2 * arch/arm/include/asm/tlb.h
4 * Copyright (C) 2002 Russell King
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * Experimentation shows that on a StrongARM, it appears to be faster
11 * to use the "invalidate whole tlb" rather than "invalidate single
14 * This appears true for both the process fork+exit case, as well as
15 * the munmap-large-area case.
17 #ifndef __ASMARM_TLB_H
18 #define __ASMARM_TLB_H
20 #include <asm/cacheflush.h>
24 #include <linux/pagemap.h>
26 #define tlb_flush(tlb) ((void) tlb)
28 #include <asm-generic/tlb.h>
30 #else /* !CONFIG_MMU */
32 #include <linux/swap.h>
33 #include <asm/pgalloc.h>
34 #include <asm/tlbflush.h>
37 * We need to delay page freeing for SMP as other CPUs can access pages
38 * which have been removed but not yet had their TLB entries invalidated.
39 * Also, as ARMv7 speculative prefetch can drag new entries into the TLB,
40 * we need to apply this same delaying tactic to ensure correct operation.
42 #if defined(CONFIG_SMP) || defined(CONFIG_CPU_32v7)
43 #define tlb_fast_mode(tlb) 0
45 #define tlb_fast_mode(tlb) 1
48 #define MMU_GATHER_BUNDLE 8
51 * TLB handling. This allows us to remove pages from the page
52 * tables, and efficiently handle the TLB issues.
57 struct vm_area_struct *vma;
58 unsigned long range_start;
59 unsigned long range_end;
63 struct page *local[MMU_GATHER_BUNDLE];
66 DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
69 * This is unnecessarily complex. There's three ways the TLB shootdown
71 * 1. Unmapping a range of vmas. See zap_page_range(), unmap_region().
72 * tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
73 * tlb->vma will be non-NULL.
74 * 2. Unmapping all vmas. See exit_mmap().
75 * tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
76 * tlb->vma will be non-NULL. Additionally, page tables will be freed.
77 * 3. Unmapping argument pages. See shift_arg_pages().
78 * tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
79 * tlb->vma will be NULL.
81 static inline void tlb_flush(struct mmu_gather *tlb)
83 if (tlb->fullmm || !tlb->vma)
84 flush_tlb_mm(tlb->mm);
85 else if (tlb->range_end > 0) {
86 flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
87 tlb->range_start = TASK_SIZE;
92 static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
95 if (addr < tlb->range_start)
96 tlb->range_start = addr;
97 if (addr + PAGE_SIZE > tlb->range_end)
98 tlb->range_end = addr + PAGE_SIZE;
102 static inline void __tlb_alloc_page(struct mmu_gather *tlb)
104 unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
107 tlb->pages = (void *)addr;
108 tlb->max = PAGE_SIZE / sizeof(struct page *);
112 static inline void tlb_flush_mmu(struct mmu_gather *tlb)
115 if (!tlb_fast_mode(tlb)) {
116 free_pages_and_swap_cache(tlb->pages, tlb->nr);
118 if (tlb->pages == tlb->local)
119 __tlb_alloc_page(tlb);
124 tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int fullmm)
127 tlb->fullmm = fullmm;
129 tlb->max = ARRAY_SIZE(tlb->local);
130 tlb->pages = tlb->local;
132 __tlb_alloc_page(tlb);
136 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
140 /* keep the page table cache within bounds */
143 if (tlb->pages != tlb->local)
144 free_pages((unsigned long)tlb->pages, 0);
148 * Memorize the range for the TLB flush.
151 tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
153 tlb_add_flush(tlb, addr);
157 * In the case of tlb vma handling, we can optimise these away in the
158 * case where we're doing a full MM flush. When we're doing a munmap,
159 * the vmas are adjusted to only cover the region to be torn down.
162 tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
165 flush_cache_range(vma, vma->vm_start, vma->vm_end);
167 tlb->range_start = TASK_SIZE;
173 tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
179 static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
181 if (tlb_fast_mode(tlb)) {
182 free_page_and_swap_cache(page);
183 return 1; /* avoid calling tlb_flush_mmu */
186 tlb->pages[tlb->nr++] = page;
187 VM_BUG_ON(tlb->nr > tlb->max);
188 return tlb->max - tlb->nr;
191 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
193 if (!__tlb_remove_page(tlb, page))
197 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
200 pgtable_page_dtor(pte);
201 tlb_add_flush(tlb, addr);
202 tlb_remove_page(tlb, pte);
205 #define pte_free_tlb(tlb, ptep, addr) __pte_free_tlb(tlb, ptep, addr)
206 #define pmd_free_tlb(tlb, pmdp, addr) pmd_free((tlb)->mm, pmdp)
208 #define tlb_migrate_finish(mm) do { } while (0)
210 #endif /* CONFIG_MMU */