On Fri, 2007-11-30 at 03:14 -0600, Kumar Gala wrote:
> Skip updating the kmap_pte and flushing the TLB if the pte we
> are about to write is the same as the one we wrote last time we
> called kmap_atomic for this km_type.
>
> Also expose the flags to allow a caller to specify their own
> flags for things like non-cacheable IO memory.
>
> ---
>
> This is the starts of some work Ben and I were discussion to allow us to
> use kmap_atomic to access a page size region of PCI CFG space when its
> provided as direct MMIO.
>
> We also intend to provide a means to preload the TLB for SW managed TLB
> machines.
We probably need to move that outside of highmem though...
Cheers,
Ben.
> - k
>
> include/asm-powerpc/highmem.h | 16 +++++++++++++---
> 1 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/include/asm-powerpc/highmem.h b/include/asm-powerpc/highmem.h
> index f7b21ee..a50bb00 100644
> --- a/include/asm-powerpc/highmem.h
> +++ b/include/asm-powerpc/highmem.h
> @@ -73,10 +73,12 @@ static inline void kunmap(struct page *page)
> * be used in IRQ contexts, so in some (very limited) cases we need
> * it.
> */
> -static inline void *kmap_atomic(struct page *page, enum km_type type)
> +static inline void *__kmap_atomic(struct page *page,
> + enum km_type type, unsigned long flags)
> {
> unsigned int idx;
> unsigned long vaddr;
> + pte_t pte;
>
> /* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
> pagefault_disable();
> @@ -88,12 +90,20 @@ static inline void *kmap_atomic(struct page *page, enum
> km_type type)
> #ifdef HIGHMEM_DEBUG
> BUG_ON(!pte_none(*(kmap_pte+idx)));
> #endif
> - set_pte_at(&init_mm, vaddr, kmap_pte+idx, mk_pte(page, kmap_prot));
> - flush_tlb_page(NULL, vaddr);
> + pte = mk_pte(page, flags);
> + if (!pte_same(kmap_pte[idx], pte)) {
> + set_pte_at(&init_mm, vaddr, kmap_pte+idx, pte);
> + flush_tlb_page(NULL, vaddr);
> + }
>
> return (void*) vaddr;
> }
>
> +static inline void *kmap_atomic(struct page *page, enum km_type type)
> +{
> + return __kmap_atomic(page, type, kmap_prot);
> +}
> +
> static inline void kunmap_atomic(void *kvaddr, enum km_type type)
> {
> #ifdef HIGHMEM_DEBUG
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