From c7cc58a1ad8dfe3c199d3b6ce50412b86dd3edaf Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Thu, 23 Jul 2009 23:15:28 +0000 Subject: [PATCH] powerpc/mm: Rework & cleanup page table freeing code path That patch used to just add a hook to page table flushing but pulling that string brought out a whole bunch of issues, so it now does that and more: - We now make the RCU batching of page freeing SMP only, as I believe it was intended initially. We make a few more things compile to nothing on !CONFIG_SMP - Some macros are turned into functions, though that forced me to out of line a few stuffs due to unsolvable include depenencies, however it's probably better that way anyway, it's not -that- critical code path. - 32-bit didn't call pte_free_finish() on tlb_flush() which means that it wouldn't push out the batch to RCU for delayed freeing when a bunch of page tables have been freed, they would just stay in there until the batch gets full. 64-bit BookE will use that hook to maintain the virtually linear page tables or the indirect entries in the TLB when using the HW loader. Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/pgalloc.h | 39 +++++++++++++++++++++--------- arch/powerpc/include/asm/tlb.h | 38 +++-------------------------- arch/powerpc/mm/pgtable.c | 10 ++++++++ arch/powerpc/mm/tlb_hash32.c | 3 +++ arch/powerpc/mm/tlb_hash64.c | 15 ++++++++++++ arch/powerpc/mm/tlb_nohash.c | 8 ++++++ 6 files changed, 67 insertions(+), 46 deletions(-) diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h index 1730e5e298d6..34b080671f00 100644 --- a/arch/powerpc/include/asm/pgalloc.h +++ b/arch/powerpc/include/asm/pgalloc.h @@ -4,6 +4,15 @@ #include +#ifdef CONFIG_PPC_BOOK3E +extern void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address); +#else /* CONFIG_PPC_BOOK3E */ +static inline void tlb_flush_pgtable(struct mmu_gather *tlb, + unsigned long address) +{ +} +#endif /* !CONFIG_PPC_BOOK3E */ + static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte) { free_page((unsigned long)pte); @@ -35,19 +44,27 @@ static inline pgtable_free_t pgtable_free_cache(void *p, int cachenum, #include #endif -extern void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf); - #ifdef CONFIG_SMP -#define __pte_free_tlb(tlb,ptepage,address) \ -do { \ - pgtable_page_dtor(ptepage); \ - pgtable_free_tlb(tlb, pgtable_free_cache(page_address(ptepage), \ - PTE_NONCACHE_NUM, PTE_TABLE_SIZE-1)); \ -} while (0) -#else -#define __pte_free_tlb(tlb, pte, address) pte_free((tlb)->mm, (pte)) -#endif +extern void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf); +extern void pte_free_finish(void); +#else /* CONFIG_SMP */ +static inline void pgtable_free_tlb(struct mmu_gather *tlb, pgtable_free_t pgf) +{ + pgtable_free(pgf); +} +static inline void pte_free_finish(void) { } +#endif /* !CONFIG_SMP */ +static inline void __pte_free_tlb(struct mmu_gather *tlb, struct page *ptepage, + unsigned long address) +{ + pgtable_free_t pgf = pgtable_free_cache(page_address(ptepage), + PTE_NONCACHE_NUM, + PTE_TABLE_SIZE-1); + tlb_flush_pgtable(tlb, address); + pgtable_page_dtor(ptepage); + pgtable_free_tlb(tlb, pgf); +} #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_PGALLOC_H */ diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h index e20ff7541f36..e2b428b0f7ba 100644 --- a/arch/powerpc/include/asm/tlb.h +++ b/arch/powerpc/include/asm/tlb.h @@ -25,57 +25,25 @@ #include -struct mmu_gather; - #define tlb_start_vma(tlb, vma) do { } while (0) #define tlb_end_vma(tlb, vma) do { } while (0) -#if !defined(CONFIG_PPC_STD_MMU) - -#define tlb_flush(tlb) flush_tlb_mm((tlb)->mm) - -#elif defined(__powerpc64__) - -extern void pte_free_finish(void); - -static inline void tlb_flush(struct mmu_gather *tlb) -{ - struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch); - - /* If there's a TLB batch pending, then we must flush it because the - * pages are going to be freed and we really don't want to have a CPU - * access a freed page because it has a stale TLB - */ - if (tlbbatch->index) - __flush_tlb_pending(tlbbatch); - - pte_free_finish(); -} - -#else - extern void tlb_flush(struct mmu_gather *tlb); -#endif - /* Get the generic bits... */ #include -#if !defined(CONFIG_PPC_STD_MMU) || defined(__powerpc64__) - -#define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0) - -#else extern void flush_hash_entry(struct mm_struct *mm, pte_t *ptep, unsigned long address); static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, - unsigned long address) + unsigned long address) { +#ifdef CONFIG_PPC_STD_MMU_32 if (pte_val(*ptep) & _PAGE_HASHPTE) flush_hash_entry(tlb->mm, ptep, address); +#endif } -#endif #endif /* __KERNEL__ */ #endif /* __ASM_POWERPC_TLB_H */ diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c index 627767d6169b..a65979a5f75b 100644 --- a/arch/powerpc/mm/pgtable.c +++ b/arch/powerpc/mm/pgtable.c @@ -30,6 +30,14 @@ #include #include +#ifdef CONFIG_SMP + +/* + * Handle batching of page table freeing on SMP. Page tables are + * queued up and send to be freed later by RCU in order to avoid + * freeing a page table page that is being walked without locks + */ + static DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur); static unsigned long pte_freelist_forced_free; @@ -116,6 +124,8 @@ void pte_free_finish(void) *batchp = NULL; } +#endif /* CONFIG_SMP */ + /* * Handle i/d cache flushing, called from set_pte_at() or ptep_set_access_flags() */ diff --git a/arch/powerpc/mm/tlb_hash32.c b/arch/powerpc/mm/tlb_hash32.c index 65190587a365..8aaa8b7eb324 100644 --- a/arch/powerpc/mm/tlb_hash32.c +++ b/arch/powerpc/mm/tlb_hash32.c @@ -71,6 +71,9 @@ void tlb_flush(struct mmu_gather *tlb) */ _tlbia(); } + + /* Push out batch of freed page tables */ + pte_free_finish(); } /* diff --git a/arch/powerpc/mm/tlb_hash64.c b/arch/powerpc/mm/tlb_hash64.c index 937eb90677d9..8e35a6066938 100644 --- a/arch/powerpc/mm/tlb_hash64.c +++ b/arch/powerpc/mm/tlb_hash64.c @@ -154,6 +154,21 @@ void __flush_tlb_pending(struct ppc64_tlb_batch *batch) batch->index = 0; } +void tlb_flush(struct mmu_gather *tlb) +{ + struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch); + + /* If there's a TLB batch pending, then we must flush it because the + * pages are going to be freed and we really don't want to have a CPU + * access a freed page because it has a stale TLB + */ + if (tlbbatch->index) + __flush_tlb_pending(tlbbatch); + + /* Push out batch of freed page tables */ + pte_free_finish(); +} + /** * __flush_hash_table_range - Flush all HPTEs for a given address range * from the hash table (and the TLB). But keeps diff --git a/arch/powerpc/mm/tlb_nohash.c b/arch/powerpc/mm/tlb_nohash.c index 761e8882416f..6b43fc49f103 100644 --- a/arch/powerpc/mm/tlb_nohash.c +++ b/arch/powerpc/mm/tlb_nohash.c @@ -233,3 +233,11 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start, flush_tlb_mm(vma->vm_mm); } EXPORT_SYMBOL(flush_tlb_range); + +void tlb_flush(struct mmu_gather *tlb) +{ + flush_tlb_mm(tlb->mm); + + /* Push out batch of freed page tables */ + pte_free_finish(); +} -- GitLab