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    FromBenjamin Herrenschmidt <>
    DateTue, 07 Aug 2007 17:19:50 +1000
    Subject[RFC/PATCH 7/12] ia64 tracks freed page tables addresses
    Until now, ia64 pretty much relied on the start/end arguments
    passed to tlb_finish_mmu() to flush the virtual page tables.
    
    Not only these tend to provide larger ranges than necessary,
    but keeping track in the callers is a pain and I intend to remove
    those from my mmu_gather rework.
    
    This patch uses the newly added "address" arguemnt to pte_free_tlb()
    to track the actual range covered by freed page tables and uses
    that to perform the actual freeing.
    
    Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    ---
     include/asm-ia64/tlb.h |   24 +++++++++++++++++-------
     1 file changed, 17 insertions(+), 7 deletions(-)
    Index: linux-work/include/asm-ia64/tlb.h
    ===================================================================
    --- linux-work.orig/include/asm-ia64/tlb.h	2007-08-06 16:15:18.000000000 +1000
    +++ linux-work/include/asm-ia64/tlb.h	2007-08-06 16:15:18.000000000 +1000
    @@ -61,6 +61,8 @@ struct mmu_gather {
     	unsigned char		need_flush;	/* really unmapped some PTEs? */
     	unsigned long		start_addr;
     	unsigned long		end_addr;
    +	unsigned long		start_pgtable;
    +	unsigned long		end_pgtable;
     	struct page 		*pages[FREE_PTE_NR];
     };
     
    @@ -72,8 +74,10 @@ DECLARE_PER_CPU(struct mmu_gather, mmu_g
      * freed pages that where gathered up to this point.
      */
     static inline void
    -ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
    +ia64_tlb_flush_mmu (struct mmu_gather *tlb)
     {
    +	unsigned long start = tlb->start_addr;
    +	unsigned long end = tlb->end_addr;
     	unsigned int nr;
     
     	if (!tlb->need_flush)
    @@ -107,7 +111,10 @@ ia64_tlb_flush_mmu (struct mmu_gather *t
     		/* flush the address range from the tlb: */
     		flush_tlb_range(&vma, start, end);
     		/* now flush the virt. page-table area mapping the address range: */
    -		flush_tlb_range(&vma, ia64_thash(start), ia64_thash(end));
    +		if (tlb->start_pgtable < tlb->end_pgtable)
    +			flush_tlb_range(&vma,
    +					ia64_thash(tlb->start_pgtable),
    +					ia64_thash(tlb->end_pgtable));
     	}
     
     	/* lastly, release the freed pages */
    @@ -115,7 +122,7 @@ ia64_tlb_flush_mmu (struct mmu_gather *t
     	if (!tlb_fast_mode(tlb)) {
     		unsigned long i;
     		tlb->nr = 0;
    -		tlb->start_addr = ~0UL;
    +		tlb->start_addr = tlb->start_pgtable = ~0UL;
     		for (i = 0; i < nr; ++i)
     			free_page_and_swap_cache(tlb->pages[i]);
     	}
    @@ -145,7 +152,7 @@ tlb_gather_mmu (struct mm_struct *mm, un
     	 */
     	tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
     	tlb->fullmm = full_mm_flush;
    -	tlb->start_addr = ~0UL;
    +	tlb->start_addr = tlb->start_pgtable = ~0UL;
     	return tlb;
     }
     
    @@ -160,7 +167,7 @@ tlb_finish_mmu (struct mmu_gather *tlb, 
     	 * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
     	 * tlb->end_addr.
     	 */
    -	ia64_tlb_flush_mmu(tlb, start, end);
    +	ia64_tlb_flush_mmu(tlb);
     
     	/* keep the page table cache within bounds */
     	check_pgt_cache();
    @@ -184,7 +191,7 @@ tlb_remove_page (struct mmu_gather *tlb,
     	}
     	tlb->pages[tlb->nr++] = page;
     	if (tlb->nr >= FREE_PTE_NR)
    -		ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
    +		ia64_tlb_flush_mmu(tlb);
     }
     
     /*
    @@ -194,7 +201,7 @@ tlb_remove_page (struct mmu_gather *tlb,
     static inline void
     __tlb_remove_tlb_entry (struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
     {
    -	if (tlb->start_addr == ~0UL)
    +	if (tlb->start_addr > address)
     		tlb->start_addr = address;
     	tlb->end_addr = address + PAGE_SIZE;
     }
    @@ -213,6 +220,9 @@ do {							\
     #define pte_free_tlb(tlb, ptep, addr)			\
     do {							\
     	tlb->need_flush = 1;				\
    +	if (tlb->start_pgtable > addr)			\
    +		tlb->start_pgtable = addr;		\
    +	tlb->end_pgtable = (addr + PMD_SIZE) & PMD_MASK;\
     	__pte_free_tlb(tlb, ptep, addr);		\
     } while (0)
     
    -
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