTES)
#define ADDC(sum,reg) \
ADD sum, reg; \
sltu v1, sum, reg; \
ADD sum, v1
#define CSUM_BIGCHUNK1(src, offset, sum, _t0, _t1, _t2, _t3) \
LOAD _t0, (offset + UNIT(0))(src); \
LOAD _t1, (offset + UNIT(1))(src); \
LOAD _t2, (offset + UNIT(2))(src); \
LOAD _t3, (offset + UNIT(3))(src); \
ADDC(sum, _t0); \
ADDC(sum, _t1); \
ADDC(sum, _t2); \
ADDC(sum, _t3)
#ifdef USE_DOUBLE
#define CSUM_BIGCHUNK(src, offset, sum, _t0, _t1, _t2, _t3) \
CSUM_BIGCHUNK1(src, offset, sum, _t0, _t1, _t2, _t3)
#else
#define CSUM_BIGCHUNK(src, offset, sum, _t0, _t1, _t2, _t3) \
CSUM_BIGCHUNK1(src, offset, sum, _t0, _t1, _t2, _t3); \
CSUM_BIGCHUNK1(src, offset + 0x10, sum, _t0, _t1, _t2, _t3)
#endif
/*
* a0: source address
* a1: length of the area to checksum
* a2: partial checksum
*/
#define src a0
#define sum v0
.text
.set noreorder
.align 5
LEAF(csum_partial)
move sum, zero
move t7, zero
sltiu t8, a1, 0x8
bnez t8, small_csumcpy /* < 8 bytes to copy */
move t2, a1
andi t7, src, 0x1 /* odd buffer? */
hword_align:
beqz t7, word_align
andi t8, src, 0x2
lbu t0, (src)
LONG_SUBU a1, a1, 0x1
#ifdef __MIPSEL__
sll t0, t0, 8
#endif
ADDC(sum, t0)
PTR_ADDU src, src, 0x1
andi t8, src, 0x2
word_align:
beqz t8, dword_align
sltiu t8, a1, 56
lhu t0, (src)
LONG_SUBU a1, a1, 0x2
ADDC(sum, t0)
sltiu t8, a1, 56
PTR_ADDU src, src, 0x2
dword_align:
bnez t8, do_end_words
move t8, a1
andi t8, src, 0x4
beqz t8, qword_align
andi t8, src, 0x8
lw t0, 0x00(src)
LONG_SUBU a1, a1, 0x4
ADDC(sum, t0)
PTR_ADDU src, src, 0x4
andi t8, src, 0x8
qword_align:
beqz t8, oword_align
andi t8, src, 0x10
#ifdef USE_DOUBLE
ld t0, 0x00(src)
LONG_SUBU a1, a1, 0x8
ADDC(sum, t0)
#else
lw t0, 0x00(src)
lw t1, 0x04(src)
LONG_SUBU a1, a1, 0x8
ADDC(sum, t0)
ADDC(sum, t1)
#endif
PTR_ADDU src, src, 0x8
andi t8, src, 0x10
oword_align:
beqz t8, begin_movement
LONG_SRL t8, a1, 0x7
#ifdef USE_DOUBLE
ld t0, 0x00(src)
ld t1, 0x08(src)
ADDC(sum, t0)
ADDC(sum, t1)
#else
CSUM_BIGCHUNK1(src, 0x00, sum, t0, t1, t3, t4)
#endif
LONG_SUBU a1, a1, 0x10
PTR_ADDU src, src, 0x10
LONG_SRL t8, a1, 0x7
begin_movement:
beqz t8, 1f
andi t2, a1, 0x40
move_128bytes:
CSUM_BIGCHUNK(src, 0x00, sum, t0, t1, t3, t4)
CSUM_BIGCHUNK(src, 0x20, sum, t0, t1, t3, t4)
CSUM_BIGCHUNK(src, 0x40, sum, t0, t1, t3, t4)
CSUM_BIGCHUNK(src, 0x60, sum, t0, t1, t3, t4)
LONG_SUBU t8, t8, 0x01
bnez t8, move_128bytes
PTR_ADDU src, src, 0x80
1:
beqz t2, 1f
andi t2, a1, 0x20
move_64bytes:
CSUM_BIGCHUNK(src, 0x00, sum, t0, t1, t3, t4)
CSUM_BIGCHUNK(src, 0x20, sum, t0, t1, t3, t4)
PTR_ADDU src, src, 0x40
1:
beqz t2, do_end_words
andi t8, a1, 0x1c
move_32bytes:
CSUM_BIGCHUNK(src, 0x00, sum, t0, t1, t3, t4)
andi t8, a1, 0x1c
PTR_ADDU src, src, 0x20
do_end_words:
beqz t8, small_csumcpy
andi t2, a1, 0x3
LONG_SRL t8, t8, 0x2
end_words:
lw t0, (src)
LONG_SUBU t8, t8, 0x1
ADDC(sum, t0)
bnez t8, end_words
PTR_ADDU src, src, 0x4
/* unknown src alignment and < 8 bytes to go */
small_csumcpy:
move a1, t2
andi t0, a1, 4
beqz t0, 1f
andi t0, a1, 2
/* Still a full word to go */
ulw t1, (src)
PTR_ADDIU src, 4
ADDC(sum, t1)
1: move t1, zero
beqz t0, 1f
andi t0, a1, 1
/* Still a halfword to go */
ulhu t1, (src)
PTR_ADDIU src, 2
1: beqz t0, 1f
sll t1, t1, 16
lbu t2, (src)
nop
#ifdef __MIPSEB__
sll t2, t2, 8
#endif
or t1, t2
1: ADDC(sum, t1)
/* fold checksum */
#ifdef USE_DOUBLE
dsll32 v1, sum, 0
daddu sum, v1
sltu v1, sum, v1
dsra32 sum, sum, 0
addu sum, v1
#endif
sll v1, sum, 16
addu sum, v1
sltu v1, sum, v1
srl sum, sum, 16
addu sum, v1
/* odd buffer alignment? */
beqz t7, 1f
nop
sll v1, sum, 8
srl sum, sum, 8
or sum, v1
andi sum, 0xffff
1:
.set reorder
/* Add the passed partial csum. */
ADDC(sum, a2)
jr ra
.set noreorder
END(csum_partial)
/*
* checksum and copy routines based on memcpy.S
*
* csum_partial_copy_nocheck(src, dst, len, sum)
* __csum_partial_copy_user(src, dst, len, sum, errp)
*
* See "Spec" in memcpy.S for details. Unlike __copy_user, all
* function in this file use the standard calling convention.
*/
#define src a0
#define dst a1
#define len a2
#define psum a3
#define sum v0
#define odd t8
#define errptr t9
/*
* The exception handler for loads requires that:
* 1- AT contain the address of the byte just past the end of the source
* of the copy,
* 2- src_entry <= src < AT, and
* 3- (dst - src) == (dst_entry - src_entry),
* The _entry suffix denotes values when __copy_user was called.
*
* (1) is set up up by __csum_partial_copy_from_user and maintained by
* not writing AT in __csum_partial_copy
* (2) is met by incrementing src by the number of bytes copied
* (3) is met by not doing loads between a pair of increments of dst and src
*
* The exception handlers for stores stores -EFAULT to errptr and return.
* These handlers do not need to overwrite any data.
*/
#define EXC(inst_reg,addr,handler) \
9: inst_reg, addr; \
.section __ex_table,"a"; \
PTR 9b, handler; \
.previous
#ifdef USE_DOUBLE
#define LOAD ld
#define LOADL ldl
#define LOADR ldr
#define STOREL sdl
#define STORER sdr
#define STORE sd
#define ADD daddu
#define SUB dsubu
#define SRL dsrl
#define SLL dsll
#define SLLV dsllv
#define SRLV dsrlv
#define NBYTES 8
#define LOG_NBYTES 3
#else
#define LOAD lw
#define LOADL lwl
#define LOADR lwr
#define STOREL swl
#define STORER swr
#define STORE sw
#define ADD addu
#define SUB subu
#define SRL srl
#define SLL sll
#define SLLV sllv
#define SRLV srlv
#define NBYTES 4
#define LOG_NBYTES 2
#endif /* USE_DOUBLE */
#ifdef CONFIG_CPU_LITTLE_ENDIAN
#define LDFIRST LOADR
#define LDREST LOADL
#define STFIRST STORER
#define STREST STOREL
#define SHIFT_DISCARD SLLV
#define SHIFT_DISCARD_REVERT SRLV
#else
#define LDFIRST LOADL
#define LDREST LOADR
#define STFIRST STOREL
#define STREST STORER
#define SHIFT_DISCARD SRLV
#define SHIFT_DISCARD_REVERT SLLV
#endif
#define FIRST(unit) ((unit)*NBYTES)
#define REST(unit) (FIRST(unit)+NBYTES-1)
#define ADDRMASK (NBYTES-1)
.set noat
LEAF(__csum_partial_copy_user)
PTR_ADDU AT, src, len /* See (1) above. */
#ifdef CONFIG_64BIT
move errptr, a4
#else
lw errptr, 16(sp)
#endif
FEXPORT(csum_partial_copy_nocheck)
move sum, zero
move odd, zero
/*
* Note: dst & src may be unaligned, len may be 0
* Temps
*/
/*
* The "issue break"s below are very approximate.
* Issue delays for dcache fills will perturb the schedule, as will
* load queue full replay traps, etc.
*
* If len < NBYTES use byte operations.
*/
sltu t2, len, NBYTES
and t1, dst, ADDRMASK
bnez t2, copy_bytes_checklen
and t0, src, ADDRMASK
andi odd, dst, 0x1 /* odd buffer? */
bnez t1, dst_unaligned
nop
bnez t0, src_unaligned_dst_aligned
/*
* use delay slot for fall-through
* src and dst are aligned; need to compute rem
*/
both_aligned:
SRL t0, len, LOG_NBYTES+3 # +3 for 8 units/iter
beqz t0, cleanup_both_aligned # len < 8*NBYTES
nop
SUB len, 8*NBYTES # subtract here for bgez loop
.align 4
1:
EXC( LOAD t0, UNIT(0)(src), l_exc)
EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
EXC( LOAD t4, UNIT(4)(src), l_exc_copy)
EXC( LOAD t5, UNIT(5)(src), l_exc_copy)
EXC( LOAD t6, UNIT(6)(src), l_exc_copy)
EXC( LOAD t7, UNIT(7)(src), l_exc_copy)
SUB len, len, 8*NBYTES
ADD src, src, 8*NBYTES
EXC( STORE t0, UNIT(0)(dst), s_exc)
ADDC(sum, t0)
EXC( STORE t1, UNIT(1)(dst), s_exc)
ADDC(sum, t1)
EXC( STORE t2, UNIT(2)(dst), s_exc)
ADDC(sum, t2)
EXC( STORE t3, UNIT(3)(dst), s_exc)
ADDC(sum, t3)
EXC( STORE t4, UNIT(4)(dst), s_exc)
ADDC(sum, t4)
EXC( STORE t5, UNIT(5)(dst), s_exc)
ADDC(sum, t5)
EXC( STORE t6, UNIT(6)(dst), s_exc)
ADDC(sum, t6)
EXC( STORE t7, UNIT(7)(dst), s_exc)
ADDC(sum, t7)
bgez len, 1b
ADD dst, dst, 8*NBYTES
ADD len, 8*NBYTES # revert len (see above)
/*
* len == the number of bytes left to copy < 8*NBYTES
*/
cleanup_both_aligned:
#define rem t7
beqz len, done
sltu t0, len, 4*NBYTES
bnez t0, less_than_4units
and rem, len, (NBYTES-1) # rem = len % NBYTES
/*
* len >= 4*NBYTES
*/
EXC( LOAD t0, UNIT(0)(src), l_exc)
EXC( LOAD t1, UNIT(1)(src), l_exc_copy)
EXC( LOAD t2, UNIT(2)(src), l_exc_copy)
EXC( LOAD t3, UNIT(3)(src), l_exc_copy)
SUB len, len, 4*NBYTES
ADD src, src, 4*NBYTES
EXC( STORE t0, UNIT(0)(dst), s_exc)
ADDC(sum, t0)
EXC( STORE t1, UNIT(1)(dst), s_exc)
ADDC(sum, t1)
EXC( STORE t2, UNIT(2)(dst), s_exc)
ADDC(sum, t2)
EXC( STORE t3, UNIT(3)(dst), s_exc)
ADDC(sum, t3)
beqz len, done
ADD dst, dst, 4*NBYTES
less_than_4units:
/*
* rem = len % NBYTES
*/
beq rem, len, copy_bytes
nop
1:
EXC( LOAD t0, 0(src), l_exc)
ADD src, src, NBYTES
SUB len, len, NBYTES
EXC( STORE t0, 0(dst), s_exc)
ADDC(sum, t0)
bne rem, len, 1b
ADD dst, dst, NBYTES
/*
* src and dst are aligned, need to copy rem bytes (rem < NBYTES)
* A loop would do only a byte at a time with possible branch
* mispredicts. Can't do an explicit LOAD dst,mask,or,STORE
* because can't assume read-access to dst. Instead, use
* STREST dst, which doesn't require read access to dst.
*
* This code should perform better than a simple loop on modern,
* wide-issue mips processors because the code has fewer branches and
* more instruction-level parallelism.
*/
#define bits t2
beqz len, done
ADD t1, dst, len # t1 is just past last byte of dst
li bits, 8*NBYTES
SLL rem, len, 3 # rem = number of bits to keep
EXC( LOAD t0, 0(src), l_exc)
SUB bits, bits, rem # bits = number of bits to discard
SHIFT_DISCARD t0, t0, bits
EXC( STREST t0, -1(t1), s_exc)
SHIFT_DISCARD_REVERT t0, t0, bits
.set reorder
ADDC(sum, t0)
b done
.set noreorder
dst_unaligned:
/*
* dst is unaligned
* t0 = src & ADDRMASK
* t1 = dst & ADDRMASK; T1 > 0
* len >= NBYTES
*
* Copy enough bytes to align dst
* Set match = (src and dst have same alignment)
*/
#define match rem
EXC( LDFIRST t3, FIRST(0)(src), l_exc)
ADD t2, zero, NBYTES
EXC( LDREST t3, REST(0)(src), l_exc_copy)
SUB t2, t2, t1 # t2 = number of bytes copied
xor match, t0, t1
EXC( STFIRST t3, FIRST(0)(dst), s_exc)
SLL t4, t1, 3 # t4 = number of bits to discard
SHIFT_DISCARD t3, t3, t4
/* no SHIFT_DISCARD_REVERT to handle odd buffer properly */
ADDC(sum, t3)
beq len, t2, done
SUB len, len, t2
ADD dst, dst, t2
beqz match, both_aligned
ADD src, src, t2
src_unaligned_dst_aligned:
SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter
beqz t0, cleanup_src_unaligned
and rem, len, (4*NBYTES-1) # rem = len % 4*NBYTES
1:
/*
* Avoid consecutive LD*'s to the same register since some mips
* implementations can't issue them in the same cycle.
* It's OK to load FIRST(N+1) before REST(N) because the two addresses
* are to the same unit (unless src is aligned, but it's not).
*/
EXC( LDFIRST t0, FIRST(0)(src), l_exc)
EXC( LDFIRST t1, FIRST(1)(src), l_exc_copy)
SUB len, len, 4*NBYTES
EXC( LDREST t0, REST(0)(src), l_exc_copy)
EXC( LDREST t1, REST(1)(src), l_exc_copy)
EXC( LDFIRST t2, FIRST(2)(src), l_exc_copy)
EXC( LDFIRST t3, FIRST(3)(src), l_exc_copy)
EXC( LDREST t2, REST(2)(src), l_exc_copy)
EXC( LDREST t3, REST(3)(src), l_exc_copy)
ADD src, src, 4*NBYTES
#ifdef CONFIG_CPU_SB1
nop # improves slotting
#endif
EXC( STORE t0, UNIT(0)(dst), s_exc)
ADDC(sum, t0)
EXC( STORE t1, UNIT(1)(dst), s_exc)
ADDC(sum, t1)
EXC( STORE t2, UNIT(2)(dst), s_exc)
ADDC(sum, t2)
EXC( STORE t3, UNIT(3)(dst), s_exc)
ADDC(sum, t3)
bne len, rem, 1b
ADD dst, dst, 4*NBYTES
cleanup_src_unaligned:
beqz len, done
and rem, len, NBYTES-1 # rem = len % NBYTES
beq rem, len, copy_bytes
nop
1:
EXC( LDFIRST t0, FIRST(0)(src), l_exc)
EXC( LDREST t0, REST(0)(src), l_exc_copy)
ADD src, src, NBYTES
SUB len, len, NBYTES
EXC( STORE t0, 0(dst), s_exc)
ADDC(sum, t0)
bne len, rem, 1b
ADD dst, dst, NBYTES
copy_bytes_checklen:
beqz len, done
nop
copy_bytes:
/* 0 < len < NBYTES */
#ifdef CONFIG_CPU_LITTLE_ENDIAN
#define SHIFT_START 0
#define SHIFT_INC 8
#else
#define SHIFT_START 8*(NBYTES-1)
#define SHIFT_INC -8
#endif
move t2, zero # partial word
li t3, SHIFT_START # shift
/* use l_exc_copy here to return correct sum on fault */
#define COPY_BYTE(N) \
EXC( lbu t0, N(src), l_exc_copy); \
SUB len, len, 1; \
EXC( sb t0, N(dst), s_exc); \
SLLV t0, t0, t3; \
addu t3, SHIFT_INC; \
beqz len, copy_bytes_done; \
or t2, t0
COPY_BYTE(0)
COPY_BYTE(1)
#ifdef USE_DOUBLE
COPY_BYTE(2)
COPY_BYTE(3)
COPY_BYTE(4)
COPY_BYTE(5)
#endif
EXC( lbu t0, NBYTES-2(src), l_exc_copy)
SUB len, len, 1
EXC( sb t0, NBYTES-2(dst), s_exc)
SLLV t0, t0, t3
or t2, t0
copy_bytes_done:
ADDC(sum, t2)
done:
/* fold checksum */
#ifdef USE_DOUBLE
dsll32 v1, sum, 0
daddu sum, v1
sltu v1, sum, v1
dsra32 sum, sum, 0
addu sum, v1
#endif
sll v1, sum, 16
addu sum, v1
sltu v1, sum, v1
srl sum, sum, 16
addu sum, v1
/* odd buffer alignment? */
beqz odd, 1f
nop
sll v1, sum, 8
srl sum, sum, 8
or sum, v1
andi sum, 0xffff
1:
.set reorder
ADDC(sum, psum)
jr ra
.set noreorder
l_exc_copy:
/*
* Copy bytes from src until faulting load address (or until a
* lb faults)
*
* When reached by a faulting LDFIRST/LDREST, THREAD_BUADDR($28)
* may be more than a byte beyond the last address.
* Hence, the lb below may get an exception.
*
* Assumes src < THREAD_BUADDR($28)
*/
LOAD t0, TI_TASK($28)
li t2, SHIFT_START
LOAD t0, THREAD_BUADDR(t0)
1:
EXC( lbu t1, 0(src), l_exc)
ADD src, src, 1
sb t1, 0(dst) # can't fault -- we're copy_from_user
SLLV t1, t1, t2
addu t2, SHIFT_INC
ADDC(sum, t1)
bne src, t0, 1b
ADD dst, dst, 1
l_exc:
LOAD t0, TI_TASK($28)
nop
LOAD t0, THREAD_BUADDR(t0) # t0 is just past last good address
nop
SUB len, AT, t0 # len number of uncopied bytes
/*
* Here's where we rely on src and dst being incremented in tandem,
* See (3) above.
* dst += (fault addr - src) to put dst at first byte to clear
*/
ADD dst, t0 # compute start address in a1
SUB dst, src
/*
* Clear len bytes starting at dst. Can't call __bzero because it
* might modify len. An inefficient loop for these rare times...
*/
beqz len, done
SUB src, len, 1
1: sb zero, 0(dst)
ADD dst, dst, 1
bnez src, 1b
SUB src, src, 1
li v1, -EFAULT
b done
sw v1, (errptr)
s_exc:
li v0, -1 /* invalid checksum */
li v1, -EFAULT
jr ra
sw v1, (errptr)
END(__csum_partial_copy_user)
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