Message-Id: <1430267932-17730-1-git-send-email-fkan@apm.com>
Date:	Tue, 28 Apr 2015 17:38:52 -0700
From:	Feng Kan <fkan@....com>
To:	patches@....com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	philipp.tomsich@...obroma-systems.com, dann.frazier@...onical.com,
	tim.gardner@...onical.com, craig.magina@...onical.com
Cc:	Feng Kan <fkan@....com>
Subject: [PATCH V3] arm64: optimized copy_to_user and copy_from_user assembly code

Using the glibc cortex string work work authored by Linaro as base to
create new copy to/from user kernel routine.

Iperf performance increase:
		-l (size)		1 core result
Optimized 	64B			44-51Mb/s
		1500B			4.9Gb/s
		30000B			16.2Gb/s
Original	64B			34-50.7Mb/s
		1500B			4.7Gb/s
		30000B			14.5Gb/s

Signed-off-by: Feng Kan <fkan@....com>
---
 arch/arm64/lib/copy_from_user.S |  92 +++++++++++------
 arch/arm64/lib/copy_template.S  | 213 ++++++++++++++++++++++++++++++++++++++++
 arch/arm64/lib/copy_to_user.S   |  56 ++++++-----
 3 files changed, 302 insertions(+), 59 deletions(-)
 create mode 100644 arch/arm64/lib/copy_template.S

diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 5e27add..0e79ed9 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -15,7 +15,6 @@
  */
 
 #include <linux/linkage.h>
-#include <asm/assembler.h>
 
 /*
  * Copy from user space to a kernel buffer (alignment handled by the hardware)
@@ -28,39 +27,68 @@
  *	x0 - bytes not copied
  */
 ENTRY(__copy_from_user)
-	add	x4, x1, x2			// upper user buffer boundary
-	subs	x2, x2, #8
-	b.mi	2f
-1:
-USER(9f, ldr	x3, [x1], #8	)
-	subs	x2, x2, #8
-	str	x3, [x0], #8
-	b.pl	1b
-2:	adds	x2, x2, #4
-	b.mi	3f
-USER(9f, ldr	w3, [x1], #4	)
-	sub	x2, x2, #4
-	str	w3, [x0], #4
-3:	adds	x2, x2, #2
-	b.mi	4f
-USER(9f, ldrh	w3, [x1], #2	)
-	sub	x2, x2, #2
-	strh	w3, [x0], #2
-4:	adds	x2, x2, #1
-	b.mi	5f
-USER(9f, ldrb	w3, [x1]	)
-	strb	w3, [x0]
-5:	mov	x0, #0
-	ret
+#include "copy_template.S"
 ENDPROC(__copy_from_user)
 
 	.section .fixup,"ax"
-	.align	2
-9:	sub	x2, x4, x1
-	mov	x3, x2
-10:	strb	wzr, [x0], #1			// zero remaining buffer space
-	subs	x3, x3, #1
-	b.ne	10b
-	mov	x0, x2				// bytes not copied
+	.align    2
+9:
+	/*
+	 * count is accurate
+	 * dst is accurate
+	 */
+	mov	x0, count
+	sub	dst, dst, tmp1
+	b	.Lfinalize
+
+10:
+	/*
+	 * count is in the last 15 bytes
+	 * dst is somewhere in there
+	 */
+	mov	x0, count
+	sub	dst, limit, count
+	b	.Lfinalize
+11:
+	/*
+	 * count over counted by tmp2
+	 * dst could be anywhere in there
+	 */
+	add	x0, count, tmp2
+	sub	dst, limit, x0
+	b	.Lfinalize
+12:
+	/*
+	 * (count + 64) bytes remain
+	 * dst is accurate
+	 */
+	adds	x0, count, #64
+	b	.Lfinalize
+13:
+	/*
+	 * (count + 128) bytes remain
+	 * dst is pre-biased to (dst + 16)
+	 */
+	adds	x0, count, #128
+	add	dst, dst, #16
+	b	.Lfinalize
+14:
+	/*
+	 * (count + 64) bytes remain
+	 * dst is pre-biased to (dst + 16)
+	 */
+	adds	x0, count, #64
+	add	dst, dst, #16
+
+.Lfinalize:
+	/*
+	 * Zeroize remaining destination-buffer
+	 */
+	mov	count, x0
+20:
+	/* Zero remaining buffer space */
+	strb	wzr, [dst], #1
+	subs	count, count, #1
+	b.ne	20b
 	ret
 	.previous
diff --git a/arch/arm64/lib/copy_template.S b/arch/arm64/lib/copy_template.S
new file mode 100644
index 0000000..7a22c6b
--- /dev/null
+++ b/arch/arm64/lib/copy_template.S
@@ -0,0 +1,213 @@
+/*
+ * Copyright (c) 2013, Applied Micro Circuits Corporation
+ * Copyright (c) 2012-2013, Linaro Limited
+ *
+ * Author: Feng Kan <fkan@....com>
+ * Author: Philipp Tomsich <philipp.tomsich@...obroma-systems.com>
+ *
+ * The code is adopted from the memcpy routine by Linaro Limited.
+ *
+ * This file is free software: you may copy, redistribute and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This file 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/>.
+ *
+ * This file incorporates work covered by the following copyright and
+ * permission notice:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *      1 Redistributions of source code must retain the above copyright
+ *        notice, this list of conditions and the following disclaimer.
+ *      2 Redistributions in binary form must reproduce the above copyright
+ *        notice, this list of conditions and the following disclaimer in the
+ *        documentation and/or other materials provided with the distribution.
+ *      3 Neither the name of the Linaro nor the
+ *        names of its contributors may be used to endorse or promote products
+ *        derived from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *  HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include <asm/assembler.h>
+#include <asm/cache.h>
+
+dstin	.req x0
+src	.req x1
+count	.req x2
+tmp1	.req x3
+tmp1w	.req w3
+tmp2	.req x4
+tmp2w	.req w4
+limit	.req x5
+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
+
+	mov	dst, dstin
+	add	limit, dst, count
+	cmp	count, #16
+	b.lo	.Ltail15
+
+	/*
+	 * We don't much care about the alignment of DST, but we want SRC
+	 * to be 128-bit (16 byte) aligned so that we don't cross cache line
+	 * boundaries on both loads and stores.
+	 */
+	ands	tmp2, src, #15
+	b.eq	.LSrcAligned
+	sub	count, count, tmp2
+
+	tbz	tmp2, #0, 1f
+	USER(11f, ldrb	tmp1w, [src], #1)
+	USER(11f, strb	tmp1w, [dst], #1)
+1:
+	tbz	tmp2, #1, 2f
+	USER(11f, ldrh	tmp1w, [src], #2)
+	USER(11f, strh	tmp1w, [dst], #2)
+2:
+	tbz	tmp2, #2, 3f
+	USER(11f, ldr	tmp1w, [src], #4)
+	USER(11f, str	tmp1w, [dst], #4)
+3:
+	tbz	tmp2, #3, .LSrcAligned
+	USER(11f, ldr	tmp1, [src], #8)
+	USER(11f, str	tmp1, [dst], #8)
+
+.LSrcAligned:
+	/* There may be less than 63 bytes to go now.  */
+	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
+	add	dst, dst, tmp1
+	add	src, src, tmp1
+	cmp	tmp1w, #0x20
+	b.eq	1f
+	b.lt	2f
+	USER(9f, ldp A_l, A_h, [src, #-48])
+	USER(9f, stp A_l, A_h, [dst, #-48])
+1:
+	USER(9f, ldp A_l, A_h, [src, #-32])
+	USER(9f, stp A_l, A_h, [dst, #-32])
+2:
+	USER(9f, ldp A_l, A_h, [src, #-16])
+	USER(9f, stp A_l, A_h, [dst, #-16])
+
+.Ltail15:
+	ands	count, count, #15
+	beq	.Lsuccess	/* Quick exit if we are done*/
+	/*
+	 * Copy up to 15 bytes of data.  Does not assume additional data
+	 * being copied.
+	 */
+	tbz	count, #3, 1f
+	USER(10f, ldr tmp1, [src], #8)
+	USER(10f, str tmp1, [dst], #8)
+1:
+	tbz	count, #2, 1f
+	USER(10f, ldr tmp1w, [src], #4)
+	USER(10f, str tmp1w, [dst], #4)
+1:
+	tbz	count, #1, 1f
+	USER(10f, ldrh tmp1w, [src], #2)
+	USER(10f, strh tmp1w, [dst], #2)
+1:
+	tbz	count, #0, 1f
+	USER(10f, ldrb tmp1w, [src], #1)
+	USER(10f, strb tmp1w, [dst], #1)
+1:
+	b	.Lsuccess
+
+.Lcpy_over64:
+	subs	count, count, #128
+	b.ge	.Lcpy_body_large
+	/*
+	 * Less than 128 bytes to copy, so handle 64 here and then jump
+	 * to the tail.
+	 */
+	adds	count, count, #64
+	USER(12f, ldp A_l, A_h, [src])
+	USER(12f, ldp B_l, B_h, [src, #16])
+	USER(12f, ldp C_l, C_h, [src, #32])
+	USER(12f, ldp D_l, D_h, [src, #48])
+	USER(12f, stp A_l, A_h, [dst])
+	USER(12f, stp B_l, B_h, [dst, #16])
+	USER(12f, stp C_l, C_h, [dst, #32])
+	USER(12f, stp D_l, D_h, [dst, #48])
+	add	src, src, #64
+	add	dst, dst, #64
+	tst	count, #0x3f
+	b.ne	.Ltail63
+	b	.Lsuccess
+
+	/*
+	 * 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:
+	/* There are at least 128 bytes to copy.  */
+	sub	dst, dst, #16			/* Pre-bias.  */
+	USER(13f, ldp A_l, A_h, [src, #0])
+	USER(13f, ldp B_l, B_h, [src, #16])
+	USER(13f, ldp C_l, C_h, [src, #32])
+	USER(13f, ldp D_l, D_h, [src, #48]!)	/* src += 64 - Pre-bias. */
+1:
+	USER(13f, stp A_l, A_h, [dst, #16])
+	USER(13f, ldp A_l, A_h, [src, #16])
+	USER(13f, stp B_l, B_h, [dst, #32])
+	USER(13f, ldp B_l, B_h, [src, #32])
+	USER(13f, stp C_l, C_h, [dst, #48])
+	USER(13f, ldp C_l, C_h, [src, #48])
+	USER(14f, stp D_l, D_h, [dst, #64]!)
+	USER(14f, ldp D_l, D_h, [src, #64]!)
+	subs	count, count, #64
+	b.ge	1b
+	USER(13f, stp A_l, A_h, [dst, #16])
+	USER(13f, stp B_l, B_h, [dst, #32])
+	USER(13f, stp C_l, C_h, [dst, #48])
+	USER(13f, stp D_l, D_h, [dst, #64])
+	add	src, src, #16
+	add	dst, dst, #80		/* 64 bytes + 16 prebias */
+	adds	count, count, #64
+	tst	count, #0x3f
+	b.ne	.Ltail63
+.Lsuccess:
+	/* Nothing left to copy */
+	mov	x0, #0
+	ret
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index a0aeeb9..2ce36de 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -15,7 +15,6 @@
  */
 
 #include <linux/linkage.h>
-#include <asm/assembler.h>
 
 /*
  * Copy to user space from a kernel buffer (alignment handled by the hardware)
@@ -28,34 +27,37 @@
  *	x0 - bytes not copied
  */
 ENTRY(__copy_to_user)
-	add	x4, x0, x2			// upper user buffer boundary
-	subs	x2, x2, #8
-	b.mi	2f
-1:
-	ldr	x3, [x1], #8
-	subs	x2, x2, #8
-USER(9f, str	x3, [x0], #8	)
-	b.pl	1b
-2:	adds	x2, x2, #4
-	b.mi	3f
-	ldr	w3, [x1], #4
-	sub	x2, x2, #4
-USER(9f, str	w3, [x0], #4	)
-3:	adds	x2, x2, #2
-	b.mi	4f
-	ldrh	w3, [x1], #2
-	sub	x2, x2, #2
-USER(9f, strh	w3, [x0], #2	)
-4:	adds	x2, x2, #1
-	b.mi	5f
-	ldrb	w3, [x1]
-USER(9f, strb	w3, [x0]	)
-5:	mov	x0, #0
-	ret
+#include "copy_template.S"
 ENDPROC(__copy_to_user)
 
 	.section .fixup,"ax"
-	.align	2
-9:	sub	x0, x4, x0			// bytes not copied
+	.align    2
+9:
+10:
+	/*
+	 * count is accurate
+	 */
+	mov	x0, count
+	b	.Lfinalize
+11:
+	/*
+	 * count is over accounted by tmp2
+	 */
+	add	x0, count, tmp2
+	b	.Lfinalize
+12:
+14:
+	/*
+	 * (count + 64) bytes remain
+	 * dst is accurate
+	 */
+	adds	x0, count, #64
+	b	.Lfinalize
+13:
+	/*
+	 * (count + 128) bytes remain
+	 */
+	add	x0, count, #128
+.Lfinalize:
 	ret
 	.previous
-- 
1.9.1

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