Commit 28513304 authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

arm64: Import latest memcpy()/memmove() implementation 

Import the latest implementation of memcpy(), based on the
upstream code of string/aarch64/memcpy.S at commit afd6244 from
https://github.com/ARM-software/optimized-routines

, and subsuming
memmove() in the process.

Note that for simplicity Arm have chosen to contribute this code
to Linux under GPLv2 rather than the original MIT license.

Note also that the needs of the usercopy routines vs. regular memcpy()
have now diverged so far that we abandon the shared template idea
and the damage which that incurred to the tuning of LDP/STP loops.
We'll be back to tackle those routines separately in future.

Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/3c953af43506581b2422f61952261e76949ba711.1622128527.git.robin.murphy@arm.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent b6c4ea48

arch/arm64/lib/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

lib-y		:= clear_user.o delay.o copy_from_user.o		\

		   copy_to_user.o copy_in_user.o copy_page.o		\

		   clear_page.o csum.o memchr.o memcpy.o memmove.o	\

		   clear_page.o csum.o memchr.o memcpy.o		\

		   memset.o memcmp.o strcmp.o strncmp.o strlen.o	\

		   strnlen.o strchr.o strrchr.o tishift.o

arch/arm64/lib/memcpy.S

+229 −43
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (C) 2013 ARM Ltd.

 * Copyright (C) 2013 Linaro.

 * Copyright (c) 2012-2020, Arm Limited.

 *

 * This code is based on glibc cortex strings work originally authored by Linaro

 * be found @

 *

 * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/

 * files/head:/src/aarch64/

 * Adapted from the original at:

 * https://github.com/ARM-software/optimized-routines/blob/master/string/aarch64/memcpy.S

 */



#include <linux/linkage.h>

#include <asm/assembler.h>

#include <asm/cache.h>



/*

 * Copy a buffer from src to dest (alignment handled by the hardware)

/* Assumptions:

 *

 * ARMv8-a, AArch64, unaligned accesses.

 *

 * Parameters:

 *	x0 - dest

 *	x1 - src

 *	x2 - n

 * Returns:

 *	x0 - dest

 */

	.macro ldrb1 reg, ptr, val

	ldrb  \reg, [\ptr], \val

	.endm



	.macro strb1 reg, ptr, val

	strb \reg, [\ptr], \val

	.endm



	.macro ldrh1 reg, ptr, val

	ldrh  \reg, [\ptr], \val

	.endm

#define L(label) .L ## label



	.macro strh1 reg, ptr, val

	strh \reg, [\ptr], \val

	.endm

#define dstin	x0

#define src	x1

#define count	x2

#define dst	x3

#define srcend	x4

#define dstend	x5

#define A_l	x6

#define A_lw	w6

#define A_h	x7

#define B_l	x8

#define B_lw	w8

#define B_h	x9

#define C_l	x10

#define C_lw	w10

#define C_h	x11

#define D_l	x12

#define D_h	x13

#define E_l	x14

#define E_h	x15

#define F_l	x16

#define F_h	x17

#define G_l	count

#define G_h	dst

#define H_l	src

#define H_h	srcend

#define tmp1	x14



	.macro ldr1 reg, ptr, val

	ldr \reg, [\ptr], \val

	.endm

/* This implementation handles overlaps and supports both memcpy and memmove

   from a single entry point.  It uses unaligned accesses and branchless

   sequences to keep the code small, simple and improve performance.



	.macro str1 reg, ptr, val

	str \reg, [\ptr], \val

	.endm

   Copies are split into 3 main cases: small copies of up to 32 bytes, medium

   copies of up to 128 bytes, and large copies.  The overhead of the overlap

   check is negligible since it is only required for large copies.



	.macro ldp1 reg1, reg2, ptr, val

	ldp \reg1, \reg2, [\ptr], \val

	.endm



	.macro stp1 reg1, reg2, ptr, val

	stp \reg1, \reg2, [\ptr], \val

	.endm

   Large copies use a software pipelined loop processing 64 bytes per iteration.

   The destination pointer is 16-byte aligned to minimize unaligned accesses.

   The loop tail is handled by always copying 64 bytes from the end.

*/



SYM_FUNC_START_ALIAS(__memmove)

SYM_FUNC_START_WEAK_ALIAS_PI(memmove)

SYM_FUNC_START_ALIAS(__memcpy)

SYM_FUNC_START_WEAK_PI(memcpy)

#include "copy_template.S"

	add	srcend, src, count

	add	dstend, dstin, count

	cmp	count, 128

	b.hi	L(copy_long)

	cmp	count, 32

	b.hi	L(copy32_128)



	/* Small copies: 0..32 bytes.  */

	cmp	count, 16

	b.lo	L(copy16)

	ldp	A_l, A_h, [src]

	ldp	D_l, D_h, [srcend, -16]

	stp	A_l, A_h, [dstin]

	stp	D_l, D_h, [dstend, -16]

	ret



	/* Copy 8-15 bytes.  */

L(copy16):

	tbz	count, 3, L(copy8)

	ldr	A_l, [src]

	ldr	A_h, [srcend, -8]

	str	A_l, [dstin]

	str	A_h, [dstend, -8]

	ret



	.p2align 3

	/* Copy 4-7 bytes.  */

L(copy8):

	tbz	count, 2, L(copy4)

	ldr	A_lw, [src]

	ldr	B_lw, [srcend, -4]

	str	A_lw, [dstin]

	str	B_lw, [dstend, -4]

	ret



	/* Copy 0..3 bytes using a branchless sequence.  */

L(copy4):

	cbz	count, L(copy0)

	lsr	tmp1, count, 1

	ldrb	A_lw, [src]

	ldrb	C_lw, [srcend, -1]

	ldrb	B_lw, [src, tmp1]

	strb	A_lw, [dstin]

	strb	B_lw, [dstin, tmp1]

	strb	C_lw, [dstend, -1]

L(copy0):

	ret



	.p2align 4

	/* Medium copies: 33..128 bytes.  */

L(copy32_128):

	ldp	A_l, A_h, [src]

	ldp	B_l, B_h, [src, 16]

	ldp	C_l, C_h, [srcend, -32]

	ldp	D_l, D_h, [srcend, -16]

	cmp	count, 64

	b.hi	L(copy128)

	stp	A_l, A_h, [dstin]

	stp	B_l, B_h, [dstin, 16]

	stp	C_l, C_h, [dstend, -32]

	stp	D_l, D_h, [dstend, -16]

	ret



	.p2align 4

	/* Copy 65..128 bytes.  */

L(copy128):

	ldp	E_l, E_h, [src, 32]

	ldp	F_l, F_h, [src, 48]

	cmp	count, 96

	b.ls	L(copy96)

	ldp	G_l, G_h, [srcend, -64]

	ldp	H_l, H_h, [srcend, -48]

	stp	G_l, G_h, [dstend, -64]

	stp	H_l, H_h, [dstend, -48]

L(copy96):

	stp	A_l, A_h, [dstin]

	stp	B_l, B_h, [dstin, 16]

	stp	E_l, E_h, [dstin, 32]

	stp	F_l, F_h, [dstin, 48]

	stp	C_l, C_h, [dstend, -32]

	stp	D_l, D_h, [dstend, -16]

	ret



	.p2align 4

	/* Copy more than 128 bytes.  */

L(copy_long):

	/* Use backwards copy if there is an overlap.  */

	sub	tmp1, dstin, src

	cbz	tmp1, L(copy0)

	cmp	tmp1, count

	b.lo	L(copy_long_backwards)



	/* Copy 16 bytes and then align dst to 16-byte alignment.  */



	ldp	D_l, D_h, [src]

	and	tmp1, dstin, 15

	bic	dst, dstin, 15

	sub	src, src, tmp1

	add	count, count, tmp1	/* Count is now 16 too large.  */

	ldp	A_l, A_h, [src, 16]

	stp	D_l, D_h, [dstin]

	ldp	B_l, B_h, [src, 32]

	ldp	C_l, C_h, [src, 48]

	ldp	D_l, D_h, [src, 64]!

	subs	count, count, 128 + 16	/* Test and readjust count.  */

	b.ls	L(copy64_from_end)



L(loop64):

	stp	A_l, A_h, [dst, 16]

	ldp	A_l, A_h, [src, 16]

	stp	B_l, B_h, [dst, 32]

	ldp	B_l, B_h, [src, 32]

	stp	C_l, C_h, [dst, 48]

	ldp	C_l, C_h, [src, 48]

	stp	D_l, D_h, [dst, 64]!

	ldp	D_l, D_h, [src, 64]!

	subs	count, count, 64

	b.hi	L(loop64)



	/* Write the last iteration and copy 64 bytes from the end.  */

L(copy64_from_end):

	ldp	E_l, E_h, [srcend, -64]

	stp	A_l, A_h, [dst, 16]

	ldp	A_l, A_h, [srcend, -48]

	stp	B_l, B_h, [dst, 32]

	ldp	B_l, B_h, [srcend, -32]

	stp	C_l, C_h, [dst, 48]

	ldp	C_l, C_h, [srcend, -16]

	stp	D_l, D_h, [dst, 64]

	stp	E_l, E_h, [dstend, -64]

	stp	A_l, A_h, [dstend, -48]

	stp	B_l, B_h, [dstend, -32]

	stp	C_l, C_h, [dstend, -16]

	ret



	.p2align 4



	/* Large backwards copy for overlapping copies.

	   Copy 16 bytes and then align dst to 16-byte alignment.  */

L(copy_long_backwards):

	ldp	D_l, D_h, [srcend, -16]

	and	tmp1, dstend, 15

	sub	srcend, srcend, tmp1

	sub	count, count, tmp1

	ldp	A_l, A_h, [srcend, -16]

	stp	D_l, D_h, [dstend, -16]

	ldp	B_l, B_h, [srcend, -32]

	ldp	C_l, C_h, [srcend, -48]

	ldp	D_l, D_h, [srcend, -64]!

	sub	dstend, dstend, tmp1

	subs	count, count, 128

	b.ls	L(copy64_from_start)



L(loop64_backwards):

	stp	A_l, A_h, [dstend, -16]

	ldp	A_l, A_h, [srcend, -16]

	stp	B_l, B_h, [dstend, -32]

	ldp	B_l, B_h, [srcend, -32]

	stp	C_l, C_h, [dstend, -48]

	ldp	C_l, C_h, [srcend, -48]

	stp	D_l, D_h, [dstend, -64]!

	ldp	D_l, D_h, [srcend, -64]!

	subs	count, count, 64

	b.hi	L(loop64_backwards)



	/* Write the last iteration and copy 64 bytes from the start.  */

L(copy64_from_start):

	ldp	G_l, G_h, [src, 48]

	stp	A_l, A_h, [dstend, -16]

	ldp	A_l, A_h, [src, 32]

	stp	B_l, B_h, [dstend, -32]

	ldp	B_l, B_h, [src, 16]

	stp	C_l, C_h, [dstend, -48]

	ldp	C_l, C_h, [src]

	stp	D_l, D_h, [dstend, -64]

	stp	G_l, G_h, [dstin, 48]

	stp	A_l, A_h, [dstin, 32]

	stp	B_l, B_h, [dstin, 16]

	stp	C_l, C_h, [dstin]

	ret



SYM_FUNC_END_PI(memcpy)

EXPORT_SYMBOL(memcpy)

SYM_FUNC_END_ALIAS(__memcpy)

EXPORT_SYMBOL(__memcpy)

SYM_FUNC_END_ALIAS_PI(memmove)

EXPORT_SYMBOL(memmove)

SYM_FUNC_END_ALIAS(__memmove)

EXPORT_SYMBOL(__memmove)
 
 No newline at end of file

arch/arm64/lib/memmove.S

deleted100644 → 0
+0 −189
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/*

 * Copyright (C) 2013 ARM Ltd.

 * Copyright (C) 2013 Linaro.

 *

 * This code is based on glibc cortex strings work originally authored by Linaro

 * be found @

 *

 * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/

 * files/head:/src/aarch64/

 */



#include <linux/linkage.h>

#include <asm/assembler.h>

#include <asm/cache.h>



/*

 * Move a buffer from src to test (alignment handled by the hardware).

 * If dest <= src, call memcpy, otherwise copy in reverse order.

 *

 * Parameters:

 *	x0 - dest

 *	x1 - src

 *	x2 - n

 * Returns:

 *	x0 - dest

 */

dstin	.req	x0

src	.req	x1

count	.req	x2

tmp1	.req	x3

tmp1w	.req	w3

tmp2	.req	x4

tmp2w	.req	w4

tmp3	.req	x5

tmp3w	.req	w5

dst	.req	x6



A_l	.req	x7

A_h	.req	x8

B_l	.req	x9

B_h	.req	x10

C_l	.req	x11

C_h	.req	x12

D_l	.req	x13

D_h	.req	x14



SYM_FUNC_START_ALIAS(__memmove)

SYM_FUNC_START_WEAK_PI(memmove)

	cmp	dstin, src

	b.lo	__memcpy

	add	tmp1, src, count

	cmp	dstin, tmp1

	b.hs	__memcpy		/* No overlap.  */



	add	dst, dstin, count

	add	src, src, count

	cmp	count, #16

	b.lo	.Ltail15  /*probably non-alignment accesses.*/



	ands	tmp2, src, #15     /* Bytes to reach alignment.  */

	b.eq	.LSrcAligned

	sub	count, count, tmp2

	/*

	* process the aligned offset length to make the src aligned firstly.

	* those extra instructions' cost is acceptable. It also make the

	* coming accesses are based on aligned address.

	*/

	tbz	tmp2, #0, 1f

	ldrb	tmp1w, [src, #-1]!

	strb	tmp1w, [dst, #-1]!

1:

	tbz	tmp2, #1, 2f

	ldrh	tmp1w, [src, #-2]!

	strh	tmp1w, [dst, #-2]!

2:

	tbz	tmp2, #2, 3f

	ldr	tmp1w, [src, #-4]!

	str	tmp1w, [dst, #-4]!

3:

	tbz	tmp2, #3, .LSrcAligned

	ldr	tmp1, [src, #-8]!

	str	tmp1, [dst, #-8]!



.LSrcAligned:

	cmp	count, #64

	b.ge	.Lcpy_over64



	/*

	* Deal with small copies quickly by dropping straight into the

	* exit block.

	*/

.Ltail63:

	/*

	* Copy up to 48 bytes of data. At this point we only need the

	* bottom 6 bits of count to be accurate.

	*/

	ands	tmp1, count, #0x30

	b.eq	.Ltail15

	cmp	tmp1w, #0x20

	b.eq	1f

	b.lt	2f

	ldp	A_l, A_h, [src, #-16]!

	stp	A_l, A_h, [dst, #-16]!

1:

	ldp	A_l, A_h, [src, #-16]!

	stp	A_l, A_h, [dst, #-16]!

2:

	ldp	A_l, A_h, [src, #-16]!

	stp	A_l, A_h, [dst, #-16]!



.Ltail15:

	tbz	count, #3, 1f

	ldr	tmp1, [src, #-8]!

	str	tmp1, [dst, #-8]!

1:

	tbz	count, #2, 2f

	ldr	tmp1w, [src, #-4]!

	str	tmp1w, [dst, #-4]!

2:

	tbz	count, #1, 3f

	ldrh	tmp1w, [src, #-2]!

	strh	tmp1w, [dst, #-2]!

3:

	tbz	count, #0, .Lexitfunc

	ldrb	tmp1w, [src, #-1]

	strb	tmp1w, [dst, #-1]



.Lexitfunc:

	ret



.Lcpy_over64:

	subs	count, count, #128

	b.ge	.Lcpy_body_large

	/*

	* Less than 128 bytes to copy, so handle 64 bytes here and then jump

	* to the tail.

	*/

	ldp	A_l, A_h, [src, #-16]

	stp	A_l, A_h, [dst, #-16]

	ldp	B_l, B_h, [src, #-32]

	ldp	C_l, C_h, [src, #-48]

	stp	B_l, B_h, [dst, #-32]

	stp	C_l, C_h, [dst, #-48]

	ldp	D_l, D_h, [src, #-64]!

	stp	D_l, D_h, [dst, #-64]!



	tst	count, #0x3f

	b.ne	.Ltail63

	ret



	/*

	* Critical loop. Start at a new cache line boundary. Assuming

	* 64 bytes per line this ensures the entire loop is in one line.

	*/

	.p2align	L1_CACHE_SHIFT

.Lcpy_body_large:

	/* pre-load 64 bytes data. */

	ldp	A_l, A_h, [src, #-16]

	ldp	B_l, B_h, [src, #-32]

	ldp	C_l, C_h, [src, #-48]

	ldp	D_l, D_h, [src, #-64]!

1:

	/*

	* interlace the load of next 64 bytes data block with store of the last

	* loaded 64 bytes data.

	*/

	stp	A_l, A_h, [dst, #-16]

	ldp	A_l, A_h, [src, #-16]

	stp	B_l, B_h, [dst, #-32]

	ldp	B_l, B_h, [src, #-32]

	stp	C_l, C_h, [dst, #-48]

	ldp	C_l, C_h, [src, #-48]

	stp	D_l, D_h, [dst, #-64]!

	ldp	D_l, D_h, [src, #-64]!

	subs	count, count, #64

	b.ge	1b

	stp	A_l, A_h, [dst, #-16]

	stp	B_l, B_h, [dst, #-32]

	stp	C_l, C_h, [dst, #-48]

	stp	D_l, D_h, [dst, #-64]!



	tst	count, #0x3f

	b.ne	.Ltail63

	ret

SYM_FUNC_END_PI(memmove)

EXPORT_SYMBOL(memmove)

SYM_FUNC_END_ALIAS(__memmove)

EXPORT_SYMBOL(__memmove)