linux-kernel - [PATCH v2 3/6] powerpc32: memset(0): use cacheable

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Message-Id: <bcab8e1bde2b7b82c60be00ea5f4bb14afcce764.1432012060.git.christophe.leroy@c-s.fr>
Date:	Tue, 19 May 2015 12:07:50 +0200 (CEST)
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>, scottwood@...escale.com
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
Subject: [PATCH v2 3/6] powerpc32: memset(0): use cacheable_memzero

cacheable_memzero uses dcbz instruction and is more efficient than
memset(0) when the destination is in RAM

This patch renames memset as generic_memset, and defines memset
as a prolog to cacheable_memzero. This prolog checks if the byte
to set is 0. If not, it falls back to generic_memcpy()

cacheable_memzero disappears as it is not referenced anywhere anymore

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
---
 arch/powerpc/lib/copy_32.S | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index 55f19f9..0b4f954 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -74,9 +74,9 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
  * to set them to zero.  This requires that the destination
  * area is cacheable.  -- paulus
  */
-_GLOBAL(cacheable_memzero)
-	mr	r5,r4
-	li	r4,0
+_GLOBAL(memset)
+	cmplwi	r4,0
+	bne-	generic_memset
 	addi	r6,r3,-4
 	cmplwi	0,r5,4
 	blt	7f
@@ -117,7 +117,7 @@ _GLOBAL(cacheable_memzero)
 	bdnz	8b
 	blr
 
-_GLOBAL(memset)
+_GLOBAL(generic_memset)
 	rlwimi	r4,r4,8,16,23
 	rlwimi	r4,r4,16,0,15
 	addi	r6,r3,-4
-- 
2.1.0

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