blob: 44265e00b701ebe5bc3327c8575f5181aa6a6f99
1 | /* |
2 | * linux/mm/nommu.c |
3 | * |
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). |
6 | * |
7 | * See Documentation/nommu-mmap.txt |
8 | * |
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> |
14 | */ |
15 | |
16 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
17 | |
18 | #include <linux/export.h> |
19 | #include <linux/mm.h> |
20 | #include <linux/vmacache.h> |
21 | #include <linux/mman.h> |
22 | #include <linux/swap.h> |
23 | #include <linux/file.h> |
24 | #include <linux/highmem.h> |
25 | #include <linux/pagemap.h> |
26 | #include <linux/slab.h> |
27 | #include <linux/vmalloc.h> |
28 | #include <linux/blkdev.h> |
29 | #include <linux/backing-dev.h> |
30 | #include <linux/compiler.h> |
31 | #include <linux/mount.h> |
32 | #include <linux/personality.h> |
33 | #include <linux/security.h> |
34 | #include <linux/syscalls.h> |
35 | #include <linux/audit.h> |
36 | #include <linux/printk.h> |
37 | |
38 | #include <asm/uaccess.h> |
39 | #include <asm/tlb.h> |
40 | #include <asm/tlbflush.h> |
41 | #include <asm/mmu_context.h> |
42 | #include "internal.h" |
43 | |
44 | void *high_memory; |
45 | EXPORT_SYMBOL(high_memory); |
46 | struct page *mem_map; |
47 | unsigned long max_mapnr; |
48 | EXPORT_SYMBOL(max_mapnr); |
49 | unsigned long highest_memmap_pfn; |
50 | int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; |
51 | int heap_stack_gap = 0; |
52 | |
53 | atomic_long_t mmap_pages_allocated; |
54 | |
55 | EXPORT_SYMBOL(mem_map); |
56 | |
57 | /* list of mapped, potentially shareable regions */ |
58 | static struct kmem_cache *vm_region_jar; |
59 | struct rb_root nommu_region_tree = RB_ROOT; |
60 | DECLARE_RWSEM(nommu_region_sem); |
61 | |
62 | const struct vm_operations_struct generic_file_vm_ops = { |
63 | }; |
64 | |
65 | /* |
66 | * Return the total memory allocated for this pointer, not |
67 | * just what the caller asked for. |
68 | * |
69 | * Doesn't have to be accurate, i.e. may have races. |
70 | */ |
71 | unsigned int kobjsize(const void *objp) |
72 | { |
73 | struct page *page; |
74 | |
75 | /* |
76 | * If the object we have should not have ksize performed on it, |
77 | * return size of 0 |
78 | */ |
79 | if (!objp || !virt_addr_valid(objp)) |
80 | return 0; |
81 | |
82 | page = virt_to_head_page(objp); |
83 | |
84 | /* |
85 | * If the allocator sets PageSlab, we know the pointer came from |
86 | * kmalloc(). |
87 | */ |
88 | if (PageSlab(page)) |
89 | return ksize(objp); |
90 | |
91 | /* |
92 | * If it's not a compound page, see if we have a matching VMA |
93 | * region. This test is intentionally done in reverse order, |
94 | * so if there's no VMA, we still fall through and hand back |
95 | * PAGE_SIZE for 0-order pages. |
96 | */ |
97 | if (!PageCompound(page)) { |
98 | struct vm_area_struct *vma; |
99 | |
100 | vma = find_vma(current->mm, (unsigned long)objp); |
101 | if (vma) |
102 | return vma->vm_end - vma->vm_start; |
103 | } |
104 | |
105 | /* |
106 | * The ksize() function is only guaranteed to work for pointers |
107 | * returned by kmalloc(). So handle arbitrary pointers here. |
108 | */ |
109 | return PAGE_SIZE << compound_order(page); |
110 | } |
111 | |
112 | static long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
113 | unsigned long start, unsigned long nr_pages, |
114 | unsigned int foll_flags, struct page **pages, |
115 | struct vm_area_struct **vmas, int *nonblocking) |
116 | { |
117 | struct vm_area_struct *vma; |
118 | unsigned long vm_flags; |
119 | int i; |
120 | |
121 | /* calculate required read or write permissions. |
122 | * If FOLL_FORCE is set, we only require the "MAY" flags. |
123 | */ |
124 | vm_flags = (foll_flags & FOLL_WRITE) ? |
125 | (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); |
126 | vm_flags &= (foll_flags & FOLL_FORCE) ? |
127 | (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); |
128 | |
129 | for (i = 0; i < nr_pages; i++) { |
130 | vma = find_vma(mm, start); |
131 | if (!vma) |
132 | goto finish_or_fault; |
133 | |
134 | /* protect what we can, including chardevs */ |
135 | if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || |
136 | !(vm_flags & vma->vm_flags)) |
137 | goto finish_or_fault; |
138 | |
139 | if (pages) { |
140 | pages[i] = virt_to_page(start); |
141 | if (pages[i]) |
142 | get_page(pages[i]); |
143 | } |
144 | if (vmas) |
145 | vmas[i] = vma; |
146 | start = (start + PAGE_SIZE) & PAGE_MASK; |
147 | } |
148 | |
149 | return i; |
150 | |
151 | finish_or_fault: |
152 | return i ? : -EFAULT; |
153 | } |
154 | |
155 | /* |
156 | * get a list of pages in an address range belonging to the specified process |
157 | * and indicate the VMA that covers each page |
158 | * - this is potentially dodgy as we may end incrementing the page count of a |
159 | * slab page or a secondary page from a compound page |
160 | * - don't permit access to VMAs that don't support it, such as I/O mappings |
161 | */ |
162 | long get_user_pages(unsigned long start, unsigned long nr_pages, |
163 | unsigned int gup_flags, struct page **pages, |
164 | struct vm_area_struct **vmas) |
165 | { |
166 | return __get_user_pages(current, current->mm, start, nr_pages, |
167 | gup_flags, pages, vmas, NULL); |
168 | } |
169 | EXPORT_SYMBOL(get_user_pages); |
170 | |
171 | long get_user_pages_locked(unsigned long start, unsigned long nr_pages, |
172 | unsigned int gup_flags, struct page **pages, |
173 | int *locked) |
174 | { |
175 | return get_user_pages(start, nr_pages, gup_flags, pages, NULL); |
176 | } |
177 | EXPORT_SYMBOL(get_user_pages_locked); |
178 | |
179 | long __get_user_pages_unlocked(struct task_struct *tsk, struct mm_struct *mm, |
180 | unsigned long start, unsigned long nr_pages, |
181 | struct page **pages, unsigned int gup_flags) |
182 | { |
183 | long ret; |
184 | down_read(&mm->mmap_sem); |
185 | ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages, |
186 | NULL, NULL); |
187 | up_read(&mm->mmap_sem); |
188 | return ret; |
189 | } |
190 | EXPORT_SYMBOL(__get_user_pages_unlocked); |
191 | |
192 | long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages, |
193 | struct page **pages, unsigned int gup_flags) |
194 | { |
195 | return __get_user_pages_unlocked(current, current->mm, start, nr_pages, |
196 | pages, gup_flags); |
197 | } |
198 | EXPORT_SYMBOL(get_user_pages_unlocked); |
199 | |
200 | /** |
201 | * follow_pfn - look up PFN at a user virtual address |
202 | * @vma: memory mapping |
203 | * @address: user virtual address |
204 | * @pfn: location to store found PFN |
205 | * |
206 | * Only IO mappings and raw PFN mappings are allowed. |
207 | * |
208 | * Returns zero and the pfn at @pfn on success, -ve otherwise. |
209 | */ |
210 | int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
211 | unsigned long *pfn) |
212 | { |
213 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
214 | return -EINVAL; |
215 | |
216 | *pfn = address >> PAGE_SHIFT; |
217 | return 0; |
218 | } |
219 | EXPORT_SYMBOL(follow_pfn); |
220 | |
221 | LIST_HEAD(vmap_area_list); |
222 | |
223 | void vfree(const void *addr) |
224 | { |
225 | kfree(addr); |
226 | } |
227 | EXPORT_SYMBOL(vfree); |
228 | |
229 | void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) |
230 | { |
231 | /* |
232 | * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() |
233 | * returns only a logical address. |
234 | */ |
235 | return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); |
236 | } |
237 | EXPORT_SYMBOL(__vmalloc); |
238 | |
239 | void *vmalloc_user(unsigned long size) |
240 | { |
241 | void *ret; |
242 | |
243 | ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, |
244 | PAGE_KERNEL); |
245 | if (ret) { |
246 | struct vm_area_struct *vma; |
247 | |
248 | down_write(¤t->mm->mmap_sem); |
249 | vma = find_vma(current->mm, (unsigned long)ret); |
250 | if (vma) |
251 | vma->vm_flags |= VM_USERMAP; |
252 | up_write(¤t->mm->mmap_sem); |
253 | } |
254 | |
255 | return ret; |
256 | } |
257 | EXPORT_SYMBOL(vmalloc_user); |
258 | |
259 | struct page *vmalloc_to_page(const void *addr) |
260 | { |
261 | return virt_to_page(addr); |
262 | } |
263 | EXPORT_SYMBOL(vmalloc_to_page); |
264 | |
265 | unsigned long vmalloc_to_pfn(const void *addr) |
266 | { |
267 | return page_to_pfn(virt_to_page(addr)); |
268 | } |
269 | EXPORT_SYMBOL(vmalloc_to_pfn); |
270 | |
271 | long vread(char *buf, char *addr, unsigned long count) |
272 | { |
273 | /* Don't allow overflow */ |
274 | if ((unsigned long) buf + count < count) |
275 | count = -(unsigned long) buf; |
276 | |
277 | memcpy(buf, addr, count); |
278 | return count; |
279 | } |
280 | |
281 | long vwrite(char *buf, char *addr, unsigned long count) |
282 | { |
283 | /* Don't allow overflow */ |
284 | if ((unsigned long) addr + count < count) |
285 | count = -(unsigned long) addr; |
286 | |
287 | memcpy(addr, buf, count); |
288 | return count; |
289 | } |
290 | |
291 | /* |
292 | * vmalloc - allocate virtually contiguous memory |
293 | * |
294 | * @size: allocation size |
295 | * |
296 | * Allocate enough pages to cover @size from the page level |
297 | * allocator and map them into contiguous kernel virtual space. |
298 | * |
299 | * For tight control over page level allocator and protection flags |
300 | * use __vmalloc() instead. |
301 | */ |
302 | void *vmalloc(unsigned long size) |
303 | { |
304 | return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); |
305 | } |
306 | EXPORT_SYMBOL(vmalloc); |
307 | |
308 | /* |
309 | * vzalloc - allocate virtually contiguous memory with zero fill |
310 | * |
311 | * @size: allocation size |
312 | * |
313 | * Allocate enough pages to cover @size from the page level |
314 | * allocator and map them into contiguous kernel virtual space. |
315 | * The memory allocated is set to zero. |
316 | * |
317 | * For tight control over page level allocator and protection flags |
318 | * use __vmalloc() instead. |
319 | */ |
320 | void *vzalloc(unsigned long size) |
321 | { |
322 | return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, |
323 | PAGE_KERNEL); |
324 | } |
325 | EXPORT_SYMBOL(vzalloc); |
326 | |
327 | /** |
328 | * vmalloc_node - allocate memory on a specific node |
329 | * @size: allocation size |
330 | * @node: numa node |
331 | * |
332 | * Allocate enough pages to cover @size from the page level |
333 | * allocator and map them into contiguous kernel virtual space. |
334 | * |
335 | * For tight control over page level allocator and protection flags |
336 | * use __vmalloc() instead. |
337 | */ |
338 | void *vmalloc_node(unsigned long size, int node) |
339 | { |
340 | return vmalloc(size); |
341 | } |
342 | EXPORT_SYMBOL(vmalloc_node); |
343 | |
344 | /** |
345 | * vzalloc_node - allocate memory on a specific node with zero fill |
346 | * @size: allocation size |
347 | * @node: numa node |
348 | * |
349 | * Allocate enough pages to cover @size from the page level |
350 | * allocator and map them into contiguous kernel virtual space. |
351 | * The memory allocated is set to zero. |
352 | * |
353 | * For tight control over page level allocator and protection flags |
354 | * use __vmalloc() instead. |
355 | */ |
356 | void *vzalloc_node(unsigned long size, int node) |
357 | { |
358 | return vzalloc(size); |
359 | } |
360 | EXPORT_SYMBOL(vzalloc_node); |
361 | |
362 | #ifndef PAGE_KERNEL_EXEC |
363 | # define PAGE_KERNEL_EXEC PAGE_KERNEL |
364 | #endif |
365 | |
366 | /** |
367 | * vmalloc_exec - allocate virtually contiguous, executable memory |
368 | * @size: allocation size |
369 | * |
370 | * Kernel-internal function to allocate enough pages to cover @size |
371 | * the page level allocator and map them into contiguous and |
372 | * executable kernel virtual space. |
373 | * |
374 | * For tight control over page level allocator and protection flags |
375 | * use __vmalloc() instead. |
376 | */ |
377 | |
378 | void *vmalloc_exec(unsigned long size) |
379 | { |
380 | return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); |
381 | } |
382 | |
383 | /** |
384 | * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) |
385 | * @size: allocation size |
386 | * |
387 | * Allocate enough 32bit PA addressable pages to cover @size from the |
388 | * page level allocator and map them into contiguous kernel virtual space. |
389 | */ |
390 | void *vmalloc_32(unsigned long size) |
391 | { |
392 | return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); |
393 | } |
394 | EXPORT_SYMBOL(vmalloc_32); |
395 | |
396 | /** |
397 | * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory |
398 | * @size: allocation size |
399 | * |
400 | * The resulting memory area is 32bit addressable and zeroed so it can be |
401 | * mapped to userspace without leaking data. |
402 | * |
403 | * VM_USERMAP is set on the corresponding VMA so that subsequent calls to |
404 | * remap_vmalloc_range() are permissible. |
405 | */ |
406 | void *vmalloc_32_user(unsigned long size) |
407 | { |
408 | /* |
409 | * We'll have to sort out the ZONE_DMA bits for 64-bit, |
410 | * but for now this can simply use vmalloc_user() directly. |
411 | */ |
412 | return vmalloc_user(size); |
413 | } |
414 | EXPORT_SYMBOL(vmalloc_32_user); |
415 | |
416 | void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) |
417 | { |
418 | BUG(); |
419 | return NULL; |
420 | } |
421 | EXPORT_SYMBOL(vmap); |
422 | |
423 | void vunmap(const void *addr) |
424 | { |
425 | BUG(); |
426 | } |
427 | EXPORT_SYMBOL(vunmap); |
428 | |
429 | void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) |
430 | { |
431 | BUG(); |
432 | return NULL; |
433 | } |
434 | EXPORT_SYMBOL(vm_map_ram); |
435 | |
436 | void vm_unmap_ram(const void *mem, unsigned int count) |
437 | { |
438 | BUG(); |
439 | } |
440 | EXPORT_SYMBOL(vm_unmap_ram); |
441 | |
442 | void vm_unmap_aliases(void) |
443 | { |
444 | } |
445 | EXPORT_SYMBOL_GPL(vm_unmap_aliases); |
446 | |
447 | /* |
448 | * Implement a stub for vmalloc_sync_all() if the architecture chose not to |
449 | * have one. |
450 | */ |
451 | void __weak vmalloc_sync_all(void) |
452 | { |
453 | } |
454 | |
455 | /** |
456 | * alloc_vm_area - allocate a range of kernel address space |
457 | * @size: size of the area |
458 | * |
459 | * Returns: NULL on failure, vm_struct on success |
460 | * |
461 | * This function reserves a range of kernel address space, and |
462 | * allocates pagetables to map that range. No actual mappings |
463 | * are created. If the kernel address space is not shared |
464 | * between processes, it syncs the pagetable across all |
465 | * processes. |
466 | */ |
467 | struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes) |
468 | { |
469 | BUG(); |
470 | return NULL; |
471 | } |
472 | EXPORT_SYMBOL_GPL(alloc_vm_area); |
473 | |
474 | void free_vm_area(struct vm_struct *area) |
475 | { |
476 | BUG(); |
477 | } |
478 | EXPORT_SYMBOL_GPL(free_vm_area); |
479 | |
480 | int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
481 | struct page *page) |
482 | { |
483 | return -EINVAL; |
484 | } |
485 | EXPORT_SYMBOL(vm_insert_page); |
486 | |
487 | /* |
488 | * sys_brk() for the most part doesn't need the global kernel |
489 | * lock, except when an application is doing something nasty |
490 | * like trying to un-brk an area that has already been mapped |
491 | * to a regular file. in this case, the unmapping will need |
492 | * to invoke file system routines that need the global lock. |
493 | */ |
494 | SYSCALL_DEFINE1(brk, unsigned long, brk) |
495 | { |
496 | struct mm_struct *mm = current->mm; |
497 | |
498 | if (brk < mm->start_brk || brk > mm->context.end_brk) |
499 | return mm->brk; |
500 | |
501 | if (mm->brk == brk) |
502 | return mm->brk; |
503 | |
504 | /* |
505 | * Always allow shrinking brk |
506 | */ |
507 | if (brk <= mm->brk) { |
508 | mm->brk = brk; |
509 | return brk; |
510 | } |
511 | |
512 | /* |
513 | * Ok, looks good - let it rip. |
514 | */ |
515 | flush_icache_range(mm->brk, brk); |
516 | return mm->brk = brk; |
517 | } |
518 | |
519 | /* |
520 | * initialise the VMA and region record slabs |
521 | */ |
522 | void __init mmap_init(void) |
523 | { |
524 | int ret; |
525 | |
526 | ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); |
527 | VM_BUG_ON(ret); |
528 | vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT); |
529 | } |
530 | |
531 | /* |
532 | * validate the region tree |
533 | * - the caller must hold the region lock |
534 | */ |
535 | #ifdef CONFIG_DEBUG_NOMMU_REGIONS |
536 | static noinline void validate_nommu_regions(void) |
537 | { |
538 | struct vm_region *region, *last; |
539 | struct rb_node *p, *lastp; |
540 | |
541 | lastp = rb_first(&nommu_region_tree); |
542 | if (!lastp) |
543 | return; |
544 | |
545 | last = rb_entry(lastp, struct vm_region, vm_rb); |
546 | BUG_ON(last->vm_end <= last->vm_start); |
547 | BUG_ON(last->vm_top < last->vm_end); |
548 | |
549 | while ((p = rb_next(lastp))) { |
550 | region = rb_entry(p, struct vm_region, vm_rb); |
551 | last = rb_entry(lastp, struct vm_region, vm_rb); |
552 | |
553 | BUG_ON(region->vm_end <= region->vm_start); |
554 | BUG_ON(region->vm_top < region->vm_end); |
555 | BUG_ON(region->vm_start < last->vm_top); |
556 | |
557 | lastp = p; |
558 | } |
559 | } |
560 | #else |
561 | static void validate_nommu_regions(void) |
562 | { |
563 | } |
564 | #endif |
565 | |
566 | /* |
567 | * add a region into the global tree |
568 | */ |
569 | static void add_nommu_region(struct vm_region *region) |
570 | { |
571 | struct vm_region *pregion; |
572 | struct rb_node **p, *parent; |
573 | |
574 | validate_nommu_regions(); |
575 | |
576 | parent = NULL; |
577 | p = &nommu_region_tree.rb_node; |
578 | while (*p) { |
579 | parent = *p; |
580 | pregion = rb_entry(parent, struct vm_region, vm_rb); |
581 | if (region->vm_start < pregion->vm_start) |
582 | p = &(*p)->rb_left; |
583 | else if (region->vm_start > pregion->vm_start) |
584 | p = &(*p)->rb_right; |
585 | else if (pregion == region) |
586 | return; |
587 | else |
588 | BUG(); |
589 | } |
590 | |
591 | rb_link_node(®ion->vm_rb, parent, p); |
592 | rb_insert_color(®ion->vm_rb, &nommu_region_tree); |
593 | |
594 | validate_nommu_regions(); |
595 | } |
596 | |
597 | /* |
598 | * delete a region from the global tree |
599 | */ |
600 | static void delete_nommu_region(struct vm_region *region) |
601 | { |
602 | BUG_ON(!nommu_region_tree.rb_node); |
603 | |
604 | validate_nommu_regions(); |
605 | rb_erase(®ion->vm_rb, &nommu_region_tree); |
606 | validate_nommu_regions(); |
607 | } |
608 | |
609 | /* |
610 | * free a contiguous series of pages |
611 | */ |
612 | static void free_page_series(unsigned long from, unsigned long to) |
613 | { |
614 | for (; from < to; from += PAGE_SIZE) { |
615 | struct page *page = virt_to_page(from); |
616 | |
617 | atomic_long_dec(&mmap_pages_allocated); |
618 | put_page(page); |
619 | } |
620 | } |
621 | |
622 | /* |
623 | * release a reference to a region |
624 | * - the caller must hold the region semaphore for writing, which this releases |
625 | * - the region may not have been added to the tree yet, in which case vm_top |
626 | * will equal vm_start |
627 | */ |
628 | static void __put_nommu_region(struct vm_region *region) |
629 | __releases(nommu_region_sem) |
630 | { |
631 | BUG_ON(!nommu_region_tree.rb_node); |
632 | |
633 | if (--region->vm_usage == 0) { |
634 | if (region->vm_top > region->vm_start) |
635 | delete_nommu_region(region); |
636 | up_write(&nommu_region_sem); |
637 | |
638 | if (region->vm_file) |
639 | fput(region->vm_file); |
640 | |
641 | /* IO memory and memory shared directly out of the pagecache |
642 | * from ramfs/tmpfs mustn't be released here */ |
643 | if (region->vm_flags & VM_MAPPED_COPY) |
644 | free_page_series(region->vm_start, region->vm_top); |
645 | kmem_cache_free(vm_region_jar, region); |
646 | } else { |
647 | up_write(&nommu_region_sem); |
648 | } |
649 | } |
650 | |
651 | /* |
652 | * release a reference to a region |
653 | */ |
654 | static void put_nommu_region(struct vm_region *region) |
655 | { |
656 | down_write(&nommu_region_sem); |
657 | __put_nommu_region(region); |
658 | } |
659 | |
660 | /* |
661 | * update protection on a vma |
662 | */ |
663 | static void protect_vma(struct vm_area_struct *vma, unsigned long flags) |
664 | { |
665 | #ifdef CONFIG_MPU |
666 | struct mm_struct *mm = vma->vm_mm; |
667 | long start = vma->vm_start & PAGE_MASK; |
668 | while (start < vma->vm_end) { |
669 | protect_page(mm, start, flags); |
670 | start += PAGE_SIZE; |
671 | } |
672 | update_protections(mm); |
673 | #endif |
674 | } |
675 | |
676 | /* |
677 | * add a VMA into a process's mm_struct in the appropriate place in the list |
678 | * and tree and add to the address space's page tree also if not an anonymous |
679 | * page |
680 | * - should be called with mm->mmap_sem held writelocked |
681 | */ |
682 | static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) |
683 | { |
684 | struct vm_area_struct *pvma, *prev; |
685 | struct address_space *mapping; |
686 | struct rb_node **p, *parent, *rb_prev; |
687 | |
688 | BUG_ON(!vma->vm_region); |
689 | |
690 | mm->map_count++; |
691 | vma->vm_mm = mm; |
692 | |
693 | protect_vma(vma, vma->vm_flags); |
694 | |
695 | /* add the VMA to the mapping */ |
696 | if (vma->vm_file) { |
697 | mapping = vma->vm_file->f_mapping; |
698 | |
699 | i_mmap_lock_write(mapping); |
700 | flush_dcache_mmap_lock(mapping); |
701 | vma_interval_tree_insert(vma, &mapping->i_mmap); |
702 | flush_dcache_mmap_unlock(mapping); |
703 | i_mmap_unlock_write(mapping); |
704 | } |
705 | |
706 | /* add the VMA to the tree */ |
707 | parent = rb_prev = NULL; |
708 | p = &mm->mm_rb.rb_node; |
709 | while (*p) { |
710 | parent = *p; |
711 | pvma = rb_entry(parent, struct vm_area_struct, vm_rb); |
712 | |
713 | /* sort by: start addr, end addr, VMA struct addr in that order |
714 | * (the latter is necessary as we may get identical VMAs) */ |
715 | if (vma->vm_start < pvma->vm_start) |
716 | p = &(*p)->rb_left; |
717 | else if (vma->vm_start > pvma->vm_start) { |
718 | rb_prev = parent; |
719 | p = &(*p)->rb_right; |
720 | } else if (vma->vm_end < pvma->vm_end) |
721 | p = &(*p)->rb_left; |
722 | else if (vma->vm_end > pvma->vm_end) { |
723 | rb_prev = parent; |
724 | p = &(*p)->rb_right; |
725 | } else if (vma < pvma) |
726 | p = &(*p)->rb_left; |
727 | else if (vma > pvma) { |
728 | rb_prev = parent; |
729 | p = &(*p)->rb_right; |
730 | } else |
731 | BUG(); |
732 | } |
733 | |
734 | rb_link_node(&vma->vm_rb, parent, p); |
735 | rb_insert_color(&vma->vm_rb, &mm->mm_rb); |
736 | |
737 | /* add VMA to the VMA list also */ |
738 | prev = NULL; |
739 | if (rb_prev) |
740 | prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); |
741 | |
742 | __vma_link_list(mm, vma, prev, parent); |
743 | } |
744 | |
745 | /* |
746 | * delete a VMA from its owning mm_struct and address space |
747 | */ |
748 | static void delete_vma_from_mm(struct vm_area_struct *vma) |
749 | { |
750 | int i; |
751 | struct address_space *mapping; |
752 | struct mm_struct *mm = vma->vm_mm; |
753 | struct task_struct *curr = current; |
754 | |
755 | protect_vma(vma, 0); |
756 | |
757 | mm->map_count--; |
758 | for (i = 0; i < VMACACHE_SIZE; i++) { |
759 | /* if the vma is cached, invalidate the entire cache */ |
760 | if (curr->vmacache[i] == vma) { |
761 | vmacache_invalidate(mm); |
762 | break; |
763 | } |
764 | } |
765 | |
766 | /* remove the VMA from the mapping */ |
767 | if (vma->vm_file) { |
768 | mapping = vma->vm_file->f_mapping; |
769 | |
770 | i_mmap_lock_write(mapping); |
771 | flush_dcache_mmap_lock(mapping); |
772 | vma_interval_tree_remove(vma, &mapping->i_mmap); |
773 | flush_dcache_mmap_unlock(mapping); |
774 | i_mmap_unlock_write(mapping); |
775 | } |
776 | |
777 | /* remove from the MM's tree and list */ |
778 | rb_erase(&vma->vm_rb, &mm->mm_rb); |
779 | |
780 | if (vma->vm_prev) |
781 | vma->vm_prev->vm_next = vma->vm_next; |
782 | else |
783 | mm->mmap = vma->vm_next; |
784 | |
785 | if (vma->vm_next) |
786 | vma->vm_next->vm_prev = vma->vm_prev; |
787 | } |
788 | |
789 | /* |
790 | * destroy a VMA record |
791 | */ |
792 | static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) |
793 | { |
794 | if (vma->vm_ops && vma->vm_ops->close) |
795 | vma->vm_ops->close(vma); |
796 | if (vma->vm_file) |
797 | fput(vma->vm_file); |
798 | put_nommu_region(vma->vm_region); |
799 | kmem_cache_free(vm_area_cachep, vma); |
800 | } |
801 | |
802 | /* |
803 | * look up the first VMA in which addr resides, NULL if none |
804 | * - should be called with mm->mmap_sem at least held readlocked |
805 | */ |
806 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
807 | { |
808 | struct vm_area_struct *vma; |
809 | |
810 | /* check the cache first */ |
811 | vma = vmacache_find(mm, addr); |
812 | if (likely(vma)) |
813 | return vma; |
814 | |
815 | /* trawl the list (there may be multiple mappings in which addr |
816 | * resides) */ |
817 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
818 | if (vma->vm_start > addr) |
819 | return NULL; |
820 | if (vma->vm_end > addr) { |
821 | vmacache_update(addr, vma); |
822 | return vma; |
823 | } |
824 | } |
825 | |
826 | return NULL; |
827 | } |
828 | EXPORT_SYMBOL(find_vma); |
829 | |
830 | /* |
831 | * find a VMA |
832 | * - we don't extend stack VMAs under NOMMU conditions |
833 | */ |
834 | struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) |
835 | { |
836 | return find_vma(mm, addr); |
837 | } |
838 | |
839 | /* |
840 | * expand a stack to a given address |
841 | * - not supported under NOMMU conditions |
842 | */ |
843 | int expand_stack(struct vm_area_struct *vma, unsigned long address) |
844 | { |
845 | return -ENOMEM; |
846 | } |
847 | |
848 | /* |
849 | * look up the first VMA exactly that exactly matches addr |
850 | * - should be called with mm->mmap_sem at least held readlocked |
851 | */ |
852 | static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, |
853 | unsigned long addr, |
854 | unsigned long len) |
855 | { |
856 | struct vm_area_struct *vma; |
857 | unsigned long end = addr + len; |
858 | |
859 | /* check the cache first */ |
860 | vma = vmacache_find_exact(mm, addr, end); |
861 | if (vma) |
862 | return vma; |
863 | |
864 | /* trawl the list (there may be multiple mappings in which addr |
865 | * resides) */ |
866 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
867 | if (vma->vm_start < addr) |
868 | continue; |
869 | if (vma->vm_start > addr) |
870 | return NULL; |
871 | if (vma->vm_end == end) { |
872 | vmacache_update(addr, vma); |
873 | return vma; |
874 | } |
875 | } |
876 | |
877 | return NULL; |
878 | } |
879 | |
880 | /* |
881 | * determine whether a mapping should be permitted and, if so, what sort of |
882 | * mapping we're capable of supporting |
883 | */ |
884 | static int validate_mmap_request(struct file *file, |
885 | unsigned long addr, |
886 | unsigned long len, |
887 | unsigned long prot, |
888 | unsigned long flags, |
889 | unsigned long pgoff, |
890 | unsigned long *_capabilities) |
891 | { |
892 | unsigned long capabilities, rlen; |
893 | int ret; |
894 | |
895 | /* do the simple checks first */ |
896 | if (flags & MAP_FIXED) |
897 | return -EINVAL; |
898 | |
899 | if ((flags & MAP_TYPE) != MAP_PRIVATE && |
900 | (flags & MAP_TYPE) != MAP_SHARED) |
901 | return -EINVAL; |
902 | |
903 | if (!len) |
904 | return -EINVAL; |
905 | |
906 | /* Careful about overflows.. */ |
907 | rlen = PAGE_ALIGN(len); |
908 | if (!rlen || rlen > TASK_SIZE) |
909 | return -ENOMEM; |
910 | |
911 | /* offset overflow? */ |
912 | if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) |
913 | return -EOVERFLOW; |
914 | |
915 | if (file) { |
916 | /* files must support mmap */ |
917 | if (!file->f_op->mmap) |
918 | return -ENODEV; |
919 | |
920 | /* work out if what we've got could possibly be shared |
921 | * - we support chardevs that provide their own "memory" |
922 | * - we support files/blockdevs that are memory backed |
923 | */ |
924 | if (file->f_op->mmap_capabilities) { |
925 | capabilities = file->f_op->mmap_capabilities(file); |
926 | } else { |
927 | /* no explicit capabilities set, so assume some |
928 | * defaults */ |
929 | switch (file_inode(file)->i_mode & S_IFMT) { |
930 | case S_IFREG: |
931 | case S_IFBLK: |
932 | capabilities = NOMMU_MAP_COPY; |
933 | break; |
934 | |
935 | case S_IFCHR: |
936 | capabilities = |
937 | NOMMU_MAP_DIRECT | |
938 | NOMMU_MAP_READ | |
939 | NOMMU_MAP_WRITE; |
940 | break; |
941 | |
942 | default: |
943 | return -EINVAL; |
944 | } |
945 | } |
946 | |
947 | /* eliminate any capabilities that we can't support on this |
948 | * device */ |
949 | if (!file->f_op->get_unmapped_area) |
950 | capabilities &= ~NOMMU_MAP_DIRECT; |
951 | if (!(file->f_mode & FMODE_CAN_READ)) |
952 | capabilities &= ~NOMMU_MAP_COPY; |
953 | |
954 | /* The file shall have been opened with read permission. */ |
955 | if (!(file->f_mode & FMODE_READ)) |
956 | return -EACCES; |
957 | |
958 | if (flags & MAP_SHARED) { |
959 | /* do checks for writing, appending and locking */ |
960 | if ((prot & PROT_WRITE) && |
961 | !(file->f_mode & FMODE_WRITE)) |
962 | return -EACCES; |
963 | |
964 | if (IS_APPEND(file_inode(file)) && |
965 | (file->f_mode & FMODE_WRITE)) |
966 | return -EACCES; |
967 | |
968 | if (locks_verify_locked(file)) |
969 | return -EAGAIN; |
970 | |
971 | if (!(capabilities & NOMMU_MAP_DIRECT)) |
972 | return -ENODEV; |
973 | |
974 | /* we mustn't privatise shared mappings */ |
975 | capabilities &= ~NOMMU_MAP_COPY; |
976 | } else { |
977 | /* we're going to read the file into private memory we |
978 | * allocate */ |
979 | if (!(capabilities & NOMMU_MAP_COPY)) |
980 | return -ENODEV; |
981 | |
982 | /* we don't permit a private writable mapping to be |
983 | * shared with the backing device */ |
984 | if (prot & PROT_WRITE) |
985 | capabilities &= ~NOMMU_MAP_DIRECT; |
986 | } |
987 | |
988 | if (capabilities & NOMMU_MAP_DIRECT) { |
989 | if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) || |
990 | ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) || |
991 | ((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC)) |
992 | ) { |
993 | capabilities &= ~NOMMU_MAP_DIRECT; |
994 | if (flags & MAP_SHARED) { |
995 | pr_warn("MAP_SHARED not completely supported on !MMU\n"); |
996 | return -EINVAL; |
997 | } |
998 | } |
999 | } |
1000 | |
1001 | /* handle executable mappings and implied executable |
1002 | * mappings */ |
1003 | if (path_noexec(&file->f_path)) { |
1004 | if (prot & PROT_EXEC) |
1005 | return -EPERM; |
1006 | } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { |
1007 | /* handle implication of PROT_EXEC by PROT_READ */ |
1008 | if (current->personality & READ_IMPLIES_EXEC) { |
1009 | if (capabilities & NOMMU_MAP_EXEC) |
1010 | prot |= PROT_EXEC; |
1011 | } |
1012 | } else if ((prot & PROT_READ) && |
1013 | (prot & PROT_EXEC) && |
1014 | !(capabilities & NOMMU_MAP_EXEC) |
1015 | ) { |
1016 | /* backing file is not executable, try to copy */ |
1017 | capabilities &= ~NOMMU_MAP_DIRECT; |
1018 | } |
1019 | } else { |
1020 | /* anonymous mappings are always memory backed and can be |
1021 | * privately mapped |
1022 | */ |
1023 | capabilities = NOMMU_MAP_COPY; |
1024 | |
1025 | /* handle PROT_EXEC implication by PROT_READ */ |
1026 | if ((prot & PROT_READ) && |
1027 | (current->personality & READ_IMPLIES_EXEC)) |
1028 | prot |= PROT_EXEC; |
1029 | } |
1030 | |
1031 | /* allow the security API to have its say */ |
1032 | ret = security_mmap_addr(addr); |
1033 | if (ret < 0) |
1034 | return ret; |
1035 | |
1036 | /* looks okay */ |
1037 | *_capabilities = capabilities; |
1038 | return 0; |
1039 | } |
1040 | |
1041 | /* |
1042 | * we've determined that we can make the mapping, now translate what we |
1043 | * now know into VMA flags |
1044 | */ |
1045 | static unsigned long determine_vm_flags(struct file *file, |
1046 | unsigned long prot, |
1047 | unsigned long flags, |
1048 | unsigned long capabilities) |
1049 | { |
1050 | unsigned long vm_flags; |
1051 | |
1052 | vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags); |
1053 | /* vm_flags |= mm->def_flags; */ |
1054 | |
1055 | if (!(capabilities & NOMMU_MAP_DIRECT)) { |
1056 | /* attempt to share read-only copies of mapped file chunks */ |
1057 | vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
1058 | if (file && !(prot & PROT_WRITE)) |
1059 | vm_flags |= VM_MAYSHARE; |
1060 | } else { |
1061 | /* overlay a shareable mapping on the backing device or inode |
1062 | * if possible - used for chardevs, ramfs/tmpfs/shmfs and |
1063 | * romfs/cramfs */ |
1064 | vm_flags |= VM_MAYSHARE | (capabilities & NOMMU_VMFLAGS); |
1065 | if (flags & MAP_SHARED) |
1066 | vm_flags |= VM_SHARED; |
1067 | } |
1068 | |
1069 | /* refuse to let anyone share private mappings with this process if |
1070 | * it's being traced - otherwise breakpoints set in it may interfere |
1071 | * with another untraced process |
1072 | */ |
1073 | if ((flags & MAP_PRIVATE) && current->ptrace) |
1074 | vm_flags &= ~VM_MAYSHARE; |
1075 | |
1076 | return vm_flags; |
1077 | } |
1078 | |
1079 | /* |
1080 | * set up a shared mapping on a file (the driver or filesystem provides and |
1081 | * pins the storage) |
1082 | */ |
1083 | static int do_mmap_shared_file(struct vm_area_struct *vma) |
1084 | { |
1085 | int ret; |
1086 | |
1087 | ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); |
1088 | if (ret == 0) { |
1089 | vma->vm_region->vm_top = vma->vm_region->vm_end; |
1090 | return 0; |
1091 | } |
1092 | if (ret != -ENOSYS) |
1093 | return ret; |
1094 | |
1095 | /* getting -ENOSYS indicates that direct mmap isn't possible (as |
1096 | * opposed to tried but failed) so we can only give a suitable error as |
1097 | * it's not possible to make a private copy if MAP_SHARED was given */ |
1098 | return -ENODEV; |
1099 | } |
1100 | |
1101 | /* |
1102 | * set up a private mapping or an anonymous shared mapping |
1103 | */ |
1104 | static int do_mmap_private(struct vm_area_struct *vma, |
1105 | struct vm_region *region, |
1106 | unsigned long len, |
1107 | unsigned long capabilities) |
1108 | { |
1109 | unsigned long total, point; |
1110 | void *base; |
1111 | int ret, order; |
1112 | |
1113 | /* invoke the file's mapping function so that it can keep track of |
1114 | * shared mappings on devices or memory |
1115 | * - VM_MAYSHARE will be set if it may attempt to share |
1116 | */ |
1117 | if (capabilities & NOMMU_MAP_DIRECT) { |
1118 | ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); |
1119 | if (ret == 0) { |
1120 | /* shouldn't return success if we're not sharing */ |
1121 | BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); |
1122 | vma->vm_region->vm_top = vma->vm_region->vm_end; |
1123 | return 0; |
1124 | } |
1125 | if (ret != -ENOSYS) |
1126 | return ret; |
1127 | |
1128 | /* getting an ENOSYS error indicates that direct mmap isn't |
1129 | * possible (as opposed to tried but failed) so we'll try to |
1130 | * make a private copy of the data and map that instead */ |
1131 | } |
1132 | |
1133 | |
1134 | /* allocate some memory to hold the mapping |
1135 | * - note that this may not return a page-aligned address if the object |
1136 | * we're allocating is smaller than a page |
1137 | */ |
1138 | order = get_order(len); |
1139 | total = 1 << order; |
1140 | point = len >> PAGE_SHIFT; |
1141 | |
1142 | /* we don't want to allocate a power-of-2 sized page set */ |
1143 | if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) |
1144 | total = point; |
1145 | |
1146 | base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL); |
1147 | if (!base) |
1148 | goto enomem; |
1149 | |
1150 | atomic_long_add(total, &mmap_pages_allocated); |
1151 | |
1152 | region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; |
1153 | region->vm_start = (unsigned long) base; |
1154 | region->vm_end = region->vm_start + len; |
1155 | region->vm_top = region->vm_start + (total << PAGE_SHIFT); |
1156 | |
1157 | vma->vm_start = region->vm_start; |
1158 | vma->vm_end = region->vm_start + len; |
1159 | |
1160 | if (vma->vm_file) { |
1161 | /* read the contents of a file into the copy */ |
1162 | mm_segment_t old_fs; |
1163 | loff_t fpos; |
1164 | |
1165 | fpos = vma->vm_pgoff; |
1166 | fpos <<= PAGE_SHIFT; |
1167 | |
1168 | old_fs = get_fs(); |
1169 | set_fs(KERNEL_DS); |
1170 | ret = __vfs_read(vma->vm_file, base, len, &fpos); |
1171 | set_fs(old_fs); |
1172 | |
1173 | if (ret < 0) |
1174 | goto error_free; |
1175 | |
1176 | /* clear the last little bit */ |
1177 | if (ret < len) |
1178 | memset(base + ret, 0, len - ret); |
1179 | |
1180 | } |
1181 | |
1182 | return 0; |
1183 | |
1184 | error_free: |
1185 | free_page_series(region->vm_start, region->vm_top); |
1186 | region->vm_start = vma->vm_start = 0; |
1187 | region->vm_end = vma->vm_end = 0; |
1188 | region->vm_top = 0; |
1189 | return ret; |
1190 | |
1191 | enomem: |
1192 | pr_err("Allocation of length %lu from process %d (%s) failed\n", |
1193 | len, current->pid, current->comm); |
1194 | show_free_areas(0); |
1195 | return -ENOMEM; |
1196 | } |
1197 | |
1198 | /* |
1199 | * handle mapping creation for uClinux |
1200 | */ |
1201 | unsigned long do_mmap(struct file *file, |
1202 | unsigned long addr, |
1203 | unsigned long len, |
1204 | unsigned long prot, |
1205 | unsigned long flags, |
1206 | vm_flags_t vm_flags, |
1207 | unsigned long pgoff, |
1208 | unsigned long *populate) |
1209 | { |
1210 | struct vm_area_struct *vma; |
1211 | struct vm_region *region; |
1212 | struct rb_node *rb; |
1213 | unsigned long capabilities, result; |
1214 | int ret; |
1215 | |
1216 | *populate = 0; |
1217 | |
1218 | /* decide whether we should attempt the mapping, and if so what sort of |
1219 | * mapping */ |
1220 | ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, |
1221 | &capabilities); |
1222 | if (ret < 0) |
1223 | return ret; |
1224 | |
1225 | /* we ignore the address hint */ |
1226 | addr = 0; |
1227 | len = PAGE_ALIGN(len); |
1228 | |
1229 | /* we've determined that we can make the mapping, now translate what we |
1230 | * now know into VMA flags */ |
1231 | vm_flags |= determine_vm_flags(file, prot, flags, capabilities); |
1232 | |
1233 | /* we're going to need to record the mapping */ |
1234 | region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); |
1235 | if (!region) |
1236 | goto error_getting_region; |
1237 | |
1238 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
1239 | if (!vma) |
1240 | goto error_getting_vma; |
1241 | |
1242 | region->vm_usage = 1; |
1243 | region->vm_flags = vm_flags; |
1244 | region->vm_pgoff = pgoff; |
1245 | |
1246 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
1247 | vma->vm_flags = vm_flags; |
1248 | vma->vm_pgoff = pgoff; |
1249 | |
1250 | if (file) { |
1251 | region->vm_file = get_file(file); |
1252 | vma->vm_file = get_file(file); |
1253 | } |
1254 | |
1255 | down_write(&nommu_region_sem); |
1256 | |
1257 | /* if we want to share, we need to check for regions created by other |
1258 | * mmap() calls that overlap with our proposed mapping |
1259 | * - we can only share with a superset match on most regular files |
1260 | * - shared mappings on character devices and memory backed files are |
1261 | * permitted to overlap inexactly as far as we are concerned for in |
1262 | * these cases, sharing is handled in the driver or filesystem rather |
1263 | * than here |
1264 | */ |
1265 | if (vm_flags & VM_MAYSHARE) { |
1266 | struct vm_region *pregion; |
1267 | unsigned long pglen, rpglen, pgend, rpgend, start; |
1268 | |
1269 | pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1270 | pgend = pgoff + pglen; |
1271 | |
1272 | for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { |
1273 | pregion = rb_entry(rb, struct vm_region, vm_rb); |
1274 | |
1275 | if (!(pregion->vm_flags & VM_MAYSHARE)) |
1276 | continue; |
1277 | |
1278 | /* search for overlapping mappings on the same file */ |
1279 | if (file_inode(pregion->vm_file) != |
1280 | file_inode(file)) |
1281 | continue; |
1282 | |
1283 | if (pregion->vm_pgoff >= pgend) |
1284 | continue; |
1285 | |
1286 | rpglen = pregion->vm_end - pregion->vm_start; |
1287 | rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1288 | rpgend = pregion->vm_pgoff + rpglen; |
1289 | if (pgoff >= rpgend) |
1290 | continue; |
1291 | |
1292 | /* handle inexactly overlapping matches between |
1293 | * mappings */ |
1294 | if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && |
1295 | !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { |
1296 | /* new mapping is not a subset of the region */ |
1297 | if (!(capabilities & NOMMU_MAP_DIRECT)) |
1298 | goto sharing_violation; |
1299 | continue; |
1300 | } |
1301 | |
1302 | /* we've found a region we can share */ |
1303 | pregion->vm_usage++; |
1304 | vma->vm_region = pregion; |
1305 | start = pregion->vm_start; |
1306 | start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; |
1307 | vma->vm_start = start; |
1308 | vma->vm_end = start + len; |
1309 | |
1310 | if (pregion->vm_flags & VM_MAPPED_COPY) |
1311 | vma->vm_flags |= VM_MAPPED_COPY; |
1312 | else { |
1313 | ret = do_mmap_shared_file(vma); |
1314 | if (ret < 0) { |
1315 | vma->vm_region = NULL; |
1316 | vma->vm_start = 0; |
1317 | vma->vm_end = 0; |
1318 | pregion->vm_usage--; |
1319 | pregion = NULL; |
1320 | goto error_just_free; |
1321 | } |
1322 | } |
1323 | fput(region->vm_file); |
1324 | kmem_cache_free(vm_region_jar, region); |
1325 | region = pregion; |
1326 | result = start; |
1327 | goto share; |
1328 | } |
1329 | |
1330 | /* obtain the address at which to make a shared mapping |
1331 | * - this is the hook for quasi-memory character devices to |
1332 | * tell us the location of a shared mapping |
1333 | */ |
1334 | if (capabilities & NOMMU_MAP_DIRECT) { |
1335 | addr = file->f_op->get_unmapped_area(file, addr, len, |
1336 | pgoff, flags); |
1337 | if (IS_ERR_VALUE(addr)) { |
1338 | ret = addr; |
1339 | if (ret != -ENOSYS) |
1340 | goto error_just_free; |
1341 | |
1342 | /* the driver refused to tell us where to site |
1343 | * the mapping so we'll have to attempt to copy |
1344 | * it */ |
1345 | ret = -ENODEV; |
1346 | if (!(capabilities & NOMMU_MAP_COPY)) |
1347 | goto error_just_free; |
1348 | |
1349 | capabilities &= ~NOMMU_MAP_DIRECT; |
1350 | } else { |
1351 | vma->vm_start = region->vm_start = addr; |
1352 | vma->vm_end = region->vm_end = addr + len; |
1353 | } |
1354 | } |
1355 | } |
1356 | |
1357 | vma->vm_region = region; |
1358 | |
1359 | /* set up the mapping |
1360 | * - the region is filled in if NOMMU_MAP_DIRECT is still set |
1361 | */ |
1362 | if (file && vma->vm_flags & VM_SHARED) |
1363 | ret = do_mmap_shared_file(vma); |
1364 | else |
1365 | ret = do_mmap_private(vma, region, len, capabilities); |
1366 | if (ret < 0) |
1367 | goto error_just_free; |
1368 | add_nommu_region(region); |
1369 | |
1370 | /* clear anonymous mappings that don't ask for uninitialized data */ |
1371 | if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) |
1372 | memset((void *)region->vm_start, 0, |
1373 | region->vm_end - region->vm_start); |
1374 | |
1375 | /* okay... we have a mapping; now we have to register it */ |
1376 | result = vma->vm_start; |
1377 | |
1378 | current->mm->total_vm += len >> PAGE_SHIFT; |
1379 | |
1380 | share: |
1381 | add_vma_to_mm(current->mm, vma); |
1382 | |
1383 | /* we flush the region from the icache only when the first executable |
1384 | * mapping of it is made */ |
1385 | if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { |
1386 | flush_icache_range(region->vm_start, region->vm_end); |
1387 | region->vm_icache_flushed = true; |
1388 | } |
1389 | |
1390 | up_write(&nommu_region_sem); |
1391 | |
1392 | return result; |
1393 | |
1394 | error_just_free: |
1395 | up_write(&nommu_region_sem); |
1396 | error: |
1397 | if (region->vm_file) |
1398 | fput(region->vm_file); |
1399 | kmem_cache_free(vm_region_jar, region); |
1400 | if (vma->vm_file) |
1401 | fput(vma->vm_file); |
1402 | kmem_cache_free(vm_area_cachep, vma); |
1403 | return ret; |
1404 | |
1405 | sharing_violation: |
1406 | up_write(&nommu_region_sem); |
1407 | pr_warn("Attempt to share mismatched mappings\n"); |
1408 | ret = -EINVAL; |
1409 | goto error; |
1410 | |
1411 | error_getting_vma: |
1412 | kmem_cache_free(vm_region_jar, region); |
1413 | pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n", |
1414 | len, current->pid); |
1415 | show_free_areas(0); |
1416 | return -ENOMEM; |
1417 | |
1418 | error_getting_region: |
1419 | pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n", |
1420 | len, current->pid); |
1421 | show_free_areas(0); |
1422 | return -ENOMEM; |
1423 | } |
1424 | |
1425 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
1426 | unsigned long, prot, unsigned long, flags, |
1427 | unsigned long, fd, unsigned long, pgoff) |
1428 | { |
1429 | struct file *file = NULL; |
1430 | unsigned long retval = -EBADF; |
1431 | |
1432 | audit_mmap_fd(fd, flags); |
1433 | if (!(flags & MAP_ANONYMOUS)) { |
1434 | file = fget(fd); |
1435 | if (!file) |
1436 | goto out; |
1437 | } |
1438 | |
1439 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); |
1440 | |
1441 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
1442 | |
1443 | if (file) |
1444 | fput(file); |
1445 | out: |
1446 | return retval; |
1447 | } |
1448 | |
1449 | #ifdef __ARCH_WANT_SYS_OLD_MMAP |
1450 | struct mmap_arg_struct { |
1451 | unsigned long addr; |
1452 | unsigned long len; |
1453 | unsigned long prot; |
1454 | unsigned long flags; |
1455 | unsigned long fd; |
1456 | unsigned long offset; |
1457 | }; |
1458 | |
1459 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
1460 | { |
1461 | struct mmap_arg_struct a; |
1462 | |
1463 | if (copy_from_user(&a, arg, sizeof(a))) |
1464 | return -EFAULT; |
1465 | if (offset_in_page(a.offset)) |
1466 | return -EINVAL; |
1467 | |
1468 | return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
1469 | a.offset >> PAGE_SHIFT); |
1470 | } |
1471 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
1472 | |
1473 | /* |
1474 | * split a vma into two pieces at address 'addr', a new vma is allocated either |
1475 | * for the first part or the tail. |
1476 | */ |
1477 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, |
1478 | unsigned long addr, int new_below) |
1479 | { |
1480 | struct vm_area_struct *new; |
1481 | struct vm_region *region; |
1482 | unsigned long npages; |
1483 | |
1484 | /* we're only permitted to split anonymous regions (these should have |
1485 | * only a single usage on the region) */ |
1486 | if (vma->vm_file) |
1487 | return -ENOMEM; |
1488 | |
1489 | if (mm->map_count >= sysctl_max_map_count) |
1490 | return -ENOMEM; |
1491 | |
1492 | region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); |
1493 | if (!region) |
1494 | return -ENOMEM; |
1495 | |
1496 | new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
1497 | if (!new) { |
1498 | kmem_cache_free(vm_region_jar, region); |
1499 | return -ENOMEM; |
1500 | } |
1501 | |
1502 | /* most fields are the same, copy all, and then fixup */ |
1503 | *new = *vma; |
1504 | *region = *vma->vm_region; |
1505 | new->vm_region = region; |
1506 | |
1507 | npages = (addr - vma->vm_start) >> PAGE_SHIFT; |
1508 | |
1509 | if (new_below) { |
1510 | region->vm_top = region->vm_end = new->vm_end = addr; |
1511 | } else { |
1512 | region->vm_start = new->vm_start = addr; |
1513 | region->vm_pgoff = new->vm_pgoff += npages; |
1514 | } |
1515 | |
1516 | if (new->vm_ops && new->vm_ops->open) |
1517 | new->vm_ops->open(new); |
1518 | |
1519 | delete_vma_from_mm(vma); |
1520 | down_write(&nommu_region_sem); |
1521 | delete_nommu_region(vma->vm_region); |
1522 | if (new_below) { |
1523 | vma->vm_region->vm_start = vma->vm_start = addr; |
1524 | vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; |
1525 | } else { |
1526 | vma->vm_region->vm_end = vma->vm_end = addr; |
1527 | vma->vm_region->vm_top = addr; |
1528 | } |
1529 | add_nommu_region(vma->vm_region); |
1530 | add_nommu_region(new->vm_region); |
1531 | up_write(&nommu_region_sem); |
1532 | add_vma_to_mm(mm, vma); |
1533 | add_vma_to_mm(mm, new); |
1534 | return 0; |
1535 | } |
1536 | |
1537 | /* |
1538 | * shrink a VMA by removing the specified chunk from either the beginning or |
1539 | * the end |
1540 | */ |
1541 | static int shrink_vma(struct mm_struct *mm, |
1542 | struct vm_area_struct *vma, |
1543 | unsigned long from, unsigned long to) |
1544 | { |
1545 | struct vm_region *region; |
1546 | |
1547 | /* adjust the VMA's pointers, which may reposition it in the MM's tree |
1548 | * and list */ |
1549 | delete_vma_from_mm(vma); |
1550 | if (from > vma->vm_start) |
1551 | vma->vm_end = from; |
1552 | else |
1553 | vma->vm_start = to; |
1554 | add_vma_to_mm(mm, vma); |
1555 | |
1556 | /* cut the backing region down to size */ |
1557 | region = vma->vm_region; |
1558 | BUG_ON(region->vm_usage != 1); |
1559 | |
1560 | down_write(&nommu_region_sem); |
1561 | delete_nommu_region(region); |
1562 | if (from > region->vm_start) { |
1563 | to = region->vm_top; |
1564 | region->vm_top = region->vm_end = from; |
1565 | } else { |
1566 | region->vm_start = to; |
1567 | } |
1568 | add_nommu_region(region); |
1569 | up_write(&nommu_region_sem); |
1570 | |
1571 | free_page_series(from, to); |
1572 | return 0; |
1573 | } |
1574 | |
1575 | /* |
1576 | * release a mapping |
1577 | * - under NOMMU conditions the chunk to be unmapped must be backed by a single |
1578 | * VMA, though it need not cover the whole VMA |
1579 | */ |
1580 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) |
1581 | { |
1582 | struct vm_area_struct *vma; |
1583 | unsigned long end; |
1584 | int ret; |
1585 | |
1586 | len = PAGE_ALIGN(len); |
1587 | if (len == 0) |
1588 | return -EINVAL; |
1589 | |
1590 | end = start + len; |
1591 | |
1592 | /* find the first potentially overlapping VMA */ |
1593 | vma = find_vma(mm, start); |
1594 | if (!vma) { |
1595 | static int limit; |
1596 | if (limit < 5) { |
1597 | pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n", |
1598 | current->pid, current->comm, |
1599 | start, start + len - 1); |
1600 | limit++; |
1601 | } |
1602 | return -EINVAL; |
1603 | } |
1604 | |
1605 | /* we're allowed to split an anonymous VMA but not a file-backed one */ |
1606 | if (vma->vm_file) { |
1607 | do { |
1608 | if (start > vma->vm_start) |
1609 | return -EINVAL; |
1610 | if (end == vma->vm_end) |
1611 | goto erase_whole_vma; |
1612 | vma = vma->vm_next; |
1613 | } while (vma); |
1614 | return -EINVAL; |
1615 | } else { |
1616 | /* the chunk must be a subset of the VMA found */ |
1617 | if (start == vma->vm_start && end == vma->vm_end) |
1618 | goto erase_whole_vma; |
1619 | if (start < vma->vm_start || end > vma->vm_end) |
1620 | return -EINVAL; |
1621 | if (offset_in_page(start)) |
1622 | return -EINVAL; |
1623 | if (end != vma->vm_end && offset_in_page(end)) |
1624 | return -EINVAL; |
1625 | if (start != vma->vm_start && end != vma->vm_end) { |
1626 | ret = split_vma(mm, vma, start, 1); |
1627 | if (ret < 0) |
1628 | return ret; |
1629 | } |
1630 | return shrink_vma(mm, vma, start, end); |
1631 | } |
1632 | |
1633 | erase_whole_vma: |
1634 | delete_vma_from_mm(vma); |
1635 | delete_vma(mm, vma); |
1636 | return 0; |
1637 | } |
1638 | EXPORT_SYMBOL(do_munmap); |
1639 | |
1640 | int vm_munmap(unsigned long addr, size_t len) |
1641 | { |
1642 | struct mm_struct *mm = current->mm; |
1643 | int ret; |
1644 | |
1645 | down_write(&mm->mmap_sem); |
1646 | ret = do_munmap(mm, addr, len); |
1647 | up_write(&mm->mmap_sem); |
1648 | return ret; |
1649 | } |
1650 | EXPORT_SYMBOL(vm_munmap); |
1651 | |
1652 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
1653 | { |
1654 | return vm_munmap(addr, len); |
1655 | } |
1656 | |
1657 | /* |
1658 | * release all the mappings made in a process's VM space |
1659 | */ |
1660 | void exit_mmap(struct mm_struct *mm) |
1661 | { |
1662 | struct vm_area_struct *vma; |
1663 | |
1664 | if (!mm) |
1665 | return; |
1666 | |
1667 | mm->total_vm = 0; |
1668 | |
1669 | while ((vma = mm->mmap)) { |
1670 | mm->mmap = vma->vm_next; |
1671 | delete_vma_from_mm(vma); |
1672 | delete_vma(mm, vma); |
1673 | cond_resched(); |
1674 | } |
1675 | } |
1676 | |
1677 | int vm_brk(unsigned long addr, unsigned long len) |
1678 | { |
1679 | return -ENOMEM; |
1680 | } |
1681 | |
1682 | /* |
1683 | * expand (or shrink) an existing mapping, potentially moving it at the same |
1684 | * time (controlled by the MREMAP_MAYMOVE flag and available VM space) |
1685 | * |
1686 | * under NOMMU conditions, we only permit changing a mapping's size, and only |
1687 | * as long as it stays within the region allocated by do_mmap_private() and the |
1688 | * block is not shareable |
1689 | * |
1690 | * MREMAP_FIXED is not supported under NOMMU conditions |
1691 | */ |
1692 | static unsigned long do_mremap(unsigned long addr, |
1693 | unsigned long old_len, unsigned long new_len, |
1694 | unsigned long flags, unsigned long new_addr) |
1695 | { |
1696 | struct vm_area_struct *vma; |
1697 | |
1698 | /* insanity checks first */ |
1699 | old_len = PAGE_ALIGN(old_len); |
1700 | new_len = PAGE_ALIGN(new_len); |
1701 | if (old_len == 0 || new_len == 0) |
1702 | return (unsigned long) -EINVAL; |
1703 | |
1704 | if (offset_in_page(addr)) |
1705 | return -EINVAL; |
1706 | |
1707 | if (flags & MREMAP_FIXED && new_addr != addr) |
1708 | return (unsigned long) -EINVAL; |
1709 | |
1710 | vma = find_vma_exact(current->mm, addr, old_len); |
1711 | if (!vma) |
1712 | return (unsigned long) -EINVAL; |
1713 | |
1714 | if (vma->vm_end != vma->vm_start + old_len) |
1715 | return (unsigned long) -EFAULT; |
1716 | |
1717 | if (vma->vm_flags & VM_MAYSHARE) |
1718 | return (unsigned long) -EPERM; |
1719 | |
1720 | if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) |
1721 | return (unsigned long) -ENOMEM; |
1722 | |
1723 | /* all checks complete - do it */ |
1724 | vma->vm_end = vma->vm_start + new_len; |
1725 | return vma->vm_start; |
1726 | } |
1727 | |
1728 | SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, |
1729 | unsigned long, new_len, unsigned long, flags, |
1730 | unsigned long, new_addr) |
1731 | { |
1732 | unsigned long ret; |
1733 | |
1734 | down_write(¤t->mm->mmap_sem); |
1735 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); |
1736 | up_write(¤t->mm->mmap_sem); |
1737 | return ret; |
1738 | } |
1739 | |
1740 | struct page *follow_page_mask(struct vm_area_struct *vma, |
1741 | unsigned long address, unsigned int flags, |
1742 | unsigned int *page_mask) |
1743 | { |
1744 | *page_mask = 0; |
1745 | return NULL; |
1746 | } |
1747 | |
1748 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
1749 | unsigned long pfn, unsigned long size, pgprot_t prot) |
1750 | { |
1751 | if (addr != (pfn << PAGE_SHIFT)) |
1752 | return -EINVAL; |
1753 | |
1754 | vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; |
1755 | return 0; |
1756 | } |
1757 | EXPORT_SYMBOL(remap_pfn_range); |
1758 | |
1759 | int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
1760 | { |
1761 | unsigned long pfn = start >> PAGE_SHIFT; |
1762 | unsigned long vm_len = vma->vm_end - vma->vm_start; |
1763 | |
1764 | pfn += vma->vm_pgoff; |
1765 | return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
1766 | } |
1767 | EXPORT_SYMBOL(vm_iomap_memory); |
1768 | |
1769 | int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, |
1770 | unsigned long pgoff) |
1771 | { |
1772 | unsigned int size = vma->vm_end - vma->vm_start; |
1773 | |
1774 | if (!(vma->vm_flags & VM_USERMAP)) |
1775 | return -EINVAL; |
1776 | |
1777 | vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); |
1778 | vma->vm_end = vma->vm_start + size; |
1779 | |
1780 | return 0; |
1781 | } |
1782 | EXPORT_SYMBOL(remap_vmalloc_range); |
1783 | |
1784 | unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, |
1785 | unsigned long len, unsigned long pgoff, unsigned long flags) |
1786 | { |
1787 | return -ENOMEM; |
1788 | } |
1789 | |
1790 | void unmap_mapping_range(struct address_space *mapping, |
1791 | loff_t const holebegin, loff_t const holelen, |
1792 | int even_cows) |
1793 | { |
1794 | } |
1795 | EXPORT_SYMBOL(unmap_mapping_range); |
1796 | |
1797 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1798 | { |
1799 | BUG(); |
1800 | return 0; |
1801 | } |
1802 | EXPORT_SYMBOL(filemap_fault); |
1803 | |
1804 | void filemap_map_pages(struct fault_env *fe, |
1805 | pgoff_t start_pgoff, pgoff_t end_pgoff) |
1806 | { |
1807 | BUG(); |
1808 | } |
1809 | EXPORT_SYMBOL(filemap_map_pages); |
1810 | |
1811 | int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, |
1812 | unsigned long addr, void *buf, int len, unsigned int gup_flags) |
1813 | { |
1814 | struct vm_area_struct *vma; |
1815 | int write = gup_flags & FOLL_WRITE; |
1816 | |
1817 | down_read(&mm->mmap_sem); |
1818 | |
1819 | /* the access must start within one of the target process's mappings */ |
1820 | vma = find_vma(mm, addr); |
1821 | if (vma) { |
1822 | /* don't overrun this mapping */ |
1823 | if (addr + len >= vma->vm_end) |
1824 | len = vma->vm_end - addr; |
1825 | |
1826 | /* only read or write mappings where it is permitted */ |
1827 | if (write && vma->vm_flags & VM_MAYWRITE) |
1828 | copy_to_user_page(vma, NULL, addr, |
1829 | (void *) addr, buf, len); |
1830 | else if (!write && vma->vm_flags & VM_MAYREAD) |
1831 | copy_from_user_page(vma, NULL, addr, |
1832 | buf, (void *) addr, len); |
1833 | else |
1834 | len = 0; |
1835 | } else { |
1836 | len = 0; |
1837 | } |
1838 | |
1839 | up_read(&mm->mmap_sem); |
1840 | |
1841 | return len; |
1842 | } |
1843 | |
1844 | /** |
1845 | * @access_remote_vm - access another process' address space |
1846 | * @mm: the mm_struct of the target address space |
1847 | * @addr: start address to access |
1848 | * @buf: source or destination buffer |
1849 | * @len: number of bytes to transfer |
1850 | * @gup_flags: flags modifying lookup behaviour |
1851 | * |
1852 | * The caller must hold a reference on @mm. |
1853 | */ |
1854 | int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
1855 | void *buf, int len, unsigned int gup_flags) |
1856 | { |
1857 | return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags); |
1858 | } |
1859 | |
1860 | /* |
1861 | * Access another process' address space. |
1862 | * - source/target buffer must be kernel space |
1863 | */ |
1864 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, |
1865 | unsigned int gup_flags) |
1866 | { |
1867 | struct mm_struct *mm; |
1868 | |
1869 | if (addr + len < addr) |
1870 | return 0; |
1871 | |
1872 | mm = get_task_mm(tsk); |
1873 | if (!mm) |
1874 | return 0; |
1875 | |
1876 | len = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags); |
1877 | |
1878 | mmput(mm); |
1879 | return len; |
1880 | } |
1881 | |
1882 | /** |
1883 | * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode |
1884 | * @inode: The inode to check |
1885 | * @size: The current filesize of the inode |
1886 | * @newsize: The proposed filesize of the inode |
1887 | * |
1888 | * Check the shared mappings on an inode on behalf of a shrinking truncate to |
1889 | * make sure that that any outstanding VMAs aren't broken and then shrink the |
1890 | * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't |
1891 | * automatically grant mappings that are too large. |
1892 | */ |
1893 | int nommu_shrink_inode_mappings(struct inode *inode, size_t size, |
1894 | size_t newsize) |
1895 | { |
1896 | struct vm_area_struct *vma; |
1897 | struct vm_region *region; |
1898 | pgoff_t low, high; |
1899 | size_t r_size, r_top; |
1900 | |
1901 | low = newsize >> PAGE_SHIFT; |
1902 | high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1903 | |
1904 | down_write(&nommu_region_sem); |
1905 | i_mmap_lock_read(inode->i_mapping); |
1906 | |
1907 | /* search for VMAs that fall within the dead zone */ |
1908 | vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { |
1909 | /* found one - only interested if it's shared out of the page |
1910 | * cache */ |
1911 | if (vma->vm_flags & VM_SHARED) { |
1912 | i_mmap_unlock_read(inode->i_mapping); |
1913 | up_write(&nommu_region_sem); |
1914 | return -ETXTBSY; /* not quite true, but near enough */ |
1915 | } |
1916 | } |
1917 | |
1918 | /* reduce any regions that overlap the dead zone - if in existence, |
1919 | * these will be pointed to by VMAs that don't overlap the dead zone |
1920 | * |
1921 | * we don't check for any regions that start beyond the EOF as there |
1922 | * shouldn't be any |
1923 | */ |
1924 | vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) { |
1925 | if (!(vma->vm_flags & VM_SHARED)) |
1926 | continue; |
1927 | |
1928 | region = vma->vm_region; |
1929 | r_size = region->vm_top - region->vm_start; |
1930 | r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; |
1931 | |
1932 | if (r_top > newsize) { |
1933 | region->vm_top -= r_top - newsize; |
1934 | if (region->vm_end > region->vm_top) |
1935 | region->vm_end = region->vm_top; |
1936 | } |
1937 | } |
1938 | |
1939 | i_mmap_unlock_read(inode->i_mapping); |
1940 | up_write(&nommu_region_sem); |
1941 | return 0; |
1942 | } |
1943 | |
1944 | /* |
1945 | * Initialise sysctl_user_reserve_kbytes. |
1946 | * |
1947 | * This is intended to prevent a user from starting a single memory hogging |
1948 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
1949 | * mode. |
1950 | * |
1951 | * The default value is min(3% of free memory, 128MB) |
1952 | * 128MB is enough to recover with sshd/login, bash, and top/kill. |
1953 | */ |
1954 | static int __meminit init_user_reserve(void) |
1955 | { |
1956 | unsigned long free_kbytes; |
1957 | |
1958 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
1959 | |
1960 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); |
1961 | return 0; |
1962 | } |
1963 | subsys_initcall(init_user_reserve); |
1964 | |
1965 | /* |
1966 | * Initialise sysctl_admin_reserve_kbytes. |
1967 | * |
1968 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
1969 | * to log in and kill a memory hogging process. |
1970 | * |
1971 | * Systems with more than 256MB will reserve 8MB, enough to recover |
1972 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
1973 | * only reserve 3% of free pages by default. |
1974 | */ |
1975 | static int __meminit init_admin_reserve(void) |
1976 | { |
1977 | unsigned long free_kbytes; |
1978 | |
1979 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
1980 | |
1981 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); |
1982 | return 0; |
1983 | } |
1984 | subsys_initcall(init_admin_reserve); |
1985 |