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 #define MMU_GATHER_BUNDLE 8 37 38 /* 39 * TLB handling. This allows us to remove pages from the page 40 * tables, and efficiently handle the TLB issues. 41 */ 42 struct mmu_gather { 43 struct mm_struct *mm; 44 unsigned int fullmm; 45 struct vm_area_struct *vma; 46 unsigned long start, end; 47 unsigned long range_start; 48 unsigned long range_end; 49 unsigned int nr; 50 unsigned int max; 51 struct page **pages; 52 struct page *local[MMU_GATHER_BUNDLE]; 53 }; 54 55 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); 56 57 /* 58 * This is unnecessarily complex. There's three ways the TLB shootdown 59 * code is used: 60 * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region(). 61 * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called. 62 * tlb->vma will be non-NULL. 63 * 2. Unmapping all vmas. See exit_mmap(). 64 * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called. 65 * tlb->vma will be non-NULL. Additionally, page tables will be freed. 66 * 3. Unmapping argument pages. See shift_arg_pages(). 67 * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called. 68 * tlb->vma will be NULL. 69 */ 70 static inline void tlb_flush(struct mmu_gather *tlb) 71 { 72 if (tlb->fullmm || !tlb->vma) 73 flush_tlb_mm(tlb->mm); 74 else if (tlb->range_end > 0) { 75 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end); 76 tlb->range_start = TASK_SIZE; 77 tlb->range_end = 0; 78 } 79 } 80 81 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr) 82 { 83 if (!tlb->fullmm) { 84 if (addr < tlb->range_start) 85 tlb->range_start = addr; 86 if (addr + PAGE_SIZE > tlb->range_end) 87 tlb->range_end = addr + PAGE_SIZE; 88 } 89 } 90 91 static inline void __tlb_alloc_page(struct mmu_gather *tlb) 92 { 93 unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 94 95 if (addr) { 96 tlb->pages = (void *)addr; 97 tlb->max = PAGE_SIZE / sizeof(struct page *); 98 } 99 } 100 101 static inline void tlb_flush_mmu(struct mmu_gather *tlb) 102 { 103 tlb_flush(tlb); 104 free_pages_and_swap_cache(tlb->pages, tlb->nr); 105 tlb->nr = 0; 106 if (tlb->pages == tlb->local) 107 __tlb_alloc_page(tlb); 108 } 109 110 static inline void 111 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end) 112 { 113 tlb->mm = mm; 114 tlb->fullmm = !(start | (end+1)); 115 tlb->start = start; 116 tlb->end = end; 117 tlb->vma = NULL; 118 tlb->max = ARRAY_SIZE(tlb->local); 119 tlb->pages = tlb->local; 120 tlb->nr = 0; 121 __tlb_alloc_page(tlb); 122 } 123 124 static inline void 125 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 126 { 127 tlb_flush_mmu(tlb); 128 129 /* keep the page table cache within bounds */ 130 check_pgt_cache(); 131 132 if (tlb->pages != tlb->local) 133 free_pages((unsigned long)tlb->pages, 0); 134 } 135 136 /* 137 * Memorize the range for the TLB flush. 138 */ 139 static inline void 140 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr) 141 { 142 tlb_add_flush(tlb, addr); 143 } 144 145 /* 146 * In the case of tlb vma handling, we can optimise these away in the 147 * case where we're doing a full MM flush. When we're doing a munmap, 148 * the vmas are adjusted to only cover the region to be torn down. 149 */ 150 static inline void 151 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) 152 { 153 if (!tlb->fullmm) { 154 flush_cache_range(vma, vma->vm_start, vma->vm_end); 155 tlb->vma = vma; 156 tlb->range_start = TASK_SIZE; 157 tlb->range_end = 0; 158 } 159 } 160 161 static inline void 162 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) 163 { 164 if (!tlb->fullmm) 165 tlb_flush(tlb); 166 } 167 168 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 169 { 170 tlb->pages[tlb->nr++] = page; 171 VM_BUG_ON(tlb->nr > tlb->max); 172 return tlb->max - tlb->nr; 173 } 174 175 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) 176 { 177 if (!__tlb_remove_page(tlb, page)) 178 tlb_flush_mmu(tlb); 179 } 180 181 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, 182 unsigned long addr) 183 { 184 pgtable_page_dtor(pte); 185 186 #ifdef CONFIG_ARM_LPAE 187 tlb_add_flush(tlb, addr); 188 #else 189 /* 190 * With the classic ARM MMU, a pte page has two corresponding pmd 191 * entries, each covering 1MB. 192 */ 193 addr &= PMD_MASK; 194 tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE); 195 tlb_add_flush(tlb, addr + SZ_1M); 196 #endif 197 198 tlb_remove_page(tlb, pte); 199 } 200 201 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, 202 unsigned long addr) 203 { 204 #ifdef CONFIG_ARM_LPAE 205 tlb_add_flush(tlb, addr); 206 tlb_remove_page(tlb, virt_to_page(pmdp)); 207 #endif 208 } 209 210 static inline void 211 tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr) 212 { 213 tlb_add_flush(tlb, addr); 214 } 215 216 #define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr) 217 #define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr) 218 #define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp) 219 220 #define tlb_migrate_finish(mm) do { } while (0) 221 222 #endif /* CONFIG_MMU */ 223 #endif 224