1 /* 2 * arch/arm/include/asm/tlb.h 3 * 4 * Copyright (C) 2002 Russell King 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * Experimentation shows that on a StrongARM, it appears to be faster 11 * to use the "invalidate whole tlb" rather than "invalidate single 12 * tlb" for this. 13 * 14 * This appears true for both the process fork+exit case, as well as 15 * the munmap-large-area case. 16 */ 17 #ifndef __ASMARM_TLB_H 18 #define __ASMARM_TLB_H 19 20 #include <asm/cacheflush.h> 21 22 #ifndef CONFIG_MMU 23 24 #include <linux/pagemap.h> 25 26 #define tlb_flush(tlb) ((void) tlb) 27 28 #include <asm-generic/tlb.h> 29 30 #else /* !CONFIG_MMU */ 31 32 #include <linux/swap.h> 33 #include <asm/pgalloc.h> 34 #include <asm/tlbflush.h> 35 36 /* 37 * We need to delay page freeing for SMP as other CPUs can access pages 38 * which have been removed but not yet had their TLB entries invalidated. 39 * Also, as ARMv7 speculative prefetch can drag new entries into the TLB, 40 * we need to apply this same delaying tactic to ensure correct operation. 41 */ 42 #if defined(CONFIG_SMP) || defined(CONFIG_CPU_32v7) 43 #define tlb_fast_mode(tlb) 0 44 #define FREE_PTE_NR 500 45 #else 46 #define tlb_fast_mode(tlb) 1 47 #define FREE_PTE_NR 0 48 #endif 49 50 /* 51 * TLB handling. This allows us to remove pages from the page 52 * tables, and efficiently handle the TLB issues. 53 */ 54 struct mmu_gather { 55 struct mm_struct *mm; 56 unsigned int fullmm; 57 struct vm_area_struct *vma; 58 unsigned long range_start; 59 unsigned long range_end; 60 unsigned int nr; 61 struct page *pages[FREE_PTE_NR]; 62 }; 63 64 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); 65 66 /* 67 * This is unnecessarily complex. There's three ways the TLB shootdown 68 * code is used: 69 * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region(). 70 * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called. 71 * tlb->vma will be non-NULL. 72 * 2. Unmapping all vmas. See exit_mmap(). 73 * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called. 74 * tlb->vma will be non-NULL. Additionally, page tables will be freed. 75 * 3. Unmapping argument pages. See shift_arg_pages(). 76 * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called. 77 * tlb->vma will be NULL. 78 */ 79 static inline void tlb_flush(struct mmu_gather *tlb) 80 { 81 if (tlb->fullmm || !tlb->vma) 82 flush_tlb_mm(tlb->mm); 83 else if (tlb->range_end > 0) { 84 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end); 85 tlb->range_start = TASK_SIZE; 86 tlb->range_end = 0; 87 } 88 } 89 90 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr) 91 { 92 if (!tlb->fullmm) { 93 if (addr < tlb->range_start) 94 tlb->range_start = addr; 95 if (addr + PAGE_SIZE > tlb->range_end) 96 tlb->range_end = addr + PAGE_SIZE; 97 } 98 } 99 100 static inline void tlb_flush_mmu(struct mmu_gather *tlb) 101 { 102 tlb_flush(tlb); 103 if (!tlb_fast_mode(tlb)) { 104 free_pages_and_swap_cache(tlb->pages, tlb->nr); 105 tlb->nr = 0; 106 } 107 } 108 109 static inline struct mmu_gather * 110 tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush) 111 { 112 struct mmu_gather *tlb = &get_cpu_var(mmu_gathers); 113 114 tlb->mm = mm; 115 tlb->fullmm = full_mm_flush; 116 tlb->vma = NULL; 117 tlb->nr = 0; 118 119 return tlb; 120 } 121 122 static inline void 123 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 124 { 125 tlb_flush_mmu(tlb); 126 127 /* keep the page table cache within bounds */ 128 check_pgt_cache(); 129 130 put_cpu_var(mmu_gathers); 131 } 132 133 /* 134 * Memorize the range for the TLB flush. 135 */ 136 static inline void 137 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr) 138 { 139 tlb_add_flush(tlb, addr); 140 } 141 142 /* 143 * In the case of tlb vma handling, we can optimise these away in the 144 * case where we're doing a full MM flush. When we're doing a munmap, 145 * the vmas are adjusted to only cover the region to be torn down. 146 */ 147 static inline void 148 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) 149 { 150 if (!tlb->fullmm) { 151 flush_cache_range(vma, vma->vm_start, vma->vm_end); 152 tlb->vma = vma; 153 tlb->range_start = TASK_SIZE; 154 tlb->range_end = 0; 155 } 156 } 157 158 static inline void 159 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) 160 { 161 if (!tlb->fullmm) 162 tlb_flush(tlb); 163 } 164 165 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) 166 { 167 if (tlb_fast_mode(tlb)) { 168 free_page_and_swap_cache(page); 169 } else { 170 tlb->pages[tlb->nr++] = page; 171 if (tlb->nr >= FREE_PTE_NR) 172 tlb_flush_mmu(tlb); 173 } 174 } 175 176 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, 177 unsigned long addr) 178 { 179 pgtable_page_dtor(pte); 180 tlb_add_flush(tlb, addr); 181 tlb_remove_page(tlb, pte); 182 } 183 184 #define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr) 185 #define pmd_free_tlb(tlb, pmdp, addr) pmd_free((tlb)->mm, pmdp) 186 187 #define tlb_migrate_finish(mm) do { } while (0) 188 189 #endif /* CONFIG_MMU */ 190 #endif 191