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(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