kernel/2.6.29.6-aldebaran-rt/include/asm-generic/tlb.h

   1 /* include/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   #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
  26 #else
  27   #define tlb_fast_mode(tlb) 1
  28 #endif
  29
  30 /* struct mmu_gather is an opaque type used by the mm code for passing around
  31  * any data needed by arch specific code for tlb_remove_page.
  32  */
  33 struct mmu_gather {
  34         struct mm_struct        *mm;
  35         unsigned int            nr;     /* set to ~0U means fast mode */
  36         unsigned int            max;    /* nr < max */
  37         unsigned int            need_flush;/* Really unmapped some ptes? */
  38         unsigned int            fullmm; /* non-zero means full mm flush */
  39 #ifdef HAVE_ARCH_MMU_GATHER
  40         struct arch_mmu_gather  arch;
  41 #endif
  42         struct page **          pages;
  43         struct page *           local[8];
  44 };
  45
  46 static inline void __tlb_alloc_pages(struct mmu_gather *tlb)
  47 {
  48         unsigned long addr = __get_free_pages(GFP_ATOMIC, 0);
  49
  50         if (addr) {
  51                 tlb->pages = (void *)addr;
  52                 tlb->max = PAGE_SIZE / sizeof(struct page *);
  53         }
  54 }
  55
  56 /* tlb_gather_mmu
  57  *      Return a pointer to an initialized struct mmu_gather.
  58  */
  59 static inline void
  60 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
  61 {
  62         tlb->mm = mm;
  63
  64         tlb->max = ARRAY_SIZE(tlb->local);
  65         tlb->pages = tlb->local;
  66
  67         if (num_online_cpus() > 1) {
  68                 tlb->nr = 0;
  69                 __tlb_alloc_pages(tlb);
  70         } else /* Use fast mode if only one CPU is online */
  71                 tlb->nr = ~0U;
  72
  73         tlb->fullmm = full_mm_flush;
  74
  75 #ifdef HAVE_ARCH_MMU_GATHER
  76         tlb->arch = ARCH_MMU_GATHER_INIT;
  77 #endif
  78 }
  79
  80 static inline void
  81 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
  82 {
  83         if (!tlb->need_flush)
  84                 return;
  85         tlb->need_flush = 0;
  86         tlb_flush(tlb);
  87         if (!tlb_fast_mode(tlb)) {
  88                 free_pages_and_swap_cache(tlb->pages, tlb->nr);
  89                 tlb->nr = 0;
  90                 if (tlb->pages == tlb->local)
  91                         __tlb_alloc_pages(tlb);
  92         }
  93 }
  94
  95 /* tlb_finish_mmu
  96  *      Called at the end of the shootdown operation to free up any resources
  97  *      that were required.
  98  */
  99 static inline void
 100 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 101 {
 102         tlb_flush_mmu(tlb, start, end);
 103
 104         /* keep the page table cache within bounds */
 105         check_pgt_cache();
 106
 107         if (tlb->pages != tlb->local)
 108                 free_pages((unsigned long)tlb->pages, 0);
 109 }
 110
 111 /* tlb_remove_page
 112  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
 113  *      handling the additional races in SMP caused by other CPUs caching valid
 114  *      mappings in their TLBs.
 115  */
 116 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 117 {
 118         tlb->need_flush = 1;
 119         if (tlb_fast_mode(tlb)) {
 120                 free_page_and_swap_cache(page);
 121                 return;
 122         }
 123         tlb->pages[tlb->nr++] = page;
 124         if (tlb->nr >= tlb->max)
 125                 tlb_flush_mmu(tlb, 0, 0);
 126 }
 127
 128 /**
 129  * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
 130  *
 131  * Record the fact that pte's were really umapped in ->need_flush, so we can
 132  * later optimise away the tlb invalidate.   This helps when userspace is
 133  * unmapping already-unmapped pages, which happens quite a lot.
 134  */
 135 #define tlb_remove_tlb_entry(tlb, ptep, address)                \
 136         do {                                                    \
 137                 tlb->need_flush = 1;                            \
 138                 __tlb_remove_tlb_entry(tlb, ptep, address);     \
 139         } while (0)
 140
 141 #define pte_free_tlb(tlb, ptep)                                 \
 142         do {                                                    \
 143                 tlb->need_flush = 1;                            \
 144                 __pte_free_tlb(tlb, ptep);                      \
 145         } while (0)
 146
 147 #ifndef __ARCH_HAS_4LEVEL_HACK
 148 #define pud_free_tlb(tlb, pudp)                                 \
 149         do {                                                    \
 150                 tlb->need_flush = 1;                            \
 151                 __pud_free_tlb(tlb, pudp);                      \
 152         } while (0)
 153 #endif
 154
 155 #define pmd_free_tlb(tlb, pmdp)                                 \
 156         do {                                                    \
 157                 tlb->need_flush = 1;                            \
 158                 __pmd_free_tlb(tlb, pmdp);                      \
 159         } while (0)
 160
 161 #define tlb_migrate_finish(mm) do {} while (0)
 162
 163 #endif /* _ASM_GENERIC__TLB_H */