arch/arm/include/asm/tlb.h

   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_tlbonly(struct mmu_gather *tlb)
 102 {
 103         tlb_flush(tlb);
 104 }
 105
 106 static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
 107 {
 108         free_pages_and_swap_cache(tlb->pages, tlb->nr);
 109         tlb->nr = 0;
 110         if (tlb->pages == tlb->local)
 111                 __tlb_alloc_page(tlb);
 112 }
 113
 114 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 115 {
 116         tlb_flush_mmu_tlbonly(tlb);
 117         tlb_flush_mmu_free(tlb);
 118 }
 119
 120 static inline void
 121 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
 122 {
 123         tlb->mm = mm;
 124         tlb->fullmm = !(start | (end+1));
 125         tlb->start = start;
 126         tlb->end = end;
 127         tlb->vma = NULL;
 128         tlb->max = ARRAY_SIZE(tlb->local);
 129         tlb->pages = tlb->local;
 130         tlb->nr = 0;
 131         __tlb_alloc_page(tlb);
 132 }
 133
 134 static inline void
 135 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 136 {
 137         tlb_flush_mmu(tlb);
 138
 139         /* keep the page table cache within bounds */
 140         check_pgt_cache();
 141
 142         if (tlb->pages != tlb->local)
 143                 free_pages((unsigned long)tlb->pages, 0);
 144 }
 145
 146 /*
 147  * Memorize the range for the TLB flush.
 148  */
 149 static inline void
 150 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
 151 {
 152         tlb_add_flush(tlb, addr);
 153 }
 154
 155 /*
 156  * In the case of tlb vma handling, we can optimise these away in the
 157  * case where we're doing a full MM flush.  When we're doing a munmap,
 158  * the vmas are adjusted to only cover the region to be torn down.
 159  */
 160 static inline void
 161 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 162 {
 163         if (!tlb->fullmm) {
 164                 flush_cache_range(vma, vma->vm_start, vma->vm_end);
 165                 tlb->vma = vma;
 166                 tlb->range_start = TASK_SIZE;
 167                 tlb->range_end = 0;
 168         }
 169 }
 170
 171 static inline void
 172 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 173 {
 174         if (!tlb->fullmm)
 175                 tlb_flush(tlb);
 176 }
 177
 178 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 179 {
 180         tlb->pages[tlb->nr++] = page;
 181         VM_BUG_ON(tlb->nr > tlb->max);
 182         return tlb->max - tlb->nr;
 183 }
 184
 185 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 186 {
 187         if (!__tlb_remove_page(tlb, page))
 188                 tlb_flush_mmu(tlb);
 189 }
 190
 191 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 192         unsigned long addr)
 193 {
 194         pgtable_page_dtor(pte);
 195
 196 #ifdef CONFIG_ARM_LPAE
 197         tlb_add_flush(tlb, addr);
 198 #else
 199         /*
 200          * With the classic ARM MMU, a pte page has two corresponding pmd
 201          * entries, each covering 1MB.
 202          */
 203         addr &= PMD_MASK;
 204         tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE);
 205         tlb_add_flush(tlb, addr + SZ_1M);
 206 #endif
 207
 208         tlb_remove_page(tlb, pte);
 209 }
 210
 211 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 212                                   unsigned long addr)
 213 {
 214 #ifdef CONFIG_ARM_LPAE
 215         tlb_add_flush(tlb, addr);
 216         tlb_remove_page(tlb, virt_to_page(pmdp));
 217 #endif
 218 }
 219
 220 static inline void
 221 tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
 222 {
 223         tlb_add_flush(tlb, addr);
 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