4 * Replacement code for mm functions to support CPU's that don't
5 * have any form of memory management unit (thus no virtual memory).
7 * See Documentation/nommu-mmap.txt
9 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
13 * Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
16 #include <linux/module.h>
18 #include <linux/mman.h>
19 #include <linux/swap.h>
20 #include <linux/file.h>
21 #include <linux/highmem.h>
22 #include <linux/pagemap.h>
23 #include <linux/slab.h>
24 #include <linux/vmalloc.h>
25 #include <linux/tracehook.h>
26 #include <linux/blkdev.h>
27 #include <linux/backing-dev.h>
28 #include <linux/mount.h>
29 #include <linux/personality.h>
30 #include <linux/security.h>
31 #include <linux/syscalls.h>
33 #include <asm/uaccess.h>
35 #include <asm/tlbflush.h>
38 static inline __attribute__((format(printf, 1, 2)))
39 void no_printk(const char *fmt, ...)
44 #define kenter(FMT, ...) \
45 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
46 #define kleave(FMT, ...) \
47 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
48 #define kdebug(FMT, ...) \
49 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
51 #define kenter(FMT, ...) \
52 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
53 #define kleave(FMT, ...) \
54 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
55 #define kdebug(FMT, ...) \
56 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
63 unsigned long max_mapnr;
64 unsigned long num_physpages;
65 struct percpu_counter vm_committed_as;
66 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
67 int sysctl_overcommit_ratio = 50; /* default is 50% */
68 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
69 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
70 int heap_stack_gap = 0;
72 atomic_long_t mmap_pages_allocated;
74 EXPORT_SYMBOL(mem_map);
75 EXPORT_SYMBOL(num_physpages);
77 /* list of mapped, potentially shareable regions */
78 static struct kmem_cache *vm_region_jar;
79 struct rb_root nommu_region_tree = RB_ROOT;
80 DECLARE_RWSEM(nommu_region_sem);
82 struct vm_operations_struct generic_file_vm_ops = {
86 * Handle all mappings that got truncated by a "truncate()"
89 * NOTE! We have to be ready to update the memory sharing
90 * between the file and the memory map for a potential last
91 * incomplete page. Ugly, but necessary.
93 int vmtruncate(struct inode *inode, loff_t offset)
95 struct address_space *mapping = inode->i_mapping;
98 if (inode->i_size < offset)
100 i_size_write(inode, offset);
102 truncate_inode_pages(mapping, offset);
106 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
107 if (limit != RLIM_INFINITY && offset > limit)
109 if (offset > inode->i_sb->s_maxbytes)
111 i_size_write(inode, offset);
114 if (inode->i_op->truncate)
115 inode->i_op->truncate(inode);
118 send_sig(SIGXFSZ, current, 0);
123 EXPORT_SYMBOL(vmtruncate);
126 * Return the total memory allocated for this pointer, not
127 * just what the caller asked for.
129 * Doesn't have to be accurate, i.e. may have races.
131 unsigned int kobjsize(const void *objp)
136 * If the object we have should not have ksize performed on it,
139 if (!objp || !virt_addr_valid(objp))
142 page = virt_to_head_page(objp);
145 * If the allocator sets PageSlab, we know the pointer came from
152 * If it's not a compound page, see if we have a matching VMA
153 * region. This test is intentionally done in reverse order,
154 * so if there's no VMA, we still fall through and hand back
155 * PAGE_SIZE for 0-order pages.
157 if (!PageCompound(page)) {
158 struct vm_area_struct *vma;
160 vma = find_vma(current->mm, (unsigned long)objp);
162 return vma->vm_end - vma->vm_start;
166 * The ksize() function is only guaranteed to work for pointers
167 * returned by kmalloc(). So handle arbitrary pointers here.
169 return PAGE_SIZE << compound_order(page);
172 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
173 unsigned long start, int nr_pages, int flags,
174 struct page **pages, struct vm_area_struct **vmas)
176 struct vm_area_struct *vma;
177 unsigned long vm_flags;
179 int write = !!(flags & GUP_FLAGS_WRITE);
180 int force = !!(flags & GUP_FLAGS_FORCE);
181 int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
183 /* calculate required read or write permissions.
184 * - if 'force' is set, we only require the "MAY" flags.
186 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
187 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
189 for (i = 0; i < nr_pages; i++) {
190 vma = find_vma(mm, start);
192 goto finish_or_fault;
194 /* protect what we can, including chardevs */
195 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
196 (!ignore && !(vm_flags & vma->vm_flags)))
197 goto finish_or_fault;
200 pages[i] = virt_to_page(start);
202 page_cache_get(pages[i]);
212 return i ? : -EFAULT;
217 * get a list of pages in an address range belonging to the specified process
218 * and indicate the VMA that covers each page
219 * - this is potentially dodgy as we may end incrementing the page count of a
220 * slab page or a secondary page from a compound page
221 * - don't permit access to VMAs that don't support it, such as I/O mappings
223 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
224 unsigned long start, int nr_pages, int write, int force,
225 struct page **pages, struct vm_area_struct **vmas)
230 flags |= GUP_FLAGS_WRITE;
232 flags |= GUP_FLAGS_FORCE;
234 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
236 EXPORT_SYMBOL(get_user_pages);
239 * follow_pfn - look up PFN at a user virtual address
240 * @vma: memory mapping
241 * @address: user virtual address
242 * @pfn: location to store found PFN
244 * Only IO mappings and raw PFN mappings are allowed.
246 * Returns zero and the pfn at @pfn on success, -ve otherwise.
248 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
251 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
254 *pfn = address >> PAGE_SHIFT;
257 EXPORT_SYMBOL(follow_pfn);
259 DEFINE_RWLOCK(vmlist_lock);
260 struct vm_struct *vmlist;
262 void vfree(const void *addr)
266 EXPORT_SYMBOL(vfree);
268 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
271 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
272 * returns only a logical address.
274 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
276 EXPORT_SYMBOL(__vmalloc);
278 void *vmalloc_user(unsigned long size)
282 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
285 struct vm_area_struct *vma;
287 down_write(¤t->mm->mmap_sem);
288 vma = find_vma(current->mm, (unsigned long)ret);
290 vma->vm_flags |= VM_USERMAP;
291 up_write(¤t->mm->mmap_sem);
296 EXPORT_SYMBOL(vmalloc_user);
298 struct page *vmalloc_to_page(const void *addr)
300 return virt_to_page(addr);
302 EXPORT_SYMBOL(vmalloc_to_page);
304 unsigned long vmalloc_to_pfn(const void *addr)
306 return page_to_pfn(virt_to_page(addr));
308 EXPORT_SYMBOL(vmalloc_to_pfn);
310 long vread(char *buf, char *addr, unsigned long count)
312 memcpy(buf, addr, count);
316 long vwrite(char *buf, char *addr, unsigned long count)
318 /* Don't allow overflow */
319 if ((unsigned long) addr + count < count)
320 count = -(unsigned long) addr;
322 memcpy(addr, buf, count);
327 * vmalloc - allocate virtually continguos memory
329 * @size: allocation size
331 * Allocate enough pages to cover @size from the page level
332 * allocator and map them into continguos kernel virtual space.
334 * For tight control over page level allocator and protection flags
335 * use __vmalloc() instead.
337 void *vmalloc(unsigned long size)
339 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
341 EXPORT_SYMBOL(vmalloc);
343 void *vmalloc_node(unsigned long size, int node)
345 return vmalloc(size);
347 EXPORT_SYMBOL(vmalloc_node);
349 #ifndef PAGE_KERNEL_EXEC
350 # define PAGE_KERNEL_EXEC PAGE_KERNEL
354 * vmalloc_exec - allocate virtually contiguous, executable memory
355 * @size: allocation size
357 * Kernel-internal function to allocate enough pages to cover @size
358 * the page level allocator and map them into contiguous and
359 * executable kernel virtual space.
361 * For tight control over page level allocator and protection flags
362 * use __vmalloc() instead.
365 void *vmalloc_exec(unsigned long size)
367 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
371 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
372 * @size: allocation size
374 * Allocate enough 32bit PA addressable pages to cover @size from the
375 * page level allocator and map them into continguos kernel virtual space.
377 void *vmalloc_32(unsigned long size)
379 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
381 EXPORT_SYMBOL(vmalloc_32);
384 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
385 * @size: allocation size
387 * The resulting memory area is 32bit addressable and zeroed so it can be
388 * mapped to userspace without leaking data.
390 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
391 * remap_vmalloc_range() are permissible.
393 void *vmalloc_32_user(unsigned long size)
396 * We'll have to sort out the ZONE_DMA bits for 64-bit,
397 * but for now this can simply use vmalloc_user() directly.
399 return vmalloc_user(size);
401 EXPORT_SYMBOL(vmalloc_32_user);
403 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
410 void vunmap(const void *addr)
414 EXPORT_SYMBOL(vunmap);
416 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
421 EXPORT_SYMBOL(vm_map_ram);
423 void vm_unmap_ram(const void *mem, unsigned int count)
427 EXPORT_SYMBOL(vm_unmap_ram);
429 void vm_unmap_aliases(void)
432 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
435 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
438 void __attribute__((weak)) vmalloc_sync_all(void)
442 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
447 EXPORT_SYMBOL(vm_insert_page);
450 * sys_brk() for the most part doesn't need the global kernel
451 * lock, except when an application is doing something nasty
452 * like trying to un-brk an area that has already been mapped
453 * to a regular file. in this case, the unmapping will need
454 * to invoke file system routines that need the global lock.
456 SYSCALL_DEFINE1(brk, unsigned long, brk)
458 struct mm_struct *mm = current->mm;
460 if (brk < mm->start_brk || brk > mm->context.end_brk)
467 * Always allow shrinking brk
469 if (brk <= mm->brk) {
475 * Ok, looks good - let it rip.
477 return mm->brk = brk;
481 * initialise the VMA and region record slabs
483 void __init mmap_init(void)
487 ret = percpu_counter_init(&vm_committed_as, 0);
489 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
493 * validate the region tree
494 * - the caller must hold the region lock
496 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
497 static noinline void validate_nommu_regions(void)
499 struct vm_region *region, *last;
500 struct rb_node *p, *lastp;
502 lastp = rb_first(&nommu_region_tree);
506 last = rb_entry(lastp, struct vm_region, vm_rb);
507 BUG_ON(unlikely(last->vm_end <= last->vm_start));
508 BUG_ON(unlikely(last->vm_top < last->vm_end));
510 while ((p = rb_next(lastp))) {
511 region = rb_entry(p, struct vm_region, vm_rb);
512 last = rb_entry(lastp, struct vm_region, vm_rb);
514 BUG_ON(unlikely(region->vm_end <= region->vm_start));
515 BUG_ON(unlikely(region->vm_top < region->vm_end));
516 BUG_ON(unlikely(region->vm_start < last->vm_top));
522 static void validate_nommu_regions(void)
528 * add a region into the global tree
530 static void add_nommu_region(struct vm_region *region)
532 struct vm_region *pregion;
533 struct rb_node **p, *parent;
535 validate_nommu_regions();
538 p = &nommu_region_tree.rb_node;
541 pregion = rb_entry(parent, struct vm_region, vm_rb);
542 if (region->vm_start < pregion->vm_start)
544 else if (region->vm_start > pregion->vm_start)
546 else if (pregion == region)
552 rb_link_node(®ion->vm_rb, parent, p);
553 rb_insert_color(®ion->vm_rb, &nommu_region_tree);
555 validate_nommu_regions();
559 * delete a region from the global tree
561 static void delete_nommu_region(struct vm_region *region)
563 BUG_ON(!nommu_region_tree.rb_node);
565 validate_nommu_regions();
566 rb_erase(®ion->vm_rb, &nommu_region_tree);
567 validate_nommu_regions();
571 * free a contiguous series of pages
573 static void free_page_series(unsigned long from, unsigned long to)
575 for (; from < to; from += PAGE_SIZE) {
576 struct page *page = virt_to_page(from);
578 kdebug("- free %lx", from);
579 atomic_long_dec(&mmap_pages_allocated);
580 if (page_count(page) != 1)
581 kdebug("free page %p: refcount not one: %d",
582 page, page_count(page));
588 * release a reference to a region
589 * - the caller must hold the region semaphore for writing, which this releases
590 * - the region may not have been added to the tree yet, in which case vm_top
591 * will equal vm_start
593 static void __put_nommu_region(struct vm_region *region)
594 __releases(nommu_region_sem)
596 kenter("%p{%d}", region, atomic_read(®ion->vm_usage));
598 BUG_ON(!nommu_region_tree.rb_node);
600 if (atomic_dec_and_test(®ion->vm_usage)) {
601 if (region->vm_top > region->vm_start)
602 delete_nommu_region(region);
603 up_write(&nommu_region_sem);
606 fput(region->vm_file);
608 /* IO memory and memory shared directly out of the pagecache
609 * from ramfs/tmpfs mustn't be released here */
610 if (region->vm_flags & VM_MAPPED_COPY) {
611 kdebug("free series");
612 free_page_series(region->vm_start, region->vm_top);
614 kmem_cache_free(vm_region_jar, region);
616 up_write(&nommu_region_sem);
621 * release a reference to a region
623 static void put_nommu_region(struct vm_region *region)
625 down_write(&nommu_region_sem);
626 __put_nommu_region(region);
630 * add a VMA into a process's mm_struct in the appropriate place in the list
631 * and tree and add to the address space's page tree also if not an anonymous
633 * - should be called with mm->mmap_sem held writelocked
635 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
637 struct vm_area_struct *pvma, **pp;
638 struct address_space *mapping;
639 struct rb_node **p, *parent;
643 BUG_ON(!vma->vm_region);
648 /* add the VMA to the mapping */
650 mapping = vma->vm_file->f_mapping;
652 flush_dcache_mmap_lock(mapping);
653 vma_prio_tree_insert(vma, &mapping->i_mmap);
654 flush_dcache_mmap_unlock(mapping);
657 /* add the VMA to the tree */
659 p = &mm->mm_rb.rb_node;
662 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
664 /* sort by: start addr, end addr, VMA struct addr in that order
665 * (the latter is necessary as we may get identical VMAs) */
666 if (vma->vm_start < pvma->vm_start)
668 else if (vma->vm_start > pvma->vm_start)
670 else if (vma->vm_end < pvma->vm_end)
672 else if (vma->vm_end > pvma->vm_end)
682 rb_link_node(&vma->vm_rb, parent, p);
683 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
685 /* add VMA to the VMA list also */
686 for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
687 if (pvma->vm_start > vma->vm_start)
689 if (pvma->vm_start < vma->vm_start)
691 if (pvma->vm_end < vma->vm_end)
700 * delete a VMA from its owning mm_struct and address space
702 static void delete_vma_from_mm(struct vm_area_struct *vma)
704 struct vm_area_struct **pp;
705 struct address_space *mapping;
706 struct mm_struct *mm = vma->vm_mm;
711 if (mm->mmap_cache == vma)
712 mm->mmap_cache = NULL;
714 /* remove the VMA from the mapping */
716 mapping = vma->vm_file->f_mapping;
718 flush_dcache_mmap_lock(mapping);
719 vma_prio_tree_remove(vma, &mapping->i_mmap);
720 flush_dcache_mmap_unlock(mapping);
723 /* remove from the MM's tree and list */
724 rb_erase(&vma->vm_rb, &mm->mm_rb);
725 for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
736 * destroy a VMA record
738 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
741 if (vma->vm_ops && vma->vm_ops->close)
742 vma->vm_ops->close(vma);
745 if (vma->vm_flags & VM_EXECUTABLE)
746 removed_exe_file_vma(mm);
748 put_nommu_region(vma->vm_region);
749 kmem_cache_free(vm_area_cachep, vma);
753 * look up the first VMA in which addr resides, NULL if none
754 * - should be called with mm->mmap_sem at least held readlocked
756 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
758 struct vm_area_struct *vma;
759 struct rb_node *n = mm->mm_rb.rb_node;
761 /* check the cache first */
762 vma = mm->mmap_cache;
763 if (vma && vma->vm_start <= addr && vma->vm_end > addr)
766 /* trawl the tree (there may be multiple mappings in which addr
768 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
769 vma = rb_entry(n, struct vm_area_struct, vm_rb);
770 if (vma->vm_start > addr)
772 if (vma->vm_end > addr) {
773 mm->mmap_cache = vma;
780 EXPORT_SYMBOL(find_vma);
784 * - we don't extend stack VMAs under NOMMU conditions
786 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
788 return find_vma(mm, addr);
792 * expand a stack to a given address
793 * - not supported under NOMMU conditions
795 int expand_stack(struct vm_area_struct *vma, unsigned long address)
801 * look up the first VMA exactly that exactly matches addr
802 * - should be called with mm->mmap_sem at least held readlocked
804 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
808 struct vm_area_struct *vma;
809 struct rb_node *n = mm->mm_rb.rb_node;
810 unsigned long end = addr + len;
812 /* check the cache first */
813 vma = mm->mmap_cache;
814 if (vma && vma->vm_start == addr && vma->vm_end == end)
817 /* trawl the tree (there may be multiple mappings in which addr
819 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
820 vma = rb_entry(n, struct vm_area_struct, vm_rb);
821 if (vma->vm_start < addr)
823 if (vma->vm_start > addr)
825 if (vma->vm_end == end) {
826 mm->mmap_cache = vma;
835 * determine whether a mapping should be permitted and, if so, what sort of
836 * mapping we're capable of supporting
838 static int validate_mmap_request(struct file *file,
844 unsigned long *_capabilities)
846 unsigned long capabilities, rlen;
847 unsigned long reqprot = prot;
850 /* do the simple checks first */
851 if (flags & MAP_FIXED || addr) {
853 "%d: Can't do fixed-address/overlay mmap of RAM\n",
858 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
859 (flags & MAP_TYPE) != MAP_SHARED)
865 /* Careful about overflows.. */
866 rlen = PAGE_ALIGN(len);
867 if (!rlen || rlen > TASK_SIZE)
870 /* offset overflow? */
871 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
875 /* validate file mapping requests */
876 struct address_space *mapping;
878 /* files must support mmap */
879 if (!file->f_op || !file->f_op->mmap)
882 /* work out if what we've got could possibly be shared
883 * - we support chardevs that provide their own "memory"
884 * - we support files/blockdevs that are memory backed
886 mapping = file->f_mapping;
888 mapping = file->f_path.dentry->d_inode->i_mapping;
891 if (mapping && mapping->backing_dev_info)
892 capabilities = mapping->backing_dev_info->capabilities;
895 /* no explicit capabilities set, so assume some
897 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
900 capabilities = BDI_CAP_MAP_COPY;
915 /* eliminate any capabilities that we can't support on this
917 if (!file->f_op->get_unmapped_area)
918 capabilities &= ~BDI_CAP_MAP_DIRECT;
919 if (!file->f_op->read)
920 capabilities &= ~BDI_CAP_MAP_COPY;
922 /* The file shall have been opened with read permission. */
923 if (!(file->f_mode & FMODE_READ))
926 if (flags & MAP_SHARED) {
927 /* do checks for writing, appending and locking */
928 if ((prot & PROT_WRITE) &&
929 !(file->f_mode & FMODE_WRITE))
932 if (IS_APPEND(file->f_path.dentry->d_inode) &&
933 (file->f_mode & FMODE_WRITE))
936 if (locks_verify_locked(file->f_path.dentry->d_inode))
939 if (!(capabilities & BDI_CAP_MAP_DIRECT))
942 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
943 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
944 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
946 printk("MAP_SHARED not completely supported on !MMU\n");
950 /* we mustn't privatise shared mappings */
951 capabilities &= ~BDI_CAP_MAP_COPY;
954 /* we're going to read the file into private memory we
956 if (!(capabilities & BDI_CAP_MAP_COPY))
959 /* we don't permit a private writable mapping to be
960 * shared with the backing device */
961 if (prot & PROT_WRITE)
962 capabilities &= ~BDI_CAP_MAP_DIRECT;
965 /* handle executable mappings and implied executable
967 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
968 if (prot & PROT_EXEC)
971 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
972 /* handle implication of PROT_EXEC by PROT_READ */
973 if (current->personality & READ_IMPLIES_EXEC) {
974 if (capabilities & BDI_CAP_EXEC_MAP)
978 else if ((prot & PROT_READ) &&
979 (prot & PROT_EXEC) &&
980 !(capabilities & BDI_CAP_EXEC_MAP)
982 /* backing file is not executable, try to copy */
983 capabilities &= ~BDI_CAP_MAP_DIRECT;
987 /* anonymous mappings are always memory backed and can be
990 capabilities = BDI_CAP_MAP_COPY;
992 /* handle PROT_EXEC implication by PROT_READ */
993 if ((prot & PROT_READ) &&
994 (current->personality & READ_IMPLIES_EXEC))
998 /* allow the security API to have its say */
999 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1004 *_capabilities = capabilities;
1009 * we've determined that we can make the mapping, now translate what we
1010 * now know into VMA flags
1012 static unsigned long determine_vm_flags(struct file *file,
1014 unsigned long flags,
1015 unsigned long capabilities)
1017 unsigned long vm_flags;
1019 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1020 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1021 /* vm_flags |= mm->def_flags; */
1023 if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1024 /* attempt to share read-only copies of mapped file chunks */
1025 if (file && !(prot & PROT_WRITE))
1026 vm_flags |= VM_MAYSHARE;
1029 /* overlay a shareable mapping on the backing device or inode
1030 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1032 if (flags & MAP_SHARED)
1033 vm_flags |= VM_MAYSHARE | VM_SHARED;
1034 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
1035 vm_flags |= VM_MAYSHARE;
1038 /* refuse to let anyone share private mappings with this process if
1039 * it's being traced - otherwise breakpoints set in it may interfere
1040 * with another untraced process
1042 if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
1043 vm_flags &= ~VM_MAYSHARE;
1049 * set up a shared mapping on a file (the driver or filesystem provides and
1052 static int do_mmap_shared_file(struct vm_area_struct *vma)
1056 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1058 vma->vm_region->vm_top = vma->vm_region->vm_end;
1064 /* getting an ENOSYS error indicates that direct mmap isn't
1065 * possible (as opposed to tried but failed) so we'll fall
1066 * through to making a private copy of the data and mapping
1072 * set up a private mapping or an anonymous shared mapping
1074 static int do_mmap_private(struct vm_area_struct *vma,
1075 struct vm_region *region,
1079 unsigned long total, point, n, rlen;
1083 /* invoke the file's mapping function so that it can keep track of
1084 * shared mappings on devices or memory
1085 * - VM_MAYSHARE will be set if it may attempt to share
1088 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1090 /* shouldn't return success if we're not sharing */
1091 BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1092 vma->vm_region->vm_top = vma->vm_region->vm_end;
1098 /* getting an ENOSYS error indicates that direct mmap isn't
1099 * possible (as opposed to tried but failed) so we'll try to
1100 * make a private copy of the data and map that instead */
1103 rlen = PAGE_ALIGN(len);
1105 /* allocate some memory to hold the mapping
1106 * - note that this may not return a page-aligned address if the object
1107 * we're allocating is smaller than a page
1109 order = get_order(rlen);
1110 kdebug("alloc order %d for %lx", order, len);
1112 pages = alloc_pages(GFP_KERNEL, order);
1117 atomic_long_add(total, &mmap_pages_allocated);
1119 point = rlen >> PAGE_SHIFT;
1121 /* we allocated a power-of-2 sized page set, so we may want to trim off
1123 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1124 while (total > point) {
1125 order = ilog2(total - point);
1127 kdebug("shave %lu/%lu @%lu", n, total - point, total);
1128 atomic_long_sub(n, &mmap_pages_allocated);
1130 set_page_refcounted(pages + total);
1131 __free_pages(pages + total, order);
1135 for (point = 1; point < total; point++)
1136 set_page_refcounted(&pages[point]);
1138 base = page_address(pages);
1139 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1140 region->vm_start = (unsigned long) base;
1141 region->vm_end = region->vm_start + rlen;
1142 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
1144 vma->vm_start = region->vm_start;
1145 vma->vm_end = region->vm_start + len;
1148 /* read the contents of a file into the copy */
1149 mm_segment_t old_fs;
1152 fpos = vma->vm_pgoff;
1153 fpos <<= PAGE_SHIFT;
1157 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
1163 /* clear the last little bit */
1165 memset(base + ret, 0, rlen - ret);
1168 /* if it's an anonymous mapping, then just clear it */
1169 memset(base, 0, rlen);
1175 free_page_series(region->vm_start, region->vm_end);
1176 region->vm_start = vma->vm_start = 0;
1177 region->vm_end = vma->vm_end = 0;
1182 printk("Allocation of length %lu from process %d (%s) failed\n",
1183 len, current->pid, current->comm);
1189 * handle mapping creation for uClinux
1191 unsigned long do_mmap_pgoff(struct file *file,
1195 unsigned long flags,
1196 unsigned long pgoff)
1198 struct vm_area_struct *vma;
1199 struct vm_region *region;
1201 unsigned long capabilities, vm_flags, result;
1204 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1206 if (!(flags & MAP_FIXED))
1207 addr = round_hint_to_min(addr);
1209 /* decide whether we should attempt the mapping, and if so what sort of
1211 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1214 kleave(" = %d [val]", ret);
1218 /* we've determined that we can make the mapping, now translate what we
1219 * now know into VMA flags */
1220 vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1222 /* we're going to need to record the mapping */
1223 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1225 goto error_getting_region;
1227 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1229 goto error_getting_vma;
1231 atomic_set(®ion->vm_usage, 1);
1232 region->vm_flags = vm_flags;
1233 region->vm_pgoff = pgoff;
1235 INIT_LIST_HEAD(&vma->anon_vma_node);
1236 vma->vm_flags = vm_flags;
1237 vma->vm_pgoff = pgoff;
1240 region->vm_file = file;
1242 vma->vm_file = file;
1244 if (vm_flags & VM_EXECUTABLE) {
1245 added_exe_file_vma(current->mm);
1246 vma->vm_mm = current->mm;
1250 down_write(&nommu_region_sem);
1252 /* if we want to share, we need to check for regions created by other
1253 * mmap() calls that overlap with our proposed mapping
1254 * - we can only share with a superset match on most regular files
1255 * - shared mappings on character devices and memory backed files are
1256 * permitted to overlap inexactly as far as we are concerned for in
1257 * these cases, sharing is handled in the driver or filesystem rather
1260 if (vm_flags & VM_MAYSHARE) {
1261 struct vm_region *pregion;
1262 unsigned long pglen, rpglen, pgend, rpgend, start;
1264 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1265 pgend = pgoff + pglen;
1267 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1268 pregion = rb_entry(rb, struct vm_region, vm_rb);
1270 if (!(pregion->vm_flags & VM_MAYSHARE))
1273 /* search for overlapping mappings on the same file */
1274 if (pregion->vm_file->f_path.dentry->d_inode !=
1275 file->f_path.dentry->d_inode)
1278 if (pregion->vm_pgoff >= pgend)
1281 rpglen = pregion->vm_end - pregion->vm_start;
1282 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1283 rpgend = pregion->vm_pgoff + rpglen;
1284 if (pgoff >= rpgend)
1287 /* handle inexactly overlapping matches between
1289 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1290 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1291 /* new mapping is not a subset of the region */
1292 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1293 goto sharing_violation;
1297 /* we've found a region we can share */
1298 atomic_inc(&pregion->vm_usage);
1299 vma->vm_region = pregion;
1300 start = pregion->vm_start;
1301 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1302 vma->vm_start = start;
1303 vma->vm_end = start + len;
1305 if (pregion->vm_flags & VM_MAPPED_COPY) {
1306 kdebug("share copy");
1307 vma->vm_flags |= VM_MAPPED_COPY;
1309 kdebug("share mmap");
1310 ret = do_mmap_shared_file(vma);
1312 vma->vm_region = NULL;
1315 atomic_dec(&pregion->vm_usage);
1317 goto error_just_free;
1320 fput(region->vm_file);
1321 kmem_cache_free(vm_region_jar, region);
1327 /* obtain the address at which to make a shared mapping
1328 * - this is the hook for quasi-memory character devices to
1329 * tell us the location of a shared mapping
1331 if (file && file->f_op->get_unmapped_area) {
1332 addr = file->f_op->get_unmapped_area(file, addr, len,
1334 if (IS_ERR((void *) addr)) {
1336 if (ret != (unsigned long) -ENOSYS)
1337 goto error_just_free;
1339 /* the driver refused to tell us where to site
1340 * the mapping so we'll have to attempt to copy
1342 ret = (unsigned long) -ENODEV;
1343 if (!(capabilities & BDI_CAP_MAP_COPY))
1344 goto error_just_free;
1346 capabilities &= ~BDI_CAP_MAP_DIRECT;
1348 vma->vm_start = region->vm_start = addr;
1349 vma->vm_end = region->vm_end = addr + len;
1354 vma->vm_region = region;
1356 /* set up the mapping */
1357 if (file && vma->vm_flags & VM_SHARED)
1358 ret = do_mmap_shared_file(vma);
1360 ret = do_mmap_private(vma, region, len);
1362 goto error_put_region;
1364 add_nommu_region(region);
1366 /* okay... we have a mapping; now we have to register it */
1367 result = vma->vm_start;
1369 current->mm->total_vm += len >> PAGE_SHIFT;
1372 add_vma_to_mm(current->mm, vma);
1374 up_write(&nommu_region_sem);
1376 if (prot & PROT_EXEC)
1377 flush_icache_range(result, result + len);
1379 kleave(" = %lx", result);
1383 __put_nommu_region(region);
1387 if (vma->vm_flags & VM_EXECUTABLE)
1388 removed_exe_file_vma(vma->vm_mm);
1390 kmem_cache_free(vm_area_cachep, vma);
1392 kleave(" = %d [pr]", ret);
1396 up_write(&nommu_region_sem);
1398 fput(region->vm_file);
1399 kmem_cache_free(vm_region_jar, region);
1401 if (vma->vm_flags & VM_EXECUTABLE)
1402 removed_exe_file_vma(vma->vm_mm);
1403 kmem_cache_free(vm_area_cachep, vma);
1404 kleave(" = %d", ret);
1408 up_write(&nommu_region_sem);
1409 printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1414 kmem_cache_free(vm_region_jar, region);
1415 printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1416 " from process %d failed\n",
1421 error_getting_region:
1422 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1423 " from process %d failed\n",
1428 EXPORT_SYMBOL(do_mmap_pgoff);
1431 * split a vma into two pieces at address 'addr', a new vma is allocated either
1432 * for the first part or the tail.
1434 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1435 unsigned long addr, int new_below)
1437 struct vm_area_struct *new;
1438 struct vm_region *region;
1439 unsigned long npages;
1443 /* we're only permitted to split anonymous regions that have a single
1446 atomic_read(&vma->vm_region->vm_usage) != 1)
1449 if (mm->map_count >= sysctl_max_map_count)
1452 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1456 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1458 kmem_cache_free(vm_region_jar, region);
1462 /* most fields are the same, copy all, and then fixup */
1464 *region = *vma->vm_region;
1465 new->vm_region = region;
1467 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1470 region->vm_top = region->vm_end = new->vm_end = addr;
1472 region->vm_start = new->vm_start = addr;
1473 region->vm_pgoff = new->vm_pgoff += npages;
1476 if (new->vm_ops && new->vm_ops->open)
1477 new->vm_ops->open(new);
1479 delete_vma_from_mm(vma);
1480 down_write(&nommu_region_sem);
1481 delete_nommu_region(vma->vm_region);
1483 vma->vm_region->vm_start = vma->vm_start = addr;
1484 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1486 vma->vm_region->vm_end = vma->vm_end = addr;
1487 vma->vm_region->vm_top = addr;
1489 add_nommu_region(vma->vm_region);
1490 add_nommu_region(new->vm_region);
1491 up_write(&nommu_region_sem);
1492 add_vma_to_mm(mm, vma);
1493 add_vma_to_mm(mm, new);
1498 * shrink a VMA by removing the specified chunk from either the beginning or
1501 static int shrink_vma(struct mm_struct *mm,
1502 struct vm_area_struct *vma,
1503 unsigned long from, unsigned long to)
1505 struct vm_region *region;
1509 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1511 delete_vma_from_mm(vma);
1512 if (from > vma->vm_start)
1516 add_vma_to_mm(mm, vma);
1518 /* cut the backing region down to size */
1519 region = vma->vm_region;
1520 BUG_ON(atomic_read(®ion->vm_usage) != 1);
1522 down_write(&nommu_region_sem);
1523 delete_nommu_region(region);
1524 if (from > region->vm_start) {
1525 to = region->vm_top;
1526 region->vm_top = region->vm_end = from;
1528 region->vm_start = to;
1530 add_nommu_region(region);
1531 up_write(&nommu_region_sem);
1533 free_page_series(from, to);
1539 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1540 * VMA, though it need not cover the whole VMA
1542 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1544 struct vm_area_struct *vma;
1546 unsigned long end = start + len;
1549 kenter(",%lx,%zx", start, len);
1554 /* find the first potentially overlapping VMA */
1555 vma = find_vma(mm, start);
1557 static int limit = 0;
1560 "munmap of memory not mmapped by process %d"
1561 " (%s): 0x%lx-0x%lx\n",
1562 current->pid, current->comm,
1563 start, start + len - 1);
1569 /* we're allowed to split an anonymous VMA but not a file-backed one */
1572 if (start > vma->vm_start) {
1573 kleave(" = -EINVAL [miss]");
1576 if (end == vma->vm_end)
1577 goto erase_whole_vma;
1578 rb = rb_next(&vma->vm_rb);
1579 vma = rb_entry(rb, struct vm_area_struct, vm_rb);
1581 kleave(" = -EINVAL [split file]");
1584 /* the chunk must be a subset of the VMA found */
1585 if (start == vma->vm_start && end == vma->vm_end)
1586 goto erase_whole_vma;
1587 if (start < vma->vm_start || end > vma->vm_end) {
1588 kleave(" = -EINVAL [superset]");
1591 if (start & ~PAGE_MASK) {
1592 kleave(" = -EINVAL [unaligned start]");
1595 if (end != vma->vm_end && end & ~PAGE_MASK) {
1596 kleave(" = -EINVAL [unaligned split]");
1599 if (start != vma->vm_start && end != vma->vm_end) {
1600 ret = split_vma(mm, vma, start, 1);
1602 kleave(" = %d [split]", ret);
1606 return shrink_vma(mm, vma, start, end);
1610 delete_vma_from_mm(vma);
1611 delete_vma(mm, vma);
1615 EXPORT_SYMBOL(do_munmap);
1617 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1620 struct mm_struct *mm = current->mm;
1622 down_write(&mm->mmap_sem);
1623 ret = do_munmap(mm, addr, len);
1624 up_write(&mm->mmap_sem);
1629 * release all the mappings made in a process's VM space
1631 void exit_mmap(struct mm_struct *mm)
1633 struct vm_area_struct *vma;
1642 while ((vma = mm->mmap)) {
1643 mm->mmap = vma->vm_next;
1644 delete_vma_from_mm(vma);
1645 delete_vma(mm, vma);
1651 unsigned long do_brk(unsigned long addr, unsigned long len)
1657 * expand (or shrink) an existing mapping, potentially moving it at the same
1658 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1660 * under NOMMU conditions, we only permit changing a mapping's size, and only
1661 * as long as it stays within the region allocated by do_mmap_private() and the
1662 * block is not shareable
1664 * MREMAP_FIXED is not supported under NOMMU conditions
1666 unsigned long do_mremap(unsigned long addr,
1667 unsigned long old_len, unsigned long new_len,
1668 unsigned long flags, unsigned long new_addr)
1670 struct vm_area_struct *vma;
1672 /* insanity checks first */
1673 if (old_len == 0 || new_len == 0)
1674 return (unsigned long) -EINVAL;
1676 if (addr & ~PAGE_MASK)
1679 if (flags & MREMAP_FIXED && new_addr != addr)
1680 return (unsigned long) -EINVAL;
1682 vma = find_vma_exact(current->mm, addr, old_len);
1684 return (unsigned long) -EINVAL;
1686 if (vma->vm_end != vma->vm_start + old_len)
1687 return (unsigned long) -EFAULT;
1689 if (vma->vm_flags & VM_MAYSHARE)
1690 return (unsigned long) -EPERM;
1692 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1693 return (unsigned long) -ENOMEM;
1695 /* all checks complete - do it */
1696 vma->vm_end = vma->vm_start + new_len;
1697 return vma->vm_start;
1699 EXPORT_SYMBOL(do_mremap);
1701 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1702 unsigned long, new_len, unsigned long, flags,
1703 unsigned long, new_addr)
1707 down_write(¤t->mm->mmap_sem);
1708 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1709 up_write(¤t->mm->mmap_sem);
1713 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1714 unsigned int foll_flags)
1719 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1720 unsigned long to, unsigned long size, pgprot_t prot)
1722 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1725 EXPORT_SYMBOL(remap_pfn_range);
1727 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1728 unsigned long pgoff)
1730 unsigned int size = vma->vm_end - vma->vm_start;
1732 if (!(vma->vm_flags & VM_USERMAP))
1735 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1736 vma->vm_end = vma->vm_start + size;
1740 EXPORT_SYMBOL(remap_vmalloc_range);
1742 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1746 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1747 unsigned long len, unsigned long pgoff, unsigned long flags)
1752 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1756 void unmap_mapping_range(struct address_space *mapping,
1757 loff_t const holebegin, loff_t const holelen,
1761 EXPORT_SYMBOL(unmap_mapping_range);
1764 * ask for an unmapped area at which to create a mapping on a file
1766 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1767 unsigned long len, unsigned long pgoff,
1768 unsigned long flags)
1770 unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1771 unsigned long, unsigned long);
1773 get_area = current->mm->get_unmapped_area;
1774 if (file && file->f_op && file->f_op->get_unmapped_area)
1775 get_area = file->f_op->get_unmapped_area;
1780 return get_area(file, addr, len, pgoff, flags);
1782 EXPORT_SYMBOL(get_unmapped_area);
1785 * Check that a process has enough memory to allocate a new virtual
1786 * mapping. 0 means there is enough memory for the allocation to
1787 * succeed and -ENOMEM implies there is not.
1789 * We currently support three overcommit policies, which are set via the
1790 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1792 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1793 * Additional code 2002 Jul 20 by Robert Love.
1795 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1797 * Note this is a helper function intended to be used by LSMs which
1798 * wish to use this logic.
1800 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1802 unsigned long free, allowed;
1804 vm_acct_memory(pages);
1807 * Sometimes we want to use more memory than we have
1809 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1812 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1815 free = global_page_state(NR_FILE_PAGES);
1816 free += nr_swap_pages;
1819 * Any slabs which are created with the
1820 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1821 * which are reclaimable, under pressure. The dentry
1822 * cache and most inode caches should fall into this
1824 free += global_page_state(NR_SLAB_RECLAIMABLE);
1827 * Leave the last 3% for root
1836 * nr_free_pages() is very expensive on large systems,
1837 * only call if we're about to fail.
1839 n = nr_free_pages();
1842 * Leave reserved pages. The pages are not for anonymous pages.
1844 if (n <= totalreserve_pages)
1847 n -= totalreserve_pages;
1850 * Leave the last 3% for root
1862 allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1864 * Leave the last 3% for root
1867 allowed -= allowed / 32;
1868 allowed += total_swap_pages;
1870 /* Don't let a single process grow too big:
1871 leave 3% of the size of this process for other processes */
1873 allowed -= mm->total_vm / 32;
1875 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1879 vm_unacct_memory(pages);
1884 int in_gate_area_no_task(unsigned long addr)
1889 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1894 EXPORT_SYMBOL(filemap_fault);
1897 * Access another process' address space.
1898 * - source/target buffer must be kernel space
1900 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1902 struct vm_area_struct *vma;
1903 struct mm_struct *mm;
1905 if (addr + len < addr)
1908 mm = get_task_mm(tsk);
1912 down_read(&mm->mmap_sem);
1914 /* the access must start within one of the target process's mappings */
1915 vma = find_vma(mm, addr);
1917 /* don't overrun this mapping */
1918 if (addr + len >= vma->vm_end)
1919 len = vma->vm_end - addr;
1921 /* only read or write mappings where it is permitted */
1922 if (write && vma->vm_flags & VM_MAYWRITE)
1923 len -= copy_to_user((void *) addr, buf, len);
1924 else if (!write && vma->vm_flags & VM_MAYREAD)
1925 len -= copy_from_user(buf, (void *) addr, len);
1932 up_read(&mm->mmap_sem);