linux-kernel - [PATCH 5/5] ARCv2: LIB: MEMCPY: fixed and optimised routine

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Date:   Tue, 29 Jan 2019 13:49:42 +0300
From:   Eugeniy Paltsev <eugeniy.paltsev@...opsys.com>
To:     linux-snps-arc@...ts.infradead.org,
        Vineet Gupta <vineet.gupta1@...opsys.com>
Cc:     linux-kernel@...r.kernel.org,
        Alexey Brodkin <alexey.brodkin@...opsys.com>,
        Eugeniy Paltsev <eugeniy.paltsev@...opsys.com>
Subject: [PATCH 5/5] ARCv2: LIB: MEMCPY: fixed and optimised routine

Optimise code to use efficient unaligned memory access which is
available on ARCv2. This allows us to really simplify memcpy code
and speed up the code one and a half times (in case of unaligned
source or destination).

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
---
 arch/arc/Kconfig                      |  4 +++
 arch/arc/lib/Makefile                 |  5 +++-
 arch/arc/lib/memcpy-archs-unaligned.S | 46 +++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 arch/arc/lib/memcpy-archs-unaligned.S

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index a1d976c612a6..88f1a3205b8f 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -396,6 +396,10 @@ config ARC_USE_UNALIGNED_MEM_ACCESS
 	  which is disabled by default. Enable unaligned access in
 	  hardware and use it in software.
 
+#dummy symbol for using in makefile
+config ARC_NO_UNALIGNED_MEM_ACCESS
+	def_bool !ARC_USE_UNALIGNED_MEM_ACCESS
+
 config ARC_HAS_LL64
 	bool "Insn: 64bit LDD/STD"
 	help
diff --git a/arch/arc/lib/Makefile b/arch/arc/lib/Makefile
index b1656d156097..59cc8b61342e 100644
--- a/arch/arc/lib/Makefile
+++ b/arch/arc/lib/Makefile
@@ -8,4 +8,7 @@
 lib-y	:= strchr-700.o strcpy-700.o strlen.o memcmp.o
 
 lib-$(CONFIG_ISA_ARCOMPACT)	+= memcpy-700.o memset.o strcmp.o
-lib-$(CONFIG_ISA_ARCV2)		+= memcpy-archs.o memset-archs.o strcmp-archs.o
+lib-$(CONFIG_ISA_ARCV2)		+= memset-archs.o strcmp-archs.o
+
+lib-$(CONFIG_ARC_NO_UNALIGNED_MEM_ACCESS)	+= memcpy-archs.o
+lib-$(CONFIG_ARC_USE_UNALIGNED_MEM_ACCESS)	+= memcpy-archs-unaligned.o
diff --git a/arch/arc/lib/memcpy-archs-unaligned.S b/arch/arc/lib/memcpy-archs-unaligned.S
new file mode 100644
index 000000000000..e09b51d4de70
--- /dev/null
+++ b/arch/arc/lib/memcpy-archs-unaligned.S
@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+//
+// ARCv2 memcpy implementation optimized for unaligned memory access using.
+//
+// Copyright (C) 2019 Synopsys
+// Author: Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>
+
+#include <linux/linkage.h>
+
+#ifdef CONFIG_ARC_HAS_LL64
+# define LOADX(DST,RX)		ldd.ab	DST, [RX, 8]
+# define STOREX(SRC,RX)		std.ab	SRC, [RX, 8]
+# define ZOLSHFT		5
+# define ZOLAND			0x1F
+#else
+# define LOADX(DST,RX)		ld.ab	DST, [RX, 4]
+# define STOREX(SRC,RX)		st.ab	SRC, [RX, 4]
+# define ZOLSHFT		4
+# define ZOLAND			0xF
+#endif
+
+ENTRY_CFI(memcpy)
+	mov	r3, r0		; don;t clobber ret val
+
+	lsr.f	lp_count, r2, ZOLSHFT
+	lpnz	@.Lcopy32_64bytes
+	;; LOOP START
+	LOADX	(r6, r1)
+	LOADX	(r8, r1)
+	LOADX	(r10, r1)
+	LOADX	(r4, r1)
+	STOREX	(r6, r3)
+	STOREX	(r8, r3)
+	STOREX	(r10, r3)
+	STOREX	(r4, r3)
+.Lcopy32_64bytes:
+
+	and.f	lp_count, r2, ZOLAND ;Last remaining 31 bytes
+	lpnz	@.Lcopyremainingbytes
+	;; LOOP START
+	ldb.ab	r5, [r1, 1]
+	stb.ab	r5, [r3, 1]
+.Lcopyremainingbytes:
+
+	j	[blink]
+END_CFI(memcpy)
-- 
2.14.5