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 #else 45 #define tlb_fast_mode(tlb) 1 46 #endif 47 48 #define MMU_GATHER_BUNDLE 8 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 unsigned int max; 62 struct page **pages; 63 struct page *local[MMU_GATHER_BUNDLE]; 64 }; 65 66 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers); 67 68 /* 69 * This is unnecessarily complex. There's three ways the TLB shootdown 70 * code is used: 71 * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region(). 72 * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called. 73 * tlb->vma will be non-NULL. 74 * 2. Unmapping all vmas. See exit_mmap(). 75 * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called. 76 * tlb->vma will be non-NULL. Additionally, page tables will be freed. 77 * 3. Unmapping argument pages. See shift_arg_pages(). 78 * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called. 79 * tlb->vma will be NULL. 80 */ 81 static inline void tlb_flush(struct mmu_gather *tlb) 82 { 83 if (tlb->fullmm || !tlb->vma) 84 flush_tlb_mm(tlb->mm); 85 else if (tlb->range_end > 0) { 86 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end); 87 tlb->range_start = TASK_SIZE; 88 tlb->range_end = 0; 89 } 90 } 91 92 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr) 93 { 94 if (!tlb->fullmm) { 95 if (addr < tlb->range_start) 96 tlb->range_start = addr; 97 if (addr + PAGE_SIZE > tlb->range_end) 98 tlb->range_end = addr + PAGE_SIZE; 99 } 100 } 101 102 static inline void __tlb_alloc_page(struct mmu_gather *tlb) 103 { 104 unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 105 106 if (addr) { 107 tlb->pages = (void *)addr; 108 tlb->max = PAGE_SIZE / sizeof(struct page *); 109 } 110 } 111 112 static inline void tlb_flush_mmu(struct mmu_gather *tlb) 113 { 114 tlb_flush(tlb); 115 if (!tlb_fast_mode(tlb)) { 116 free_pages_and_swap_cache(tlb->pages, tlb->nr); 117 tlb->nr = 0; 118 if (tlb->pages == tlb->local) 119 __tlb_alloc_page(tlb); 120 } 121 } 122 123 static inline void 124 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int fullmm) 125 { 126 tlb->mm = mm; 127 tlb->fullmm = fullmm; 128 tlb->vma = NULL; 129 tlb->max = ARRAY_SIZE(tlb->local); 130 tlb->pages = tlb->local; 131 tlb->nr = 0; 132 __tlb_alloc_page(tlb); 133 } 134 135 static inline void 136 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 137 { 138 tlb_flush_mmu(tlb); 139 140 /* keep the page table cache within bounds */ 141 check_pgt_cache(); 142 143 if (tlb->pages != tlb->local) 144 free_pages((unsigned long)tlb->pages, 0); 145 } 146 147 /* 148 * Memorize the range for the TLB flush. 149 */ 150 static inline void 151 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr) 152 { 153 tlb_add_flush(tlb, addr); 154 } 155 156 /* 157 * In the case of tlb vma handling, we can optimise these away in the 158 * case where we're doing a full MM flush. When we're doing a munmap, 159 * the vmas are adjusted to only cover the region to be torn down. 160 */ 161 static inline void 162 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) 163 { 164 if (!tlb->fullmm) { 165 flush_cache_range(vma, vma->vm_start, vma->vm_end); 166 tlb->vma = vma; 167 tlb->range_start = TASK_SIZE; 168 tlb->range_end = 0; 169 } 170 } 171 172 static inline void 173 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma) 174 { 175 if (!tlb->fullmm) 176 tlb_flush(tlb); 177 } 178 179 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 180 { 181 if (tlb_fast_mode(tlb)) { 182 free_page_and_swap_cache(page); 183 return 1; /* avoid calling tlb_flush_mmu */ 184 } 185 186 tlb->pages[tlb->nr++] = page; 187 VM_BUG_ON(tlb->nr > tlb->max); 188 return tlb->max - tlb->nr; 189 } 190 191 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page) 192 { 193 if (!__tlb_remove_page(tlb, page)) 194 tlb_flush_mmu(tlb); 195 } 196 197 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte, 198 unsigned long addr) 199 { 200 pgtable_page_dtor(pte); 201 202 #ifdef CONFIG_ARM_LPAE 203 tlb_add_flush(tlb, addr); 204 #else 205 /* 206 * With the classic ARM MMU, a pte page has two corresponding pmd 207 * entries, each covering 1MB. 208 */ 209 addr &= PMD_MASK; 210 tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE); 211 tlb_add_flush(tlb, addr + SZ_1M); 212 #endif 213 214 tlb_remove_page(tlb, pte); 215 } 216 217 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp, 218 unsigned long addr) 219 { 220 #ifdef CONFIG_ARM_LPAE 221 tlb_add_flush(tlb, addr); 222 tlb_remove_page(tlb, virt_to_page(pmdp)); 223 #endif 224 } 225 226 #define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr) 227 #define pmd_free_tlb(tlb, pmdp, addr) __pmd_free_tlb(tlb, pmdp, addr) 228 #define pud_free_tlb(tlb, pudp, addr) pud_free((tlb)->mm, pudp) 229 230 #define tlb_migrate_finish(mm) do { } while (0) 231 232 #endif /* CONFIG_MMU */ 233 #endif 234