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) 2007-2010 Paul Mundt <lethal@linux-sh.org>
16 #include <linux/export.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/blkdev.h>
26 #include <linux/backing-dev.h>
27 #include <linux/mount.h>
28 #include <linux/personality.h>
29 #include <linux/security.h>
30 #include <linux/syscalls.h>
31 #include <linux/audit.h>
32 #include <linux/sched/sysctl.h>
34 #include <asm/uaccess.h>
36 #include <asm/tlbflush.h>
37 #include <asm/mmu_context.h>
41 #define kenter(FMT, ...) \
42 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
43 #define kleave(FMT, ...) \
44 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
45 #define kdebug(FMT, ...) \
46 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
48 #define kenter(FMT, ...) \
49 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
50 #define kleave(FMT, ...) \
51 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
52 #define kdebug(FMT, ...) \
53 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
58 unsigned long max_mapnr
;
59 unsigned long num_physpages
;
60 unsigned long highest_memmap_pfn
;
61 struct percpu_counter vm_committed_as
;
62 int sysctl_overcommit_memory
= OVERCOMMIT_GUESS
; /* heuristic overcommit */
63 int sysctl_overcommit_ratio
= 50; /* default is 50% */
64 int sysctl_max_map_count
= DEFAULT_MAX_MAP_COUNT
;
65 int sysctl_nr_trim_pages
= CONFIG_NOMMU_INITIAL_TRIM_EXCESS
;
66 unsigned long sysctl_user_reserve_kbytes __read_mostly
= 1UL << 17; /* 128MB */
67 unsigned long sysctl_admin_reserve_kbytes __read_mostly
= 1UL << 13; /* 8MB */
68 int heap_stack_gap
= 0;
70 atomic_long_t mmap_pages_allocated
;
73 * The global memory commitment made in the system can be a metric
74 * that can be used to drive ballooning decisions when Linux is hosted
75 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
76 * balancing memory across competing virtual machines that are hosted.
77 * Several metrics drive this policy engine including the guest reported
80 unsigned long vm_memory_committed(void)
82 return percpu_counter_read_positive(&vm_committed_as
);
85 EXPORT_SYMBOL_GPL(vm_memory_committed
);
87 EXPORT_SYMBOL(mem_map
);
88 EXPORT_SYMBOL(num_physpages
);
90 /* list of mapped, potentially shareable regions */
91 static struct kmem_cache
*vm_region_jar
;
92 struct rb_root nommu_region_tree
= RB_ROOT
;
93 DECLARE_RWSEM(nommu_region_sem
);
95 const struct vm_operations_struct generic_file_vm_ops
= {
99 * Return the total memory allocated for this pointer, not
100 * just what the caller asked for.
102 * Doesn't have to be accurate, i.e. may have races.
104 unsigned int kobjsize(const void *objp
)
109 * If the object we have should not have ksize performed on it,
112 if (!objp
|| !virt_addr_valid(objp
))
115 page
= virt_to_head_page(objp
);
118 * If the allocator sets PageSlab, we know the pointer came from
125 * If it's not a compound page, see if we have a matching VMA
126 * region. This test is intentionally done in reverse order,
127 * so if there's no VMA, we still fall through and hand back
128 * PAGE_SIZE for 0-order pages.
130 if (!PageCompound(page
)) {
131 struct vm_area_struct
*vma
;
133 vma
= find_vma(current
->mm
, (unsigned long)objp
);
135 return vma
->vm_end
- vma
->vm_start
;
139 * The ksize() function is only guaranteed to work for pointers
140 * returned by kmalloc(). So handle arbitrary pointers here.
142 return PAGE_SIZE
<< compound_order(page
);
145 long __get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
146 unsigned long start
, unsigned long nr_pages
,
147 unsigned int foll_flags
, struct page
**pages
,
148 struct vm_area_struct
**vmas
, int *nonblocking
)
150 struct vm_area_struct
*vma
;
151 unsigned long vm_flags
;
154 /* calculate required read or write permissions.
155 * If FOLL_FORCE is set, we only require the "MAY" flags.
157 vm_flags
= (foll_flags
& FOLL_WRITE
) ?
158 (VM_WRITE
| VM_MAYWRITE
) : (VM_READ
| VM_MAYREAD
);
159 vm_flags
&= (foll_flags
& FOLL_FORCE
) ?
160 (VM_MAYREAD
| VM_MAYWRITE
) : (VM_READ
| VM_WRITE
);
162 for (i
= 0; i
< nr_pages
; i
++) {
163 vma
= find_vma(mm
, start
);
165 goto finish_or_fault
;
167 /* protect what we can, including chardevs */
168 if ((vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)) ||
169 !(vm_flags
& vma
->vm_flags
))
170 goto finish_or_fault
;
173 pages
[i
] = virt_to_page(start
);
175 page_cache_get(pages
[i
]);
179 start
= (start
+ PAGE_SIZE
) & PAGE_MASK
;
185 return i
? : -EFAULT
;
189 * get a list of pages in an address range belonging to the specified process
190 * and indicate the VMA that covers each page
191 * - this is potentially dodgy as we may end incrementing the page count of a
192 * slab page or a secondary page from a compound page
193 * - don't permit access to VMAs that don't support it, such as I/O mappings
195 long get_user_pages(struct task_struct
*tsk
, struct mm_struct
*mm
,
196 unsigned long start
, unsigned long nr_pages
,
197 int write
, int force
, struct page
**pages
,
198 struct vm_area_struct
**vmas
)
207 return __get_user_pages(tsk
, mm
, start
, nr_pages
, flags
, pages
, vmas
,
210 EXPORT_SYMBOL(get_user_pages
);
213 * follow_pfn - look up PFN at a user virtual address
214 * @vma: memory mapping
215 * @address: user virtual address
216 * @pfn: location to store found PFN
218 * Only IO mappings and raw PFN mappings are allowed.
220 * Returns zero and the pfn at @pfn on success, -ve otherwise.
222 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
225 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
228 *pfn
= address
>> PAGE_SHIFT
;
231 EXPORT_SYMBOL(follow_pfn
);
233 LIST_HEAD(vmap_area_list
);
235 void vfree(const void *addr
)
239 EXPORT_SYMBOL(vfree
);
241 void *__vmalloc(unsigned long size
, gfp_t gfp_mask
, pgprot_t prot
)
244 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
245 * returns only a logical address.
247 return kmalloc(size
, (gfp_mask
| __GFP_COMP
) & ~__GFP_HIGHMEM
);
249 EXPORT_SYMBOL(__vmalloc
);
251 void *vmalloc_user(unsigned long size
)
255 ret
= __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
| __GFP_ZERO
,
258 struct vm_area_struct
*vma
;
260 down_write(¤t
->mm
->mmap_sem
);
261 vma
= find_vma(current
->mm
, (unsigned long)ret
);
263 vma
->vm_flags
|= VM_USERMAP
;
264 up_write(¤t
->mm
->mmap_sem
);
269 EXPORT_SYMBOL(vmalloc_user
);
271 struct page
*vmalloc_to_page(const void *addr
)
273 return virt_to_page(addr
);
275 EXPORT_SYMBOL(vmalloc_to_page
);
277 unsigned long vmalloc_to_pfn(const void *addr
)
279 return page_to_pfn(virt_to_page(addr
));
281 EXPORT_SYMBOL(vmalloc_to_pfn
);
283 long vread(char *buf
, char *addr
, unsigned long count
)
285 memcpy(buf
, addr
, count
);
289 long vwrite(char *buf
, char *addr
, unsigned long count
)
291 /* Don't allow overflow */
292 if ((unsigned long) addr
+ count
< count
)
293 count
= -(unsigned long) addr
;
295 memcpy(addr
, buf
, count
);
300 * vmalloc - allocate virtually continguos memory
302 * @size: allocation size
304 * Allocate enough pages to cover @size from the page level
305 * allocator and map them into continguos kernel virtual space.
307 * For tight control over page level allocator and protection flags
308 * use __vmalloc() instead.
310 void *vmalloc(unsigned long size
)
312 return __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
, PAGE_KERNEL
);
314 EXPORT_SYMBOL(vmalloc
);
317 * vzalloc - allocate virtually continguos memory with zero fill
319 * @size: allocation size
321 * Allocate enough pages to cover @size from the page level
322 * allocator and map them into continguos kernel virtual space.
323 * The memory allocated is set to zero.
325 * For tight control over page level allocator and protection flags
326 * use __vmalloc() instead.
328 void *vzalloc(unsigned long size
)
330 return __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
| __GFP_ZERO
,
333 EXPORT_SYMBOL(vzalloc
);
336 * vmalloc_node - allocate memory on a specific node
337 * @size: allocation size
340 * Allocate enough pages to cover @size from the page level
341 * allocator and map them into contiguous kernel virtual space.
343 * For tight control over page level allocator and protection flags
344 * use __vmalloc() instead.
346 void *vmalloc_node(unsigned long size
, int node
)
348 return vmalloc(size
);
350 EXPORT_SYMBOL(vmalloc_node
);
353 * vzalloc_node - allocate memory on a specific node with zero fill
354 * @size: allocation size
357 * Allocate enough pages to cover @size from the page level
358 * allocator and map them into contiguous kernel virtual space.
359 * The memory allocated is set to zero.
361 * For tight control over page level allocator and protection flags
362 * use __vmalloc() instead.
364 void *vzalloc_node(unsigned long size
, int node
)
366 return vzalloc(size
);
368 EXPORT_SYMBOL(vzalloc_node
);
370 #ifndef PAGE_KERNEL_EXEC
371 # define PAGE_KERNEL_EXEC PAGE_KERNEL
375 * vmalloc_exec - allocate virtually contiguous, executable memory
376 * @size: allocation size
378 * Kernel-internal function to allocate enough pages to cover @size
379 * the page level allocator and map them into contiguous and
380 * executable kernel virtual space.
382 * For tight control over page level allocator and protection flags
383 * use __vmalloc() instead.
386 void *vmalloc_exec(unsigned long size
)
388 return __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
, PAGE_KERNEL_EXEC
);
392 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
393 * @size: allocation size
395 * Allocate enough 32bit PA addressable pages to cover @size from the
396 * page level allocator and map them into continguos kernel virtual space.
398 void *vmalloc_32(unsigned long size
)
400 return __vmalloc(size
, GFP_KERNEL
, PAGE_KERNEL
);
402 EXPORT_SYMBOL(vmalloc_32
);
405 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
406 * @size: allocation size
408 * The resulting memory area is 32bit addressable and zeroed so it can be
409 * mapped to userspace without leaking data.
411 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
412 * remap_vmalloc_range() are permissible.
414 void *vmalloc_32_user(unsigned long size
)
417 * We'll have to sort out the ZONE_DMA bits for 64-bit,
418 * but for now this can simply use vmalloc_user() directly.
420 return vmalloc_user(size
);
422 EXPORT_SYMBOL(vmalloc_32_user
);
424 void *vmap(struct page
**pages
, unsigned int count
, unsigned long flags
, pgprot_t prot
)
431 void vunmap(const void *addr
)
435 EXPORT_SYMBOL(vunmap
);
437 void *vm_map_ram(struct page
**pages
, unsigned int count
, int node
, pgprot_t prot
)
442 EXPORT_SYMBOL(vm_map_ram
);
444 void vm_unmap_ram(const void *mem
, unsigned int count
)
448 EXPORT_SYMBOL(vm_unmap_ram
);
450 void vm_unmap_aliases(void)
453 EXPORT_SYMBOL_GPL(vm_unmap_aliases
);
456 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
459 void __attribute__((weak
)) vmalloc_sync_all(void)
464 * alloc_vm_area - allocate a range of kernel address space
465 * @size: size of the area
467 * Returns: NULL on failure, vm_struct on success
469 * This function reserves a range of kernel address space, and
470 * allocates pagetables to map that range. No actual mappings
471 * are created. If the kernel address space is not shared
472 * between processes, it syncs the pagetable across all
475 struct vm_struct
*alloc_vm_area(size_t size
, pte_t
**ptes
)
480 EXPORT_SYMBOL_GPL(alloc_vm_area
);
482 void free_vm_area(struct vm_struct
*area
)
486 EXPORT_SYMBOL_GPL(free_vm_area
);
488 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
493 EXPORT_SYMBOL(vm_insert_page
);
496 * sys_brk() for the most part doesn't need the global kernel
497 * lock, except when an application is doing something nasty
498 * like trying to un-brk an area that has already been mapped
499 * to a regular file. in this case, the unmapping will need
500 * to invoke file system routines that need the global lock.
502 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
504 struct mm_struct
*mm
= current
->mm
;
506 if (brk
< mm
->start_brk
|| brk
> mm
->context
.end_brk
)
513 * Always allow shrinking brk
515 if (brk
<= mm
->brk
) {
521 * Ok, looks good - let it rip.
523 flush_icache_range(mm
->brk
, brk
);
524 return mm
->brk
= brk
;
528 * initialise the VMA and region record slabs
530 void __init
mmap_init(void)
534 ret
= percpu_counter_init(&vm_committed_as
, 0);
536 vm_region_jar
= KMEM_CACHE(vm_region
, SLAB_PANIC
);
540 * validate the region tree
541 * - the caller must hold the region lock
543 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
544 static noinline
void validate_nommu_regions(void)
546 struct vm_region
*region
, *last
;
547 struct rb_node
*p
, *lastp
;
549 lastp
= rb_first(&nommu_region_tree
);
553 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
554 BUG_ON(unlikely(last
->vm_end
<= last
->vm_start
));
555 BUG_ON(unlikely(last
->vm_top
< last
->vm_end
));
557 while ((p
= rb_next(lastp
))) {
558 region
= rb_entry(p
, struct vm_region
, vm_rb
);
559 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
561 BUG_ON(unlikely(region
->vm_end
<= region
->vm_start
));
562 BUG_ON(unlikely(region
->vm_top
< region
->vm_end
));
563 BUG_ON(unlikely(region
->vm_start
< last
->vm_top
));
569 static void validate_nommu_regions(void)
575 * add a region into the global tree
577 static void add_nommu_region(struct vm_region
*region
)
579 struct vm_region
*pregion
;
580 struct rb_node
**p
, *parent
;
582 validate_nommu_regions();
585 p
= &nommu_region_tree
.rb_node
;
588 pregion
= rb_entry(parent
, struct vm_region
, vm_rb
);
589 if (region
->vm_start
< pregion
->vm_start
)
591 else if (region
->vm_start
> pregion
->vm_start
)
593 else if (pregion
== region
)
599 rb_link_node(®ion
->vm_rb
, parent
, p
);
600 rb_insert_color(®ion
->vm_rb
, &nommu_region_tree
);
602 validate_nommu_regions();
606 * delete a region from the global tree
608 static void delete_nommu_region(struct vm_region
*region
)
610 BUG_ON(!nommu_region_tree
.rb_node
);
612 validate_nommu_regions();
613 rb_erase(®ion
->vm_rb
, &nommu_region_tree
);
614 validate_nommu_regions();
618 * free a contiguous series of pages
620 static void free_page_series(unsigned long from
, unsigned long to
)
622 for (; from
< to
; from
+= PAGE_SIZE
) {
623 struct page
*page
= virt_to_page(from
);
625 kdebug("- free %lx", from
);
626 atomic_long_dec(&mmap_pages_allocated
);
627 if (page_count(page
) != 1)
628 kdebug("free page %p: refcount not one: %d",
629 page
, page_count(page
));
635 * release a reference to a region
636 * - the caller must hold the region semaphore for writing, which this releases
637 * - the region may not have been added to the tree yet, in which case vm_top
638 * will equal vm_start
640 static void __put_nommu_region(struct vm_region
*region
)
641 __releases(nommu_region_sem
)
643 kenter("%p{%d}", region
, region
->vm_usage
);
645 BUG_ON(!nommu_region_tree
.rb_node
);
647 if (--region
->vm_usage
== 0) {
648 if (region
->vm_top
> region
->vm_start
)
649 delete_nommu_region(region
);
650 up_write(&nommu_region_sem
);
653 fput(region
->vm_file
);
655 /* IO memory and memory shared directly out of the pagecache
656 * from ramfs/tmpfs mustn't be released here */
657 if (region
->vm_flags
& VM_MAPPED_COPY
) {
658 kdebug("free series");
659 free_page_series(region
->vm_start
, region
->vm_top
);
661 kmem_cache_free(vm_region_jar
, region
);
663 up_write(&nommu_region_sem
);
668 * release a reference to a region
670 static void put_nommu_region(struct vm_region
*region
)
672 down_write(&nommu_region_sem
);
673 __put_nommu_region(region
);
677 * update protection on a vma
679 static void protect_vma(struct vm_area_struct
*vma
, unsigned long flags
)
682 struct mm_struct
*mm
= vma
->vm_mm
;
683 long start
= vma
->vm_start
& PAGE_MASK
;
684 while (start
< vma
->vm_end
) {
685 protect_page(mm
, start
, flags
);
688 update_protections(mm
);
693 * add a VMA into a process's mm_struct in the appropriate place in the list
694 * and tree and add to the address space's page tree also if not an anonymous
696 * - should be called with mm->mmap_sem held writelocked
698 static void add_vma_to_mm(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
700 struct vm_area_struct
*pvma
, *prev
;
701 struct address_space
*mapping
;
702 struct rb_node
**p
, *parent
, *rb_prev
;
706 BUG_ON(!vma
->vm_region
);
711 protect_vma(vma
, vma
->vm_flags
);
713 /* add the VMA to the mapping */
715 mapping
= vma
->vm_file
->f_mapping
;
717 mutex_lock(&mapping
->i_mmap_mutex
);
718 flush_dcache_mmap_lock(mapping
);
719 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
720 flush_dcache_mmap_unlock(mapping
);
721 mutex_unlock(&mapping
->i_mmap_mutex
);
724 /* add the VMA to the tree */
725 parent
= rb_prev
= NULL
;
726 p
= &mm
->mm_rb
.rb_node
;
729 pvma
= rb_entry(parent
, struct vm_area_struct
, vm_rb
);
731 /* sort by: start addr, end addr, VMA struct addr in that order
732 * (the latter is necessary as we may get identical VMAs) */
733 if (vma
->vm_start
< pvma
->vm_start
)
735 else if (vma
->vm_start
> pvma
->vm_start
) {
738 } else if (vma
->vm_end
< pvma
->vm_end
)
740 else if (vma
->vm_end
> pvma
->vm_end
) {
743 } else if (vma
< pvma
)
745 else if (vma
> pvma
) {
752 rb_link_node(&vma
->vm_rb
, parent
, p
);
753 rb_insert_color(&vma
->vm_rb
, &mm
->mm_rb
);
755 /* add VMA to the VMA list also */
758 prev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
760 __vma_link_list(mm
, vma
, prev
, parent
);
764 * delete a VMA from its owning mm_struct and address space
766 static void delete_vma_from_mm(struct vm_area_struct
*vma
)
768 struct address_space
*mapping
;
769 struct mm_struct
*mm
= vma
->vm_mm
;
776 if (mm
->mmap_cache
== vma
)
777 mm
->mmap_cache
= NULL
;
779 /* remove the VMA from the mapping */
781 mapping
= vma
->vm_file
->f_mapping
;
783 mutex_lock(&mapping
->i_mmap_mutex
);
784 flush_dcache_mmap_lock(mapping
);
785 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
786 flush_dcache_mmap_unlock(mapping
);
787 mutex_unlock(&mapping
->i_mmap_mutex
);
790 /* remove from the MM's tree and list */
791 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
794 vma
->vm_prev
->vm_next
= vma
->vm_next
;
796 mm
->mmap
= vma
->vm_next
;
799 vma
->vm_next
->vm_prev
= vma
->vm_prev
;
803 * destroy a VMA record
805 static void delete_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
808 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
809 vma
->vm_ops
->close(vma
);
812 put_nommu_region(vma
->vm_region
);
813 kmem_cache_free(vm_area_cachep
, vma
);
817 * look up the first VMA in which addr resides, NULL if none
818 * - should be called with mm->mmap_sem at least held readlocked
820 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
822 struct vm_area_struct
*vma
;
824 /* check the cache first */
825 vma
= ACCESS_ONCE(mm
->mmap_cache
);
826 if (vma
&& vma
->vm_start
<= addr
&& vma
->vm_end
> addr
)
829 /* trawl the list (there may be multiple mappings in which addr
831 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
832 if (vma
->vm_start
> addr
)
834 if (vma
->vm_end
> addr
) {
835 mm
->mmap_cache
= vma
;
842 EXPORT_SYMBOL(find_vma
);
846 * - we don't extend stack VMAs under NOMMU conditions
848 struct vm_area_struct
*find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
850 return find_vma(mm
, addr
);
854 * expand a stack to a given address
855 * - not supported under NOMMU conditions
857 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
863 * look up the first VMA exactly that exactly matches addr
864 * - should be called with mm->mmap_sem at least held readlocked
866 static struct vm_area_struct
*find_vma_exact(struct mm_struct
*mm
,
870 struct vm_area_struct
*vma
;
871 unsigned long end
= addr
+ len
;
873 /* check the cache first */
874 vma
= mm
->mmap_cache
;
875 if (vma
&& vma
->vm_start
== addr
&& vma
->vm_end
== end
)
878 /* trawl the list (there may be multiple mappings in which addr
880 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
881 if (vma
->vm_start
< addr
)
883 if (vma
->vm_start
> addr
)
885 if (vma
->vm_end
== end
) {
886 mm
->mmap_cache
= vma
;
895 * determine whether a mapping should be permitted and, if so, what sort of
896 * mapping we're capable of supporting
898 static int validate_mmap_request(struct file
*file
,
904 unsigned long *_capabilities
)
906 unsigned long capabilities
, rlen
;
909 /* do the simple checks first */
910 if (flags
& MAP_FIXED
) {
912 "%d: Can't do fixed-address/overlay mmap of RAM\n",
917 if ((flags
& MAP_TYPE
) != MAP_PRIVATE
&&
918 (flags
& MAP_TYPE
) != MAP_SHARED
)
924 /* Careful about overflows.. */
925 rlen
= PAGE_ALIGN(len
);
926 if (!rlen
|| rlen
> TASK_SIZE
)
929 /* offset overflow? */
930 if ((pgoff
+ (rlen
>> PAGE_SHIFT
)) < pgoff
)
934 /* validate file mapping requests */
935 struct address_space
*mapping
;
937 /* files must support mmap */
938 if (!file
->f_op
|| !file
->f_op
->mmap
)
941 /* work out if what we've got could possibly be shared
942 * - we support chardevs that provide their own "memory"
943 * - we support files/blockdevs that are memory backed
945 mapping
= file
->f_mapping
;
947 mapping
= file_inode(file
)->i_mapping
;
950 if (mapping
&& mapping
->backing_dev_info
)
951 capabilities
= mapping
->backing_dev_info
->capabilities
;
954 /* no explicit capabilities set, so assume some
956 switch (file_inode(file
)->i_mode
& S_IFMT
) {
959 capabilities
= BDI_CAP_MAP_COPY
;
974 /* eliminate any capabilities that we can't support on this
976 if (!file
->f_op
->get_unmapped_area
)
977 capabilities
&= ~BDI_CAP_MAP_DIRECT
;
978 if (!file
->f_op
->read
)
979 capabilities
&= ~BDI_CAP_MAP_COPY
;
981 /* The file shall have been opened with read permission. */
982 if (!(file
->f_mode
& FMODE_READ
))
985 if (flags
& MAP_SHARED
) {
986 /* do checks for writing, appending and locking */
987 if ((prot
& PROT_WRITE
) &&
988 !(file
->f_mode
& FMODE_WRITE
))
991 if (IS_APPEND(file_inode(file
)) &&
992 (file
->f_mode
& FMODE_WRITE
))
995 if (locks_verify_locked(file_inode(file
)))
998 if (!(capabilities
& BDI_CAP_MAP_DIRECT
))
1001 /* we mustn't privatise shared mappings */
1002 capabilities
&= ~BDI_CAP_MAP_COPY
;
1005 /* we're going to read the file into private memory we
1007 if (!(capabilities
& BDI_CAP_MAP_COPY
))
1010 /* we don't permit a private writable mapping to be
1011 * shared with the backing device */
1012 if (prot
& PROT_WRITE
)
1013 capabilities
&= ~BDI_CAP_MAP_DIRECT
;
1016 if (capabilities
& BDI_CAP_MAP_DIRECT
) {
1017 if (((prot
& PROT_READ
) && !(capabilities
& BDI_CAP_READ_MAP
)) ||
1018 ((prot
& PROT_WRITE
) && !(capabilities
& BDI_CAP_WRITE_MAP
)) ||
1019 ((prot
& PROT_EXEC
) && !(capabilities
& BDI_CAP_EXEC_MAP
))
1021 capabilities
&= ~BDI_CAP_MAP_DIRECT
;
1022 if (flags
& MAP_SHARED
) {
1024 "MAP_SHARED not completely supported on !MMU\n");
1030 /* handle executable mappings and implied executable
1032 if (file
->f_path
.mnt
->mnt_flags
& MNT_NOEXEC
) {
1033 if (prot
& PROT_EXEC
)
1036 else if ((prot
& PROT_READ
) && !(prot
& PROT_EXEC
)) {
1037 /* handle implication of PROT_EXEC by PROT_READ */
1038 if (current
->personality
& READ_IMPLIES_EXEC
) {
1039 if (capabilities
& BDI_CAP_EXEC_MAP
)
1043 else if ((prot
& PROT_READ
) &&
1044 (prot
& PROT_EXEC
) &&
1045 !(capabilities
& BDI_CAP_EXEC_MAP
)
1047 /* backing file is not executable, try to copy */
1048 capabilities
&= ~BDI_CAP_MAP_DIRECT
;
1052 /* anonymous mappings are always memory backed and can be
1055 capabilities
= BDI_CAP_MAP_COPY
;
1057 /* handle PROT_EXEC implication by PROT_READ */
1058 if ((prot
& PROT_READ
) &&
1059 (current
->personality
& READ_IMPLIES_EXEC
))
1063 /* allow the security API to have its say */
1064 ret
= security_mmap_addr(addr
);
1069 *_capabilities
= capabilities
;
1074 * we've determined that we can make the mapping, now translate what we
1075 * now know into VMA flags
1077 static unsigned long determine_vm_flags(struct file
*file
,
1079 unsigned long flags
,
1080 unsigned long capabilities
)
1082 unsigned long vm_flags
;
1084 vm_flags
= calc_vm_prot_bits(prot
) | calc_vm_flag_bits(flags
);
1085 /* vm_flags |= mm->def_flags; */
1087 if (!(capabilities
& BDI_CAP_MAP_DIRECT
)) {
1088 /* attempt to share read-only copies of mapped file chunks */
1089 vm_flags
|= VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
1090 if (file
&& !(prot
& PROT_WRITE
))
1091 vm_flags
|= VM_MAYSHARE
;
1093 /* overlay a shareable mapping on the backing device or inode
1094 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1096 vm_flags
|= VM_MAYSHARE
| (capabilities
& BDI_CAP_VMFLAGS
);
1097 if (flags
& MAP_SHARED
)
1098 vm_flags
|= VM_SHARED
;
1101 /* refuse to let anyone share private mappings with this process if
1102 * it's being traced - otherwise breakpoints set in it may interfere
1103 * with another untraced process
1105 if ((flags
& MAP_PRIVATE
) && current
->ptrace
)
1106 vm_flags
&= ~VM_MAYSHARE
;
1112 * set up a shared mapping on a file (the driver or filesystem provides and
1115 static int do_mmap_shared_file(struct vm_area_struct
*vma
)
1119 ret
= vma
->vm_file
->f_op
->mmap(vma
->vm_file
, vma
);
1121 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
1127 /* getting -ENOSYS indicates that direct mmap isn't possible (as
1128 * opposed to tried but failed) so we can only give a suitable error as
1129 * it's not possible to make a private copy if MAP_SHARED was given */
1134 * set up a private mapping or an anonymous shared mapping
1136 static int do_mmap_private(struct vm_area_struct
*vma
,
1137 struct vm_region
*region
,
1139 unsigned long capabilities
)
1142 unsigned long total
, point
, n
;
1146 /* invoke the file's mapping function so that it can keep track of
1147 * shared mappings on devices or memory
1148 * - VM_MAYSHARE will be set if it may attempt to share
1150 if (capabilities
& BDI_CAP_MAP_DIRECT
) {
1151 ret
= vma
->vm_file
->f_op
->mmap(vma
->vm_file
, vma
);
1153 /* shouldn't return success if we're not sharing */
1154 BUG_ON(!(vma
->vm_flags
& VM_MAYSHARE
));
1155 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
1161 /* getting an ENOSYS error indicates that direct mmap isn't
1162 * possible (as opposed to tried but failed) so we'll try to
1163 * make a private copy of the data and map that instead */
1167 /* allocate some memory to hold the mapping
1168 * - note that this may not return a page-aligned address if the object
1169 * we're allocating is smaller than a page
1171 order
= get_order(len
);
1172 kdebug("alloc order %d for %lx", order
, len
);
1174 pages
= alloc_pages(GFP_KERNEL
, order
);
1179 atomic_long_add(total
, &mmap_pages_allocated
);
1181 point
= len
>> PAGE_SHIFT
;
1183 /* we allocated a power-of-2 sized page set, so we may want to trim off
1185 if (sysctl_nr_trim_pages
&& total
- point
>= sysctl_nr_trim_pages
) {
1186 while (total
> point
) {
1187 order
= ilog2(total
- point
);
1189 kdebug("shave %lu/%lu @%lu", n
, total
- point
, total
);
1190 atomic_long_sub(n
, &mmap_pages_allocated
);
1192 set_page_refcounted(pages
+ total
);
1193 __free_pages(pages
+ total
, order
);
1197 for (point
= 1; point
< total
; point
++)
1198 set_page_refcounted(&pages
[point
]);
1200 base
= page_address(pages
);
1201 region
->vm_flags
= vma
->vm_flags
|= VM_MAPPED_COPY
;
1202 region
->vm_start
= (unsigned long) base
;
1203 region
->vm_end
= region
->vm_start
+ len
;
1204 region
->vm_top
= region
->vm_start
+ (total
<< PAGE_SHIFT
);
1206 vma
->vm_start
= region
->vm_start
;
1207 vma
->vm_end
= region
->vm_start
+ len
;
1210 /* read the contents of a file into the copy */
1211 mm_segment_t old_fs
;
1214 fpos
= vma
->vm_pgoff
;
1215 fpos
<<= PAGE_SHIFT
;
1219 ret
= vma
->vm_file
->f_op
->read(vma
->vm_file
, base
, len
, &fpos
);
1225 /* clear the last little bit */
1227 memset(base
+ ret
, 0, len
- ret
);
1234 free_page_series(region
->vm_start
, region
->vm_top
);
1235 region
->vm_start
= vma
->vm_start
= 0;
1236 region
->vm_end
= vma
->vm_end
= 0;
1241 printk("Allocation of length %lu from process %d (%s) failed\n",
1242 len
, current
->pid
, current
->comm
);
1248 * handle mapping creation for uClinux
1250 unsigned long do_mmap_pgoff(struct file
*file
,
1254 unsigned long flags
,
1255 unsigned long pgoff
,
1256 unsigned long *populate
)
1258 struct vm_area_struct
*vma
;
1259 struct vm_region
*region
;
1261 unsigned long capabilities
, vm_flags
, result
;
1264 kenter(",%lx,%lx,%lx,%lx,%lx", addr
, len
, prot
, flags
, pgoff
);
1268 /* decide whether we should attempt the mapping, and if so what sort of
1270 ret
= validate_mmap_request(file
, addr
, len
, prot
, flags
, pgoff
,
1273 kleave(" = %d [val]", ret
);
1277 /* we ignore the address hint */
1279 len
= PAGE_ALIGN(len
);
1281 /* we've determined that we can make the mapping, now translate what we
1282 * now know into VMA flags */
1283 vm_flags
= determine_vm_flags(file
, prot
, flags
, capabilities
);
1285 /* we're going to need to record the mapping */
1286 region
= kmem_cache_zalloc(vm_region_jar
, GFP_KERNEL
);
1288 goto error_getting_region
;
1290 vma
= kmem_cache_zalloc(vm_area_cachep
, GFP_KERNEL
);
1292 goto error_getting_vma
;
1294 region
->vm_usage
= 1;
1295 region
->vm_flags
= vm_flags
;
1296 region
->vm_pgoff
= pgoff
;
1298 INIT_LIST_HEAD(&vma
->anon_vma_chain
);
1299 vma
->vm_flags
= vm_flags
;
1300 vma
->vm_pgoff
= pgoff
;
1303 region
->vm_file
= get_file(file
);
1304 vma
->vm_file
= get_file(file
);
1307 down_write(&nommu_region_sem
);
1309 /* if we want to share, we need to check for regions created by other
1310 * mmap() calls that overlap with our proposed mapping
1311 * - we can only share with a superset match on most regular files
1312 * - shared mappings on character devices and memory backed files are
1313 * permitted to overlap inexactly as far as we are concerned for in
1314 * these cases, sharing is handled in the driver or filesystem rather
1317 if (vm_flags
& VM_MAYSHARE
) {
1318 struct vm_region
*pregion
;
1319 unsigned long pglen
, rpglen
, pgend
, rpgend
, start
;
1321 pglen
= (len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1322 pgend
= pgoff
+ pglen
;
1324 for (rb
= rb_first(&nommu_region_tree
); rb
; rb
= rb_next(rb
)) {
1325 pregion
= rb_entry(rb
, struct vm_region
, vm_rb
);
1327 if (!(pregion
->vm_flags
& VM_MAYSHARE
))
1330 /* search for overlapping mappings on the same file */
1331 if (file_inode(pregion
->vm_file
) !=
1335 if (pregion
->vm_pgoff
>= pgend
)
1338 rpglen
= pregion
->vm_end
- pregion
->vm_start
;
1339 rpglen
= (rpglen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1340 rpgend
= pregion
->vm_pgoff
+ rpglen
;
1341 if (pgoff
>= rpgend
)
1344 /* handle inexactly overlapping matches between
1346 if ((pregion
->vm_pgoff
!= pgoff
|| rpglen
!= pglen
) &&
1347 !(pgoff
>= pregion
->vm_pgoff
&& pgend
<= rpgend
)) {
1348 /* new mapping is not a subset of the region */
1349 if (!(capabilities
& BDI_CAP_MAP_DIRECT
))
1350 goto sharing_violation
;
1354 /* we've found a region we can share */
1355 pregion
->vm_usage
++;
1356 vma
->vm_region
= pregion
;
1357 start
= pregion
->vm_start
;
1358 start
+= (pgoff
- pregion
->vm_pgoff
) << PAGE_SHIFT
;
1359 vma
->vm_start
= start
;
1360 vma
->vm_end
= start
+ len
;
1362 if (pregion
->vm_flags
& VM_MAPPED_COPY
) {
1363 kdebug("share copy");
1364 vma
->vm_flags
|= VM_MAPPED_COPY
;
1366 kdebug("share mmap");
1367 ret
= do_mmap_shared_file(vma
);
1369 vma
->vm_region
= NULL
;
1372 pregion
->vm_usage
--;
1374 goto error_just_free
;
1377 fput(region
->vm_file
);
1378 kmem_cache_free(vm_region_jar
, region
);
1384 /* obtain the address at which to make a shared mapping
1385 * - this is the hook for quasi-memory character devices to
1386 * tell us the location of a shared mapping
1388 if (capabilities
& BDI_CAP_MAP_DIRECT
) {
1389 addr
= file
->f_op
->get_unmapped_area(file
, addr
, len
,
1391 if (IS_ERR_VALUE(addr
)) {
1394 goto error_just_free
;
1396 /* the driver refused to tell us where to site
1397 * the mapping so we'll have to attempt to copy
1400 if (!(capabilities
& BDI_CAP_MAP_COPY
))
1401 goto error_just_free
;
1403 capabilities
&= ~BDI_CAP_MAP_DIRECT
;
1405 vma
->vm_start
= region
->vm_start
= addr
;
1406 vma
->vm_end
= region
->vm_end
= addr
+ len
;
1411 vma
->vm_region
= region
;
1413 /* set up the mapping
1414 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1416 if (file
&& vma
->vm_flags
& VM_SHARED
)
1417 ret
= do_mmap_shared_file(vma
);
1419 ret
= do_mmap_private(vma
, region
, len
, capabilities
);
1421 goto error_just_free
;
1422 add_nommu_region(region
);
1424 /* clear anonymous mappings that don't ask for uninitialized data */
1425 if (!vma
->vm_file
&& !(flags
& MAP_UNINITIALIZED
))
1426 memset((void *)region
->vm_start
, 0,
1427 region
->vm_end
- region
->vm_start
);
1429 /* okay... we have a mapping; now we have to register it */
1430 result
= vma
->vm_start
;
1432 current
->mm
->total_vm
+= len
>> PAGE_SHIFT
;
1435 add_vma_to_mm(current
->mm
, vma
);
1437 /* we flush the region from the icache only when the first executable
1438 * mapping of it is made */
1439 if (vma
->vm_flags
& VM_EXEC
&& !region
->vm_icache_flushed
) {
1440 flush_icache_range(region
->vm_start
, region
->vm_end
);
1441 region
->vm_icache_flushed
= true;
1444 up_write(&nommu_region_sem
);
1446 kleave(" = %lx", result
);
1450 up_write(&nommu_region_sem
);
1452 if (region
->vm_file
)
1453 fput(region
->vm_file
);
1454 kmem_cache_free(vm_region_jar
, region
);
1457 kmem_cache_free(vm_area_cachep
, vma
);
1458 kleave(" = %d", ret
);
1462 up_write(&nommu_region_sem
);
1463 printk(KERN_WARNING
"Attempt to share mismatched mappings\n");
1468 kmem_cache_free(vm_region_jar
, region
);
1469 printk(KERN_WARNING
"Allocation of vma for %lu byte allocation"
1470 " from process %d failed\n",
1475 error_getting_region
:
1476 printk(KERN_WARNING
"Allocation of vm region for %lu byte allocation"
1477 " from process %d failed\n",
1483 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1484 unsigned long, prot
, unsigned long, flags
,
1485 unsigned long, fd
, unsigned long, pgoff
)
1487 struct file
*file
= NULL
;
1488 unsigned long retval
= -EBADF
;
1490 audit_mmap_fd(fd
, flags
);
1491 if (!(flags
& MAP_ANONYMOUS
)) {
1497 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1499 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1507 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1508 struct mmap_arg_struct
{
1512 unsigned long flags
;
1514 unsigned long offset
;
1517 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1519 struct mmap_arg_struct a
;
1521 if (copy_from_user(&a
, arg
, sizeof(a
)))
1523 if (a
.offset
& ~PAGE_MASK
)
1526 return sys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1527 a
.offset
>> PAGE_SHIFT
);
1529 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1532 * split a vma into two pieces at address 'addr', a new vma is allocated either
1533 * for the first part or the tail.
1535 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1536 unsigned long addr
, int new_below
)
1538 struct vm_area_struct
*new;
1539 struct vm_region
*region
;
1540 unsigned long npages
;
1544 /* we're only permitted to split anonymous regions (these should have
1545 * only a single usage on the region) */
1549 if (mm
->map_count
>= sysctl_max_map_count
)
1552 region
= kmem_cache_alloc(vm_region_jar
, GFP_KERNEL
);
1556 new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
1558 kmem_cache_free(vm_region_jar
, region
);
1562 /* most fields are the same, copy all, and then fixup */
1564 *region
= *vma
->vm_region
;
1565 new->vm_region
= region
;
1567 npages
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
1570 region
->vm_top
= region
->vm_end
= new->vm_end
= addr
;
1572 region
->vm_start
= new->vm_start
= addr
;
1573 region
->vm_pgoff
= new->vm_pgoff
+= npages
;
1576 if (new->vm_ops
&& new->vm_ops
->open
)
1577 new->vm_ops
->open(new);
1579 delete_vma_from_mm(vma
);
1580 down_write(&nommu_region_sem
);
1581 delete_nommu_region(vma
->vm_region
);
1583 vma
->vm_region
->vm_start
= vma
->vm_start
= addr
;
1584 vma
->vm_region
->vm_pgoff
= vma
->vm_pgoff
+= npages
;
1586 vma
->vm_region
->vm_end
= vma
->vm_end
= addr
;
1587 vma
->vm_region
->vm_top
= addr
;
1589 add_nommu_region(vma
->vm_region
);
1590 add_nommu_region(new->vm_region
);
1591 up_write(&nommu_region_sem
);
1592 add_vma_to_mm(mm
, vma
);
1593 add_vma_to_mm(mm
, new);
1598 * shrink a VMA by removing the specified chunk from either the beginning or
1601 static int shrink_vma(struct mm_struct
*mm
,
1602 struct vm_area_struct
*vma
,
1603 unsigned long from
, unsigned long to
)
1605 struct vm_region
*region
;
1609 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1611 delete_vma_from_mm(vma
);
1612 if (from
> vma
->vm_start
)
1616 add_vma_to_mm(mm
, vma
);
1618 /* cut the backing region down to size */
1619 region
= vma
->vm_region
;
1620 BUG_ON(region
->vm_usage
!= 1);
1622 down_write(&nommu_region_sem
);
1623 delete_nommu_region(region
);
1624 if (from
> region
->vm_start
) {
1625 to
= region
->vm_top
;
1626 region
->vm_top
= region
->vm_end
= from
;
1628 region
->vm_start
= to
;
1630 add_nommu_region(region
);
1631 up_write(&nommu_region_sem
);
1633 free_page_series(from
, to
);
1639 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1640 * VMA, though it need not cover the whole VMA
1642 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
)
1644 struct vm_area_struct
*vma
;
1648 kenter(",%lx,%zx", start
, len
);
1650 len
= PAGE_ALIGN(len
);
1656 /* find the first potentially overlapping VMA */
1657 vma
= find_vma(mm
, start
);
1659 static int limit
= 0;
1662 "munmap of memory not mmapped by process %d"
1663 " (%s): 0x%lx-0x%lx\n",
1664 current
->pid
, current
->comm
,
1665 start
, start
+ len
- 1);
1671 /* we're allowed to split an anonymous VMA but not a file-backed one */
1674 if (start
> vma
->vm_start
) {
1675 kleave(" = -EINVAL [miss]");
1678 if (end
== vma
->vm_end
)
1679 goto erase_whole_vma
;
1682 kleave(" = -EINVAL [split file]");
1685 /* the chunk must be a subset of the VMA found */
1686 if (start
== vma
->vm_start
&& end
== vma
->vm_end
)
1687 goto erase_whole_vma
;
1688 if (start
< vma
->vm_start
|| end
> vma
->vm_end
) {
1689 kleave(" = -EINVAL [superset]");
1692 if (start
& ~PAGE_MASK
) {
1693 kleave(" = -EINVAL [unaligned start]");
1696 if (end
!= vma
->vm_end
&& end
& ~PAGE_MASK
) {
1697 kleave(" = -EINVAL [unaligned split]");
1700 if (start
!= vma
->vm_start
&& end
!= vma
->vm_end
) {
1701 ret
= split_vma(mm
, vma
, start
, 1);
1703 kleave(" = %d [split]", ret
);
1707 return shrink_vma(mm
, vma
, start
, end
);
1711 delete_vma_from_mm(vma
);
1712 delete_vma(mm
, vma
);
1716 EXPORT_SYMBOL(do_munmap
);
1718 int vm_munmap(unsigned long addr
, size_t len
)
1720 struct mm_struct
*mm
= current
->mm
;
1723 down_write(&mm
->mmap_sem
);
1724 ret
= do_munmap(mm
, addr
, len
);
1725 up_write(&mm
->mmap_sem
);
1728 EXPORT_SYMBOL(vm_munmap
);
1730 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
1732 return vm_munmap(addr
, len
);
1736 * release all the mappings made in a process's VM space
1738 void exit_mmap(struct mm_struct
*mm
)
1740 struct vm_area_struct
*vma
;
1749 while ((vma
= mm
->mmap
)) {
1750 mm
->mmap
= vma
->vm_next
;
1751 delete_vma_from_mm(vma
);
1752 delete_vma(mm
, vma
);
1759 unsigned long vm_brk(unsigned long addr
, unsigned long len
)
1765 * expand (or shrink) an existing mapping, potentially moving it at the same
1766 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1768 * under NOMMU conditions, we only permit changing a mapping's size, and only
1769 * as long as it stays within the region allocated by do_mmap_private() and the
1770 * block is not shareable
1772 * MREMAP_FIXED is not supported under NOMMU conditions
1774 static unsigned long do_mremap(unsigned long addr
,
1775 unsigned long old_len
, unsigned long new_len
,
1776 unsigned long flags
, unsigned long new_addr
)
1778 struct vm_area_struct
*vma
;
1780 /* insanity checks first */
1781 old_len
= PAGE_ALIGN(old_len
);
1782 new_len
= PAGE_ALIGN(new_len
);
1783 if (old_len
== 0 || new_len
== 0)
1784 return (unsigned long) -EINVAL
;
1786 if (addr
& ~PAGE_MASK
)
1789 if (flags
& MREMAP_FIXED
&& new_addr
!= addr
)
1790 return (unsigned long) -EINVAL
;
1792 vma
= find_vma_exact(current
->mm
, addr
, old_len
);
1794 return (unsigned long) -EINVAL
;
1796 if (vma
->vm_end
!= vma
->vm_start
+ old_len
)
1797 return (unsigned long) -EFAULT
;
1799 if (vma
->vm_flags
& VM_MAYSHARE
)
1800 return (unsigned long) -EPERM
;
1802 if (new_len
> vma
->vm_region
->vm_end
- vma
->vm_region
->vm_start
)
1803 return (unsigned long) -ENOMEM
;
1805 /* all checks complete - do it */
1806 vma
->vm_end
= vma
->vm_start
+ new_len
;
1807 return vma
->vm_start
;
1810 SYSCALL_DEFINE5(mremap
, unsigned long, addr
, unsigned long, old_len
,
1811 unsigned long, new_len
, unsigned long, flags
,
1812 unsigned long, new_addr
)
1816 down_write(¤t
->mm
->mmap_sem
);
1817 ret
= do_mremap(addr
, old_len
, new_len
, flags
, new_addr
);
1818 up_write(¤t
->mm
->mmap_sem
);
1822 struct page
*follow_page_mask(struct vm_area_struct
*vma
,
1823 unsigned long address
, unsigned int flags
,
1824 unsigned int *page_mask
)
1830 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1831 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1833 if (addr
!= (pfn
<< PAGE_SHIFT
))
1836 vma
->vm_flags
|= VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
;
1839 EXPORT_SYMBOL(remap_pfn_range
);
1841 int vm_iomap_memory(struct vm_area_struct
*vma
, phys_addr_t start
, unsigned long len
)
1843 unsigned long pfn
= start
>> PAGE_SHIFT
;
1844 unsigned long vm_len
= vma
->vm_end
- vma
->vm_start
;
1846 pfn
+= vma
->vm_pgoff
;
1847 return io_remap_pfn_range(vma
, vma
->vm_start
, pfn
, vm_len
, vma
->vm_page_prot
);
1849 EXPORT_SYMBOL(vm_iomap_memory
);
1851 int remap_vmalloc_range(struct vm_area_struct
*vma
, void *addr
,
1852 unsigned long pgoff
)
1854 unsigned int size
= vma
->vm_end
- vma
->vm_start
;
1856 if (!(vma
->vm_flags
& VM_USERMAP
))
1859 vma
->vm_start
= (unsigned long)(addr
+ (pgoff
<< PAGE_SHIFT
));
1860 vma
->vm_end
= vma
->vm_start
+ size
;
1864 EXPORT_SYMBOL(remap_vmalloc_range
);
1866 unsigned long arch_get_unmapped_area(struct file
*file
, unsigned long addr
,
1867 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1872 void arch_unmap_area(struct mm_struct
*mm
, unsigned long addr
)
1876 void unmap_mapping_range(struct address_space
*mapping
,
1877 loff_t
const holebegin
, loff_t
const holelen
,
1881 EXPORT_SYMBOL(unmap_mapping_range
);
1884 * Check that a process has enough memory to allocate a new virtual
1885 * mapping. 0 means there is enough memory for the allocation to
1886 * succeed and -ENOMEM implies there is not.
1888 * We currently support three overcommit policies, which are set via the
1889 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1891 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1892 * Additional code 2002 Jul 20 by Robert Love.
1894 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1896 * Note this is a helper function intended to be used by LSMs which
1897 * wish to use this logic.
1899 int __vm_enough_memory(struct mm_struct
*mm
, long pages
, int cap_sys_admin
)
1901 unsigned long free
, allowed
, reserve
;
1903 vm_acct_memory(pages
);
1906 * Sometimes we want to use more memory than we have
1908 if (sysctl_overcommit_memory
== OVERCOMMIT_ALWAYS
)
1911 if (sysctl_overcommit_memory
== OVERCOMMIT_GUESS
) {
1912 free
= global_page_state(NR_FREE_PAGES
);
1913 free
+= global_page_state(NR_FILE_PAGES
);
1916 * shmem pages shouldn't be counted as free in this
1917 * case, they can't be purged, only swapped out, and
1918 * that won't affect the overall amount of available
1919 * memory in the system.
1921 free
-= global_page_state(NR_SHMEM
);
1923 free
+= get_nr_swap_pages();
1926 * Any slabs which are created with the
1927 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1928 * which are reclaimable, under pressure. The dentry
1929 * cache and most inode caches should fall into this
1931 free
+= global_page_state(NR_SLAB_RECLAIMABLE
);
1934 * Leave reserved pages. The pages are not for anonymous pages.
1936 if (free
<= totalreserve_pages
)
1939 free
-= totalreserve_pages
;
1942 * Reserve some for root
1945 free
-= sysctl_admin_reserve_kbytes
>> (PAGE_SHIFT
- 10);
1953 allowed
= totalram_pages
* sysctl_overcommit_ratio
/ 100;
1955 * Reserve some 3% for root
1958 allowed
-= sysctl_admin_reserve_kbytes
>> (PAGE_SHIFT
- 10);
1959 allowed
+= total_swap_pages
;
1962 * Don't let a single process grow so big a user can't recover
1965 reserve
= sysctl_user_reserve_kbytes
>> (PAGE_SHIFT
- 10);
1966 allowed
-= min(mm
->total_vm
/ 32, reserve
);
1969 if (percpu_counter_read_positive(&vm_committed_as
) < allowed
)
1973 vm_unacct_memory(pages
);
1978 int in_gate_area_no_mm(unsigned long addr
)
1983 int filemap_fault(struct vm_area_struct
*vma
, struct vm_fault
*vmf
)
1988 EXPORT_SYMBOL(filemap_fault
);
1990 int generic_file_remap_pages(struct vm_area_struct
*vma
, unsigned long addr
,
1991 unsigned long size
, pgoff_t pgoff
)
1996 EXPORT_SYMBOL(generic_file_remap_pages
);
1998 static int __access_remote_vm(struct task_struct
*tsk
, struct mm_struct
*mm
,
1999 unsigned long addr
, void *buf
, int len
, int write
)
2001 struct vm_area_struct
*vma
;
2003 down_read(&mm
->mmap_sem
);
2005 /* the access must start within one of the target process's mappings */
2006 vma
= find_vma(mm
, addr
);
2008 /* don't overrun this mapping */
2009 if (addr
+ len
>= vma
->vm_end
)
2010 len
= vma
->vm_end
- addr
;
2012 /* only read or write mappings where it is permitted */
2013 if (write
&& vma
->vm_flags
& VM_MAYWRITE
)
2014 copy_to_user_page(vma
, NULL
, addr
,
2015 (void *) addr
, buf
, len
);
2016 else if (!write
&& vma
->vm_flags
& VM_MAYREAD
)
2017 copy_from_user_page(vma
, NULL
, addr
,
2018 buf
, (void *) addr
, len
);
2025 up_read(&mm
->mmap_sem
);
2031 * @access_remote_vm - access another process' address space
2032 * @mm: the mm_struct of the target address space
2033 * @addr: start address to access
2034 * @buf: source or destination buffer
2035 * @len: number of bytes to transfer
2036 * @write: whether the access is a write
2038 * The caller must hold a reference on @mm.
2040 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
2041 void *buf
, int len
, int write
)
2043 return __access_remote_vm(NULL
, mm
, addr
, buf
, len
, write
);
2047 * Access another process' address space.
2048 * - source/target buffer must be kernel space
2050 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
, void *buf
, int len
, int write
)
2052 struct mm_struct
*mm
;
2054 if (addr
+ len
< addr
)
2057 mm
= get_task_mm(tsk
);
2061 len
= __access_remote_vm(tsk
, mm
, addr
, buf
, len
, write
);
2068 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2069 * @inode: The inode to check
2070 * @size: The current filesize of the inode
2071 * @newsize: The proposed filesize of the inode
2073 * Check the shared mappings on an inode on behalf of a shrinking truncate to
2074 * make sure that that any outstanding VMAs aren't broken and then shrink the
2075 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2076 * automatically grant mappings that are too large.
2078 int nommu_shrink_inode_mappings(struct inode
*inode
, size_t size
,
2081 struct vm_area_struct
*vma
;
2082 struct vm_region
*region
;
2084 size_t r_size
, r_top
;
2086 low
= newsize
>> PAGE_SHIFT
;
2087 high
= (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
2089 down_write(&nommu_region_sem
);
2090 mutex_lock(&inode
->i_mapping
->i_mmap_mutex
);
2092 /* search for VMAs that fall within the dead zone */
2093 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, low
, high
) {
2094 /* found one - only interested if it's shared out of the page
2096 if (vma
->vm_flags
& VM_SHARED
) {
2097 mutex_unlock(&inode
->i_mapping
->i_mmap_mutex
);
2098 up_write(&nommu_region_sem
);
2099 return -ETXTBSY
; /* not quite true, but near enough */
2103 /* reduce any regions that overlap the dead zone - if in existence,
2104 * these will be pointed to by VMAs that don't overlap the dead zone
2106 * we don't check for any regions that start beyond the EOF as there
2109 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
,
2111 if (!(vma
->vm_flags
& VM_SHARED
))
2114 region
= vma
->vm_region
;
2115 r_size
= region
->vm_top
- region
->vm_start
;
2116 r_top
= (region
->vm_pgoff
<< PAGE_SHIFT
) + r_size
;
2118 if (r_top
> newsize
) {
2119 region
->vm_top
-= r_top
- newsize
;
2120 if (region
->vm_end
> region
->vm_top
)
2121 region
->vm_end
= region
->vm_top
;
2125 mutex_unlock(&inode
->i_mapping
->i_mmap_mutex
);
2126 up_write(&nommu_region_sem
);
2131 * Initialise sysctl_user_reserve_kbytes.
2133 * This is intended to prevent a user from starting a single memory hogging
2134 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
2137 * The default value is min(3% of free memory, 128MB)
2138 * 128MB is enough to recover with sshd/login, bash, and top/kill.
2140 static int __meminit
init_user_reserve(void)
2142 unsigned long free_kbytes
;
2144 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
2146 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
2149 module_init(init_user_reserve
)
2152 * Initialise sysctl_admin_reserve_kbytes.
2154 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
2155 * to log in and kill a memory hogging process.
2157 * Systems with more than 256MB will reserve 8MB, enough to recover
2158 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
2159 * only reserve 3% of free pages by default.
2161 static int __meminit
init_admin_reserve(void)
2163 unsigned long free_kbytes
;
2165 free_kbytes
= global_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
2167 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
2170 module_init(init_admin_reserve
)