wireless: only use alpha2 regulatory information from country IE
[linux-2.6.git] / mm / fremap.c
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 #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
26 static 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, MM_FILEPAGES);
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  * Install a file pte to a given virtual memory address, release any
54  * previously existing mapping.
55  */
56 static 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));
71         /*
72          * We don't need to run update_mmu_cache() here because the "file pte"
73          * being installed by install_file_pte() is not a real pte - it's a
74          * non-present entry (like a swap entry), noting what file offset should
75          * be mapped there when there's a fault (in a non-linear vma where
76          * that's not obvious).
77          */
78         pte_unmap_unlock(pte, ptl);
79         err = 0;
80 out:
81         return err;
82 }
83
84 static 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 }
102
103 /**
104  * sys_remap_file_pages - remap arbitrary pages of an existing VM_SHARED vma
105  * @start: start of the remapped virtual memory range
106  * @size: size of the remapped virtual memory range
107  * @prot: new protection bits of the range (see NOTE)
108  * @pgoff: to-be-mapped page of the backing store file
109  * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
110  *
111  * sys_remap_file_pages remaps arbitrary pages of an existing VM_SHARED vma
112  * (shared backing store file).
113  *
114  * This syscall works purely via pagetables, so it's the most efficient
115  * way to map the same (large) file into a given virtual window. Unlike
116  * mmap()/mremap() it does not create any new vmas. The new mappings are
117  * also safe across swapout.
118  *
119  * NOTE: the @prot parameter right now is ignored (but must be zero),
120  * and the vma's default protection is used. Arbitrary protections
121  * might be implemented in the future.
122  */
123 SYSCALL_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          * Sanitize the syscall parameters:
137          */
138         start = start & PAGE_MASK;
139         size = size & PAGE_MASK;
140
141         /* Does the address range wrap, or is the span zero-sized? */
142         if (start + size <= start)
143                 return err;
144
145         /* Can we represent this offset inside this architecture's pte's? */
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         /* We need down_write() to change vma->vm_flags. */
152         down_read(&mm->mmap_sem);
153  retry:
154         vma = find_vma(mm, start);
155
156         /*
157          * Make sure the vma is shared, that it supports prefaulting,
158          * and that the remapped range is valid and fully within
159          * the single existing vma.  vm_private_data is used as a
160          * swapout cursor in a VM_NONLINEAR vma.
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         /* Must set VM_NONLINEAR before any pages are populated. */
175         if (!(vma->vm_flags & VM_NONLINEAR)) {
176                 /* Don't need a nonlinear mapping, exit success */
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                 /*
190                  * page_mkclean doesn't work on nonlinear vmas, so if
191                  * dirty pages need to be accounted, emulate with linear
192                  * vmas.
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                  * drop PG_Mlocked flag for over-mapped range
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                          * might be mapping previously unmapped range of file
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         }
246
247         /*
248          * We can't clear VM_NONLINEAR because we'd have to do
249          * it after ->populate completes, and that would prevent
250          * downgrading the lock.  (Locks can't be upgraded).
251          */
252
253 out:
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 }