Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * mm/mremap.c |
| 3 | * |
| 4 | * (C) Copyright 1996 Linus Torvalds |
| 5 | * |
Alan Cox | 046c688 | 2009-01-05 14:06:29 +0000 | [diff] [blame] | 6 | * Address space accounting code <alan@lxorguk.ukuu.org.uk> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | * (C) Copyright 2002 Red Hat Inc, All Rights Reserved |
| 8 | */ |
| 9 | |
| 10 | #include <linux/mm.h> |
| 11 | #include <linux/hugetlb.h> |
| 12 | #include <linux/slab.h> |
| 13 | #include <linux/shm.h> |
Hugh Dickins | 1ff8299 | 2009-09-21 17:02:05 -0700 | [diff] [blame] | 14 | #include <linux/ksm.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <linux/mman.h> |
| 16 | #include <linux/swap.h> |
Randy.Dunlap | c59ede7 | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 17 | #include <linux/capability.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | #include <linux/fs.h> |
| 19 | #include <linux/highmem.h> |
| 20 | #include <linux/security.h> |
| 21 | #include <linux/syscalls.h> |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 22 | #include <linux/mmu_notifier.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 23 | |
| 24 | #include <asm/uaccess.h> |
| 25 | #include <asm/cacheflush.h> |
| 26 | #include <asm/tlbflush.h> |
| 27 | |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 28 | #include "internal.h" |
| 29 | |
Al Viro | f106af4 | 2009-11-24 08:25:18 -0500 | [diff] [blame] | 30 | #ifndef arch_mmap_check |
| 31 | #define arch_mmap_check(addr, len, flags) (0) |
| 32 | #endif |
| 33 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 34 | static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | { |
| 36 | pgd_t *pgd; |
| 37 | pud_t *pud; |
| 38 | pmd_t *pmd; |
| 39 | |
| 40 | pgd = pgd_offset(mm, addr); |
| 41 | if (pgd_none_or_clear_bad(pgd)) |
| 42 | return NULL; |
| 43 | |
| 44 | pud = pud_offset(pgd, addr); |
| 45 | if (pud_none_or_clear_bad(pud)) |
| 46 | return NULL; |
| 47 | |
| 48 | pmd = pmd_offset(pud, addr); |
| 49 | if (pmd_none_or_clear_bad(pmd)) |
| 50 | return NULL; |
| 51 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 52 | return pmd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 53 | } |
| 54 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 55 | static pmd_t *alloc_new_pmd(struct mm_struct *mm, unsigned long addr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 56 | { |
| 57 | pgd_t *pgd; |
| 58 | pud_t *pud; |
Hugh Dickins | c74df32 | 2005-10-29 18:16:23 -0700 | [diff] [blame] | 59 | pmd_t *pmd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 60 | |
| 61 | pgd = pgd_offset(mm, addr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 62 | pud = pud_alloc(mm, pgd, addr); |
| 63 | if (!pud) |
Hugh Dickins | c74df32 | 2005-10-29 18:16:23 -0700 | [diff] [blame] | 64 | return NULL; |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 65 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 66 | pmd = pmd_alloc(mm, pud, addr); |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 67 | if (!pmd) |
Hugh Dickins | c74df32 | 2005-10-29 18:16:23 -0700 | [diff] [blame] | 68 | return NULL; |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 69 | |
Hugh Dickins | 1bb3630 | 2005-10-29 18:16:22 -0700 | [diff] [blame] | 70 | if (!pmd_present(*pmd) && __pte_alloc(mm, pmd, addr)) |
Hugh Dickins | c74df32 | 2005-10-29 18:16:23 -0700 | [diff] [blame] | 71 | return NULL; |
| 72 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 73 | return pmd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | } |
| 75 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 76 | static void move_ptes(struct vm_area_struct *vma, pmd_t *old_pmd, |
| 77 | unsigned long old_addr, unsigned long old_end, |
| 78 | struct vm_area_struct *new_vma, pmd_t *new_pmd, |
| 79 | unsigned long new_addr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 80 | { |
| 81 | struct address_space *mapping = NULL; |
| 82 | struct mm_struct *mm = vma->vm_mm; |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 83 | pte_t *old_pte, *new_pte, pte; |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 84 | spinlock_t *old_ptl, *new_ptl; |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 85 | unsigned long old_start; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 87 | old_start = old_addr; |
| 88 | mmu_notifier_invalidate_range_start(vma->vm_mm, |
| 89 | old_start, old_end); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 90 | if (vma->vm_file) { |
| 91 | /* |
| 92 | * Subtle point from Rajesh Venkatasubramanian: before |
npiggin@suse.de | 25d9e2d | 2009-08-21 02:35:05 +1000 | [diff] [blame] | 93 | * moving file-based ptes, we must lock truncate_pagecache |
| 94 | * out, since it might clean the dst vma before the src vma, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 95 | * and we propagate stale pages into the dst afterward. |
| 96 | */ |
| 97 | mapping = vma->vm_file->f_mapping; |
| 98 | spin_lock(&mapping->i_mmap_lock); |
| 99 | if (new_vma->vm_truncate_count && |
| 100 | new_vma->vm_truncate_count != vma->vm_truncate_count) |
| 101 | new_vma->vm_truncate_count = 0; |
| 102 | } |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 103 | |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 104 | /* |
| 105 | * We don't have to worry about the ordering of src and dst |
| 106 | * pte locks because exclusive mmap_sem prevents deadlock. |
| 107 | */ |
Hugh Dickins | c74df32 | 2005-10-29 18:16:23 -0700 | [diff] [blame] | 108 | old_pte = pte_offset_map_lock(mm, old_pmd, old_addr, &old_ptl); |
| 109 | new_pte = pte_offset_map_nested(new_pmd, new_addr); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 110 | new_ptl = pte_lockptr(mm, new_pmd); |
| 111 | if (new_ptl != old_ptl) |
Ingo Molnar | f20dc5f | 2006-07-03 00:25:08 -0700 | [diff] [blame] | 112 | spin_lock_nested(new_ptl, SINGLE_DEPTH_NESTING); |
Zachary Amsden | 6606c3e | 2006-09-30 23:29:33 -0700 | [diff] [blame] | 113 | arch_enter_lazy_mmu_mode(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 115 | for (; old_addr < old_end; old_pte++, old_addr += PAGE_SIZE, |
| 116 | new_pte++, new_addr += PAGE_SIZE) { |
| 117 | if (pte_none(*old_pte)) |
| 118 | continue; |
| 119 | pte = ptep_clear_flush(vma, old_addr, old_pte); |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 120 | pte = move_pte(pte, new_vma->vm_page_prot, old_addr, new_addr); |
| 121 | set_pte_at(mm, new_addr, new_pte, pte); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 122 | } |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 123 | |
Zachary Amsden | 6606c3e | 2006-09-30 23:29:33 -0700 | [diff] [blame] | 124 | arch_leave_lazy_mmu_mode(); |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 125 | if (new_ptl != old_ptl) |
| 126 | spin_unlock(new_ptl); |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 127 | pte_unmap_nested(new_pte - 1); |
Hugh Dickins | c74df32 | 2005-10-29 18:16:23 -0700 | [diff] [blame] | 128 | pte_unmap_unlock(old_pte - 1, old_ptl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | if (mapping) |
| 130 | spin_unlock(&mapping->i_mmap_lock); |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 131 | mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 132 | } |
| 133 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 134 | #define LATENCY_LIMIT (64 * PAGE_SIZE) |
| 135 | |
Ollie Wild | b6a2fea | 2007-07-19 01:48:16 -0700 | [diff] [blame] | 136 | unsigned long move_page_tables(struct vm_area_struct *vma, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 137 | unsigned long old_addr, struct vm_area_struct *new_vma, |
| 138 | unsigned long new_addr, unsigned long len) |
| 139 | { |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 140 | unsigned long extent, next, old_end; |
| 141 | pmd_t *old_pmd, *new_pmd; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 143 | old_end = old_addr + len; |
| 144 | flush_cache_range(vma, old_addr, old_end); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 145 | |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 146 | for (; old_addr < old_end; old_addr += extent, new_addr += extent) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 147 | cond_resched(); |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 148 | next = (old_addr + PMD_SIZE) & PMD_MASK; |
| 149 | if (next - 1 > old_end) |
| 150 | next = old_end; |
| 151 | extent = next - old_addr; |
| 152 | old_pmd = get_old_pmd(vma->vm_mm, old_addr); |
| 153 | if (!old_pmd) |
| 154 | continue; |
| 155 | new_pmd = alloc_new_pmd(vma->vm_mm, new_addr); |
| 156 | if (!new_pmd) |
| 157 | break; |
| 158 | next = (new_addr + PMD_SIZE) & PMD_MASK; |
| 159 | if (extent > next - new_addr) |
| 160 | extent = next - new_addr; |
| 161 | if (extent > LATENCY_LIMIT) |
| 162 | extent = LATENCY_LIMIT; |
| 163 | move_ptes(vma, old_pmd, old_addr, old_addr + extent, |
| 164 | new_vma, new_pmd, new_addr); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 165 | } |
Hugh Dickins | 7be7a54 | 2005-10-29 18:16:00 -0700 | [diff] [blame] | 166 | |
| 167 | return len + old_addr - old_end; /* how much done */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 168 | } |
| 169 | |
| 170 | static unsigned long move_vma(struct vm_area_struct *vma, |
| 171 | unsigned long old_addr, unsigned long old_len, |
| 172 | unsigned long new_len, unsigned long new_addr) |
| 173 | { |
| 174 | struct mm_struct *mm = vma->vm_mm; |
| 175 | struct vm_area_struct *new_vma; |
| 176 | unsigned long vm_flags = vma->vm_flags; |
| 177 | unsigned long new_pgoff; |
| 178 | unsigned long moved_len; |
| 179 | unsigned long excess = 0; |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 180 | unsigned long hiwater_vm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 181 | int split = 0; |
Hugh Dickins | 7103ad3 | 2009-09-21 17:02:28 -0700 | [diff] [blame] | 182 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 183 | |
| 184 | /* |
| 185 | * We'd prefer to avoid failure later on in do_munmap: |
| 186 | * which may split one vma into three before unmapping. |
| 187 | */ |
| 188 | if (mm->map_count >= sysctl_max_map_count - 3) |
| 189 | return -ENOMEM; |
| 190 | |
Hugh Dickins | 1ff8299 | 2009-09-21 17:02:05 -0700 | [diff] [blame] | 191 | /* |
| 192 | * Advise KSM to break any KSM pages in the area to be moved: |
| 193 | * it would be confusing if they were to turn up at the new |
| 194 | * location, where they happen to coincide with different KSM |
| 195 | * pages recently unmapped. But leave vma->vm_flags as it was, |
| 196 | * so KSM can come around to merge on vma and new_vma afterwards. |
| 197 | */ |
Hugh Dickins | 7103ad3 | 2009-09-21 17:02:28 -0700 | [diff] [blame] | 198 | err = ksm_madvise(vma, old_addr, old_addr + old_len, |
| 199 | MADV_UNMERGEABLE, &vm_flags); |
| 200 | if (err) |
| 201 | return err; |
Hugh Dickins | 1ff8299 | 2009-09-21 17:02:05 -0700 | [diff] [blame] | 202 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | new_pgoff = vma->vm_pgoff + ((old_addr - vma->vm_start) >> PAGE_SHIFT); |
| 204 | new_vma = copy_vma(&vma, new_addr, new_len, new_pgoff); |
| 205 | if (!new_vma) |
| 206 | return -ENOMEM; |
| 207 | |
| 208 | moved_len = move_page_tables(vma, old_addr, new_vma, new_addr, old_len); |
| 209 | if (moved_len < old_len) { |
| 210 | /* |
| 211 | * On error, move entries back from new area to old, |
| 212 | * which will succeed since page tables still there, |
| 213 | * and then proceed to unmap new area instead of old. |
| 214 | */ |
| 215 | move_page_tables(new_vma, new_addr, vma, old_addr, moved_len); |
| 216 | vma = new_vma; |
| 217 | old_len = new_len; |
| 218 | old_addr = new_addr; |
| 219 | new_addr = -ENOMEM; |
| 220 | } |
| 221 | |
| 222 | /* Conceal VM_ACCOUNT so old reservation is not undone */ |
| 223 | if (vm_flags & VM_ACCOUNT) { |
| 224 | vma->vm_flags &= ~VM_ACCOUNT; |
| 225 | excess = vma->vm_end - vma->vm_start - old_len; |
| 226 | if (old_addr > vma->vm_start && |
| 227 | old_addr + old_len < vma->vm_end) |
| 228 | split = 1; |
| 229 | } |
| 230 | |
Kirill Korotaev | 7179906 | 2005-05-16 21:53:18 -0700 | [diff] [blame] | 231 | /* |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 232 | * If we failed to move page tables we still do total_vm increment |
| 233 | * since do_munmap() will decrement it by old_len == new_len. |
| 234 | * |
| 235 | * Since total_vm is about to be raised artificially high for a |
| 236 | * moment, we need to restore high watermark afterwards: if stats |
| 237 | * are taken meanwhile, total_vm and hiwater_vm appear too high. |
| 238 | * If this were a serious issue, we'd add a flag to do_munmap(). |
Kirill Korotaev | 7179906 | 2005-05-16 21:53:18 -0700 | [diff] [blame] | 239 | */ |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 240 | hiwater_vm = mm->hiwater_vm; |
Kirill Korotaev | 7179906 | 2005-05-16 21:53:18 -0700 | [diff] [blame] | 241 | mm->total_vm += new_len >> PAGE_SHIFT; |
Hugh Dickins | ab50b8e | 2005-10-29 18:15:56 -0700 | [diff] [blame] | 242 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, new_len>>PAGE_SHIFT); |
Kirill Korotaev | 7179906 | 2005-05-16 21:53:18 -0700 | [diff] [blame] | 243 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | if (do_munmap(mm, old_addr, old_len) < 0) { |
| 245 | /* OOM: unable to split vma, just get accounts right */ |
| 246 | vm_unacct_memory(excess >> PAGE_SHIFT); |
| 247 | excess = 0; |
| 248 | } |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 249 | mm->hiwater_vm = hiwater_vm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 250 | |
| 251 | /* Restore VM_ACCOUNT if one or two pieces of vma left */ |
| 252 | if (excess) { |
| 253 | vma->vm_flags |= VM_ACCOUNT; |
| 254 | if (split) |
| 255 | vma->vm_next->vm_flags |= VM_ACCOUNT; |
| 256 | } |
| 257 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 258 | if (vm_flags & VM_LOCKED) { |
| 259 | mm->locked_vm += new_len >> PAGE_SHIFT; |
| 260 | if (new_len > old_len) |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 261 | mlock_vma_pages_range(new_vma, new_addr + old_len, |
| 262 | new_addr + new_len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 263 | } |
| 264 | |
| 265 | return new_addr; |
| 266 | } |
| 267 | |
Al Viro | 54f5de7 | 2009-11-24 07:17:46 -0500 | [diff] [blame] | 268 | static struct vm_area_struct *vma_to_resize(unsigned long addr, |
| 269 | unsigned long old_len, unsigned long new_len, unsigned long *p) |
| 270 | { |
| 271 | struct mm_struct *mm = current->mm; |
| 272 | struct vm_area_struct *vma = find_vma(mm, addr); |
| 273 | |
| 274 | if (!vma || vma->vm_start > addr) |
| 275 | goto Efault; |
| 276 | |
| 277 | if (is_vm_hugetlb_page(vma)) |
| 278 | goto Einval; |
| 279 | |
| 280 | /* We can't remap across vm area boundaries */ |
| 281 | if (old_len > vma->vm_end - addr) |
| 282 | goto Efault; |
| 283 | |
| 284 | if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) { |
| 285 | if (new_len > old_len) |
| 286 | goto Efault; |
| 287 | } |
| 288 | |
| 289 | if (vma->vm_flags & VM_LOCKED) { |
| 290 | unsigned long locked, lock_limit; |
| 291 | locked = mm->locked_vm << PAGE_SHIFT; |
| 292 | lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; |
| 293 | locked += new_len - old_len; |
| 294 | if (locked > lock_limit && !capable(CAP_IPC_LOCK)) |
| 295 | goto Eagain; |
| 296 | } |
| 297 | |
| 298 | if (!may_expand_vm(mm, (new_len - old_len) >> PAGE_SHIFT)) |
| 299 | goto Enomem; |
| 300 | |
| 301 | if (vma->vm_flags & VM_ACCOUNT) { |
| 302 | unsigned long charged = (new_len - old_len) >> PAGE_SHIFT; |
| 303 | if (security_vm_enough_memory(charged)) |
| 304 | goto Efault; |
| 305 | *p = charged; |
| 306 | } |
| 307 | |
| 308 | return vma; |
| 309 | |
| 310 | Efault: /* very odd choice for most of the cases, but... */ |
| 311 | return ERR_PTR(-EFAULT); |
| 312 | Einval: |
| 313 | return ERR_PTR(-EINVAL); |
| 314 | Enomem: |
| 315 | return ERR_PTR(-ENOMEM); |
| 316 | Eagain: |
| 317 | return ERR_PTR(-EAGAIN); |
| 318 | } |
| 319 | |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 320 | static unsigned long mremap_to(unsigned long addr, |
| 321 | unsigned long old_len, unsigned long new_addr, |
| 322 | unsigned long new_len) |
| 323 | { |
| 324 | struct mm_struct *mm = current->mm; |
| 325 | struct vm_area_struct *vma; |
| 326 | unsigned long ret = -EINVAL; |
| 327 | unsigned long charged = 0; |
Al Viro | 097eed1 | 2009-11-24 08:43:52 -0500 | [diff] [blame^] | 328 | unsigned long map_flags; |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 329 | |
| 330 | if (new_addr & ~PAGE_MASK) |
| 331 | goto out; |
| 332 | |
| 333 | if (new_len > TASK_SIZE || new_addr > TASK_SIZE - new_len) |
| 334 | goto out; |
| 335 | |
| 336 | /* Check if the location we're moving into overlaps the |
| 337 | * old location at all, and fail if it does. |
| 338 | */ |
| 339 | if ((new_addr <= addr) && (new_addr+new_len) > addr) |
| 340 | goto out; |
| 341 | |
| 342 | if ((addr <= new_addr) && (addr+old_len) > new_addr) |
| 343 | goto out; |
| 344 | |
| 345 | ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); |
| 346 | if (ret) |
| 347 | goto out; |
| 348 | |
| 349 | ret = do_munmap(mm, new_addr, new_len); |
| 350 | if (ret) |
| 351 | goto out; |
| 352 | |
| 353 | if (old_len >= new_len) { |
| 354 | ret = do_munmap(mm, addr+new_len, old_len - new_len); |
| 355 | if (ret && old_len != new_len) |
| 356 | goto out; |
| 357 | old_len = new_len; |
| 358 | } |
| 359 | |
| 360 | vma = vma_to_resize(addr, old_len, new_len, &charged); |
| 361 | if (IS_ERR(vma)) { |
| 362 | ret = PTR_ERR(vma); |
| 363 | goto out; |
| 364 | } |
| 365 | |
Al Viro | 097eed1 | 2009-11-24 08:43:52 -0500 | [diff] [blame^] | 366 | map_flags = MAP_FIXED; |
| 367 | if (vma->vm_flags & VM_MAYSHARE) |
| 368 | map_flags |= MAP_SHARED; |
| 369 | ret = arch_mmap_check(new_addr, new_len, map_flags); |
| 370 | if (ret) |
| 371 | goto out1; |
| 372 | ret = get_unmapped_area(vma->vm_file, new_addr, new_len, vma->vm_pgoff + |
| 373 | ((addr - vma->vm_start) >> PAGE_SHIFT), |
| 374 | map_flags); |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 375 | if (ret & ~PAGE_MASK) |
Al Viro | 097eed1 | 2009-11-24 08:43:52 -0500 | [diff] [blame^] | 376 | goto out1; |
| 377 | |
| 378 | ret = move_vma(vma, addr, old_len, new_len, new_addr); |
| 379 | if (!(ret & ~PAGE_MASK)) |
| 380 | goto out; |
| 381 | out1: |
| 382 | vm_unacct_memory(charged); |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 383 | |
| 384 | out: |
| 385 | return ret; |
| 386 | } |
| 387 | |
Al Viro | 1a0ef85 | 2009-11-24 07:43:18 -0500 | [diff] [blame] | 388 | static int vma_expandable(struct vm_area_struct *vma, unsigned long delta) |
| 389 | { |
Al Viro | f106af4 | 2009-11-24 08:25:18 -0500 | [diff] [blame] | 390 | unsigned long end = vma->vm_end + delta; |
Al Viro | 1a0ef85 | 2009-11-24 07:43:18 -0500 | [diff] [blame] | 391 | unsigned long max_addr = TASK_SIZE; |
| 392 | if (vma->vm_next) |
| 393 | max_addr = vma->vm_next->vm_start; |
Al Viro | f106af4 | 2009-11-24 08:25:18 -0500 | [diff] [blame] | 394 | if (max_addr < end || end < vma->vm_end) |
Al Viro | 1a0ef85 | 2009-11-24 07:43:18 -0500 | [diff] [blame] | 395 | return 0; |
Al Viro | f106af4 | 2009-11-24 08:25:18 -0500 | [diff] [blame] | 396 | if (arch_mmap_check(vma->vm_start, end - vma->vm_start, MAP_FIXED)) |
| 397 | return 0; |
| 398 | if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start, |
| 399 | 0, MAP_FIXED) & ~PAGE_MASK) |
| 400 | return 0; |
Al Viro | 1a0ef85 | 2009-11-24 07:43:18 -0500 | [diff] [blame] | 401 | return 1; |
| 402 | } |
| 403 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 404 | /* |
| 405 | * Expand (or shrink) an existing mapping, potentially moving it at the |
| 406 | * same time (controlled by the MREMAP_MAYMOVE flag and available VM space) |
| 407 | * |
| 408 | * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise |
| 409 | * This option implies MREMAP_MAYMOVE. |
| 410 | */ |
| 411 | unsigned long do_mremap(unsigned long addr, |
| 412 | unsigned long old_len, unsigned long new_len, |
| 413 | unsigned long flags, unsigned long new_addr) |
| 414 | { |
Hugh Dickins | d0de32d | 2005-10-29 18:16:16 -0700 | [diff] [blame] | 415 | struct mm_struct *mm = current->mm; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 416 | struct vm_area_struct *vma; |
| 417 | unsigned long ret = -EINVAL; |
| 418 | unsigned long charged = 0; |
| 419 | |
| 420 | if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) |
| 421 | goto out; |
| 422 | |
| 423 | if (addr & ~PAGE_MASK) |
| 424 | goto out; |
| 425 | |
| 426 | old_len = PAGE_ALIGN(old_len); |
| 427 | new_len = PAGE_ALIGN(new_len); |
| 428 | |
| 429 | /* |
| 430 | * We allow a zero old-len as a special case |
| 431 | * for DOS-emu "duplicate shm area" thing. But |
| 432 | * a zero new-len is nonsensical. |
| 433 | */ |
| 434 | if (!new_len) |
| 435 | goto out; |
| 436 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 437 | if (flags & MREMAP_FIXED) { |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 438 | if (flags & MREMAP_MAYMOVE) |
| 439 | ret = mremap_to(addr, old_len, new_addr, new_len); |
| 440 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 441 | } |
| 442 | |
| 443 | /* |
| 444 | * Always allow a shrinking remap: that just unmaps |
| 445 | * the unnecessary pages.. |
| 446 | * do_munmap does all the needed commit accounting |
| 447 | */ |
| 448 | if (old_len >= new_len) { |
Hugh Dickins | d0de32d | 2005-10-29 18:16:16 -0700 | [diff] [blame] | 449 | ret = do_munmap(mm, addr+new_len, old_len - new_len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 450 | if (ret && old_len != new_len) |
| 451 | goto out; |
| 452 | ret = addr; |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 453 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 454 | } |
| 455 | |
| 456 | /* |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 457 | * Ok, we need to grow.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 458 | */ |
Al Viro | 54f5de7 | 2009-11-24 07:17:46 -0500 | [diff] [blame] | 459 | vma = vma_to_resize(addr, old_len, new_len, &charged); |
| 460 | if (IS_ERR(vma)) { |
| 461 | ret = PTR_ERR(vma); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 462 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 463 | } |
| 464 | |
| 465 | /* old_len exactly to the end of the area.. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 466 | */ |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 467 | if (old_len == vma->vm_end - addr) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 468 | /* can we just expand the current mapping? */ |
Al Viro | 1a0ef85 | 2009-11-24 07:43:18 -0500 | [diff] [blame] | 469 | if (vma_expandable(vma, new_len - old_len)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 470 | int pages = (new_len - old_len) >> PAGE_SHIFT; |
| 471 | |
| 472 | vma_adjust(vma, vma->vm_start, |
| 473 | addr + new_len, vma->vm_pgoff, NULL); |
| 474 | |
Hugh Dickins | d0de32d | 2005-10-29 18:16:16 -0700 | [diff] [blame] | 475 | mm->total_vm += pages; |
| 476 | vm_stat_account(mm, vma->vm_flags, vma->vm_file, pages); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 477 | if (vma->vm_flags & VM_LOCKED) { |
Hugh Dickins | d0de32d | 2005-10-29 18:16:16 -0700 | [diff] [blame] | 478 | mm->locked_vm += pages; |
Rik van Riel | ba470de | 2008-10-18 20:26:50 -0700 | [diff] [blame] | 479 | mlock_vma_pages_range(vma, addr + old_len, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 480 | addr + new_len); |
| 481 | } |
| 482 | ret = addr; |
| 483 | goto out; |
| 484 | } |
| 485 | } |
| 486 | |
| 487 | /* |
| 488 | * We weren't able to just expand or shrink the area, |
| 489 | * we need to create a new one and move it.. |
| 490 | */ |
| 491 | ret = -ENOMEM; |
| 492 | if (flags & MREMAP_MAYMOVE) { |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 493 | unsigned long map_flags = 0; |
| 494 | if (vma->vm_flags & VM_MAYSHARE) |
| 495 | map_flags |= MAP_SHARED; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 496 | |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 497 | new_addr = get_unmapped_area(vma->vm_file, 0, new_len, |
| 498 | vma->vm_pgoff, map_flags); |
| 499 | if (new_addr & ~PAGE_MASK) { |
| 500 | ret = new_addr; |
| 501 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 502 | } |
Al Viro | ecc1a89 | 2009-11-24 07:28:07 -0500 | [diff] [blame] | 503 | |
| 504 | ret = security_file_mmap(NULL, 0, 0, 0, new_addr, 1); |
| 505 | if (ret) |
| 506 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | ret = move_vma(vma, addr, old_len, new_len, new_addr); |
| 508 | } |
| 509 | out: |
| 510 | if (ret & ~PAGE_MASK) |
| 511 | vm_unacct_memory(charged); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 512 | return ret; |
| 513 | } |
| 514 | |
Heiko Carstens | 6a6160a | 2009-01-14 14:14:15 +0100 | [diff] [blame] | 515 | SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, |
| 516 | unsigned long, new_len, unsigned long, flags, |
| 517 | unsigned long, new_addr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 518 | { |
| 519 | unsigned long ret; |
| 520 | |
| 521 | down_write(¤t->mm->mmap_sem); |
| 522 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); |
| 523 | up_write(¤t->mm->mmap_sem); |
| 524 | return ret; |
| 525 | } |