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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 | ||
09d9bae0 | 20 | #include <asm/bugs.h> |
1da177e4 | 21 | #include <asm/cacheflush.h> |
46097c7d | 22 | #include <asm/cachetype.h> |
1da177e4 LT |
23 | #include <asm/pgtable.h> |
24 | #include <asm/tlbflush.h> | |
25 | ||
7b0a1003 RK |
26 | #include "mm.h" |
27 | ||
bb30f36f | 28 | static unsigned long shared_pte_mask = L_PTE_MT_BUFFERABLE; |
1da177e4 LT |
29 | |
30 | /* | |
31 | * We take the easy way out of this problem - we make the | |
32 | * PTE uncacheable. However, we leave the write buffer on. | |
69b04754 HD |
33 | * |
34 | * Note that the pte lock held when calling update_mmu_cache must also | |
35 | * guard the pte (somewhere else in the same mm) that we modify here. | |
36 | * Therefore those configurations which might call adjust_pte (those | |
37 | * without CONFIG_CPU_CACHE_VIPT) cannot support split page_table_lock. | |
1da177e4 LT |
38 | */ |
39 | static int adjust_pte(struct vm_area_struct *vma, unsigned long address) | |
40 | { | |
41 | pgd_t *pgd; | |
42 | pmd_t *pmd; | |
43 | pte_t *pte, entry; | |
53cdb27a | 44 | int ret; |
1da177e4 LT |
45 | |
46 | pgd = pgd_offset(vma->vm_mm, address); | |
47 | if (pgd_none(*pgd)) | |
48 | goto no_pgd; | |
49 | if (pgd_bad(*pgd)) | |
50 | goto bad_pgd; | |
51 | ||
52 | pmd = pmd_offset(pgd, address); | |
53 | if (pmd_none(*pmd)) | |
54 | goto no_pmd; | |
55 | if (pmd_bad(*pmd)) | |
56 | goto bad_pmd; | |
57 | ||
58 | pte = pte_offset_map(pmd, address); | |
59 | entry = *pte; | |
60 | ||
53cdb27a RK |
61 | /* |
62 | * If this page is present, it's actually being shared. | |
63 | */ | |
64 | ret = pte_present(entry); | |
65 | ||
1da177e4 LT |
66 | /* |
67 | * If this page isn't present, or is already setup to | |
68 | * fault (ie, is old), we can safely ignore any issues. | |
69 | */ | |
bb30f36f | 70 | if (ret && (pte_val(entry) & L_PTE_MT_MASK) != shared_pte_mask) { |
08e445bd NP |
71 | unsigned long pfn = pte_pfn(entry); |
72 | flush_cache_page(vma, address, pfn); | |
73 | outer_flush_range((pfn << PAGE_SHIFT), | |
74 | (pfn << PAGE_SHIFT) + PAGE_SIZE); | |
bb30f36f RK |
75 | pte_val(entry) &= ~L_PTE_MT_MASK; |
76 | pte_val(entry) |= shared_pte_mask; | |
ad1ae2fe | 77 | set_pte_at(vma->vm_mm, address, pte, entry); |
1da177e4 | 78 | flush_tlb_page(vma, address); |
1da177e4 LT |
79 | } |
80 | pte_unmap(pte); | |
81 | return ret; | |
82 | ||
83 | bad_pgd: | |
84 | pgd_ERROR(*pgd); | |
85 | pgd_clear(pgd); | |
86 | no_pgd: | |
87 | return 0; | |
88 | ||
89 | bad_pmd: | |
90 | pmd_ERROR(*pmd); | |
91 | pmd_clear(pmd); | |
92 | no_pmd: | |
93 | return 0; | |
94 | } | |
95 | ||
96 | static void | |
8830f04a | 97 | make_coherent(struct address_space *mapping, struct vm_area_struct *vma, unsigned long addr, unsigned long pfn) |
1da177e4 | 98 | { |
1da177e4 LT |
99 | struct mm_struct *mm = vma->vm_mm; |
100 | struct vm_area_struct *mpnt; | |
101 | struct prio_tree_iter iter; | |
102 | unsigned long offset; | |
103 | pgoff_t pgoff; | |
104 | int aliases = 0; | |
105 | ||
1da177e4 LT |
106 | pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT); |
107 | ||
108 | /* | |
109 | * If we have any shared mappings that are in the same mm | |
110 | * space, then we need to handle them specially to maintain | |
111 | * cache coherency. | |
112 | */ | |
113 | flush_dcache_mmap_lock(mapping); | |
114 | vma_prio_tree_foreach(mpnt, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
115 | /* | |
116 | * If this VMA is not in our MM, we can ignore it. | |
117 | * Note that we intentionally mask out the VMA | |
118 | * that we are fixing up. | |
119 | */ | |
120 | if (mpnt->vm_mm != mm || mpnt == vma) | |
121 | continue; | |
122 | if (!(mpnt->vm_flags & VM_MAYSHARE)) | |
123 | continue; | |
124 | offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT; | |
125 | aliases += adjust_pte(mpnt, mpnt->vm_start + offset); | |
126 | } | |
127 | flush_dcache_mmap_unlock(mapping); | |
128 | if (aliases) | |
129 | adjust_pte(vma, addr); | |
130 | else | |
8830f04a | 131 | flush_cache_page(vma, addr, pfn); |
1da177e4 LT |
132 | } |
133 | ||
134 | /* | |
135 | * Take care of architecture specific things when placing a new PTE into | |
136 | * a page table, or changing an existing PTE. Basically, there are two | |
137 | * things that we need to take care of: | |
138 | * | |
139 | * 1. If PG_dcache_dirty is set for the page, we need to ensure | |
140 | * that any cache entries for the kernels virtual memory | |
141 | * range are written back to the page. | |
142 | * 2. If we have multiple shared mappings of the same space in | |
143 | * an object, we need to deal with the cache aliasing issues. | |
144 | * | |
69b04754 | 145 | * Note that the pte lock will be held. |
1da177e4 LT |
146 | */ |
147 | void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr, pte_t pte) | |
148 | { | |
149 | unsigned long pfn = pte_pfn(pte); | |
8830f04a | 150 | struct address_space *mapping; |
1da177e4 LT |
151 | struct page *page; |
152 | ||
153 | if (!pfn_valid(pfn)) | |
154 | return; | |
8830f04a | 155 | |
421fe93c RK |
156 | /* |
157 | * The zero page is never written to, so never has any dirty | |
158 | * cache lines, and therefore never needs to be flushed. | |
159 | */ | |
1da177e4 | 160 | page = pfn_to_page(pfn); |
421fe93c RK |
161 | if (page == ZERO_PAGE(0)) |
162 | return; | |
163 | ||
8830f04a | 164 | mapping = page_mapping(page); |
826cbdaf | 165 | #ifndef CONFIG_SMP |
787b2faa NG |
166 | if (test_and_clear_bit(PG_dcache_dirty, &page->flags)) |
167 | __flush_dcache_page(mapping, page); | |
826cbdaf | 168 | #endif |
787b2faa | 169 | if (mapping) { |
1da177e4 | 170 | if (cache_is_vivt()) |
8830f04a | 171 | make_coherent(mapping, vma, addr, pfn); |
826cbdaf CM |
172 | else if (vma->vm_flags & VM_EXEC) |
173 | __flush_icache_all(); | |
1da177e4 LT |
174 | } |
175 | } | |
176 | ||
177 | /* | |
178 | * Check whether the write buffer has physical address aliasing | |
179 | * issues. If it has, we need to avoid them for the case where | |
180 | * we have several shared mappings of the same object in user | |
181 | * space. | |
182 | */ | |
183 | static int __init check_writebuffer(unsigned long *p1, unsigned long *p2) | |
184 | { | |
185 | register unsigned long zero = 0, one = 1, val; | |
186 | ||
187 | local_irq_disable(); | |
188 | mb(); | |
189 | *p1 = one; | |
190 | mb(); | |
191 | *p2 = zero; | |
192 | mb(); | |
193 | val = *p1; | |
194 | mb(); | |
195 | local_irq_enable(); | |
196 | return val != zero; | |
197 | } | |
198 | ||
199 | void __init check_writebuffer_bugs(void) | |
200 | { | |
201 | struct page *page; | |
202 | const char *reason; | |
203 | unsigned long v = 1; | |
204 | ||
205 | printk(KERN_INFO "CPU: Testing write buffer coherency: "); | |
206 | ||
207 | page = alloc_page(GFP_KERNEL); | |
208 | if (page) { | |
209 | unsigned long *p1, *p2; | |
210 | pgprot_t prot = __pgprot(L_PTE_PRESENT|L_PTE_YOUNG| | |
211 | L_PTE_DIRTY|L_PTE_WRITE| | |
bb30f36f | 212 | L_PTE_MT_BUFFERABLE); |
1da177e4 LT |
213 | |
214 | p1 = vmap(&page, 1, VM_IOREMAP, prot); | |
215 | p2 = vmap(&page, 1, VM_IOREMAP, prot); | |
216 | ||
217 | if (p1 && p2) { | |
218 | v = check_writebuffer(p1, p2); | |
219 | reason = "enabling work-around"; | |
220 | } else { | |
221 | reason = "unable to map memory\n"; | |
222 | } | |
223 | ||
224 | vunmap(p1); | |
225 | vunmap(p2); | |
226 | put_page(page); | |
227 | } else { | |
228 | reason = "unable to grab page\n"; | |
229 | } | |
230 | ||
231 | if (v) { | |
232 | printk("failed, %s\n", reason); | |
bb30f36f | 233 | shared_pte_mask = L_PTE_MT_UNCACHED; |
1da177e4 LT |
234 | } else { |
235 | printk("ok\n"); | |
236 | } | |
237 | } |