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kernel-fxtec-pro1x/arch/mips/lib/csum_partial.S
Chen Jie 615eb603f4 MIPS: csum_partial: Improve instruction parallelism. 
Computing sum introduces true data dependency. This patch removes some
true data depdendencies, hence increases instruction level parallelism.

This patch brings up to 50% csum performance gain on Loongson 3a.

One example about how this patch works is in CSUM_BIGCHUNK1:
// ** original **    vs    ** patch applied **
    ADDC(sum, t0)           ADDC(t0, t1)
    ADDC(sum, t1)           ADDC(t2, t3)
    ADDC(sum, t2)           ADDC(sum, t0)
    ADDC(sum, t3)           ADDC(sum, t2)

In the original implementation, each ADDC(sum, ...) depends on the sum
value updated by previous ADDC(as source operand).

With this patch applied, the first two ADDC operations are independent,
hence can be executed simultaneously if possible.

Another example is in the "copy and sum calculating chunk":
// ** original **    vs    ** patch applied **
    STORE(t0, UNIT(0) ...   STORE(t0, UNIT(0) ...
    ADDC(sum, t0)           ADDC(t0, t1)
    STORE(t1, UNIT(1) ...   STORE(t1, UNIT(1) ...
    ADDC(sum, t1)           ADDC(sum, t0)
    STORE(t2, UNIT(2) ...   STORE(t2, UNIT(2) ...
    ADDC(sum, t2)           ADDC(t2, t3)
    STORE(t3, UNIT(3) ...   STORE(t3, UNIT(3) ...
    ADDC(sum, t3)           ADDC(sum, t2)

With this patch applied, ADDC and the **next next** ADDC are independent.

Signed-off-by: chenj <chenj@lemote.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9608/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-04-01 17:22:11 +02:00

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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.
* Copyright (C) 2007 Maciej W. Rozycki
* Copyright (C) 2014 Imagination Technologies Ltd.
*/
#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 LOAD32 lwu
#define ADD daddu
#define NBYTES 8
#else
#define LOAD lw
#define LOAD32 lw
#define ADD addu
#define NBYTES 4
#endif /* USE_DOUBLE */
#define UNIT(unit) ((unit)*NBYTES)
#define ADDC(sum,reg) \
.set push; \
.set noat; \
ADD sum, reg; \
sltu v1, sum, reg; \
ADD sum, v1; \
.set pop
#define ADDC32(sum,reg) \
.set push; \
.set noat; \
addu sum, reg; \
sltu v1, sum, reg; \
addu sum, v1; \
.set pop
#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(_t0, _t1); \
ADDC(_t2, _t3); \
ADDC(sum, _t0); \
ADDC(sum, _t2)
#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, .Lsmall_csumcpy /* < 8 bytes to copy */
move t2, a1
andi t7, src, 0x1 /* odd buffer? */
.Lhword_align:
beqz t7, .Lword_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
.Lword_align:
beqz t8, .Ldword_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
.Ldword_align:
bnez t8, .Ldo_end_words
move t8, a1
andi t8, src, 0x4
beqz t8, .Lqword_align
andi t8, src, 0x8
LOAD32 t0, 0x00(src)
LONG_SUBU a1, a1, 0x4
ADDC(sum, t0)
PTR_ADDU src, src, 0x4
andi t8, src, 0x8
.Lqword_align:
beqz t8, .Loword_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
.Loword_align:
beqz t8, .Lbegin_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
.Lbegin_movement:
beqz t8, 1f
andi t2, a1, 0x40
.Lmove_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
.set reorder /* DADDI_WAR */
PTR_ADDU src, src, 0x80
bnez t8, .Lmove_128bytes
.set noreorder
1:
beqz t2, 1f
andi t2, a1, 0x20
.Lmove_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, .Ldo_end_words
andi t8, a1, 0x1c
.Lmove_32bytes:
CSUM_BIGCHUNK(src, 0x00, sum, t0, t1, t3, t4)
andi t8, a1, 0x1c
PTR_ADDU src, src, 0x20
.Ldo_end_words:
beqz t8, .Lsmall_csumcpy
andi t2, a1, 0x3
LONG_SRL t8, t8, 0x2
.Lend_words:
LOAD32 t0, (src)
LONG_SUBU t8, t8, 0x1
ADDC(sum, t0)
.set reorder /* DADDI_WAR */
PTR_ADDU src, src, 0x4
bnez t8, .Lend_words
.set noreorder
/* unknown src alignment and < 8 bytes to go */
.Lsmall_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
#ifdef USE_DOUBLE
dsll t1, t1, 32 /* clear lower 32bit */
#endif
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
/* odd buffer alignment? */
#if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_LOONGSON3)
.set push
.set arch=mips32r2
wsbh v1, sum
movn sum, v1, t7
.set pop
#else
beqz t7, 1f /* odd buffer alignment? */
lui v1, 0x00ff
addu v1, 0x00ff
and t0, sum, v1
sll t0, t0, 8
srl sum, sum, 8
and sum, sum, v1
or sum, sum, t0
1:
#endif
.set reorder
/* Add the passed partial csum. */
ADDC32(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_kernel(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.
*/
/* Instruction type */
#define LD_INSN 1
#define ST_INSN 2
#define LEGACY_MODE 1
#define EVA_MODE 2
#define USEROP 1
#define KERNELOP 2
/*
* Wrapper to add an entry in the exception table
* in case the insn causes a memory exception.
* Arguments:
* insn : Load/store instruction
* type : Instruction type
* reg : Register
* addr : Address
* handler : Exception handler
*/
#define EXC(insn, type, reg, addr, handler) \
.if \mode == LEGACY_MODE; \
9: insn reg, addr; \
.section __ex_table,"a"; \
PTR 9b, handler; \
.previous; \
/* This is enabled in EVA mode */ \
.else; \
/* If loading from user or storing to user */ \
.if ((\from == USEROP) && (type == LD_INSN)) || \
((\to == USEROP) && (type == ST_INSN)); \
9: __BUILD_EVA_INSN(insn##e, reg, addr); \
.section __ex_table,"a"; \
PTR 9b, handler; \
.previous; \
.else; \
/* EVA without exception */ \
insn reg, addr; \
.endif; \
.endif
#undef LOAD
#ifdef USE_DOUBLE
#define LOADK ld /* No exception */
#define LOAD(reg, addr, handler) EXC(ld, LD_INSN, reg, addr, handler)
#define LOADBU(reg, addr, handler) EXC(lbu, LD_INSN, reg, addr, handler)
#define LOADL(reg, addr, handler) EXC(ldl, LD_INSN, reg, addr, handler)
#define LOADR(reg, addr, handler) EXC(ldr, LD_INSN, reg, addr, handler)
#define STOREB(reg, addr, handler) EXC(sb, ST_INSN, reg, addr, handler)
#define STOREL(reg, addr, handler) EXC(sdl, ST_INSN, reg, addr, handler)
#define STORER(reg, addr, handler) EXC(sdr, ST_INSN, reg, addr, handler)
#define STORE(reg, addr, handler) EXC(sd, ST_INSN, reg, addr, handler)
#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 LOADK lw /* No exception */
#define LOAD(reg, addr, handler) EXC(lw, LD_INSN, reg, addr, handler)
#define LOADBU(reg, addr, handler) EXC(lbu, LD_INSN, reg, addr, handler)
#define LOADL(reg, addr, handler) EXC(lwl, LD_INSN, reg, addr, handler)
#define LOADR(reg, addr, handler) EXC(lwr, LD_INSN, reg, addr, handler)
#define STOREB(reg, addr, handler) EXC(sb, ST_INSN, reg, addr, handler)
#define STOREL(reg, addr, handler) EXC(swl, ST_INSN, reg, addr, handler)
#define STORER(reg, addr, handler) EXC(swr, ST_INSN, reg, addr, handler)
#define STORE(reg, addr, handler) EXC(sw, ST_INSN, reg, addr, handler)
#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)
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
.set noat
#else
.set at=v1
#endif
.macro __BUILD_CSUM_PARTIAL_COPY_USER mode, from, to, __nocheck
PTR_ADDU AT, src, len /* See (1) above. */
/* initialize __nocheck if this the first time we execute this
* macro
*/
#ifdef CONFIG_64BIT
move errptr, a4
#else
lw errptr, 16(sp)
#endif
.if \__nocheck == 1
FEXPORT(csum_partial_copy_nocheck)
.endif
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, .Lcopy_bytes_checklen\@
and t0, src, ADDRMASK
andi odd, dst, 0x1 /* odd buffer? */
bnez t1, .Ldst_unaligned\@
nop
bnez t0, .Lsrc_unaligned_dst_aligned\@
/*
* use delay slot for fall-through
* src and dst are aligned; need to compute rem
*/
.Lboth_aligned\@:
SRL t0, len, LOG_NBYTES+3 # +3 for 8 units/iter
beqz t0, .Lcleanup_both_aligned\@ # len < 8*NBYTES
nop
SUB len, 8*NBYTES # subtract here for bgez loop
.align 4
1:
LOAD(t0, UNIT(0)(src), .Ll_exc\@)
LOAD(t1, UNIT(1)(src), .Ll_exc_copy\@)
LOAD(t2, UNIT(2)(src), .Ll_exc_copy\@)
LOAD(t3, UNIT(3)(src), .Ll_exc_copy\@)
LOAD(t4, UNIT(4)(src), .Ll_exc_copy\@)
LOAD(t5, UNIT(5)(src), .Ll_exc_copy\@)
LOAD(t6, UNIT(6)(src), .Ll_exc_copy\@)
LOAD(t7, UNIT(7)(src), .Ll_exc_copy\@)
SUB len, len, 8*NBYTES
ADD src, src, 8*NBYTES
STORE(t0, UNIT(0)(dst), .Ls_exc\@)
ADDC(t0, t1)
STORE(t1, UNIT(1)(dst), .Ls_exc\@)
ADDC(sum, t0)
STORE(t2, UNIT(2)(dst), .Ls_exc\@)
ADDC(t2, t3)
STORE(t3, UNIT(3)(dst), .Ls_exc\@)
ADDC(sum, t2)
STORE(t4, UNIT(4)(dst), .Ls_exc\@)
ADDC(t4, t5)
STORE(t5, UNIT(5)(dst), .Ls_exc\@)
ADDC(sum, t4)
STORE(t6, UNIT(6)(dst), .Ls_exc\@)
ADDC(t6, t7)
STORE(t7, UNIT(7)(dst), .Ls_exc\@)
ADDC(sum, t6)
.set reorder /* DADDI_WAR */
ADD dst, dst, 8*NBYTES
bgez len, 1b
.set noreorder
ADD len, 8*NBYTES # revert len (see above)
/*
* len == the number of bytes left to copy < 8*NBYTES
*/
.Lcleanup_both_aligned\@:
#define rem t7
beqz len, .Ldone\@
sltu t0, len, 4*NBYTES
bnez t0, .Lless_than_4units\@
and rem, len, (NBYTES-1) # rem = len % NBYTES
/*
* len >= 4*NBYTES
*/
LOAD(t0, UNIT(0)(src), .Ll_exc\@)
LOAD(t1, UNIT(1)(src), .Ll_exc_copy\@)
LOAD(t2, UNIT(2)(src), .Ll_exc_copy\@)
LOAD(t3, UNIT(3)(src), .Ll_exc_copy\@)
SUB len, len, 4*NBYTES
ADD src, src, 4*NBYTES
STORE(t0, UNIT(0)(dst), .Ls_exc\@)
ADDC(t0, t1)
STORE(t1, UNIT(1)(dst), .Ls_exc\@)
ADDC(sum, t0)
STORE(t2, UNIT(2)(dst), .Ls_exc\@)
ADDC(t2, t3)
STORE(t3, UNIT(3)(dst), .Ls_exc\@)
ADDC(sum, t2)
.set reorder /* DADDI_WAR */
ADD dst, dst, 4*NBYTES
beqz len, .Ldone\@
.set noreorder
.Lless_than_4units\@:
/*
* rem = len % NBYTES
*/
beq rem, len, .Lcopy_bytes\@
nop
1:
LOAD(t0, 0(src), .Ll_exc\@)
ADD src, src, NBYTES
SUB len, len, NBYTES
STORE(t0, 0(dst), .Ls_exc\@)
ADDC(sum, t0)
.set reorder /* DADDI_WAR */
ADD dst, dst, NBYTES
bne rem, len, 1b
.set noreorder
/*
* 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, .Ldone\@
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
LOAD(t0, 0(src), .Ll_exc\@)
SUB bits, bits, rem # bits = number of bits to discard
SHIFT_DISCARD t0, t0, bits
STREST(t0, -1(t1), .Ls_exc\@)
SHIFT_DISCARD_REVERT t0, t0, bits
.set reorder
ADDC(sum, t0)
b .Ldone\@
.set noreorder
.Ldst_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
LDFIRST(t3, FIRST(0)(src), .Ll_exc\@)
ADD t2, zero, NBYTES
LDREST(t3, REST(0)(src), .Ll_exc_copy\@)
SUB t2, t2, t1 # t2 = number of bytes copied
xor match, t0, t1
STFIRST(t3, FIRST(0)(dst), .Ls_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, .Ldone\@
SUB len, len, t2
ADD dst, dst, t2
beqz match, .Lboth_aligned\@
ADD src, src, t2
.Lsrc_unaligned_dst_aligned\@:
SRL t0, len, LOG_NBYTES+2 # +2 for 4 units/iter
beqz t0, .Lcleanup_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).
*/
LDFIRST(t0, FIRST(0)(src), .Ll_exc\@)
LDFIRST(t1, FIRST(1)(src), .Ll_exc_copy\@)
SUB len, len, 4*NBYTES
LDREST(t0, REST(0)(src), .Ll_exc_copy\@)
LDREST(t1, REST(1)(src), .Ll_exc_copy\@)
LDFIRST(t2, FIRST(2)(src), .Ll_exc_copy\@)
LDFIRST(t3, FIRST(3)(src), .Ll_exc_copy\@)
LDREST(t2, REST(2)(src), .Ll_exc_copy\@)
LDREST(t3, REST(3)(src), .Ll_exc_copy\@)
ADD src, src, 4*NBYTES
#ifdef CONFIG_CPU_SB1
nop # improves slotting
#endif
STORE(t0, UNIT(0)(dst), .Ls_exc\@)
ADDC(t0, t1)
STORE(t1, UNIT(1)(dst), .Ls_exc\@)
ADDC(sum, t0)
STORE(t2, UNIT(2)(dst), .Ls_exc\@)
ADDC(t2, t3)
STORE(t3, UNIT(3)(dst), .Ls_exc\@)
ADDC(sum, t2)
.set reorder /* DADDI_WAR */
ADD dst, dst, 4*NBYTES
bne len, rem, 1b
.set noreorder
.Lcleanup_src_unaligned\@:
beqz len, .Ldone\@
and rem, len, NBYTES-1 # rem = len % NBYTES
beq rem, len, .Lcopy_bytes\@
nop
1:
LDFIRST(t0, FIRST(0)(src), .Ll_exc\@)
LDREST(t0, REST(0)(src), .Ll_exc_copy\@)
ADD src, src, NBYTES
SUB len, len, NBYTES
STORE(t0, 0(dst), .Ls_exc\@)
ADDC(sum, t0)
.set reorder /* DADDI_WAR */
ADD dst, dst, NBYTES
bne len, rem, 1b
.set noreorder
.Lcopy_bytes_checklen\@:
beqz len, .Ldone\@
nop
.Lcopy_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 .Ll_exc_copy here to return correct sum on fault */
#define COPY_BYTE(N) \
LOADBU(t0, N(src), .Ll_exc_copy\@); \
SUB len, len, 1; \
STOREB(t0, N(dst), .Ls_exc\@); \
SLLV t0, t0, t3; \
addu t3, SHIFT_INC; \
beqz len, .Lcopy_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
LOADBU(t0, NBYTES-2(src), .Ll_exc_copy\@)
SUB len, len, 1
STOREB(t0, NBYTES-2(dst), .Ls_exc\@)
SLLV t0, t0, t3
or t2, t0
.Lcopy_bytes_done\@:
ADDC(sum, t2)
.Ldone\@:
/* fold checksum */
.set push
.set noat
#ifdef USE_DOUBLE
dsll32 v1, sum, 0
daddu sum, v1
sltu v1, sum, v1
dsra32 sum, sum, 0
addu sum, v1
#endif
#if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_LOONGSON3)
.set push
.set arch=mips32r2
wsbh v1, sum
movn sum, v1, odd
.set pop
#else
beqz odd, 1f /* odd buffer alignment? */
lui v1, 0x00ff
addu v1, 0x00ff
and t0, sum, v1
sll t0, t0, 8
srl sum, sum, 8
and sum, sum, v1
or sum, sum, t0
1:
#endif
.set pop
.set reorder
ADDC32(sum, psum)
jr ra
.set noreorder
.Ll_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)
*/
LOADK t0, TI_TASK($28)
li t2, SHIFT_START
LOADK t0, THREAD_BUADDR(t0)
1:
LOADBU(t1, 0(src), .Ll_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)
.set reorder /* DADDI_WAR */
ADD dst, dst, 1
bne src, t0, 1b
.set noreorder
.Ll_exc\@:
LOADK t0, TI_TASK($28)
nop
LOADK 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...
*/
.set reorder /* DADDI_WAR */
SUB src, len, 1
beqz len, .Ldone\@
.set noreorder
1: sb zero, 0(dst)
ADD dst, dst, 1
.set push
.set noat
#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
bnez src, 1b
SUB src, src, 1
#else
li v1, 1
bnez src, 1b
SUB src, src, v1
#endif
li v1, -EFAULT
b .Ldone\@
sw v1, (errptr)
.Ls_exc\@:
li v0, -1 /* invalid checksum */
li v1, -EFAULT
jr ra
sw v1, (errptr)
.set pop
.endm
LEAF(__csum_partial_copy_kernel)
#ifndef CONFIG_EVA
FEXPORT(__csum_partial_copy_to_user)
FEXPORT(__csum_partial_copy_from_user)
#endif
__BUILD_CSUM_PARTIAL_COPY_USER LEGACY_MODE USEROP USEROP 1
END(__csum_partial_copy_kernel)
#ifdef CONFIG_EVA
LEAF(__csum_partial_copy_to_user)
__BUILD_CSUM_PARTIAL_COPY_USER EVA_MODE KERNELOP USEROP 0
END(__csum_partial_copy_to_user)
LEAF(__csum_partial_copy_from_user)
__BUILD_CSUM_PARTIAL_COPY_USER EVA_MODE USEROP KERNELOP 0
END(__csum_partial_copy_from_user)
#endif
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