* [PATCH 1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp
@ 2016-05-25 22:38 Anton Blanchard
2016-05-25 22:39 ` [PATCH 2/2] powerpc: Align hot loops of some string functions Anton Blanchard
2016-06-15 12:39 ` [1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp Michael Ellerman
0 siblings, 2 replies; 8+ messages in thread
From: Anton Blanchard @ 2016-05-25 22:38 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Michael Ellerman, Paul Mackerras, acsawdey
Cc: linuxppc-dev
A number of our assembly implementations of string functions do not
align their hot loops. I was going to align them manually, but I
realised that they are are almost instruction for instruction
identical to what gcc produces, with the advantage that gcc does
align them.
In light of that, let's just remove the assembly versions.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
index e40010a..da3cdff 100644
Index: linux.junk/arch/powerpc/include/asm/string.h
===================================================================
--- linux.junk.orig/arch/powerpc/include/asm/string.h
+++ linux.junk/arch/powerpc/include/asm/string.h
@@ -3,12 +3,8 @@
#ifdef __KERNEL__
-#define __HAVE_ARCH_STRCPY
#define __HAVE_ARCH_STRNCPY
-#define __HAVE_ARCH_STRLEN
-#define __HAVE_ARCH_STRCMP
#define __HAVE_ARCH_STRNCMP
-#define __HAVE_ARCH_STRCAT
#define __HAVE_ARCH_MEMSET
#define __HAVE_ARCH_MEMCPY
#define __HAVE_ARCH_MEMMOVE
Index: linux.junk/arch/powerpc/lib/ppc_ksyms.c
===================================================================
--- linux.junk.orig/arch/powerpc/lib/ppc_ksyms.c
+++ linux.junk/arch/powerpc/lib/ppc_ksyms.c
@@ -9,11 +9,7 @@ EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(memcmp);
EXPORT_SYMBOL(memchr);
-EXPORT_SYMBOL(strcpy);
EXPORT_SYMBOL(strncpy);
-EXPORT_SYMBOL(strcat);
-EXPORT_SYMBOL(strlen);
-EXPORT_SYMBOL(strcmp);
EXPORT_SYMBOL(strncmp);
#ifndef CONFIG_GENERIC_CSUM
Index: linux.junk/arch/powerpc/lib/string.S
===================================================================
--- linux.junk.orig/arch/powerpc/lib/string.S
+++ linux.junk/arch/powerpc/lib/string.S
@@ -16,15 +16,6 @@
PPC_LONG_ALIGN
.text
-_GLOBAL(strcpy)
- addi r5,r3,-1
- addi r4,r4,-1
-1: lbzu r0,1(r4)
- cmpwi 0,r0,0
- stbu r0,1(r5)
- bne 1b
- blr
-
/* This clears out any unused part of the destination buffer,
just as the libc version does. -- paulus */
_GLOBAL(strncpy)
@@ -45,30 +36,6 @@ _GLOBAL(strncpy)
bdnz 2b
blr
-_GLOBAL(strcat)
- addi r5,r3,-1
- addi r4,r4,-1
-1: lbzu r0,1(r5)
- cmpwi 0,r0,0
- bne 1b
- addi r5,r5,-1
-1: lbzu r0,1(r4)
- cmpwi 0,r0,0
- stbu r0,1(r5)
- bne 1b
- blr
-
-_GLOBAL(strcmp)
- addi r5,r3,-1
- addi r4,r4,-1
-1: lbzu r3,1(r5)
- cmpwi 1,r3,0
- lbzu r0,1(r4)
- subf. r3,r0,r3
- beqlr 1
- beq 1b
- blr
-
_GLOBAL(strncmp)
PPC_LCMPI 0,r5,0
beq- 2f
@@ -85,14 +52,6 @@ _GLOBAL(strncmp)
2: li r3,0
blr
-_GLOBAL(strlen)
- addi r4,r3,-1
-1: lbzu r0,1(r4)
- cmpwi 0,r0,0
- bne 1b
- subf r3,r3,r4
- blr
-
#ifdef CONFIG_PPC32
_GLOBAL(memcmp)
PPC_LCMPI 0,r5,0
^ permalink raw reply [flat|nested] 8+ messages in thread* [PATCH 2/2] powerpc: Align hot loops of some string functions
2016-05-25 22:38 [PATCH 1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp Anton Blanchard
@ 2016-05-25 22:39 ` Anton Blanchard
2016-05-26 7:24 ` Christophe Leroy
2016-06-15 12:39 ` [2/2] " Michael Ellerman
2016-06-15 12:39 ` [1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp Michael Ellerman
1 sibling, 2 replies; 8+ messages in thread
From: Anton Blanchard @ 2016-05-25 22:39 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Michael Ellerman, Paul Mackerras, acsawdey
Cc: linuxppc-dev
Align the hot loops in our assembly implementation of strncpy(),
strncmp() and memchr().
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: linux.junk/arch/powerpc/lib/string.S
===================================================================
--- linux.junk.orig/arch/powerpc/lib/string.S
+++ linux.junk/arch/powerpc/lib/string.S
@@ -24,6 +24,7 @@ _GLOBAL(strncpy)
mtctr r5
addi r6,r3,-1
addi r4,r4,-1
+ .balign 16
1: lbzu r0,1(r4)
cmpwi 0,r0,0
stbu r0,1(r6)
@@ -42,6 +43,7 @@ _GLOBAL(strncmp)
mtctr r5
addi r5,r3,-1
addi r4,r4,-1
+ .balign 16
1: lbzu r3,1(r5)
cmpwi 1,r3,0
lbzu r0,1(r4)
@@ -73,6 +75,7 @@ _GLOBAL(memchr)
beq- 2f
mtctr r5
addi r3,r3,-1
+ .balign 16
1: lbzu r0,1(r3)
cmpw 0,r0,r4
bdnzf 2,1b
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Align hot loops of some string functions
2016-05-25 22:39 ` [PATCH 2/2] powerpc: Align hot loops of some string functions Anton Blanchard
@ 2016-05-26 7:24 ` Christophe Leroy
2016-05-26 19:37 ` Segher Boessenkool
2016-06-15 12:39 ` [2/2] " Michael Ellerman
1 sibling, 1 reply; 8+ messages in thread
From: Christophe Leroy @ 2016-05-26 7:24 UTC (permalink / raw)
To: Anton Blanchard, Benjamin Herrenschmidt, Michael Ellerman,
Paul Mackerras, acsawdey
Cc: linuxppc-dev
Le 26/05/2016 à 00:39, Anton Blanchard via Linuxppc-dev a écrit :
> Align the hot loops in our assembly implementation of strncpy(),
> strncmp() and memchr().
Wouldn't it be better to add nops before the function entry in order to
get the hot loop aligned, instead of adding nops in the middle of the
function ?
Christophe
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
> ---
>
> Index: linux.junk/arch/powerpc/lib/string.S
> ===================================================================
> --- linux.junk.orig/arch/powerpc/lib/string.S
> +++ linux.junk/arch/powerpc/lib/string.S
> @@ -24,6 +24,7 @@ _GLOBAL(strncpy)
> mtctr r5
> addi r6,r3,-1
> addi r4,r4,-1
> + .balign 16
> 1: lbzu r0,1(r4)
> cmpwi 0,r0,0
> stbu r0,1(r6)
> @@ -42,6 +43,7 @@ _GLOBAL(strncmp)
> mtctr r5
> addi r5,r3,-1
> addi r4,r4,-1
> + .balign 16
> 1: lbzu r3,1(r5)
> cmpwi 1,r3,0
> lbzu r0,1(r4)
> @@ -73,6 +75,7 @@ _GLOBAL(memchr)
> beq- 2f
> mtctr r5
> addi r3,r3,-1
> + .balign 16
> 1: lbzu r0,1(r3)
> cmpw 0,r0,r4
> bdnzf 2,1b
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Align hot loops of some string functions
2016-05-26 7:24 ` Christophe Leroy
@ 2016-05-26 19:37 ` Segher Boessenkool
2016-05-27 5:45 ` Christophe Leroy
0 siblings, 1 reply; 8+ messages in thread
From: Segher Boessenkool @ 2016-05-26 19:37 UTC (permalink / raw)
To: Christophe Leroy
Cc: Anton Blanchard, Benjamin Herrenschmidt, Michael Ellerman,
Paul Mackerras, acsawdey, linuxppc-dev
On Thu, May 26, 2016 at 09:24:51AM +0200, Christophe Leroy wrote:
> Wouldn't it be better to add nops before the function entry in order to
> get the hot loop aligned, instead of adding nops in the middle of the
> function ?
Why would that be better? The nops are executed once per function call
in either case, there are the same number of nops in either case, and
on most CPUs nops aren't actually executed anyway (they are decoded and
the thrown away).
Segher
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Align hot loops of some string functions
2016-05-26 19:37 ` Segher Boessenkool
@ 2016-05-27 5:45 ` Christophe Leroy
2016-05-27 6:26 ` Segher Boessenkool
0 siblings, 1 reply; 8+ messages in thread
From: Christophe Leroy @ 2016-05-27 5:45 UTC (permalink / raw)
To: Segher Boessenkool
Cc: Anton Blanchard, Benjamin Herrenschmidt, Michael Ellerman,
Paul Mackerras, acsawdey, linuxppc-dev
Le 26/05/2016 à 21:37, Segher Boessenkool a écrit :
> On Thu, May 26, 2016 at 09:24:51AM +0200, Christophe Leroy wrote:
>> Wouldn't it be better to add nops before the function entry in order to
>> get the hot loop aligned, instead of adding nops in the middle of the
>> function ?
> Why would that be better? The nops are executed once per function call
> in either case, there are the same number of nops in either case, and
> on most CPUs nops aren't actually executed anyway (they are decoded and
> the thrown away).
>
The idea was to not execute them:
|.balign 16 nop nop _GLOBAL(strcpy) addi r5,r3,-1 addi r4,r4,-1 1: lbzu
r0,1(r4) cmpwi 0,r0,0 stbu r0,1(r5) bne 1b blr |
Christophe
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH 2/2] powerpc: Align hot loops of some string functions
2016-05-27 5:45 ` Christophe Leroy
@ 2016-05-27 6:26 ` Segher Boessenkool
0 siblings, 0 replies; 8+ messages in thread
From: Segher Boessenkool @ 2016-05-27 6:26 UTC (permalink / raw)
To: Christophe Leroy
Cc: Anton Blanchard, Benjamin Herrenschmidt, Michael Ellerman,
Paul Mackerras, acsawdey, linuxppc-dev
On Fri, May 27, 2016 at 07:45:18AM +0200, Christophe Leroy wrote:
> >>Wouldn't it be better to add nops before the function entry in order to
> >>get the hot loop aligned, instead of adding nops in the middle of the
> >>function ?
> >Why would that be better? The nops are executed once per function call
> >in either case, there are the same number of nops in either case, and
> >on most CPUs nops aren't actually executed anyway (they are decoded and
> >the thrown away).
> >
> The idea was to not execute them:
>
> |.balign 16 nop nop _GLOBAL(strcpy) addi r5,r3,-1 addi r4,r4,-1 1:
> lbzu r0,1(r4) cmpwi 0,r0,0 stbu r0,1(r5) bne 1b blr |
That performs _worse_ on most modern CPUs (the first decode will decode
less, so instructions are available for execution later). That's why
functions are aligned in the first place!
Segher
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [2/2] powerpc: Align hot loops of some string functions
2016-05-25 22:39 ` [PATCH 2/2] powerpc: Align hot loops of some string functions Anton Blanchard
2016-05-26 7:24 ` Christophe Leroy
@ 2016-06-15 12:39 ` Michael Ellerman
1 sibling, 0 replies; 8+ messages in thread
From: Michael Ellerman @ 2016-06-15 12:39 UTC (permalink / raw)
To: Unknown sender due to SPF, Benjamin Herrenschmidt,
Paul Mackerras, acsawdey
Cc: linuxppc-dev
On Wed, 2016-25-05 at 22:39:55 UTC, Unknown sender due to SPF wrote:
> Align the hot loops in our assembly implementation of strncpy(),
> strncmp() and memchr().
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/87a156fb18fe15d012c3db506b
cheers
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp
2016-05-25 22:38 [PATCH 1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp Anton Blanchard
2016-05-25 22:39 ` [PATCH 2/2] powerpc: Align hot loops of some string functions Anton Blanchard
@ 2016-06-15 12:39 ` Michael Ellerman
1 sibling, 0 replies; 8+ messages in thread
From: Michael Ellerman @ 2016-06-15 12:39 UTC (permalink / raw)
To: Unknown sender due to SPF, Benjamin Herrenschmidt,
Paul Mackerras, acsawdey
Cc: linuxppc-dev
On Wed, 2016-25-05 at 22:38:13 UTC, Unknown sender due to SPF wrote:
> A number of our assembly implementations of string functions do not
> align their hot loops. I was going to align them manually, but I
> realised that they are are almost instruction for instruction
> identical to what gcc produces, with the advantage that gcc does
> align them.
>
> In light of that, let's just remove the assembly versions.
>
> Signed-off-by: Anton Blanchard <anton@samba.org>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/3ece16632b64120df2ef566ce3
cheers
^ permalink raw reply [flat|nested] 8+ messages in thread
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2016-05-25 22:38 [PATCH 1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp Anton Blanchard
2016-05-25 22:39 ` [PATCH 2/2] powerpc: Align hot loops of some string functions Anton Blanchard
2016-05-26 7:24 ` Christophe Leroy
2016-05-26 19:37 ` Segher Boessenkool
2016-05-27 5:45 ` Christophe Leroy
2016-05-27 6:26 ` Segher Boessenkool
2016-06-15 12:39 ` [2/2] " Michael Ellerman
2016-06-15 12:39 ` [1/2] powerpc: Remove assembly versions of strcpy, strcat, strlen and strcmp Michael Ellerman
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