staging: iio: dac: Use spi_write() and handle return value
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / fremap.c
blobec520c7b28dffedb5027de6b27834831938671cd
1 /*
2 * linux/mm/fremap.c
3 *
4 * Explicit pagetable population and nonlinear (random) mappings support.
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>
20 #include <asm/mmu_context.h>
21 #include <asm/cacheflush.h>
22 #include <asm/tlbflush.h>
24 #include "internal.h"
26 static void zap_pte(struct mm_struct *mm, struct vm_area_struct *vma,
27 unsigned long addr, pte_t *ptep)
29 pte_t pte = *ptep;
31 if (pte_present(pte)) {
32 struct page *page;
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);
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);
53 * Install a file pte to a given virtual memory address, release any
54 * previously existing mapping.
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)
59 int err = -ENOMEM;
60 pte_t *pte;
61 spinlock_t *ptl;
63 pte = get_locked_pte(mm, addr, &ptl);
64 if (!pte)
65 goto out;
67 if (!pte_none(*pte))
68 zap_pte(mm, vma, addr, pte);
70 set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
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).
78 pte_unmap_unlock(pte, ptl);
79 err = 0;
80 out:
81 return err;
84 static int populate_range(struct mm_struct *mm, struct vm_area_struct *vma,
85 unsigned long addr, unsigned long size, pgoff_t pgoff)
87 int err;
89 do {
90 err = install_file_pte(mm, vma, addr, pgoff, vma->vm_page_prot);
91 if (err)
92 return err;
94 size -= PAGE_SIZE;
95 addr += PAGE_SIZE;
96 pgoff++;
97 } while (size);
99 return 0;
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.
111 * sys_remap_file_pages remaps arbitrary pages of an existing VM_SHARED vma
112 * (shared backing store file).
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.
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.
123 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
124 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
126 struct mm_struct *mm = current->mm;
127 struct address_space *mapping;
128 struct vm_area_struct *vma;
129 int err = -EINVAL;
130 int has_write_lock = 0;
132 if (prot)
133 return err;
135 * Sanitize the syscall parameters:
137 start = start & PAGE_MASK;
138 size = size & PAGE_MASK;
140 /* Does the address range wrap, or is the span zero-sized? */
141 if (start + size <= start)
142 return err;
144 /* Does pgoff wrap? */
145 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
146 return err;
148 /* Can we represent this offset inside this architecture's pte's? */
149 #if PTE_FILE_MAX_BITS < BITS_PER_LONG
150 if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
151 return err;
152 #endif
154 /* We need down_write() to change vma->vm_flags. */
155 down_read(&mm->mmap_sem);
156 retry:
157 vma = find_vma(mm, start);
160 * Make sure the vma is shared, that it supports prefaulting,
161 * and that the remapped range is valid and fully within
162 * the single existing vma. vm_private_data is used as a
163 * swapout cursor in a VM_NONLINEAR vma.
165 if (!vma || !(vma->vm_flags & VM_SHARED))
166 goto out;
168 if (vma->vm_private_data && !(vma->vm_flags & VM_NONLINEAR))
169 goto out;
171 if (!(vma->vm_flags & VM_CAN_NONLINEAR))
172 goto out;
174 if (start < vma->vm_start || start + size > vma->vm_end)
175 goto out;
177 /* Must set VM_NONLINEAR before any pages are populated. */
178 if (!(vma->vm_flags & VM_NONLINEAR)) {
179 /* Don't need a nonlinear mapping, exit success */
180 if (pgoff == linear_page_index(vma, start)) {
181 err = 0;
182 goto out;
185 if (!has_write_lock) {
186 up_read(&mm->mmap_sem);
187 down_write(&mm->mmap_sem);
188 has_write_lock = 1;
189 goto retry;
191 mapping = vma->vm_file->f_mapping;
193 * page_mkclean doesn't work on nonlinear vmas, so if
194 * dirty pages need to be accounted, emulate with linear
195 * vmas.
197 if (mapping_cap_account_dirty(mapping)) {
198 unsigned long addr;
199 struct file *file = vma->vm_file;
201 flags &= MAP_NONBLOCK;
202 get_file(file);
203 addr = mmap_region(file, start, size,
204 flags, vma->vm_flags, pgoff);
205 fput(file);
206 if (IS_ERR_VALUE(addr)) {
207 err = addr;
208 } else {
209 BUG_ON(addr != start);
210 err = 0;
212 goto out;
214 spin_lock(&mapping->i_mmap_lock);
215 flush_dcache_mmap_lock(mapping);
216 vma->vm_flags |= VM_NONLINEAR;
217 vma_prio_tree_remove(vma, &mapping->i_mmap);
218 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
219 flush_dcache_mmap_unlock(mapping);
220 spin_unlock(&mapping->i_mmap_lock);
223 if (vma->vm_flags & VM_LOCKED) {
225 * drop PG_Mlocked flag for over-mapped range
227 unsigned int saved_flags = vma->vm_flags;
228 munlock_vma_pages_range(vma, start, start + size);
229 vma->vm_flags = saved_flags;
232 mmu_notifier_invalidate_range_start(mm, start, start + size);
233 err = populate_range(mm, vma, start, size, pgoff);
234 mmu_notifier_invalidate_range_end(mm, start, start + size);
235 if (!err && !(flags & MAP_NONBLOCK)) {
236 if (vma->vm_flags & VM_LOCKED) {
238 * might be mapping previously unmapped range of file
240 mlock_vma_pages_range(vma, start, start + size);
241 } else {
242 if (unlikely(has_write_lock)) {
243 downgrade_write(&mm->mmap_sem);
244 has_write_lock = 0;
246 make_pages_present(start, start+size);
251 * We can't clear VM_NONLINEAR because we'd have to do
252 * it after ->populate completes, and that would prevent
253 * downgrading the lock. (Locks can't be upgraded).
256 out:
257 if (likely(!has_write_lock))
258 up_read(&mm->mmap_sem);
259 else
260 up_write(&mm->mmap_sem);
262 return err;