From fb7332a9fedfd62b1ba6530c86f39f0fa38afd49 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 29 Oct 2014 10:03:09 +0000 Subject: [PATCH] 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 --- arch/arm64/include/asm/tlb.h | 67 ++---------------------------- arch/microblaze/include/asm/tlb.h | 3 +- arch/powerpc/include/asm/pgalloc.h | 3 +- arch/powerpc/include/asm/tlb.h | 1 + arch/powerpc/mm/hugetlbpage.c | 2 - include/asm-generic/tlb.h | 57 ++++++++++++++++++++----- mm/memory.c | 30 ++++--------- 7 files changed, 63 insertions(+), 100 deletions(-) diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h index a82c0c5c8b52..c028fe37456f 100644 --- a/arch/arm64/include/asm/tlb.h +++ b/arch/arm64/include/asm/tlb.h @@ -19,10 +19,6 @@ #ifndef __ASM_TLB_H #define __ASM_TLB_H -#define __tlb_remove_pmd_tlb_entry __tlb_remove_pmd_tlb_entry - -#include - #include #include @@ -37,71 +33,22 @@ static inline void __tlb_remove_table(void *_table) #define tlb_remove_entry(tlb, entry) tlb_remove_page(tlb, entry) #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ -/* - * There's three ways the TLB shootdown code is used: - * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region(). - * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called. - * 2. Unmapping all vmas. See exit_mmap(). - * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called. - * Page tables will be freed. - * 3. Unmapping argument pages. See shift_arg_pages(). - * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called. - */ +#include + static inline void tlb_flush(struct mmu_gather *tlb) { if (tlb->fullmm) { flush_tlb_mm(tlb->mm); - } else if (tlb->end > 0) { + } else { struct vm_area_struct vma = { .vm_mm = tlb->mm, }; flush_tlb_range(&vma, tlb->start, tlb->end); - tlb->start = TASK_SIZE; - tlb->end = 0; - } -} - -static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr) -{ - if (!tlb->fullmm) { - tlb->start = min(tlb->start, addr); - tlb->end = max(tlb->end, addr + PAGE_SIZE); - } -} - -/* - * Memorize the range for the TLB flush. - */ -static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, - unsigned long addr) -{ - tlb_add_flush(tlb, addr); -} - -/* - * 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. - */ -static inline void tlb_start_vma(struct mmu_gather *tlb, - struct vm_area_struct *vma) -{ - if (!tlb->fullmm) { - tlb->start = TASK_SIZE; - tlb->end = 0; } } -static inline void tlb_end_vma(struct mmu_gather *tlb, - struct vm_area_struct *vma) -{ - if (!tlb->fullmm) - tlb_flush(tlb); -} - static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, unsigned long addr) { pgtable_page_dtor(pte); - tlb_add_flush(tlb, addr); tlb_remove_entry(tlb, pte); } @@ -109,7 +56,6 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr) { - tlb_add_flush(tlb, addr); tlb_remove_entry(tlb, virt_to_page(pmdp)); } #endif @@ -118,15 +64,8 @@ static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pudp, unsigned long addr) { - tlb_add_flush(tlb, addr); tlb_remove_entry(tlb, virt_to_page(pudp)); } #endif -static inline void __tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, - unsigned long address) -{ - tlb_add_flush(tlb, address); -} - #endif diff --git a/arch/microblaze/include/asm/tlb.h b/arch/microblaze/include/asm/tlb.h index 8aa97817cc8c..99b6ded54849 100644 --- a/arch/microblaze/include/asm/tlb.h +++ b/arch/microblaze/include/asm/tlb.h @@ -14,7 +14,6 @@ #define tlb_flush(tlb) flush_tlb_mm((tlb)->mm) #include -#include #ifdef CONFIG_MMU #define tlb_start_vma(tlb, vma) do { } while (0) @@ -22,4 +21,6 @@ #define __tlb_remove_tlb_entry(tlb, pte, address) do { } while (0) #endif +#include + #endif /* _ASM_MICROBLAZE_TLB_H */ diff --git a/arch/powerpc/include/asm/pgalloc.h b/arch/powerpc/include/asm/pgalloc.h index e9a9f60e596d..fc3ee06eab87 100644 --- a/arch/powerpc/include/asm/pgalloc.h +++ b/arch/powerpc/include/asm/pgalloc.h @@ -3,7 +3,6 @@ #ifdef __KERNEL__ #include -#include #ifdef CONFIG_PPC_BOOK3E extern void tlb_flush_pgtable(struct mmu_gather *tlb, unsigned long address); @@ -14,6 +13,8 @@ static inline void tlb_flush_pgtable(struct mmu_gather *tlb, } #endif /* !CONFIG_PPC_BOOK3E */ +extern void tlb_remove_table(struct mmu_gather *tlb, void *table); + #ifdef CONFIG_PPC64 #include #else diff --git a/arch/powerpc/include/asm/tlb.h b/arch/powerpc/include/asm/tlb.h index e2b428b0f7ba..20733fa518ae 100644 --- a/arch/powerpc/include/asm/tlb.h +++ b/arch/powerpc/include/asm/tlb.h @@ -27,6 +27,7 @@ #define tlb_start_vma(tlb, vma) do { } while (0) #define tlb_end_vma(tlb, vma) do { } while (0) +#define __tlb_remove_tlb_entry __tlb_remove_tlb_entry extern void tlb_flush(struct mmu_gather *tlb); diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index 7e70ae968e5f..6a4a5fcb9730 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -517,8 +517,6 @@ static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshif for (i = 0; i < num_hugepd; i++, hpdp++) hpdp->pd = 0; - tlb->need_flush = 1; - #ifdef CONFIG_PPC_FSL_BOOK3E hugepd_free(tlb, hugepte); #else 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) diff --git a/mm/memory.c b/mm/memory.c index 1cc6bfbd872e..c71edae9ba44 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -220,9 +220,6 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long /* Is it from 0 to ~0? */ tlb->fullmm = !(start | (end+1)); tlb->need_flush_all = 0; - tlb->start = start; - tlb->end = end; - tlb->need_flush = 0; tlb->local.next = NULL; tlb->local.nr = 0; tlb->local.max = ARRAY_SIZE(tlb->__pages); @@ -232,15 +229,20 @@ void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long #ifdef CONFIG_HAVE_RCU_TABLE_FREE tlb->batch = NULL; #endif + + __tlb_reset_range(tlb); } static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) { - tlb->need_flush = 0; + if (!tlb->end) + return; + tlb_flush(tlb); #ifdef CONFIG_HAVE_RCU_TABLE_FREE tlb_table_flush(tlb); #endif + __tlb_reset_range(tlb); } static void tlb_flush_mmu_free(struct mmu_gather *tlb) @@ -256,8 +258,6 @@ static void tlb_flush_mmu_free(struct mmu_gather *tlb) void tlb_flush_mmu(struct mmu_gather *tlb) { - if (!tlb->need_flush) - return; tlb_flush_mmu_tlbonly(tlb); tlb_flush_mmu_free(tlb); } @@ -292,7 +292,7 @@ int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) { struct mmu_gather_batch *batch; - VM_BUG_ON(!tlb->need_flush); + VM_BUG_ON(!tlb->end); batch = tlb->active; batch->pages[batch->nr++] = page; @@ -359,8 +359,6 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table) { struct mmu_table_batch **batch = &tlb->batch; - tlb->need_flush = 1; - /* * When there's less then two users of this mm there cannot be a * concurrent page-table walk. @@ -1185,20 +1183,8 @@ again: arch_leave_lazy_mmu_mode(); /* Do the actual TLB flush before dropping ptl */ - if (force_flush) { - unsigned long old_end; - - /* - * Flush the TLB just for the previous segment, - * then update the range to be the remaining - * TLB range. - */ - old_end = tlb->end; - tlb->end = addr; + if (force_flush) tlb_flush_mmu_tlbonly(tlb); - tlb->start = addr; - tlb->end = old_end; - } pte_unmap_unlock(start_pte, ptl); /* -- 2.20.1