Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/mm/fremap.c
Parent Directory | Revision Log
Revision 630 -
(show annotations)
(download)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 6474 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 6474 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | |
23 | static inline void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma, |
24 | unsigned long addr, pte_t *ptep) |
25 | { |
26 | pte_t pte = *ptep; |
27 | |
28 | if (pte_none(pte)) |
29 | return; |
30 | if (pte_present(pte)) { |
31 | unsigned long pfn = pte_pfn(pte); |
32 | |
33 | flush_cache_page(vma, addr, pfn); |
34 | pte = ptep_clear_flush(vma, addr, ptep); |
35 | if (pfn_valid(pfn)) { |
36 | struct page *page = pfn_to_page(pfn); |
37 | if (!PageReserved(page)) { |
38 | if (pte_dirty(pte)) |
39 | set_page_dirty(page); |
40 | page_remove_rmap(page); |
41 | page_cache_release(page); |
42 | dec_mm_counter(mm, rss); |
43 | } |
44 | } |
45 | } else { |
46 | if (!pte_file(pte)) |
47 | free_swap_and_cache(pte_to_swp_entry(pte)); |
48 | pte_clear(mm, addr, ptep); |
49 | } |
50 | } |
51 | |
52 | /* |
53 | * Install a file page to a given virtual memory address, release any |
54 | * previously existing mapping. |
55 | */ |
56 | int install_page(struct mm_struct *mm, struct vm_area_struct *vma, |
57 | unsigned long addr, struct page *page, pgprot_t prot) |
58 | { |
59 | struct inode *inode; |
60 | pgoff_t size; |
61 | int err = -ENOMEM; |
62 | pte_t *pte; |
63 | pmd_t *pmd; |
64 | pud_t *pud; |
65 | pgd_t *pgd; |
66 | pte_t pte_val; |
67 | |
68 | pgd = pgd_offset(mm, addr); |
69 | spin_lock(&mm->page_table_lock); |
70 | |
71 | pud = pud_alloc(mm, pgd, addr); |
72 | if (!pud) |
73 | goto err_unlock; |
74 | |
75 | pmd = pmd_alloc(mm, pud, addr); |
76 | if (!pmd) |
77 | goto err_unlock; |
78 | |
79 | pte = pte_alloc_map(mm, pmd, addr); |
80 | if (!pte) |
81 | goto err_unlock; |
82 | |
83 | /* |
84 | * This page may have been truncated. Tell the |
85 | * caller about it. |
86 | */ |
87 | err = -EINVAL; |
88 | inode = vma->vm_file->f_mapping->host; |
89 | size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
90 | if (!page->mapping || page->index >= size) |
91 | goto err_unlock; |
92 | |
93 | zap_pte(mm, vma, addr, pte); |
94 | |
95 | inc_mm_counter(mm,rss); |
96 | flush_icache_page(vma, page); |
97 | set_pte_at(mm, addr, pte, mk_pte(page, prot)); |
98 | page_add_file_rmap(page); |
99 | pte_val = *pte; |
100 | pte_unmap(pte); |
101 | update_mmu_cache(vma, addr, pte_val); |
102 | |
103 | err = 0; |
104 | err_unlock: |
105 | spin_unlock(&mm->page_table_lock); |
106 | return err; |
107 | } |
108 | EXPORT_SYMBOL(install_page); |
109 | |
110 | |
111 | /* |
112 | * Install a file pte to a given virtual memory address, release any |
113 | * previously existing mapping. |
114 | */ |
115 | int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, |
116 | unsigned long addr, unsigned long pgoff, pgprot_t prot) |
117 | { |
118 | int err = -ENOMEM; |
119 | pte_t *pte; |
120 | pmd_t *pmd; |
121 | pud_t *pud; |
122 | pgd_t *pgd; |
123 | pte_t pte_val; |
124 | |
125 | pgd = pgd_offset(mm, addr); |
126 | spin_lock(&mm->page_table_lock); |
127 | |
128 | pud = pud_alloc(mm, pgd, addr); |
129 | if (!pud) |
130 | goto err_unlock; |
131 | |
132 | pmd = pmd_alloc(mm, pud, addr); |
133 | if (!pmd) |
134 | goto err_unlock; |
135 | |
136 | pte = pte_alloc_map(mm, pmd, addr); |
137 | if (!pte) |
138 | goto err_unlock; |
139 | |
140 | zap_pte(mm, vma, addr, pte); |
141 | |
142 | set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff)); |
143 | pte_val = *pte; |
144 | pte_unmap(pte); |
145 | update_mmu_cache(vma, addr, pte_val); |
146 | spin_unlock(&mm->page_table_lock); |
147 | return 0; |
148 | |
149 | err_unlock: |
150 | spin_unlock(&mm->page_table_lock); |
151 | return err; |
152 | } |
153 | |
154 | |
155 | /*** |
156 | * sys_remap_file_pages - remap arbitrary pages of a shared backing store |
157 | * file within an existing vma. |
158 | * @start: start of the remapped virtual memory range |
159 | * @size: size of the remapped virtual memory range |
160 | * @prot: new protection bits of the range |
161 | * @pgoff: to be mapped page of the backing store file |
162 | * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO. |
163 | * |
164 | * this syscall works purely via pagetables, so it's the most efficient |
165 | * way to map the same (large) file into a given virtual window. Unlike |
166 | * mmap()/mremap() it does not create any new vmas. The new mappings are |
167 | * also safe across swapout. |
168 | * |
169 | * NOTE: the 'prot' parameter right now is ignored, and the vma's default |
170 | * protection is used. Arbitrary protections might be implemented in the |
171 | * future. |
172 | */ |
173 | asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size, |
174 | unsigned long __prot, unsigned long pgoff, unsigned long flags) |
175 | { |
176 | struct mm_struct *mm = current->mm; |
177 | struct address_space *mapping; |
178 | unsigned long end = start + size; |
179 | struct vm_area_struct *vma; |
180 | int err = -EINVAL; |
181 | int has_write_lock = 0; |
182 | |
183 | if (__prot) |
184 | return err; |
185 | /* |
186 | * Sanitize the syscall parameters: |
187 | */ |
188 | start = start & PAGE_MASK; |
189 | size = size & PAGE_MASK; |
190 | |
191 | /* Does the address range wrap, or is the span zero-sized? */ |
192 | if (start + size <= start) |
193 | return err; |
194 | |
195 | /* Can we represent this offset inside this architecture's pte's? */ |
196 | #if PTE_FILE_MAX_BITS < BITS_PER_LONG |
197 | if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS)) |
198 | return err; |
199 | #endif |
200 | |
201 | /* We need down_write() to change vma->vm_flags. */ |
202 | down_read(&mm->mmap_sem); |
203 | retry: |
204 | vma = find_vma(mm, start); |
205 | |
206 | /* |
207 | * Make sure the vma is shared, that it supports prefaulting, |
208 | * and that the remapped range is valid and fully within |
209 | * the single existing vma. vm_private_data is used as a |
210 | * swapout cursor in a VM_NONLINEAR vma (unless VM_RESERVED |
211 | * or VM_LOCKED, but VM_LOCKED could be revoked later on). |
212 | */ |
213 | if (vma && (vma->vm_flags & VM_SHARED) && |
214 | (!vma->vm_private_data || |
215 | (vma->vm_flags & (VM_NONLINEAR|VM_RESERVED))) && |
216 | vma->vm_ops && vma->vm_ops->populate && |
217 | end > start && start >= vma->vm_start && |
218 | end <= vma->vm_end) { |
219 | |
220 | /* Must set VM_NONLINEAR before any pages are populated. */ |
221 | if (pgoff != linear_page_index(vma, start) && |
222 | !(vma->vm_flags & VM_NONLINEAR)) { |
223 | if (!has_write_lock) { |
224 | up_read(&mm->mmap_sem); |
225 | down_write(&mm->mmap_sem); |
226 | has_write_lock = 1; |
227 | goto retry; |
228 | } |
229 | mapping = vma->vm_file->f_mapping; |
230 | spin_lock(&mapping->i_mmap_lock); |
231 | flush_dcache_mmap_lock(mapping); |
232 | vma->vm_flags |= VM_NONLINEAR; |
233 | vma_prio_tree_remove(vma, &mapping->i_mmap); |
234 | vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); |
235 | flush_dcache_mmap_unlock(mapping); |
236 | spin_unlock(&mapping->i_mmap_lock); |
237 | } |
238 | |
239 | err = vma->vm_ops->populate(vma, start, size, |
240 | vma->vm_page_prot, |
241 | pgoff, flags & MAP_NONBLOCK); |
242 | |
243 | /* |
244 | * We can't clear VM_NONLINEAR because we'd have to do |
245 | * it after ->populate completes, and that would prevent |
246 | * downgrading the lock. (Locks can't be upgraded). |
247 | */ |
248 | } |
249 | if (likely(!has_write_lock)) |
250 | up_read(&mm->mmap_sem); |
251 | else |
252 | up_write(&mm->mmap_sem); |
253 | |
254 | return err; |
255 | } |
256 |