1 /* include/asm-generic/tlb.h
3 * Generic TLB shootdown code
5 * Copyright 2001 Red Hat, Inc.
6 * Based on code from mm/memory.c Copyright Linus Torvalds and others.
8 * Copyright 2011 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
10 * 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.
15 #ifndef _ASM_GENERIC__TLB_H
16 #define _ASM_GENERIC__TLB_H
18 #include <linux/swap.h>
19 #include <asm/pgalloc.h>
20 #include <asm/tlbflush.h>
23 * For UP we don't need to worry about TLB flush
24 * and page free order so much..
27 #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
29 #define tlb_fast_mode(tlb) 1
33 * If we can't allocate a page to make a big batch of page pointers
34 * to work on, then just handle a few from the on-stack structure.
36 #define MMU_GATHER_BUNDLE 8
38 /* struct mmu_gather is an opaque type used by the mm code for passing around
39 * any data needed by arch specific code for tlb_remove_page.
43 unsigned int nr; /* set to ~0U means fast mode */
44 unsigned int max; /* nr < max */
45 unsigned int need_flush;/* Really unmapped some ptes? */
46 unsigned int fullmm; /* non-zero means full mm flush */
47 #ifdef HAVE_ARCH_MMU_GATHER
48 struct arch_mmu_gather arch;
51 struct page *local[MMU_GATHER_BUNDLE];
54 static inline void __tlb_alloc_page(struct mmu_gather *tlb)
56 unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
59 tlb->pages = (void *)addr;
60 tlb->max = PAGE_SIZE / sizeof(struct page *);
65 * Called to initialize an (on-stack) mmu_gather structure for page-table
66 * tear-down from @mm. The @fullmm argument is used when @mm is without
67 * users and we're going to destroy the full address space (exit/execve).
70 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm)
74 tlb->max = ARRAY_SIZE(tlb->local);
75 tlb->pages = tlb->local;
77 if (num_online_cpus() > 1) {
79 __tlb_alloc_page(tlb);
80 } else /* Use fast mode if only one CPU is online */
85 #ifdef HAVE_ARCH_MMU_GATHER
86 tlb->arch = ARCH_MMU_GATHER_INIT;
91 tlb_flush_mmu(struct mmu_gather *tlb)
97 if (!tlb_fast_mode(tlb)) {
98 free_pages_and_swap_cache(tlb->pages, tlb->nr);
101 * If we are using the local on-stack array of pages for MMU
102 * gather, try allocating an off-stack array again as we have
103 * recently freed pages.
105 if (tlb->pages == tlb->local)
106 __tlb_alloc_page(tlb);
111 * Called at the end of the shootdown operation to free up any resources
112 * that were required.
115 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
119 /* keep the page table cache within bounds */
122 if (tlb->pages != tlb->local)
123 free_pages((unsigned long)tlb->pages, 0);
127 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
128 * handling the additional races in SMP caused by other CPUs caching valid
129 * mappings in their TLBs. Returns the number of free page slots left.
130 * When out of page slots we must call tlb_flush_mmu().
132 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
135 if (tlb_fast_mode(tlb)) {
136 free_page_and_swap_cache(page);
137 return 1; /* avoid calling tlb_flush_mmu() */
139 tlb->pages[tlb->nr++] = page;
140 VM_BUG_ON(tlb->nr > tlb->max);
142 return tlb->max - tlb->nr;
146 * Similar to __tlb_remove_page but will call tlb_flush_mmu() itself when
149 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
151 if (!__tlb_remove_page(tlb, page))
156 * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
158 * Record the fact that pte's were really umapped in ->need_flush, so we can
159 * later optimise away the tlb invalidate. This helps when userspace is
160 * unmapping already-unmapped pages, which happens quite a lot.
162 #define tlb_remove_tlb_entry(tlb, ptep, address) \
164 tlb->need_flush = 1; \
165 __tlb_remove_tlb_entry(tlb, ptep, address); \
168 #define pte_free_tlb(tlb, ptep, address) \
170 tlb->need_flush = 1; \
171 __pte_free_tlb(tlb, ptep, address); \
174 #ifndef __ARCH_HAS_4LEVEL_HACK
175 #define pud_free_tlb(tlb, pudp, address) \
177 tlb->need_flush = 1; \
178 __pud_free_tlb(tlb, pudp, address); \
182 #define pmd_free_tlb(tlb, pmdp, address) \
184 tlb->need_flush = 1; \
185 __pmd_free_tlb(tlb, pmdp, address); \
188 #define tlb_migrate_finish(mm) do {} while (0)
190 #endif /* _ASM_GENERIC__TLB_H */