include/asm-generic/tlb.h

   1 /* asm-generic/tlb.h
   2  *
   3  *      Generic TLB shootdown code
   4  *
   5  * Copyright 2001 Red Hat, Inc.
   6  * Based on code from mm/memory.c Copyright Linus Torvalds and others.
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the License, or (at your option) any later version.
  12  */
  13 #ifndef _ASM_GENERIC__TLB_H
  14 #define _ASM_GENERIC__TLB_H
  15
  16 #include <linux/swap.h>
  17 #include <asm/pgalloc.h>
  18 #include <asm/tlbflush.h>
  19
  20 /*
  21  * For UP we don't need to worry about TLB flush
  22  * and page free order so much..
  23  */
  24 #ifdef CONFIG_SMP
  25   #ifdef ARCH_FREE_PTR_NR
  26     #define FREE_PTR_NR   ARCH_FREE_PTR_NR
  27   #else
  28     #define FREE_PTE_NR 506
  29   #endif
  30   #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
  31 #else
  32   #define FREE_PTE_NR   1
  33   #define tlb_fast_mode(tlb) 1
  34 #endif
  35
  36 /* struct mmu_gather is an opaque type used by the mm code for passing around
  37  * any data needed by arch specific code for tlb_remove_page.
  38  */
  39 struct mmu_gather {
  40         struct mm_struct        *mm;
  41         unsigned int            nr;     /* set to ~0U means fast mode */
  42         unsigned int            need_flush;/* Really unmapped some ptes? */
  43         unsigned int            fullmm; /* non-zero means full mm flush */
  44         struct page *           pages[FREE_PTE_NR];
  45 };
  46
  47 /* Users of the generic TLB shootdown code must declare this storage space. */
  48 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
  49
  50 /* tlb_gather_mmu
  51  *      Return a pointer to an initialized struct mmu_gather.
  52  */
  53 static inline struct mmu_gather *
  54 tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
  55 {
  56         struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
  57
  58         tlb->mm = mm;
  59
  60         /* Use fast mode if only one CPU is online */
  61         tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
  62
  63         tlb->fullmm = full_mm_flush;
  64
  65         return tlb;
  66 }
  67
  68 static inline void
  69 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
  70 {
  71         if (!tlb->need_flush)
  72                 return;
  73         tlb->need_flush = 0;
  74         tlb_flush(tlb);
  75         if (!tlb_fast_mode(tlb)) {
  76                 free_pages_and_swap_cache(tlb->pages, tlb->nr);
  77                 tlb->nr = 0;
  78         }
  79 }
  80
  81 /* tlb_finish_mmu
  82  *      Called at the end of the shootdown operation to free up any resources
  83  *      that were required.
  84  */
  85 static inline void
  86 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
  87 {
  88         tlb_flush_mmu(tlb, start, end);
  89
  90         /* keep the page table cache within bounds */
  91         check_pgt_cache();
  92
  93         put_cpu_var(mmu_gathers);
  94 }
  95
  96 /* tlb_remove_page
  97  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
  98  *      handling the additional races in SMP caused by other CPUs caching valid
  99  *      mappings in their TLBs.
 100  */
 101 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 102 {
 103         tlb->need_flush = 1;
 104         if (tlb_fast_mode(tlb)) {
 105                 free_page_and_swap_cache(page);
 106                 return;
 107         }
 108         tlb->pages[tlb->nr++] = page;
 109         if (tlb->nr >= FREE_PTE_NR)
 110                 tlb_flush_mmu(tlb, 0, 0);
 111 }
 112
 113 /**
 114  * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
 115  *
 116  * Record the fact that pte's were really umapped in ->need_flush, so we can
 117  * later optimise away the tlb invalidate.   This helps when userspace is
 118  * unmapping already-unmapped pages, which happens quite a lot.
 119  */
 120 #define tlb_remove_tlb_entry(tlb, ptep, address)                \
 121         do {                                                    \
 122                 tlb->need_flush = 1;                            \
 123                 __tlb_remove_tlb_entry(tlb, ptep, address);     \
 124         } while (0)
 125
 126 #define pte_free_tlb(tlb, ptep)                                 \
 127         do {                                                    \
 128                 tlb->need_flush = 1;                            \
 129                 __pte_free_tlb(tlb, ptep);                      \
 130         } while (0)
 131
 132 #ifndef __ARCH_HAS_4LEVEL_HACK
 133 #define pud_free_tlb(tlb, pudp)                                 \
 134         do {                                                    \
 135                 tlb->need_flush = 1;                            \
 136                 __pud_free_tlb(tlb, pudp);                      \
 137         } while (0)
 138 #endif
 139
 140 #define pmd_free_tlb(tlb, pmdp)                                 \
 141         do {                                                    \
 142                 tlb->need_flush = 1;                            \
 143                 __pmd_free_tlb(tlb, pmdp);                      \
 144         } while (0)
 145
 146 #define tlb_migrate_finish(mm) do {} while (0)
 147
 148 #endif /* _ASM_GENERIC__TLB_H */