[1/2] arc: rename xCCM sections so they are not merged in global .data/.text

If Linux kernel is compiled with "-ffunction-sections" each function is placed in
its own section named ".text.function_name". This is required for
discarding of not-used functions during final linkage. But in the end
all ".text.XXX" sections are merged in the global ".text" section of
vmlinux Elf.

The same happens with data sections when "-fdata-sections" are used.

That means our ".data.arcfp" and ".text.arcfp" sections get silently
merged in global ".data" and ".text" sections even though we want to
put them in separate memory regions in case ICCM and/or DCCM exist in
the ARC core.

Solution is as simple as addition of one extra period in section name.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Igor Guryanov <guryanov@synopsys.com>
Cc: stable@vger.kernel.org
---
 arch/arc/include/asm/linkage.h | 6 +++---
 arch/arc/kernel/vmlinux.lds.S  | 8 ++++----
 2 files changed, 7 insertions(+), 7 deletions(-)

On 12/22/2016 06:09 AM, Alexey Brodkin wrote:
> If Linux kernel is compiled with "-ffunction-sections" each function is placed in
> its own section named ".text.function_name". This is required for
> discarding of not-used functions during final linkage. But in the end
> all ".text.XXX" sections are merged in the global ".text" section of
> vmlinux Elf.
>
> The same happens with data sections when "-fdata-sections" are used.
>
> That means our ".data.arcfp" and ".text.arcfp" sections get silently
> merged in global ".data" and ".text" sections even though we want to
> put them in separate memory regions in case ICCM and/or DCCM exist in
> the ARC core.
>
> Solution is as simple as addition of one extra period in section name.
>
> Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
> Cc: Igor Guryanov <guryanov@synopsys.com>
> Cc: stable@vger.kernel.org

For stable backport -I think there is no point in CC'ing them initially.
Better to make a note in the patch and conclude at the time of patch review and I
can in the end add the CC tag so this gets pulled automatically w/o CC'ing the
stable mailing list at all !

> ---
>  arch/arc/include/asm/linkage.h | 6 +++---
>  arch/arc/kernel/vmlinux.lds.S  | 8 ++++----
>  2 files changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arc/include/asm/linkage.h b/arch/arc/include/asm/linkage.h
> index b29f1a9fd6f7..3a5f13d65ee1 100644
> --- a/arch/arc/include/asm/linkage.h
> +++ b/arch/arc/include/asm/linkage.h
> @@ -28,7 +28,7 @@
>  /* annotation for data we want in DCCM - if enabled in .config */
>  .macro ARCFP_CODE
>  #ifdef CONFIG_ARC_HAS_ICCM
> -	.section .text.arcfp, "ax",@progbits
> +	.section .text..arcfp, "ax",@progbits

Why not turn this around and call it arcfp.text and arcfp.data etc - just like
done for other special sections such as sched, cpuidle, lock... Just so we are
consistent with normal kernel convention !

>  #else
>  	.section .text, "ax",@progbits
>  #endif
> @@ -47,13 +47,13 @@
>  #else	/* !__ASSEMBLY__ */
>  
>  #ifdef CONFIG_ARC_HAS_ICCM
> -#define __arcfp_code __attribute__((__section__(".text.arcfp")))
> +#define __arcfp_code __attribute__((__section__(".text..arcfp")))
>  #else
>  #define __arcfp_code __attribute__((__section__(".text")))
>  #endif
>  
>  #ifdef CONFIG_ARC_HAS_DCCM
> -#define __arcfp_data __attribute__((__section__(".data.arcfp")))
> +#define __arcfp_data __attribute__((__section__(".data..arcfp")))
>  #else
>  #define __arcfp_data __attribute__((__section__(".data")))
>  #endif
> diff --git a/arch/arc/kernel/vmlinux.lds.S b/arch/arc/kernel/vmlinux.lds.S
> index f35ed578e007..f69ae479ee73 100644
> --- a/arch/arc/kernel/vmlinux.lds.S
> +++ b/arch/arc/kernel/vmlinux.lds.S
> @@ -37,8 +37,8 @@ SECTIONS
>  	}
>  
>  #ifdef CONFIG_ARC_HAS_ICCM
> -	.text.arcfp : {
> -		*(.text.arcfp)
> +	.text..arcfp : {
> +		*(.text..arcfp)
>  		. = ALIGN(CONFIG_ARC_ICCM_SZ * 1024);
>  	}
>  #endif
> @@ -151,8 +151,8 @@ SECTIONS
>  #ifdef CONFIG_ARC_HAS_DCCM
>  	. = CONFIG_ARC_DCCM_BASE;
>  	__arc_dccm_base = .;
> -	.data.arcfp : {
> -		*(.data.arcfp)
> +	.data..arcfp : {
> +		*(.data..arcfp)
>  	}
>  	. = ALIGN(CONFIG_ARC_DCCM_SZ * 1024);
>  #endif

Hi Vineet,

On Thu, 2016-12-22 at 16:25 -0800, Vineet Gupta wrote:
> On 12/22/2016 06:09 AM, Alexey Brodkin wrote:

> > diff --git a/arch/arc/include/asm/linkage.h b/arch/arc/include/asm/linkage.h

> > index b29f1a9fd6f7..3a5f13d65ee1 100644

> > --- a/arch/arc/include/asm/linkage.h

> > +++ b/arch/arc/include/asm/linkage.h

> > @@ -28,7 +28,7 @@

> >  /* annotation for data we want in DCCM - if enabled in .config */

> >  .macro ARCFP_CODE

> >  #ifdef CONFIG_ARC_HAS_ICCM

> > -	.section .text.arcfp, "ax",@progbits

> > +	.section .text..arcfp, "ax",@progbits

> 

> Why not turn this around and call it arcfp.text and arcfp.data etc - just like

> done for other special sections such as sched, cpuidle, lock... Just so we are

> consistent with normal kernel convention !


Right that looks much better!
Will do so in v2.

-Alexey