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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. | |
69b04754 HD |
29 | * |
30 | * Note that the pte lock held when calling update_mmu_cache must also | |
31 | * guard the pte (somewhere else in the same mm) that we modify here. | |
32 | * Therefore those configurations which might call adjust_pte (those | |
33 | * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock. | |
1da177e4 LT |
34 | */ |
35 | static int adjust_pte(struct vm_area_struct *vma, unsigned long address) | |
36 | { | |
37 | pgd_t *pgd; | |
38 | pmd_t *pmd; | |
39 | pte_t *pte, entry; | |
53cdb27a | 40 | int ret; |
1da177e4 LT |
41 | |
42 | pgd = pgd_offset(vma->vm_mm, address); | |
43 | if (pgd_none(*pgd)) | |
44 | goto no_pgd; | |
45 | if (pgd_bad(*pgd)) | |
46 | goto bad_pgd; | |
47 | ||
48 | pmd = pmd_offset(pgd, address); | |
49 | if (pmd_none(*pmd)) | |
50 | goto no_pmd; | |
51 | if (pmd_bad(*pmd)) | |
52 | goto bad_pmd; | |
53 | ||
54 | pte = pte_offset_map(pmd, address); | |
55 | entry = *pte; | |
56 | ||
53cdb27a RK |
57 | /* |
58 | * If this page is present, it's actually being shared. | |
59 | */ | |
60 | ret = pte_present(entry); | |
61 | ||
1da177e4 LT |
62 | /* |
63 | * If this page isn't present, or is already setup to | |
64 | * fault (ie, is old), we can safely ignore any issues. | |
65 | */ | |
53cdb27a | 66 | if (ret && pte_val(entry) & shared_pte_mask) { |
1da177e4 LT |
67 | flush_cache_page(vma, address, pte_pfn(entry)); |
68 | pte_val(entry) &= ~shared_pte_mask; | |
ad1ae2fe | 69 | set_pte_at(vma->vm_mm, address, pte, entry); |
1da177e4 | 70 | flush_tlb_page(vma, address); |
1da177e4 LT |
71 | } |
72 | pte_unmap(pte); | |
73 | return ret; | |
74 | ||
75 | bad_pgd: | |
76 | pgd_ERROR(*pgd); | |
77 | pgd_clear(pgd); | |
78 | no_pgd: | |
79 | return 0; | |
80 | ||
81 | bad_pmd: | |
82 | pmd_ERROR(*pmd); | |
83 | pmd_clear(pmd); | |
84 | no_pmd: | |
85 | return 0; | |
86 | } | |
87 | ||
88 | static void | |
8830f04a | 89 | make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn) |
1da177e4 | 90 | { |
1da177e4 LT |
91 | struct mm_struct *mm = vma->vm_mm; |
92 | struct vm_area_struct *mpnt; | |
93 | struct prio_tree_iter iter; | |
94 | unsigned long offset; | |
95 | pgoff_t pgoff; | |
96 | int aliases = 0; | |
97 | ||
1da177e4 LT |
98 | pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT); |
99 | ||
100 | /* | |
101 | * If we have any shared mappings that are in the same mm | |
102 | * space, then we need to handle them specially to maintain | |
103 | * cache coherency. | |
104 | */ | |
105 | flush_dcache_mmap_lock(mapping); | |
106 | vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
107 | /* | |
108 | * If this VMA is not in our MM, we can ignore it. | |
109 | * Note that we intentionally mask out the VMA | |
110 | * that we are fixing up. | |
111 | */ | |
112 | if (mpnt->vm_mm != mm || mpnt == vma) | |
113 | continue; | |
114 | if (!(mpnt->vm_flags & VM_MAYSHARE)) | |
115 | continue; | |
116 | offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT; | |
117 | aliases += adjust_pte(mpnt, mpnt->vm_start + offset); | |
118 | } | |
119 | flush_dcache_mmap_unlock(mapping); | |
120 | if (aliases) | |
121 | adjust_pte(vma, addr); | |
122 | else | |
8830f04a | 123 | flush_cache_page(vma, addr, pfn); |
1da177e4 LT |
124 | } |
125 | ||
126 | /* | |
127 | * Take care of architecture specific things when placing a new PTE into | |
128 | * a page table, or changing an existing PTE. Basically, there are two | |
129 | * things that we need to take care of: | |
130 | * | |
131 | * 1. If PG_dcache_dirty is set for the page, we need to ensure | |
132 | * that any cache entries for the kernels virtual memory | |
133 | * range are written back to the page. | |
134 | * 2. If we have multiple shared mappings of the same space in | |
135 | * an object, we need to deal with the cache aliasing issues. | |
136 | * | |
69b04754 | 137 | * Note that the pte lock will be held. |
1da177e4 LT |
138 | */ |
139 | void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte) | |
140 | { | |
141 | unsigned long pfn = pte_pfn(pte); | |
8830f04a | 142 | struct address_space *mapping; |
1da177e4 LT |
143 | struct page *page; |
144 | ||
145 | if (!pfn_valid(pfn)) | |
146 | return; | |
8830f04a | 147 | |
1da177e4 | 148 | page = pfn_to_page(pfn); |
8830f04a RK |
149 | mapping = page_mapping(page); |
150 | if (mapping) { | |
826cbdaf | 151 | #ifndef CONFIG_SMP |
1da177e4 LT |
152 | int dirty = test_and_clear_bit(PG_dcache_dirty, &page->flags); |
153 | ||
8830f04a RK |
154 | if (dirty) |
155 | __flush_dcache_page(mapping, page); | |
826cbdaf | 156 | #endif |
1da177e4 LT |
157 | |
158 | if (cache_is_vivt()) | |
8830f04a | 159 | make_coherent(mapping, vma, addr, pfn); |
826cbdaf CM |
160 | else if (vma->vm_flags & VM_EXEC) |
161 | __flush_icache_all(); | |
1da177e4 LT |
162 | } |
163 | } | |
164 | ||
165 | /* | |
166 | * Check whether the write buffer has physical address aliasing | |
167 | * issues. If it has, we need to avoid them for the case where | |
168 | * we have several shared mappings of the same object in user | |
169 | * space. | |
170 | */ | |
171 | static int __init check_writebuffer(unsigned long *p1, unsigned long *p2) | |
172 | { | |
173 | register unsigned long zero = 0, one = 1, val; | |
174 | ||
175 | local_irq_disable(); | |
176 | mb(); | |
177 | *p1 = one; | |
178 | mb(); | |
179 | *p2 = zero; | |
180 | mb(); | |
181 | val = *p1; | |
182 | mb(); | |
183 | local_irq_enable(); | |
184 | return val != zero; | |
185 | } | |
186 | ||
187 | void __init check_writebuffer_bugs(void) | |
188 | { | |
189 | struct page *page; | |
190 | const char *reason; | |
191 | unsigned long v = 1; | |
192 | ||
193 | printk(KERN_INFO "CPU: Testing write buffer coherency: "); | |
194 | ||
195 | page = alloc_page(GFP_KERNEL); | |
196 | if (page) { | |
197 | unsigned long *p1, *p2; | |
198 | pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG| | |
199 | L_PTE_DIRTY|L_PTE_WRITE| | |
200 | L_PTE_BUFFERABLE); | |
201 | ||
202 | p1 = vmap(&page, 1, VM_IOREMAP, prot); | |
203 | p2 = vmap(&page, 1, VM_IOREMAP, prot); | |
204 | ||
205 | if (p1 && p2) { | |
206 | v = check_writebuffer(p1, p2); | |
207 | reason = "enabling work-around"; | |
208 | } else { | |
209 | reason = "unable to map memory\n"; | |
210 | } | |
211 | ||
212 | vunmap(p1); | |
213 | vunmap(p2); | |
214 | put_page(page); | |
215 | } else { | |
216 | reason = "unable to grab page\n"; | |
217 | } | |
218 | ||
219 | if (v) { | |
220 | printk("failed, %s\n", reason); | |
221 | shared_pte_mask |= L_PTE_BUFFERABLE; | |
222 | } else { | |
223 | printk("ok\n"); | |
224 | } | |
225 | } |