Root/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  #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 */
39struct 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. */
48DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
49
50/* tlb_gather_mmu
51 * Return a pointer to an initialized struct mmu_gather.
52 */
53static inline struct mmu_gather *
54tlb_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
68static inline void
69tlb_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 */
85static inline void
86tlb_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 */
101static 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, address) \
127    do { \
128        tlb->need_flush = 1; \
129        __pte_free_tlb(tlb, ptep, address); \
130    } while (0)
131
132#ifndef __ARCH_HAS_4LEVEL_HACK
133#define pud_free_tlb(tlb, pudp, address) \
134    do { \
135        tlb->need_flush = 1; \
136        __pud_free_tlb(tlb, pudp, address); \
137    } while (0)
138#endif
139
140#define pmd_free_tlb(tlb, pmdp, address) \
141    do { \
142        tlb->need_flush = 1; \
143        __pmd_free_tlb(tlb, pmdp, address); \
144    } while (0)
145
146#define tlb_migrate_finish(mm) do {} while (0)
147
148#endif /* _ASM_GENERIC__TLB_H */
149

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