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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 <linux/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 | static long __get_user_pages_unlocked(struct task_struct *tsk, | |
180 | struct mm_struct *mm, unsigned long start, | |
181 | unsigned long nr_pages, struct page **pages, | |
182 | unsigned int gup_flags) | |
183 | { | |
184 | long ret; | |
185 | down_read(&mm->mmap_sem); | |
186 | ret = __get_user_pages(tsk, mm, start, nr_pages, gup_flags, pages, | |
187 | NULL, NULL); | |
188 | up_read(&mm->mmap_sem); | |
189 | return ret; | |
190 | } | |
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 vm_fault *vmf, | |
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 | EXPORT_SYMBOL_GPL(access_process_vm); | |
1882 | ||
1883 | /** | |
1884 | * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode | |
1885 | * @inode: The inode to check | |
1886 | * @size: The current filesize of the inode | |
1887 | * @newsize: The proposed filesize of the inode | |
1888 | * | |
1889 | * Check the shared mappings on an inode on behalf of a shrinking truncate to | |
1890 | * make sure that that any outstanding VMAs aren't broken and then shrink the | |
1891 | * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't | |
1892 | * automatically grant mappings that are too large. | |
1893 | */ | |
1894 | int nommu_shrink_inode_mappings(struct inode *inode, size_t size, | |
1895 | size_t newsize) | |
1896 | { | |
1897 | struct vm_area_struct *vma; | |
1898 | struct vm_region *region; | |
1899 | pgoff_t low, high; | |
1900 | size_t r_size, r_top; | |
1901 | ||
1902 | low = newsize >> PAGE_SHIFT; | |
1903 | high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
1904 | ||
1905 | down_write(&nommu_region_sem); | |
1906 | i_mmap_lock_read(inode->i_mapping); | |
1907 | ||
1908 | /* search for VMAs that fall within the dead zone */ | |
1909 | vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { | |
1910 | /* found one - only interested if it's shared out of the page | |
1911 | * cache */ | |
1912 | if (vma->vm_flags & VM_SHARED) { | |
1913 | i_mmap_unlock_read(inode->i_mapping); | |
1914 | up_write(&nommu_region_sem); | |
1915 | return -ETXTBSY; /* not quite true, but near enough */ | |
1916 | } | |
1917 | } | |
1918 | ||
1919 | /* reduce any regions that overlap the dead zone - if in existence, | |
1920 | * these will be pointed to by VMAs that don't overlap the dead zone | |
1921 | * | |
1922 | * we don't check for any regions that start beyond the EOF as there | |
1923 | * shouldn't be any | |
1924 | */ | |
1925 | vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) { | |
1926 | if (!(vma->vm_flags & VM_SHARED)) | |
1927 | continue; | |
1928 | ||
1929 | region = vma->vm_region; | |
1930 | r_size = region->vm_top - region->vm_start; | |
1931 | r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; | |
1932 | ||
1933 | if (r_top > newsize) { | |
1934 | region->vm_top -= r_top - newsize; | |
1935 | if (region->vm_end > region->vm_top) | |
1936 | region->vm_end = region->vm_top; | |
1937 | } | |
1938 | } | |
1939 | ||
1940 | i_mmap_unlock_read(inode->i_mapping); | |
1941 | up_write(&nommu_region_sem); | |
1942 | return 0; | |
1943 | } | |
1944 | ||
1945 | /* | |
1946 | * Initialise sysctl_user_reserve_kbytes. | |
1947 | * | |
1948 | * This is intended to prevent a user from starting a single memory hogging | |
1949 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER | |
1950 | * mode. | |
1951 | * | |
1952 | * The default value is min(3% of free memory, 128MB) | |
1953 | * 128MB is enough to recover with sshd/login, bash, and top/kill. | |
1954 | */ | |
1955 | static int __meminit init_user_reserve(void) | |
1956 | { | |
1957 | unsigned long free_kbytes; | |
1958 | ||
1959 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
1960 | ||
1961 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); | |
1962 | return 0; | |
1963 | } | |
1964 | subsys_initcall(init_user_reserve); | |
1965 | ||
1966 | /* | |
1967 | * Initialise sysctl_admin_reserve_kbytes. | |
1968 | * | |
1969 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin | |
1970 | * to log in and kill a memory hogging process. | |
1971 | * | |
1972 | * Systems with more than 256MB will reserve 8MB, enough to recover | |
1973 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will | |
1974 | * only reserve 3% of free pages by default. | |
1975 | */ | |
1976 | static int __meminit init_admin_reserve(void) | |
1977 | { | |
1978 | unsigned long free_kbytes; | |
1979 | ||
1980 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); | |
1981 | ||
1982 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); | |
1983 | return 0; | |
1984 | } | |
1985 | subsys_initcall(init_admin_reserve); |