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8#include <linux/backing-dev.h>
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#include <linux/mmu_notifier.h>
19
20#include <asm/mmu_context.h>
21#include <asm/cacheflush.h>
22#include <asm/tlbflush.h>
23
24#include "internal.h"
25
26static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
27 unsigned long addr, pte_t *ptep)
28{
29 pte_t pte = *ptep;
30
31 if (pte_present(pte)) {
32 struct page *page;
33
34 flush_cache_page(vma, addr, pte_pfn(pte));
35 pte = ptep_clear_flush(vma, addr, ptep);
36 page = vm_normal_page(vma, addr, pte);
37 if (page) {
38 if (pte_dirty(pte))
39 set_page_dirty(page);
40 page_remove_rmap(page);
41 page_cache_release(page);
42 update_hiwater_rss(mm);
43 dec_mm_counter(mm, file_rss);
44 }
45 } else {
46 if (!pte_file(pte))
47 free_swap_and_cache(pte_to_swp_entry(pte));
48 pte_clear_not_present_full(mm, addr, ptep, 0);
49 }
50}
51
52
53
54
55
56static int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
57 unsigned long addr, unsigned long pgoff, pgprot_t prot)
58{
59 int err = -ENOMEM;
60 pte_t *pte;
61 spinlock_t *ptl;
62
63 pte = get_locked_pte(mm, addr, &ptl);
64 if (!pte)
65 goto out;
66
67 if (!pte_none(*pte))
68 zap_pte(mm, vma, addr, pte);
69
70 set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
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77
78 pte_unmap_unlock(pte, ptl);
79 err = 0;
80out:
81 return err;
82}
83
84static int populate_range(struct mm_struct *mm, struct vm_area_struct *vma,
85 unsigned long addr, unsigned long size, pgoff_t pgoff)
86{
87 int err;
88
89 do {
90 err = install_file_pte(mm, vma, addr, pgoff, vma->vm_page_prot);
91 if (err)
92 return err;
93
94 size -= PAGE_SIZE;
95 addr += PAGE_SIZE;
96 pgoff++;
97 } while (size);
98
99 return 0;
100
101}
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122
123SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
124 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
125{
126 struct mm_struct *mm = current->mm;
127 struct address_space *mapping;
128 unsigned long end = start + size;
129 struct vm_area_struct *vma;
130 int err = -EINVAL;
131 int has_write_lock = 0;
132
133 if (prot)
134 return err;
135
136
137
138 start = start & PAGE_MASK;
139 size = size & PAGE_MASK;
140
141
142 if (start + size <= start)
143 return err;
144
145
146#if PTE_FILE_MAX_BITS < BITS_PER_LONG
147 if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
148 return err;
149#endif
150
151
152 down_read(&mm->mmap_sem);
153 retry:
154 vma = find_vma(mm, start);
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161
162 if (!vma || !(vma->vm_flags & VM_SHARED))
163 goto out;
164
165 if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR))
166 goto out;
167
168 if (!(vma->vm_flags & VM_CAN_NONLINEAR))
169 goto out;
170
171 if (end <= start || start < vma->vm_start || end > vma->vm_end)
172 goto out;
173
174
175 if (!(vma->vm_flags & VM_NONLINEAR)) {
176
177 if (pgoff == linear_page_index(vma, start)) {
178 err = 0;
179 goto out;
180 }
181
182 if (!has_write_lock) {
183 up_read(&mm->mmap_sem);
184 down_write(&mm->mmap_sem);
185 has_write_lock = 1;
186 goto retry;
187 }
188 mapping = vma->vm_file->f_mapping;
189
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193
194 if (mapping_cap_account_dirty(mapping)) {
195 unsigned long addr;
196 struct file *file = vma->vm_file;
197
198 flags &= MAP_NONBLOCK;
199 get_file(file);
200 addr = mmap_region(file, start, size,
201 flags, vma->vm_flags, pgoff);
202 fput(file);
203 if (IS_ERR_VALUE(addr)) {
204 err = addr;
205 } else {
206 BUG_ON(addr != start);
207 err = 0;
208 }
209 goto out;
210 }
211 spin_lock(&mapping->i_mmap_lock);
212 flush_dcache_mmap_lock(mapping);
213 vma->vm_flags |= VM_NONLINEAR;
214 vma_prio_tree_remove(vma, &mapping->i_mmap);
215 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
216 flush_dcache_mmap_unlock(mapping);
217 spin_unlock(&mapping->i_mmap_lock);
218 }
219
220 if (vma->vm_flags & VM_LOCKED) {
221
222
223
224 unsigned int saved_flags = vma->vm_flags;
225 munlock_vma_pages_range(vma, start, start + size);
226 vma->vm_flags = saved_flags;
227 }
228
229 mmu_notifier_invalidate_range_start(mm, start, start + size);
230 err = populate_range(mm, vma, start, size, pgoff);
231 mmu_notifier_invalidate_range_end(mm, start, start + size);
232 if (!err && !(flags & MAP_NONBLOCK)) {
233 if (vma->vm_flags & VM_LOCKED) {
234
235
236
237 mlock_vma_pages_range(vma, start, start + size);
238 } else {
239 if (unlikely(has_write_lock)) {
240 downgrade_write(&mm->mmap_sem);
241 has_write_lock = 0;
242 }
243 make_pages_present(start, start+size);
244 }
245 }
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252
253out:
254 if (likely(!has_write_lock))
255 up_read(&mm->mmap_sem);
256 else
257 up_write(&mm->mmap_sem);
258
259 return err;
260}
261