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 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
  39 static inline void __tlb_remove_table(void *_table)
  40 {
  41         free_page_and_swap_cache((struct page *)_table);
  42 }
  43
  44 struct mmu_table_batch {
  45         struct rcu_head         rcu;
  46         unsigned int            nr;
  47         void                    *tables[0];
  48 };
  49
  50 #define MAX_TABLE_BATCH         \
  51         ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
  52
  53 extern void tlb_table_flush(struct mmu_gather *tlb);
  54 extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
  55
  56 #define tlb_remove_entry(tlb, entry)    tlb_remove_table(tlb, entry)
  57 #else
  58 #define tlb_remove_entry(tlb, entry)    tlb_remove_page(tlb, entry)
  59 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
  60
  61 /*
  62  * TLB handling.  This allows us to remove pages from the page
  63  * tables, and efficiently handle the TLB issues.
  64  */
  65 struct mmu_gather {
  66         struct mm_struct        *mm;
  67 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
  68         struct mmu_table_batch  *batch;
  69         unsigned int            need_flush;
  70 #endif
  71         unsigned int            fullmm;
  72         struct vm_area_struct   *vma;
  73         unsigned long           start, end;
  74         unsigned long           range_start;
  75         unsigned long           range_end;
  76         unsigned int            nr;
  77         unsigned int            max;
  78         struct page             **pages;
  79         struct page             *local[MMU_GATHER_BUNDLE];
  80 };
  81
  82 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
  83
  84 /*
  85  * This is unnecessarily complex.  There's three ways the TLB shootdown
  86  * code is used:
  87  *  1. Unmapping a range of vmas.  See zap_page_range(), unmap_region().
  88  *     tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
  89  *     tlb->vma will be non-NULL.
  90  *  2. Unmapping all vmas.  See exit_mmap().
  91  *     tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
  92  *     tlb->vma will be non-NULL.  Additionally, page tables will be freed.
  93  *  3. Unmapping argument pages.  See shift_arg_pages().
  94  *     tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
  95  *     tlb->vma will be NULL.
  96  */
  97 static inline void tlb_flush(struct mmu_gather *tlb)
  98 {
  99         if (tlb->fullmm || !tlb->vma)
 100                 flush_tlb_mm(tlb->mm);
 101         else if (tlb->range_end > 0) {
 102                 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
 103                 tlb->range_start = TASK_SIZE;
 104                 tlb->range_end = 0;
 105         }
 106 }
 107
 108 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
 109 {
 110         if (!tlb->fullmm) {
 111                 if (addr < tlb->range_start)
 112                         tlb->range_start = addr;
 113                 if (addr + PAGE_SIZE > tlb->range_end)
 114                         tlb->range_end = addr + PAGE_SIZE;
 115         }
 116 }
 117
 118 static inline void __tlb_alloc_page(struct mmu_gather *tlb)
 119 {
 120         unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
 121
 122         if (addr) {
 123                 tlb->pages = (void *)addr;
 124                 tlb->max = PAGE_SIZE / sizeof(struct page *);
 125         }
 126 }
 127
 128 static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
 129 {
 130         tlb_flush(tlb);
 131 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 132         tlb_table_flush(tlb);
 133 #endif
 134 }
 135
 136 static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
 137 {
 138         free_pages_and_swap_cache(tlb->pages, tlb->nr);
 139         tlb->nr = 0;
 140         if (tlb->pages == tlb->local)
 141                 __tlb_alloc_page(tlb);
 142 }
 143
 144 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 145 {
 146         tlb_flush_mmu_tlbonly(tlb);
 147         tlb_flush_mmu_free(tlb);
 148 }
 149
 150 static inline void
 151 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
 152 {
 153         tlb->mm = mm;
 154         tlb->fullmm = !(start | (end+1));
 155         tlb->start = start;
 156         tlb->end = end;
 157         tlb->vma = NULL;
 158         tlb->max = ARRAY_SIZE(tlb->local);
 159         tlb->pages = tlb->local;
 160         tlb->nr = 0;
 161         __tlb_alloc_page(tlb);
 162
 163 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 164         tlb->batch = NULL;
 165 #endif
 166 }
 167
 168 static inline void
 169 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 170 {
 171         tlb_flush_mmu(tlb);
 172
 173         /* keep the page table cache within bounds */
 174         check_pgt_cache();
 175
 176         if (tlb->pages != tlb->local)
 177                 free_pages((unsigned long)tlb->pages, 0);
 178 }
 179
 180 /*
 181  * Memorize the range for the TLB flush.
 182  */
 183 static inline void
 184 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
 185 {
 186         tlb_add_flush(tlb, addr);
 187 }
 188
 189 /*
 190  * In the case of tlb vma handling, we can optimise these away in the
 191  * case where we're doing a full MM flush.  When we're doing a munmap,
 192  * the vmas are adjusted to only cover the region to be torn down.
 193  */
 194 static inline void
 195 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 196 {
 197         if (!tlb->fullmm) {
 198                 flush_cache_range(vma, vma->vm_start, vma->vm_end);
 199                 tlb->vma = vma;
 200                 tlb->range_start = TASK_SIZE;
 201                 tlb->range_end = 0;
 202         }
 203 }
 204
 205 static inline void
 206 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 207 {
 208         if (!tlb->fullmm)
 209                 tlb_flush(tlb);
 210 }
 211
 212 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 213 {
 214         tlb->pages[tlb->nr++] = page;
 215         VM_BUG_ON(tlb->nr > tlb->max);
 216         return tlb->max - tlb->nr;
 217 }
 218
 219 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 220 {
 221         if (!__tlb_remove_page(tlb, page))
 222                 tlb_flush_mmu(tlb);
 223 }
 224
 225 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 226         unsigned long addr)
 227 {
 228         pgtable_page_dtor(pte);
 229
 230 #ifdef CONFIG_ARM_LPAE
 231         tlb_add_flush(tlb, addr);
 232 #else
 233         /*
 234          * With the classic ARM MMU, a pte page has two corresponding pmd
 235          * entries, each covering 1MB.
 236          */
 237         addr &= PMD_MASK;
 238         tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE);
 239         tlb_add_flush(tlb, addr + SZ_1M);
 240 #endif
 241
 242         tlb_remove_entry(tlb, pte);
 243 }
 244
 245 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 246                                   unsigned long addr)
 247 {
 248 #ifdef CONFIG_ARM_LPAE
 249         tlb_add_flush(tlb, addr);
 250         tlb_remove_entry(tlb, virt_to_page(pmdp));
 251 #endif
 252 }
 253
 254 static inline void
 255 tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
 256 {
 257         tlb_add_flush(tlb, addr);
 258 }
 259
 260 #define pte_free_tlb(tlb, ptep, addr)   __pte_free_tlb(tlb, ptep, addr)
 261 #define pmd_free_tlb(tlb, pmdp, addr)   __pmd_free_tlb(tlb, pmdp, addr)
 262 #define pud_free_tlb(tlb, pudp, addr)   pud_free((tlb)->mm, pudp)
 263
 264 #define tlb_migrate_finish(mm)          do { } while (0)
 265
 266 #endif /* CONFIG_MMU */
 267 #endif