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Commit 192c4d90 authored by zhichang.yuan's avatar zhichang.yuan Committed by Catalin Marinas
Browse files

arm64: lib: Implement optimized string compare routines 



This patch, based on Linaro's Cortex Strings library, adds
an assembly optimized strcmp() and strncmp() functions.

Signed-off-by: default avatarZhichang Yuan <zhichang.yuan@linaro.org>
Signed-off-by: default avatarDeepak Saxena <dsaxena@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent d875c9b3

arch/arm64/include/asm/string.h

+6 −0
Original line number Diff line number Diff line
@@ -22,6 +22,12 @@ extern char *strrchr(const char *, int c); 
#define __HAVE_ARCH_STRCHR

extern char *strchr(const char *, int c);



#define __HAVE_ARCH_STRCMP

extern int strcmp(const char *, const char *);



#define __HAVE_ARCH_STRNCMP

extern int strncmp(const char *, const char *, __kernel_size_t);



#define __HAVE_ARCH_MEMCPY

extern void *memcpy(void *, const void *, __kernel_size_t);

arch/arm64/kernel/arm64ksyms.c

+2 −0
Original line number Diff line number Diff line
@@ -44,6 +44,8 @@ EXPORT_SYMBOL(memstart_addr); 
	/* string / mem functions */

EXPORT_SYMBOL(strchr);

EXPORT_SYMBOL(strrchr);

EXPORT_SYMBOL(strcmp);

EXPORT_SYMBOL(strncmp);

EXPORT_SYMBOL(memset);

EXPORT_SYMBOL(memcpy);

EXPORT_SYMBOL(memmove);

arch/arm64/lib/Makefile

+1 −1
Original line number Diff line number Diff line 
lib-y		:= bitops.o clear_user.o delay.o copy_from_user.o	\

		   copy_to_user.o copy_in_user.o copy_page.o		\

		   clear_page.o memchr.o memcpy.o memmove.o memset.o	\

		   memcmp.o strchr.o strrchr.o
 
		   memcmp.o strcmp.o strncmp.o strchr.o strrchr.o

arch/arm64/lib/strcmp.S

0 → 100644
+234 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2013 ARM Ltd.

 * Copyright (C) 2013 Linaro.

 *

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

 * and re-licensed under GPLv2 for the Linux kernel. The original code can

 * be found @

 *

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

 * files/head:/src/aarch64/

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/linkage.h>

#include <asm/assembler.h>



/*

 * compare two strings

 *

 * Parameters:

 *	x0 - const string 1 pointer

 *    x1 - const string 2 pointer

 * Returns:

 * x0 - an integer less than, equal to, or greater than zero

 * if  s1  is  found, respectively, to be less than, to match,

 * or be greater than s2.

 */



#define REP8_01 0x0101010101010101

#define REP8_7f 0x7f7f7f7f7f7f7f7f

#define REP8_80 0x8080808080808080



/* Parameters and result.  */

src1		.req	x0

src2		.req	x1

result		.req	x0



/* Internal variables.  */

data1		.req	x2

data1w		.req	w2

data2		.req	x3

data2w		.req	w3

has_nul		.req	x4

diff		.req	x5

syndrome	.req	x6

tmp1		.req	x7

tmp2		.req	x8

tmp3		.req	x9

zeroones	.req	x10

pos		.req	x11



ENTRY(strcmp)

	eor	tmp1, src1, src2

	mov	zeroones, #REP8_01

	tst	tmp1, #7

	b.ne	.Lmisaligned8

	ands	tmp1, src1, #7

	b.ne	.Lmutual_align



	/*

	* NUL detection works on the principle that (X - 1) & (~X) & 0x80

	* (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and

	* can be done in parallel across the entire word.

	*/

.Lloop_aligned:

	ldr	data1, [src1], #8

	ldr	data2, [src2], #8

.Lstart_realigned:

	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	eor	diff, data1, data2	/* Non-zero if differences found.  */

	bic	has_nul, tmp1, tmp2	/* Non-zero if NUL terminator.  */

	orr	syndrome, diff, has_nul

	cbz	syndrome, .Lloop_aligned

	b	.Lcal_cmpresult



.Lmutual_align:

	/*

	* Sources are mutually aligned, but are not currently at an

	* alignment boundary.  Round down the addresses and then mask off

	* the bytes that preceed the start point.

	*/

	bic	src1, src1, #7

	bic	src2, src2, #7

	lsl	tmp1, tmp1, #3		/* Bytes beyond alignment -> bits.  */

	ldr	data1, [src1], #8

	neg	tmp1, tmp1		/* Bits to alignment -64.  */

	ldr	data2, [src2], #8

	mov	tmp2, #~0

	/* Big-endian.  Early bytes are at MSB.  */

CPU_BE( lsl	tmp2, tmp2, tmp1 )	/* Shift (tmp1 & 63).  */

	/* Little-endian.  Early bytes are at LSB.  */

CPU_LE( lsr	tmp2, tmp2, tmp1 )	/* Shift (tmp1 & 63).  */



	orr	data1, data1, tmp2

	orr	data2, data2, tmp2

	b	.Lstart_realigned



.Lmisaligned8:

	/*

	* Get the align offset length to compare per byte first.

	* After this process, one string's address will be aligned.

	*/

	and	tmp1, src1, #7

	neg	tmp1, tmp1

	add	tmp1, tmp1, #8

	and	tmp2, src2, #7

	neg	tmp2, tmp2

	add	tmp2, tmp2, #8

	subs	tmp3, tmp1, tmp2

	csel	pos, tmp1, tmp2, hi /*Choose the maximum. */

.Ltinycmp:

	ldrb	data1w, [src1], #1

	ldrb	data2w, [src2], #1

	subs	pos, pos, #1

	ccmp	data1w, #1, #0, ne  /* NZCV = 0b0000.  */

	ccmp	data1w, data2w, #0, cs  /* NZCV = 0b0000.  */

	b.eq	.Ltinycmp

	cbnz	pos, 1f /*find the null or unequal...*/

	cmp	data1w, #1

	ccmp	data1w, data2w, #0, cs

	b.eq	.Lstart_align /*the last bytes are equal....*/

1:

	sub	result, data1, data2

	ret



.Lstart_align:

	ands	xzr, src1, #7

	b.eq	.Lrecal_offset

	/*process more leading bytes to make str1 aligned...*/

	add	src1, src1, tmp3

	add	src2, src2, tmp3

	/*load 8 bytes from aligned str1 and non-aligned str2..*/

	ldr	data1, [src1], #8

	ldr	data2, [src2], #8



	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	bic	has_nul, tmp1, tmp2

	eor	diff, data1, data2 /* Non-zero if differences found.  */

	orr	syndrome, diff, has_nul

	cbnz	syndrome, .Lcal_cmpresult

	/*How far is the current str2 from the alignment boundary...*/

	and	tmp3, tmp3, #7

.Lrecal_offset:

	neg	pos, tmp3

.Lloopcmp_proc:

	/*

	* Divide the eight bytes into two parts. First,backwards the src2

	* to an alignment boundary,load eight bytes from the SRC2 alignment

	* boundary,then compare with the relative bytes from SRC1.

	* If all 8 bytes are equal,then start the second part's comparison.

	* Otherwise finish the comparison.

	* This special handle can garantee all the accesses are in the

	* thread/task space in avoid to overrange access.

	*/

	ldr	data1, [src1,pos]

	ldr	data2, [src2,pos]

	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	bic	has_nul, tmp1, tmp2

	eor	diff, data1, data2  /* Non-zero if differences found.  */

	orr	syndrome, diff, has_nul

	cbnz	syndrome, .Lcal_cmpresult



	/*The second part process*/

	ldr	data1, [src1], #8

	ldr	data2, [src2], #8

	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	bic	has_nul, tmp1, tmp2

	eor	diff, data1, data2  /* Non-zero if differences found.  */

	orr	syndrome, diff, has_nul

	cbz	syndrome, .Lloopcmp_proc



.Lcal_cmpresult:

	/*

	* reversed the byte-order as big-endian,then CLZ can find the most

	* significant zero bits.

	*/

CPU_LE( rev	syndrome, syndrome )

CPU_LE( rev	data1, data1 )

CPU_LE( rev	data2, data2 )



	/*

	* For big-endian we cannot use the trick with the syndrome value

	* as carry-propagation can corrupt the upper bits if the trailing

	* bytes in the string contain 0x01.

	* However, if there is no NUL byte in the dword, we can generate

	* the result directly.  We ca not just subtract the bytes as the

	* MSB might be significant.

	*/

CPU_BE( cbnz	has_nul, 1f )

CPU_BE( cmp	data1, data2 )

CPU_BE( cset	result, ne )

CPU_BE( cneg	result, result, lo )

CPU_BE( ret )

CPU_BE( 1: )

	/*Re-compute the NUL-byte detection, using a byte-reversed value. */

CPU_BE(	rev	tmp3, data1 )

CPU_BE(	sub	tmp1, tmp3, zeroones )

CPU_BE(	orr	tmp2, tmp3, #REP8_7f )

CPU_BE(	bic	has_nul, tmp1, tmp2 )

CPU_BE(	rev	has_nul, has_nul )

CPU_BE(	orr	syndrome, diff, has_nul )



	clz	pos, syndrome

	/*

	* The MS-non-zero bit of the syndrome marks either the first bit

	* that is different, or the top bit of the first zero byte.

	* Shifting left now will bring the critical information into the

	* top bits.

	*/

	lsl	data1, data1, pos

	lsl	data2, data2, pos

	/*

	* But we need to zero-extend (char is unsigned) the value and then

	* perform a signed 32-bit subtraction.

	*/

	lsr	data1, data1, #56

	sub	result, data1, data2, lsr #56

	ret

ENDPROC(strcmp)

arch/arm64/lib/strncmp.S

0 → 100644
+310 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2013 ARM Ltd.

 * Copyright (C) 2013 Linaro.

 *

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

 * and re-licensed under GPLv2 for the Linux kernel. The original code can

 * be found @

 *

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

 * files/head:/src/aarch64/

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */



#include <linux/linkage.h>

#include <asm/assembler.h>



/*

 * compare two strings

 *

 * Parameters:

 *  x0 - const string 1 pointer

 *  x1 - const string 2 pointer

 *  x2 - the maximal length to be compared

 * Returns:

 *  x0 - an integer less than, equal to, or greater than zero if s1 is found,

 *     respectively, to be less than, to match, or be greater than s2.

 */



#define REP8_01 0x0101010101010101

#define REP8_7f 0x7f7f7f7f7f7f7f7f

#define REP8_80 0x8080808080808080



/* Parameters and result.  */

src1		.req	x0

src2		.req	x1

limit		.req	x2

result		.req	x0



/* Internal variables.  */

data1		.req	x3

data1w		.req	w3

data2		.req	x4

data2w		.req	w4

has_nul		.req	x5

diff		.req	x6

syndrome	.req	x7

tmp1		.req	x8

tmp2		.req	x9

tmp3		.req	x10

zeroones	.req	x11

pos		.req	x12

limit_wd	.req	x13

mask		.req	x14

endloop		.req	x15



ENTRY(strncmp)

	cbz	limit, .Lret0

	eor	tmp1, src1, src2

	mov	zeroones, #REP8_01

	tst	tmp1, #7

	b.ne	.Lmisaligned8

	ands	tmp1, src1, #7

	b.ne	.Lmutual_align

	/* Calculate the number of full and partial words -1.  */

	/*

	* when limit is mulitply of 8, if not sub 1,

	* the judgement of last dword will wrong.

	*/

	sub	limit_wd, limit, #1 /* limit != 0, so no underflow.  */

	lsr	limit_wd, limit_wd, #3  /* Convert to Dwords.  */



	/*

	* NUL detection works on the principle that (X - 1) & (~X) & 0x80

	* (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and

	* can be done in parallel across the entire word.

	*/

.Lloop_aligned:

	ldr	data1, [src1], #8

	ldr	data2, [src2], #8

.Lstart_realigned:

	subs	limit_wd, limit_wd, #1

	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	eor	diff, data1, data2  /* Non-zero if differences found.  */

	csinv	endloop, diff, xzr, pl  /* Last Dword or differences.*/

	bics	has_nul, tmp1, tmp2 /* Non-zero if NUL terminator.  */

	ccmp	endloop, #0, #0, eq

	b.eq	.Lloop_aligned



	/*Not reached the limit, must have found the end or a diff.  */

	tbz	limit_wd, #63, .Lnot_limit



	/* Limit % 8 == 0 => all bytes significant.  */

	ands	limit, limit, #7

	b.eq	.Lnot_limit



	lsl	limit, limit, #3    /* Bits -> bytes.  */

	mov	mask, #~0

CPU_BE( lsr	mask, mask, limit )

CPU_LE( lsl	mask, mask, limit )

	bic	data1, data1, mask

	bic	data2, data2, mask



	/* Make sure that the NUL byte is marked in the syndrome.  */

	orr	has_nul, has_nul, mask



.Lnot_limit:

	orr	syndrome, diff, has_nul

	b	.Lcal_cmpresult



.Lmutual_align:

	/*

	* Sources are mutually aligned, but are not currently at an

	* alignment boundary.  Round down the addresses and then mask off

	* the bytes that precede the start point.

	* We also need to adjust the limit calculations, but without

	* overflowing if the limit is near ULONG_MAX.

	*/

	bic	src1, src1, #7

	bic	src2, src2, #7

	ldr	data1, [src1], #8

	neg	tmp3, tmp1, lsl #3  /* 64 - bits(bytes beyond align). */

	ldr	data2, [src2], #8

	mov	tmp2, #~0

	sub	limit_wd, limit, #1 /* limit != 0, so no underflow.  */

	/* Big-endian.  Early bytes are at MSB.  */

CPU_BE( lsl	tmp2, tmp2, tmp3 )	/* Shift (tmp1 & 63).  */

	/* Little-endian.  Early bytes are at LSB.  */

CPU_LE( lsr	tmp2, tmp2, tmp3 )	/* Shift (tmp1 & 63).  */



	and	tmp3, limit_wd, #7

	lsr	limit_wd, limit_wd, #3

	/* Adjust the limit. Only low 3 bits used, so overflow irrelevant.*/

	add	limit, limit, tmp1

	add	tmp3, tmp3, tmp1

	orr	data1, data1, tmp2

	orr	data2, data2, tmp2

	add	limit_wd, limit_wd, tmp3, lsr #3

	b	.Lstart_realigned



/*when src1 offset is not equal to src2 offset...*/

.Lmisaligned8:

	cmp	limit, #8

	b.lo	.Ltiny8proc /*limit < 8... */

	/*

	* Get the align offset length to compare per byte first.

	* After this process, one string's address will be aligned.*/

	and	tmp1, src1, #7

	neg	tmp1, tmp1

	add	tmp1, tmp1, #8

	and	tmp2, src2, #7

	neg	tmp2, tmp2

	add	tmp2, tmp2, #8

	subs	tmp3, tmp1, tmp2

	csel	pos, tmp1, tmp2, hi /*Choose the maximum. */

	/*

	* Here, limit is not less than 8, so directly run .Ltinycmp

	* without checking the limit.*/

	sub	limit, limit, pos

.Ltinycmp:

	ldrb	data1w, [src1], #1

	ldrb	data2w, [src2], #1

	subs	pos, pos, #1

	ccmp	data1w, #1, #0, ne  /* NZCV = 0b0000.  */

	ccmp	data1w, data2w, #0, cs  /* NZCV = 0b0000.  */

	b.eq	.Ltinycmp

	cbnz	pos, 1f /*find the null or unequal...*/

	cmp	data1w, #1

	ccmp	data1w, data2w, #0, cs

	b.eq	.Lstart_align /*the last bytes are equal....*/

1:

	sub	result, data1, data2

	ret



.Lstart_align:

	lsr	limit_wd, limit, #3

	cbz	limit_wd, .Lremain8

	/*process more leading bytes to make str1 aligned...*/

	ands	xzr, src1, #7

	b.eq	.Lrecal_offset

	add	src1, src1, tmp3	/*tmp3 is positive in this branch.*/

	add	src2, src2, tmp3

	ldr	data1, [src1], #8

	ldr	data2, [src2], #8



	sub	limit, limit, tmp3

	lsr	limit_wd, limit, #3

	subs	limit_wd, limit_wd, #1



	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	eor	diff, data1, data2  /* Non-zero if differences found.  */

	csinv	endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/

	bics	has_nul, tmp1, tmp2

	ccmp	endloop, #0, #0, eq /*has_null is ZERO: no null byte*/

	b.ne	.Lunequal_proc

	/*How far is the current str2 from the alignment boundary...*/

	and	tmp3, tmp3, #7

.Lrecal_offset:

	neg	pos, tmp3

.Lloopcmp_proc:

	/*

	* Divide the eight bytes into two parts. First,backwards the src2

	* to an alignment boundary,load eight bytes from the SRC2 alignment

	* boundary,then compare with the relative bytes from SRC1.

	* If all 8 bytes are equal,then start the second part's comparison.

	* Otherwise finish the comparison.

	* This special handle can garantee all the accesses are in the

	* thread/task space in avoid to overrange access.

	*/

	ldr	data1, [src1,pos]

	ldr	data2, [src2,pos]

	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	bics	has_nul, tmp1, tmp2 /* Non-zero if NUL terminator.  */

	eor	diff, data1, data2  /* Non-zero if differences found.  */

	csinv	endloop, diff, xzr, eq

	cbnz	endloop, .Lunequal_proc



	/*The second part process*/

	ldr	data1, [src1], #8

	ldr	data2, [src2], #8

	subs	limit_wd, limit_wd, #1

	sub	tmp1, data1, zeroones

	orr	tmp2, data1, #REP8_7f

	eor	diff, data1, data2  /* Non-zero if differences found.  */

	csinv	endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/

	bics	has_nul, tmp1, tmp2

	ccmp	endloop, #0, #0, eq /*has_null is ZERO: no null byte*/

	b.eq	.Lloopcmp_proc



.Lunequal_proc:

	orr	syndrome, diff, has_nul

	cbz	syndrome, .Lremain8

.Lcal_cmpresult:

	/*

	* reversed the byte-order as big-endian,then CLZ can find the most

	* significant zero bits.

	*/

CPU_LE( rev	syndrome, syndrome )

CPU_LE( rev	data1, data1 )

CPU_LE( rev	data2, data2 )

	/*

	* For big-endian we cannot use the trick with the syndrome value

	* as carry-propagation can corrupt the upper bits if the trailing

	* bytes in the string contain 0x01.

	* However, if there is no NUL byte in the dword, we can generate

	* the result directly.  We can't just subtract the bytes as the

	* MSB might be significant.

	*/

CPU_BE( cbnz	has_nul, 1f )

CPU_BE( cmp	data1, data2 )

CPU_BE( cset	result, ne )

CPU_BE( cneg	result, result, lo )

CPU_BE( ret )

CPU_BE( 1: )

	/* Re-compute the NUL-byte detection, using a byte-reversed value.*/

CPU_BE( rev	tmp3, data1 )

CPU_BE( sub	tmp1, tmp3, zeroones )

CPU_BE( orr	tmp2, tmp3, #REP8_7f )

CPU_BE( bic	has_nul, tmp1, tmp2 )

CPU_BE( rev	has_nul, has_nul )

CPU_BE( orr	syndrome, diff, has_nul )

	/*

	* The MS-non-zero bit of the syndrome marks either the first bit

	* that is different, or the top bit of the first zero byte.

	* Shifting left now will bring the critical information into the

	* top bits.

	*/

	clz	pos, syndrome

	lsl	data1, data1, pos

	lsl	data2, data2, pos

	/*

	* But we need to zero-extend (char is unsigned) the value and then

	* perform a signed 32-bit subtraction.

	*/

	lsr	data1, data1, #56

	sub	result, data1, data2, lsr #56

	ret



.Lremain8:

	/* Limit % 8 == 0 => all bytes significant.  */

	ands	limit, limit, #7

	b.eq	.Lret0

.Ltiny8proc:

	ldrb	data1w, [src1], #1

	ldrb	data2w, [src2], #1

	subs	limit, limit, #1



	ccmp	data1w, #1, #0, ne  /* NZCV = 0b0000.  */

	ccmp	data1w, data2w, #0, cs  /* NZCV = 0b0000.  */

	b.eq	.Ltiny8proc

	sub	result, data1, data2

	ret



.Lret0:

	mov	result, #0

	ret

ENDPROC(strncmp)