1 /* asm-generic/tlb.h 2 * 3 * Generic TLB shootdown code 4 * 5 * Copyright 2001 Red Hat, Inc. 6 * Based on code from mm/memory.c Copyright Linus Torvalds and others. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 11 * 2 of the License, or (at your option) any later version. 12 */ 13 #ifndef _ASM_GENERIC__TLB_H 14 #define _ASM_GENERIC__TLB_H 15 16 #include <linux/config.h> 17 #include <linux/swap.h> 18 #include <asm/pgalloc.h> 19 #include <asm/tlbflush.h> 20 21 /* 22 * For UP we don't need to worry about TLB flush 23 * and page free order so much.. 24 */ 25 #ifdef CONFIG_SMP 26 #define FREE_PTE_NR 506 27 #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) 28 #else 29 #define FREE_PTE_NR 1 30 #define tlb_fast_mode(tlb) 1 31 #endif 32 33 /* struct mmu_gather is an opaque type used by the mm code for passing around 34 * any data needed by arch specific code for tlb_remove_page. This structure 35 * can be per-CPU or per-MM as the page table lock is held for the duration of 36 * TLB shootdown. 37 */ 38 struct mmu_gather { 39 struct mm_struct *mm; 40 unsigned int nr; /* set to ~0U means fast mode */ 41 unsigned int need_flush;/* Really unmapped some ptes? */ 42 unsigned int fullmm; /* non-zero means full mm flush */ 43 unsigned long freed; 44 struct page * pages[FREE_PTE_NR]; 45 }; 46 47 /* Users of the generic TLB shootdown code must declare this storage space. */ 48 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); 49 50 /* tlb_gather_mmu 51 * Return a pointer to an initialized struct mmu_gather. 52 */ 53 static inline struct mmu_gather * 54 tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush) 55 { 56 struct mmu_gather *tlb = &per_cpu(mmu_gathers, smp_processor_id()); 57 58 tlb->mm = mm; 59 60 /* Use fast mode if only one CPU is online */ 61 tlb->nr = num_online_cpus() > 1 ? 0U : ~0U; 62 63 tlb->fullmm = full_mm_flush; 64 tlb->freed = 0; 65 66 return tlb; 67 } 68 69 static inline void 70 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 71 { 72 if (!tlb->need_flush) 73 return; 74 tlb->need_flush = 0; 75 tlb_flush(tlb); 76 if (!tlb_fast_mode(tlb)) { 77 free_pages_and_swap_cache(tlb->pages, tlb->nr); 78 tlb->nr = 0; 79 } 80 } 81 82 /* tlb_finish_mmu 83 * Called at the end of the shootdown operation to free up any resources 84 * that were required. The page table lock is still held at this point. 85 */ 86 static inline void 87 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 88 { 89 int freed = tlb->freed; 90 struct mm_struct *mm = tlb->mm; 91 int rss = get_mm_counter(mm, rss); 92 93 if (rss < freed) 94 freed = rss; 95 add_mm_counter(mm, rss, -freed); 96 tlb_flush_mmu(tlb, start, end); 97 98 /* keep the page table cache within bounds */ 99 check_pgt_cache(); 100 } 101 102 static inline unsigned int 103 tlb_is_full_mm(struct mmu_gather *tlb) 104 { 105 return tlb->fullmm; 106 } 107 108 /* tlb_remove_page 109 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 110 * handling the additional races in SMP caused by other CPUs caching valid 111 * mappings in their TLBs. 112 */ 113 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) 114 { 115 tlb->need_flush = 1; 116 if (tlb_fast_mode(tlb)) { 117 free_page_and_swap_cache(page); 118 return; 119 } 120 tlb->pages[tlb->nr++] = page; 121 if (tlb->nr >= FREE_PTE_NR) 122 tlb_flush_mmu(tlb, 0, 0); 123 } 124 125 /** 126 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. 127 * 128 * Record the fact that pte's were really umapped in ->need_flush, so we can 129 * later optimise away the tlb invalidate. This helps when userspace is 130 * unmapping already-unmapped pages, which happens quite a lot. 131 */ 132 #define tlb_remove_tlb_entry(tlb, ptep, address) \ 133 do { \ 134 tlb->need_flush = 1; \ 135 __tlb_remove_tlb_entry(tlb, ptep, address); \ 136 } while (0) 137 138 #define pte_free_tlb(tlb, ptep) \ 139 do { \ 140 tlb->need_flush = 1; \ 141 __pte_free_tlb(tlb, ptep); \ 142 } while (0) 143 144 #ifndef __ARCH_HAS_4LEVEL_HACK 145 #define pud_free_tlb(tlb, pudp) \ 146 do { \ 147 tlb->need_flush = 1; \ 148 __pud_free_tlb(tlb, pudp); \ 149 } while (0) 150 #endif 151 152 #define pmd_free_tlb(tlb, pmdp) \ 153 do { \ 154 tlb->need_flush = 1; \ 155 __pmd_free_tlb(tlb, pmdp); \ 156 } while (0) 157 158 #define tlb_migrate_finish(mm) do {} while (0) 159 160 #endif /* _ASM_GENERIC__TLB_H */ 161