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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 */
40struct 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. */
49DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
50
51/* tlb_gather_mmu
52 * Return a pointer to an initialized struct mmu_gather.
53 */
54static inline struct mmu_gather *
55tlb_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
69static inline void
70tlb_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 */
86static inline void
87tlb_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 */
102static 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 */