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[PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls

Started byVijay Kumar <vijay.ac.kumar@oracle.com>
First post2017-09-27 21:30 +0200
Last post2017-09-28 00:20 +0200
Articles 6 — 4 participants

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  [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls Vijay Kumar <vijay.ac.kumar@oracle.com> - 2017-09-27 21:30 +0200
    Re: [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls Sam Ravnborg <sam@ravnborg.org> - 2017-09-27 22:00 +0200
      Re: [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls Vijay Kumar <vijay.ac.kumar@oracle.com> - 2017-09-27 22:30 +0200
      Re: [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls David Miller <davem@davemloft.net> - 2017-09-27 23:10 +0200
      Re: [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls Anthony Yznaga <anthony.yznaga@oracle.com> - 2017-09-27 23:50 +0200
        Re: [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls David Miller <davem@davemloft.net> - 2017-09-28 00:20 +0200

#1740960 — [PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls

FromVijay Kumar <vijay.ac.kumar@oracle.com>
Date2017-09-27 21:30 +0200
Subject[PATCH v2 2/2] sparc64: Use lzcnt instruction for fls and __fls
Message-ID<uuqbU-7c0-15@gated-at.bofh.it>
For T4 and above, patch fls and __fls functions
at the boot time to use lzcnt instruction.

Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Reviewed-by: Babu Moger <babu.moger@oracle.com>
---
 arch/sparc/Makefile         |    1 +
 arch/sparc/kernel/head_64.S |    2 ++
 arch/sparc/lib/Makefile     |    3 +++
 arch/sparc/lib/NG4fls.S     |   30 ++++++++++++++++++++++++++++++
 arch/sparc/lib/NG4patch.S   |    9 +++++++++
 5 files changed, 45 insertions(+), 0 deletions(-)

diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
index 8496a07..0763cd8 100644
--- a/arch/sparc/Makefile
+++ b/arch/sparc/Makefile
@@ -48,6 +48,7 @@ KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
 KBUILD_CFLAGS += -Wa,--undeclared-regs
 KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
 KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
+KBUILD_AFLAGS += -Wa,-Asparc4
 
 ifeq ($(CONFIG_MCOUNT),y)
   KBUILD_CFLAGS += -pg
diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
index 78e0211..1165254 100644
--- a/arch/sparc/kernel/head_64.S
+++ b/arch/sparc/kernel/head_64.S
@@ -628,6 +628,8 @@ niagara4_patch:
 	 nop
 	call	niagara4_patch_pageops
 	 nop
+	call	niagara4_patch_fls
+	 nop
 
 	ba,a,pt	%xcc, 80f
 	 nop
diff --git a/arch/sparc/lib/Makefile b/arch/sparc/lib/Makefile
index eefbb9c..72d2d8c 100644
--- a/arch/sparc/lib/Makefile
+++ b/arch/sparc/lib/Makefile
@@ -46,3 +46,6 @@ lib-$(CONFIG_SPARC64) += mcount.o ipcsum.o xor.o hweight.o ffs.o
 obj-$(CONFIG_SPARC64) += iomap.o
 obj-$(CONFIG_SPARC32) += atomic32.o ucmpdi2.o
 obj-$(CONFIG_SPARC64) += PeeCeeI.o
+
+obj-$(CONFIG_SPARC64) += fls.o
+obj-$(CONFIG_SPARC64) += NG4fls.o
diff --git a/arch/sparc/lib/NG4fls.S b/arch/sparc/lib/NG4fls.S
new file mode 100644
index 0000000..eb239aa
--- /dev/null
+++ b/arch/sparc/lib/NG4fls.S
@@ -0,0 +1,30 @@
+/* NG4fls.S: SPARC optimized fls and __fls for T4 and above.
+ *
+ * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ */
+
+	.text
+	.align 32
+
+	.globl NG4fls
+	.globl __NG4fls
+	.type  NG4fls, #function
+	.type  __NG4fls, #function
+
+NG4fls:
+	lzcnt   %o0, %o1
+	mov     64, %o2
+	retl
+	 sub     %o2, %o1, %o0
+	.size   NG4fls, .-NG4fls
+
+__NG4fls:
+	brz,pn  %o0, 1f
+        mov	%o0, %o1
+	lzcnt	%o1, %o0
+	mov     63, %o2
+	sub     %o2, %o0, %o0
+1:
+	retl
+	 nop
+	.size   __NG4fls, .-__NG4fls
diff --git a/arch/sparc/lib/NG4patch.S b/arch/sparc/lib/NG4patch.S
index 3cc0f8c..1010d53 100644
--- a/arch/sparc/lib/NG4patch.S
+++ b/arch/sparc/lib/NG4patch.S
@@ -52,3 +52,12 @@ niagara4_patch_pageops:
 	retl
 	 nop
 	.size	niagara4_patch_pageops,.-niagara4_patch_pageops
+
+	.globl	niagara4_patch_fls
+	.type	niagara4_patch_fls,#function
+niagara4_patch_fls:
+	NG_DO_PATCH(fls, NG4fls)
+	NG_DO_PATCH(__fls, __NG4fls)
+	retl
+	 nop
+	.size	niagara4_patch_fls,.-niagara4_patch_fls
-- 
1.7.1

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#1740984

FromSam Ravnborg <sam@ravnborg.org>
Date2017-09-27 22:00 +0200
Message-ID<uuqEX-7nX-29@gated-at.bofh.it>
In reply to#1740960
Hi Vijay.

On Wed, Sep 27, 2017 at 01:25:26PM -0600, Vijay Kumar wrote:
> For T4 and above, patch fls and __fls functions
> at the boot time to use lzcnt instruction.
> 
> Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
> Reviewed-by: Babu Moger <babu.moger@oracle.com>
> ---
>  arch/sparc/Makefile         |    1 +
>  arch/sparc/kernel/head_64.S |    2 ++
>  arch/sparc/lib/Makefile     |    3 +++
>  arch/sparc/lib/NG4fls.S     |   30 ++++++++++++++++++++++++++++++
>  arch/sparc/lib/NG4patch.S   |    9 +++++++++
>  5 files changed, 45 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
> index 8496a07..0763cd8 100644
> --- a/arch/sparc/Makefile
> +++ b/arch/sparc/Makefile
> @@ -48,6 +48,7 @@ KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
>  KBUILD_CFLAGS += -Wa,--undeclared-regs
>  KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
>  KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
> +KBUILD_AFLAGS += -Wa,-Asparc4
This change is not justified anywhere??

>  
>  ifeq ($(CONFIG_MCOUNT),y)
>    KBUILD_CFLAGS += -pg
> diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
> index 78e0211..1165254 100644
> --- a/arch/sparc/kernel/head_64.S
> +++ b/arch/sparc/kernel/head_64.S
> @@ -628,6 +628,8 @@ niagara4_patch:
>  	 nop
>  	call	niagara4_patch_pageops
>  	 nop
> +	call	niagara4_patch_fls
> +	 nop
>  
>  	ba,a,pt	%xcc, 80f
>  	 nop
> diff --git a/arch/sparc/lib/Makefile b/arch/sparc/lib/Makefile
> index eefbb9c..72d2d8c 100644
> --- a/arch/sparc/lib/Makefile
> +++ b/arch/sparc/lib/Makefile
> @@ -46,3 +46,6 @@ lib-$(CONFIG_SPARC64) += mcount.o ipcsum.o xor.o hweight.o ffs.o
>  obj-$(CONFIG_SPARC64) += iomap.o
>  obj-$(CONFIG_SPARC32) += atomic32.o ucmpdi2.o
>  obj-$(CONFIG_SPARC64) += PeeCeeI.o
> +
> +obj-$(CONFIG_SPARC64) += fls.o
> +obj-$(CONFIG_SPARC64) += NG4fls.o
> diff --git a/arch/sparc/lib/NG4fls.S b/arch/sparc/lib/NG4fls.S
> new file mode 100644
> index 0000000..eb239aa
> --- /dev/null
> +++ b/arch/sparc/lib/NG4fls.S
> @@ -0,0 +1,30 @@
> +/* NG4fls.S: SPARC optimized fls and __fls for T4 and above.
> + *
> + * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
> + */
> +
> +	.text
> +	.align 32
> +
> +	.globl NG4fls
> +	.globl __NG4fls
> +	.type  NG4fls, #function
> +	.type  __NG4fls, #function

Use ENTRY(), ENDPROC() as already mentioned.
> +NG4fls:
> +	lzcnt   %o0, %o1
> +	mov     64, %o2
> +	retl
> +	 sub     %o2, %o1, %o0
> +	.size   NG4fls, .-NG4fls
> +
> +__NG4fls:
> +	brz,pn  %o0, 1f
> +        mov	%o0, %o1
Use tabs for indent, not spaces. In this case one tab + one space.

> +	lzcnt	%o1, %o0
> +	mov     63, %o2
> +	sub     %o2, %o0, %o0
> +1:
> +	retl
> +	 nop
> +	.size   __NG4fls, .-__NG4fls
> diff --git a/arch/sparc/lib/NG4patch.S b/arch/sparc/lib/NG4patch.S
> index 3cc0f8c..1010d53 100644
> --- a/arch/sparc/lib/NG4patch.S
> +++ b/arch/sparc/lib/NG4patch.S
> @@ -52,3 +52,12 @@ niagara4_patch_pageops:
>  	retl
>  	 nop
>  	.size	niagara4_patch_pageops,.-niagara4_patch_pageops
> +
> +	.globl	niagara4_patch_fls
> +	.type	niagara4_patch_fls,#function
> +niagara4_patch_fls:
> +	NG_DO_PATCH(fls, NG4fls)
> +	NG_DO_PATCH(__fls, __NG4fls)
> +	retl
> +	 nop
> +	.size	niagara4_patch_fls,.-niagara4_patch_fls

Please path the remaining functions in this file with ENTRY(), ENDPROC() - in a separate patch.

	Sam

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#1741006

FromVijay Kumar <vijay.ac.kumar@oracle.com>
Date2017-09-27 22:30 +0200
Message-ID<uur7X-7Pc-1@gated-at.bofh.it>
In reply to#1740984
Hi Sam,

On 9/27/2017 2:56 PM, Sam Ravnborg wrote:
>>   	.size	niagara4_patch_pageops,.-niagara4_patch_pageops
>> +
>> +	.globl	niagara4_patch_fls
>> +	.type	niagara4_patch_fls,#function
>> +niagara4_patch_fls:
>> +	NG_DO_PATCH(fls, NG4fls)
>> +	NG_DO_PATCH(__fls, __NG4fls)
>> +	retl
>> +	 nop
>> +	.size	niagara4_patch_fls,.-niagara4_patch_fls
> Please path the remaining functions in this file with ENTRY(), ENDPROC() - in a separate patch.

Thanks for your comment. Sure, I will make the changes and address other 
comments as well in my revised version.

- Vijay

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#1741023

FromDavid Miller <davem@davemloft.net>
Date2017-09-27 23:10 +0200
Message-ID<uurKG-8gU-7@gated-at.bofh.it>
In reply to#1740984
From: Sam Ravnborg <sam@ravnborg.org>
Date: Wed, 27 Sep 2017 21:56:37 +0200

> Hi Vijay.
> 
> On Wed, Sep 27, 2017 at 01:25:26PM -0600, Vijay Kumar wrote:
>> For T4 and above, patch fls and __fls functions
>> at the boot time to use lzcnt instruction.
>> 
>> Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
>> Reviewed-by: Babu Moger <babu.moger@oracle.com>
>> ---
>>  arch/sparc/Makefile         |    1 +
>>  arch/sparc/kernel/head_64.S |    2 ++
>>  arch/sparc/lib/Makefile     |    3 +++
>>  arch/sparc/lib/NG4fls.S     |   30 ++++++++++++++++++++++++++++++
>>  arch/sparc/lib/NG4patch.S   |    9 +++++++++
>>  5 files changed, 45 insertions(+), 0 deletions(-)
>> 
>> diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
>> index 8496a07..0763cd8 100644
>> --- a/arch/sparc/Makefile
>> +++ b/arch/sparc/Makefile
>> @@ -48,6 +48,7 @@ KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
>>  KBUILD_CFLAGS += -Wa,--undeclared-regs
>>  KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
>>  KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
>> +KBUILD_AFLAGS += -Wa,-Asparc4
> This change is not justified anywhere??

It also will likely break with older tools.

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#1741046

FromAnthony Yznaga <anthony.yznaga@oracle.com>
Date2017-09-27 23:50 +0200
Message-ID<uusno-8uO-21@gated-at.bofh.it>
In reply to#1740984
> On Sep 27, 2017, at 12:56 PM, Sam Ravnborg <sam@ravnborg.org> wrote:
> 
> Hi Vijay.
> 
> On Wed, Sep 27, 2017 at 01:25:26PM -0600, Vijay Kumar wrote:
>> For T4 and above, patch fls and __fls functions
>> at the boot time to use lzcnt instruction.
>> 
>> Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
>> Reviewed-by: Babu Moger <babu.moger@oracle.com>
>> ---
>> arch/sparc/Makefile         |    1 +
>> arch/sparc/kernel/head_64.S |    2 ++
>> arch/sparc/lib/Makefile     |    3 +++
>> arch/sparc/lib/NG4fls.S     |   30 ++++++++++++++++++++++++++++++
>> arch/sparc/lib/NG4patch.S   |    9 +++++++++
>> 5 files changed, 45 insertions(+), 0 deletions(-)
>> 
>> diff --git a/arch/sparc/Makefile b/arch/sparc/Makefile
>> index 8496a07..0763cd8 100644
>> --- a/arch/sparc/Makefile
>> +++ b/arch/sparc/Makefile
>> @@ -48,6 +48,7 @@ KBUILD_CFLAGS += -ffixed-g4 -ffixed-g5 -fcall-used-g7 -Wno-sign-compare
>> KBUILD_CFLAGS += -Wa,--undeclared-regs
>> KBUILD_CFLAGS += $(call cc-option,-mtune=ultrasparc3)
>> KBUILD_AFLAGS += -m64 -mcpu=ultrasparc -Wa,--undeclared-regs
>> +KBUILD_AFLAGS += -Wa,-Asparc4
> This change is not justified anywhere??

It looks like this is to get the assembler to recognize the lzcnt instruction.

Vijay,
Older assemblers may not support this flag so you’ll need to hardcode the lzcnt instructions using .word directives.

Anthony

> 
>> 
>> ifeq ($(CONFIG_MCOUNT),y)
>>   KBUILD_CFLAGS += -pg
>> diff --git a/arch/sparc/kernel/head_64.S b/arch/sparc/kernel/head_64.S
>> index 78e0211..1165254 100644
>> --- a/arch/sparc/kernel/head_64.S
>> +++ b/arch/sparc/kernel/head_64.S
>> @@ -628,6 +628,8 @@ niagara4_patch:
>> 	 nop
>> 	call	niagara4_patch_pageops
>> 	 nop
>> +	call	niagara4_patch_fls
>> +	 nop
>> 
>> 	ba,a,pt	%xcc, 80f
>> 	 nop
>> diff --git a/arch/sparc/lib/Makefile b/arch/sparc/lib/Makefile
>> index eefbb9c..72d2d8c 100644
>> --- a/arch/sparc/lib/Makefile
>> +++ b/arch/sparc/lib/Makefile
>> @@ -46,3 +46,6 @@ lib-$(CONFIG_SPARC64) += mcount.o ipcsum.o xor.o hweight.o ffs.o
>> obj-$(CONFIG_SPARC64) += iomap.o
>> obj-$(CONFIG_SPARC32) += atomic32.o ucmpdi2.o
>> obj-$(CONFIG_SPARC64) += PeeCeeI.o
>> +
>> +obj-$(CONFIG_SPARC64) += fls.o
>> +obj-$(CONFIG_SPARC64) += NG4fls.o
>> diff --git a/arch/sparc/lib/NG4fls.S b/arch/sparc/lib/NG4fls.S
>> new file mode 100644
>> index 0000000..eb239aa
>> --- /dev/null
>> +++ b/arch/sparc/lib/NG4fls.S
>> @@ -0,0 +1,30 @@
>> +/* NG4fls.S: SPARC optimized fls and __fls for T4 and above.
>> + *
>> + * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
>> + */
>> +
>> +	.text
>> +	.align 32
>> +
>> +	.globl NG4fls
>> +	.globl __NG4fls
>> +	.type  NG4fls, #function
>> +	.type  __NG4fls, #function
> 
> Use ENTRY(), ENDPROC() as already mentioned.
>> +NG4fls:
>> +	lzcnt   %o0, %o1
>> +	mov     64, %o2
>> +	retl
>> +	 sub     %o2, %o1, %o0
>> +	.size   NG4fls, .-NG4fls
>> +
>> +__NG4fls:
>> +	brz,pn  %o0, 1f
>> +        mov	%o0, %o1
> Use tabs for indent, not spaces. In this case one tab + one space.
> 
>> +	lzcnt	%o1, %o0
>> +	mov     63, %o2
>> +	sub     %o2, %o0, %o0
>> +1:
>> +	retl
>> +	 nop
>> +	.size   __NG4fls, .-__NG4fls
>> diff --git a/arch/sparc/lib/NG4patch.S b/arch/sparc/lib/NG4patch.S
>> index 3cc0f8c..1010d53 100644
>> --- a/arch/sparc/lib/NG4patch.S
>> +++ b/arch/sparc/lib/NG4patch.S
>> @@ -52,3 +52,12 @@ niagara4_patch_pageops:
>> 	retl
>> 	 nop
>> 	.size	niagara4_patch_pageops,.-niagara4_patch_pageops
>> +
>> +	.globl	niagara4_patch_fls
>> +	.type	niagara4_patch_fls,#function
>> +niagara4_patch_fls:
>> +	NG_DO_PATCH(fls, NG4fls)
>> +	NG_DO_PATCH(__fls, __NG4fls)
>> +	retl
>> +	 nop
>> +	.size	niagara4_patch_fls,.-niagara4_patch_fls
> 
> Please path the remaining functions in this file with ENTRY(), ENDPROC() - in a separate patch.
> 
> 	Sam
> --
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#1741069

FromDavid Miller <davem@davemloft.net>
Date2017-09-28 00:20 +0200
Message-ID<uusQp-sS-11@gated-at.bofh.it>
In reply to#1741046
From: Anthony Yznaga <anthony.yznaga@oracle.com>
Date: Wed, 27 Sep 2017 14:45:34 -0700

> Vijay,
> Older assemblers may not support this flag so you’ll need to
> hardcode the lzcnt instructions using .word directives.

Right, older binutils do not support the T4 instructions.

This is why we hardcode the opcodes for all of the crypto
instructions used under arch/sparc64/crypto/, for example.

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