[PATCH] ARM: nommu: avoid mapping vectors page when !CONFIG_MMU

[PATCH] ARM: nommu: avoid mapping vectors page when !CONFIG_MMU

[Will Deacon]

When running without an MMU, we do not need to install a mapping for the
vectors page. Attempting to do so causes a compile-time error because
install_special_mapping is not defined.

This patch adds compile-time guards to the vector mapping functions
so that we can build nommu configurations once more.

Cc: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/arm/kernel/process.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index e76fcaa..94bbedb 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -483,6 +483,7 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
 	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
 }
 
+#ifdef CONFIG_MMU
 /*
  * The vectors page is always readable from user space for the
  * atomic helpers and the signal restart code.  Let's declare a mapping
@@ -503,3 +504,4 @@ const char *arch_vma_name(struct vm_area_struct *vma)
 {
 	return (vma->vm_start == 0xffff0000) ? "[vectors]" : NULL;
 }
+#endif
-- 
1.7.0.4

[PATCH] ARM: nommu: avoid mapping vectors page when !CONFIG_MMU

[Russell King - ARM Linux]

On Tue, Jan 11, 2011 at 12:02:17PM +0000, Will Deacon wrote:
> When running without an MMU, we do not need to install a mapping for the
> vectors page. Attempting to do so causes a compile-time error because
> install_special_mapping is not defined.
> 
> This patch adds compile-time guards to the vector mapping functions
> so that we can build nommu configurations once more.

I had a similar patch a few days ago doing the same thing... when Greg's
acked it, please submit to the patch system, thanks.

[PATCH] ARM: nommu: avoid mapping vectors page when !CONFIG_MMU

[Greg Ungerer]

Hi Will,

On 11/01/11 22:02, Will Deacon wrote:
> When running without an MMU, we do not need to install a mapping for the
> vectors page. Attempting to do so causes a compile-time error because
> install_special_mapping is not defined.
>
> This patch adds compile-time guards to the vector mapping functions
> so that we can build nommu configurations once more.
>
> Cc: Greg Ungerer<gerg@uclinux.org>
> Signed-off-by: Will Deacon<will.deacon@arm.com>

I hit this a couple of days ago too, looks good.

Acked-by: Greg Ungerer <gerg@uclinux.org>

Regards
Greg


>   arch/arm/kernel/process.c |    2 ++
>   1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index e76fcaa..94bbedb 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -483,6 +483,7 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
>   	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
>   }
>
> +#ifdef CONFIG_MMU
>   /*
>    * The vectors page is always readable from user space for the
>    * atomic helpers and the signal restart code.  Let's declare a mapping
> @@ -503,3 +504,4 @@ const char *arch_vma_name(struct vm_area_struct *vma)
>   {
>   	return (vma->vm_start == 0xffff0000) ? "[vectors]" : NULL;
>   }
> +#endif


-- 
------------------------------------------------------------------------
Greg Ungerer  --  Principal Engineer        EMAIL:     gerg at snapgear.com
SnapGear Group, McAfee                      PHONE:       +61 7 3435 2888
8 Gardner Close,                            FAX:         +61 7 3891 3630
Milton, QLD, 4064, Australia                WEB: http://www.SnapGear.com

[PATCH] ARM: nommu: avoid mapping vectors page when !CONFIG_MMU

[Will Deacon]

Hi Greg,

> > When running without an MMU, we do not need to install a mapping for the
> > vectors page. Attempting to do so causes a compile-time error because
> > install_special_mapping is not defined.
> >
> > This patch adds compile-time guards to the vector mapping functions
> > so that we can build nommu configurations once more.
> >
> > Cc: Greg Ungerer<gerg@uclinux.org>
> > Signed-off-by: Will Deacon<will.deacon@arm.com>
> 
> I hit this a couple of days ago too, looks good.
> 
> Acked-by: Greg Ungerer <gerg@uclinux.org>

Thanks. Submitted to Russell as 6619/1.

Will