ia64/linux-2.6.18-xen.hg

view mm/fremap.c @ 871:9cbcc9008446

xen/x86: don't initialize cpu_data[]'s apicid field on generic code

Afaict, this is not only redundant with the intialization done in
drivers/xen/core/smpboot.c, but actually results - at least for
secondary CPUs - in the Xen-specific value written to be later
overwritten with whatever the generic code determines (with no
guarantee that the two values are identical).

Signed-off-by: Jan Beulich <jbeulich@novell.com>
author Keir Fraser <keir.fraser@citrix.com>
date Thu May 14 10:09:15 2009 +0100 (2009-05-14)
parents 831230e53067
children
line source
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 */
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>
19 #include <asm/mmu_context.h>
20 #include <asm/cacheflush.h>
21 #include <asm/tlbflush.h>
23 static int 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 struct page *page = NULL;
29 if (pte_present(pte)) {
30 flush_cache_page(vma, addr, pte_pfn(pte));
31 pte = ptep_clear_flush(vma, addr, ptep);
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);
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 }
44 return !!page;
45 }
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 pte_t pte_val;
59 spinlock_t *ptl;
61 pte = get_locked_pte(mm, addr, &ptl);
62 if (!pte)
63 goto out;
65 /*
66 * This page may have been truncated. Tell the
67 * caller about it.
68 */
69 err = -EINVAL;
70 inode = vma->vm_file->f_mapping->host;
71 size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
72 if (!page->mapping || page->index >= size)
73 goto unlock;
74 err = -ENOMEM;
75 if (page_mapcount(page) > INT_MAX/2)
76 goto unlock;
78 if (pte_none(*pte) || !zap_pte(mm, vma, addr, pte))
79 inc_mm_counter(mm, file_rss);
81 flush_icache_page(vma, page);
82 set_pte_at(mm, addr, pte, mk_pte(page, prot));
83 page_add_file_rmap(page);
84 pte_val = *pte;
85 update_mmu_cache(vma, addr, pte_val);
86 lazy_mmu_prot_update(pte_val);
87 err = 0;
88 unlock:
89 pte_unmap_unlock(pte, ptl);
90 out:
91 return err;
92 }
93 EXPORT_SYMBOL(install_page);
95 /*
96 * Install a file pte to a given virtual memory address, release any
97 * previously existing mapping.
98 */
99 int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma,
100 unsigned long addr, unsigned long pgoff, pgprot_t prot)
101 {
102 int err = -ENOMEM;
103 pte_t *pte;
104 pte_t pte_val;
105 spinlock_t *ptl;
107 pte = get_locked_pte(mm, addr, &ptl);
108 if (!pte)
109 goto out;
111 if (!pte_none(*pte) && zap_pte(mm, vma, addr, pte)) {
112 update_hiwater_rss(mm);
113 dec_mm_counter(mm, file_rss);
114 }
116 set_pte_at(mm, addr, pte, pgoff_to_pte(pgoff));
117 pte_val = *pte;
118 /*
119 * We don't need to run update_mmu_cache() here because the "file pte"
120 * being installed by install_file_pte() is not a real pte - it's a
121 * non-present entry (like a swap entry), noting what file offset should
122 * be mapped there when there's a fault (in a non-linear vma where
123 * that's not obvious).
124 */
125 pte_unmap_unlock(pte, ptl);
126 err = 0;
127 out:
128 return err;
129 }
131 /***
132 * sys_remap_file_pages - remap arbitrary pages of a shared backing store
133 * file within an existing vma.
134 * @start: start of the remapped virtual memory range
135 * @size: size of the remapped virtual memory range
136 * @prot: new protection bits of the range
137 * @pgoff: to be mapped page of the backing store file
138 * @flags: 0 or MAP_NONBLOCKED - the later will cause no IO.
139 *
140 * this syscall works purely via pagetables, so it's the most efficient
141 * way to map the same (large) file into a given virtual window. Unlike
142 * mmap()/mremap() it does not create any new vmas. The new mappings are
143 * also safe across swapout.
144 *
145 * NOTE: the 'prot' parameter right now is ignored, and the vma's default
146 * protection is used. Arbitrary protections might be implemented in the
147 * future.
148 */
149 asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
150 unsigned long __prot, unsigned long pgoff, unsigned long flags)
151 {
152 struct mm_struct *mm = current->mm;
153 struct address_space *mapping;
154 unsigned long end = start + size;
155 struct vm_area_struct *vma;
156 int err = -EINVAL;
157 int has_write_lock = 0;
159 if (__prot)
160 return err;
161 /*
162 * Sanitize the syscall parameters:
163 */
164 start = start & PAGE_MASK;
165 size = size & PAGE_MASK;
167 /* Does the address range wrap, or is the span zero-sized? */
168 if (start + size <= start)
169 return err;
171 /* Can we represent this offset inside this architecture's pte's? */
172 #if PTE_FILE_MAX_BITS < BITS_PER_LONG
173 if (pgoff + (size >> PAGE_SHIFT) >= (1UL << PTE_FILE_MAX_BITS))
174 return err;
175 #endif
177 /* We need down_write() to change vma->vm_flags. */
178 down_read(&mm->mmap_sem);
179 retry:
180 vma = find_vma(mm, start);
182 /*
183 * Make sure the vma is shared, that it supports prefaulting,
184 * and that the remapped range is valid and fully within
185 * the single existing vma. vm_private_data is used as a
186 * swapout cursor in a VM_NONLINEAR vma.
187 */
188 if (vma && (vma->vm_flags & VM_SHARED) &&
189 (!vma->vm_private_data || (vma->vm_flags & VM_NONLINEAR)) &&
190 vma->vm_ops && vma->vm_ops->populate &&
191 end > start && start >= vma->vm_start &&
192 end <= vma->vm_end) {
194 /* Must set VM_NONLINEAR before any pages are populated. */
195 if (pgoff != linear_page_index(vma, start) &&
196 !(vma->vm_flags & VM_NONLINEAR)) {
197 if (!has_write_lock) {
198 up_read(&mm->mmap_sem);
199 down_write(&mm->mmap_sem);
200 has_write_lock = 1;
201 goto retry;
202 }
203 mapping = vma->vm_file->f_mapping;
204 spin_lock(&mapping->i_mmap_lock);
205 flush_dcache_mmap_lock(mapping);
206 vma->vm_flags |= VM_NONLINEAR;
207 vma_prio_tree_remove(vma, &mapping->i_mmap);
208 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
209 flush_dcache_mmap_unlock(mapping);
210 spin_unlock(&mapping->i_mmap_lock);
211 }
213 err = vma->vm_ops->populate(vma, start, size,
214 vma->vm_page_prot,
215 pgoff, flags & MAP_NONBLOCK);
217 /*
218 * We can't clear VM_NONLINEAR because we'd have to do
219 * it after ->populate completes, and that would prevent
220 * downgrading the lock. (Locks can't be upgraded).
221 */
222 }
223 if (likely(!has_write_lock))
224 up_read(&mm->mmap_sem);
225 else
226 up_write(&mm->mmap_sem);
228 return err;
229 }