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 #ifdef ARCH_FREE_PTR_NR 27 #define FREE_PTR_NR ARCH_FREE_PTR_NR 28 #else 29 #define FREE_PTE_NR 506 30 #endif 31 #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) 32 #else 33 #define FREE_PTE_NR 1 34 #define tlb_fast_mode(tlb) 1 35 #endif 36 37 /* struct mmu_gather is an opaque type used by the mm code for passing around 38 * any data needed by arch specific code for tlb_remove_page. 39 */ 40 struct mmu_gather { 41 struct mm_struct *mm; 42 unsigned int nr; /* set to ~0U means fast mode */ 43 unsigned int need_flush;/* Really unmapped some ptes? */ 44 unsigned int fullmm; /* non-zero means full mm flush */ 45 struct page * pages[FREE_PTE_NR]; 46 }; 47 48 /* Users of the generic TLB shootdown code must declare this storage space. */ 49 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); 50 51 /* tlb_gather_mmu 52 * Return a pointer to an initialized struct mmu_gather. 53 */ 54 static inline struct mmu_gather * 55 tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush) 56 { 57 struct mmu_gather *tlb = &get_cpu_var(mmu_gathers); 58 59 tlb->mm = mm; 60 61 /* Use fast mode if only one CPU is online */ 62 tlb->nr = num_online_cpus() > 1 ? 0U : ~0U; 63 64 tlb->fullmm = full_mm_flush; 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. 85 */ 86 static inline void 87 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 88 { 89 tlb_flush_mmu(tlb, start, end); 90 91 /* keep the page table cache within bounds */ 92 check_pgt_cache(); 93 94 put_cpu_var(mmu_gathers); 95 } 96 97 /* tlb_remove_page 98 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 99 * handling the additional races in SMP caused by other CPUs caching valid 100 * mappings in their TLBs. 101 */ 102 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) 103 { 104 tlb->need_flush = 1; 105 if (tlb_fast_mode(tlb)) { 106 free_page_and_swap_cache(page); 107 return; 108 } 109 tlb->pages[tlb->nr++] = page; 110 if (tlb->nr >= FREE_PTE_NR) 111 tlb_flush_mmu(tlb, 0, 0); 112 } 113 114 /** 115 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation. 116 * 117 * Record the fact that pte's were really umapped in ->need_flush, so we can 118 * later optimise away the tlb invalidate. This helps when userspace is 119 * unmapping already-unmapped pages, which happens quite a lot. 120 */ 121 #define tlb_remove_tlb_entry(tlb, ptep, address) \ 122 do { \ 123 tlb->need_flush = 1; \ 124 __tlb_remove_tlb_entry(tlb, ptep, address); \ 125 } while (0) 126 127 #define pte_free_tlb(tlb, ptep) \ 128 do { \ 129 tlb->need_flush = 1; \ 130 __pte_free_tlb(tlb, ptep); \ 131 } while (0) 132 133 #ifndef __ARCH_HAS_4LEVEL_HACK 134 #define pud_free_tlb(tlb, pudp) \ 135 do { \ 136 tlb->need_flush = 1; \ 137 __pud_free_tlb(tlb, pudp); \ 138 } while (0) 139 #endif 140 141 #define pmd_free_tlb(tlb, pmdp) \ 142 do { \ 143 tlb->need_flush = 1; \ 144 __pmd_free_tlb(tlb, pmdp); \ 145 } while (0) 146 147 #define tlb_migrate_finish(mm) do {} while (0) 148 149 #endif /* _ASM_GENERIC__TLB_H */ 150