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1da177e4 LT |
1 | /* |
2 | * Copyright 2002 Andi Kleen, SuSE Labs. | |
3 | * Thanks to Ben LaHaise for precious feedback. | |
4 | */ | |
5 | ||
6 | #include <linux/config.h> | |
7 | #include <linux/mm.h> | |
8 | #include <linux/sched.h> | |
9 | #include <linux/highmem.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/slab.h> | |
12 | #include <asm/uaccess.h> | |
13 | #include <asm/processor.h> | |
14 | #include <asm/tlbflush.h> | |
15 | #include <asm/io.h> | |
16 | ||
17 | static inline pte_t *lookup_address(unsigned long address) | |
18 | { | |
19 | pgd_t *pgd = pgd_offset_k(address); | |
20 | pud_t *pud; | |
21 | pmd_t *pmd; | |
22 | pte_t *pte; | |
23 | if (pgd_none(*pgd)) | |
24 | return NULL; | |
25 | pud = pud_offset(pgd, address); | |
26 | if (!pud_present(*pud)) | |
27 | return NULL; | |
28 | pmd = pmd_offset(pud, address); | |
29 | if (!pmd_present(*pmd)) | |
30 | return NULL; | |
31 | if (pmd_large(*pmd)) | |
32 | return (pte_t *)pmd; | |
33 | pte = pte_offset_kernel(pmd, address); | |
34 | if (pte && !pte_present(*pte)) | |
35 | pte = NULL; | |
36 | return pte; | |
37 | } | |
38 | ||
39 | static struct page *split_large_page(unsigned long address, pgprot_t prot, | |
40 | pgprot_t ref_prot) | |
41 | { | |
42 | int i; | |
43 | unsigned long addr; | |
44 | struct page *base = alloc_pages(GFP_KERNEL, 0); | |
45 | pte_t *pbase; | |
46 | if (!base) | |
47 | return NULL; | |
48 | address = __pa(address); | |
49 | addr = address & LARGE_PAGE_MASK; | |
50 | pbase = (pte_t *)page_address(base); | |
51 | for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) { | |
52 | pbase[i] = pfn_pte(addr >> PAGE_SHIFT, | |
53 | addr == address ? prot : ref_prot); | |
54 | } | |
55 | return base; | |
56 | } | |
57 | ||
58 | ||
59 | static void flush_kernel_map(void *address) | |
60 | { | |
61 | if (0 && address && cpu_has_clflush) { | |
62 | /* is this worth it? */ | |
63 | int i; | |
64 | for (i = 0; i < PAGE_SIZE; i += boot_cpu_data.x86_clflush_size) | |
65 | asm volatile("clflush (%0)" :: "r" (address + i)); | |
66 | } else | |
67 | asm volatile("wbinvd":::"memory"); | |
68 | if (address) | |
69 | __flush_tlb_one(address); | |
70 | else | |
71 | __flush_tlb_all(); | |
72 | } | |
73 | ||
74 | ||
75 | static inline void flush_map(unsigned long address) | |
76 | { | |
77 | on_each_cpu(flush_kernel_map, (void *)address, 1, 1); | |
78 | } | |
79 | ||
80 | struct deferred_page { | |
81 | struct deferred_page *next; | |
82 | struct page *fpage; | |
83 | unsigned long address; | |
84 | }; | |
85 | static struct deferred_page *df_list; /* protected by init_mm.mmap_sem */ | |
86 | ||
87 | static inline void save_page(unsigned long address, struct page *fpage) | |
88 | { | |
89 | struct deferred_page *df; | |
90 | df = kmalloc(sizeof(struct deferred_page), GFP_KERNEL); | |
91 | if (!df) { | |
92 | flush_map(address); | |
93 | __free_page(fpage); | |
94 | } else { | |
95 | df->next = df_list; | |
96 | df->fpage = fpage; | |
97 | df->address = address; | |
98 | df_list = df; | |
99 | } | |
100 | } | |
101 | ||
102 | /* | |
103 | * No more special protections in this 2/4MB area - revert to a | |
104 | * large page again. | |
105 | */ | |
106 | static void revert_page(unsigned long address, pgprot_t ref_prot) | |
107 | { | |
108 | pgd_t *pgd; | |
109 | pud_t *pud; | |
110 | pmd_t *pmd; | |
111 | pte_t large_pte; | |
112 | ||
113 | pgd = pgd_offset_k(address); | |
114 | BUG_ON(pgd_none(*pgd)); | |
115 | pud = pud_offset(pgd,address); | |
116 | BUG_ON(pud_none(*pud)); | |
117 | pmd = pmd_offset(pud, address); | |
118 | BUG_ON(pmd_val(*pmd) & _PAGE_PSE); | |
119 | pgprot_val(ref_prot) |= _PAGE_PSE; | |
120 | large_pte = mk_pte_phys(__pa(address) & LARGE_PAGE_MASK, ref_prot); | |
121 | set_pte((pte_t *)pmd, large_pte); | |
122 | } | |
123 | ||
124 | static int | |
125 | __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot, | |
126 | pgprot_t ref_prot) | |
127 | { | |
128 | pte_t *kpte; | |
129 | struct page *kpte_page; | |
130 | unsigned kpte_flags; | |
131 | kpte = lookup_address(address); | |
132 | if (!kpte) return 0; | |
133 | kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK); | |
134 | kpte_flags = pte_val(*kpte); | |
135 | if (pgprot_val(prot) != pgprot_val(ref_prot)) { | |
136 | if ((kpte_flags & _PAGE_PSE) == 0) { | |
137 | set_pte(kpte, pfn_pte(pfn, prot)); | |
138 | } else { | |
139 | /* | |
140 | * split_large_page will take the reference for this change_page_attr | |
141 | * on the split page. | |
142 | */ | |
143 | struct page *split = split_large_page(address, prot, ref_prot); | |
144 | if (!split) | |
145 | return -ENOMEM; | |
146 | set_pte(kpte,mk_pte(split, ref_prot)); | |
147 | kpte_page = split; | |
148 | } | |
149 | get_page(kpte_page); | |
150 | } else if ((kpte_flags & _PAGE_PSE) == 0) { | |
151 | set_pte(kpte, pfn_pte(pfn, ref_prot)); | |
152 | __put_page(kpte_page); | |
153 | } else | |
154 | BUG(); | |
155 | ||
156 | /* on x86-64 the direct mapping set at boot is not using 4k pages */ | |
157 | BUG_ON(PageReserved(kpte_page)); | |
158 | ||
159 | switch (page_count(kpte_page)) { | |
160 | case 1: | |
161 | save_page(address, kpte_page); | |
162 | revert_page(address, ref_prot); | |
163 | break; | |
164 | case 0: | |
165 | BUG(); /* memleak and failed 2M page regeneration */ | |
166 | } | |
167 | return 0; | |
168 | } | |
169 | ||
170 | /* | |
171 | * Change the page attributes of an page in the linear mapping. | |
172 | * | |
173 | * This should be used when a page is mapped with a different caching policy | |
174 | * than write-back somewhere - some CPUs do not like it when mappings with | |
175 | * different caching policies exist. This changes the page attributes of the | |
176 | * in kernel linear mapping too. | |
177 | * | |
178 | * The caller needs to ensure that there are no conflicting mappings elsewhere. | |
179 | * This function only deals with the kernel linear map. | |
180 | * | |
181 | * Caller must call global_flush_tlb() after this. | |
182 | */ | |
183 | int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot) | |
184 | { | |
185 | int err = 0; | |
186 | int i; | |
187 | ||
188 | down_write(&init_mm.mmap_sem); | |
189 | for (i = 0; i < numpages; i++, address += PAGE_SIZE) { | |
190 | unsigned long pfn = __pa(address) >> PAGE_SHIFT; | |
191 | ||
192 | err = __change_page_attr(address, pfn, prot, PAGE_KERNEL); | |
193 | if (err) | |
194 | break; | |
195 | /* Handle kernel mapping too which aliases part of the | |
196 | * lowmem */ | |
197 | if (__pa(address) < KERNEL_TEXT_SIZE) { | |
198 | unsigned long addr2; | |
199 | pgprot_t prot2 = prot; | |
200 | addr2 = __START_KERNEL_map + __pa(address); | |
201 | pgprot_val(prot2) &= ~_PAGE_NX; | |
202 | err = __change_page_attr(addr2, pfn, prot2, PAGE_KERNEL_EXEC); | |
203 | } | |
204 | } | |
205 | up_write(&init_mm.mmap_sem); | |
206 | return err; | |
207 | } | |
208 | ||
209 | /* Don't call this for MMIO areas that may not have a mem_map entry */ | |
210 | int change_page_attr(struct page *page, int numpages, pgprot_t prot) | |
211 | { | |
212 | unsigned long addr = (unsigned long)page_address(page); | |
213 | return change_page_attr_addr(addr, numpages, prot); | |
214 | } | |
215 | ||
216 | void global_flush_tlb(void) | |
217 | { | |
218 | struct deferred_page *df, *next_df; | |
219 | ||
220 | down_read(&init_mm.mmap_sem); | |
221 | df = xchg(&df_list, NULL); | |
222 | up_read(&init_mm.mmap_sem); | |
1da177e4 LT |
223 | flush_map((df && !df->next) ? df->address : 0); |
224 | for (; df; df = next_df) { | |
225 | next_df = df->next; | |
226 | if (df->fpage) | |
227 | __free_page(df->fpage); | |
228 | kfree(df); | |
229 | } | |
230 | } | |
231 | ||
232 | EXPORT_SYMBOL(change_page_attr); | |
233 | EXPORT_SYMBOL(global_flush_tlb); |