arm64: String function updates

index c0671e793ea9..498f0d9941d9 100644
@@ -1,247 +1,139 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (C) 2013 ARM Ltd.
- * Copyright (C) 2013 Linaro.
+ * Copyright (c) 2013-2020, 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/memcmp.S
  */
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
-/*
-* compare memory areas(when two memory areas' offset are different,
-* alignment handled by the hardware)
-*
-* Parameters:
-*  x0 - const memory area 1 pointer
-*  x1 - const memory area 2 pointer
-*  x2 - the maximal compare byte length
-* Returns:
-*  x0 - a compare result, maybe less than, equal to, or greater than ZERO
-*/
+/* Assumptions:
+ *
+ * ARMv8-a, AArch64, unaligned accesses.
+ */
+
+#define L(label) .L ## label
 
 /* Parameters and result.  */
-src1		.req	x0
-src2		.req	x1
-limit		.req	x2
-result		.req	x0
+#define src1		x0
+#define src2		x1
+#define limit		x2
+#define result		w0
 
 /* Internal variables.  */
-data1		.req	x3
-data1w		.req	w3
-data2		.req	x4
-data2w		.req	w4
-has_nul		.req	x5
-diff		.req	x6
-endloop		.req	x7
-tmp1		.req	x8
-tmp2		.req	x9
-tmp3		.req	x10
-pos		.req	x11
-limit_wd	.req	x12
-mask		.req	x13
+#define data1		x3
+#define data1w		w3
+#define data1h		x4
+#define data2		x5
+#define data2w		w5
+#define data2h		x6
+#define tmp1		x7
+#define tmp2		x8
 
 SYM_FUNC_START_WEAK_PI(memcmp)
-	cbz	limit, .Lret0
-	eor	tmp1, src1, src2
-	tst	tmp1, #7
-	b.ne	.Lmisaligned8
-	ands	tmp1, src1, #7
-	b.ne	.Lmutual_align
-	sub	limit_wd, limit, #1 /* limit != 0, so no underflow.  */
-	lsr	limit_wd, limit_wd, #3 /* Convert to Dwords.  */
-	/*
-	* The input source addresses are at alignment boundary.
-	* Directly compare eight bytes each time.
-	*/
-.Lloop_aligned:
-	ldr	data1, [src1], #8
-	ldr	data2, [src2], #8
-.Lstart_realigned:
-	subs	limit_wd, limit_wd, #1
-	eor	diff, data1, data2	/* Non-zero if differences found.  */
-	csinv	endloop, diff, xzr, cs	/* Last Dword or differences.  */
-	cbz	endloop, .Lloop_aligned
+	subs	limit, limit, 8
+	b.lo	L(less8)
 
-	/* Not reached the limit, must have found a diff.  */
-	tbz	limit_wd, #63, .Lnot_limit
+	ldr	data1, [src1], 8
+	ldr	data2, [src2], 8
+	cmp	data1, data2
+	b.ne	L(return)
 
-	/* Limit % 8 == 0 => the diff is in the last 8 bytes. */
-	ands	limit, limit, #7
-	b.eq	.Lnot_limit
-	/*
-	* The remained bytes less than 8. It is needed to extract valid data
-	* from last eight bytes of the intended memory range.
-	*/
-	lsl	limit, limit, #3	/* bytes-> bits.  */
-	mov	mask, #~0
-CPU_BE( lsr	mask, mask, limit )
-CPU_LE( lsl	mask, mask, limit )
-	bic	data1, data1, mask
-	bic	data2, data2, mask
+	subs	limit, limit, 8
+	b.gt	L(more16)
 
-	orr	diff, diff, mask
-	b	.Lnot_limit
+	ldr	data1, [src1, limit]
+	ldr	data2, [src2, limit]
+	b	L(return)
 
-.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.
-	*/
-	bic	src1, src1, #7
-	bic	src2, src2, #7
-	ldr	data1, [src1], #8
-	ldr	data2, [src2], #8
-	/*
-	* We can not add limit with alignment offset(tmp1) here. Since the
-	* addition probably make the limit overflown.
-	*/
-	sub	limit_wd, limit, #1/*limit != 0, so no underflow.*/
-	and	tmp3, limit_wd, #7
-	lsr	limit_wd, limit_wd, #3
-	add	tmp3, tmp3, tmp1
-	add	limit_wd, limit_wd, tmp3, lsr #3
-	add	limit, limit, tmp1/* Adjust the limit for the extra.  */
+L(more16):
+	ldr	data1, [src1], 8
+	ldr	data2, [src2], 8
+	cmp	data1, data2
+	bne	L(return)
 
-	lsl	tmp1, tmp1, #3/* Bytes beyond alignment -> bits.*/
-	neg	tmp1, tmp1/* Bits to alignment -64.  */
-	mov	tmp2, #~0
-	/*mask off the non-intended bytes before the start address.*/
-CPU_BE( lsl	tmp2, tmp2, tmp1 )/*Big-endian.Early bytes are at MSB*/
-	/* Little-endian.  Early bytes are at LSB.  */
-CPU_LE( lsr	tmp2, tmp2, tmp1 )
+	/* Jump directly to comparing the last 16 bytes for 32 byte (or less)
+	   strings.  */
+	subs	limit, limit, 16
+	b.ls	L(last_bytes)
 
-	orr	data1, data1, tmp2
-	orr	data2, data2, tmp2
-	b	.Lstart_realigned
+	/* We overlap loads between 0-32 bytes at either side of SRC1 when we
+	   try to align, so limit it only to strings larger than 128 bytes.  */
+	cmp	limit, 96
+	b.ls	L(loop16)
 
-	/*src1 and src2 have different alignment offset.*/
-.Lmisaligned8:
-	cmp	limit, #8
-	b.lo	.Ltiny8proc /*limit < 8: compare byte by byte*/
+	/* Align src1 and adjust src2 with bytes not yet done.  */
+	and	tmp1, src1, 15
+	add	limit, limit, tmp1
+	sub	src1, src1, tmp1
+	sub	src2, src2, tmp1
 
-	and	tmp1, src1, #7
-	neg	tmp1, tmp1
-	add	tmp1, tmp1, #8/*valid length in the first 8 bytes of src1*/
-	and	tmp2, src2, #7
-	neg	tmp2, tmp2
-	add	tmp2, tmp2, #8/*valid length in the first 8 bytes of src2*/
-	subs	tmp3, tmp1, tmp2
-	csel	pos, tmp1, tmp2, hi /*Choose the maximum.*/
+	/* Loop performing 16 bytes per iteration using aligned src1.
+	   Limit is pre-decremented by 16 and must be larger than zero.
+	   Exit if <= 16 bytes left to do or if the data is not equal.  */
+	.p2align 4
+L(loop16):
+	ldp	data1, data1h, [src1], 16
+	ldp	data2, data2h, [src2], 16
+	subs	limit, limit, 16
+	ccmp	data1, data2, 0, hi
+	ccmp	data1h, data2h, 0, eq
+	b.eq	L(loop16)
 
-	sub	limit, limit, pos
-	/*compare the proceeding bytes in the first 8 byte segment.*/
-.Ltinycmp:
-	ldrb	data1w, [src1], #1
-	ldrb	data2w, [src2], #1
-	subs	pos, pos, #1
-	ccmp	data1w, data2w, #0, ne  /* NZCV = 0b0000.  */
-	b.eq	.Ltinycmp
-	cbnz	pos, 1f /*diff occurred before the last byte.*/
+	cmp	data1, data2
+	bne	L(return)
+	mov	data1, data1h
+	mov	data2, data2h
+	cmp	data1, data2
+	bne	L(return)
+
+	/* Compare last 1-16 bytes using unaligned access.  */
+L(last_bytes):
+	add	src1, src1, limit
+	add	src2, src2, limit
+	ldp	data1, data1h, [src1]
+	ldp	data2, data2h, [src2]
+	cmp	data1, data2
+	bne	L(return)
+	mov	data1, data1h
+	mov	data2, data2h
+	cmp	data1, data2
+
+	/* Compare data bytes and set return value to 0, -1 or 1.  */
+L(return):
+#ifndef __AARCH64EB__
+	rev	data1, data1
+	rev	data2, data2
+#endif
+	cmp	data1, data2
+L(ret_eq):
+	cset	result, ne
+	cneg	result, result, lo
+	ret
+
+	.p2align 4
+	/* Compare up to 8 bytes.  Limit is [-8..-1].  */
+L(less8):
+	adds	limit, limit, 4
+	b.lo	L(less4)
+	ldr	data1w, [src1], 4
+	ldr	data2w, [src2], 4
 	cmp	data1w, data2w
-	b.eq	.Lstart_align
-1:
-	sub	result, data1, data2
+	b.ne	L(return)
+	sub	limit, limit, 4
+L(less4):
+	adds	limit, limit, 4
+	beq	L(ret_eq)
+L(byte_loop):
+	ldrb	data1w, [src1], 1
+	ldrb	data2w, [src2], 1
+	subs	limit, limit, 1
+	ccmp	data1w, data2w, 0, ne	/* NZCV = 0b0000.  */
+	b.eq	L(byte_loop)
+	sub	result, data1w, data2w
 	ret
 
-.Lstart_align:
-	lsr	limit_wd, limit, #3
-	cbz	limit_wd, .Lremain8
-
-	ands	xzr, src1, #7
-	b.eq	.Lrecal_offset
-	/*process more leading bytes to make src1 aligned...*/
-	add	src1, src1, tmp3 /*backwards src1 to alignment boundary*/
-	add	src2, src2, tmp3
-	sub	limit, limit, tmp3
-	lsr	limit_wd, limit, #3
-	cbz	limit_wd, .Lremain8
-	/*load 8 bytes from aligned SRC1..*/
-	ldr	data1, [src1], #8
-	ldr	data2, [src2], #8
-
-	subs	limit_wd, limit_wd, #1
-	eor	diff, data1, data2  /*Non-zero if differences found.*/
-	csinv	endloop, diff, xzr, ne
-	cbnz	endloop, .Lunequal_proc
-	/*How far is the current SRC2 from the alignment boundary...*/
-	and	tmp3, tmp3, #7
-
-.Lrecal_offset:/*src1 is aligned now..*/
-	neg	pos, tmp3
-.Lloopcmp_proc:
-	/*
-	* Divide the eight bytes into two parts. First,backwards the src2
-	* to an alignment boundary,load eight bytes and compare from
-	* the SRC2 alignment boundary. 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]
-	eor	diff, data1, data2  /* Non-zero if differences found.  */
-	cbnz	diff, .Lnot_limit
-
-	/*The second part process*/
-	ldr	data1, [src1], #8
-	ldr	data2, [src2], #8
-	eor	diff, data1, data2  /* Non-zero if differences found.  */
-	subs	limit_wd, limit_wd, #1
-	csinv	endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/
-	cbz	endloop, .Lloopcmp_proc
-.Lunequal_proc:
-	cbz	diff, .Lremain8
-
-/* There is difference occurred in the latest comparison. */
-.Lnot_limit:
-/*
-* For little endian,reverse the low significant equal bits into MSB,then
-* following CLZ can find how many equal bits exist.
-*/
-CPU_LE( rev	diff, diff )
-CPU_LE( rev	data1, data1 )
-CPU_LE( rev	data2, data2 )
-
-	/*
-	* The MS-non-zero bit of DIFF marks either the first bit
-	* that is different, or the end of the significant data.
-	* Shifting left now will bring the critical information into the
-	* top bits.
-	*/
-	clz	pos, diff
-	lsl	data1, data1, pos
-	lsl	data2, data2, pos
-	/*
-	* We need to zero-extend (char is unsigned) the value and then
-	* perform a signed subtraction.
-	*/
-	lsr	data1, data1, #56
-	sub	result, data1, data2, lsr #56
-	ret
-
-.Lremain8:
-	/* Limit % 8 == 0 =>. all data are equal.*/
-	ands	limit, limit, #7
-	b.eq	.Lret0
-
-.Ltiny8proc:
-	ldrb	data1w, [src1], #1
-	ldrb	data2w, [src2], #1
-	subs	limit, limit, #1
-
-	ccmp	data1w, data2w, #0, ne  /* NZCV = 0b0000. */
-	b.eq	.Ltiny8proc
-	sub	result, data1, data2
-	ret
-.Lret0:
-	mov	result, #0
-	ret
 SYM_FUNC_END_PI(memcmp)
 EXPORT_SYMBOL_NOKASAN(memcmp)

index 4e79566726c8..e82ccb6c2f93 100644
@@ -1,84 +1,123 @@
 /* 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/strcmp.S
  */
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
-/*
- * compare two strings
+/* Assumptions:
  *
- * 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.
+ * ARMv8-a, AArch64
  */
 
+#define L(label) .L ## label
+
 #define REP8_01 0x0101010101010101
 #define REP8_7f 0x7f7f7f7f7f7f7f7f
 #define REP8_80 0x8080808080808080
 
 /* Parameters and result.  */
-src1		.req	x0
-src2		.req	x1
-result		.req	x0
+#define src1		x0
+#define src2		x1
+#define result		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
+#define data1		x2
+#define data1w		w2
+#define data2		x3
+#define data2w		w3
+#define has_nul		x4
+#define diff		x5
+#define syndrome	x6
+#define tmp1		x7
+#define tmp2		x8
+#define tmp3		x9
+#define zeroones	x10
+#define pos		x11
 
+	/* Start of performance-critical section  -- one 64B cache line.  */
+	.align 6
 SYM_FUNC_START_WEAK_PI(strcmp)
 	eor	tmp1, src1, src2
 	mov	zeroones, #REP8_01
 	tst	tmp1, #7
-	b.ne	.Lmisaligned8
+	b.ne	L(misaligned8)
 	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:
+	b.ne	L(mutual_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.  */
+L(loop_aligned):
 	ldr	data1, [src1], #8
 	ldr	data2, [src2], #8
-.Lstart_realigned:
+L(start_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
+	cbz	syndrome, L(loop_aligned)
+	/* End of performance-critical section  -- one 64B cache line.  */
 
-.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.
-	*/
+L(end):
+#ifndef	__AARCH64EB__
+	rev	syndrome, syndrome
+	rev	data1, data1
+	/* 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
+	rev	data2, data2
+	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
+#else
+	/* 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.  */
+	cbnz	has_nul, 1f
+	cmp	data1, data2
+	cset	result, ne
+	cneg	result, result, lo
+	ret
+1:
+	/* Re-compute the NUL-byte detection, using a byte-reversed value.  */
+	rev	tmp3, data1
+	sub	tmp1, tmp3, zeroones
+	orr	tmp2, tmp3, #REP8_7f
+	bic	has_nul, tmp1, tmp2
+	rev	has_nul, has_nul
+	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
+#endif
+
+L(mutual_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.  */

@@ -86,138 +125,52 @@ SYM_FUNC_START_WEAK_PI(strcmp)
 	neg	tmp1, tmp1		/* Bits to alignment -64.  */
 	ldr	data2, [src2], #8
 	mov	tmp2, #~0
+#ifdef __AARCH64EB__
 	/* Big-endian.  Early bytes are at MSB.  */
-CPU_BE( lsl	tmp2, tmp2, tmp1 )	/* Shift (tmp1 & 63).  */
+	lsl	tmp2, tmp2, tmp1	/* Shift (tmp1 & 63).  */
+#else
 	/* Little-endian.  Early bytes are at LSB.  */
-CPU_LE( lsr	tmp2, tmp2, tmp1 )	/* Shift (tmp1 & 63).  */
-
+	lsr	tmp2, tmp2, tmp1	/* Shift (tmp1 & 63).  */
+#endif
 	orr	data1, data1, tmp2
 	orr	data2, data2, tmp2
-	b	.Lstart_realigned
+	b	L(start_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:
+L(misaligned8):
+	/* Align SRC1 to 8 bytes and then compare 8 bytes at a time, always
+	   checking to make sure that we don't access beyond page boundary in
+	   SRC2.  */
+	tst	src1, #7
+	b.eq	L(loop_misaligned)
+L(do_misaligned):
 	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:
+	ccmp	data1w, data2w, #0, cs	/* NZCV = 0b0000.  */
+	b.ne	L(done)
+	tst	src1, #7
+	b.ne	L(do_misaligned)
+
+L(loop_misaligned):
+	/* Test if we are within the last dword of the end of a 4K page.  If
+	   yes then jump back to the misaligned loop to copy a byte at a time.  */
+	and	tmp1, src2, #0xff8
+	eor	tmp1, tmp1, #0xff8
+	cbz	tmp1, L(do_misaligned)
+	ldr	data1, [src1], #8
+	ldr	data2, [src2], #8
+
+	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, L(loop_misaligned)
+	b	L(end)
+
+L(done):
 	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 cannot 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
 SYM_FUNC_END_PI(strcmp)
 EXPORT_SYMBOL_NOKASAN(strcmp)

index ee3ed882dd79..b557185b54a5 100644
@@ -1,115 +1,203 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (C) 2013 ARM Ltd.
- * Copyright (C) 2013 Linaro.
+ * Copyright (c) 2013, 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/strlen.S
  */
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
-/*
- * calculate the length of a string
+/* Assumptions:
  *
- * Parameters:
- *	x0 - const string pointer
- * Returns:
- *	x0 - the return length of specific string
+ * ARMv8-a, AArch64, unaligned accesses, min page size 4k.
  */
 
+#define L(label) .L ## label
+
 /* Arguments and results.  */
-srcin		.req	x0
-len		.req	x0
+#define srcin		x0
+#define len		x0
 
 /* Locals and temporaries.  */
-src		.req	x1
-data1		.req	x2
-data2		.req	x3
-data2a		.req	x4
-has_nul1	.req	x5
-has_nul2	.req	x6
-tmp1		.req	x7
-tmp2		.req	x8
-tmp3		.req	x9
-tmp4		.req	x10
-zeroones	.req	x11
-pos		.req	x12
+#define src		x1
+#define data1		x2
+#define data2		x3
+#define has_nul1	x4
+#define has_nul2	x5
+#define tmp1		x4
+#define tmp2		x5
+#define tmp3		x6
+#define tmp4		x7
+#define zeroones	x8
+
+	/* 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. A faster check
+	   (X - 1) & 0x80 is zero for non-NUL ASCII characters, but gives
+	   false hits for characters 129..255.	*/
 
 #define REP8_01 0x0101010101010101
 #define REP8_7f 0x7f7f7f7f7f7f7f7f
 #define REP8_80 0x8080808080808080
 
+#define MIN_PAGE_SIZE 4096
+
+	/* Since strings are short on average, we check the first 16 bytes
+	   of the string for a NUL character.  In order to do an unaligned ldp
+	   safely we have to do a page cross check first.  If there is a NUL
+	   byte we calculate the length from the 2 8-byte words using
+	   conditional select to reduce branch mispredictions (it is unlikely
+	   strlen will be repeatedly called on strings with the same length).
+
+	   If the string is longer than 16 bytes, we align src so don't need
+	   further page cross checks, and process 32 bytes per iteration
+	   using the fast NUL check.  If we encounter non-ASCII characters,
+	   fallback to a second loop using the full NUL check.
+
+	   If the page cross check fails, we read 16 bytes from an aligned
+	   address, remove any characters before the string, and continue
+	   in the main loop using aligned loads.  Since strings crossing a
+	   page in the first 16 bytes are rare (probability of
+	   16/MIN_PAGE_SIZE ~= 0.4%), this case does not need to be optimized.
+
+	   AArch64 systems have a minimum page size of 4k.  We don't bother
+	   checking for larger page sizes - the cost of setting up the correct
+	   page size is just not worth the extra gain from a small reduction in
+	   the cases taking the slow path.  Note that we only care about
+	   whether the first fetch, which may be misaligned, crosses a page
+	   boundary.  */
+
 SYM_FUNC_START_WEAK_PI(strlen)
-	mov	zeroones, #REP8_01
-	bic	src, srcin, #15
-	ands	tmp1, srcin, #15
-	b.ne	.Lmisaligned
-	/*
-	* 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.
-	*/
-	/*
-	* The inner loop deals with two Dwords at a time. This has a
-	* slightly higher start-up cost, but we should win quite quickly,
-	* especially on cores with a high number of issue slots per
-	* cycle, as we get much better parallelism out of the operations.
-	*/
-.Lloop:
-	ldp	data1, data2, [src], #16
-.Lrealigned:
+	and	tmp1, srcin, MIN_PAGE_SIZE - 1
+	mov	zeroones, REP8_01
+	cmp	tmp1, MIN_PAGE_SIZE - 16
+	b.gt	L(page_cross)
+	ldp	data1, data2, [srcin]
+#ifdef __AARCH64EB__
+	/* For big-endian, carry propagation (if the final byte in the
+	   string is 0x01) means we cannot use has_nul1/2 directly.
+	   Since we expect strings to be small and early-exit,
+	   byte-swap the data now so has_null1/2 will be correct.  */
+	rev	data1, data1
+	rev	data2, data2
+#endif
 	sub	tmp1, data1, zeroones
-	orr	tmp2, data1, #REP8_7f
+	orr	tmp2, data1, REP8_7f
 	sub	tmp3, data2, zeroones
-	orr	tmp4, data2, #REP8_7f
-	bic	has_nul1, tmp1, tmp2
-	bics	has_nul2, tmp3, tmp4
-	ccmp	has_nul1, #0, #0, eq	/* NZCV = 0000  */
-	b.eq	.Lloop
+	orr	tmp4, data2, REP8_7f
+	bics	has_nul1, tmp1, tmp2
+	bic	has_nul2, tmp3, tmp4
+	ccmp	has_nul2, 0, 0, eq
+	beq	L(main_loop_entry)
 
-	sub	len, src, srcin
-	cbz	has_nul1, .Lnul_in_data2
-CPU_BE(	mov	data2, data1 )	/*prepare data to re-calculate the syndrome*/
-	sub	len, len, #8
-	mov	has_nul2, has_nul1
-.Lnul_in_data2:
-	/*
-	* For big-endian, carry propagation (if the final byte in the
-	* string is 0x01) means we cannot use has_nul directly.  The
-	* easiest way to get the correct byte is to byte-swap the data
-	* and calculate the syndrome a second time.
-	*/
-CPU_BE( rev	data2, data2 )
-CPU_BE( sub	tmp1, data2, zeroones )
-CPU_BE( orr	tmp2, data2, #REP8_7f )
-CPU_BE( bic	has_nul2, tmp1, tmp2 )
-
-	sub	len, len, #8
-	rev	has_nul2, has_nul2
-	clz	pos, has_nul2
-	add	len, len, pos, lsr #3		/* Bits to bytes.  */
+	/* Enter with C = has_nul1 == 0.  */
+	csel	has_nul1, has_nul1, has_nul2, cc
+	mov	len, 8
+	rev	has_nul1, has_nul1
+	clz	tmp1, has_nul1
+	csel	len, xzr, len, cc
+	add	len, len, tmp1, lsr 3
 	ret
 
-.Lmisaligned:
-	cmp	tmp1, #8
-	neg	tmp1, tmp1
-	ldp	data1, data2, [src], #16
-	lsl	tmp1, tmp1, #3		/* Bytes beyond alignment -> bits.  */
-	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).  */
+	/* The inner loop processes 32 bytes per iteration and uses the fast
+	   NUL check.  If we encounter non-ASCII characters, use a second
+	   loop with the accurate NUL check.  */
+	.p2align 4
+L(main_loop_entry):
+	bic	src, srcin, 15
+	sub	src, src, 16
+L(main_loop):
+	ldp	data1, data2, [src, 32]!
+L(page_cross_entry):
+	sub	tmp1, data1, zeroones
+	sub	tmp3, data2, zeroones
+	orr	tmp2, tmp1, tmp3
+	tst	tmp2, zeroones, lsl 7
+	bne	1f
+	ldp	data1, data2, [src, 16]
+	sub	tmp1, data1, zeroones
+	sub	tmp3, data2, zeroones
+	orr	tmp2, tmp1, tmp3
+	tst	tmp2, zeroones, lsl 7
+	beq	L(main_loop)
+	add	src, src, 16
+1:
+	/* The fast check failed, so do the slower, accurate NUL check.	 */
+	orr	tmp2, data1, REP8_7f
+	orr	tmp4, data2, REP8_7f
+	bics	has_nul1, tmp1, tmp2
+	bic	has_nul2, tmp3, tmp4
+	ccmp	has_nul2, 0, 0, eq
+	beq	L(nonascii_loop)
+
+	/* Enter with C = has_nul1 == 0.  */
+L(tail):
+#ifdef __AARCH64EB__
+	/* For big-endian, carry propagation (if the final byte in the
+	   string is 0x01) means we cannot use has_nul1/2 directly.  The
+	   easiest way to get the correct byte is to byte-swap the data
+	   and calculate the syndrome a second time.  */
+	csel	data1, data1, data2, cc
+	rev	data1, data1
+	sub	tmp1, data1, zeroones
+	orr	tmp2, data1, REP8_7f
+	bic	has_nul1, tmp1, tmp2
+#else
+	csel	has_nul1, has_nul1, has_nul2, cc
+#endif
+	sub	len, src, srcin
+	rev	has_nul1, has_nul1
+	add	tmp2, len, 8
+	clz	tmp1, has_nul1
+	csel	len, len, tmp2, cc
+	add	len, len, tmp1, lsr 3
+	ret
+
+L(nonascii_loop):
+	ldp	data1, data2, [src, 16]!
+	sub	tmp1, data1, zeroones
+	orr	tmp2, data1, REP8_7f
+	sub	tmp3, data2, zeroones
+	orr	tmp4, data2, REP8_7f
+	bics	has_nul1, tmp1, tmp2
+	bic	has_nul2, tmp3, tmp4
+	ccmp	has_nul2, 0, 0, eq
+	bne	L(tail)
+	ldp	data1, data2, [src, 16]!
+	sub	tmp1, data1, zeroones
+	orr	tmp2, data1, REP8_7f
+	sub	tmp3, data2, zeroones
+	orr	tmp4, data2, REP8_7f
+	bics	has_nul1, tmp1, tmp2
+	bic	has_nul2, tmp3, tmp4
+	ccmp	has_nul2, 0, 0, eq
+	beq	L(nonascii_loop)
+	b	L(tail)
+
+	/* Load 16 bytes from [srcin & ~15] and force the bytes that precede
+	   srcin to 0x7f, so we ignore any NUL bytes before the string.
+	   Then continue in the aligned loop.  */
+L(page_cross):
+	bic	src, srcin, 15
+	ldp	data1, data2, [src]
+	lsl	tmp1, srcin, 3
+	mov	tmp4, -1
+#ifdef __AARCH64EB__
+	/* Big-endian.	Early bytes are at MSB.	 */
+	lsr	tmp1, tmp4, tmp1	/* Shift (tmp1 & 63).  */
+#else
+	/* Little-endian.  Early bytes are at LSB.  */
+	lsl	tmp1, tmp4, tmp1	/* Shift (tmp1 & 63).  */
+#endif
+	orr	tmp1, tmp1, REP8_80
+	orn	data1, data1, tmp1
+	orn	tmp2, data2, tmp1
+	tst	srcin, 8
+	csel	data1, data1, tmp4, eq
+	csel	data2, data2, tmp2, eq
+	b	L(page_cross_entry)
 
-	orr	data1, data1, tmp2
-	orr	data2a, data2, tmp2
-	csinv	data1, data1, xzr, le
-	csel	data2, data2, data2a, le
-	b	.Lrealigned
 SYM_FUNC_END_PI(strlen)
 EXPORT_SYMBOL_NOKASAN(strlen)

index 2a7ee949ed47..0c0bf5462de0 100644
@@ -1,299 +1,261 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Copyright (C) 2013 ARM Ltd.
- * Copyright (C) 2013 Linaro.
+ * Copyright (c) 2013, 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/strncmp.S
  */
 
 #include <linux/linkage.h>
 #include <asm/assembler.h>
 
-/*
- * compare two strings
+/* Assumptions:
  *
- * 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.
+ * ARMv8-a, AArch64
  */
 
+#define L(label) .L ## label
+
 #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
+#define src1		x0
+#define src2		x1
+#define limit		x2
+#define result		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
+#define data1		x3
+#define data1w		w3
+#define data2		x4
+#define data2w		w4
+#define has_nul		x5
+#define diff		x6
+#define syndrome	x7
+#define tmp1		x8
+#define tmp2		x9
+#define tmp3		x10
+#define zeroones	x11
+#define pos		x12
+#define limit_wd	x13
+#define mask		x14
+#define endloop		x15
+#define count		mask
 
 SYM_FUNC_START_WEAK_PI(strncmp)
-	cbz	limit, .Lret0
+	cbz	limit, L(ret0)
 	eor	tmp1, src1, src2
 	mov	zeroones, #REP8_01
 	tst	tmp1, #7
-	b.ne	.Lmisaligned8
-	ands	tmp1, src1, #7
-	b.ne	.Lmutual_align
+	and	count, src1, #7
+	b.ne	L(misaligned8)
+	cbnz	count, L(mutual_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.  */
+	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:
+	/* 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.  */
+	.p2align 4
+L(loop_aligned):
 	ldr	data1, [src1], #8
 	ldr	data2, [src2], #8
-.Lstart_realigned:
+L(start_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.  */
+	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
+	b.eq	L(loop_aligned)
+	/* End of main loop */
 
-	/*Not reached the limit, must have found the end or a diff.  */
-	tbz	limit_wd, #63, .Lnot_limit
+	/* Not reached the limit, must have found the end or a diff.  */
+	tbz	limit_wd, #63, L(not_limit)
 
 	/* Limit % 8 == 0 => all bytes significant.  */
 	ands	limit, limit, #7
-	b.eq	.Lnot_limit
+	b.eq	L(not_limit)
 
-	lsl	limit, limit, #3    /* Bits -> bytes.  */
+	lsl	limit, limit, #3	/* Bits -> bytes.  */
 	mov	mask, #~0
-CPU_BE( lsr	mask, mask, limit )
-CPU_LE( lsl	mask, mask, limit )
+#ifdef __AARCH64EB__
+	lsr	mask, mask, limit
+#else
+	lsl	mask, mask, limit
+#endif
 	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:
+L(not_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.
-	*/
+#ifndef	__AARCH64EB__
+	rev	syndrome, syndrome
+	rev	data1, data1
+	/* 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
+	rev	data2, data2
 	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.
-	*/
+	/* 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
+#else
+	/* 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.  */
+	cbnz	has_nul, 1f
+	cmp	data1, data2
+	cset	result, ne
+	cneg	result, result, lo
+	ret
+1:
+	/* Re-compute the NUL-byte detection, using a byte-reversed value.  */
+	rev	tmp3, data1
+	sub	tmp1, tmp3, zeroones
+	orr	tmp2, tmp3, #REP8_7f
+	bic	has_nul, tmp1, tmp2
+	rev	has_nul, has_nul
+	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
+#endif
 
-.Lremain8:
-	/* Limit % 8 == 0 => all bytes significant.  */
-	ands	limit, limit, #7
-	b.eq	.Lret0
-.Ltiny8proc:
+L(mutual_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, count, lsl #3	/* 64 - bits(bytes beyond align). */
+	ldr	data2, [src2], #8
+	mov	tmp2, #~0
+	sub	limit_wd, limit, #1	/* limit != 0, so no underflow.  */
+#ifdef __AARCH64EB__
+	/* Big-endian.  Early bytes are at MSB.  */
+	lsl	tmp2, tmp2, tmp3	/* Shift (count & 63).  */
+#else
+	/* Little-endian.  Early bytes are at LSB.  */
+	lsr	tmp2, tmp2, tmp3	/* Shift (count & 63).  */
+#endif
+	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, count
+	add	tmp3, tmp3, count
+	orr	data1, data1, tmp2
+	orr	data2, data2, tmp2
+	add	limit_wd, limit_wd, tmp3, lsr #3
+	b	L(start_realigned)
+
+	.p2align 4
+	/* Don't bother with dwords for up to 16 bytes.  */
+L(misaligned8):
+	cmp	limit, #16
+	b.hs	L(try_misaligned_words)
+
+L(byte_loop):
+	/* Perhaps we can do better than this.  */
 	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
+	ccmp	data1w, #1, #0, hi	/* NZCV = 0b0000.  */
+	ccmp	data1w, data2w, #0, cs	/* NZCV = 0b0000.  */
+	b.eq	L(byte_loop)
+L(done):
 	sub	result, data1, data2
 	ret
+	/* Align the SRC1 to a dword by doing a bytewise compare and then do
+	   the dword loop.  */
+L(try_misaligned_words):
+	lsr	limit_wd, limit, #3
+	cbz	count, L(do_misaligned)
 
-.Lret0:
+	neg	count, count
+	and	count, count, #7
+	sub	limit, limit, count
+	lsr	limit_wd, limit, #3
+
+L(page_end_loop):
+	ldrb	data1w, [src1], #1
+	ldrb	data2w, [src2], #1
+	cmp	data1w, #1
+	ccmp	data1w, data2w, #0, cs	/* NZCV = 0b0000.  */
+	b.ne	L(done)
+	subs	count, count, #1
+	b.hi	L(page_end_loop)
+
+L(do_misaligned):
+	/* Prepare ourselves for the next page crossing.  Unlike the aligned
+	   loop, we fetch 1 less dword because we risk crossing bounds on
+	   SRC2.  */
+	mov	count, #8
+	subs	limit_wd, limit_wd, #1
+	b.lo	L(done_loop)
+L(loop_misaligned):
+	and	tmp2, src2, #0xff8
+	eor	tmp2, tmp2, #0xff8
+	cbz	tmp2, L(page_end_loop)
+
+	ldr	data1, [src1], #8
+	ldr	data2, [src2], #8
+	sub	tmp1, data1, zeroones
+	orr	tmp2, data1, #REP8_7f
+	eor	diff, data1, data2	/* Non-zero if differences found.  */
+	bics	has_nul, tmp1, tmp2	/* Non-zero if NUL terminator.  */
+	ccmp	diff, #0, #0, eq
+	b.ne	L(not_limit)
+	subs	limit_wd, limit_wd, #1
+	b.pl	L(loop_misaligned)
+
+L(done_loop):
+	/* We found a difference or a NULL before the limit was reached.  */
+	and	limit, limit, #7
+	cbz	limit, L(not_limit)
+	/* Read the last word.  */
+	sub	src1, src1, 8
+	sub	src2, src2, 8
+	ldr	data1, [src1, limit]
+	ldr	data2, [src2, limit]
+	sub	tmp1, data1, zeroones
+	orr	tmp2, data1, #REP8_7f
+	eor	diff, data1, data2	/* Non-zero if differences found.  */
+	bics	has_nul, tmp1, tmp2	/* Non-zero if NUL terminator.  */
+	ccmp	diff, #0, #0, eq
+	b.ne	L(not_limit)
+
+L(ret0):
 	mov	result, #0
 	ret
+
 SYM_FUNC_END_PI(strncmp)
 EXPORT_SYMBOL_NOKASAN(strncmp)

index d31e1169d9b8..01c596aa539c 100644
@@ -1,7 +1,7 @@
 # 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
 

296 lines not on this page · raw message

189 lines not on this page · raw message

index edf6b970a277..7c2276fdab54 100644
@@ -1,9 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Based on arch/arm/lib/memchr.S
- *
- * Copyright (C) 1995-2000 Russell King
- * Copyright (C) 2013 ARM Ltd.
+ * Copyright (C) 2021 Arm Ltd.
  */
 
 #include <linux/linkage.h>

@@ -19,16 +16,60 @@
  * Returns:
  *	x0 - address of first occurrence of 'c' or 0
  */
+
+#define L(label) .L ## label
+
+#define REP8_01 0x0101010101010101
+#define REP8_7f 0x7f7f7f7f7f7f7f7f
+
+#define srcin		x0
+#define chrin		w1
+#define cntin		x2
+
+#define result		x0
+
+#define wordcnt		x3
+#define rep01		x4
+#define repchr		x5
+#define cur_word	x6
+#define cur_byte	w6
+#define tmp		x7
+#define tmp2		x8
+
+	.p2align 4
+	nop
 SYM_FUNC_START_WEAK_PI(memchr)
-	and	w1, w1, #0xff
-1:	subs	x2, x2, #1
-	b.mi	2f
-	ldrb	w3, [x0], #1
-	cmp	w3, w1
-	b.ne	1b
-	sub	x0, x0, #1
+	and	chrin, chrin, #0xff
+	lsr	wordcnt, cntin, #3
+	cbz	wordcnt, L(byte_loop)
+	mov	rep01, #REP8_01
+	mul	repchr, x1, rep01
+	and	cntin, cntin, #7
+L(word_loop):
+	ldr	cur_word, [srcin], #8
+	sub	wordcnt, wordcnt, #1
+	eor	cur_word, cur_word, repchr
+	sub	tmp, cur_word, rep01
+	orr	tmp2, cur_word, #REP8_7f
+	bics	tmp, tmp, tmp2
+	b.ne	L(found_word)
+	cbnz	wordcnt, L(word_loop)
+L(byte_loop):
+	cbz	cntin, L(not_found)
+	ldrb	cur_byte, [srcin], #1
+	sub	cntin, cntin, #1
+	cmp	cur_byte, chrin
+	b.ne	L(byte_loop)
+	sub	srcin, srcin, #1
 	ret
-2:	mov	x0, #0
+L(found_word):
+CPU_LE(	rev	tmp, tmp)
+	clz	tmp, tmp
+	sub	tmp, tmp, #64
+	add	result, srcin, tmp, asr #3
+	ret
+L(not_found):
+	mov	result, #0
 	ret
 SYM_FUNC_END_PI(memchr)
 EXPORT_SYMBOL_NOKASAN(memchr)

index af9afcbec92c..1005345b4066 100644
@@ -1,12 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Based on arch/arm/lib/clear_user.S
- *
- * Copyright (C) 2012 ARM Ltd.
+ * Copyright (C) 2021 Arm Ltd.
  */
-#include <linux/linkage.h>
 
-#include <asm/asm-uaccess.h>
+#include <linux/linkage.h>
 #include <asm/assembler.h>
 
 	.text

@@ -19,25 +16,30 @@
  *
  * Alignment fixed up by hardware.
  */
+	.p2align 4
 SYM_FUNC_START(__arch_clear_user)
-	mov	x2, x1			// save the size for fixup return
+	add	x2, x0, x1
 	subs	x1, x1, #8
 	b.mi	2f
 1:
-user_ldst 9f, sttr, xzr, x0, 8
+USER(9f, sttr	xzr, [x0])
+	add	x0, x0, #8
 	subs	x1, x1, #8
-	b.pl	1b
-2:	adds	x1, x1, #4
-	b.mi	3f
-user_ldst 9f, sttr, wzr, x0, 4
-	sub	x1, x1, #4
-3:	adds	x1, x1, #2
-	b.mi	4f
-user_ldst 9f, sttrh, wzr, x0, 2
-	sub	x1, x1, #2
-4:	adds	x1, x1, #1
-	b.mi	5f
-user_ldst 9f, sttrb, wzr, x0, 0
+	b.hi	1b
+USER(9f, sttr	xzr, [x2, #-8])
+	mov	x0, #0
+	ret
+
+2:	tbz	x1, #2, 3f
+USER(9f, sttr	wzr, [x0])
+USER(9f, sttr	wzr, [x2, #-4])
+	mov	x0, #0
+	ret
+
+3:	tbz	x1, #1, 4f
+USER(9f, sttrh	wzr, [x0])
+4:	tbz	x1, #0, 5f
+USER(9f, sttrb	wzr, [x2, #-1])
 5:	mov	x0, #0
 	ret
 SYM_FUNC_END(__arch_clear_user)

@@ -45,6 +47,6 @@ EXPORT_SYMBOL(__arch_clear_user)
 
 	.section .fixup,"ax"
 	.align	2
-9:	mov	x0, x2			// return the original size
+9:	sub	x0, x2, x0
 	ret
 	.previous

index 1005345b4066..7ef553ec2677 100644
@@ -32,12 +32,14 @@ USER(9f, sttr       xzr, [x2, #-8])
 
 2:     tbz     x1, #2, 3f
 USER(9f, sttr  wzr, [x0])
+       add     x0, x0, #4
 USER(9f, sttr  wzr, [x2, #-4])
        mov     x0, #0
        ret
 
 3:     tbz     x1, #1, 4f
 USER(9f, sttrh wzr, [x0])
+       add     x0, x0, #2
 4:     tbz     x1, #0, 5f
 USER(9f, sttrb wzr, [x2, #-1])
 5:     mov     x0, #0

index af9afcbec92c..d30c03f6caed 100644
@@ -1,12 +1,9 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Based on arch/arm/lib/clear_user.S
- *
- * Copyright (C) 2012 ARM Ltd.
+ * Copyright (C) 2021 Arm Ltd.
  */
-#include <linux/linkage.h>
 
-#include <asm/asm-uaccess.h>
+#include <linux/linkage.h>
 #include <asm/assembler.h>
 
 	.text

@@ -19,25 +16,30 @@
  *
  * Alignment fixed up by hardware.
  */
+	.p2align 4
 SYM_FUNC_START(__arch_clear_user)
-	mov	x2, x1			// save the size for fixup return
+	add	x2, x0, x1
 	subs	x1, x1, #8
 	b.mi	2f
 1:
-user_ldst 9f, sttr, xzr, x0, 8
+USER(9f, sttr	xzr, [x0])
+	add	x0, x0, #8
 	subs	x1, x1, #8
-	b.pl	1b
-2:	adds	x1, x1, #4
-	b.mi	3f
-user_ldst 9f, sttr, wzr, x0, 4
-	sub	x1, x1, #4
-3:	adds	x1, x1, #2
-	b.mi	4f
-user_ldst 9f, sttrh, wzr, x0, 2
-	sub	x1, x1, #2
-4:	adds	x1, x1, #1
-	b.mi	5f
-user_ldst 9f, sttrb, wzr, x0, 0
+	b.hi	1b
+USER(9f, sttr	xzr, [x2, #-8])
+	mov	x0, #0
+	ret
+
+2:	tbz	x1, #2, 3f
+USER(9f, sttr	wzr, [x0])
+USER(8f, sttr	wzr, [x2, #-4])
+	mov	x0, #0
+	ret
+
+3:	tbz	x1, #1, 4f
+USER(9f, sttrh	wzr, [x0])
+4:	tbz	x1, #0, 5f
+USER(7f, sttrb	wzr, [x2, #-1])
 5:	mov	x0, #0
 	ret
 SYM_FUNC_END(__arch_clear_user)

@@ -45,6 +47,8 @@ EXPORT_SYMBOL(__arch_clear_user)
 
 	.section .fixup,"ax"
 	.align	2
-9:	mov	x0, x2			// return the original size
+7:	sub	x0, x2, #5	// Adjust for faulting on the final byte...
+8:	add	x0, x0, #4	// ...or the second word of the 4-7 byte case
+9:	sub	x0, x2, x0
 	ret
 	.previous