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[cor_2_6_31.git] / mm / nommu.c
blob53cab10fece40a3f5835604e62754818de0e1e7c
1 /*
2 * linux/mm/nommu.c
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>
17 #include <linux/mm.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>
34 #include <asm/tlb.h>
35 #include <asm/tlbflush.h>
36 #include "internal.h"
38 static inline __attribute__((format(printf, 1, 2)))
39 void no_printk(const char *fmt, ...)
43 #if 0
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__)
50 #else
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__)
57 #endif
59 #include "internal.h"
61 void *high_memory;
62 struct page *mem_map;
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 /* amount of vm to protect from userspace access */
73 unsigned long mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
75 atomic_long_t mmap_pages_allocated;
77 EXPORT_SYMBOL(mem_map);
78 EXPORT_SYMBOL(num_physpages);
80 /* list of mapped, potentially shareable regions */
81 static struct kmem_cache *vm_region_jar;
82 struct rb_root nommu_region_tree = RB_ROOT;
83 DECLARE_RWSEM(nommu_region_sem);
85 struct vm_operations_struct generic_file_vm_ops = {
89 * Handle all mappings that got truncated by a "truncate()"
90 * system call.
92 * NOTE! We have to be ready to update the memory sharing
93 * between the file and the memory map for a potential last
94 * incomplete page. Ugly, but necessary.
96 int vmtruncate(struct inode *inode, loff_t offset)
98 struct address_space *mapping = inode->i_mapping;
99 unsigned long limit;
101 if (inode->i_size < offset)
102 goto do_expand;
103 i_size_write(inode, offset);
105 truncate_inode_pages(mapping, offset);
106 goto out_truncate;
108 do_expand:
109 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
110 if (limit != RLIM_INFINITY && offset > limit)
111 goto out_sig;
112 if (offset > inode->i_sb->s_maxbytes)
113 goto out;
114 i_size_write(inode, offset);
116 out_truncate:
117 if (inode->i_op->truncate)
118 inode->i_op->truncate(inode);
119 return 0;
120 out_sig:
121 send_sig(SIGXFSZ, current, 0);
122 out:
123 return -EFBIG;
126 EXPORT_SYMBOL(vmtruncate);
129 * Return the total memory allocated for this pointer, not
130 * just what the caller asked for.
132 * Doesn't have to be accurate, i.e. may have races.
134 unsigned int kobjsize(const void *objp)
136 struct page *page;
139 * If the object we have should not have ksize performed on it,
140 * return size of 0
142 if (!objp || !virt_addr_valid(objp))
143 return 0;
145 page = virt_to_head_page(objp);
148 * If the allocator sets PageSlab, we know the pointer came from
149 * kmalloc().
151 if (PageSlab(page))
152 return ksize(objp);
155 * If it's not a compound page, see if we have a matching VMA
156 * region. This test is intentionally done in reverse order,
157 * so if there's no VMA, we still fall through and hand back
158 * PAGE_SIZE for 0-order pages.
160 if (!PageCompound(page)) {
161 struct vm_area_struct *vma;
163 vma = find_vma(current->mm, (unsigned long)objp);
164 if (vma)
165 return vma->vm_end - vma->vm_start;
169 * The ksize() function is only guaranteed to work for pointers
170 * returned by kmalloc(). So handle arbitrary pointers here.
172 return PAGE_SIZE << compound_order(page);
175 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
176 unsigned long start, int nr_pages, int flags,
177 struct page **pages, struct vm_area_struct **vmas)
179 struct vm_area_struct *vma;
180 unsigned long vm_flags;
181 int i;
182 int write = !!(flags & GUP_FLAGS_WRITE);
183 int force = !!(flags & GUP_FLAGS_FORCE);
184 int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS);
186 /* calculate required read or write permissions.
187 * - if 'force' is set, we only require the "MAY" flags.
189 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
190 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
192 for (i = 0; i < nr_pages; i++) {
193 vma = find_vma(mm, start);
194 if (!vma)
195 goto finish_or_fault;
197 /* protect what we can, including chardevs */
198 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
199 (!ignore && !(vm_flags & vma->vm_flags)))
200 goto finish_or_fault;
202 if (pages) {
203 pages[i] = virt_to_page(start);
204 if (pages[i])
205 page_cache_get(pages[i]);
207 if (vmas)
208 vmas[i] = vma;
209 start += PAGE_SIZE;
212 return i;
214 finish_or_fault:
215 return i ? : -EFAULT;
220 * get a list of pages in an address range belonging to the specified process
221 * and indicate the VMA that covers each page
222 * - this is potentially dodgy as we may end incrementing the page count of a
223 * slab page or a secondary page from a compound page
224 * - don't permit access to VMAs that don't support it, such as I/O mappings
226 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
227 unsigned long start, int nr_pages, int write, int force,
228 struct page **pages, struct vm_area_struct **vmas)
230 int flags = 0;
232 if (write)
233 flags |= GUP_FLAGS_WRITE;
234 if (force)
235 flags |= GUP_FLAGS_FORCE;
237 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
239 EXPORT_SYMBOL(get_user_pages);
242 * follow_pfn - look up PFN at a user virtual address
243 * @vma: memory mapping
244 * @address: user virtual address
245 * @pfn: location to store found PFN
247 * Only IO mappings and raw PFN mappings are allowed.
249 * Returns zero and the pfn at @pfn on success, -ve otherwise.
251 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
252 unsigned long *pfn)
254 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
255 return -EINVAL;
257 *pfn = address >> PAGE_SHIFT;
258 return 0;
260 EXPORT_SYMBOL(follow_pfn);
262 DEFINE_RWLOCK(vmlist_lock);
263 struct vm_struct *vmlist;
265 void vfree(const void *addr)
267 kfree(addr);
269 EXPORT_SYMBOL(vfree);
271 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
274 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
275 * returns only a logical address.
277 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
279 EXPORT_SYMBOL(__vmalloc);
281 void *vmalloc_user(unsigned long size)
283 void *ret;
285 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
286 PAGE_KERNEL);
287 if (ret) {
288 struct vm_area_struct *vma;
290 down_write(&current->mm->mmap_sem);
291 vma = find_vma(current->mm, (unsigned long)ret);
292 if (vma)
293 vma->vm_flags |= VM_USERMAP;
294 up_write(&current->mm->mmap_sem);
297 return ret;
299 EXPORT_SYMBOL(vmalloc_user);
301 struct page *vmalloc_to_page(const void *addr)
303 return virt_to_page(addr);
305 EXPORT_SYMBOL(vmalloc_to_page);
307 unsigned long vmalloc_to_pfn(const void *addr)
309 return page_to_pfn(virt_to_page(addr));
311 EXPORT_SYMBOL(vmalloc_to_pfn);
313 long vread(char *buf, char *addr, unsigned long count)
315 memcpy(buf, addr, count);
316 return count;
319 long vwrite(char *buf, char *addr, unsigned long count)
321 /* Don't allow overflow */
322 if ((unsigned long) addr + count < count)
323 count = -(unsigned long) addr;
325 memcpy(addr, buf, count);
326 return(count);
330 * vmalloc - allocate virtually continguos memory
332 * @size: allocation size
334 * Allocate enough pages to cover @size from the page level
335 * allocator and map them into continguos kernel virtual space.
337 * For tight control over page level allocator and protection flags
338 * use __vmalloc() instead.
340 void *vmalloc(unsigned long size)
342 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
344 EXPORT_SYMBOL(vmalloc);
346 void *vmalloc_node(unsigned long size, int node)
348 return vmalloc(size);
350 EXPORT_SYMBOL(vmalloc_node);
352 #ifndef PAGE_KERNEL_EXEC
353 # define PAGE_KERNEL_EXEC PAGE_KERNEL
354 #endif
357 * vmalloc_exec - allocate virtually contiguous, executable memory
358 * @size: allocation size
360 * Kernel-internal function to allocate enough pages to cover @size
361 * the page level allocator and map them into contiguous and
362 * executable kernel virtual space.
364 * For tight control over page level allocator and protection flags
365 * use __vmalloc() instead.
368 void *vmalloc_exec(unsigned long size)
370 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
374 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
375 * @size: allocation size
377 * Allocate enough 32bit PA addressable pages to cover @size from the
378 * page level allocator and map them into continguos kernel virtual space.
380 void *vmalloc_32(unsigned long size)
382 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
384 EXPORT_SYMBOL(vmalloc_32);
387 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
388 * @size: allocation size
390 * The resulting memory area is 32bit addressable and zeroed so it can be
391 * mapped to userspace without leaking data.
393 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
394 * remap_vmalloc_range() are permissible.
396 void *vmalloc_32_user(unsigned long size)
399 * We'll have to sort out the ZONE_DMA bits for 64-bit,
400 * but for now this can simply use vmalloc_user() directly.
402 return vmalloc_user(size);
404 EXPORT_SYMBOL(vmalloc_32_user);
406 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
408 BUG();
409 return NULL;
411 EXPORT_SYMBOL(vmap);
413 void vunmap(const void *addr)
415 BUG();
417 EXPORT_SYMBOL(vunmap);
419 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
421 BUG();
422 return NULL;
424 EXPORT_SYMBOL(vm_map_ram);
426 void vm_unmap_ram(const void *mem, unsigned int count)
428 BUG();
430 EXPORT_SYMBOL(vm_unmap_ram);
432 void vm_unmap_aliases(void)
435 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
438 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
439 * have one.
441 void __attribute__((weak)) vmalloc_sync_all(void)
445 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
446 struct page *page)
448 return -EINVAL;
450 EXPORT_SYMBOL(vm_insert_page);
453 * sys_brk() for the most part doesn't need the global kernel
454 * lock, except when an application is doing something nasty
455 * like trying to un-brk an area that has already been mapped
456 * to a regular file. in this case, the unmapping will need
457 * to invoke file system routines that need the global lock.
459 SYSCALL_DEFINE1(brk, unsigned long, brk)
461 struct mm_struct *mm = current->mm;
463 if (brk < mm->start_brk || brk > mm->context.end_brk)
464 return mm->brk;
466 if (mm->brk == brk)
467 return mm->brk;
470 * Always allow shrinking brk
472 if (brk <= mm->brk) {
473 mm->brk = brk;
474 return brk;
478 * Ok, looks good - let it rip.
480 return mm->brk = brk;
484 * initialise the VMA and region record slabs
486 void __init mmap_init(void)
488 int ret;
490 ret = percpu_counter_init(&vm_committed_as, 0);
491 VM_BUG_ON(ret);
492 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
496 * validate the region tree
497 * - the caller must hold the region lock
499 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
500 static noinline void validate_nommu_regions(void)
502 struct vm_region *region, *last;
503 struct rb_node *p, *lastp;
505 lastp = rb_first(&nommu_region_tree);
506 if (!lastp)
507 return;
509 last = rb_entry(lastp, struct vm_region, vm_rb);
510 BUG_ON(unlikely(last->vm_end <= last->vm_start));
511 BUG_ON(unlikely(last->vm_top < last->vm_end));
513 while ((p = rb_next(lastp))) {
514 region = rb_entry(p, struct vm_region, vm_rb);
515 last = rb_entry(lastp, struct vm_region, vm_rb);
517 BUG_ON(unlikely(region->vm_end <= region->vm_start));
518 BUG_ON(unlikely(region->vm_top < region->vm_end));
519 BUG_ON(unlikely(region->vm_start < last->vm_top));
521 lastp = p;
524 #else
525 static void validate_nommu_regions(void)
528 #endif
531 * add a region into the global tree
533 static void add_nommu_region(struct vm_region *region)
535 struct vm_region *pregion;
536 struct rb_node **p, *parent;
538 validate_nommu_regions();
540 parent = NULL;
541 p = &nommu_region_tree.rb_node;
542 while (*p) {
543 parent = *p;
544 pregion = rb_entry(parent, struct vm_region, vm_rb);
545 if (region->vm_start < pregion->vm_start)
546 p = &(*p)->rb_left;
547 else if (region->vm_start > pregion->vm_start)
548 p = &(*p)->rb_right;
549 else if (pregion == region)
550 return;
551 else
552 BUG();
555 rb_link_node(&region->vm_rb, parent, p);
556 rb_insert_color(&region->vm_rb, &nommu_region_tree);
558 validate_nommu_regions();
562 * delete a region from the global tree
564 static void delete_nommu_region(struct vm_region *region)
566 BUG_ON(!nommu_region_tree.rb_node);
568 validate_nommu_regions();
569 rb_erase(&region->vm_rb, &nommu_region_tree);
570 validate_nommu_regions();
574 * free a contiguous series of pages
576 static void free_page_series(unsigned long from, unsigned long to)
578 for (; from < to; from += PAGE_SIZE) {
579 struct page *page = virt_to_page(from);
581 kdebug("- free %lx", from);
582 atomic_long_dec(&mmap_pages_allocated);
583 if (page_count(page) != 1)
584 kdebug("free page %p: refcount not one: %d",
585 page, page_count(page));
586 put_page(page);
591 * release a reference to a region
592 * - the caller must hold the region semaphore for writing, which this releases
593 * - the region may not have been added to the tree yet, in which case vm_top
594 * will equal vm_start
596 static void __put_nommu_region(struct vm_region *region)
597 __releases(nommu_region_sem)
599 kenter("%p{%d}", region, atomic_read(&region->vm_usage));
601 BUG_ON(!nommu_region_tree.rb_node);
603 if (atomic_dec_and_test(&region->vm_usage)) {
604 if (region->vm_top > region->vm_start)
605 delete_nommu_region(region);
606 up_write(&nommu_region_sem);
608 if (region->vm_file)
609 fput(region->vm_file);
611 /* IO memory and memory shared directly out of the pagecache
612 * from ramfs/tmpfs mustn't be released here */
613 if (region->vm_flags & VM_MAPPED_COPY) {
614 kdebug("free series");
615 free_page_series(region->vm_start, region->vm_top);
617 kmem_cache_free(vm_region_jar, region);
618 } else {
619 up_write(&nommu_region_sem);
624 * release a reference to a region
626 static void put_nommu_region(struct vm_region *region)
628 down_write(&nommu_region_sem);
629 __put_nommu_region(region);
633 * add a VMA into a process's mm_struct in the appropriate place in the list
634 * and tree and add to the address space's page tree also if not an anonymous
635 * page
636 * - should be called with mm->mmap_sem held writelocked
638 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
640 struct vm_area_struct *pvma, **pp;
641 struct address_space *mapping;
642 struct rb_node **p, *parent;
644 kenter(",%p", vma);
646 BUG_ON(!vma->vm_region);
648 mm->map_count++;
649 vma->vm_mm = mm;
651 /* add the VMA to the mapping */
652 if (vma->vm_file) {
653 mapping = vma->vm_file->f_mapping;
655 flush_dcache_mmap_lock(mapping);
656 vma_prio_tree_insert(vma, &mapping->i_mmap);
657 flush_dcache_mmap_unlock(mapping);
660 /* add the VMA to the tree */
661 parent = NULL;
662 p = &mm->mm_rb.rb_node;
663 while (*p) {
664 parent = *p;
665 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
667 /* sort by: start addr, end addr, VMA struct addr in that order
668 * (the latter is necessary as we may get identical VMAs) */
669 if (vma->vm_start < pvma->vm_start)
670 p = &(*p)->rb_left;
671 else if (vma->vm_start > pvma->vm_start)
672 p = &(*p)->rb_right;
673 else if (vma->vm_end < pvma->vm_end)
674 p = &(*p)->rb_left;
675 else if (vma->vm_end > pvma->vm_end)
676 p = &(*p)->rb_right;
677 else if (vma < pvma)
678 p = &(*p)->rb_left;
679 else if (vma > pvma)
680 p = &(*p)->rb_right;
681 else
682 BUG();
685 rb_link_node(&vma->vm_rb, parent, p);
686 rb_insert_color(&vma->vm_rb, &mm->mm_rb);
688 /* add VMA to the VMA list also */
689 for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
690 if (pvma->vm_start > vma->vm_start)
691 break;
692 if (pvma->vm_start < vma->vm_start)
693 continue;
694 if (pvma->vm_end < vma->vm_end)
695 break;
698 vma->vm_next = *pp;
699 *pp = vma;
703 * delete a VMA from its owning mm_struct and address space
705 static void delete_vma_from_mm(struct vm_area_struct *vma)
707 struct vm_area_struct **pp;
708 struct address_space *mapping;
709 struct mm_struct *mm = vma->vm_mm;
711 kenter("%p", vma);
713 mm->map_count--;
714 if (mm->mmap_cache == vma)
715 mm->mmap_cache = NULL;
717 /* remove the VMA from the mapping */
718 if (vma->vm_file) {
719 mapping = vma->vm_file->f_mapping;
721 flush_dcache_mmap_lock(mapping);
722 vma_prio_tree_remove(vma, &mapping->i_mmap);
723 flush_dcache_mmap_unlock(mapping);
726 /* remove from the MM's tree and list */
727 rb_erase(&vma->vm_rb, &mm->mm_rb);
728 for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
729 if (*pp == vma) {
730 *pp = vma->vm_next;
731 break;
735 vma->vm_mm = NULL;
739 * destroy a VMA record
741 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
743 kenter("%p", vma);
744 if (vma->vm_ops && vma->vm_ops->close)
745 vma->vm_ops->close(vma);
746 if (vma->vm_file) {
747 fput(vma->vm_file);
748 if (vma->vm_flags & VM_EXECUTABLE)
749 removed_exe_file_vma(mm);
751 put_nommu_region(vma->vm_region);
752 kmem_cache_free(vm_area_cachep, vma);
756 * look up the first VMA in which addr resides, NULL if none
757 * - should be called with mm->mmap_sem at least held readlocked
759 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
761 struct vm_area_struct *vma;
762 struct rb_node *n = mm->mm_rb.rb_node;
764 /* check the cache first */
765 vma = mm->mmap_cache;
766 if (vma && vma->vm_start <= addr && vma->vm_end > addr)
767 return vma;
769 /* trawl the tree (there may be multiple mappings in which addr
770 * resides) */
771 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
772 vma = rb_entry(n, struct vm_area_struct, vm_rb);
773 if (vma->vm_start > addr)
774 return NULL;
775 if (vma->vm_end > addr) {
776 mm->mmap_cache = vma;
777 return vma;
781 return NULL;
783 EXPORT_SYMBOL(find_vma);
786 * find a VMA
787 * - we don't extend stack VMAs under NOMMU conditions
789 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
791 return find_vma(mm, addr);
795 * expand a stack to a given address
796 * - not supported under NOMMU conditions
798 int expand_stack(struct vm_area_struct *vma, unsigned long address)
800 return -ENOMEM;
804 * look up the first VMA exactly that exactly matches addr
805 * - should be called with mm->mmap_sem at least held readlocked
807 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
808 unsigned long addr,
809 unsigned long len)
811 struct vm_area_struct *vma;
812 struct rb_node *n = mm->mm_rb.rb_node;
813 unsigned long end = addr + len;
815 /* check the cache first */
816 vma = mm->mmap_cache;
817 if (vma && vma->vm_start == addr && vma->vm_end == end)
818 return vma;
820 /* trawl the tree (there may be multiple mappings in which addr
821 * resides) */
822 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
823 vma = rb_entry(n, struct vm_area_struct, vm_rb);
824 if (vma->vm_start < addr)
825 continue;
826 if (vma->vm_start > addr)
827 return NULL;
828 if (vma->vm_end == end) {
829 mm->mmap_cache = vma;
830 return vma;
834 return NULL;
838 * determine whether a mapping should be permitted and, if so, what sort of
839 * mapping we're capable of supporting
841 static int validate_mmap_request(struct file *file,
842 unsigned long addr,
843 unsigned long len,
844 unsigned long prot,
845 unsigned long flags,
846 unsigned long pgoff,
847 unsigned long *_capabilities)
849 unsigned long capabilities, rlen;
850 unsigned long reqprot = prot;
851 int ret;
853 /* do the simple checks first */
854 if (flags & MAP_FIXED || addr) {
855 printk(KERN_DEBUG
856 "%d: Can't do fixed-address/overlay mmap of RAM\n",
857 current->pid);
858 return -EINVAL;
861 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
862 (flags & MAP_TYPE) != MAP_SHARED)
863 return -EINVAL;
865 if (!len)
866 return -EINVAL;
868 /* Careful about overflows.. */
869 rlen = PAGE_ALIGN(len);
870 if (!rlen || rlen > TASK_SIZE)
871 return -ENOMEM;
873 /* offset overflow? */
874 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
875 return -EOVERFLOW;
877 if (file) {
878 /* validate file mapping requests */
879 struct address_space *mapping;
881 /* files must support mmap */
882 if (!file->f_op || !file->f_op->mmap)
883 return -ENODEV;
885 /* work out if what we've got could possibly be shared
886 * - we support chardevs that provide their own "memory"
887 * - we support files/blockdevs that are memory backed
889 mapping = file->f_mapping;
890 if (!mapping)
891 mapping = file->f_path.dentry->d_inode->i_mapping;
893 capabilities = 0;
894 if (mapping && mapping->backing_dev_info)
895 capabilities = mapping->backing_dev_info->capabilities;
897 if (!capabilities) {
898 /* no explicit capabilities set, so assume some
899 * defaults */
900 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
901 case S_IFREG:
902 case S_IFBLK:
903 capabilities = BDI_CAP_MAP_COPY;
904 break;
906 case S_IFCHR:
907 capabilities =
908 BDI_CAP_MAP_DIRECT |
909 BDI_CAP_READ_MAP |
910 BDI_CAP_WRITE_MAP;
911 break;
913 default:
914 return -EINVAL;
918 /* eliminate any capabilities that we can't support on this
919 * device */
920 if (!file->f_op->get_unmapped_area)
921 capabilities &= ~BDI_CAP_MAP_DIRECT;
922 if (!file->f_op->read)
923 capabilities &= ~BDI_CAP_MAP_COPY;
925 if (flags & MAP_SHARED) {
926 /* do checks for writing, appending and locking */
927 if ((prot & PROT_WRITE) &&
928 !(file->f_mode & FMODE_WRITE))
929 return -EACCES;
931 if (IS_APPEND(file->f_path.dentry->d_inode) &&
932 (file->f_mode & FMODE_WRITE))
933 return -EACCES;
935 if (locks_verify_locked(file->f_path.dentry->d_inode))
936 return -EAGAIN;
938 if (!(capabilities & BDI_CAP_MAP_DIRECT))
939 return -ENODEV;
941 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
942 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
943 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
945 printk("MAP_SHARED not completely supported on !MMU\n");
946 return -EINVAL;
949 /* we mustn't privatise shared mappings */
950 capabilities &= ~BDI_CAP_MAP_COPY;
952 else {
953 /* we're going to read the file into private memory we
954 * allocate */
955 if (!(capabilities & BDI_CAP_MAP_COPY))
956 return -ENODEV;
958 /* we don't permit a private writable mapping to be
959 * shared with the backing device */
960 if (prot & PROT_WRITE)
961 capabilities &= ~BDI_CAP_MAP_DIRECT;
964 /* handle executable mappings and implied executable
965 * mappings */
966 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
967 if (prot & PROT_EXEC)
968 return -EPERM;
970 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
971 /* handle implication of PROT_EXEC by PROT_READ */
972 if (current->personality & READ_IMPLIES_EXEC) {
973 if (capabilities & BDI_CAP_EXEC_MAP)
974 prot |= PROT_EXEC;
977 else if ((prot & PROT_READ) &&
978 (prot & PROT_EXEC) &&
979 !(capabilities & BDI_CAP_EXEC_MAP)
981 /* backing file is not executable, try to copy */
982 capabilities &= ~BDI_CAP_MAP_DIRECT;
985 else {
986 /* anonymous mappings are always memory backed and can be
987 * privately mapped
989 capabilities = BDI_CAP_MAP_COPY;
991 /* handle PROT_EXEC implication by PROT_READ */
992 if ((prot & PROT_READ) &&
993 (current->personality & READ_IMPLIES_EXEC))
994 prot |= PROT_EXEC;
997 /* allow the security API to have its say */
998 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
999 if (ret < 0)
1000 return ret;
1002 /* looks okay */
1003 *_capabilities = capabilities;
1004 return 0;
1008 * we've determined that we can make the mapping, now translate what we
1009 * now know into VMA flags
1011 static unsigned long determine_vm_flags(struct file *file,
1012 unsigned long prot,
1013 unsigned long flags,
1014 unsigned long capabilities)
1016 unsigned long vm_flags;
1018 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1019 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1020 /* vm_flags |= mm->def_flags; */
1022 if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1023 /* attempt to share read-only copies of mapped file chunks */
1024 if (file && !(prot & PROT_WRITE))
1025 vm_flags |= VM_MAYSHARE;
1027 else {
1028 /* overlay a shareable mapping on the backing device or inode
1029 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1030 * romfs/cramfs */
1031 if (flags & MAP_SHARED)
1032 vm_flags |= VM_MAYSHARE | VM_SHARED;
1033 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
1034 vm_flags |= VM_MAYSHARE;
1037 /* refuse to let anyone share private mappings with this process if
1038 * it's being traced - otherwise breakpoints set in it may interfere
1039 * with another untraced process
1041 if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
1042 vm_flags &= ~VM_MAYSHARE;
1044 return vm_flags;
1048 * set up a shared mapping on a file (the driver or filesystem provides and
1049 * pins the storage)
1051 static int do_mmap_shared_file(struct vm_area_struct *vma)
1053 int ret;
1055 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1056 if (ret == 0) {
1057 vma->vm_region->vm_top = vma->vm_region->vm_end;
1058 return ret;
1060 if (ret != -ENOSYS)
1061 return ret;
1063 /* getting an ENOSYS error indicates that direct mmap isn't
1064 * possible (as opposed to tried but failed) so we'll fall
1065 * through to making a private copy of the data and mapping
1066 * that if we can */
1067 return -ENODEV;
1071 * set up a private mapping or an anonymous shared mapping
1073 static int do_mmap_private(struct vm_area_struct *vma,
1074 struct vm_region *region,
1075 unsigned long len)
1077 struct page *pages;
1078 unsigned long total, point, n, rlen;
1079 void *base;
1080 int ret, order;
1082 /* invoke the file's mapping function so that it can keep track of
1083 * shared mappings on devices or memory
1084 * - VM_MAYSHARE will be set if it may attempt to share
1086 if (vma->vm_file) {
1087 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1088 if (ret == 0) {
1089 /* shouldn't return success if we're not sharing */
1090 BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1091 vma->vm_region->vm_top = vma->vm_region->vm_end;
1092 return ret;
1094 if (ret != -ENOSYS)
1095 return ret;
1097 /* getting an ENOSYS error indicates that direct mmap isn't
1098 * possible (as opposed to tried but failed) so we'll try to
1099 * make a private copy of the data and map that instead */
1102 rlen = PAGE_ALIGN(len);
1104 /* allocate some memory to hold the mapping
1105 * - note that this may not return a page-aligned address if the object
1106 * we're allocating is smaller than a page
1108 order = get_order(rlen);
1109 kdebug("alloc order %d for %lx", order, len);
1111 pages = alloc_pages(GFP_KERNEL, order);
1112 if (!pages)
1113 goto enomem;
1115 total = 1 << order;
1116 atomic_long_add(total, &mmap_pages_allocated);
1118 point = rlen >> PAGE_SHIFT;
1120 /* we allocated a power-of-2 sized page set, so we may want to trim off
1121 * the excess */
1122 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1123 while (total > point) {
1124 order = ilog2(total - point);
1125 n = 1 << order;
1126 kdebug("shave %lu/%lu @%lu", n, total - point, total);
1127 atomic_long_sub(n, &mmap_pages_allocated);
1128 total -= n;
1129 set_page_refcounted(pages + total);
1130 __free_pages(pages + total, order);
1134 for (point = 1; point < total; point++)
1135 set_page_refcounted(&pages[point]);
1137 base = page_address(pages);
1138 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1139 region->vm_start = (unsigned long) base;
1140 region->vm_end = region->vm_start + rlen;
1141 region->vm_top = region->vm_start + (total << PAGE_SHIFT);
1143 vma->vm_start = region->vm_start;
1144 vma->vm_end = region->vm_start + len;
1146 if (vma->vm_file) {
1147 /* read the contents of a file into the copy */
1148 mm_segment_t old_fs;
1149 loff_t fpos;
1151 fpos = vma->vm_pgoff;
1152 fpos <<= PAGE_SHIFT;
1154 old_fs = get_fs();
1155 set_fs(KERNEL_DS);
1156 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
1157 set_fs(old_fs);
1159 if (ret < 0)
1160 goto error_free;
1162 /* clear the last little bit */
1163 if (ret < rlen)
1164 memset(base + ret, 0, rlen - ret);
1166 } else {
1167 /* if it's an anonymous mapping, then just clear it */
1168 memset(base, 0, rlen);
1171 return 0;
1173 error_free:
1174 free_page_series(region->vm_start, region->vm_end);
1175 region->vm_start = vma->vm_start = 0;
1176 region->vm_end = vma->vm_end = 0;
1177 region->vm_top = 0;
1178 return ret;
1180 enomem:
1181 printk("Allocation of length %lu from process %d (%s) failed\n",
1182 len, current->pid, current->comm);
1183 show_free_areas();
1184 return -ENOMEM;
1188 * handle mapping creation for uClinux
1190 unsigned long do_mmap_pgoff(struct file *file,
1191 unsigned long addr,
1192 unsigned long len,
1193 unsigned long prot,
1194 unsigned long flags,
1195 unsigned long pgoff)
1197 struct vm_area_struct *vma;
1198 struct vm_region *region;
1199 struct rb_node *rb;
1200 unsigned long capabilities, vm_flags, result;
1201 int ret;
1203 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1205 if (!(flags & MAP_FIXED))
1206 addr = round_hint_to_min(addr);
1208 /* decide whether we should attempt the mapping, and if so what sort of
1209 * mapping */
1210 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1211 &capabilities);
1212 if (ret < 0) {
1213 kleave(" = %d [val]", ret);
1214 return ret;
1217 /* we've determined that we can make the mapping, now translate what we
1218 * now know into VMA flags */
1219 vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1221 /* we're going to need to record the mapping */
1222 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1223 if (!region)
1224 goto error_getting_region;
1226 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1227 if (!vma)
1228 goto error_getting_vma;
1230 atomic_set(&region->vm_usage, 1);
1231 region->vm_flags = vm_flags;
1232 region->vm_pgoff = pgoff;
1234 INIT_LIST_HEAD(&vma->anon_vma_node);
1235 vma->vm_flags = vm_flags;
1236 vma->vm_pgoff = pgoff;
1238 if (file) {
1239 region->vm_file = file;
1240 get_file(file);
1241 vma->vm_file = file;
1242 get_file(file);
1243 if (vm_flags & VM_EXECUTABLE) {
1244 added_exe_file_vma(current->mm);
1245 vma->vm_mm = current->mm;
1249 down_write(&nommu_region_sem);
1251 /* if we want to share, we need to check for regions created by other
1252 * mmap() calls that overlap with our proposed mapping
1253 * - we can only share with a superset match on most regular files
1254 * - shared mappings on character devices and memory backed files are
1255 * permitted to overlap inexactly as far as we are concerned for in
1256 * these cases, sharing is handled in the driver or filesystem rather
1257 * than here
1259 if (vm_flags & VM_MAYSHARE) {
1260 struct vm_region *pregion;
1261 unsigned long pglen, rpglen, pgend, rpgend, start;
1263 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1264 pgend = pgoff + pglen;
1266 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1267 pregion = rb_entry(rb, struct vm_region, vm_rb);
1269 if (!(pregion->vm_flags & VM_MAYSHARE))
1270 continue;
1272 /* search for overlapping mappings on the same file */
1273 if (pregion->vm_file->f_path.dentry->d_inode !=
1274 file->f_path.dentry->d_inode)
1275 continue;
1277 if (pregion->vm_pgoff >= pgend)
1278 continue;
1280 rpglen = pregion->vm_end - pregion->vm_start;
1281 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1282 rpgend = pregion->vm_pgoff + rpglen;
1283 if (pgoff >= rpgend)
1284 continue;
1286 /* handle inexactly overlapping matches between
1287 * mappings */
1288 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1289 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1290 /* new mapping is not a subset of the region */
1291 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1292 goto sharing_violation;
1293 continue;
1296 /* we've found a region we can share */
1297 atomic_inc(&pregion->vm_usage);
1298 vma->vm_region = pregion;
1299 start = pregion->vm_start;
1300 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1301 vma->vm_start = start;
1302 vma->vm_end = start + len;
1304 if (pregion->vm_flags & VM_MAPPED_COPY) {
1305 kdebug("share copy");
1306 vma->vm_flags |= VM_MAPPED_COPY;
1307 } else {
1308 kdebug("share mmap");
1309 ret = do_mmap_shared_file(vma);
1310 if (ret < 0) {
1311 vma->vm_region = NULL;
1312 vma->vm_start = 0;
1313 vma->vm_end = 0;
1314 atomic_dec(&pregion->vm_usage);
1315 pregion = NULL;
1316 goto error_just_free;
1319 fput(region->vm_file);
1320 kmem_cache_free(vm_region_jar, region);
1321 region = pregion;
1322 result = start;
1323 goto share;
1326 /* obtain the address at which to make a shared mapping
1327 * - this is the hook for quasi-memory character devices to
1328 * tell us the location of a shared mapping
1330 if (file && file->f_op->get_unmapped_area) {
1331 addr = file->f_op->get_unmapped_area(file, addr, len,
1332 pgoff, flags);
1333 if (IS_ERR((void *) addr)) {
1334 ret = addr;
1335 if (ret != (unsigned long) -ENOSYS)
1336 goto error_just_free;
1338 /* the driver refused to tell us where to site
1339 * the mapping so we'll have to attempt to copy
1340 * it */
1341 ret = (unsigned long) -ENODEV;
1342 if (!(capabilities & BDI_CAP_MAP_COPY))
1343 goto error_just_free;
1345 capabilities &= ~BDI_CAP_MAP_DIRECT;
1346 } else {
1347 vma->vm_start = region->vm_start = addr;
1348 vma->vm_end = region->vm_end = addr + len;
1353 vma->vm_region = region;
1355 /* set up the mapping */
1356 if (file && vma->vm_flags & VM_SHARED)
1357 ret = do_mmap_shared_file(vma);
1358 else
1359 ret = do_mmap_private(vma, region, len);
1360 if (ret < 0)
1361 goto error_put_region;
1363 add_nommu_region(region);
1365 /* okay... we have a mapping; now we have to register it */
1366 result = vma->vm_start;
1368 current->mm->total_vm += len >> PAGE_SHIFT;
1370 share:
1371 add_vma_to_mm(current->mm, vma);
1373 up_write(&nommu_region_sem);
1375 if (prot & PROT_EXEC)
1376 flush_icache_range(result, result + len);
1378 kleave(" = %lx", result);
1379 return result;
1381 error_put_region:
1382 __put_nommu_region(region);
1383 if (vma) {
1384 if (vma->vm_file) {
1385 fput(vma->vm_file);
1386 if (vma->vm_flags & VM_EXECUTABLE)
1387 removed_exe_file_vma(vma->vm_mm);
1389 kmem_cache_free(vm_area_cachep, vma);
1391 kleave(" = %d [pr]", ret);
1392 return ret;
1394 error_just_free:
1395 up_write(&nommu_region_sem);
1396 error:
1397 fput(region->vm_file);
1398 kmem_cache_free(vm_region_jar, region);
1399 fput(vma->vm_file);
1400 if (vma->vm_flags & VM_EXECUTABLE)
1401 removed_exe_file_vma(vma->vm_mm);
1402 kmem_cache_free(vm_area_cachep, vma);
1403 kleave(" = %d", ret);
1404 return ret;
1406 sharing_violation:
1407 up_write(&nommu_region_sem);
1408 printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1409 ret = -EINVAL;
1410 goto error;
1412 error_getting_vma:
1413 kmem_cache_free(vm_region_jar, region);
1414 printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1415 " from process %d failed\n",
1416 len, current->pid);
1417 show_free_areas();
1418 return -ENOMEM;
1420 error_getting_region:
1421 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1422 " from process %d failed\n",
1423 len, current->pid);
1424 show_free_areas();
1425 return -ENOMEM;
1427 EXPORT_SYMBOL(do_mmap_pgoff);
1430 * split a vma into two pieces at address 'addr', a new vma is allocated either
1431 * for the first part or the tail.
1433 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1434 unsigned long addr, int new_below)
1436 struct vm_area_struct *new;
1437 struct vm_region *region;
1438 unsigned long npages;
1440 kenter("");
1442 /* we're only permitted to split anonymous regions that have a single
1443 * owner */
1444 if (vma->vm_file ||
1445 atomic_read(&vma->vm_region->vm_usage) != 1)
1446 return -ENOMEM;
1448 if (mm->map_count >= sysctl_max_map_count)
1449 return -ENOMEM;
1451 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1452 if (!region)
1453 return -ENOMEM;
1455 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1456 if (!new) {
1457 kmem_cache_free(vm_region_jar, region);
1458 return -ENOMEM;
1461 /* most fields are the same, copy all, and then fixup */
1462 *new = *vma;
1463 *region = *vma->vm_region;
1464 new->vm_region = region;
1466 npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1468 if (new_below) {
1469 region->vm_top = region->vm_end = new->vm_end = addr;
1470 } else {
1471 region->vm_start = new->vm_start = addr;
1472 region->vm_pgoff = new->vm_pgoff += npages;
1475 if (new->vm_ops && new->vm_ops->open)
1476 new->vm_ops->open(new);
1478 delete_vma_from_mm(vma);
1479 down_write(&nommu_region_sem);
1480 delete_nommu_region(vma->vm_region);
1481 if (new_below) {
1482 vma->vm_region->vm_start = vma->vm_start = addr;
1483 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1484 } else {
1485 vma->vm_region->vm_end = vma->vm_end = addr;
1486 vma->vm_region->vm_top = addr;
1488 add_nommu_region(vma->vm_region);
1489 add_nommu_region(new->vm_region);
1490 up_write(&nommu_region_sem);
1491 add_vma_to_mm(mm, vma);
1492 add_vma_to_mm(mm, new);
1493 return 0;
1497 * shrink a VMA by removing the specified chunk from either the beginning or
1498 * the end
1500 static int shrink_vma(struct mm_struct *mm,
1501 struct vm_area_struct *vma,
1502 unsigned long from, unsigned long to)
1504 struct vm_region *region;
1506 kenter("");
1508 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1509 * and list */
1510 delete_vma_from_mm(vma);
1511 if (from > vma->vm_start)
1512 vma->vm_end = from;
1513 else
1514 vma->vm_start = to;
1515 add_vma_to_mm(mm, vma);
1517 /* cut the backing region down to size */
1518 region = vma->vm_region;
1519 BUG_ON(atomic_read(&region->vm_usage) != 1);
1521 down_write(&nommu_region_sem);
1522 delete_nommu_region(region);
1523 if (from > region->vm_start) {
1524 to = region->vm_top;
1525 region->vm_top = region->vm_end = from;
1526 } else {
1527 region->vm_start = to;
1529 add_nommu_region(region);
1530 up_write(&nommu_region_sem);
1532 free_page_series(from, to);
1533 return 0;
1537 * release a mapping
1538 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1539 * VMA, though it need not cover the whole VMA
1541 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1543 struct vm_area_struct *vma;
1544 struct rb_node *rb;
1545 unsigned long end = start + len;
1546 int ret;
1548 kenter(",%lx,%zx", start, len);
1550 if (len == 0)
1551 return -EINVAL;
1553 /* find the first potentially overlapping VMA */
1554 vma = find_vma(mm, start);
1555 if (!vma) {
1556 static int limit = 0;
1557 if (limit < 5) {
1558 printk(KERN_WARNING
1559 "munmap of memory not mmapped by process %d"
1560 " (%s): 0x%lx-0x%lx\n",
1561 current->pid, current->comm,
1562 start, start + len - 1);
1563 limit++;
1565 return -EINVAL;
1568 /* we're allowed to split an anonymous VMA but not a file-backed one */
1569 if (vma->vm_file) {
1570 do {
1571 if (start > vma->vm_start) {
1572 kleave(" = -EINVAL [miss]");
1573 return -EINVAL;
1575 if (end == vma->vm_end)
1576 goto erase_whole_vma;
1577 rb = rb_next(&vma->vm_rb);
1578 vma = rb_entry(rb, struct vm_area_struct, vm_rb);
1579 } while (rb);
1580 kleave(" = -EINVAL [split file]");
1581 return -EINVAL;
1582 } else {
1583 /* the chunk must be a subset of the VMA found */
1584 if (start == vma->vm_start && end == vma->vm_end)
1585 goto erase_whole_vma;
1586 if (start < vma->vm_start || end > vma->vm_end) {
1587 kleave(" = -EINVAL [superset]");
1588 return -EINVAL;
1590 if (start & ~PAGE_MASK) {
1591 kleave(" = -EINVAL [unaligned start]");
1592 return -EINVAL;
1594 if (end != vma->vm_end && end & ~PAGE_MASK) {
1595 kleave(" = -EINVAL [unaligned split]");
1596 return -EINVAL;
1598 if (start != vma->vm_start && end != vma->vm_end) {
1599 ret = split_vma(mm, vma, start, 1);
1600 if (ret < 0) {
1601 kleave(" = %d [split]", ret);
1602 return ret;
1605 return shrink_vma(mm, vma, start, end);
1608 erase_whole_vma:
1609 delete_vma_from_mm(vma);
1610 delete_vma(mm, vma);
1611 kleave(" = 0");
1612 return 0;
1614 EXPORT_SYMBOL(do_munmap);
1616 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1618 int ret;
1619 struct mm_struct *mm = current->mm;
1621 down_write(&mm->mmap_sem);
1622 ret = do_munmap(mm, addr, len);
1623 up_write(&mm->mmap_sem);
1624 return ret;
1628 * release all the mappings made in a process's VM space
1630 void exit_mmap(struct mm_struct *mm)
1632 struct vm_area_struct *vma;
1634 if (!mm)
1635 return;
1637 kenter("");
1639 mm->total_vm = 0;
1641 while ((vma = mm->mmap)) {
1642 mm->mmap = vma->vm_next;
1643 delete_vma_from_mm(vma);
1644 delete_vma(mm, vma);
1647 kleave("");
1650 unsigned long do_brk(unsigned long addr, unsigned long len)
1652 return -ENOMEM;
1656 * expand (or shrink) an existing mapping, potentially moving it at the same
1657 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1659 * under NOMMU conditions, we only permit changing a mapping's size, and only
1660 * as long as it stays within the region allocated by do_mmap_private() and the
1661 * block is not shareable
1663 * MREMAP_FIXED is not supported under NOMMU conditions
1665 unsigned long do_mremap(unsigned long addr,
1666 unsigned long old_len, unsigned long new_len,
1667 unsigned long flags, unsigned long new_addr)
1669 struct vm_area_struct *vma;
1671 /* insanity checks first */
1672 if (old_len == 0 || new_len == 0)
1673 return (unsigned long) -EINVAL;
1675 if (addr & ~PAGE_MASK)
1676 return -EINVAL;
1678 if (flags & MREMAP_FIXED && new_addr != addr)
1679 return (unsigned long) -EINVAL;
1681 vma = find_vma_exact(current->mm, addr, old_len);
1682 if (!vma)
1683 return (unsigned long) -EINVAL;
1685 if (vma->vm_end != vma->vm_start + old_len)
1686 return (unsigned long) -EFAULT;
1688 if (vma->vm_flags & VM_MAYSHARE)
1689 return (unsigned long) -EPERM;
1691 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1692 return (unsigned long) -ENOMEM;
1694 /* all checks complete - do it */
1695 vma->vm_end = vma->vm_start + new_len;
1696 return vma->vm_start;
1698 EXPORT_SYMBOL(do_mremap);
1700 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1701 unsigned long, new_len, unsigned long, flags,
1702 unsigned long, new_addr)
1704 unsigned long ret;
1706 down_write(&current->mm->mmap_sem);
1707 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1708 up_write(&current->mm->mmap_sem);
1709 return ret;
1712 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1713 unsigned int foll_flags)
1715 return NULL;
1718 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1719 unsigned long to, unsigned long size, pgprot_t prot)
1721 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1722 return 0;
1724 EXPORT_SYMBOL(remap_pfn_range);
1726 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1727 unsigned long pgoff)
1729 unsigned int size = vma->vm_end - vma->vm_start;
1731 if (!(vma->vm_flags & VM_USERMAP))
1732 return -EINVAL;
1734 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1735 vma->vm_end = vma->vm_start + size;
1737 return 0;
1739 EXPORT_SYMBOL(remap_vmalloc_range);
1741 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1745 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1746 unsigned long len, unsigned long pgoff, unsigned long flags)
1748 return -ENOMEM;
1751 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1755 void unmap_mapping_range(struct address_space *mapping,
1756 loff_t const holebegin, loff_t const holelen,
1757 int even_cows)
1760 EXPORT_SYMBOL(unmap_mapping_range);
1763 * ask for an unmapped area at which to create a mapping on a file
1765 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1766 unsigned long len, unsigned long pgoff,
1767 unsigned long flags)
1769 unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1770 unsigned long, unsigned long);
1772 get_area = current->mm->get_unmapped_area;
1773 if (file && file->f_op && file->f_op->get_unmapped_area)
1774 get_area = file->f_op->get_unmapped_area;
1776 if (!get_area)
1777 return -ENOSYS;
1779 return get_area(file, addr, len, pgoff, flags);
1781 EXPORT_SYMBOL(get_unmapped_area);
1784 * Check that a process has enough memory to allocate a new virtual
1785 * mapping. 0 means there is enough memory for the allocation to
1786 * succeed and -ENOMEM implies there is not.
1788 * We currently support three overcommit policies, which are set via the
1789 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1791 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1792 * Additional code 2002 Jul 20 by Robert Love.
1794 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1796 * Note this is a helper function intended to be used by LSMs which
1797 * wish to use this logic.
1799 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1801 unsigned long free, allowed;
1803 vm_acct_memory(pages);
1806 * Sometimes we want to use more memory than we have
1808 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1809 return 0;
1811 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1812 unsigned long n;
1814 free = global_page_state(NR_FILE_PAGES);
1815 free += nr_swap_pages;
1818 * Any slabs which are created with the
1819 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1820 * which are reclaimable, under pressure. The dentry
1821 * cache and most inode caches should fall into this
1823 free += global_page_state(NR_SLAB_RECLAIMABLE);
1826 * Leave the last 3% for root
1828 if (!cap_sys_admin)
1829 free -= free / 32;
1831 if (free > pages)
1832 return 0;
1835 * nr_free_pages() is very expensive on large systems,
1836 * only call if we're about to fail.
1838 n = nr_free_pages();
1841 * Leave reserved pages. The pages are not for anonymous pages.
1843 if (n <= totalreserve_pages)
1844 goto error;
1845 else
1846 n -= totalreserve_pages;
1849 * Leave the last 3% for root
1851 if (!cap_sys_admin)
1852 n -= n / 32;
1853 free += n;
1855 if (free > pages)
1856 return 0;
1858 goto error;
1861 allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1863 * Leave the last 3% for root
1865 if (!cap_sys_admin)
1866 allowed -= allowed / 32;
1867 allowed += total_swap_pages;
1869 /* Don't let a single process grow too big:
1870 leave 3% of the size of this process for other processes */
1871 if (mm)
1872 allowed -= mm->total_vm / 32;
1874 if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1875 return 0;
1877 error:
1878 vm_unacct_memory(pages);
1880 return -ENOMEM;
1883 int in_gate_area_no_task(unsigned long addr)
1885 return 0;
1888 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1890 BUG();
1891 return 0;
1893 EXPORT_SYMBOL(filemap_fault);
1896 * Access another process' address space.
1897 * - source/target buffer must be kernel space
1899 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1901 struct vm_area_struct *vma;
1902 struct mm_struct *mm;
1904 if (addr + len < addr)
1905 return 0;
1907 mm = get_task_mm(tsk);
1908 if (!mm)
1909 return 0;
1911 down_read(&mm->mmap_sem);
1913 /* the access must start within one of the target process's mappings */
1914 vma = find_vma(mm, addr);
1915 if (vma) {
1916 /* don't overrun this mapping */
1917 if (addr + len >= vma->vm_end)
1918 len = vma->vm_end - addr;
1920 /* only read or write mappings where it is permitted */
1921 if (write && vma->vm_flags & VM_MAYWRITE)
1922 len -= copy_to_user((void *) addr, buf, len);
1923 else if (!write && vma->vm_flags & VM_MAYREAD)
1924 len -= copy_from_user(buf, (void *) addr, len);
1925 else
1926 len = 0;
1927 } else {
1928 len = 0;
1931 up_read(&mm->mmap_sem);
1932 mmput(mm);
1933 return len;