[PATCH 0/4] powerpc32: use cacheable alternatives of memcpy and memset

[PATCH 0/4] powerpc32: use cacheable alternatives of memcpy and memset

[Christophe Leroy]

This patchset implements use of cacheable versions of memset and
memcpy when the len is greater than the cacheline size and the
destination is in RAM.

On MPC885, we observe a 7% rate increase on FTP transfer

Christophe Leroy (4):
  Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero
    functions"
  powerpc32: swap r4 and r5 in cacheable_memzero
  powerpc32: memset(0): use cacheable_memzero
  powerpc32: memcpy: use cacheable_memcpy

 arch/powerpc/lib/copy_32.S | 148 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)

-- 
2.1.0

[PATCH 0/4] powerpc32: use cacheable alternatives of memcpy and memset

[Christophe Leroy]

This patchset implements use of cacheable versions of memset and
memcpy when the len is greater than the cacheline size and the
destination is in RAM.

On MPC885, we observe a 7% rate increase on FTP transfer

Christophe Leroy (4):
  Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero
    functions"
  powerpc32: swap r4 and r5 in cacheable_memzero
  powerpc32: memset(0): use cacheable_memzero
  powerpc32: memcpy: use cacheable_memcpy

 arch/powerpc/lib/copy_32.S | 148 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)

-- 
2.1.0

[PATCH 1/4] Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero functions"

[Christophe Leroy]

This partially reverts
commit 'powerpc: Remove duplicate cacheable_memcpy/memzero functions
("f909a35bdfb7cb350d078a2cf888162eeb20381c")'

Functions cacheable_memcpy/memzero are more efficient than
memcpy/memset as they use the dcbz instruction which avoids refill
of the cacheline with the data that we will overwrite.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 127 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index 6813f80..55f19f9 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -69,6 +69,54 @@ CACHELINE_BYTES = L1_CACHE_BYTES
 LG_CACHELINE_BYTES = L1_CACHE_SHIFT
 CACHELINE_MASK = (L1_CACHE_BYTES-1)
 
+/*
+ * Use dcbz on the complete cache lines in the destination
+ * to set them to zero.  This requires that the destination
+ * area is cacheable.  -- paulus
+ */
+_GLOBAL(cacheable_memzero)
+	mr	r5,r4
+	li	r4,0
+	addi	r6,r3,-4
+	cmplwi	0,r5,4
+	blt	7f
+	stwu	r4,4(r6)
+	beqlr
+	andi.	r0,r6,3
+	add	r5,r0,r5
+	subf	r6,r0,r6
+	clrlwi	r7,r6,32-LG_CACHELINE_BYTES
+	add	r8,r7,r5
+	srwi	r9,r8,LG_CACHELINE_BYTES
+	addic.	r9,r9,-1	/* total number of complete cachelines */
+	ble	2f
+	xori	r0,r7,CACHELINE_MASK & ~3
+	srwi.	r0,r0,2
+	beq	3f
+	mtctr	r0
+4:	stwu	r4,4(r6)
+	bdnz	4b
+3:	mtctr	r9
+	li	r7,4
+10:	dcbz	r7,r6
+	addi	r6,r6,CACHELINE_BYTES
+	bdnz	10b
+	clrlwi	r5,r8,32-LG_CACHELINE_BYTES
+	addi	r5,r5,4
+2:	srwi	r0,r5,2
+	mtctr	r0
+	bdz	6f
+1:	stwu	r4,4(r6)
+	bdnz	1b
+6:	andi.	r5,r5,3
+7:	cmpwi	0,r5,0
+	beqlr
+	mtctr	r5
+	addi	r6,r6,3
+8:	stbu	r4,1(r6)
+	bdnz	8b
+	blr
+
 _GLOBAL(memset)
 	rlwimi	r4,r4,8,16,23
 	rlwimi	r4,r4,16,0,15
@@ -94,6 +142,85 @@ _GLOBAL(memset)
 	bdnz	8b
 	blr
 
+/*
+ * This version uses dcbz on the complete cache lines in the
+ * destination area to reduce memory traffic.  This requires that
+ * the destination area is cacheable.
+ * We only use this version if the source and dest don't overlap.
+ * -- paulus.
+ */
+_GLOBAL(cacheable_memcpy)
+	add	r7,r3,r5		/* test if the src & dst overlap */
+	add	r8,r4,r5
+	cmplw	0,r4,r7
+	cmplw	1,r3,r8
+	crand	0,0,4			/* cr0.lt &= cr1.lt */
+	blt	memcpy			/* if regions overlap */
+
+	addi	r4,r4,-4
+	addi	r6,r3,-4
+	neg	r0,r3
+	andi.	r0,r0,CACHELINE_MASK	/* # bytes to start of cache line */
+	beq	58f
+
+	cmplw	0,r5,r0			/* is this more than total to do? */
+	blt	63f			/* if not much to do */
+	andi.	r8,r0,3			/* get it word-aligned first */
+	subf	r5,r0,r5
+	mtctr	r8
+	beq+	61f
+70:	lbz	r9,4(r4)		/* do some bytes */
+	stb	r9,4(r6)
+	addi	r4,r4,1
+	addi	r6,r6,1
+	bdnz	70b
+61:	srwi.	r0,r0,2
+	mtctr	r0
+	beq	58f
+72:	lwzu	r9,4(r4)		/* do some words */
+	stwu	r9,4(r6)
+	bdnz	72b
+
+58:	srwi.	r0,r5,LG_CACHELINE_BYTES /* # complete cachelines */
+	clrlwi	r5,r5,32-LG_CACHELINE_BYTES
+	li	r11,4
+	mtctr	r0
+	beq	63f
+53:
+	dcbz	r11,r6
+	COPY_16_BYTES
+#if L1_CACHE_BYTES >= 32
+	COPY_16_BYTES
+#if L1_CACHE_BYTES >= 64
+	COPY_16_BYTES
+	COPY_16_BYTES
+#if L1_CACHE_BYTES >= 128
+	COPY_16_BYTES
+	COPY_16_BYTES
+	COPY_16_BYTES
+	COPY_16_BYTES
+#endif
+#endif
+#endif
+	bdnz	53b
+
+63:	srwi.	r0,r5,2
+	mtctr	r0
+	beq	64f
+30:	lwzu	r0,4(r4)
+	stwu	r0,4(r6)
+	bdnz	30b
+
+64:	andi.	r0,r5,3
+	mtctr	r0
+	beq+	65f
+40:	lbz	r0,4(r4)
+	stb	r0,4(r6)
+	addi	r4,r4,1
+	addi	r6,r6,1
+	bdnz	40b
+65:	blr
+
 _GLOBAL(memmove)
 	cmplw	0,r3,r4
 	bgt	backwards_memcpy
-- 
2.1.0

[PATCH 1/4] Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero functions"

[Christophe Leroy]

This partially reverts
commit 'powerpc: Remove duplicate cacheable_memcpy/memzero functions
("f909a35bdfb7cb350d078a2cf888162eeb20381c")'

Functions cacheable_memcpy/memzero are more efficient than
memcpy/memset as they use the dcbz instruction which avoids refill
of the cacheline with the data that we will overwrite.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 127 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index 6813f80..55f19f9 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -69,6 +69,54 @@ CACHELINE_BYTES = L1_CACHE_BYTES
 LG_CACHELINE_BYTES = L1_CACHE_SHIFT
 CACHELINE_MASK = (L1_CACHE_BYTES-1)
 
+/*
+ * Use dcbz on the complete cache lines in the destination
+ * to set them to zero.  This requires that the destination
+ * area is cacheable.  -- paulus
+ */
+_GLOBAL(cacheable_memzero)
+	mr	r5,r4
+	li	r4,0
+	addi	r6,r3,-4
+	cmplwi	0,r5,4
+	blt	7f
+	stwu	r4,4(r6)
+	beqlr
+	andi.	r0,r6,3
+	add	r5,r0,r5
+	subf	r6,r0,r6
+	clrlwi	r7,r6,32-LG_CACHELINE_BYTES
+	add	r8,r7,r5
+	srwi	r9,r8,LG_CACHELINE_BYTES
+	addic.	r9,r9,-1	/* total number of complete cachelines */
+	ble	2f
+	xori	r0,r7,CACHELINE_MASK & ~3
+	srwi.	r0,r0,2
+	beq	3f
+	mtctr	r0
+4:	stwu	r4,4(r6)
+	bdnz	4b
+3:	mtctr	r9
+	li	r7,4
+10:	dcbz	r7,r6
+	addi	r6,r6,CACHELINE_BYTES
+	bdnz	10b
+	clrlwi	r5,r8,32-LG_CACHELINE_BYTES
+	addi	r5,r5,4
+2:	srwi	r0,r5,2
+	mtctr	r0
+	bdz	6f
+1:	stwu	r4,4(r6)
+	bdnz	1b
+6:	andi.	r5,r5,3
+7:	cmpwi	0,r5,0
+	beqlr
+	mtctr	r5
+	addi	r6,r6,3
+8:	stbu	r4,1(r6)
+	bdnz	8b
+	blr
+
 _GLOBAL(memset)
 	rlwimi	r4,r4,8,16,23
 	rlwimi	r4,r4,16,0,15
@@ -94,6 +142,85 @@ _GLOBAL(memset)
 	bdnz	8b
 	blr
 
+/*
+ * This version uses dcbz on the complete cache lines in the
+ * destination area to reduce memory traffic.  This requires that
+ * the destination area is cacheable.
+ * We only use this version if the source and dest don't overlap.
+ * -- paulus.
+ */
+_GLOBAL(cacheable_memcpy)
+	add	r7,r3,r5		/* test if the src & dst overlap */
+	add	r8,r4,r5
+	cmplw	0,r4,r7
+	cmplw	1,r3,r8
+	crand	0,0,4			/* cr0.lt &= cr1.lt */
+	blt	memcpy			/* if regions overlap */
+
+	addi	r4,r4,-4
+	addi	r6,r3,-4
+	neg	r0,r3
+	andi.	r0,r0,CACHELINE_MASK	/* # bytes to start of cache line */
+	beq	58f
+
+	cmplw	0,r5,r0			/* is this more than total to do? */
+	blt	63f			/* if not much to do */
+	andi.	r8,r0,3			/* get it word-aligned first */
+	subf	r5,r0,r5
+	mtctr	r8
+	beq+	61f
+70:	lbz	r9,4(r4)		/* do some bytes */
+	stb	r9,4(r6)
+	addi	r4,r4,1
+	addi	r6,r6,1
+	bdnz	70b
+61:	srwi.	r0,r0,2
+	mtctr	r0
+	beq	58f
+72:	lwzu	r9,4(r4)		/* do some words */
+	stwu	r9,4(r6)
+	bdnz	72b
+
+58:	srwi.	r0,r5,LG_CACHELINE_BYTES /* # complete cachelines */
+	clrlwi	r5,r5,32-LG_CACHELINE_BYTES
+	li	r11,4
+	mtctr	r0
+	beq	63f
+53:
+	dcbz	r11,r6
+	COPY_16_BYTES
+#if L1_CACHE_BYTES >= 32
+	COPY_16_BYTES
+#if L1_CACHE_BYTES >= 64
+	COPY_16_BYTES
+	COPY_16_BYTES
+#if L1_CACHE_BYTES >= 128
+	COPY_16_BYTES
+	COPY_16_BYTES
+	COPY_16_BYTES
+	COPY_16_BYTES
+#endif
+#endif
+#endif
+	bdnz	53b
+
+63:	srwi.	r0,r5,2
+	mtctr	r0
+	beq	64f
+30:	lwzu	r0,4(r4)
+	stwu	r0,4(r6)
+	bdnz	30b
+
+64:	andi.	r0,r5,3
+	mtctr	r0
+	beq+	65f
+40:	lbz	r0,4(r4)
+	stb	r0,4(r6)
+	addi	r4,r4,1
+	addi	r6,r6,1
+	bdnz	40b
+65:	blr
+
 _GLOBAL(memmove)
 	cmplw	0,r3,r4
 	bgt	backwards_memcpy
-- 
2.1.0

[PATCH 2/4] powerpc32: swap r4 and r5 in cacheable_memzero

[Christophe Leroy]

We swap r4 and r5, this avoids having to move the len contained in r4
into r5

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index 55f19f9..cbca76c 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -75,18 +75,17 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
  * area is cacheable.  -- paulus
  */
 _GLOBAL(cacheable_memzero)
-	mr	r5,r4
-	li	r4,0
+	li	r5,0
 	addi	r6,r3,-4
-	cmplwi	0,r5,4
+	cmplwi	0,r4,4
 	blt	7f
-	stwu	r4,4(r6)
+	stwu	r5,4(r6)
 	beqlr
 	andi.	r0,r6,3
-	add	r5,r0,r5
+	add	r4,r0,r4
 	subf	r6,r0,r6
 	clrlwi	r7,r6,32-LG_CACHELINE_BYTES
-	add	r8,r7,r5
+	add	r8,r7,r4
 	srwi	r9,r8,LG_CACHELINE_BYTES
 	addic.	r9,r9,-1	/* total number of complete cachelines */
 	ble	2f
@@ -94,26 +93,26 @@ _GLOBAL(cacheable_memzero)
 	srwi.	r0,r0,2
 	beq	3f
 	mtctr	r0
-4:	stwu	r4,4(r6)
+4:	stwu	r5,4(r6)
 	bdnz	4b
 3:	mtctr	r9
 	li	r7,4
 10:	dcbz	r7,r6
 	addi	r6,r6,CACHELINE_BYTES
 	bdnz	10b
-	clrlwi	r5,r8,32-LG_CACHELINE_BYTES
-	addi	r5,r5,4
-2:	srwi	r0,r5,2
+	clrlwi	r4,r8,32-LG_CACHELINE_BYTES
+	addi	r4,r4,4
+2:	srwi	r0,r4,2
 	mtctr	r0
 	bdz	6f
-1:	stwu	r4,4(r6)
+1:	stwu	r5,4(r6)
 	bdnz	1b
-6:	andi.	r5,r5,3
-7:	cmpwi	0,r5,0
+6:	andi.	r4,r4,3
+7:	cmpwi	0,r4,0
 	beqlr
-	mtctr	r5
+	mtctr	r4
 	addi	r6,r6,3
-8:	stbu	r4,1(r6)
+8:	stbu	r5,1(r6)
 	bdnz	8b
 	blr
 
-- 
2.1.0

[PATCH 2/4] powerpc32: swap r4 and r5 in cacheable_memzero

[Christophe Leroy]

We swap r4 and r5, this avoids having to move the len contained in r4
into r5

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index 55f19f9..cbca76c 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -75,18 +75,17 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
  * area is cacheable.  -- paulus
  */
 _GLOBAL(cacheable_memzero)
-	mr	r5,r4
-	li	r4,0
+	li	r5,0
 	addi	r6,r3,-4
-	cmplwi	0,r5,4
+	cmplwi	0,r4,4
 	blt	7f
-	stwu	r4,4(r6)
+	stwu	r5,4(r6)
 	beqlr
 	andi.	r0,r6,3
-	add	r5,r0,r5
+	add	r4,r0,r4
 	subf	r6,r0,r6
 	clrlwi	r7,r6,32-LG_CACHELINE_BYTES
-	add	r8,r7,r5
+	add	r8,r7,r4
 	srwi	r9,r8,LG_CACHELINE_BYTES
 	addic.	r9,r9,-1	/* total number of complete cachelines */
 	ble	2f
@@ -94,26 +93,26 @@ _GLOBAL(cacheable_memzero)
 	srwi.	r0,r0,2
 	beq	3f
 	mtctr	r0
-4:	stwu	r4,4(r6)
+4:	stwu	r5,4(r6)
 	bdnz	4b
 3:	mtctr	r9
 	li	r7,4
 10:	dcbz	r7,r6
 	addi	r6,r6,CACHELINE_BYTES
 	bdnz	10b
-	clrlwi	r5,r8,32-LG_CACHELINE_BYTES
-	addi	r5,r5,4
-2:	srwi	r0,r5,2
+	clrlwi	r4,r8,32-LG_CACHELINE_BYTES
+	addi	r4,r4,4
+2:	srwi	r0,r4,2
 	mtctr	r0
 	bdz	6f
-1:	stwu	r4,4(r6)
+1:	stwu	r5,4(r6)
 	bdnz	1b
-6:	andi.	r5,r5,3
-7:	cmpwi	0,r5,0
+6:	andi.	r4,r4,3
+7:	cmpwi	0,r4,0
 	beqlr
-	mtctr	r5
+	mtctr	r4
 	addi	r6,r6,3
-8:	stbu	r4,1(r6)
+8:	stbu	r5,1(r6)
 	bdnz	8b
 	blr
 
-- 
2.1.0

[PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[Christophe Leroy]

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 and if the buffer is in RAM. If not, it falls back to
generic_memcpy()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index cbca76c..d8a9a86 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -12,6 +12,7 @@
 #include <asm/cache.h>
 #include <asm/errno.h>
 #include <asm/ppc_asm.h>
+#include <asm/page.h>
 
 #define COPY_16_BYTES		\
 	lwz	r7,4(r4);	\
@@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
  * to set them to zero.  This requires that the destination
  * area is cacheable.  -- paulus
  */
+_GLOBAL(memset)
+	cmplwi	r4,0
+	bne-	generic_memset
+	cmplwi	r5,L1_CACHE_BYTES
+	blt-	generic_memset
+	lis	r8,max_pfn@ha
+	lwz	r8,max_pfn@l(r8)
+	tophys	(r9,r3)
+	srwi	r9,r9,PAGE_SHIFT
+	cmplw	r9,r8
+	bge-	generic_memset
+	mr	r4,r5
 _GLOBAL(cacheable_memzero)
 	li	r5,0
 	addi	r6,r3,-4
@@ -116,7 +129,7 @@ _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

[PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[Christophe Leroy]

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 and if the buffer is in RAM. If not, it falls back to
generic_memcpy()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index cbca76c..d8a9a86 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -12,6 +12,7 @@
 #include <asm/cache.h>
 #include <asm/errno.h>
 #include <asm/ppc_asm.h>
+#include <asm/page.h>
 
 #define COPY_16_BYTES		\
 	lwz	r7,4(r4);	\
@@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
  * to set them to zero.  This requires that the destination
  * area is cacheable.  -- paulus
  */
+_GLOBAL(memset)
+	cmplwi	r4,0
+	bne-	generic_memset
+	cmplwi	r5,L1_CACHE_BYTES
+	blt-	generic_memset
+	lis	r8,max_pfn@ha
+	lwz	r8,max_pfn@l(r8)
+	tophys	(r9,r3)
+	srwi	r9,r9,PAGE_SHIFT
+	cmplw	r9,r8
+	bge-	generic_memset
+	mr	r4,r5
 _GLOBAL(cacheable_memzero)
 	li	r5,0
 	addi	r6,r3,-4
@@ -116,7 +129,7 @@ _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

[PATCH 4/4] powerpc32: memcpy: use cacheable_memcpy

[Christophe Leroy]

cacheable_memcpy uses dcbz instruction and is more efficient than
memcpy when the destination is in RAM

This patch renames memcpy as generic_memcpy, and defines memcpy as a
prolog to cacheable_memcpy. This prolog checks if the buffer is
in RAM. If not, it falls back to generic_memcpy()

On MPC885, we get approximatly 7% increase of the transfer rate
on an FTP reception

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index d8a9a86..8f76d49 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -161,13 +161,27 @@ _GLOBAL(generic_memset)
  * We only use this version if the source and dest don't overlap.
  * -- paulus.
  */
+_GLOBAL(memmove)
+	cmplw	0,r3,r4
+	bgt	backwards_memcpy
+	/* fall through */
+
+_GLOBAL(memcpy)
+	cmplwi	r5,L1_CACHE_BYTES
+	blt-	generic_memcpy
+	lis	r8,max_pfn@ha
+	lwz	r8,max_pfn@l(r8)
+	tophys	(r9,r3)
+	srwi	r9,r9,PAGE_SHIFT
+	cmplw	r9,r8
+	bge-	generic_memcpy
 _GLOBAL(cacheable_memcpy)
 	add	r7,r3,r5		/* test if the src & dst overlap */
 	add	r8,r4,r5
 	cmplw	0,r4,r7
 	cmplw	1,r3,r8
 	crand	0,0,4			/* cr0.lt &= cr1.lt */
-	blt	memcpy			/* if regions overlap */
+	blt	generic_memcpy		/* if regions overlap */
 
 	addi	r4,r4,-4
 	addi	r6,r3,-4
@@ -233,12 +247,7 @@ _GLOBAL(cacheable_memcpy)
 	bdnz	40b
 65:	blr
 
-_GLOBAL(memmove)
-	cmplw	0,r3,r4
-	bgt	backwards_memcpy
-	/* fall through */
-
-_GLOBAL(memcpy)
+_GLOBAL(generic_memcpy)
 	srwi.	r7,r5,3
 	addi	r6,r3,-4
 	addi	r4,r4,-4
-- 
2.1.0

[PATCH 4/4] powerpc32: memcpy: use cacheable_memcpy

[Christophe Leroy]

cacheable_memcpy uses dcbz instruction and is more efficient than
memcpy when the destination is in RAM

This patch renames memcpy as generic_memcpy, and defines memcpy as a
prolog to cacheable_memcpy. This prolog checks if the buffer is
in RAM. If not, it falls back to generic_memcpy()

On MPC885, we get approximatly 7% increase of the transfer rate
on an FTP reception

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/lib/copy_32.S | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index d8a9a86..8f76d49 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -161,13 +161,27 @@ _GLOBAL(generic_memset)
  * We only use this version if the source and dest don't overlap.
  * -- paulus.
  */
+_GLOBAL(memmove)
+	cmplw	0,r3,r4
+	bgt	backwards_memcpy
+	/* fall through */
+
+_GLOBAL(memcpy)
+	cmplwi	r5,L1_CACHE_BYTES
+	blt-	generic_memcpy
+	lis	r8,max_pfn@ha
+	lwz	r8,max_pfn@l(r8)
+	tophys	(r9,r3)
+	srwi	r9,r9,PAGE_SHIFT
+	cmplw	r9,r8
+	bge-	generic_memcpy
 _GLOBAL(cacheable_memcpy)
 	add	r7,r3,r5		/* test if the src & dst overlap */
 	add	r8,r4,r5
 	cmplw	0,r4,r7
 	cmplw	1,r3,r8
 	crand	0,0,4			/* cr0.lt &= cr1.lt */
-	blt	memcpy			/* if regions overlap */
+	blt	generic_memcpy		/* if regions overlap */
 
 	addi	r4,r4,-4
 	addi	r6,r3,-4
@@ -233,12 +247,7 @@ _GLOBAL(cacheable_memcpy)
 	bdnz	40b
 65:	blr
 
-_GLOBAL(memmove)
-	cmplw	0,r3,r4
-	bgt	backwards_memcpy
-	/* fall through */
-
-_GLOBAL(memcpy)
+_GLOBAL(generic_memcpy)
 	srwi.	r7,r5,3
 	addi	r6,r3,-4
 	addi	r4,r4,-4
-- 
2.1.0

Re: [PATCH 1/4] Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero functions"

[Scott Wood]

On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
> This partially reverts
> commit 'powerpc: Remove duplicate cacheable_memcpy/memzero functions
> ("f909a35bdfb7cb350d078a2cf888162eeb20381c")'

I don't have that SHA.  Do you mean
b05ae4ee602b7dc90771408ccf0972e1b3801a35?

> Functions cacheable_memcpy/memzero are more efficient than
> memcpy/memset as they use the dcbz instruction which avoids refill
> of the cacheline with the data that we will overwrite.

I don't see anything in this patchset that addresses the "NOTE: The old
routines are just flat buggy on kernels that support hardware with
different cacheline sizes" comment.

-Scott

Re: [PATCH 1/4] Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero functions"

[Scott Wood]

On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
> This partially reverts
> commit 'powerpc: Remove duplicate cacheable_memcpy/memzero functions
> ("f909a35bdfb7cb350d078a2cf888162eeb20381c")'

I don't have that SHA.  Do you mean
b05ae4ee602b7dc90771408ccf0972e1b3801a35?

> Functions cacheable_memcpy/memzero are more efficient than
> memcpy/memset as they use the dcbz instruction which avoids refill
> of the cacheline with the data that we will overwrite.

I don't see anything in this patchset that addresses the "NOTE: The old
routines are just flat buggy on kernels that support hardware with
different cacheline sizes" comment.

-Scott

Re: [PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[Scott Wood]

On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
> 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 and if the buffer is in RAM. If not, it falls back to
> generic_memcpy()
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
>  arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> index cbca76c..d8a9a86 100644
> --- a/arch/powerpc/lib/copy_32.S
> +++ b/arch/powerpc/lib/copy_32.S
> @@ -12,6 +12,7 @@
>  #include <asm/cache.h>
>  #include <asm/errno.h>
>  #include <asm/ppc_asm.h>
> +#include <asm/page.h>
>  
>  #define COPY_16_BYTES		\
>  	lwz	r7,4(r4);	\
> @@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
>   * to set them to zero.  This requires that the destination
>   * area is cacheable.  -- paulus
>   */
> +_GLOBAL(memset)
> +	cmplwi	r4,0
> +	bne-	generic_memset
> +	cmplwi	r5,L1_CACHE_BYTES
> +	blt-	generic_memset
> +	lis	r8,max_pfn@ha
> +	lwz	r8,max_pfn@l(r8)
> +	tophys	(r9,r3)
> +	srwi	r9,r9,PAGE_SHIFT
> +	cmplw	r9,r8
> +	bge-	generic_memset
> +	mr	r4,r5

max_pfn includes highmem, and tophys only works on normal kernel
addresses.

If we were to point memset_io, memcpy_toio, etc. at noncacheable
versions, are there any other callers left that can reasonably point at
uncacheable memory?

-Scott

Re: [PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[Scott Wood]

On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
> 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 and if the buffer is in RAM. If not, it falls back to
> generic_memcpy()
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
>  arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> index cbca76c..d8a9a86 100644
> --- a/arch/powerpc/lib/copy_32.S
> +++ b/arch/powerpc/lib/copy_32.S
> @@ -12,6 +12,7 @@
>  #include <asm/cache.h>
>  #include <asm/errno.h>
>  #include <asm/ppc_asm.h>
> +#include <asm/page.h>
>  
>  #define COPY_16_BYTES		\
>  	lwz	r7,4(r4);	\
> @@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
>   * to set them to zero.  This requires that the destination
>   * area is cacheable.  -- paulus
>   */
> +_GLOBAL(memset)
> +	cmplwi	r4,0
> +	bne-	generic_memset
> +	cmplwi	r5,L1_CACHE_BYTES
> +	blt-	generic_memset
> +	lis	r8,max_pfn@ha
> +	lwz	r8,max_pfn@l(r8)
> +	tophys	(r9,r3)
> +	srwi	r9,r9,PAGE_SHIFT
> +	cmplw	r9,r8
> +	bge-	generic_memset
> +	mr	r4,r5

max_pfn includes highmem, and tophys only works on normal kernel
addresses.

If we were to point memset_io, memcpy_toio, etc. at noncacheable
versions, are there any other callers left that can reasonably point at
uncacheable memory?

-Scott

Re: [PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[christophe leroy]

Le 14/05/2015 02:55, Scott Wood a écrit :
> On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
>> 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 and if the buffer is in RAM. If not, it falls back to
>> generic_memcpy()
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>>   arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
>> index cbca76c..d8a9a86 100644
>> --- a/arch/powerpc/lib/copy_32.S
>> +++ b/arch/powerpc/lib/copy_32.S
>> @@ -12,6 +12,7 @@
>>   #include <asm/cache.h>
>>   #include <asm/errno.h>
>>   #include <asm/ppc_asm.h>
>> +#include <asm/page.h>
>>   
>>   #define COPY_16_BYTES		\
>>   	lwz	r7,4(r4);	\
>> @@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
>>    * to set them to zero.  This requires that the destination
>>    * area is cacheable.  -- paulus
>>    */
>> +_GLOBAL(memset)
>> +	cmplwi	r4,0
>> +	bne-	generic_memset
>> +	cmplwi	r5,L1_CACHE_BYTES
>> +	blt-	generic_memset
>> +	lis	r8,max_pfn@ha
>> +	lwz	r8,max_pfn@l(r8)
>> +	tophys	(r9,r3)
>> +	srwi	r9,r9,PAGE_SHIFT
>> +	cmplw	r9,r8
>> +	bge-	generic_memset
>> +	mr	r4,r5
> max_pfn includes highmem, and tophys only works on normal kernel
> addresses.
Is there any other simple way to determine whether an address is in RAM 
or not ?

I did that because of the below function from mm/mem.c

|int  page_is_ram(unsigned long  pfn)
{
#ifndef CONFIG_PPC64	/* XXX for now */
	return  pfn<  max_pfn;
#else
	unsigned long  paddr= (pfn<<  PAGE_SHIFT);
	struct  memblock_region*reg;

	for_each_memblock(memory,  reg)
		if  (paddr>=  reg->base&&  paddr< (reg->base+  reg->size))
			return  1;
	return  0;
#endif
}
|



>
> If we were to point memset_io, memcpy_toio, etc. at noncacheable
> versions, are there any other callers left that can reasonably point at
> uncacheable memory?
Do you mean we could just consider that memcpy() and memset() are called 
only with destination on RAM and thus we could avoid the check ?
copy_tofrom_user() already does this assumption (allthought a user app 
could possibly provide a buffer located in an ALSA mapped IO area)

Christophe


---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
http://www.avast.com

Re: [PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[christophe leroy]

Le 14/05/2015 02:55, Scott Wood a écrit :
> On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
>> 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 and if the buffer is in RAM. If not, it falls back to
>> generic_memcpy()
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
>> ---
>>   arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
>> index cbca76c..d8a9a86 100644
>> --- a/arch/powerpc/lib/copy_32.S
>> +++ b/arch/powerpc/lib/copy_32.S
>> @@ -12,6 +12,7 @@
>>   #include <asm/cache.h>
>>   #include <asm/errno.h>
>>   #include <asm/ppc_asm.h>
>> +#include <asm/page.h>
>>   
>>   #define COPY_16_BYTES		\
>>   	lwz	r7,4(r4);	\
>> @@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
>>    * to set them to zero.  This requires that the destination
>>    * area is cacheable.  -- paulus
>>    */
>> +_GLOBAL(memset)
>> +	cmplwi	r4,0
>> +	bne-	generic_memset
>> +	cmplwi	r5,L1_CACHE_BYTES
>> +	blt-	generic_memset
>> +	lis	r8,max_pfn@ha
>> +	lwz	r8,max_pfn@l(r8)
>> +	tophys	(r9,r3)
>> +	srwi	r9,r9,PAGE_SHIFT
>> +	cmplw	r9,r8
>> +	bge-	generic_memset
>> +	mr	r4,r5
> max_pfn includes highmem, and tophys only works on normal kernel
> addresses.
Is there any other simple way to determine whether an address is in RAM 
or not ?

I did that because of the below function from mm/mem.c

|int  page_is_ram(unsigned long  pfn)
{
#ifndef CONFIG_PPC64	/* XXX for now */
	return  pfn<  max_pfn;
#else
	unsigned long  paddr= (pfn<<  PAGE_SHIFT);
	struct  memblock_region*reg;

	for_each_memblock(memory,  reg)
		if  (paddr>=  reg->base&&  paddr< (reg->base+  reg->size))
			return  1;
	return  0;
#endif
}
|



>
> If we were to point memset_io, memcpy_toio, etc. at noncacheable
> versions, are there any other callers left that can reasonably point at
> uncacheable memory?
Do you mean we could just consider that memcpy() and memset() are called 
only with destination on RAM and thus we could avoid the check ?
copy_tofrom_user() already does this assumption (allthought a user app 
could possibly provide a buffer located in an ALSA mapped IO area)

Christophe


---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
http://www.avast.com

Re: [PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[Scott Wood]

On Thu, 2015-05-14 at 10:50 +0200, christophe leroy wrote:
> 
> Le 14/05/2015 02:55, Scott Wood a écrit :
> > On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
> >> 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 and if the buffer is in RAM. If not, it falls back to
> >> generic_memcpy()
> >>
> >> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> >> ---
> >>   arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
> >>   1 file changed, 14 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> >> index cbca76c..d8a9a86 100644
> >> --- a/arch/powerpc/lib/copy_32.S
> >> +++ b/arch/powerpc/lib/copy_32.S
> >> @@ -12,6 +12,7 @@
> >>   #include <asm/cache.h>
> >>   #include <asm/errno.h>
> >>   #include <asm/ppc_asm.h>
> >> +#include <asm/page.h>
> >>   
> >>   #define COPY_16_BYTES		\
> >>   	lwz	r7,4(r4);	\
> >> @@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
> >>    * to set them to zero.  This requires that the destination
> >>    * area is cacheable.  -- paulus
> >>    */
> >> +_GLOBAL(memset)
> >> +	cmplwi	r4,0
> >> +	bne-	generic_memset
> >> +	cmplwi	r5,L1_CACHE_BYTES
> >> +	blt-	generic_memset
> >> +	lis	r8,max_pfn@ha
> >> +	lwz	r8,max_pfn@l(r8)
> >> +	tophys	(r9,r3)
> >> +	srwi	r9,r9,PAGE_SHIFT
> >> +	cmplw	r9,r8
> >> +	bge-	generic_memset
> >> +	mr	r4,r5
> > max_pfn includes highmem, and tophys only works on normal kernel
> > addresses.
> Is there any other simple way to determine whether an address is in RAM 
> or not ?

If you want to do it based on the virtual address, rather than doing a
tablewalk or TLB search, you need to limit it to lowmem.

> I did that because of the below function from mm/mem.c
> 
> |int  page_is_ram(unsigned long  pfn)
> {
> #ifndef CONFIG_PPC64	/* XXX for now */
> 	return  pfn<  max_pfn;
> #else
> 	unsigned long  paddr= (pfn<<  PAGE_SHIFT);
> 	struct  memblock_region*reg;
> 
> 	for_each_memblock(memory,  reg)
> 		if  (paddr>=  reg->base&&  paddr< (reg->base+  reg->size))
> 			return  1;
> 	return  0;
> #endif
> }

Right, the problem is figuring out the pfn in the first place.

> > If we were to point memset_io, memcpy_toio, etc. at noncacheable
> > versions, are there any other callers left that can reasonably point at
> > uncacheable memory?
> Do you mean we could just consider that memcpy() and memset() are called 
> only with destination on RAM and thus we could avoid the check ?

Maybe.  If that's not a safe assumption I hope someone will point it
out.

> copy_tofrom_user() already does this assumption (allthought a user app 
> could possibly provide a buffer located in an ALSA mapped IO area)

The user could also pass in NULL.  That's what the fixups are for. :-)

-Scott

Re: [PATCH 3/4] powerpc32: memset(0): use cacheable_memzero

[Scott Wood]

On Thu, 2015-05-14 at 10:50 +0200, christophe leroy wrote:
> 
> Le 14/05/2015 02:55, Scott Wood a écrit :
> > On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
> >> 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 and if the buffer is in RAM. If not, it falls back to
> >> generic_memcpy()
> >>
> >> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> >> ---
> >>   arch/powerpc/lib/copy_32.S | 15 ++++++++++++++-
> >>   1 file changed, 14 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> >> index cbca76c..d8a9a86 100644
> >> --- a/arch/powerpc/lib/copy_32.S
> >> +++ b/arch/powerpc/lib/copy_32.S
> >> @@ -12,6 +12,7 @@
> >>   #include <asm/cache.h>
> >>   #include <asm/errno.h>
> >>   #include <asm/ppc_asm.h>
> >> +#include <asm/page.h>
> >>   
> >>   #define COPY_16_BYTES		\
> >>   	lwz	r7,4(r4);	\
> >> @@ -74,6 +75,18 @@ CACHELINE_MASK = (L1_CACHE_BYTES-1)
> >>    * to set them to zero.  This requires that the destination
> >>    * area is cacheable.  -- paulus
> >>    */
> >> +_GLOBAL(memset)
> >> +	cmplwi	r4,0
> >> +	bne-	generic_memset
> >> +	cmplwi	r5,L1_CACHE_BYTES
> >> +	blt-	generic_memset
> >> +	lis	r8,max_pfn@ha
> >> +	lwz	r8,max_pfn@l(r8)
> >> +	tophys	(r9,r3)
> >> +	srwi	r9,r9,PAGE_SHIFT
> >> +	cmplw	r9,r8
> >> +	bge-	generic_memset
> >> +	mr	r4,r5
> > max_pfn includes highmem, and tophys only works on normal kernel
> > addresses.
> Is there any other simple way to determine whether an address is in RAM 
> or not ?

If you want to do it based on the virtual address, rather than doing a
tablewalk or TLB search, you need to limit it to lowmem.

> I did that because of the below function from mm/mem.c
> 
> |int  page_is_ram(unsigned long  pfn)
> {
> #ifndef CONFIG_PPC64	/* XXX for now */
> 	return  pfn<  max_pfn;
> #else
> 	unsigned long  paddr= (pfn<<  PAGE_SHIFT);
> 	struct  memblock_region*reg;
> 
> 	for_each_memblock(memory,  reg)
> 		if  (paddr>=  reg->base&&  paddr< (reg->base+  reg->size))
> 			return  1;
> 	return  0;
> #endif
> }

Right, the problem is figuring out the pfn in the first place.

> > If we were to point memset_io, memcpy_toio, etc. at noncacheable
> > versions, are there any other callers left that can reasonably point at
> > uncacheable memory?
> Do you mean we could just consider that memcpy() and memset() are called 
> only with destination on RAM and thus we could avoid the check ?

Maybe.  If that's not a safe assumption I hope someone will point it
out.

> copy_tofrom_user() already does this assumption (allthought a user app 
> could possibly provide a buffer located in an ALSA mapped IO area)

The user could also pass in NULL.  That's what the fixups are for. :-)

-Scott

Re: [PATCH 1/4] Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero functions"

[christophe leroy]

Le 14/05/2015 02:49, Scott Wood a écrit :
> On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
>> This partially reverts
>> commit 'powerpc: Remove duplicate cacheable_memcpy/memzero functions
>> ("f909a35bdfb7cb350d078a2cf888162eeb20381c")'
> I don't have that SHA.  Do you mean
> b05ae4ee602b7dc90771408ccf0972e1b3801a35?
Right, took it from the wrong tree sorry.
>
>> Functions cacheable_memcpy/memzero are more efficient than
>> memcpy/memset as they use the dcbz instruction which avoids refill
>> of the cacheline with the data that we will overwrite.
> I don't see anything in this patchset that addresses the "NOTE: The old
> routines are just flat buggy on kernels that support hardware with
> different cacheline sizes" comment.
I believe the NOTE means that if a kernel is compiled for several CPUs 
having different cache line size,
then it will not work. But it is also the case of other functions using 
dcbz instruction, like copy_page() clear_page() copy_tofrom_user().

And indeed, this seems only possible in three cases:
1/ With CONFIG_44x as 47x has different size than 44x and 46x. However 
it is explicitly stated in arch/powerpc/platforms/44x/Kconfig : "config 
PPC_47x This option enables support for the 47x family of processors and 
is not currently compatible with other 44x or 46x varients"
2/ With CONFIG_PPC_85xx, as PPC_E500MC has different size than other 
E500. However it is explicitly stated in 
arch/powerpc/platforms/Kconfig.cputype : "config PPC_E500MC This must be 
enabled for running on e500mc (and derivatives such as e5500/e6500), and 
must be disabled for running on e500v1 or e500v2."
3/ With CONFIG_403GCX as 403GCX has different size than other 40x. 
However it seems to be no way to select CONFIG_403GCX from 
arch/powerpc/platforms/40x/Kconfig

Christophe

---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
http://www.avast.com

Re: [PATCH 1/4] Partially revert "powerpc: Remove duplicate cacheable_memcpy/memzero functions"

[christophe leroy]

Le 14/05/2015 02:49, Scott Wood a écrit :
> On Tue, 2015-05-12 at 15:32 +0200, Christophe Leroy wrote:
>> This partially reverts
>> commit 'powerpc: Remove duplicate cacheable_memcpy/memzero functions
>> ("f909a35bdfb7cb350d078a2cf888162eeb20381c")'
> I don't have that SHA.  Do you mean
> b05ae4ee602b7dc90771408ccf0972e1b3801a35?
Right, took it from the wrong tree sorry.
>
>> Functions cacheable_memcpy/memzero are more efficient than
>> memcpy/memset as they use the dcbz instruction which avoids refill
>> of the cacheline with the data that we will overwrite.
> I don't see anything in this patchset that addresses the "NOTE: The old
> routines are just flat buggy on kernels that support hardware with
> different cacheline sizes" comment.
I believe the NOTE means that if a kernel is compiled for several CPUs 
having different cache line size,
then it will not work. But it is also the case of other functions using 
dcbz instruction, like copy_page() clear_page() copy_tofrom_user().

And indeed, this seems only possible in three cases:
1/ With CONFIG_44x as 47x has different size than 44x and 46x. However 
it is explicitly stated in arch/powerpc/platforms/44x/Kconfig : "config 
PPC_47x This option enables support for the 47x family of processors and 
is not currently compatible with other 44x or 46x varients"
2/ With CONFIG_PPC_85xx, as PPC_E500MC has different size than other 
E500. However it is explicitly stated in 
arch/powerpc/platforms/Kconfig.cputype : "config PPC_E500MC This must be 
enabled for running on e500mc (and derivatives such as e5500/e6500), and 
must be disabled for running on e500v1 or e500v2."
3/ With CONFIG_403GCX as 403GCX has different size than other 40x. 
However it seems to be no way to select CONFIG_403GCX from 
arch/powerpc/platforms/40x/Kconfig

Christophe

---
L'absence de virus dans ce courrier électronique a été vérifiée par le logiciel antivirus Avast.
http://www.avast.com