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