1 // SPDX-License-Identifier: GPL-2.0-only
5 * Replacement code for mm functions to support CPU's that don't
6 * have any form of memory management unit (thus no virtual memory).
8 * See Documentation/nommu-mmap.txt
10 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
11 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
12 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
13 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com>
14 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
19 #include <linux/export.h>
21 #include <linux/sched/mm.h>
22 #include <linux/vmacache.h>
23 #include <linux/mman.h>
24 #include <linux/swap.h>
25 #include <linux/file.h>
26 #include <linux/highmem.h>
27 #include <linux/pagemap.h>
28 #include <linux/slab.h>
29 #include <linux/vmalloc.h>
30 #include <linux/blkdev.h>
31 #include <linux/backing-dev.h>
32 #include <linux/compiler.h>
33 #include <linux/mount.h>
34 #include <linux/personality.h>
35 #include <linux/security.h>
36 #include <linux/syscalls.h>
37 #include <linux/audit.h>
38 #include <linux/printk.h>
40 #include <linux/uaccess.h>
42 #include <asm/tlbflush.h>
43 #include <asm/mmu_context.h>
47 EXPORT_SYMBOL(high_memory
);
49 unsigned long max_mapnr
;
50 EXPORT_SYMBOL(max_mapnr
);
51 unsigned long highest_memmap_pfn
;
52 int sysctl_nr_trim_pages
= CONFIG_NOMMU_INITIAL_TRIM_EXCESS
;
53 int heap_stack_gap
= 0;
55 atomic_long_t mmap_pages_allocated
;
57 EXPORT_SYMBOL(mem_map
);
59 /* list of mapped, potentially shareable regions */
60 static struct kmem_cache
*vm_region_jar
;
61 struct rb_root nommu_region_tree
= RB_ROOT
;
62 DECLARE_RWSEM(nommu_region_sem
);
64 const struct vm_operations_struct generic_file_vm_ops
= {
68 * Return the total memory allocated for this pointer, not
69 * just what the caller asked for.
71 * Doesn't have to be accurate, i.e. may have races.
73 unsigned int kobjsize(const void *objp
)
78 * If the object we have should not have ksize performed on it,
81 if (!objp
|| !virt_addr_valid(objp
))
84 page
= virt_to_head_page(objp
);
87 * If the allocator sets PageSlab, we know the pointer came from
94 * If it's not a compound page, see if we have a matching VMA
95 * region. This test is intentionally done in reverse order,
96 * so if there's no VMA, we still fall through and hand back
97 * PAGE_SIZE for 0-order pages.
99 if (!PageCompound(page
)) {
100 struct vm_area_struct
*vma
;
102 vma
= find_vma(current
->mm
, (unsigned long)objp
);
104 return vma
->vm_end
- vma
->vm_start
;
108 * The ksize() function is only guaranteed to work for pointers
109 * returned by kmalloc(). So handle arbitrary pointers here.
111 return page_size(page
);
115 * follow_pfn - look up PFN at a user virtual address
116 * @vma: memory mapping
117 * @address: user virtual address
118 * @pfn: location to store found PFN
120 * Only IO mappings and raw PFN mappings are allowed.
122 * Returns zero and the pfn at @pfn on success, -ve otherwise.
124 int follow_pfn(struct vm_area_struct
*vma
, unsigned long address
,
127 if (!(vma
->vm_flags
& (VM_IO
| VM_PFNMAP
)))
130 *pfn
= address
>> PAGE_SHIFT
;
133 EXPORT_SYMBOL(follow_pfn
);
135 LIST_HEAD(vmap_area_list
);
137 void vfree(const void *addr
)
141 EXPORT_SYMBOL(vfree
);
143 void *__vmalloc(unsigned long size
, gfp_t gfp_mask
, pgprot_t prot
)
146 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
147 * returns only a logical address.
149 return kmalloc(size
, (gfp_mask
| __GFP_COMP
) & ~__GFP_HIGHMEM
);
151 EXPORT_SYMBOL(__vmalloc
);
153 void *__vmalloc_node_flags(unsigned long size
, int node
, gfp_t flags
)
155 return __vmalloc(size
, flags
, PAGE_KERNEL
);
158 void *vmalloc_user(unsigned long size
)
162 ret
= __vmalloc(size
, GFP_KERNEL
| __GFP_ZERO
, PAGE_KERNEL
);
164 struct vm_area_struct
*vma
;
166 down_write(¤t
->mm
->mmap_sem
);
167 vma
= find_vma(current
->mm
, (unsigned long)ret
);
169 vma
->vm_flags
|= VM_USERMAP
;
170 up_write(¤t
->mm
->mmap_sem
);
175 EXPORT_SYMBOL(vmalloc_user
);
177 struct page
*vmalloc_to_page(const void *addr
)
179 return virt_to_page(addr
);
181 EXPORT_SYMBOL(vmalloc_to_page
);
183 unsigned long vmalloc_to_pfn(const void *addr
)
185 return page_to_pfn(virt_to_page(addr
));
187 EXPORT_SYMBOL(vmalloc_to_pfn
);
189 long vread(char *buf
, char *addr
, unsigned long count
)
191 /* Don't allow overflow */
192 if ((unsigned long) buf
+ count
< count
)
193 count
= -(unsigned long) buf
;
195 memcpy(buf
, addr
, count
);
199 long vwrite(char *buf
, char *addr
, unsigned long count
)
201 /* Don't allow overflow */
202 if ((unsigned long) addr
+ count
< count
)
203 count
= -(unsigned long) addr
;
205 memcpy(addr
, buf
, count
);
210 * vmalloc - allocate virtually contiguous memory
212 * @size: allocation size
214 * Allocate enough pages to cover @size from the page level
215 * allocator and map them into contiguous kernel virtual space.
217 * For tight control over page level allocator and protection flags
218 * use __vmalloc() instead.
220 void *vmalloc(unsigned long size
)
222 return __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
, PAGE_KERNEL
);
224 EXPORT_SYMBOL(vmalloc
);
227 * vzalloc - allocate virtually contiguous memory with zero fill
229 * @size: allocation size
231 * Allocate enough pages to cover @size from the page level
232 * allocator and map them into contiguous kernel virtual space.
233 * The memory allocated is set to zero.
235 * For tight control over page level allocator and protection flags
236 * use __vmalloc() instead.
238 void *vzalloc(unsigned long size
)
240 return __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
| __GFP_ZERO
,
243 EXPORT_SYMBOL(vzalloc
);
246 * vmalloc_node - allocate memory on a specific node
247 * @size: allocation size
250 * Allocate enough pages to cover @size from the page level
251 * allocator and map them into contiguous kernel virtual space.
253 * For tight control over page level allocator and protection flags
254 * use __vmalloc() instead.
256 void *vmalloc_node(unsigned long size
, int node
)
258 return vmalloc(size
);
260 EXPORT_SYMBOL(vmalloc_node
);
263 * vzalloc_node - allocate memory on a specific node with zero fill
264 * @size: allocation size
267 * Allocate enough pages to cover @size from the page level
268 * allocator and map them into contiguous kernel virtual space.
269 * The memory allocated is set to zero.
271 * For tight control over page level allocator and protection flags
272 * use __vmalloc() instead.
274 void *vzalloc_node(unsigned long size
, int node
)
276 return vzalloc(size
);
278 EXPORT_SYMBOL(vzalloc_node
);
281 * vmalloc_exec - allocate virtually contiguous, executable memory
282 * @size: allocation size
284 * Kernel-internal function to allocate enough pages to cover @size
285 * the page level allocator and map them into contiguous and
286 * executable kernel virtual space.
288 * For tight control over page level allocator and protection flags
289 * use __vmalloc() instead.
292 void *vmalloc_exec(unsigned long size
)
294 return __vmalloc(size
, GFP_KERNEL
| __GFP_HIGHMEM
, PAGE_KERNEL_EXEC
);
298 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
299 * @size: allocation size
301 * Allocate enough 32bit PA addressable pages to cover @size from the
302 * page level allocator and map them into contiguous kernel virtual space.
304 void *vmalloc_32(unsigned long size
)
306 return __vmalloc(size
, GFP_KERNEL
, PAGE_KERNEL
);
308 EXPORT_SYMBOL(vmalloc_32
);
311 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
312 * @size: allocation size
314 * The resulting memory area is 32bit addressable and zeroed so it can be
315 * mapped to userspace without leaking data.
317 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
318 * remap_vmalloc_range() are permissible.
320 void *vmalloc_32_user(unsigned long size
)
323 * We'll have to sort out the ZONE_DMA bits for 64-bit,
324 * but for now this can simply use vmalloc_user() directly.
326 return vmalloc_user(size
);
328 EXPORT_SYMBOL(vmalloc_32_user
);
330 void *vmap(struct page
**pages
, unsigned int count
, unsigned long flags
, pgprot_t prot
)
337 void vunmap(const void *addr
)
341 EXPORT_SYMBOL(vunmap
);
343 void *vm_map_ram(struct page
**pages
, unsigned int count
, int node
, pgprot_t prot
)
348 EXPORT_SYMBOL(vm_map_ram
);
350 void vm_unmap_ram(const void *mem
, unsigned int count
)
354 EXPORT_SYMBOL(vm_unmap_ram
);
356 void vm_unmap_aliases(void)
359 EXPORT_SYMBOL_GPL(vm_unmap_aliases
);
362 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
365 void __weak
vmalloc_sync_all(void)
369 struct vm_struct
*alloc_vm_area(size_t size
, pte_t
**ptes
)
374 EXPORT_SYMBOL_GPL(alloc_vm_area
);
376 void free_vm_area(struct vm_struct
*area
)
380 EXPORT_SYMBOL_GPL(free_vm_area
);
382 int vm_insert_page(struct vm_area_struct
*vma
, unsigned long addr
,
387 EXPORT_SYMBOL(vm_insert_page
);
389 int vm_map_pages(struct vm_area_struct
*vma
, struct page
**pages
,
394 EXPORT_SYMBOL(vm_map_pages
);
396 int vm_map_pages_zero(struct vm_area_struct
*vma
, struct page
**pages
,
401 EXPORT_SYMBOL(vm_map_pages_zero
);
404 * sys_brk() for the most part doesn't need the global kernel
405 * lock, except when an application is doing something nasty
406 * like trying to un-brk an area that has already been mapped
407 * to a regular file. in this case, the unmapping will need
408 * to invoke file system routines that need the global lock.
410 SYSCALL_DEFINE1(brk
, unsigned long, brk
)
412 struct mm_struct
*mm
= current
->mm
;
414 if (brk
< mm
->start_brk
|| brk
> mm
->context
.end_brk
)
421 * Always allow shrinking brk
423 if (brk
<= mm
->brk
) {
429 * Ok, looks good - let it rip.
431 flush_icache_range(mm
->brk
, brk
);
432 return mm
->brk
= brk
;
436 * initialise the percpu counter for VM and region record slabs
438 void __init
mmap_init(void)
442 ret
= percpu_counter_init(&vm_committed_as
, 0, GFP_KERNEL
);
444 vm_region_jar
= KMEM_CACHE(vm_region
, SLAB_PANIC
|SLAB_ACCOUNT
);
448 * validate the region tree
449 * - the caller must hold the region lock
451 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
452 static noinline
void validate_nommu_regions(void)
454 struct vm_region
*region
, *last
;
455 struct rb_node
*p
, *lastp
;
457 lastp
= rb_first(&nommu_region_tree
);
461 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
462 BUG_ON(last
->vm_end
<= last
->vm_start
);
463 BUG_ON(last
->vm_top
< last
->vm_end
);
465 while ((p
= rb_next(lastp
))) {
466 region
= rb_entry(p
, struct vm_region
, vm_rb
);
467 last
= rb_entry(lastp
, struct vm_region
, vm_rb
);
469 BUG_ON(region
->vm_end
<= region
->vm_start
);
470 BUG_ON(region
->vm_top
< region
->vm_end
);
471 BUG_ON(region
->vm_start
< last
->vm_top
);
477 static void validate_nommu_regions(void)
483 * add a region into the global tree
485 static void add_nommu_region(struct vm_region
*region
)
487 struct vm_region
*pregion
;
488 struct rb_node
**p
, *parent
;
490 validate_nommu_regions();
493 p
= &nommu_region_tree
.rb_node
;
496 pregion
= rb_entry(parent
, struct vm_region
, vm_rb
);
497 if (region
->vm_start
< pregion
->vm_start
)
499 else if (region
->vm_start
> pregion
->vm_start
)
501 else if (pregion
== region
)
507 rb_link_node(®ion
->vm_rb
, parent
, p
);
508 rb_insert_color(®ion
->vm_rb
, &nommu_region_tree
);
510 validate_nommu_regions();
514 * delete a region from the global tree
516 static void delete_nommu_region(struct vm_region
*region
)
518 BUG_ON(!nommu_region_tree
.rb_node
);
520 validate_nommu_regions();
521 rb_erase(®ion
->vm_rb
, &nommu_region_tree
);
522 validate_nommu_regions();
526 * free a contiguous series of pages
528 static void free_page_series(unsigned long from
, unsigned long to
)
530 for (; from
< to
; from
+= PAGE_SIZE
) {
531 struct page
*page
= virt_to_page(from
);
533 atomic_long_dec(&mmap_pages_allocated
);
539 * release a reference to a region
540 * - the caller must hold the region semaphore for writing, which this releases
541 * - the region may not have been added to the tree yet, in which case vm_top
542 * will equal vm_start
544 static void __put_nommu_region(struct vm_region
*region
)
545 __releases(nommu_region_sem
)
547 BUG_ON(!nommu_region_tree
.rb_node
);
549 if (--region
->vm_usage
== 0) {
550 if (region
->vm_top
> region
->vm_start
)
551 delete_nommu_region(region
);
552 up_write(&nommu_region_sem
);
555 fput(region
->vm_file
);
557 /* IO memory and memory shared directly out of the pagecache
558 * from ramfs/tmpfs mustn't be released here */
559 if (region
->vm_flags
& VM_MAPPED_COPY
)
560 free_page_series(region
->vm_start
, region
->vm_top
);
561 kmem_cache_free(vm_region_jar
, region
);
563 up_write(&nommu_region_sem
);
568 * release a reference to a region
570 static void put_nommu_region(struct vm_region
*region
)
572 down_write(&nommu_region_sem
);
573 __put_nommu_region(region
);
577 * add a VMA into a process's mm_struct in the appropriate place in the list
578 * and tree and add to the address space's page tree also if not an anonymous
580 * - should be called with mm->mmap_sem held writelocked
582 static void add_vma_to_mm(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
584 struct vm_area_struct
*pvma
, *prev
;
585 struct address_space
*mapping
;
586 struct rb_node
**p
, *parent
, *rb_prev
;
588 BUG_ON(!vma
->vm_region
);
593 /* add the VMA to the mapping */
595 mapping
= vma
->vm_file
->f_mapping
;
597 i_mmap_lock_write(mapping
);
598 flush_dcache_mmap_lock(mapping
);
599 vma_interval_tree_insert(vma
, &mapping
->i_mmap
);
600 flush_dcache_mmap_unlock(mapping
);
601 i_mmap_unlock_write(mapping
);
604 /* add the VMA to the tree */
605 parent
= rb_prev
= NULL
;
606 p
= &mm
->mm_rb
.rb_node
;
609 pvma
= rb_entry(parent
, struct vm_area_struct
, vm_rb
);
611 /* sort by: start addr, end addr, VMA struct addr in that order
612 * (the latter is necessary as we may get identical VMAs) */
613 if (vma
->vm_start
< pvma
->vm_start
)
615 else if (vma
->vm_start
> pvma
->vm_start
) {
618 } else if (vma
->vm_end
< pvma
->vm_end
)
620 else if (vma
->vm_end
> pvma
->vm_end
) {
623 } else if (vma
< pvma
)
625 else if (vma
> pvma
) {
632 rb_link_node(&vma
->vm_rb
, parent
, p
);
633 rb_insert_color(&vma
->vm_rb
, &mm
->mm_rb
);
635 /* add VMA to the VMA list also */
638 prev
= rb_entry(rb_prev
, struct vm_area_struct
, vm_rb
);
640 __vma_link_list(mm
, vma
, prev
, parent
);
644 * delete a VMA from its owning mm_struct and address space
646 static void delete_vma_from_mm(struct vm_area_struct
*vma
)
649 struct address_space
*mapping
;
650 struct mm_struct
*mm
= vma
->vm_mm
;
651 struct task_struct
*curr
= current
;
654 for (i
= 0; i
< VMACACHE_SIZE
; i
++) {
655 /* if the vma is cached, invalidate the entire cache */
656 if (curr
->vmacache
.vmas
[i
] == vma
) {
657 vmacache_invalidate(mm
);
662 /* remove the VMA from the mapping */
664 mapping
= vma
->vm_file
->f_mapping
;
666 i_mmap_lock_write(mapping
);
667 flush_dcache_mmap_lock(mapping
);
668 vma_interval_tree_remove(vma
, &mapping
->i_mmap
);
669 flush_dcache_mmap_unlock(mapping
);
670 i_mmap_unlock_write(mapping
);
673 /* remove from the MM's tree and list */
674 rb_erase(&vma
->vm_rb
, &mm
->mm_rb
);
677 vma
->vm_prev
->vm_next
= vma
->vm_next
;
679 mm
->mmap
= vma
->vm_next
;
682 vma
->vm_next
->vm_prev
= vma
->vm_prev
;
686 * destroy a VMA record
688 static void delete_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
)
690 if (vma
->vm_ops
&& vma
->vm_ops
->close
)
691 vma
->vm_ops
->close(vma
);
694 put_nommu_region(vma
->vm_region
);
699 * look up the first VMA in which addr resides, NULL if none
700 * - should be called with mm->mmap_sem at least held readlocked
702 struct vm_area_struct
*find_vma(struct mm_struct
*mm
, unsigned long addr
)
704 struct vm_area_struct
*vma
;
706 /* check the cache first */
707 vma
= vmacache_find(mm
, addr
);
711 /* trawl the list (there may be multiple mappings in which addr
713 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
714 if (vma
->vm_start
> addr
)
716 if (vma
->vm_end
> addr
) {
717 vmacache_update(addr
, vma
);
724 EXPORT_SYMBOL(find_vma
);
728 * - we don't extend stack VMAs under NOMMU conditions
730 struct vm_area_struct
*find_extend_vma(struct mm_struct
*mm
, unsigned long addr
)
732 return find_vma(mm
, addr
);
736 * expand a stack to a given address
737 * - not supported under NOMMU conditions
739 int expand_stack(struct vm_area_struct
*vma
, unsigned long address
)
745 * look up the first VMA exactly that exactly matches addr
746 * - should be called with mm->mmap_sem at least held readlocked
748 static struct vm_area_struct
*find_vma_exact(struct mm_struct
*mm
,
752 struct vm_area_struct
*vma
;
753 unsigned long end
= addr
+ len
;
755 /* check the cache first */
756 vma
= vmacache_find_exact(mm
, addr
, end
);
760 /* trawl the list (there may be multiple mappings in which addr
762 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
763 if (vma
->vm_start
< addr
)
765 if (vma
->vm_start
> addr
)
767 if (vma
->vm_end
== end
) {
768 vmacache_update(addr
, vma
);
777 * determine whether a mapping should be permitted and, if so, what sort of
778 * mapping we're capable of supporting
780 static int validate_mmap_request(struct file
*file
,
786 unsigned long *_capabilities
)
788 unsigned long capabilities
, rlen
;
791 /* do the simple checks first */
792 if (flags
& MAP_FIXED
)
795 if ((flags
& MAP_TYPE
) != MAP_PRIVATE
&&
796 (flags
& MAP_TYPE
) != MAP_SHARED
)
802 /* Careful about overflows.. */
803 rlen
= PAGE_ALIGN(len
);
804 if (!rlen
|| rlen
> TASK_SIZE
)
807 /* offset overflow? */
808 if ((pgoff
+ (rlen
>> PAGE_SHIFT
)) < pgoff
)
812 /* files must support mmap */
813 if (!file
->f_op
->mmap
)
816 /* work out if what we've got could possibly be shared
817 * - we support chardevs that provide their own "memory"
818 * - we support files/blockdevs that are memory backed
820 if (file
->f_op
->mmap_capabilities
) {
821 capabilities
= file
->f_op
->mmap_capabilities(file
);
823 /* no explicit capabilities set, so assume some
825 switch (file_inode(file
)->i_mode
& S_IFMT
) {
828 capabilities
= NOMMU_MAP_COPY
;
843 /* eliminate any capabilities that we can't support on this
845 if (!file
->f_op
->get_unmapped_area
)
846 capabilities
&= ~NOMMU_MAP_DIRECT
;
847 if (!(file
->f_mode
& FMODE_CAN_READ
))
848 capabilities
&= ~NOMMU_MAP_COPY
;
850 /* The file shall have been opened with read permission. */
851 if (!(file
->f_mode
& FMODE_READ
))
854 if (flags
& MAP_SHARED
) {
855 /* do checks for writing, appending and locking */
856 if ((prot
& PROT_WRITE
) &&
857 !(file
->f_mode
& FMODE_WRITE
))
860 if (IS_APPEND(file_inode(file
)) &&
861 (file
->f_mode
& FMODE_WRITE
))
864 if (locks_verify_locked(file
))
867 if (!(capabilities
& NOMMU_MAP_DIRECT
))
870 /* we mustn't privatise shared mappings */
871 capabilities
&= ~NOMMU_MAP_COPY
;
873 /* we're going to read the file into private memory we
875 if (!(capabilities
& NOMMU_MAP_COPY
))
878 /* we don't permit a private writable mapping to be
879 * shared with the backing device */
880 if (prot
& PROT_WRITE
)
881 capabilities
&= ~NOMMU_MAP_DIRECT
;
884 if (capabilities
& NOMMU_MAP_DIRECT
) {
885 if (((prot
& PROT_READ
) && !(capabilities
& NOMMU_MAP_READ
)) ||
886 ((prot
& PROT_WRITE
) && !(capabilities
& NOMMU_MAP_WRITE
)) ||
887 ((prot
& PROT_EXEC
) && !(capabilities
& NOMMU_MAP_EXEC
))
889 capabilities
&= ~NOMMU_MAP_DIRECT
;
890 if (flags
& MAP_SHARED
) {
891 pr_warn("MAP_SHARED not completely supported on !MMU\n");
897 /* handle executable mappings and implied executable
899 if (path_noexec(&file
->f_path
)) {
900 if (prot
& PROT_EXEC
)
902 } else if ((prot
& PROT_READ
) && !(prot
& PROT_EXEC
)) {
903 /* handle implication of PROT_EXEC by PROT_READ */
904 if (current
->personality
& READ_IMPLIES_EXEC
) {
905 if (capabilities
& NOMMU_MAP_EXEC
)
908 } else if ((prot
& PROT_READ
) &&
909 (prot
& PROT_EXEC
) &&
910 !(capabilities
& NOMMU_MAP_EXEC
)
912 /* backing file is not executable, try to copy */
913 capabilities
&= ~NOMMU_MAP_DIRECT
;
916 /* anonymous mappings are always memory backed and can be
919 capabilities
= NOMMU_MAP_COPY
;
921 /* handle PROT_EXEC implication by PROT_READ */
922 if ((prot
& PROT_READ
) &&
923 (current
->personality
& READ_IMPLIES_EXEC
))
927 /* allow the security API to have its say */
928 ret
= security_mmap_addr(addr
);
933 *_capabilities
= capabilities
;
938 * we've determined that we can make the mapping, now translate what we
939 * now know into VMA flags
941 static unsigned long determine_vm_flags(struct file
*file
,
944 unsigned long capabilities
)
946 unsigned long vm_flags
;
948 vm_flags
= calc_vm_prot_bits(prot
, 0) | calc_vm_flag_bits(flags
);
949 /* vm_flags |= mm->def_flags; */
951 if (!(capabilities
& NOMMU_MAP_DIRECT
)) {
952 /* attempt to share read-only copies of mapped file chunks */
953 vm_flags
|= VM_MAYREAD
| VM_MAYWRITE
| VM_MAYEXEC
;
954 if (file
&& !(prot
& PROT_WRITE
))
955 vm_flags
|= VM_MAYSHARE
;
957 /* overlay a shareable mapping on the backing device or inode
958 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
960 vm_flags
|= VM_MAYSHARE
| (capabilities
& NOMMU_VMFLAGS
);
961 if (flags
& MAP_SHARED
)
962 vm_flags
|= VM_SHARED
;
965 /* refuse to let anyone share private mappings with this process if
966 * it's being traced - otherwise breakpoints set in it may interfere
967 * with another untraced process
969 if ((flags
& MAP_PRIVATE
) && current
->ptrace
)
970 vm_flags
&= ~VM_MAYSHARE
;
976 * set up a shared mapping on a file (the driver or filesystem provides and
979 static int do_mmap_shared_file(struct vm_area_struct
*vma
)
983 ret
= call_mmap(vma
->vm_file
, vma
);
985 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
991 /* getting -ENOSYS indicates that direct mmap isn't possible (as
992 * opposed to tried but failed) so we can only give a suitable error as
993 * it's not possible to make a private copy if MAP_SHARED was given */
998 * set up a private mapping or an anonymous shared mapping
1000 static int do_mmap_private(struct vm_area_struct
*vma
,
1001 struct vm_region
*region
,
1003 unsigned long capabilities
)
1005 unsigned long total
, point
;
1009 /* invoke the file's mapping function so that it can keep track of
1010 * shared mappings on devices or memory
1011 * - VM_MAYSHARE will be set if it may attempt to share
1013 if (capabilities
& NOMMU_MAP_DIRECT
) {
1014 ret
= call_mmap(vma
->vm_file
, vma
);
1016 /* shouldn't return success if we're not sharing */
1017 BUG_ON(!(vma
->vm_flags
& VM_MAYSHARE
));
1018 vma
->vm_region
->vm_top
= vma
->vm_region
->vm_end
;
1024 /* getting an ENOSYS error indicates that direct mmap isn't
1025 * possible (as opposed to tried but failed) so we'll try to
1026 * make a private copy of the data and map that instead */
1030 /* allocate some memory to hold the mapping
1031 * - note that this may not return a page-aligned address if the object
1032 * we're allocating is smaller than a page
1034 order
= get_order(len
);
1036 point
= len
>> PAGE_SHIFT
;
1038 /* we don't want to allocate a power-of-2 sized page set */
1039 if (sysctl_nr_trim_pages
&& total
- point
>= sysctl_nr_trim_pages
)
1042 base
= alloc_pages_exact(total
<< PAGE_SHIFT
, GFP_KERNEL
);
1046 atomic_long_add(total
, &mmap_pages_allocated
);
1048 region
->vm_flags
= vma
->vm_flags
|= VM_MAPPED_COPY
;
1049 region
->vm_start
= (unsigned long) base
;
1050 region
->vm_end
= region
->vm_start
+ len
;
1051 region
->vm_top
= region
->vm_start
+ (total
<< PAGE_SHIFT
);
1053 vma
->vm_start
= region
->vm_start
;
1054 vma
->vm_end
= region
->vm_start
+ len
;
1057 /* read the contents of a file into the copy */
1060 fpos
= vma
->vm_pgoff
;
1061 fpos
<<= PAGE_SHIFT
;
1063 ret
= kernel_read(vma
->vm_file
, base
, len
, &fpos
);
1067 /* clear the last little bit */
1069 memset(base
+ ret
, 0, len
- ret
);
1072 vma_set_anonymous(vma
);
1078 free_page_series(region
->vm_start
, region
->vm_top
);
1079 region
->vm_start
= vma
->vm_start
= 0;
1080 region
->vm_end
= vma
->vm_end
= 0;
1085 pr_err("Allocation of length %lu from process %d (%s) failed\n",
1086 len
, current
->pid
, current
->comm
);
1087 show_free_areas(0, NULL
);
1092 * handle mapping creation for uClinux
1094 unsigned long do_mmap(struct file
*file
,
1098 unsigned long flags
,
1099 vm_flags_t vm_flags
,
1100 unsigned long pgoff
,
1101 unsigned long *populate
,
1102 struct list_head
*uf
)
1104 struct vm_area_struct
*vma
;
1105 struct vm_region
*region
;
1107 unsigned long capabilities
, result
;
1112 /* decide whether we should attempt the mapping, and if so what sort of
1114 ret
= validate_mmap_request(file
, addr
, len
, prot
, flags
, pgoff
,
1119 /* we ignore the address hint */
1121 len
= PAGE_ALIGN(len
);
1123 /* we've determined that we can make the mapping, now translate what we
1124 * now know into VMA flags */
1125 vm_flags
|= determine_vm_flags(file
, prot
, flags
, capabilities
);
1127 /* we're going to need to record the mapping */
1128 region
= kmem_cache_zalloc(vm_region_jar
, GFP_KERNEL
);
1130 goto error_getting_region
;
1132 vma
= vm_area_alloc(current
->mm
);
1134 goto error_getting_vma
;
1136 region
->vm_usage
= 1;
1137 region
->vm_flags
= vm_flags
;
1138 region
->vm_pgoff
= pgoff
;
1140 vma
->vm_flags
= vm_flags
;
1141 vma
->vm_pgoff
= pgoff
;
1144 region
->vm_file
= get_file(file
);
1145 vma
->vm_file
= get_file(file
);
1148 down_write(&nommu_region_sem
);
1150 /* if we want to share, we need to check for regions created by other
1151 * mmap() calls that overlap with our proposed mapping
1152 * - we can only share with a superset match on most regular files
1153 * - shared mappings on character devices and memory backed files are
1154 * permitted to overlap inexactly as far as we are concerned for in
1155 * these cases, sharing is handled in the driver or filesystem rather
1158 if (vm_flags
& VM_MAYSHARE
) {
1159 struct vm_region
*pregion
;
1160 unsigned long pglen
, rpglen
, pgend
, rpgend
, start
;
1162 pglen
= (len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1163 pgend
= pgoff
+ pglen
;
1165 for (rb
= rb_first(&nommu_region_tree
); rb
; rb
= rb_next(rb
)) {
1166 pregion
= rb_entry(rb
, struct vm_region
, vm_rb
);
1168 if (!(pregion
->vm_flags
& VM_MAYSHARE
))
1171 /* search for overlapping mappings on the same file */
1172 if (file_inode(pregion
->vm_file
) !=
1176 if (pregion
->vm_pgoff
>= pgend
)
1179 rpglen
= pregion
->vm_end
- pregion
->vm_start
;
1180 rpglen
= (rpglen
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1181 rpgend
= pregion
->vm_pgoff
+ rpglen
;
1182 if (pgoff
>= rpgend
)
1185 /* handle inexactly overlapping matches between
1187 if ((pregion
->vm_pgoff
!= pgoff
|| rpglen
!= pglen
) &&
1188 !(pgoff
>= pregion
->vm_pgoff
&& pgend
<= rpgend
)) {
1189 /* new mapping is not a subset of the region */
1190 if (!(capabilities
& NOMMU_MAP_DIRECT
))
1191 goto sharing_violation
;
1195 /* we've found a region we can share */
1196 pregion
->vm_usage
++;
1197 vma
->vm_region
= pregion
;
1198 start
= pregion
->vm_start
;
1199 start
+= (pgoff
- pregion
->vm_pgoff
) << PAGE_SHIFT
;
1200 vma
->vm_start
= start
;
1201 vma
->vm_end
= start
+ len
;
1203 if (pregion
->vm_flags
& VM_MAPPED_COPY
)
1204 vma
->vm_flags
|= VM_MAPPED_COPY
;
1206 ret
= do_mmap_shared_file(vma
);
1208 vma
->vm_region
= NULL
;
1211 pregion
->vm_usage
--;
1213 goto error_just_free
;
1216 fput(region
->vm_file
);
1217 kmem_cache_free(vm_region_jar
, region
);
1223 /* obtain the address at which to make a shared mapping
1224 * - this is the hook for quasi-memory character devices to
1225 * tell us the location of a shared mapping
1227 if (capabilities
& NOMMU_MAP_DIRECT
) {
1228 addr
= file
->f_op
->get_unmapped_area(file
, addr
, len
,
1230 if (IS_ERR_VALUE(addr
)) {
1233 goto error_just_free
;
1235 /* the driver refused to tell us where to site
1236 * the mapping so we'll have to attempt to copy
1239 if (!(capabilities
& NOMMU_MAP_COPY
))
1240 goto error_just_free
;
1242 capabilities
&= ~NOMMU_MAP_DIRECT
;
1244 vma
->vm_start
= region
->vm_start
= addr
;
1245 vma
->vm_end
= region
->vm_end
= addr
+ len
;
1250 vma
->vm_region
= region
;
1252 /* set up the mapping
1253 * - the region is filled in if NOMMU_MAP_DIRECT is still set
1255 if (file
&& vma
->vm_flags
& VM_SHARED
)
1256 ret
= do_mmap_shared_file(vma
);
1258 ret
= do_mmap_private(vma
, region
, len
, capabilities
);
1260 goto error_just_free
;
1261 add_nommu_region(region
);
1263 /* clear anonymous mappings that don't ask for uninitialized data */
1264 if (!vma
->vm_file
&&
1265 (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED
) ||
1266 !(flags
& MAP_UNINITIALIZED
)))
1267 memset((void *)region
->vm_start
, 0,
1268 region
->vm_end
- region
->vm_start
);
1270 /* okay... we have a mapping; now we have to register it */
1271 result
= vma
->vm_start
;
1273 current
->mm
->total_vm
+= len
>> PAGE_SHIFT
;
1276 add_vma_to_mm(current
->mm
, vma
);
1278 /* we flush the region from the icache only when the first executable
1279 * mapping of it is made */
1280 if (vma
->vm_flags
& VM_EXEC
&& !region
->vm_icache_flushed
) {
1281 flush_icache_range(region
->vm_start
, region
->vm_end
);
1282 region
->vm_icache_flushed
= true;
1285 up_write(&nommu_region_sem
);
1290 up_write(&nommu_region_sem
);
1292 if (region
->vm_file
)
1293 fput(region
->vm_file
);
1294 kmem_cache_free(vm_region_jar
, region
);
1301 up_write(&nommu_region_sem
);
1302 pr_warn("Attempt to share mismatched mappings\n");
1307 kmem_cache_free(vm_region_jar
, region
);
1308 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n",
1310 show_free_areas(0, NULL
);
1313 error_getting_region
:
1314 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n",
1316 show_free_areas(0, NULL
);
1320 unsigned long ksys_mmap_pgoff(unsigned long addr
, unsigned long len
,
1321 unsigned long prot
, unsigned long flags
,
1322 unsigned long fd
, unsigned long pgoff
)
1324 struct file
*file
= NULL
;
1325 unsigned long retval
= -EBADF
;
1327 audit_mmap_fd(fd
, flags
);
1328 if (!(flags
& MAP_ANONYMOUS
)) {
1334 flags
&= ~(MAP_EXECUTABLE
| MAP_DENYWRITE
);
1336 retval
= vm_mmap_pgoff(file
, addr
, len
, prot
, flags
, pgoff
);
1344 SYSCALL_DEFINE6(mmap_pgoff
, unsigned long, addr
, unsigned long, len
,
1345 unsigned long, prot
, unsigned long, flags
,
1346 unsigned long, fd
, unsigned long, pgoff
)
1348 return ksys_mmap_pgoff(addr
, len
, prot
, flags
, fd
, pgoff
);
1351 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1352 struct mmap_arg_struct
{
1356 unsigned long flags
;
1358 unsigned long offset
;
1361 SYSCALL_DEFINE1(old_mmap
, struct mmap_arg_struct __user
*, arg
)
1363 struct mmap_arg_struct a
;
1365 if (copy_from_user(&a
, arg
, sizeof(a
)))
1367 if (offset_in_page(a
.offset
))
1370 return ksys_mmap_pgoff(a
.addr
, a
.len
, a
.prot
, a
.flags
, a
.fd
,
1371 a
.offset
>> PAGE_SHIFT
);
1373 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1376 * split a vma into two pieces at address 'addr', a new vma is allocated either
1377 * for the first part or the tail.
1379 int split_vma(struct mm_struct
*mm
, struct vm_area_struct
*vma
,
1380 unsigned long addr
, int new_below
)
1382 struct vm_area_struct
*new;
1383 struct vm_region
*region
;
1384 unsigned long npages
;
1386 /* we're only permitted to split anonymous regions (these should have
1387 * only a single usage on the region) */
1391 if (mm
->map_count
>= sysctl_max_map_count
)
1394 region
= kmem_cache_alloc(vm_region_jar
, GFP_KERNEL
);
1398 new = vm_area_dup(vma
);
1400 kmem_cache_free(vm_region_jar
, region
);
1404 /* most fields are the same, copy all, and then fixup */
1405 *region
= *vma
->vm_region
;
1406 new->vm_region
= region
;
1408 npages
= (addr
- vma
->vm_start
) >> PAGE_SHIFT
;
1411 region
->vm_top
= region
->vm_end
= new->vm_end
= addr
;
1413 region
->vm_start
= new->vm_start
= addr
;
1414 region
->vm_pgoff
= new->vm_pgoff
+= npages
;
1417 if (new->vm_ops
&& new->vm_ops
->open
)
1418 new->vm_ops
->open(new);
1420 delete_vma_from_mm(vma
);
1421 down_write(&nommu_region_sem
);
1422 delete_nommu_region(vma
->vm_region
);
1424 vma
->vm_region
->vm_start
= vma
->vm_start
= addr
;
1425 vma
->vm_region
->vm_pgoff
= vma
->vm_pgoff
+= npages
;
1427 vma
->vm_region
->vm_end
= vma
->vm_end
= addr
;
1428 vma
->vm_region
->vm_top
= addr
;
1430 add_nommu_region(vma
->vm_region
);
1431 add_nommu_region(new->vm_region
);
1432 up_write(&nommu_region_sem
);
1433 add_vma_to_mm(mm
, vma
);
1434 add_vma_to_mm(mm
, new);
1439 * shrink a VMA by removing the specified chunk from either the beginning or
1442 static int shrink_vma(struct mm_struct
*mm
,
1443 struct vm_area_struct
*vma
,
1444 unsigned long from
, unsigned long to
)
1446 struct vm_region
*region
;
1448 /* adjust the VMA's pointers, which may reposition it in the MM's tree
1450 delete_vma_from_mm(vma
);
1451 if (from
> vma
->vm_start
)
1455 add_vma_to_mm(mm
, vma
);
1457 /* cut the backing region down to size */
1458 region
= vma
->vm_region
;
1459 BUG_ON(region
->vm_usage
!= 1);
1461 down_write(&nommu_region_sem
);
1462 delete_nommu_region(region
);
1463 if (from
> region
->vm_start
) {
1464 to
= region
->vm_top
;
1465 region
->vm_top
= region
->vm_end
= from
;
1467 region
->vm_start
= to
;
1469 add_nommu_region(region
);
1470 up_write(&nommu_region_sem
);
1472 free_page_series(from
, to
);
1478 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1479 * VMA, though it need not cover the whole VMA
1481 int do_munmap(struct mm_struct
*mm
, unsigned long start
, size_t len
, struct list_head
*uf
)
1483 struct vm_area_struct
*vma
;
1487 len
= PAGE_ALIGN(len
);
1493 /* find the first potentially overlapping VMA */
1494 vma
= find_vma(mm
, start
);
1498 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n",
1499 current
->pid
, current
->comm
,
1500 start
, start
+ len
- 1);
1506 /* we're allowed to split an anonymous VMA but not a file-backed one */
1509 if (start
> vma
->vm_start
)
1511 if (end
== vma
->vm_end
)
1512 goto erase_whole_vma
;
1517 /* the chunk must be a subset of the VMA found */
1518 if (start
== vma
->vm_start
&& end
== vma
->vm_end
)
1519 goto erase_whole_vma
;
1520 if (start
< vma
->vm_start
|| end
> vma
->vm_end
)
1522 if (offset_in_page(start
))
1524 if (end
!= vma
->vm_end
&& offset_in_page(end
))
1526 if (start
!= vma
->vm_start
&& end
!= vma
->vm_end
) {
1527 ret
= split_vma(mm
, vma
, start
, 1);
1531 return shrink_vma(mm
, vma
, start
, end
);
1535 delete_vma_from_mm(vma
);
1536 delete_vma(mm
, vma
);
1539 EXPORT_SYMBOL(do_munmap
);
1541 int vm_munmap(unsigned long addr
, size_t len
)
1543 struct mm_struct
*mm
= current
->mm
;
1546 down_write(&mm
->mmap_sem
);
1547 ret
= do_munmap(mm
, addr
, len
, NULL
);
1548 up_write(&mm
->mmap_sem
);
1551 EXPORT_SYMBOL(vm_munmap
);
1553 SYSCALL_DEFINE2(munmap
, unsigned long, addr
, size_t, len
)
1555 return vm_munmap(addr
, len
);
1559 * release all the mappings made in a process's VM space
1561 void exit_mmap(struct mm_struct
*mm
)
1563 struct vm_area_struct
*vma
;
1570 while ((vma
= mm
->mmap
)) {
1571 mm
->mmap
= vma
->vm_next
;
1572 delete_vma_from_mm(vma
);
1573 delete_vma(mm
, vma
);
1578 int vm_brk(unsigned long addr
, unsigned long len
)
1584 * expand (or shrink) an existing mapping, potentially moving it at the same
1585 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1587 * under NOMMU conditions, we only permit changing a mapping's size, and only
1588 * as long as it stays within the region allocated by do_mmap_private() and the
1589 * block is not shareable
1591 * MREMAP_FIXED is not supported under NOMMU conditions
1593 static unsigned long do_mremap(unsigned long addr
,
1594 unsigned long old_len
, unsigned long new_len
,
1595 unsigned long flags
, unsigned long new_addr
)
1597 struct vm_area_struct
*vma
;
1599 /* insanity checks first */
1600 old_len
= PAGE_ALIGN(old_len
);
1601 new_len
= PAGE_ALIGN(new_len
);
1602 if (old_len
== 0 || new_len
== 0)
1603 return (unsigned long) -EINVAL
;
1605 if (offset_in_page(addr
))
1608 if (flags
& MREMAP_FIXED
&& new_addr
!= addr
)
1609 return (unsigned long) -EINVAL
;
1611 vma
= find_vma_exact(current
->mm
, addr
, old_len
);
1613 return (unsigned long) -EINVAL
;
1615 if (vma
->vm_end
!= vma
->vm_start
+ old_len
)
1616 return (unsigned long) -EFAULT
;
1618 if (vma
->vm_flags
& VM_MAYSHARE
)
1619 return (unsigned long) -EPERM
;
1621 if (new_len
> vma
->vm_region
->vm_end
- vma
->vm_region
->vm_start
)
1622 return (unsigned long) -ENOMEM
;
1624 /* all checks complete - do it */
1625 vma
->vm_end
= vma
->vm_start
+ new_len
;
1626 return vma
->vm_start
;
1629 SYSCALL_DEFINE5(mremap
, unsigned long, addr
, unsigned long, old_len
,
1630 unsigned long, new_len
, unsigned long, flags
,
1631 unsigned long, new_addr
)
1635 down_write(¤t
->mm
->mmap_sem
);
1636 ret
= do_mremap(addr
, old_len
, new_len
, flags
, new_addr
);
1637 up_write(¤t
->mm
->mmap_sem
);
1641 struct page
*follow_page(struct vm_area_struct
*vma
, unsigned long address
,
1642 unsigned int foll_flags
)
1647 int remap_pfn_range(struct vm_area_struct
*vma
, unsigned long addr
,
1648 unsigned long pfn
, unsigned long size
, pgprot_t prot
)
1650 if (addr
!= (pfn
<< PAGE_SHIFT
))
1653 vma
->vm_flags
|= VM_IO
| VM_PFNMAP
| VM_DONTEXPAND
| VM_DONTDUMP
;
1656 EXPORT_SYMBOL(remap_pfn_range
);
1658 int vm_iomap_memory(struct vm_area_struct
*vma
, phys_addr_t start
, unsigned long len
)
1660 unsigned long pfn
= start
>> PAGE_SHIFT
;
1661 unsigned long vm_len
= vma
->vm_end
- vma
->vm_start
;
1663 pfn
+= vma
->vm_pgoff
;
1664 return io_remap_pfn_range(vma
, vma
->vm_start
, pfn
, vm_len
, vma
->vm_page_prot
);
1666 EXPORT_SYMBOL(vm_iomap_memory
);
1668 int remap_vmalloc_range(struct vm_area_struct
*vma
, void *addr
,
1669 unsigned long pgoff
)
1671 unsigned int size
= vma
->vm_end
- vma
->vm_start
;
1673 if (!(vma
->vm_flags
& VM_USERMAP
))
1676 vma
->vm_start
= (unsigned long)(addr
+ (pgoff
<< PAGE_SHIFT
));
1677 vma
->vm_end
= vma
->vm_start
+ size
;
1681 EXPORT_SYMBOL(remap_vmalloc_range
);
1683 unsigned long arch_get_unmapped_area(struct file
*file
, unsigned long addr
,
1684 unsigned long len
, unsigned long pgoff
, unsigned long flags
)
1689 vm_fault_t
filemap_fault(struct vm_fault
*vmf
)
1694 EXPORT_SYMBOL(filemap_fault
);
1696 void filemap_map_pages(struct vm_fault
*vmf
,
1697 pgoff_t start_pgoff
, pgoff_t end_pgoff
)
1701 EXPORT_SYMBOL(filemap_map_pages
);
1703 int __access_remote_vm(struct task_struct
*tsk
, struct mm_struct
*mm
,
1704 unsigned long addr
, void *buf
, int len
, unsigned int gup_flags
)
1706 struct vm_area_struct
*vma
;
1707 int write
= gup_flags
& FOLL_WRITE
;
1709 if (down_read_killable(&mm
->mmap_sem
))
1712 /* the access must start within one of the target process's mappings */
1713 vma
= find_vma(mm
, addr
);
1715 /* don't overrun this mapping */
1716 if (addr
+ len
>= vma
->vm_end
)
1717 len
= vma
->vm_end
- addr
;
1719 /* only read or write mappings where it is permitted */
1720 if (write
&& vma
->vm_flags
& VM_MAYWRITE
)
1721 copy_to_user_page(vma
, NULL
, addr
,
1722 (void *) addr
, buf
, len
);
1723 else if (!write
&& vma
->vm_flags
& VM_MAYREAD
)
1724 copy_from_user_page(vma
, NULL
, addr
,
1725 buf
, (void *) addr
, len
);
1732 up_read(&mm
->mmap_sem
);
1738 * access_remote_vm - access another process' address space
1739 * @mm: the mm_struct of the target address space
1740 * @addr: start address to access
1741 * @buf: source or destination buffer
1742 * @len: number of bytes to transfer
1743 * @gup_flags: flags modifying lookup behaviour
1745 * The caller must hold a reference on @mm.
1747 int access_remote_vm(struct mm_struct
*mm
, unsigned long addr
,
1748 void *buf
, int len
, unsigned int gup_flags
)
1750 return __access_remote_vm(NULL
, mm
, addr
, buf
, len
, gup_flags
);
1754 * Access another process' address space.
1755 * - source/target buffer must be kernel space
1757 int access_process_vm(struct task_struct
*tsk
, unsigned long addr
, void *buf
, int len
,
1758 unsigned int gup_flags
)
1760 struct mm_struct
*mm
;
1762 if (addr
+ len
< addr
)
1765 mm
= get_task_mm(tsk
);
1769 len
= __access_remote_vm(tsk
, mm
, addr
, buf
, len
, gup_flags
);
1774 EXPORT_SYMBOL_GPL(access_process_vm
);
1777 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
1778 * @inode: The inode to check
1779 * @size: The current filesize of the inode
1780 * @newsize: The proposed filesize of the inode
1782 * Check the shared mappings on an inode on behalf of a shrinking truncate to
1783 * make sure that that any outstanding VMAs aren't broken and then shrink the
1784 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
1785 * automatically grant mappings that are too large.
1787 int nommu_shrink_inode_mappings(struct inode
*inode
, size_t size
,
1790 struct vm_area_struct
*vma
;
1791 struct vm_region
*region
;
1793 size_t r_size
, r_top
;
1795 low
= newsize
>> PAGE_SHIFT
;
1796 high
= (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
1798 down_write(&nommu_region_sem
);
1799 i_mmap_lock_read(inode
->i_mapping
);
1801 /* search for VMAs that fall within the dead zone */
1802 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, low
, high
) {
1803 /* found one - only interested if it's shared out of the page
1805 if (vma
->vm_flags
& VM_SHARED
) {
1806 i_mmap_unlock_read(inode
->i_mapping
);
1807 up_write(&nommu_region_sem
);
1808 return -ETXTBSY
; /* not quite true, but near enough */
1812 /* reduce any regions that overlap the dead zone - if in existence,
1813 * these will be pointed to by VMAs that don't overlap the dead zone
1815 * we don't check for any regions that start beyond the EOF as there
1818 vma_interval_tree_foreach(vma
, &inode
->i_mapping
->i_mmap
, 0, ULONG_MAX
) {
1819 if (!(vma
->vm_flags
& VM_SHARED
))
1822 region
= vma
->vm_region
;
1823 r_size
= region
->vm_top
- region
->vm_start
;
1824 r_top
= (region
->vm_pgoff
<< PAGE_SHIFT
) + r_size
;
1826 if (r_top
> newsize
) {
1827 region
->vm_top
-= r_top
- newsize
;
1828 if (region
->vm_end
> region
->vm_top
)
1829 region
->vm_end
= region
->vm_top
;
1833 i_mmap_unlock_read(inode
->i_mapping
);
1834 up_write(&nommu_region_sem
);
1839 * Initialise sysctl_user_reserve_kbytes.
1841 * This is intended to prevent a user from starting a single memory hogging
1842 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
1845 * The default value is min(3% of free memory, 128MB)
1846 * 128MB is enough to recover with sshd/login, bash, and top/kill.
1848 static int __meminit
init_user_reserve(void)
1850 unsigned long free_kbytes
;
1852 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
1854 sysctl_user_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 17);
1857 subsys_initcall(init_user_reserve
);
1860 * Initialise sysctl_admin_reserve_kbytes.
1862 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
1863 * to log in and kill a memory hogging process.
1865 * Systems with more than 256MB will reserve 8MB, enough to recover
1866 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
1867 * only reserve 3% of free pages by default.
1869 static int __meminit
init_admin_reserve(void)
1871 unsigned long free_kbytes
;
1873 free_kbytes
= global_zone_page_state(NR_FREE_PAGES
) << (PAGE_SHIFT
- 10);
1875 sysctl_admin_reserve_kbytes
= min(free_kbytes
/ 32, 1UL << 13);
1878 subsys_initcall(init_admin_reserve
);