Re: [PATCH] powerpc: Add a local_flush_tlb_page to handle kmap_atomic invalidates

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Wed, 2008-11-19 at 09:53 -0600, Kumar Gala wrote:
> The tlb invalidates in kmap_atomic/kunmap_atomic can be called from
> IRQ context, however they are only local invalidates (on the processor
> that the kmap was called on).  In the future we want to use IPIs to
> do tlb invalidates this causes issue since flush_tlb_page() is considered
> a broadcast invalidate.
> 
> Add local_flush_tlb_page() as a non-broadcast invalidate and use it in
> kmap_atomic() since we don't have enough information in the
> flush_tlb_page() call to determine its local.
> 
> Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

> ---
>  arch/powerpc/include/asm/highmem.h  |    4 ++--
>  arch/powerpc/include/asm/tlbflush.h |   14 ++++++++++++++
>  2 files changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/highmem.h b/arch/powerpc/include/asm/highmem.h
> index 91c5895..7dc52ec 100644
> --- a/arch/powerpc/include/asm/highmem.h
> +++ b/arch/powerpc/include/asm/highmem.h
> @@ -85,7 +85,7 @@ static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgpro
>  	BUG_ON(!pte_none(*(kmap_pte-idx)));
>  #endif
>  	__set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
> -	flush_tlb_page(NULL, vaddr);
> +	local_flush_tlb_page(vaddr);
>  
>  	return (void*) vaddr;
>  }
> @@ -113,7 +113,7 @@ static inline void kunmap_atomic(void *kvaddr, enum km_type type)
>  	 * this pte without first remap it
>  	 */
>  	pte_clear(&init_mm, vaddr, kmap_pte-idx);
> -	flush_tlb_page(NULL, vaddr);
> +	local_flush_tlb_page(vaddr);
>  #endif
>  	pagefault_enable();
>  }
> diff --git a/arch/powerpc/include/asm/tlbflush.h b/arch/powerpc/include/asm/tlbflush.h
> index a2c6bfd..93716a9 100644
> --- a/arch/powerpc/include/asm/tlbflush.h
> +++ b/arch/powerpc/include/asm/tlbflush.h
> @@ -6,6 +6,7 @@
>   *
>   *  - flush_tlb_mm(mm) flushes the specified mm context TLB's
>   *  - flush_tlb_page(vma, vmaddr) flushes one page
> + *  - local_flush_tlb_page(vmaddr) flushes one page on the local processor
>   *  - flush_tlb_page_nohash(vma, vmaddr) flushes one page if SW loaded TLB
>   *  - flush_tlb_range(vma, start, end) flushes a range of pages
>   *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
> @@ -44,6 +45,11 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
>  	_tlbil_pid(mm->context.id);
>  }
>  
> +static inline void local_flush_tlb_page(unsigned long vmaddr)
> +{
> +	_tlbil_va(vmaddr, 0);
> +}
> +
>  static inline void flush_tlb_page(struct vm_area_struct *vma,
>  				  unsigned long vmaddr)
>  {
> @@ -81,6 +87,10 @@ extern void flush_tlb_page_nohash(struct vm_area_struct *vma, unsigned long addr
>  extern void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
>  			    unsigned long end);
>  extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
> +static inline void local_flush_tlb_page(unsigned long vmaddr)
> +{
> +	flush_tlb_page(NULL, vmaddr);
> +}
>  
>  #else
>  /*
> @@ -138,6 +148,10 @@ static inline void flush_tlb_mm(struct mm_struct *mm)
>  {
>  }
>  
> +static inline void local_flush_tlb_page(unsigned long vmaddr)
> +{
> +}
> +
>  static inline void flush_tlb_page(struct vm_area_struct *vma,
>  				  unsigned long vmaddr)
>  {