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