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1da177e4 LT |
1 | /* |
2 | * linux/mm/fremap.c | |
3 | * | |
4 | * Explicit pagetable population and nonlinear (random) mappings support. | |
5 | * | |
6 | * started by Ingo Molnar, Copyright (C) 2002, 2003 | |
7 | */ | |
8 | ||
9 | #include <linux/mm.h> | |
10 | #include <linux/swap.h> | |
11 | #include <linux/file.h> | |
12 | #include <linux/mman.h> | |
13 | #include <linux/pagemap.h> | |
14 | #include <linux/swapops.h> | |
15 | #include <linux/rmap.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/syscalls.h> | |
18 | ||
19 | #include <asm/mmu_context.h> | |
20 | #include <asm/cacheflush.h> | |
21 | #include <asm/tlbflush.h> | |
22 | ||
861f2fb8 | 23 | static int zap_pte(struct mm_struct *mm, struct vm_area_struct *vma, |
1da177e4 LT |
24 | unsigned long addr, pte_t *ptep) |
25 | { | |
26 | pte_t pte = *ptep; | |
861f2fb8 | 27 | struct page *page = NULL; |
1da177e4 | 28 | |
1da177e4 | 29 | if (pte_present(pte)) { |
6aab341e | 30 | flush_cache_page(vma, addr, pte_pfn(pte)); |
1da177e4 | 31 | pte = ptep_clear_flush(vma, addr, ptep); |
6aab341e LT |
32 | page = vm_normal_page(vma, addr, pte); |
33 | if (page) { | |
34 | if (pte_dirty(pte)) | |
35 | set_page_dirty(page); | |
36 | page_remove_rmap(page); | |
37 | page_cache_release(page); | |
1da177e4 LT |
38 | } |
39 | } else { | |
40 | if (!pte_file(pte)) | |
41 | free_swap_and_cache(pte_to_swp_entry(pte)); | |
42 | pte_clear(mm, addr, ptep); | |
43 | } | |
861f2fb8 | 44 | return !!page; |
1da177e4 LT |
45 | } |
46 | ||
47 | /* | |
48 | * Install a file page to a given virtual memory address, release any | |
49 | * previously existing mapping. | |
50 | */ | |
51 | int install_page(struct mm_struct *mm, struct vm_area_struct *vma, | |
52 | unsigned long addr, struct page *page, pgprot_t prot) | |
53 | { | |
54 | struct inode *inode; | |
55 | pgoff_t size; | |
56 | int err = -ENOMEM; | |
57 | pte_t *pte; | |
58 | pmd_t *pmd; | |
59 | pud_t *pud; | |
60 | pgd_t *pgd; | |
61 | pte_t pte_val; | |
c74df32c | 62 | spinlock_t *ptl; |
1da177e4 LT |
63 | |
64 | pgd = pgd_offset(mm, addr); | |
1da177e4 LT |
65 | pud = pud_alloc(mm, pgd, addr); |
66 | if (!pud) | |
c74df32c | 67 | goto out; |
1da177e4 LT |
68 | pmd = pmd_alloc(mm, pud, addr); |
69 | if (!pmd) | |
c74df32c HD |
70 | goto out; |
71 | pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); | |
1da177e4 | 72 | if (!pte) |
c74df32c | 73 | goto out; |
1da177e4 LT |
74 | |
75 | /* | |
76 | * This page may have been truncated. Tell the | |
77 | * caller about it. | |
78 | */ | |
79 | err = -EINVAL; | |
80 | inode = vma->vm_file->f_mapping->host; | |
81 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; | |
82 | if (!page->mapping || page->index >= size) | |
c74df32c | 83 | goto unlock; |
f5154a98 HD |
84 | err = -ENOMEM; |
85 | if (page_mapcount(page) > INT_MAX/2) | |
c74df32c | 86 | goto unlock; |
1da177e4 | 87 | |
861f2fb8 HD |
88 | if (pte_none(*pte) || !zap_pte(mm, vma, addr, pte)) |
89 | inc_mm_counter(mm, file_rss); | |
1da177e4 | 90 | |
1da177e4 LT |
91 | flush_icache_page(vma, page); |
92 | set_pte_at(mm, addr, pte, mk_pte(page, prot)); | |
93 | page_add_file_rmap(page); | |
94 | pte_val = *pte; | |
1da177e4 | 95 | update_mmu_cache(vma, addr, pte_val); |
1da177e4 | 96 | err = 0; |
c74df32c HD |
97 | unlock: |
98 | pte_unmap_unlock(pte, ptl); | |
99 | out: | |
1da177e4 LT |
100 | return err; |
101 | } | |
102 | EXPORT_SYMBOL(install_page); | |
103 | ||
1da177e4 LT |
104 | /* |
105 | * Install a file pte to a given virtual memory address, release any | |
106 | * previously existing mapping. | |
107 | */ | |
108 | int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, | |
109 | unsigned long addr, unsigned long pgoff, pgprot_t prot) | |
110 | { | |
111 | int err = -ENOMEM; | |
112 | pte_t *pte; | |
113 | pmd_t *pmd; | |
114 | pud_t *pud; | |
115 | pgd_t *pgd; | |
116 | pte_t pte_val; | |
c74df32c | 117 | spinlock_t *ptl; |
1da177e4 LT |
118 | |
119 | pgd = pgd_offset(mm, addr); | |
1da177e4 LT |
120 | pud = pud_alloc(mm, pgd, addr); |
121 | if (!pud) | |
c74df32c | 122 | goto out; |
1da177e4 LT |
123 | pmd = pmd_alloc(mm, pud, addr); |
124 | if (!pmd) | |
c74df32c HD |
125 | goto out; |
126 | pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); | |
1da177e4 | 127 | if (!pte) |
c74df32c | 128 | goto out; |
1da177e4 | 129 | |
365e9c87 HD |
130 | if (!pte_none(*pte) && zap_pte(mm, vma, addr, pte)) { |
131 | update_hiwater_rss(mm); | |
861f2fb8 | 132 | dec_mm_counter(mm, file_rss); |
365e9c87 | 133 | } |
1da177e4 LT |
134 | |
135 | set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff)); | |
136 | pte_val = *pte; | |
1da177e4 | 137 | update_mmu_cache(vma, addr, pte_val); |
c74df32c HD |
138 | pte_unmap_unlock(pte, ptl); |
139 | err = 0; | |
140 | out: | |
1da177e4 LT |
141 | return err; |
142 | } | |
143 | ||
1da177e4 LT |
144 | /*** |
145 | * sys_remap_file_pages - remap arbitrary pages of a shared backing store | |
146 | * file within an existing vma. | |
147 | * @start: start of the remapped virtual memory range | |
148 | * @size: size of the remapped virtual memory range | |
149 | * @prot: new protection bits of the range | |
150 | * @pgoff: to be mapped page of the backing store file | |
151 | * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO. | |
152 | * | |
153 | * this syscall works purely via pagetables, so it's the most efficient | |
154 | * way to map the same (large) file into a given virtual window. Unlike | |
155 | * mmap()/mremap() it does not create any new vmas. The new mappings are | |
156 | * also safe across swapout. | |
157 | * | |
158 | * NOTE: the 'prot' parameter right now is ignored, and the vma's default | |
159 | * protection is used. Arbitrary protections might be implemented in the | |
160 | * future. | |
161 | */ | |
162 | asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size, | |
163 | unsigned long __prot, unsigned long pgoff, unsigned long flags) | |
164 | { | |
165 | struct mm_struct *mm = current->mm; | |
166 | struct address_space *mapping; | |
167 | unsigned long end = start + size; | |
168 | struct vm_area_struct *vma; | |
169 | int err = -EINVAL; | |
170 | int has_write_lock = 0; | |
171 | ||
172 | if (__prot) | |
173 | return err; | |
174 | /* | |
175 | * Sanitize the syscall parameters: | |
176 | */ | |
177 | start = start & PAGE_MASK; | |
178 | size = size & PAGE_MASK; | |
179 | ||
180 | /* Does the address range wrap, or is the span zero-sized? */ | |
181 | if (start + size <= start) | |
182 | return err; | |
183 | ||
184 | /* Can we represent this offset inside this architecture's pte's? */ | |
185 | #if PTE_FILE_MAX_BITS < BITS_PER_LONG | |
186 | if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS)) | |
187 | return err; | |
188 | #endif | |
189 | ||
190 | /* We need down_write() to change vma->vm_flags. */ | |
191 | down_read(&mm->mmap_sem); | |
192 | retry: | |
193 | vma = find_vma(mm, start); | |
194 | ||
195 | /* | |
196 | * Make sure the vma is shared, that it supports prefaulting, | |
197 | * and that the remapped range is valid and fully within | |
198 | * the single existing vma. vm_private_data is used as a | |
101d2be7 | 199 | * swapout cursor in a VM_NONLINEAR vma. |
1da177e4 LT |
200 | */ |
201 | if (vma && (vma->vm_flags & VM_SHARED) && | |
101d2be7 | 202 | (!vma->vm_private_data || (vma->vm_flags & VM_NONLINEAR)) && |
1da177e4 LT |
203 | vma->vm_ops && vma->vm_ops->populate && |
204 | end > start && start >= vma->vm_start && | |
205 | end <= vma->vm_end) { | |
206 | ||
207 | /* Must set VM_NONLINEAR before any pages are populated. */ | |
208 | if (pgoff != linear_page_index(vma, start) && | |
209 | !(vma->vm_flags & VM_NONLINEAR)) { | |
210 | if (!has_write_lock) { | |
211 | up_read(&mm->mmap_sem); | |
212 | down_write(&mm->mmap_sem); | |
213 | has_write_lock = 1; | |
214 | goto retry; | |
215 | } | |
216 | mapping = vma->vm_file->f_mapping; | |
217 | spin_lock(&mapping->i_mmap_lock); | |
218 | flush_dcache_mmap_lock(mapping); | |
219 | vma->vm_flags |= VM_NONLINEAR; | |
220 | vma_prio_tree_remove(vma, &mapping->i_mmap); | |
221 | vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); | |
222 | flush_dcache_mmap_unlock(mapping); | |
223 | spin_unlock(&mapping->i_mmap_lock); | |
224 | } | |
225 | ||
226 | err = vma->vm_ops->populate(vma, start, size, | |
227 | vma->vm_page_prot, | |
228 | pgoff, flags & MAP_NONBLOCK); | |
229 | ||
230 | /* | |
231 | * We can't clear VM_NONLINEAR because we'd have to do | |
232 | * it after ->populate completes, and that would prevent | |
233 | * downgrading the lock. (Locks can't be upgraded). | |
234 | */ | |
235 | } | |
236 | if (likely(!has_write_lock)) | |
237 | up_read(&mm->mmap_sem); | |
238 | else | |
239 | up_write(&mm->mmap_sem); | |
240 | ||
241 | return err; | |
242 | } | |
243 |