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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
Michal Hocko53a59fc2013-01-04 15:35:12 -080081/*
82 * Limit the maximum number of mmu_gather batches to reduce a risk of soft
83 * lockups for non-preemptible kernels on huge machines when a lot of memory
84 * is zapped during unmapping.
85 * 10K pages freed at once should be safe even without a preemption point.
86 */
87#define MAX_GATHER_BATCH_COUNT (10000UL/MAX_GATHER_BATCH)
88
Linus Torvalds1da177e2005-04-16 15:20:36 -070089/* struct mmu_gather is an opaque type used by the mm code for passing around
Hugh Dickins15a23ff2005-10-29 18:16:01 -070090 * any data needed by arch specific code for tlb_remove_page.
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 */
92struct mmu_gather {
93 struct mm_struct *mm;
Peter Zijlstra26723912011-05-24 17:12:00 -070094#ifdef CONFIG_HAVE_RCU_TABLE_FREE
95 struct mmu_table_batch *batch;
96#endif
Alex Shi597e1c32012-06-28 09:02:21 +080097 unsigned long start;
98 unsigned long end;
Peter Zijlstrae3032972011-05-24 17:12:01 -070099 unsigned int need_flush : 1, /* Did free PTEs */
Dave Hansen1de14c32013-04-12 16:23:54 -0700100 /* we are in the middle of an operation to clear
101 * a full mm and can make some optimizations */
Peter Zijlstra29eb7782013-06-05 12:26:50 +0200102 fullmm : 1,
Dave Hansen1de14c32013-04-12 16:23:54 -0700103 /* we have performed an operation which
104 * requires a complete flush of the tlb */
105 need_flush_all : 1;
Peter Zijlstrae3032972011-05-24 17:12:01 -0700106
107 struct mmu_gather_batch *active;
108 struct mmu_gather_batch local;
109 struct page *__pages[MMU_GATHER_BUNDLE];
Michal Hocko53a59fc2013-01-04 15:35:12 -0800110 unsigned int batch_count;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111};
112
Peter Zijlstra9547d012011-05-24 17:12:14 -0700113#define HAVE_GENERIC_MMU_GATHER
114
Linus Torvalds2b047252013-08-15 11:42:25 -0700115void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end);
Peter Zijlstra9547d012011-05-24 17:12:14 -0700116void tlb_flush_mmu(struct mmu_gather *tlb);
Alex Shic4211f42012-06-28 09:02:19 +0800117void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start,
118 unsigned long end);
Peter Zijlstra9547d012011-05-24 17:12:14 -0700119int __tlb_remove_page(struct mmu_gather *tlb, struct page *page);
Peter Zijlstrad16dfc52011-05-24 17:11:45 -0700120
121/* tlb_remove_page
122 * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when
123 * required.
124 */
125static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
126{
127 if (!__tlb_remove_page(tlb, page))
128 tlb_flush_mmu(tlb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129}
130
131/**
132 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
133 *
134 * Record the fact that pte's were really umapped in ->need_flush, so we can
135 * later optimise away the tlb invalidate. This helps when userspace is
136 * unmapping already-unmapped pages, which happens quite a lot.
137 */
138#define tlb_remove_tlb_entry(tlb, ptep, address) \
139 do { \
140 tlb->need_flush = 1; \
141 __tlb_remove_tlb_entry(tlb, ptep, address); \
142 } while (0)
143
Shaohua Lif21760b2012-01-12 17:19:16 -0800144/**
145 * tlb_remove_pmd_tlb_entry - remember a pmd mapping for later tlb invalidation
146 * This is a nop so far, because only x86 needs it.
147 */
148#ifndef __tlb_remove_pmd_tlb_entry
149#define __tlb_remove_pmd_tlb_entry(tlb, pmdp, address) do {} while (0)
150#endif
151
152#define tlb_remove_pmd_tlb_entry(tlb, pmdp, address) \
153 do { \
154 tlb->need_flush = 1; \
155 __tlb_remove_pmd_tlb_entry(tlb, pmdp, address); \
156 } while (0)
157
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000158#define pte_free_tlb(tlb, ptep, address) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700159 do { \
160 tlb->need_flush = 1; \
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000161 __pte_free_tlb(tlb, ptep, address); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 } while (0)
163
164#ifndef __ARCH_HAS_4LEVEL_HACK
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000165#define pud_free_tlb(tlb, pudp, address) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 do { \
167 tlb->need_flush = 1; \
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000168 __pud_free_tlb(tlb, pudp, address); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 } while (0)
170#endif
171
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000172#define pmd_free_tlb(tlb, pmdp, address) \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 do { \
174 tlb->need_flush = 1; \
Benjamin Herrenschmidt9e1b32c2009-07-22 15:44:28 +1000175 __pmd_free_tlb(tlb, pmdp, address); \
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 } while (0)
177
178#define tlb_migrate_finish(mm) do {} while (0)
179
180#endif /* _ASM_GENERIC__TLB_H */