arch/arm64/include/asm/tlb.h

   1 /*
   2  * Based on arch/arm/include/asm/tlb.h
   3  *
   4  * Copyright (C) 2002 Russell King
   5  * Copyright (C) 2012 ARM Ltd.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #ifndef __ASM_TLB_H
  20 #define __ASM_TLB_H
  21
  22 #include <linux/pagemap.h>
  23 #include <linux/swap.h>
  24
  25 #include <asm/pgalloc.h>
  26 #include <asm/tlbflush.h>
  27
  28 #define MMU_GATHER_BUNDLE       8
  29
  30 /*
  31  * TLB handling.  This allows us to remove pages from the page
  32  * tables, and efficiently handle the TLB issues.
  33  */
  34 struct mmu_gather {
  35         struct mm_struct        *mm;
  36         unsigned int            fullmm;
  37         struct vm_area_struct   *vma;
  38         unsigned long           range_start;
  39         unsigned long           range_end;
  40         unsigned int            nr;
  41         unsigned int            max;
  42         struct page             **pages;
  43         struct page             *local[MMU_GATHER_BUNDLE];
  44 };
  45
  46 /*
  47  * This is unnecessarily complex.  There's three ways the TLB shootdown
  48  * code is used:
  49  *  1. Unmapping a range of vmas.  See zap_page_range(), unmap_region().
  50  *     tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
  51  *     tlb->vma will be non-NULL.
  52  *  2. Unmapping all vmas.  See exit_mmap().
  53  *     tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
  54  *     tlb->vma will be non-NULL.  Additionally, page tables will be freed.
  55  *  3. Unmapping argument pages.  See shift_arg_pages().
  56  *     tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
  57  *     tlb->vma will be NULL.
  58  */
  59 static inline void tlb_flush(struct mmu_gather *tlb)
  60 {
  61         if (tlb->fullmm || !tlb->vma)
  62                 flush_tlb_mm(tlb->mm);
  63         else if (tlb->range_end > 0) {
  64                 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
  65                 tlb->range_start = TASK_SIZE;
  66                 tlb->range_end = 0;
  67         }
  68 }
  69
  70 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
  71 {
  72         if (!tlb->fullmm) {
  73                 if (addr < tlb->range_start)
  74                         tlb->range_start = addr;
  75                 if (addr + PAGE_SIZE > tlb->range_end)
  76                         tlb->range_end = addr + PAGE_SIZE;
  77         }
  78 }
  79
  80 static inline void __tlb_alloc_page(struct mmu_gather *tlb)
  81 {
  82         unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
  83
  84         if (addr) {
  85                 tlb->pages = (void *)addr;
  86                 tlb->max = PAGE_SIZE / sizeof(struct page *);
  87         }
  88 }
  89
  90 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
  91 {
  92         tlb_flush(tlb);
  93         free_pages_and_swap_cache(tlb->pages, tlb->nr);
  94         tlb->nr = 0;
  95         if (tlb->pages == tlb->local)
  96                 __tlb_alloc_page(tlb);
  97 }
  98
  99 static inline void
 100 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int fullmm)
 101 {
 102         tlb->mm = mm;
 103         tlb->fullmm = fullmm;
 104         tlb->vma = NULL;
 105         tlb->max = ARRAY_SIZE(tlb->local);
 106         tlb->pages = tlb->local;
 107         tlb->nr = 0;
 108         __tlb_alloc_page(tlb);
 109 }
 110
 111 static inline void
 112 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 113 {
 114         tlb_flush_mmu(tlb);
 115
 116         /* keep the page table cache within bounds */
 117         check_pgt_cache();
 118
 119         if (tlb->pages != tlb->local)
 120                 free_pages((unsigned long)tlb->pages, 0);
 121 }
 122
 123 /*
 124  * Memorize the range for the TLB flush.
 125  */
 126 static inline void
 127 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
 128 {
 129         tlb_add_flush(tlb, addr);
 130 }
 131
 132 /*
 133  * In the case of tlb vma handling, we can optimise these away in the
 134  * case where we're doing a full MM flush.  When we're doing a munmap,
 135  * the vmas are adjusted to only cover the region to be torn down.
 136  */
 137 static inline void
 138 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 139 {
 140         if (!tlb->fullmm) {
 141                 tlb->vma = vma;
 142                 tlb->range_start = TASK_SIZE;
 143                 tlb->range_end = 0;
 144         }
 145 }
 146
 147 static inline void
 148 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
 149 {
 150         if (!tlb->fullmm)
 151                 tlb_flush(tlb);
 152 }
 153
 154 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 155 {
 156         tlb->pages[tlb->nr++] = page;
 157         VM_BUG_ON(tlb->nr > tlb->max);
 158         return tlb->max - tlb->nr;
 159 }
 160
 161 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 162 {
 163         if (!__tlb_remove_page(tlb, page))
 164                 tlb_flush_mmu(tlb);
 165 }
 166
 167 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
 168         unsigned long addr)
 169 {
 170         pgtable_page_dtor(pte);
 171         tlb_add_flush(tlb, addr);
 172         tlb_remove_page(tlb, pte);
 173 }
 174
 175 #ifndef CONFIG_ARM64_64K_PAGES
 176 static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
 177                                   unsigned long addr)
 178 {
 179         tlb_add_flush(tlb, addr);
 180         tlb_remove_page(tlb, virt_to_page(pmdp));
 181 }
 182 #endif
 183
 184 #define pte_free_tlb(tlb, ptep, addr)   __pte_free_tlb(tlb, ptep, addr)
 185 #define pmd_free_tlb(tlb, pmdp, addr)   __pmd_free_tlb(tlb, pmdp, addr)
 186 #define pud_free_tlb(tlb, pudp, addr)   pud_free((tlb)->mm, pudp)
 187
 188 #define tlb_migrate_finish(mm)          do { } while (0)
 189
 190 #endif