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Uwe Zeisbergerf30c2262006-10-03 23:01:26 +02001/* include/asm-generic/tlb.h
Linus Torvalds1da177e2005-04-16 15:20:36 -07002 *
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 *
Peter Zijlstrad16dfc52011-05-24 17:11:45 -07008 * Copyright 2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
9 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15#ifndef _ASM_GENERIC__TLB_H
16#define _ASM_GENERIC__TLB_H
17
Linus Torvalds1da177e2005-04-16 15:20:36 -070018#include <linux/swap.h>
Ingo Molnar62152d02008-01-31 22:05:48 +010019#include <asm/pgalloc.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <asm/tlbflush.h>
21
Peter Zijlstra26723912011-05-24 17:12:00 -070022#ifdef CONFIG_HAVE_RCU_TABLE_FREE
23/*
24 * Semi RCU freeing of the page directories.
25 *
26 * This is needed by some architectures to implement software pagetable walkers.
27 *
28 * gup_fast() and other software pagetable walkers do a lockless page-table
29 * walk and therefore needs some synchronization with the freeing of the page
30 * directories. The chosen means to accomplish that is by disabling IRQs over
31 * the walk.
32 *
33 * Architectures that use IPIs to flush TLBs will then automagically DTRT,
34 * since we unlink the page, flush TLBs, free the page. Since the disabling of
35 * IRQs delays the completion of the TLB flush we can never observe an already
36 * freed page.
37 *
38 * Architectures that do not have this (PPC) need to delay the freeing by some
39 * other means, this is that means.
40 *
41 * What we do is batch the freed directory pages (tables) and RCU free them.
42 * We use the sched RCU variant, as that guarantees that IRQ/preempt disabling
43 * holds off grace periods.
44 *
45 * However, in order to batch these pages we need to allocate storage, this
46 * allocation is deep inside the MM code and can thus easily fail on memory
47 * pressure. To guarantee progress we fall back to single table freeing, see
48 * the implementation of tlb_remove_table_one().
49 *
50 */
51struct mmu_table_batch {
52 struct rcu_head rcu;
53 unsigned int nr;
54 void *tables[0];
55};
56
57#define MAX_TABLE_BATCH \
58 ((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
59
60extern void tlb_table_flush(struct mmu_gather *tlb);
61extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
62
63#endif
64
Peter Zijlstrad16dfc52011-05-24 17:11:45 -070065/*
66 * If we can't allocate a page to make a big batch of page pointers
67 * to work on, then just handle a few from the on-stack structure.
68 */
69#define MMU_GATHER_BUNDLE 8
70
Peter Zijlstrae3032972011-05-24 17:12:01 -070071struct mmu_gather_batch {
72 struct mmu_gather_batch *next;
73 unsigned int nr;
74 unsigned int max;
75 struct page *pages[0];
76};
77
78#define MAX_GATHER_BATCH \
79 ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *))
80
Linus Torvalds1da177e2005-04-16 15:20:36 -070081/* struct mmu_gather is an opaque type used by the mm code for passing around
Hugh Dickins15a23ff2005-10-29 18:16:01 -070082 * any data needed by arch specific code for tlb_remove_page.
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 */
84struct mmu_gather {
85 struct mm_struct *mm;
Peter Zijlstra26723912011-05-24 17:12:00 -070086#ifdef CONFIG_HAVE_RCU_TABLE_FREE
87 struct mmu_table_batch *batch;
88#endif
Alex Shi597e1c32012-06-28 09:02:21 +080089 unsigned long start;
90 unsigned long end;
Peter Zijlstrae3032972011-05-24 17:12:01 -070091 unsigned int need_flush : 1, /* Did free PTEs */
92 fast_mode : 1; /* No batching */
93
94 unsigned int fullmm;
95
96 struct mmu_gather_batch *active;
97 struct mmu_gather_batch local;
98 struct page *__pages[MMU_GATHER_BUNDLE];
Linus Torvalds1da177e2005-04-16 15:20:36 -070099};
100
Peter Zijlstra9547d012011-05-24 17:12:14 -0700101#define HAVE_GENERIC_MMU_GATHER
102
103static inline int tlb_fast_mode(struct mmu_gather *tlb)
104{
Peter Zijlstrae3032972011-05-24 17:12:01 -0700105#ifdef CONFIG_SMP
Peter Zijlstra9547d012011-05-24 17:12:14 -0700106 return tlb->fast_mode;
Peter Zijlstrae3032972011-05-24 17:12:01 -0700107#else
Peter Zijlstra9547d012011-05-24 17:12:14 -0700108 /*
109 * For UP we don't need to worry about TLB flush
110 * and page free order so much..
111 */
Peter Zijlstrae3032972011-05-24 17:12:01 -0700112 return 1;
Peter Zijlstrad16dfc52011-05-24 17:11:45 -0700113#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114}
115
Peter Zijlstra9547d012011-05-24 17:12:14 -0700116void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm);
117void tlb_flush_mmu(struct mmu_gather *tlb);
Alex Shic4211f42012-06-28 09:02:19 +0800118void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start,
119 unsigned long end);
Peter Zijlstra9547d012011-05-24 17:12:14 -0700120int __tlb_remove_page(struct mmu_gather *tlb, struct page *page);
Peter Zijlstrad16dfc52011-05-24 17:11:45 -0700121
122/* tlb_remove_page
123 * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when
124 * required.
125 */
126static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
127{
128 if (!__tlb_remove_page(tlb, page))
129 tlb_flush_mmu(tlb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130}
131
132/**
133 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
134 *
135 * Record the fact that pte's were really umapped in ->need_flush, so we can
136 * later optimise away the tlb invalidate. This helps when userspace is
137 * unmapping already-unmapped pages, which happens quite a lot.
138 */
139#define tlb_remove_tlb_entry(tlb, ptep, address) \
140 do { \
141 tlb->need_flush = 1; \
142 __tlb_remove_tlb_entry(tlb, ptep, address); \
143 } while (0)
144
Shaohua Lif21760b2012-01-12 17:19:16 -0800145/**
146 * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation
147 * This is a nop so far, because only x86 needs it.
148 */
149#ifndef __tlb_remove_pmd_tlb_entry
150#define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0)
151#endif
152
153#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \
154 do { \
155 tlb->need_flush = 1; \
156 __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \
157 } while (0)
158
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000159#define pte_free_tlb(tlb, ptep, address) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 do { \
161 tlb->need_flush = 1; \
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000162 __pte_free_tlb(tlb, ptep, address); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 } while (0)
164
165#ifndef __ARCH_HAS_4LEVEL_HACK
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000166#define pud_free_tlb(tlb, pudp, address) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 do { \
168 tlb->need_flush = 1; \
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000169 __pud_free_tlb(tlb, pudp, address); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170 } while (0)
171#endif
172
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000173#define pmd_free_tlb(tlb, pmdp, address) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174 do { \
175 tlb->need_flush = 1; \
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000176 __pmd_free_tlb(tlb, pmdp, address); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 } while (0)
178
179#define tlb_migrate_finish(mm) do {} while (0)
180
181#endif /* _ASM_GENERIC__TLB_H */