From fb7332a9fedfd62b1ba6530c86f39f0fa38afd49 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 29 Oct 2014 10:03:09 +0000 Subject: mmu_gather: move minimal range calculations into generic code On architectures with hardware broadcasting of TLB invalidation messages , it makes sense to reduce the range of the mmu_gather structure when unmapping page ranges based on the dirty address information passed to tlb_remove_tlb_entry. arm64 already does this by directly manipulating the start/end fields of the gather structure, but this confuses the generic code which does not expect these fields to change and can end up calculating invalid, negative ranges when forcing a flush in zap_pte_range. This patch moves the minimal range calculation out of the arm64 code and into the generic implementation, simplifying zap_pte_range in the process (which no longer needs to care about start/end, since they will point to the appropriate ranges already). With the range being tracked by core code, the need_flush flag is dropped in favour of checking that the end of the range has actually been set. Cc: Benjamin Herrenschmidt Cc: Peter Zijlstra Cc: Russell King - ARM Linux Cc: Michal Simek Acked-by: Linus Torvalds Signed-off-by: Will Deacon --- include/asm-generic/tlb.h | 57 ++++++++++++++++++++++++++++++++++++++--------- 1 file changed, 47 insertions(+), 10 deletions(-) (limited to 'include/asm-generic/tlb.h') diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 5672d7ea1fa0..08848050922e 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -96,10 +96,9 @@ struct mmu_gather { #endif unsigned long start; unsigned long end; - unsigned int need_flush : 1, /* Did free PTEs */ /* we are in the middle of an operation to clear * a full mm and can make some optimizations */ - fullmm : 1, + unsigned int fullmm : 1, /* we have performed an operation which * requires a complete flush of the tlb */ need_flush_all : 1; @@ -128,16 +127,54 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) tlb_flush_mmu(tlb); } +static inline void __tlb_adjust_range(struct mmu_gather *tlb, + unsigned long address) +{ + tlb->start = min(tlb->start, address); + tlb->end = max(tlb->end, address + PAGE_SIZE); +} + +static inline void __tlb_reset_range(struct mmu_gather *tlb) +{ + tlb->start = TASK_SIZE; + tlb->end = 0; +} + +/* + * In the case of tlb vma handling, we can optimise these away in the + * case where we're doing a full MM flush. When we're doing a munmap, + * the vmas are adjusted to only cover the region to be torn down. + */ +#ifndef tlb_start_vma +#define tlb_start_vma(tlb, vma) do { } while (0) +#endif + +#define __tlb_end_vma(tlb, vma) \ + do { \ + if (!tlb->fullmm && tlb->end) { \ + tlb_flush(tlb); \ + __tlb_reset_range(tlb); \ + } \ + } while (0) + +#ifndef tlb_end_vma +#define tlb_end_vma __tlb_end_vma +#endif + +#ifndef __tlb_remove_tlb_entry +#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0) +#endif + /** * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. * - * Record the fact that pte's were really umapped in ->need_flush, so we can - * later optimise away the tlb invalidate. This helps when userspace is - * unmapping already-unmapped pages, which happens quite a lot. + * Record the fact that pte's were really unmapped by updating the range, + * so we can later optimise away the tlb invalidate. This helps when + * userspace is unmapping already-unmapped pages, which happens quite a lot. */ #define tlb_remove_tlb_entry(tlb, ptep, address) \ do { \ - tlb->need_flush = 1; \ + __tlb_adjust_range(tlb, address); \ __tlb_remove_tlb_entry(tlb, ptep, address); \ } while (0) @@ -151,27 +188,27 @@ static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) #define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \ do { \ - tlb->need_flush = 1; \ + __tlb_adjust_range(tlb, address); \ __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \ } while (0) #define pte_free_tlb(tlb, ptep, address) \ do { \ - tlb->need_flush = 1; \ + __tlb_adjust_range(tlb, address); \ __pte_free_tlb(tlb, ptep, address); \ } while (0) #ifndef __ARCH_HAS_4LEVEL_HACK #define pud_free_tlb(tlb, pudp, address) \ do { \ - tlb->need_flush = 1; \ + __tlb_adjust_range(tlb, address); \ __pud_free_tlb(tlb, pudp, address); \ } while (0) #endif #define pmd_free_tlb(tlb, pmdp, address) \ do { \ - tlb->need_flush = 1; \ + __tlb_adjust_range(tlb, address); \ __pmd_free_tlb(tlb, pmdp, address); \ } while (0) -- cgit v1.2.3