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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/sched/sysctl.h> |
37 | #include <linux/printk.h> |
38 | |
39 | #include <asm/uaccess.h> |
40 | #include <asm/tlb.h> |
41 | #include <asm/tlbflush.h> |
42 | #include <asm/mmu_context.h> |
43 | #include "internal.h" |
44 | |
45 | #if 0 |
46 | #define kenter(FMT, ...) \ |
47 | printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) |
48 | #define kleave(FMT, ...) \ |
49 | printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) |
50 | #define kdebug(FMT, ...) \ |
51 | printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) |
52 | #else |
53 | #define kenter(FMT, ...) \ |
54 | no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) |
55 | #define kleave(FMT, ...) \ |
56 | no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) |
57 | #define kdebug(FMT, ...) \ |
58 | no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) |
59 | #endif |
60 | |
61 | void *high_memory; |
62 | struct page *mem_map; |
63 | unsigned long max_mapnr; |
64 | unsigned long highest_memmap_pfn; |
65 | struct percpu_counter vm_committed_as; |
66 | int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ |
67 | int sysctl_overcommit_ratio = 50; /* default is 50% */ |
68 | unsigned long sysctl_overcommit_kbytes __read_mostly; |
69 | int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; |
70 | int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; |
71 | unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */ |
72 | unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */ |
73 | int heap_stack_gap = 0; |
74 | |
75 | atomic_long_t mmap_pages_allocated; |
76 | |
77 | /* |
78 | * The global memory commitment made in the system can be a metric |
79 | * that can be used to drive ballooning decisions when Linux is hosted |
80 | * as a guest. On Hyper-V, the host implements a policy engine for dynamically |
81 | * balancing memory across competing virtual machines that are hosted. |
82 | * Several metrics drive this policy engine including the guest reported |
83 | * memory commitment. |
84 | */ |
85 | unsigned long vm_memory_committed(void) |
86 | { |
87 | return percpu_counter_read_positive(&vm_committed_as); |
88 | } |
89 | |
90 | EXPORT_SYMBOL_GPL(vm_memory_committed); |
91 | |
92 | EXPORT_SYMBOL(mem_map); |
93 | |
94 | /* list of mapped, potentially shareable regions */ |
95 | static struct kmem_cache *vm_region_jar; |
96 | struct rb_root nommu_region_tree = RB_ROOT; |
97 | DECLARE_RWSEM(nommu_region_sem); |
98 | |
99 | const struct vm_operations_struct generic_file_vm_ops = { |
100 | }; |
101 | |
102 | /* |
103 | * Return the total memory allocated for this pointer, not |
104 | * just what the caller asked for. |
105 | * |
106 | * Doesn't have to be accurate, i.e. may have races. |
107 | */ |
108 | unsigned int kobjsize(const void *objp) |
109 | { |
110 | struct page *page; |
111 | |
112 | /* |
113 | * If the object we have should not have ksize performed on it, |
114 | * return size of 0 |
115 | */ |
116 | if (!objp || !virt_addr_valid(objp)) |
117 | return 0; |
118 | |
119 | page = virt_to_head_page(objp); |
120 | |
121 | /* |
122 | * If the allocator sets PageSlab, we know the pointer came from |
123 | * kmalloc(). |
124 | */ |
125 | if (PageSlab(page)) |
126 | return ksize(objp); |
127 | |
128 | /* |
129 | * If it's not a compound page, see if we have a matching VMA |
130 | * region. This test is intentionally done in reverse order, |
131 | * so if there's no VMA, we still fall through and hand back |
132 | * PAGE_SIZE for 0-order pages. |
133 | */ |
134 | if (!PageCompound(page)) { |
135 | struct vm_area_struct *vma; |
136 | |
137 | vma = find_vma(current->mm, (unsigned long)objp); |
138 | if (vma) |
139 | return vma->vm_end - vma->vm_start; |
140 | } |
141 | |
142 | /* |
143 | * The ksize() function is only guaranteed to work for pointers |
144 | * returned by kmalloc(). So handle arbitrary pointers here. |
145 | */ |
146 | return PAGE_SIZE << compound_order(page); |
147 | } |
148 | |
149 | long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
150 | unsigned long start, unsigned long nr_pages, |
151 | unsigned int foll_flags, struct page **pages, |
152 | struct vm_area_struct **vmas, int *nonblocking) |
153 | { |
154 | struct vm_area_struct *vma; |
155 | unsigned long vm_flags; |
156 | int i; |
157 | |
158 | /* calculate required read or write permissions. |
159 | * If FOLL_FORCE is set, we only require the "MAY" flags. |
160 | */ |
161 | vm_flags = (foll_flags & FOLL_WRITE) ? |
162 | (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); |
163 | vm_flags &= (foll_flags & FOLL_FORCE) ? |
164 | (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); |
165 | |
166 | for (i = 0; i < nr_pages; i++) { |
167 | vma = find_vma(mm, start); |
168 | if (!vma) |
169 | goto finish_or_fault; |
170 | |
171 | /* protect what we can, including chardevs */ |
172 | if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || |
173 | !(vm_flags & vma->vm_flags)) |
174 | goto finish_or_fault; |
175 | |
176 | if (pages) { |
177 | pages[i] = virt_to_page(start); |
178 | if (pages[i]) |
179 | page_cache_get(pages[i]); |
180 | } |
181 | if (vmas) |
182 | vmas[i] = vma; |
183 | start = (start + PAGE_SIZE) & PAGE_MASK; |
184 | } |
185 | |
186 | return i; |
187 | |
188 | finish_or_fault: |
189 | return i ? : -EFAULT; |
190 | } |
191 | |
192 | /* |
193 | * get a list of pages in an address range belonging to the specified process |
194 | * and indicate the VMA that covers each page |
195 | * - this is potentially dodgy as we may end incrementing the page count of a |
196 | * slab page or a secondary page from a compound page |
197 | * - don't permit access to VMAs that don't support it, such as I/O mappings |
198 | */ |
199 | long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, |
200 | unsigned long start, unsigned long nr_pages, |
201 | int write, int force, struct page **pages, |
202 | struct vm_area_struct **vmas) |
203 | { |
204 | int flags = 0; |
205 | |
206 | if (write) |
207 | flags |= FOLL_WRITE; |
208 | if (force) |
209 | flags |= FOLL_FORCE; |
210 | |
211 | return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, |
212 | NULL); |
213 | } |
214 | EXPORT_SYMBOL(get_user_pages); |
215 | |
216 | /** |
217 | * follow_pfn - look up PFN at a user virtual address |
218 | * @vma: memory mapping |
219 | * @address: user virtual address |
220 | * @pfn: location to store found PFN |
221 | * |
222 | * Only IO mappings and raw PFN mappings are allowed. |
223 | * |
224 | * Returns zero and the pfn at @pfn on success, -ve otherwise. |
225 | */ |
226 | int follow_pfn(struct vm_area_struct *vma, unsigned long address, |
227 | unsigned long *pfn) |
228 | { |
229 | if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) |
230 | return -EINVAL; |
231 | |
232 | *pfn = address >> PAGE_SHIFT; |
233 | return 0; |
234 | } |
235 | EXPORT_SYMBOL(follow_pfn); |
236 | |
237 | LIST_HEAD(vmap_area_list); |
238 | |
239 | void vfree(const void *addr) |
240 | { |
241 | kfree(addr); |
242 | } |
243 | EXPORT_SYMBOL(vfree); |
244 | |
245 | void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) |
246 | { |
247 | /* |
248 | * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() |
249 | * returns only a logical address. |
250 | */ |
251 | return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); |
252 | } |
253 | EXPORT_SYMBOL(__vmalloc); |
254 | |
255 | void *vmalloc_user(unsigned long size) |
256 | { |
257 | void *ret; |
258 | |
259 | ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, |
260 | PAGE_KERNEL); |
261 | if (ret) { |
262 | struct vm_area_struct *vma; |
263 | |
264 | down_write(¤t->mm->mmap_sem); |
265 | vma = find_vma(current->mm, (unsigned long)ret); |
266 | if (vma) |
267 | vma->vm_flags |= VM_USERMAP; |
268 | up_write(¤t->mm->mmap_sem); |
269 | } |
270 | |
271 | return ret; |
272 | } |
273 | EXPORT_SYMBOL(vmalloc_user); |
274 | |
275 | struct page *vmalloc_to_page(const void *addr) |
276 | { |
277 | return virt_to_page(addr); |
278 | } |
279 | EXPORT_SYMBOL(vmalloc_to_page); |
280 | |
281 | unsigned long vmalloc_to_pfn(const void *addr) |
282 | { |
283 | return page_to_pfn(virt_to_page(addr)); |
284 | } |
285 | EXPORT_SYMBOL(vmalloc_to_pfn); |
286 | |
287 | long vread(char *buf, char *addr, unsigned long count) |
288 | { |
289 | /* Don't allow overflow */ |
290 | if ((unsigned long) buf + count < count) |
291 | count = -(unsigned long) buf; |
292 | |
293 | memcpy(buf, addr, count); |
294 | return count; |
295 | } |
296 | |
297 | long vwrite(char *buf, char *addr, unsigned long count) |
298 | { |
299 | /* Don't allow overflow */ |
300 | if ((unsigned long) addr + count < count) |
301 | count = -(unsigned long) addr; |
302 | |
303 | memcpy(addr, buf, count); |
304 | return count; |
305 | } |
306 | |
307 | /* |
308 | * vmalloc - allocate virtually continguos memory |
309 | * |
310 | * @size: allocation size |
311 | * |
312 | * Allocate enough pages to cover @size from the page level |
313 | * allocator and map them into continguos kernel virtual space. |
314 | * |
315 | * For tight control over page level allocator and protection flags |
316 | * use __vmalloc() instead. |
317 | */ |
318 | void *vmalloc(unsigned long size) |
319 | { |
320 | return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); |
321 | } |
322 | EXPORT_SYMBOL(vmalloc); |
323 | |
324 | /* |
325 | * vzalloc - allocate virtually continguos memory with zero fill |
326 | * |
327 | * @size: allocation size |
328 | * |
329 | * Allocate enough pages to cover @size from the page level |
330 | * allocator and map them into continguos kernel virtual space. |
331 | * The memory allocated is set to zero. |
332 | * |
333 | * For tight control over page level allocator and protection flags |
334 | * use __vmalloc() instead. |
335 | */ |
336 | void *vzalloc(unsigned long size) |
337 | { |
338 | return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, |
339 | PAGE_KERNEL); |
340 | } |
341 | EXPORT_SYMBOL(vzalloc); |
342 | |
343 | /** |
344 | * vmalloc_node - allocate memory on a specific node |
345 | * @size: allocation size |
346 | * @node: numa node |
347 | * |
348 | * Allocate enough pages to cover @size from the page level |
349 | * allocator and map them into contiguous kernel virtual space. |
350 | * |
351 | * For tight control over page level allocator and protection flags |
352 | * use __vmalloc() instead. |
353 | */ |
354 | void *vmalloc_node(unsigned long size, int node) |
355 | { |
356 | return vmalloc(size); |
357 | } |
358 | EXPORT_SYMBOL(vmalloc_node); |
359 | |
360 | /** |
361 | * vzalloc_node - allocate memory on a specific node with zero fill |
362 | * @size: allocation size |
363 | * @node: numa node |
364 | * |
365 | * Allocate enough pages to cover @size from the page level |
366 | * allocator and map them into contiguous kernel virtual space. |
367 | * The memory allocated is set to zero. |
368 | * |
369 | * For tight control over page level allocator and protection flags |
370 | * use __vmalloc() instead. |
371 | */ |
372 | void *vzalloc_node(unsigned long size, int node) |
373 | { |
374 | return vzalloc(size); |
375 | } |
376 | EXPORT_SYMBOL(vzalloc_node); |
377 | |
378 | #ifndef PAGE_KERNEL_EXEC |
379 | # define PAGE_KERNEL_EXEC PAGE_KERNEL |
380 | #endif |
381 | |
382 | /** |
383 | * vmalloc_exec - allocate virtually contiguous, executable memory |
384 | * @size: allocation size |
385 | * |
386 | * Kernel-internal function to allocate enough pages to cover @size |
387 | * the page level allocator and map them into contiguous and |
388 | * executable kernel virtual space. |
389 | * |
390 | * For tight control over page level allocator and protection flags |
391 | * use __vmalloc() instead. |
392 | */ |
393 | |
394 | void *vmalloc_exec(unsigned long size) |
395 | { |
396 | return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); |
397 | } |
398 | |
399 | /** |
400 | * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) |
401 | * @size: allocation size |
402 | * |
403 | * Allocate enough 32bit PA addressable pages to cover @size from the |
404 | * page level allocator and map them into continguos kernel virtual space. |
405 | */ |
406 | void *vmalloc_32(unsigned long size) |
407 | { |
408 | return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); |
409 | } |
410 | EXPORT_SYMBOL(vmalloc_32); |
411 | |
412 | /** |
413 | * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory |
414 | * @size: allocation size |
415 | * |
416 | * The resulting memory area is 32bit addressable and zeroed so it can be |
417 | * mapped to userspace without leaking data. |
418 | * |
419 | * VM_USERMAP is set on the corresponding VMA so that subsequent calls to |
420 | * remap_vmalloc_range() are permissible. |
421 | */ |
422 | void *vmalloc_32_user(unsigned long size) |
423 | { |
424 | /* |
425 | * We'll have to sort out the ZONE_DMA bits for 64-bit, |
426 | * but for now this can simply use vmalloc_user() directly. |
427 | */ |
428 | return vmalloc_user(size); |
429 | } |
430 | EXPORT_SYMBOL(vmalloc_32_user); |
431 | |
432 | void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) |
433 | { |
434 | BUG(); |
435 | return NULL; |
436 | } |
437 | EXPORT_SYMBOL(vmap); |
438 | |
439 | void vunmap(const void *addr) |
440 | { |
441 | BUG(); |
442 | } |
443 | EXPORT_SYMBOL(vunmap); |
444 | |
445 | void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) |
446 | { |
447 | BUG(); |
448 | return NULL; |
449 | } |
450 | EXPORT_SYMBOL(vm_map_ram); |
451 | |
452 | void vm_unmap_ram(const void *mem, unsigned int count) |
453 | { |
454 | BUG(); |
455 | } |
456 | EXPORT_SYMBOL(vm_unmap_ram); |
457 | |
458 | void vm_unmap_aliases(void) |
459 | { |
460 | } |
461 | EXPORT_SYMBOL_GPL(vm_unmap_aliases); |
462 | |
463 | /* |
464 | * Implement a stub for vmalloc_sync_all() if the architecture chose not to |
465 | * have one. |
466 | */ |
467 | void __weak vmalloc_sync_all(void) |
468 | { |
469 | } |
470 | |
471 | /** |
472 | * alloc_vm_area - allocate a range of kernel address space |
473 | * @size: size of the area |
474 | * |
475 | * Returns: NULL on failure, vm_struct on success |
476 | * |
477 | * This function reserves a range of kernel address space, and |
478 | * allocates pagetables to map that range. No actual mappings |
479 | * are created. If the kernel address space is not shared |
480 | * between processes, it syncs the pagetable across all |
481 | * processes. |
482 | */ |
483 | struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes) |
484 | { |
485 | BUG(); |
486 | return NULL; |
487 | } |
488 | EXPORT_SYMBOL_GPL(alloc_vm_area); |
489 | |
490 | void free_vm_area(struct vm_struct *area) |
491 | { |
492 | BUG(); |
493 | } |
494 | EXPORT_SYMBOL_GPL(free_vm_area); |
495 | |
496 | int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, |
497 | struct page *page) |
498 | { |
499 | return -EINVAL; |
500 | } |
501 | EXPORT_SYMBOL(vm_insert_page); |
502 | |
503 | /* |
504 | * sys_brk() for the most part doesn't need the global kernel |
505 | * lock, except when an application is doing something nasty |
506 | * like trying to un-brk an area that has already been mapped |
507 | * to a regular file. in this case, the unmapping will need |
508 | * to invoke file system routines that need the global lock. |
509 | */ |
510 | SYSCALL_DEFINE1(brk, unsigned long, brk) |
511 | { |
512 | struct mm_struct *mm = current->mm; |
513 | |
514 | if (brk < mm->start_brk || brk > mm->context.end_brk) |
515 | return mm->brk; |
516 | |
517 | if (mm->brk == brk) |
518 | return mm->brk; |
519 | |
520 | /* |
521 | * Always allow shrinking brk |
522 | */ |
523 | if (brk <= mm->brk) { |
524 | mm->brk = brk; |
525 | return brk; |
526 | } |
527 | |
528 | /* |
529 | * Ok, looks good - let it rip. |
530 | */ |
531 | flush_icache_range(mm->brk, brk); |
532 | return mm->brk = brk; |
533 | } |
534 | |
535 | /* |
536 | * initialise the VMA and region record slabs |
537 | */ |
538 | void __init mmap_init(void) |
539 | { |
540 | int ret; |
541 | |
542 | ret = percpu_counter_init(&vm_committed_as, 0); |
543 | VM_BUG_ON(ret); |
544 | vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); |
545 | } |
546 | |
547 | /* |
548 | * validate the region tree |
549 | * - the caller must hold the region lock |
550 | */ |
551 | #ifdef CONFIG_DEBUG_NOMMU_REGIONS |
552 | static noinline void validate_nommu_regions(void) |
553 | { |
554 | struct vm_region *region, *last; |
555 | struct rb_node *p, *lastp; |
556 | |
557 | lastp = rb_first(&nommu_region_tree); |
558 | if (!lastp) |
559 | return; |
560 | |
561 | last = rb_entry(lastp, struct vm_region, vm_rb); |
562 | BUG_ON(unlikely(last->vm_end <= last->vm_start)); |
563 | BUG_ON(unlikely(last->vm_top < last->vm_end)); |
564 | |
565 | while ((p = rb_next(lastp))) { |
566 | region = rb_entry(p, struct vm_region, vm_rb); |
567 | last = rb_entry(lastp, struct vm_region, vm_rb); |
568 | |
569 | BUG_ON(unlikely(region->vm_end <= region->vm_start)); |
570 | BUG_ON(unlikely(region->vm_top < region->vm_end)); |
571 | BUG_ON(unlikely(region->vm_start < last->vm_top)); |
572 | |
573 | lastp = p; |
574 | } |
575 | } |
576 | #else |
577 | static void validate_nommu_regions(void) |
578 | { |
579 | } |
580 | #endif |
581 | |
582 | /* |
583 | * add a region into the global tree |
584 | */ |
585 | static void add_nommu_region(struct vm_region *region) |
586 | { |
587 | struct vm_region *pregion; |
588 | struct rb_node **p, *parent; |
589 | |
590 | validate_nommu_regions(); |
591 | |
592 | parent = NULL; |
593 | p = &nommu_region_tree.rb_node; |
594 | while (*p) { |
595 | parent = *p; |
596 | pregion = rb_entry(parent, struct vm_region, vm_rb); |
597 | if (region->vm_start < pregion->vm_start) |
598 | p = &(*p)->rb_left; |
599 | else if (region->vm_start > pregion->vm_start) |
600 | p = &(*p)->rb_right; |
601 | else if (pregion == region) |
602 | return; |
603 | else |
604 | BUG(); |
605 | } |
606 | |
607 | rb_link_node(®ion->vm_rb, parent, p); |
608 | rb_insert_color(®ion->vm_rb, &nommu_region_tree); |
609 | |
610 | validate_nommu_regions(); |
611 | } |
612 | |
613 | /* |
614 | * delete a region from the global tree |
615 | */ |
616 | static void delete_nommu_region(struct vm_region *region) |
617 | { |
618 | BUG_ON(!nommu_region_tree.rb_node); |
619 | |
620 | validate_nommu_regions(); |
621 | rb_erase(®ion->vm_rb, &nommu_region_tree); |
622 | validate_nommu_regions(); |
623 | } |
624 | |
625 | /* |
626 | * free a contiguous series of pages |
627 | */ |
628 | static void free_page_series(unsigned long from, unsigned long to) |
629 | { |
630 | for (; from < to; from += PAGE_SIZE) { |
631 | struct page *page = virt_to_page(from); |
632 | |
633 | kdebug("- free %lx", from); |
634 | atomic_long_dec(&mmap_pages_allocated); |
635 | if (page_count(page) != 1) |
636 | kdebug("free page %p: refcount not one: %d", |
637 | page, page_count(page)); |
638 | put_page(page); |
639 | } |
640 | } |
641 | |
642 | /* |
643 | * release a reference to a region |
644 | * - the caller must hold the region semaphore for writing, which this releases |
645 | * - the region may not have been added to the tree yet, in which case vm_top |
646 | * will equal vm_start |
647 | */ |
648 | static void __put_nommu_region(struct vm_region *region) |
649 | __releases(nommu_region_sem) |
650 | { |
651 | kenter("%p{%d}", region, region->vm_usage); |
652 | |
653 | BUG_ON(!nommu_region_tree.rb_node); |
654 | |
655 | if (--region->vm_usage == 0) { |
656 | if (region->vm_top > region->vm_start) |
657 | delete_nommu_region(region); |
658 | up_write(&nommu_region_sem); |
659 | |
660 | if (region->vm_file) |
661 | fput(region->vm_file); |
662 | |
663 | /* IO memory and memory shared directly out of the pagecache |
664 | * from ramfs/tmpfs mustn't be released here */ |
665 | if (region->vm_flags & VM_MAPPED_COPY) { |
666 | kdebug("free series"); |
667 | free_page_series(region->vm_start, region->vm_top); |
668 | } |
669 | kmem_cache_free(vm_region_jar, region); |
670 | } else { |
671 | up_write(&nommu_region_sem); |
672 | } |
673 | } |
674 | |
675 | /* |
676 | * release a reference to a region |
677 | */ |
678 | static void put_nommu_region(struct vm_region *region) |
679 | { |
680 | down_write(&nommu_region_sem); |
681 | __put_nommu_region(region); |
682 | } |
683 | |
684 | /* |
685 | * update protection on a vma |
686 | */ |
687 | static void protect_vma(struct vm_area_struct *vma, unsigned long flags) |
688 | { |
689 | #ifdef CONFIG_MPU |
690 | struct mm_struct *mm = vma->vm_mm; |
691 | long start = vma->vm_start & PAGE_MASK; |
692 | while (start < vma->vm_end) { |
693 | protect_page(mm, start, flags); |
694 | start += PAGE_SIZE; |
695 | } |
696 | update_protections(mm); |
697 | #endif |
698 | } |
699 | |
700 | /* |
701 | * add a VMA into a process's mm_struct in the appropriate place in the list |
702 | * and tree and add to the address space's page tree also if not an anonymous |
703 | * page |
704 | * - should be called with mm->mmap_sem held writelocked |
705 | */ |
706 | static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) |
707 | { |
708 | struct vm_area_struct *pvma, *prev; |
709 | struct address_space *mapping; |
710 | struct rb_node **p, *parent, *rb_prev; |
711 | |
712 | kenter(",%p", vma); |
713 | |
714 | BUG_ON(!vma->vm_region); |
715 | |
716 | mm->map_count++; |
717 | vma->vm_mm = mm; |
718 | |
719 | protect_vma(vma, vma->vm_flags); |
720 | |
721 | /* add the VMA to the mapping */ |
722 | if (vma->vm_file) { |
723 | mapping = vma->vm_file->f_mapping; |
724 | |
725 | mutex_lock(&mapping->i_mmap_mutex); |
726 | flush_dcache_mmap_lock(mapping); |
727 | vma_interval_tree_insert(vma, &mapping->i_mmap); |
728 | flush_dcache_mmap_unlock(mapping); |
729 | mutex_unlock(&mapping->i_mmap_mutex); |
730 | } |
731 | |
732 | /* add the VMA to the tree */ |
733 | parent = rb_prev = NULL; |
734 | p = &mm->mm_rb.rb_node; |
735 | while (*p) { |
736 | parent = *p; |
737 | pvma = rb_entry(parent, struct vm_area_struct, vm_rb); |
738 | |
739 | /* sort by: start addr, end addr, VMA struct addr in that order |
740 | * (the latter is necessary as we may get identical VMAs) */ |
741 | if (vma->vm_start < pvma->vm_start) |
742 | p = &(*p)->rb_left; |
743 | else if (vma->vm_start > pvma->vm_start) { |
744 | rb_prev = parent; |
745 | p = &(*p)->rb_right; |
746 | } else if (vma->vm_end < pvma->vm_end) |
747 | p = &(*p)->rb_left; |
748 | else if (vma->vm_end > pvma->vm_end) { |
749 | rb_prev = parent; |
750 | p = &(*p)->rb_right; |
751 | } else if (vma < pvma) |
752 | p = &(*p)->rb_left; |
753 | else if (vma > pvma) { |
754 | rb_prev = parent; |
755 | p = &(*p)->rb_right; |
756 | } else |
757 | BUG(); |
758 | } |
759 | |
760 | rb_link_node(&vma->vm_rb, parent, p); |
761 | rb_insert_color(&vma->vm_rb, &mm->mm_rb); |
762 | |
763 | /* add VMA to the VMA list also */ |
764 | prev = NULL; |
765 | if (rb_prev) |
766 | prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); |
767 | |
768 | __vma_link_list(mm, vma, prev, parent); |
769 | } |
770 | |
771 | /* |
772 | * delete a VMA from its owning mm_struct and address space |
773 | */ |
774 | static void delete_vma_from_mm(struct vm_area_struct *vma) |
775 | { |
776 | int i; |
777 | struct address_space *mapping; |
778 | struct mm_struct *mm = vma->vm_mm; |
779 | struct task_struct *curr = current; |
780 | |
781 | kenter("%p", vma); |
782 | |
783 | protect_vma(vma, 0); |
784 | |
785 | mm->map_count--; |
786 | for (i = 0; i < VMACACHE_SIZE; i++) { |
787 | /* if the vma is cached, invalidate the entire cache */ |
788 | if (curr->vmacache[i] == vma) { |
789 | vmacache_invalidate(mm); |
790 | break; |
791 | } |
792 | } |
793 | |
794 | /* remove the VMA from the mapping */ |
795 | if (vma->vm_file) { |
796 | mapping = vma->vm_file->f_mapping; |
797 | |
798 | mutex_lock(&mapping->i_mmap_mutex); |
799 | flush_dcache_mmap_lock(mapping); |
800 | vma_interval_tree_remove(vma, &mapping->i_mmap); |
801 | flush_dcache_mmap_unlock(mapping); |
802 | mutex_unlock(&mapping->i_mmap_mutex); |
803 | } |
804 | |
805 | /* remove from the MM's tree and list */ |
806 | rb_erase(&vma->vm_rb, &mm->mm_rb); |
807 | |
808 | if (vma->vm_prev) |
809 | vma->vm_prev->vm_next = vma->vm_next; |
810 | else |
811 | mm->mmap = vma->vm_next; |
812 | |
813 | if (vma->vm_next) |
814 | vma->vm_next->vm_prev = vma->vm_prev; |
815 | } |
816 | |
817 | /* |
818 | * destroy a VMA record |
819 | */ |
820 | static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) |
821 | { |
822 | kenter("%p", vma); |
823 | if (vma->vm_ops && vma->vm_ops->close) |
824 | vma->vm_ops->close(vma); |
825 | if (vma->vm_file) |
826 | fput(vma->vm_file); |
827 | put_nommu_region(vma->vm_region); |
828 | kmem_cache_free(vm_area_cachep, vma); |
829 | } |
830 | |
831 | /* |
832 | * look up the first VMA in which addr resides, NULL if none |
833 | * - should be called with mm->mmap_sem at least held readlocked |
834 | */ |
835 | struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) |
836 | { |
837 | struct vm_area_struct *vma; |
838 | |
839 | /* check the cache first */ |
840 | vma = vmacache_find(mm, addr); |
841 | if (likely(vma)) |
842 | return vma; |
843 | |
844 | /* trawl the list (there may be multiple mappings in which addr |
845 | * resides) */ |
846 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
847 | if (vma->vm_start > addr) |
848 | return NULL; |
849 | if (vma->vm_end > addr) { |
850 | vmacache_update(addr, vma); |
851 | return vma; |
852 | } |
853 | } |
854 | |
855 | return NULL; |
856 | } |
857 | EXPORT_SYMBOL(find_vma); |
858 | |
859 | /* |
860 | * find a VMA |
861 | * - we don't extend stack VMAs under NOMMU conditions |
862 | */ |
863 | struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) |
864 | { |
865 | return find_vma(mm, addr); |
866 | } |
867 | |
868 | /* |
869 | * expand a stack to a given address |
870 | * - not supported under NOMMU conditions |
871 | */ |
872 | int expand_stack(struct vm_area_struct *vma, unsigned long address) |
873 | { |
874 | return -ENOMEM; |
875 | } |
876 | |
877 | /* |
878 | * look up the first VMA exactly that exactly matches addr |
879 | * - should be called with mm->mmap_sem at least held readlocked |
880 | */ |
881 | static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, |
882 | unsigned long addr, |
883 | unsigned long len) |
884 | { |
885 | struct vm_area_struct *vma; |
886 | unsigned long end = addr + len; |
887 | |
888 | /* check the cache first */ |
889 | vma = vmacache_find_exact(mm, addr, end); |
890 | if (vma) |
891 | return vma; |
892 | |
893 | /* trawl the list (there may be multiple mappings in which addr |
894 | * resides) */ |
895 | for (vma = mm->mmap; vma; vma = vma->vm_next) { |
896 | if (vma->vm_start < addr) |
897 | continue; |
898 | if (vma->vm_start > addr) |
899 | return NULL; |
900 | if (vma->vm_end == end) { |
901 | vmacache_update(addr, vma); |
902 | return vma; |
903 | } |
904 | } |
905 | |
906 | return NULL; |
907 | } |
908 | |
909 | /* |
910 | * determine whether a mapping should be permitted and, if so, what sort of |
911 | * mapping we're capable of supporting |
912 | */ |
913 | static int validate_mmap_request(struct file *file, |
914 | unsigned long addr, |
915 | unsigned long len, |
916 | unsigned long prot, |
917 | unsigned long flags, |
918 | unsigned long pgoff, |
919 | unsigned long *_capabilities) |
920 | { |
921 | unsigned long capabilities, rlen; |
922 | int ret; |
923 | |
924 | /* do the simple checks first */ |
925 | if (flags & MAP_FIXED) { |
926 | printk(KERN_DEBUG |
927 | "%d: Can't do fixed-address/overlay mmap of RAM\n", |
928 | current->pid); |
929 | return -EINVAL; |
930 | } |
931 | |
932 | if ((flags & MAP_TYPE) != MAP_PRIVATE && |
933 | (flags & MAP_TYPE) != MAP_SHARED) |
934 | return -EINVAL; |
935 | |
936 | if (!len) |
937 | return -EINVAL; |
938 | |
939 | /* Careful about overflows.. */ |
940 | rlen = PAGE_ALIGN(len); |
941 | if (!rlen || rlen > TASK_SIZE) |
942 | return -ENOMEM; |
943 | |
944 | /* offset overflow? */ |
945 | if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) |
946 | return -EOVERFLOW; |
947 | |
948 | if (file) { |
949 | /* validate file mapping requests */ |
950 | struct address_space *mapping; |
951 | |
952 | /* files must support mmap */ |
953 | if (!file->f_op->mmap) |
954 | return -ENODEV; |
955 | |
956 | /* work out if what we've got could possibly be shared |
957 | * - we support chardevs that provide their own "memory" |
958 | * - we support files/blockdevs that are memory backed |
959 | */ |
960 | mapping = file->f_mapping; |
961 | if (!mapping) |
962 | mapping = file_inode(file)->i_mapping; |
963 | |
964 | capabilities = 0; |
965 | if (mapping && mapping->backing_dev_info) |
966 | capabilities = mapping->backing_dev_info->capabilities; |
967 | |
968 | if (!capabilities) { |
969 | /* no explicit capabilities set, so assume some |
970 | * defaults */ |
971 | switch (file_inode(file)->i_mode & S_IFMT) { |
972 | case S_IFREG: |
973 | case S_IFBLK: |
974 | capabilities = BDI_CAP_MAP_COPY; |
975 | break; |
976 | |
977 | case S_IFCHR: |
978 | capabilities = |
979 | BDI_CAP_MAP_DIRECT | |
980 | BDI_CAP_READ_MAP | |
981 | BDI_CAP_WRITE_MAP; |
982 | break; |
983 | |
984 | default: |
985 | return -EINVAL; |
986 | } |
987 | } |
988 | |
989 | /* eliminate any capabilities that we can't support on this |
990 | * device */ |
991 | if (!file->f_op->get_unmapped_area) |
992 | capabilities &= ~BDI_CAP_MAP_DIRECT; |
993 | if (!file->f_op->read) |
994 | capabilities &= ~BDI_CAP_MAP_COPY; |
995 | |
996 | /* The file shall have been opened with read permission. */ |
997 | if (!(file->f_mode & FMODE_READ)) |
998 | return -EACCES; |
999 | |
1000 | if (flags & MAP_SHARED) { |
1001 | /* do checks for writing, appending and locking */ |
1002 | if ((prot & PROT_WRITE) && |
1003 | !(file->f_mode & FMODE_WRITE)) |
1004 | return -EACCES; |
1005 | |
1006 | if (IS_APPEND(file_inode(file)) && |
1007 | (file->f_mode & FMODE_WRITE)) |
1008 | return -EACCES; |
1009 | |
1010 | if (locks_verify_locked(file)) |
1011 | return -EAGAIN; |
1012 | |
1013 | if (!(capabilities & BDI_CAP_MAP_DIRECT)) |
1014 | return -ENODEV; |
1015 | |
1016 | /* we mustn't privatise shared mappings */ |
1017 | capabilities &= ~BDI_CAP_MAP_COPY; |
1018 | } else { |
1019 | /* we're going to read the file into private memory we |
1020 | * allocate */ |
1021 | if (!(capabilities & BDI_CAP_MAP_COPY)) |
1022 | return -ENODEV; |
1023 | |
1024 | /* we don't permit a private writable mapping to be |
1025 | * shared with the backing device */ |
1026 | if (prot & PROT_WRITE) |
1027 | capabilities &= ~BDI_CAP_MAP_DIRECT; |
1028 | } |
1029 | |
1030 | if (capabilities & BDI_CAP_MAP_DIRECT) { |
1031 | if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || |
1032 | ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || |
1033 | ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) |
1034 | ) { |
1035 | capabilities &= ~BDI_CAP_MAP_DIRECT; |
1036 | if (flags & MAP_SHARED) { |
1037 | printk(KERN_WARNING |
1038 | "MAP_SHARED not completely supported on !MMU\n"); |
1039 | return -EINVAL; |
1040 | } |
1041 | } |
1042 | } |
1043 | |
1044 | /* handle executable mappings and implied executable |
1045 | * mappings */ |
1046 | if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { |
1047 | if (prot & PROT_EXEC) |
1048 | return -EPERM; |
1049 | } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { |
1050 | /* handle implication of PROT_EXEC by PROT_READ */ |
1051 | if (current->personality & READ_IMPLIES_EXEC) { |
1052 | if (capabilities & BDI_CAP_EXEC_MAP) |
1053 | prot |= PROT_EXEC; |
1054 | } |
1055 | } else if ((prot & PROT_READ) && |
1056 | (prot & PROT_EXEC) && |
1057 | !(capabilities & BDI_CAP_EXEC_MAP) |
1058 | ) { |
1059 | /* backing file is not executable, try to copy */ |
1060 | capabilities &= ~BDI_CAP_MAP_DIRECT; |
1061 | } |
1062 | } else { |
1063 | /* anonymous mappings are always memory backed and can be |
1064 | * privately mapped |
1065 | */ |
1066 | capabilities = BDI_CAP_MAP_COPY; |
1067 | |
1068 | /* handle PROT_EXEC implication by PROT_READ */ |
1069 | if ((prot & PROT_READ) && |
1070 | (current->personality & READ_IMPLIES_EXEC)) |
1071 | prot |= PROT_EXEC; |
1072 | } |
1073 | |
1074 | /* allow the security API to have its say */ |
1075 | ret = security_mmap_addr(addr); |
1076 | if (ret < 0) |
1077 | return ret; |
1078 | |
1079 | /* looks okay */ |
1080 | *_capabilities = capabilities; |
1081 | return 0; |
1082 | } |
1083 | |
1084 | /* |
1085 | * we've determined that we can make the mapping, now translate what we |
1086 | * now know into VMA flags |
1087 | */ |
1088 | static unsigned long determine_vm_flags(struct file *file, |
1089 | unsigned long prot, |
1090 | unsigned long flags, |
1091 | unsigned long capabilities) |
1092 | { |
1093 | unsigned long vm_flags; |
1094 | |
1095 | vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); |
1096 | /* vm_flags |= mm->def_flags; */ |
1097 | |
1098 | if (!(capabilities & BDI_CAP_MAP_DIRECT)) { |
1099 | /* attempt to share read-only copies of mapped file chunks */ |
1100 | vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; |
1101 | if (file && !(prot & PROT_WRITE)) |
1102 | vm_flags |= VM_MAYSHARE; |
1103 | } else { |
1104 | /* overlay a shareable mapping on the backing device or inode |
1105 | * if possible - used for chardevs, ramfs/tmpfs/shmfs and |
1106 | * romfs/cramfs */ |
1107 | vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); |
1108 | if (flags & MAP_SHARED) |
1109 | vm_flags |= VM_SHARED; |
1110 | } |
1111 | |
1112 | /* refuse to let anyone share private mappings with this process if |
1113 | * it's being traced - otherwise breakpoints set in it may interfere |
1114 | * with another untraced process |
1115 | */ |
1116 | if ((flags & MAP_PRIVATE) && current->ptrace) |
1117 | vm_flags &= ~VM_MAYSHARE; |
1118 | |
1119 | return vm_flags; |
1120 | } |
1121 | |
1122 | /* |
1123 | * set up a shared mapping on a file (the driver or filesystem provides and |
1124 | * pins the storage) |
1125 | */ |
1126 | static int do_mmap_shared_file(struct vm_area_struct *vma) |
1127 | { |
1128 | int ret; |
1129 | |
1130 | ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); |
1131 | if (ret == 0) { |
1132 | vma->vm_region->vm_top = vma->vm_region->vm_end; |
1133 | return 0; |
1134 | } |
1135 | if (ret != -ENOSYS) |
1136 | return ret; |
1137 | |
1138 | /* getting -ENOSYS indicates that direct mmap isn't possible (as |
1139 | * opposed to tried but failed) so we can only give a suitable error as |
1140 | * it's not possible to make a private copy if MAP_SHARED was given */ |
1141 | return -ENODEV; |
1142 | } |
1143 | |
1144 | /* |
1145 | * set up a private mapping or an anonymous shared mapping |
1146 | */ |
1147 | static int do_mmap_private(struct vm_area_struct *vma, |
1148 | struct vm_region *region, |
1149 | unsigned long len, |
1150 | unsigned long capabilities) |
1151 | { |
1152 | struct page *pages; |
1153 | unsigned long total, point, n; |
1154 | void *base; |
1155 | int ret, order; |
1156 | |
1157 | /* invoke the file's mapping function so that it can keep track of |
1158 | * shared mappings on devices or memory |
1159 | * - VM_MAYSHARE will be set if it may attempt to share |
1160 | */ |
1161 | if (capabilities & BDI_CAP_MAP_DIRECT) { |
1162 | ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); |
1163 | if (ret == 0) { |
1164 | /* shouldn't return success if we're not sharing */ |
1165 | BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); |
1166 | vma->vm_region->vm_top = vma->vm_region->vm_end; |
1167 | return 0; |
1168 | } |
1169 | if (ret != -ENOSYS) |
1170 | return ret; |
1171 | |
1172 | /* getting an ENOSYS error indicates that direct mmap isn't |
1173 | * possible (as opposed to tried but failed) so we'll try to |
1174 | * make a private copy of the data and map that instead */ |
1175 | } |
1176 | |
1177 | |
1178 | /* allocate some memory to hold the mapping |
1179 | * - note that this may not return a page-aligned address if the object |
1180 | * we're allocating is smaller than a page |
1181 | */ |
1182 | order = get_order(len); |
1183 | kdebug("alloc order %d for %lx", order, len); |
1184 | |
1185 | pages = alloc_pages(GFP_KERNEL, order); |
1186 | if (!pages) |
1187 | goto enomem; |
1188 | |
1189 | total = 1 << order; |
1190 | atomic_long_add(total, &mmap_pages_allocated); |
1191 | |
1192 | point = len >> PAGE_SHIFT; |
1193 | |
1194 | /* we allocated a power-of-2 sized page set, so we may want to trim off |
1195 | * the excess */ |
1196 | if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { |
1197 | while (total > point) { |
1198 | order = ilog2(total - point); |
1199 | n = 1 << order; |
1200 | kdebug("shave %lu/%lu @%lu", n, total - point, total); |
1201 | atomic_long_sub(n, &mmap_pages_allocated); |
1202 | total -= n; |
1203 | set_page_refcounted(pages + total); |
1204 | __free_pages(pages + total, order); |
1205 | } |
1206 | } |
1207 | |
1208 | for (point = 1; point < total; point++) |
1209 | set_page_refcounted(&pages[point]); |
1210 | |
1211 | base = page_address(pages); |
1212 | region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; |
1213 | region->vm_start = (unsigned long) base; |
1214 | region->vm_end = region->vm_start + len; |
1215 | region->vm_top = region->vm_start + (total << PAGE_SHIFT); |
1216 | |
1217 | vma->vm_start = region->vm_start; |
1218 | vma->vm_end = region->vm_start + len; |
1219 | |
1220 | if (vma->vm_file) { |
1221 | /* read the contents of a file into the copy */ |
1222 | mm_segment_t old_fs; |
1223 | loff_t fpos; |
1224 | |
1225 | fpos = vma->vm_pgoff; |
1226 | fpos <<= PAGE_SHIFT; |
1227 | |
1228 | old_fs = get_fs(); |
1229 | set_fs(KERNEL_DS); |
1230 | ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); |
1231 | set_fs(old_fs); |
1232 | |
1233 | if (ret < 0) |
1234 | goto error_free; |
1235 | |
1236 | /* clear the last little bit */ |
1237 | if (ret < len) |
1238 | memset(base + ret, 0, len - ret); |
1239 | |
1240 | } |
1241 | |
1242 | return 0; |
1243 | |
1244 | error_free: |
1245 | free_page_series(region->vm_start, region->vm_top); |
1246 | region->vm_start = vma->vm_start = 0; |
1247 | region->vm_end = vma->vm_end = 0; |
1248 | region->vm_top = 0; |
1249 | return ret; |
1250 | |
1251 | enomem: |
1252 | pr_err("Allocation of length %lu from process %d (%s) failed\n", |
1253 | len, current->pid, current->comm); |
1254 | show_free_areas(0); |
1255 | return -ENOMEM; |
1256 | } |
1257 | |
1258 | /* |
1259 | * handle mapping creation for uClinux |
1260 | */ |
1261 | unsigned long do_mmap_pgoff(struct file *file, |
1262 | unsigned long addr, |
1263 | unsigned long len, |
1264 | unsigned long prot, |
1265 | unsigned long flags, |
1266 | unsigned long pgoff, |
1267 | unsigned long *populate) |
1268 | { |
1269 | struct vm_area_struct *vma; |
1270 | struct vm_region *region; |
1271 | struct rb_node *rb; |
1272 | unsigned long capabilities, vm_flags, result; |
1273 | int ret; |
1274 | |
1275 | kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); |
1276 | |
1277 | *populate = 0; |
1278 | |
1279 | /* decide whether we should attempt the mapping, and if so what sort of |
1280 | * mapping */ |
1281 | ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, |
1282 | &capabilities); |
1283 | if (ret < 0) { |
1284 | kleave(" = %d [val]", ret); |
1285 | return ret; |
1286 | } |
1287 | |
1288 | /* we ignore the address hint */ |
1289 | addr = 0; |
1290 | len = PAGE_ALIGN(len); |
1291 | |
1292 | /* we've determined that we can make the mapping, now translate what we |
1293 | * now know into VMA flags */ |
1294 | vm_flags = determine_vm_flags(file, prot, flags, capabilities); |
1295 | |
1296 | /* we're going to need to record the mapping */ |
1297 | region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); |
1298 | if (!region) |
1299 | goto error_getting_region; |
1300 | |
1301 | vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); |
1302 | if (!vma) |
1303 | goto error_getting_vma; |
1304 | |
1305 | region->vm_usage = 1; |
1306 | region->vm_flags = vm_flags; |
1307 | region->vm_pgoff = pgoff; |
1308 | |
1309 | INIT_LIST_HEAD(&vma->anon_vma_chain); |
1310 | vma->vm_flags = vm_flags; |
1311 | vma->vm_pgoff = pgoff; |
1312 | |
1313 | if (file) { |
1314 | region->vm_file = get_file(file); |
1315 | vma->vm_file = get_file(file); |
1316 | } |
1317 | |
1318 | down_write(&nommu_region_sem); |
1319 | |
1320 | /* if we want to share, we need to check for regions created by other |
1321 | * mmap() calls that overlap with our proposed mapping |
1322 | * - we can only share with a superset match on most regular files |
1323 | * - shared mappings on character devices and memory backed files are |
1324 | * permitted to overlap inexactly as far as we are concerned for in |
1325 | * these cases, sharing is handled in the driver or filesystem rather |
1326 | * than here |
1327 | */ |
1328 | if (vm_flags & VM_MAYSHARE) { |
1329 | struct vm_region *pregion; |
1330 | unsigned long pglen, rpglen, pgend, rpgend, start; |
1331 | |
1332 | pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1333 | pgend = pgoff + pglen; |
1334 | |
1335 | for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { |
1336 | pregion = rb_entry(rb, struct vm_region, vm_rb); |
1337 | |
1338 | if (!(pregion->vm_flags & VM_MAYSHARE)) |
1339 | continue; |
1340 | |
1341 | /* search for overlapping mappings on the same file */ |
1342 | if (file_inode(pregion->vm_file) != |
1343 | file_inode(file)) |
1344 | continue; |
1345 | |
1346 | if (pregion->vm_pgoff >= pgend) |
1347 | continue; |
1348 | |
1349 | rpglen = pregion->vm_end - pregion->vm_start; |
1350 | rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; |
1351 | rpgend = pregion->vm_pgoff + rpglen; |
1352 | if (pgoff >= rpgend) |
1353 | continue; |
1354 | |
1355 | /* handle inexactly overlapping matches between |
1356 | * mappings */ |
1357 | if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && |
1358 | !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { |
1359 | /* new mapping is not a subset of the region */ |
1360 | if (!(capabilities & BDI_CAP_MAP_DIRECT)) |
1361 | goto sharing_violation; |
1362 | continue; |
1363 | } |
1364 | |
1365 | /* we've found a region we can share */ |
1366 | pregion->vm_usage++; |
1367 | vma->vm_region = pregion; |
1368 | start = pregion->vm_start; |
1369 | start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; |
1370 | vma->vm_start = start; |
1371 | vma->vm_end = start + len; |
1372 | |
1373 | if (pregion->vm_flags & VM_MAPPED_COPY) { |
1374 | kdebug("share copy"); |
1375 | vma->vm_flags |= VM_MAPPED_COPY; |
1376 | } else { |
1377 | kdebug("share mmap"); |
1378 | ret = do_mmap_shared_file(vma); |
1379 | if (ret < 0) { |
1380 | vma->vm_region = NULL; |
1381 | vma->vm_start = 0; |
1382 | vma->vm_end = 0; |
1383 | pregion->vm_usage--; |
1384 | pregion = NULL; |
1385 | goto error_just_free; |
1386 | } |
1387 | } |
1388 | fput(region->vm_file); |
1389 | kmem_cache_free(vm_region_jar, region); |
1390 | region = pregion; |
1391 | result = start; |
1392 | goto share; |
1393 | } |
1394 | |
1395 | /* obtain the address at which to make a shared mapping |
1396 | * - this is the hook for quasi-memory character devices to |
1397 | * tell us the location of a shared mapping |
1398 | */ |
1399 | if (capabilities & BDI_CAP_MAP_DIRECT) { |
1400 | addr = file->f_op->get_unmapped_area(file, addr, len, |
1401 | pgoff, flags); |
1402 | if (IS_ERR_VALUE(addr)) { |
1403 | ret = addr; |
1404 | if (ret != -ENOSYS) |
1405 | goto error_just_free; |
1406 | |
1407 | /* the driver refused to tell us where to site |
1408 | * the mapping so we'll have to attempt to copy |
1409 | * it */ |
1410 | ret = -ENODEV; |
1411 | if (!(capabilities & BDI_CAP_MAP_COPY)) |
1412 | goto error_just_free; |
1413 | |
1414 | capabilities &= ~BDI_CAP_MAP_DIRECT; |
1415 | } else { |
1416 | vma->vm_start = region->vm_start = addr; |
1417 | vma->vm_end = region->vm_end = addr + len; |
1418 | } |
1419 | } |
1420 | } |
1421 | |
1422 | vma->vm_region = region; |
1423 | |
1424 | /* set up the mapping |
1425 | * - the region is filled in if BDI_CAP_MAP_DIRECT is still set |
1426 | */ |
1427 | if (file && vma->vm_flags & VM_SHARED) |
1428 | ret = do_mmap_shared_file(vma); |
1429 | else |
1430 | ret = do_mmap_private(vma, region, len, capabilities); |
1431 | if (ret < 0) |
1432 | goto error_just_free; |
1433 | add_nommu_region(region); |
1434 | |
1435 | /* clear anonymous mappings that don't ask for uninitialized data */ |
1436 | if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) |
1437 | memset((void *)region->vm_start, 0, |
1438 | region->vm_end - region->vm_start); |
1439 | |
1440 | /* okay... we have a mapping; now we have to register it */ |
1441 | result = vma->vm_start; |
1442 | |
1443 | current->mm->total_vm += len >> PAGE_SHIFT; |
1444 | |
1445 | share: |
1446 | add_vma_to_mm(current->mm, vma); |
1447 | |
1448 | /* we flush the region from the icache only when the first executable |
1449 | * mapping of it is made */ |
1450 | if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { |
1451 | flush_icache_range(region->vm_start, region->vm_end); |
1452 | region->vm_icache_flushed = true; |
1453 | } |
1454 | |
1455 | up_write(&nommu_region_sem); |
1456 | |
1457 | kleave(" = %lx", result); |
1458 | return result; |
1459 | |
1460 | error_just_free: |
1461 | up_write(&nommu_region_sem); |
1462 | error: |
1463 | if (region->vm_file) |
1464 | fput(region->vm_file); |
1465 | kmem_cache_free(vm_region_jar, region); |
1466 | if (vma->vm_file) |
1467 | fput(vma->vm_file); |
1468 | kmem_cache_free(vm_area_cachep, vma); |
1469 | kleave(" = %d", ret); |
1470 | return ret; |
1471 | |
1472 | sharing_violation: |
1473 | up_write(&nommu_region_sem); |
1474 | printk(KERN_WARNING "Attempt to share mismatched mappings\n"); |
1475 | ret = -EINVAL; |
1476 | goto error; |
1477 | |
1478 | error_getting_vma: |
1479 | kmem_cache_free(vm_region_jar, region); |
1480 | printk(KERN_WARNING "Allocation of vma for %lu byte allocation" |
1481 | " from process %d failed\n", |
1482 | len, current->pid); |
1483 | show_free_areas(0); |
1484 | return -ENOMEM; |
1485 | |
1486 | error_getting_region: |
1487 | printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" |
1488 | " from process %d failed\n", |
1489 | len, current->pid); |
1490 | show_free_areas(0); |
1491 | return -ENOMEM; |
1492 | } |
1493 | |
1494 | SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, |
1495 | unsigned long, prot, unsigned long, flags, |
1496 | unsigned long, fd, unsigned long, pgoff) |
1497 | { |
1498 | struct file *file = NULL; |
1499 | unsigned long retval = -EBADF; |
1500 | |
1501 | audit_mmap_fd(fd, flags); |
1502 | if (!(flags & MAP_ANONYMOUS)) { |
1503 | file = fget(fd); |
1504 | if (!file) |
1505 | goto out; |
1506 | } |
1507 | |
1508 | flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); |
1509 | |
1510 | retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); |
1511 | |
1512 | if (file) |
1513 | fput(file); |
1514 | out: |
1515 | return retval; |
1516 | } |
1517 | |
1518 | #ifdef __ARCH_WANT_SYS_OLD_MMAP |
1519 | struct mmap_arg_struct { |
1520 | unsigned long addr; |
1521 | unsigned long len; |
1522 | unsigned long prot; |
1523 | unsigned long flags; |
1524 | unsigned long fd; |
1525 | unsigned long offset; |
1526 | }; |
1527 | |
1528 | SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) |
1529 | { |
1530 | struct mmap_arg_struct a; |
1531 | |
1532 | if (copy_from_user(&a, arg, sizeof(a))) |
1533 | return -EFAULT; |
1534 | if (a.offset & ~PAGE_MASK) |
1535 | return -EINVAL; |
1536 | |
1537 | return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, |
1538 | a.offset >> PAGE_SHIFT); |
1539 | } |
1540 | #endif /* __ARCH_WANT_SYS_OLD_MMAP */ |
1541 | |
1542 | /* |
1543 | * split a vma into two pieces at address 'addr', a new vma is allocated either |
1544 | * for the first part or the tail. |
1545 | */ |
1546 | int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, |
1547 | unsigned long addr, int new_below) |
1548 | { |
1549 | struct vm_area_struct *new; |
1550 | struct vm_region *region; |
1551 | unsigned long npages; |
1552 | |
1553 | kenter(""); |
1554 | |
1555 | /* we're only permitted to split anonymous regions (these should have |
1556 | * only a single usage on the region) */ |
1557 | if (vma->vm_file) |
1558 | return -ENOMEM; |
1559 | |
1560 | if (mm->map_count >= sysctl_max_map_count) |
1561 | return -ENOMEM; |
1562 | |
1563 | region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); |
1564 | if (!region) |
1565 | return -ENOMEM; |
1566 | |
1567 | new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); |
1568 | if (!new) { |
1569 | kmem_cache_free(vm_region_jar, region); |
1570 | return -ENOMEM; |
1571 | } |
1572 | |
1573 | /* most fields are the same, copy all, and then fixup */ |
1574 | *new = *vma; |
1575 | *region = *vma->vm_region; |
1576 | new->vm_region = region; |
1577 | |
1578 | npages = (addr - vma->vm_start) >> PAGE_SHIFT; |
1579 | |
1580 | if (new_below) { |
1581 | region->vm_top = region->vm_end = new->vm_end = addr; |
1582 | } else { |
1583 | region->vm_start = new->vm_start = addr; |
1584 | region->vm_pgoff = new->vm_pgoff += npages; |
1585 | } |
1586 | |
1587 | if (new->vm_ops && new->vm_ops->open) |
1588 | new->vm_ops->open(new); |
1589 | |
1590 | delete_vma_from_mm(vma); |
1591 | down_write(&nommu_region_sem); |
1592 | delete_nommu_region(vma->vm_region); |
1593 | if (new_below) { |
1594 | vma->vm_region->vm_start = vma->vm_start = addr; |
1595 | vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; |
1596 | } else { |
1597 | vma->vm_region->vm_end = vma->vm_end = addr; |
1598 | vma->vm_region->vm_top = addr; |
1599 | } |
1600 | add_nommu_region(vma->vm_region); |
1601 | add_nommu_region(new->vm_region); |
1602 | up_write(&nommu_region_sem); |
1603 | add_vma_to_mm(mm, vma); |
1604 | add_vma_to_mm(mm, new); |
1605 | return 0; |
1606 | } |
1607 | |
1608 | /* |
1609 | * shrink a VMA by removing the specified chunk from either the beginning or |
1610 | * the end |
1611 | */ |
1612 | static int shrink_vma(struct mm_struct *mm, |
1613 | struct vm_area_struct *vma, |
1614 | unsigned long from, unsigned long to) |
1615 | { |
1616 | struct vm_region *region; |
1617 | |
1618 | kenter(""); |
1619 | |
1620 | /* adjust the VMA's pointers, which may reposition it in the MM's tree |
1621 | * and list */ |
1622 | delete_vma_from_mm(vma); |
1623 | if (from > vma->vm_start) |
1624 | vma->vm_end = from; |
1625 | else |
1626 | vma->vm_start = to; |
1627 | add_vma_to_mm(mm, vma); |
1628 | |
1629 | /* cut the backing region down to size */ |
1630 | region = vma->vm_region; |
1631 | BUG_ON(region->vm_usage != 1); |
1632 | |
1633 | down_write(&nommu_region_sem); |
1634 | delete_nommu_region(region); |
1635 | if (from > region->vm_start) { |
1636 | to = region->vm_top; |
1637 | region->vm_top = region->vm_end = from; |
1638 | } else { |
1639 | region->vm_start = to; |
1640 | } |
1641 | add_nommu_region(region); |
1642 | up_write(&nommu_region_sem); |
1643 | |
1644 | free_page_series(from, to); |
1645 | return 0; |
1646 | } |
1647 | |
1648 | /* |
1649 | * release a mapping |
1650 | * - under NOMMU conditions the chunk to be unmapped must be backed by a single |
1651 | * VMA, though it need not cover the whole VMA |
1652 | */ |
1653 | int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) |
1654 | { |
1655 | struct vm_area_struct *vma; |
1656 | unsigned long end; |
1657 | int ret; |
1658 | |
1659 | kenter(",%lx,%zx", start, len); |
1660 | |
1661 | len = PAGE_ALIGN(len); |
1662 | if (len == 0) |
1663 | return -EINVAL; |
1664 | |
1665 | end = start + len; |
1666 | |
1667 | /* find the first potentially overlapping VMA */ |
1668 | vma = find_vma(mm, start); |
1669 | if (!vma) { |
1670 | static int limit; |
1671 | if (limit < 5) { |
1672 | printk(KERN_WARNING |
1673 | "munmap of memory not mmapped by process %d" |
1674 | " (%s): 0x%lx-0x%lx\n", |
1675 | current->pid, current->comm, |
1676 | start, start + len - 1); |
1677 | limit++; |
1678 | } |
1679 | return -EINVAL; |
1680 | } |
1681 | |
1682 | /* we're allowed to split an anonymous VMA but not a file-backed one */ |
1683 | if (vma->vm_file) { |
1684 | do { |
1685 | if (start > vma->vm_start) { |
1686 | kleave(" = -EINVAL [miss]"); |
1687 | return -EINVAL; |
1688 | } |
1689 | if (end == vma->vm_end) |
1690 | goto erase_whole_vma; |
1691 | vma = vma->vm_next; |
1692 | } while (vma); |
1693 | kleave(" = -EINVAL [split file]"); |
1694 | return -EINVAL; |
1695 | } else { |
1696 | /* the chunk must be a subset of the VMA found */ |
1697 | if (start == vma->vm_start && end == vma->vm_end) |
1698 | goto erase_whole_vma; |
1699 | if (start < vma->vm_start || end > vma->vm_end) { |
1700 | kleave(" = -EINVAL [superset]"); |
1701 | return -EINVAL; |
1702 | } |
1703 | if (start & ~PAGE_MASK) { |
1704 | kleave(" = -EINVAL [unaligned start]"); |
1705 | return -EINVAL; |
1706 | } |
1707 | if (end != vma->vm_end && end & ~PAGE_MASK) { |
1708 | kleave(" = -EINVAL [unaligned split]"); |
1709 | return -EINVAL; |
1710 | } |
1711 | if (start != vma->vm_start && end != vma->vm_end) { |
1712 | ret = split_vma(mm, vma, start, 1); |
1713 | if (ret < 0) { |
1714 | kleave(" = %d [split]", ret); |
1715 | return ret; |
1716 | } |
1717 | } |
1718 | return shrink_vma(mm, vma, start, end); |
1719 | } |
1720 | |
1721 | erase_whole_vma: |
1722 | delete_vma_from_mm(vma); |
1723 | delete_vma(mm, vma); |
1724 | kleave(" = 0"); |
1725 | return 0; |
1726 | } |
1727 | EXPORT_SYMBOL(do_munmap); |
1728 | |
1729 | int vm_munmap(unsigned long addr, size_t len) |
1730 | { |
1731 | struct mm_struct *mm = current->mm; |
1732 | int ret; |
1733 | |
1734 | down_write(&mm->mmap_sem); |
1735 | ret = do_munmap(mm, addr, len); |
1736 | up_write(&mm->mmap_sem); |
1737 | return ret; |
1738 | } |
1739 | EXPORT_SYMBOL(vm_munmap); |
1740 | |
1741 | SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) |
1742 | { |
1743 | return vm_munmap(addr, len); |
1744 | } |
1745 | |
1746 | /* |
1747 | * release all the mappings made in a process's VM space |
1748 | */ |
1749 | void exit_mmap(struct mm_struct *mm) |
1750 | { |
1751 | struct vm_area_struct *vma; |
1752 | |
1753 | if (!mm) |
1754 | return; |
1755 | |
1756 | kenter(""); |
1757 | |
1758 | mm->total_vm = 0; |
1759 | |
1760 | while ((vma = mm->mmap)) { |
1761 | mm->mmap = vma->vm_next; |
1762 | delete_vma_from_mm(vma); |
1763 | delete_vma(mm, vma); |
1764 | cond_resched(); |
1765 | } |
1766 | |
1767 | kleave(""); |
1768 | } |
1769 | |
1770 | unsigned long vm_brk(unsigned long addr, unsigned long len) |
1771 | { |
1772 | return -ENOMEM; |
1773 | } |
1774 | |
1775 | /* |
1776 | * expand (or shrink) an existing mapping, potentially moving it at the same |
1777 | * time (controlled by the MREMAP_MAYMOVE flag and available VM space) |
1778 | * |
1779 | * under NOMMU conditions, we only permit changing a mapping's size, and only |
1780 | * as long as it stays within the region allocated by do_mmap_private() and the |
1781 | * block is not shareable |
1782 | * |
1783 | * MREMAP_FIXED is not supported under NOMMU conditions |
1784 | */ |
1785 | static unsigned long do_mremap(unsigned long addr, |
1786 | unsigned long old_len, unsigned long new_len, |
1787 | unsigned long flags, unsigned long new_addr) |
1788 | { |
1789 | struct vm_area_struct *vma; |
1790 | |
1791 | /* insanity checks first */ |
1792 | old_len = PAGE_ALIGN(old_len); |
1793 | new_len = PAGE_ALIGN(new_len); |
1794 | if (old_len == 0 || new_len == 0) |
1795 | return (unsigned long) -EINVAL; |
1796 | |
1797 | if (addr & ~PAGE_MASK) |
1798 | return -EINVAL; |
1799 | |
1800 | if (flags & MREMAP_FIXED && new_addr != addr) |
1801 | return (unsigned long) -EINVAL; |
1802 | |
1803 | vma = find_vma_exact(current->mm, addr, old_len); |
1804 | if (!vma) |
1805 | return (unsigned long) -EINVAL; |
1806 | |
1807 | if (vma->vm_end != vma->vm_start + old_len) |
1808 | return (unsigned long) -EFAULT; |
1809 | |
1810 | if (vma->vm_flags & VM_MAYSHARE) |
1811 | return (unsigned long) -EPERM; |
1812 | |
1813 | if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) |
1814 | return (unsigned long) -ENOMEM; |
1815 | |
1816 | /* all checks complete - do it */ |
1817 | vma->vm_end = vma->vm_start + new_len; |
1818 | return vma->vm_start; |
1819 | } |
1820 | |
1821 | SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, |
1822 | unsigned long, new_len, unsigned long, flags, |
1823 | unsigned long, new_addr) |
1824 | { |
1825 | unsigned long ret; |
1826 | |
1827 | down_write(¤t->mm->mmap_sem); |
1828 | ret = do_mremap(addr, old_len, new_len, flags, new_addr); |
1829 | up_write(¤t->mm->mmap_sem); |
1830 | return ret; |
1831 | } |
1832 | |
1833 | struct page *follow_page_mask(struct vm_area_struct *vma, |
1834 | unsigned long address, unsigned int flags, |
1835 | unsigned int *page_mask) |
1836 | { |
1837 | *page_mask = 0; |
1838 | return NULL; |
1839 | } |
1840 | |
1841 | int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, |
1842 | unsigned long pfn, unsigned long size, pgprot_t prot) |
1843 | { |
1844 | if (addr != (pfn << PAGE_SHIFT)) |
1845 | return -EINVAL; |
1846 | |
1847 | vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; |
1848 | return 0; |
1849 | } |
1850 | EXPORT_SYMBOL(remap_pfn_range); |
1851 | |
1852 | int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) |
1853 | { |
1854 | unsigned long pfn = start >> PAGE_SHIFT; |
1855 | unsigned long vm_len = vma->vm_end - vma->vm_start; |
1856 | |
1857 | pfn += vma->vm_pgoff; |
1858 | return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); |
1859 | } |
1860 | EXPORT_SYMBOL(vm_iomap_memory); |
1861 | |
1862 | int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, |
1863 | unsigned long pgoff) |
1864 | { |
1865 | unsigned int size = vma->vm_end - vma->vm_start; |
1866 | |
1867 | if (!(vma->vm_flags & VM_USERMAP)) |
1868 | return -EINVAL; |
1869 | |
1870 | vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); |
1871 | vma->vm_end = vma->vm_start + size; |
1872 | |
1873 | return 0; |
1874 | } |
1875 | EXPORT_SYMBOL(remap_vmalloc_range); |
1876 | |
1877 | unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, |
1878 | unsigned long len, unsigned long pgoff, unsigned long flags) |
1879 | { |
1880 | return -ENOMEM; |
1881 | } |
1882 | |
1883 | void unmap_mapping_range(struct address_space *mapping, |
1884 | loff_t const holebegin, loff_t const holelen, |
1885 | int even_cows) |
1886 | { |
1887 | } |
1888 | EXPORT_SYMBOL(unmap_mapping_range); |
1889 | |
1890 | /* |
1891 | * Check that a process has enough memory to allocate a new virtual |
1892 | * mapping. 0 means there is enough memory for the allocation to |
1893 | * succeed and -ENOMEM implies there is not. |
1894 | * |
1895 | * We currently support three overcommit policies, which are set via the |
1896 | * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting |
1897 | * |
1898 | * Strict overcommit modes added 2002 Feb 26 by Alan Cox. |
1899 | * Additional code 2002 Jul 20 by Robert Love. |
1900 | * |
1901 | * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. |
1902 | * |
1903 | * Note this is a helper function intended to be used by LSMs which |
1904 | * wish to use this logic. |
1905 | */ |
1906 | int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) |
1907 | { |
1908 | unsigned long free, allowed, reserve; |
1909 | |
1910 | vm_acct_memory(pages); |
1911 | |
1912 | /* |
1913 | * Sometimes we want to use more memory than we have |
1914 | */ |
1915 | if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) |
1916 | return 0; |
1917 | |
1918 | if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { |
1919 | free = global_page_state(NR_FREE_PAGES); |
1920 | free += global_page_state(NR_FILE_PAGES); |
1921 | |
1922 | /* |
1923 | * shmem pages shouldn't be counted as free in this |
1924 | * case, they can't be purged, only swapped out, and |
1925 | * that won't affect the overall amount of available |
1926 | * memory in the system. |
1927 | */ |
1928 | free -= global_page_state(NR_SHMEM); |
1929 | |
1930 | free += get_nr_swap_pages(); |
1931 | |
1932 | /* |
1933 | * Any slabs which are created with the |
1934 | * SLAB_RECLAIM_ACCOUNT flag claim to have contents |
1935 | * which are reclaimable, under pressure. The dentry |
1936 | * cache and most inode caches should fall into this |
1937 | */ |
1938 | free += global_page_state(NR_SLAB_RECLAIMABLE); |
1939 | |
1940 | /* |
1941 | * Leave reserved pages. The pages are not for anonymous pages. |
1942 | */ |
1943 | if (free <= totalreserve_pages) |
1944 | goto error; |
1945 | else |
1946 | free -= totalreserve_pages; |
1947 | |
1948 | /* |
1949 | * Reserve some for root |
1950 | */ |
1951 | if (!cap_sys_admin) |
1952 | free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); |
1953 | |
1954 | if (free > pages) |
1955 | return 0; |
1956 | |
1957 | goto error; |
1958 | } |
1959 | |
1960 | allowed = vm_commit_limit(); |
1961 | /* |
1962 | * Reserve some 3% for root |
1963 | */ |
1964 | if (!cap_sys_admin) |
1965 | allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10); |
1966 | |
1967 | /* |
1968 | * Don't let a single process grow so big a user can't recover |
1969 | */ |
1970 | if (mm) { |
1971 | reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10); |
1972 | allowed -= min(mm->total_vm / 32, reserve); |
1973 | } |
1974 | |
1975 | if (percpu_counter_read_positive(&vm_committed_as) < allowed) |
1976 | return 0; |
1977 | |
1978 | error: |
1979 | vm_unacct_memory(pages); |
1980 | |
1981 | return -ENOMEM; |
1982 | } |
1983 | |
1984 | int in_gate_area_no_mm(unsigned long addr) |
1985 | { |
1986 | return 0; |
1987 | } |
1988 | |
1989 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) |
1990 | { |
1991 | BUG(); |
1992 | return 0; |
1993 | } |
1994 | EXPORT_SYMBOL(filemap_fault); |
1995 | |
1996 | void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf) |
1997 | { |
1998 | BUG(); |
1999 | } |
2000 | EXPORT_SYMBOL(filemap_map_pages); |
2001 | |
2002 | int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr, |
2003 | unsigned long size, pgoff_t pgoff) |
2004 | { |
2005 | BUG(); |
2006 | return 0; |
2007 | } |
2008 | EXPORT_SYMBOL(generic_file_remap_pages); |
2009 | |
2010 | static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, |
2011 | unsigned long addr, void *buf, int len, int write) |
2012 | { |
2013 | struct vm_area_struct *vma; |
2014 | |
2015 | down_read(&mm->mmap_sem); |
2016 | |
2017 | /* the access must start within one of the target process's mappings */ |
2018 | vma = find_vma(mm, addr); |
2019 | if (vma) { |
2020 | /* don't overrun this mapping */ |
2021 | if (addr + len >= vma->vm_end) |
2022 | len = vma->vm_end - addr; |
2023 | |
2024 | /* only read or write mappings where it is permitted */ |
2025 | if (write && vma->vm_flags & VM_MAYWRITE) |
2026 | copy_to_user_page(vma, NULL, addr, |
2027 | (void *) addr, buf, len); |
2028 | else if (!write && vma->vm_flags & VM_MAYREAD) |
2029 | copy_from_user_page(vma, NULL, addr, |
2030 | buf, (void *) addr, len); |
2031 | else |
2032 | len = 0; |
2033 | } else { |
2034 | len = 0; |
2035 | } |
2036 | |
2037 | up_read(&mm->mmap_sem); |
2038 | |
2039 | return len; |
2040 | } |
2041 | |
2042 | /** |
2043 | * @access_remote_vm - access another process' address space |
2044 | * @mm: the mm_struct of the target address space |
2045 | * @addr: start address to access |
2046 | * @buf: source or destination buffer |
2047 | * @len: number of bytes to transfer |
2048 | * @write: whether the access is a write |
2049 | * |
2050 | * The caller must hold a reference on @mm. |
2051 | */ |
2052 | int access_remote_vm(struct mm_struct *mm, unsigned long addr, |
2053 | void *buf, int len, int write) |
2054 | { |
2055 | return __access_remote_vm(NULL, mm, addr, buf, len, write); |
2056 | } |
2057 | |
2058 | /* |
2059 | * Access another process' address space. |
2060 | * - source/target buffer must be kernel space |
2061 | */ |
2062 | int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) |
2063 | { |
2064 | struct mm_struct *mm; |
2065 | |
2066 | if (addr + len < addr) |
2067 | return 0; |
2068 | |
2069 | mm = get_task_mm(tsk); |
2070 | if (!mm) |
2071 | return 0; |
2072 | |
2073 | len = __access_remote_vm(tsk, mm, addr, buf, len, write); |
2074 | |
2075 | mmput(mm); |
2076 | return len; |
2077 | } |
2078 | |
2079 | /** |
2080 | * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode |
2081 | * @inode: The inode to check |
2082 | * @size: The current filesize of the inode |
2083 | * @newsize: The proposed filesize of the inode |
2084 | * |
2085 | * Check the shared mappings on an inode on behalf of a shrinking truncate to |
2086 | * make sure that that any outstanding VMAs aren't broken and then shrink the |
2087 | * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't |
2088 | * automatically grant mappings that are too large. |
2089 | */ |
2090 | int nommu_shrink_inode_mappings(struct inode *inode, size_t size, |
2091 | size_t newsize) |
2092 | { |
2093 | struct vm_area_struct *vma; |
2094 | struct vm_region *region; |
2095 | pgoff_t low, high; |
2096 | size_t r_size, r_top; |
2097 | |
2098 | low = newsize >> PAGE_SHIFT; |
2099 | high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; |
2100 | |
2101 | down_write(&nommu_region_sem); |
2102 | mutex_lock(&inode->i_mapping->i_mmap_mutex); |
2103 | |
2104 | /* search for VMAs that fall within the dead zone */ |
2105 | vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { |
2106 | /* found one - only interested if it's shared out of the page |
2107 | * cache */ |
2108 | if (vma->vm_flags & VM_SHARED) { |
2109 | mutex_unlock(&inode->i_mapping->i_mmap_mutex); |
2110 | up_write(&nommu_region_sem); |
2111 | return -ETXTBSY; /* not quite true, but near enough */ |
2112 | } |
2113 | } |
2114 | |
2115 | /* reduce any regions that overlap the dead zone - if in existence, |
2116 | * these will be pointed to by VMAs that don't overlap the dead zone |
2117 | * |
2118 | * we don't check for any regions that start beyond the EOF as there |
2119 | * shouldn't be any |
2120 | */ |
2121 | vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, |
2122 | 0, ULONG_MAX) { |
2123 | if (!(vma->vm_flags & VM_SHARED)) |
2124 | continue; |
2125 | |
2126 | region = vma->vm_region; |
2127 | r_size = region->vm_top - region->vm_start; |
2128 | r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; |
2129 | |
2130 | if (r_top > newsize) { |
2131 | region->vm_top -= r_top - newsize; |
2132 | if (region->vm_end > region->vm_top) |
2133 | region->vm_end = region->vm_top; |
2134 | } |
2135 | } |
2136 | |
2137 | mutex_unlock(&inode->i_mapping->i_mmap_mutex); |
2138 | up_write(&nommu_region_sem); |
2139 | return 0; |
2140 | } |
2141 | |
2142 | /* |
2143 | * Initialise sysctl_user_reserve_kbytes. |
2144 | * |
2145 | * This is intended to prevent a user from starting a single memory hogging |
2146 | * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER |
2147 | * mode. |
2148 | * |
2149 | * The default value is min(3% of free memory, 128MB) |
2150 | * 128MB is enough to recover with sshd/login, bash, and top/kill. |
2151 | */ |
2152 | static int __meminit init_user_reserve(void) |
2153 | { |
2154 | unsigned long free_kbytes; |
2155 | |
2156 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
2157 | |
2158 | sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); |
2159 | return 0; |
2160 | } |
2161 | module_init(init_user_reserve) |
2162 | |
2163 | /* |
2164 | * Initialise sysctl_admin_reserve_kbytes. |
2165 | * |
2166 | * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin |
2167 | * to log in and kill a memory hogging process. |
2168 | * |
2169 | * Systems with more than 256MB will reserve 8MB, enough to recover |
2170 | * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will |
2171 | * only reserve 3% of free pages by default. |
2172 | */ |
2173 | static int __meminit init_admin_reserve(void) |
2174 | { |
2175 | unsigned long free_kbytes; |
2176 | |
2177 | free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); |
2178 | |
2179 | sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); |
2180 | return 0; |
2181 | } |
2182 | module_init(init_admin_reserve) |
2183 |
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