1/*
2 *  arch/arm/include/asm/tlb.h
3 *
4 *  Copyright (C) 2002 Russell King
5 *
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.
9 *
10 *  Experimentation shows that on a StrongARM, it appears to be faster
11 *  to use the "invalidate whole tlb" rather than "invalidate single
12 *  tlb" for this.
13 *
14 *  This appears true for both the process fork+exit case, as well as
15 *  the munmap-large-area case.
16 */
17#ifndef __ASMARM_TLB_H
18#define __ASMARM_TLB_H
19
20#include <asm/cacheflush.h>
21
22#ifndef CONFIG_MMU
23
24#include <linux/pagemap.h>
25
26#define tlb_flush(tlb)	((void) tlb)
27
28#include <asm-generic/tlb.h>
29
30#else /* !CONFIG_MMU */
31
32#include <linux/swap.h>
33#include <asm/pgalloc.h>
34#include <asm/tlbflush.h>
35
36#define MMU_GATHER_BUNDLE	8
37
38#ifdef CONFIG_HAVE_RCU_TABLE_FREE
39static inline void __tlb_remove_table(void *_table)
40{
41	free_page_and_swap_cache((struct page *)_table);
42}
43
44struct mmu_table_batch {
45	struct rcu_head		rcu;
46	unsigned int		nr;
47	void			*tables[0];
48};
49
50#define MAX_TABLE_BATCH		\
51	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
52
53extern void tlb_table_flush(struct mmu_gather *tlb);
54extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
55
56#define tlb_remove_entry(tlb, entry)	tlb_remove_table(tlb, entry)
57#else
58#define tlb_remove_entry(tlb, entry)	tlb_remove_page(tlb, entry)
59#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
60
61/*
62 * TLB handling.  This allows us to remove pages from the page
63 * tables, and efficiently handle the TLB issues.
64 */
65struct mmu_gather {
66	struct mm_struct	*mm;
67#ifdef CONFIG_HAVE_RCU_TABLE_FREE
68	struct mmu_table_batch	*batch;
69	unsigned int		need_flush;
70#endif
71	unsigned int		fullmm;
72	struct vm_area_struct	*vma;
73	unsigned long		start, end;
74	unsigned long		range_start;
75	unsigned long		range_end;
76	unsigned int		nr;
77	unsigned int		max;
78	struct page		**pages;
79	struct page		*local[MMU_GATHER_BUNDLE];
80};
81
82DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
83
84/*
85 * This is unnecessarily complex.  There's three ways the TLB shootdown
86 * code is used:
87 *  1. Unmapping a range of vmas.  See zap_page_range(), unmap_region().
88 *     tlb->fullmm = 0, and tlb_start_vma/tlb_end_vma will be called.
89 *     tlb->vma will be non-NULL.
90 *  2. Unmapping all vmas.  See exit_mmap().
91 *     tlb->fullmm = 1, and tlb_start_vma/tlb_end_vma will be called.
92 *     tlb->vma will be non-NULL.  Additionally, page tables will be freed.
93 *  3. Unmapping argument pages.  See shift_arg_pages().
94 *     tlb->fullmm = 0, but tlb_start_vma/tlb_end_vma will not be called.
95 *     tlb->vma will be NULL.
96 */
97static inline void tlb_flush(struct mmu_gather *tlb)
98{
99	if (tlb->fullmm || !tlb->vma)
100		flush_tlb_mm(tlb->mm);
101	else if (tlb->range_end > 0) {
102		flush_tlb_range(tlb->vma, tlb->range_start, tlb->range_end);
103		tlb->range_start = TASK_SIZE;
104		tlb->range_end = 0;
105	}
106}
107
108static inline void tlb_add_flush(struct mmu_gather *tlb, unsigned long addr)
109{
110	if (!tlb->fullmm) {
111		if (addr < tlb->range_start)
112			tlb->range_start = addr;
113		if (addr + PAGE_SIZE > tlb->range_end)
114			tlb->range_end = addr + PAGE_SIZE;
115	}
116}
117
118static inline void __tlb_alloc_page(struct mmu_gather *tlb)
119{
120	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
121
122	if (addr) {
123		tlb->pages = (void *)addr;
124		tlb->max = PAGE_SIZE / sizeof(struct page *);
125	}
126}
127
128static inline void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
129{
130	tlb_flush(tlb);
131#ifdef CONFIG_HAVE_RCU_TABLE_FREE
132	tlb_table_flush(tlb);
133#endif
134}
135
136static inline void tlb_flush_mmu_free(struct mmu_gather *tlb)
137{
138	free_pages_and_swap_cache(tlb->pages, tlb->nr);
139	tlb->nr = 0;
140	if (tlb->pages == tlb->local)
141		__tlb_alloc_page(tlb);
142}
143
144static inline void tlb_flush_mmu(struct mmu_gather *tlb)
145{
146	tlb_flush_mmu_tlbonly(tlb);
147	tlb_flush_mmu_free(tlb);
148}
149
150static inline void
151tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
152{
153	tlb->mm = mm;
154	tlb->fullmm = !(start | (end+1));
155	tlb->start = start;
156	tlb->end = end;
157	tlb->vma = NULL;
158	tlb->max = ARRAY_SIZE(tlb->local);
159	tlb->pages = tlb->local;
160	tlb->nr = 0;
161	__tlb_alloc_page(tlb);
162
163#ifdef CONFIG_HAVE_RCU_TABLE_FREE
164	tlb->batch = NULL;
165#endif
166}
167
168static inline void
169tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
170{
171	tlb_flush_mmu(tlb);
172
173	/* keep the page table cache within bounds */
174	check_pgt_cache();
175
176	if (tlb->pages != tlb->local)
177		free_pages((unsigned long)tlb->pages, 0);
178}
179
180/*
181 * Memorize the range for the TLB flush.
182 */
183static inline void
184tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
185{
186	tlb_add_flush(tlb, addr);
187}
188
189/*
190 * In the case of tlb vma handling, we can optimise these away in the
191 * case where we're doing a full MM flush.  When we're doing a munmap,
192 * the vmas are adjusted to only cover the region to be torn down.
193 */
194static inline void
195tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
196{
197	if (!tlb->fullmm) {
198		flush_cache_range(vma, vma->vm_start, vma->vm_end);
199		tlb->vma = vma;
200		tlb->range_start = TASK_SIZE;
201		tlb->range_end = 0;
202	}
203}
204
205static inline void
206tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
207{
208	if (!tlb->fullmm)
209		tlb_flush(tlb);
210}
211
212static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
213{
214	tlb->pages[tlb->nr++] = page;
215	VM_BUG_ON(tlb->nr > tlb->max);
216	return tlb->max - tlb->nr;
217}
218
219static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
220{
221	if (!__tlb_remove_page(tlb, page))
222		tlb_flush_mmu(tlb);
223}
224
225static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
226	unsigned long addr)
227{
228	pgtable_page_dtor(pte);
229
230#ifdef CONFIG_ARM_LPAE
231	tlb_add_flush(tlb, addr);
232#else
233	/*
234	 * With the classic ARM MMU, a pte page has two corresponding pmd
235	 * entries, each covering 1MB.
236	 */
237	addr &= PMD_MASK;
238	tlb_add_flush(tlb, addr + SZ_1M - PAGE_SIZE);
239	tlb_add_flush(tlb, addr + SZ_1M);
240#endif
241
242	tlb_remove_entry(tlb, pte);
243}
244
245static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
246				  unsigned long addr)
247{
248#ifdef CONFIG_ARM_LPAE
249	tlb_add_flush(tlb, addr);
250	tlb_remove_entry(tlb, virt_to_page(pmdp));
251#endif
252}
253
254static inline void
255tlb_remove_pmd_tlb_entry(struct mmu_gather *tlb, pmd_t *pmdp, unsigned long addr)
256{
257	tlb_add_flush(tlb, addr);
258}
259
260#define pte_free_tlb(tlb, ptep, addr)	__pte_free_tlb(tlb, ptep, addr)
261#define pmd_free_tlb(tlb, pmdp, addr)	__pmd_free_tlb(tlb, pmdp, addr)
262#define pud_free_tlb(tlb, pudp, addr)	pud_free((tlb)->mm, pudp)
263
264#define tlb_migrate_finish(mm)		do { } while (0)
265
266#endif /* CONFIG_MMU */
267#endif
268