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1da177e4 LT |
1 | /* |
2 | * linux/arch/arm/mm/fault-armv.c | |
3 | * | |
4 | * Copyright (C) 1995 Linus Torvalds | |
5 | * Modifications for ARM processor (c) 1995-2002 Russell King | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | #include <linux/module.h> | |
12 | #include <linux/sched.h> | |
13 | #include <linux/kernel.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/bitops.h> | |
16 | #include <linux/vmalloc.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/pagemap.h> | |
19 | ||
20 | #include <asm/cacheflush.h> | |
21 | #include <asm/pgtable.h> | |
22 | #include <asm/tlbflush.h> | |
23 | ||
24 | static unsigned long shared_pte_mask = L_PTE_CACHEABLE; | |
25 | ||
26 | /* | |
27 | * We take the easy way out of this problem - we make the | |
28 | * PTE uncacheable. However, we leave the write buffer on. | |
29 | */ | |
30 | static int adjust_pte(struct vm_area_struct *vma, unsigned long address) | |
31 | { | |
32 | pgd_t *pgd; | |
33 | pmd_t *pmd; | |
34 | pte_t *pte, entry; | |
35 | int ret = 0; | |
36 | ||
37 | pgd = pgd_offset(vma->vm_mm, address); | |
38 | if (pgd_none(*pgd)) | |
39 | goto no_pgd; | |
40 | if (pgd_bad(*pgd)) | |
41 | goto bad_pgd; | |
42 | ||
43 | pmd = pmd_offset(pgd, address); | |
44 | if (pmd_none(*pmd)) | |
45 | goto no_pmd; | |
46 | if (pmd_bad(*pmd)) | |
47 | goto bad_pmd; | |
48 | ||
49 | pte = pte_offset_map(pmd, address); | |
50 | entry = *pte; | |
51 | ||
52 | /* | |
53 | * If this page isn't present, or is already setup to | |
54 | * fault (ie, is old), we can safely ignore any issues. | |
55 | */ | |
56 | if (pte_present(entry) && pte_val(entry) & shared_pte_mask) { | |
57 | flush_cache_page(vma, address, pte_pfn(entry)); | |
58 | pte_val(entry) &= ~shared_pte_mask; | |
59 | set_pte(pte, entry); | |
60 | flush_tlb_page(vma, address); | |
61 | ret = 1; | |
62 | } | |
63 | pte_unmap(pte); | |
64 | return ret; | |
65 | ||
66 | bad_pgd: | |
67 | pgd_ERROR(*pgd); | |
68 | pgd_clear(pgd); | |
69 | no_pgd: | |
70 | return 0; | |
71 | ||
72 | bad_pmd: | |
73 | pmd_ERROR(*pmd); | |
74 | pmd_clear(pmd); | |
75 | no_pmd: | |
76 | return 0; | |
77 | } | |
78 | ||
79 | static void | |
8830f04a | 80 | make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn) |
1da177e4 | 81 | { |
1da177e4 LT |
82 | struct mm_struct *mm = vma->vm_mm; |
83 | struct vm_area_struct *mpnt; | |
84 | struct prio_tree_iter iter; | |
85 | unsigned long offset; | |
86 | pgoff_t pgoff; | |
87 | int aliases = 0; | |
88 | ||
1da177e4 LT |
89 | pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT); |
90 | ||
91 | /* | |
92 | * If we have any shared mappings that are in the same mm | |
93 | * space, then we need to handle them specially to maintain | |
94 | * cache coherency. | |
95 | */ | |
96 | flush_dcache_mmap_lock(mapping); | |
97 | vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
98 | /* | |
99 | * If this VMA is not in our MM, we can ignore it. | |
100 | * Note that we intentionally mask out the VMA | |
101 | * that we are fixing up. | |
102 | */ | |
103 | if (mpnt->vm_mm != mm || mpnt == vma) | |
104 | continue; | |
105 | if (!(mpnt->vm_flags & VM_MAYSHARE)) | |
106 | continue; | |
107 | offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT; | |
108 | aliases += adjust_pte(mpnt, mpnt->vm_start + offset); | |
109 | } | |
110 | flush_dcache_mmap_unlock(mapping); | |
111 | if (aliases) | |
112 | adjust_pte(vma, addr); | |
113 | else | |
8830f04a | 114 | flush_cache_page(vma, addr, pfn); |
1da177e4 LT |
115 | } |
116 | ||
8830f04a RK |
117 | void __flush_dcache_page(struct address_space *mapping, struct page *page); |
118 | ||
1da177e4 LT |
119 | /* |
120 | * Take care of architecture specific things when placing a new PTE into | |
121 | * a page table, or changing an existing PTE. Basically, there are two | |
122 | * things that we need to take care of: | |
123 | * | |
124 | * 1. If PG_dcache_dirty is set for the page, we need to ensure | |
125 | * that any cache entries for the kernels virtual memory | |
126 | * range are written back to the page. | |
127 | * 2. If we have multiple shared mappings of the same space in | |
128 | * an object, we need to deal with the cache aliasing issues. | |
129 | * | |
130 | * Note that the page_table_lock will be held. | |
131 | */ | |
132 | void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte) | |
133 | { | |
134 | unsigned long pfn = pte_pfn(pte); | |
8830f04a | 135 | struct address_space *mapping; |
1da177e4 LT |
136 | struct page *page; |
137 | ||
138 | if (!pfn_valid(pfn)) | |
139 | return; | |
8830f04a | 140 | |
1da177e4 | 141 | page = pfn_to_page(pfn); |
8830f04a RK |
142 | mapping = page_mapping(page); |
143 | if (mapping) { | |
1da177e4 LT |
144 | int dirty = test_and_clear_bit(PG_dcache_dirty, &page->flags); |
145 | ||
8830f04a RK |
146 | if (dirty) |
147 | __flush_dcache_page(mapping, page); | |
1da177e4 LT |
148 | |
149 | if (cache_is_vivt()) | |
8830f04a | 150 | make_coherent(mapping, vma, addr, pfn); |
1da177e4 LT |
151 | } |
152 | } | |
153 | ||
154 | /* | |
155 | * Check whether the write buffer has physical address aliasing | |
156 | * issues. If it has, we need to avoid them for the case where | |
157 | * we have several shared mappings of the same object in user | |
158 | * space. | |
159 | */ | |
160 | static int __init check_writebuffer(unsigned long *p1, unsigned long *p2) | |
161 | { | |
162 | register unsigned long zero = 0, one = 1, val; | |
163 | ||
164 | local_irq_disable(); | |
165 | mb(); | |
166 | *p1 = one; | |
167 | mb(); | |
168 | *p2 = zero; | |
169 | mb(); | |
170 | val = *p1; | |
171 | mb(); | |
172 | local_irq_enable(); | |
173 | return val != zero; | |
174 | } | |
175 | ||
176 | void __init check_writebuffer_bugs(void) | |
177 | { | |
178 | struct page *page; | |
179 | const char *reason; | |
180 | unsigned long v = 1; | |
181 | ||
182 | printk(KERN_INFO "CPU: Testing write buffer coherency: "); | |
183 | ||
184 | page = alloc_page(GFP_KERNEL); | |
185 | if (page) { | |
186 | unsigned long *p1, *p2; | |
187 | pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG| | |
188 | L_PTE_DIRTY|L_PTE_WRITE| | |
189 | L_PTE_BUFFERABLE); | |
190 | ||
191 | p1 = vmap(&page, 1, VM_IOREMAP, prot); | |
192 | p2 = vmap(&page, 1, VM_IOREMAP, prot); | |
193 | ||
194 | if (p1 && p2) { | |
195 | v = check_writebuffer(p1, p2); | |
196 | reason = "enabling work-around"; | |
197 | } else { | |
198 | reason = "unable to map memory\n"; | |
199 | } | |
200 | ||
201 | vunmap(p1); | |
202 | vunmap(p2); | |
203 | put_page(page); | |
204 | } else { | |
205 | reason = "unable to grab page\n"; | |
206 | } | |
207 | ||
208 | if (v) { | |
209 | printk("failed, %s\n", reason); | |
210 | shared_pte_mask |= L_PTE_BUFFERABLE; | |
211 | } else { | |
212 | printk("ok\n"); | |
213 | } | |
214 | } |