xref: /openbmc/linux/mm/vmalloc.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
1 /*
2  *  linux/mm/vmalloc.c
3  *
4  *  Copyright (C) 1993  Linus Torvalds
5  *  Support of BIGMEM added by Gerhard Wichert, Siemens AG, July 1999
6  *  SMP-safe vmalloc/vfree/ioremap, Tigran Aivazian <tigran@veritas.com>, May 2000
7  *  Major rework to support vmap/vunmap, Christoph Hellwig, SGI, August 2002
8  *  Numa awareness, Christoph Lameter, SGI, June 2005
9  */
10 
11 #include <linux/mm.h>
12 #include <linux/module.h>
13 #include <linux/highmem.h>
14 #include <linux/slab.h>
15 #include <linux/spinlock.h>
16 #include <linux/interrupt.h>
17 
18 #include <linux/vmalloc.h>
19 
20 #include <asm/uaccess.h>
21 #include <asm/tlbflush.h>
22 
23 
24 DEFINE_RWLOCK(vmlist_lock);
25 struct vm_struct *vmlist;
26 
27 static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
28 			    int node);
29 
30 static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end)
31 {
32 	pte_t *pte;
33 
34 	pte = pte_offset_kernel(pmd, addr);
35 	do {
36 		pte_t ptent = ptep_get_and_clear(&init_mm, addr, pte);
37 		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
38 	} while (pte++, addr += PAGE_SIZE, addr != end);
39 }
40 
41 static inline void vunmap_pmd_range(pud_t *pud, unsigned long addr,
42 						unsigned long end)
43 {
44 	pmd_t *pmd;
45 	unsigned long next;
46 
47 	pmd = pmd_offset(pud, addr);
48 	do {
49 		next = pmd_addr_end(addr, end);
50 		if (pmd_none_or_clear_bad(pmd))
51 			continue;
52 		vunmap_pte_range(pmd, addr, next);
53 	} while (pmd++, addr = next, addr != end);
54 }
55 
56 static inline void vunmap_pud_range(pgd_t *pgd, unsigned long addr,
57 						unsigned long end)
58 {
59 	pud_t *pud;
60 	unsigned long next;
61 
62 	pud = pud_offset(pgd, addr);
63 	do {
64 		next = pud_addr_end(addr, end);
65 		if (pud_none_or_clear_bad(pud))
66 			continue;
67 		vunmap_pmd_range(pud, addr, next);
68 	} while (pud++, addr = next, addr != end);
69 }
70 
71 void unmap_vm_area(struct vm_struct *area)
72 {
73 	pgd_t *pgd;
74 	unsigned long next;
75 	unsigned long addr = (unsigned long) area->addr;
76 	unsigned long end = addr + area->size;
77 
78 	BUG_ON(addr >= end);
79 	pgd = pgd_offset_k(addr);
80 	flush_cache_vunmap(addr, end);
81 	do {
82 		next = pgd_addr_end(addr, end);
83 		if (pgd_none_or_clear_bad(pgd))
84 			continue;
85 		vunmap_pud_range(pgd, addr, next);
86 	} while (pgd++, addr = next, addr != end);
87 	flush_tlb_kernel_range((unsigned long) area->addr, end);
88 }
89 
90 static int vmap_pte_range(pmd_t *pmd, unsigned long addr,
91 			unsigned long end, pgprot_t prot, struct page ***pages)
92 {
93 	pte_t *pte;
94 
95 	pte = pte_alloc_kernel(pmd, addr);
96 	if (!pte)
97 		return -ENOMEM;
98 	do {
99 		struct page *page = **pages;
100 		WARN_ON(!pte_none(*pte));
101 		if (!page)
102 			return -ENOMEM;
103 		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
104 		(*pages)++;
105 	} while (pte++, addr += PAGE_SIZE, addr != end);
106 	return 0;
107 }
108 
109 static inline int vmap_pmd_range(pud_t *pud, unsigned long addr,
110 			unsigned long end, pgprot_t prot, struct page ***pages)
111 {
112 	pmd_t *pmd;
113 	unsigned long next;
114 
115 	pmd = pmd_alloc(&init_mm, pud, addr);
116 	if (!pmd)
117 		return -ENOMEM;
118 	do {
119 		next = pmd_addr_end(addr, end);
120 		if (vmap_pte_range(pmd, addr, next, prot, pages))
121 			return -ENOMEM;
122 	} while (pmd++, addr = next, addr != end);
123 	return 0;
124 }
125 
126 static inline int vmap_pud_range(pgd_t *pgd, unsigned long addr,
127 			unsigned long end, pgprot_t prot, struct page ***pages)
128 {
129 	pud_t *pud;
130 	unsigned long next;
131 
132 	pud = pud_alloc(&init_mm, pgd, addr);
133 	if (!pud)
134 		return -ENOMEM;
135 	do {
136 		next = pud_addr_end(addr, end);
137 		if (vmap_pmd_range(pud, addr, next, prot, pages))
138 			return -ENOMEM;
139 	} while (pud++, addr = next, addr != end);
140 	return 0;
141 }
142 
143 int map_vm_area(struct vm_struct *area, pgprot_t prot, struct page ***pages)
144 {
145 	pgd_t *pgd;
146 	unsigned long next;
147 	unsigned long addr = (unsigned long) area->addr;
148 	unsigned long end = addr + area->size - PAGE_SIZE;
149 	int err;
150 
151 	BUG_ON(addr >= end);
152 	pgd = pgd_offset_k(addr);
153 	do {
154 		next = pgd_addr_end(addr, end);
155 		err = vmap_pud_range(pgd, addr, next, prot, pages);
156 		if (err)
157 			break;
158 	} while (pgd++, addr = next, addr != end);
159 	flush_cache_vmap((unsigned long) area->addr, end);
160 	return err;
161 }
162 
163 static struct vm_struct *__get_vm_area_node(unsigned long size, unsigned long flags,
164 					    unsigned long start, unsigned long end,
165 					    int node, gfp_t gfp_mask)
166 {
167 	struct vm_struct **p, *tmp, *area;
168 	unsigned long align = 1;
169 	unsigned long addr;
170 
171 	BUG_ON(in_interrupt());
172 	if (flags & VM_IOREMAP) {
173 		int bit = fls(size);
174 
175 		if (bit > IOREMAP_MAX_ORDER)
176 			bit = IOREMAP_MAX_ORDER;
177 		else if (bit < PAGE_SHIFT)
178 			bit = PAGE_SHIFT;
179 
180 		align = 1ul << bit;
181 	}
182 	addr = ALIGN(start, align);
183 	size = PAGE_ALIGN(size);
184 	if (unlikely(!size))
185 		return NULL;
186 
187 	area = kmalloc_node(sizeof(*area), gfp_mask & GFP_LEVEL_MASK, node);
188 	if (unlikely(!area))
189 		return NULL;
190 
191 	/*
192 	 * We always allocate a guard page.
193 	 */
194 	size += PAGE_SIZE;
195 
196 	write_lock(&vmlist_lock);
197 	for (p = &vmlist; (tmp = *p) != NULL ;p = &tmp->next) {
198 		if ((unsigned long)tmp->addr < addr) {
199 			if((unsigned long)tmp->addr + tmp->size >= addr)
200 				addr = ALIGN(tmp->size +
201 					     (unsigned long)tmp->addr, align);
202 			continue;
203 		}
204 		if ((size + addr) < addr)
205 			goto out;
206 		if (size + addr <= (unsigned long)tmp->addr)
207 			goto found;
208 		addr = ALIGN(tmp->size + (unsigned long)tmp->addr, align);
209 		if (addr > end - size)
210 			goto out;
211 	}
212 
213 found:
214 	area->next = *p;
215 	*p = area;
216 
217 	area->flags = flags;
218 	area->addr = (void *)addr;
219 	area->size = size;
220 	area->pages = NULL;
221 	area->nr_pages = 0;
222 	area->phys_addr = 0;
223 	write_unlock(&vmlist_lock);
224 
225 	return area;
226 
227 out:
228 	write_unlock(&vmlist_lock);
229 	kfree(area);
230 	if (printk_ratelimit())
231 		printk(KERN_WARNING "allocation failed: out of vmalloc space - use vmalloc=<size> to increase size.\n");
232 	return NULL;
233 }
234 
235 struct vm_struct *__get_vm_area(unsigned long size, unsigned long flags,
236 				unsigned long start, unsigned long end)
237 {
238 	return __get_vm_area_node(size, flags, start, end, -1, GFP_KERNEL);
239 }
240 
241 /**
242  *	get_vm_area  -  reserve a contingous kernel virtual area
243  *	@size:		size of the area
244  *	@flags:		%VM_IOREMAP for I/O mappings or VM_ALLOC
245  *
246  *	Search an area of @size in the kernel virtual mapping area,
247  *	and reserved it for out purposes.  Returns the area descriptor
248  *	on success or %NULL on failure.
249  */
250 struct vm_struct *get_vm_area(unsigned long size, unsigned long flags)
251 {
252 	return __get_vm_area(size, flags, VMALLOC_START, VMALLOC_END);
253 }
254 
255 struct vm_struct *get_vm_area_node(unsigned long size, unsigned long flags,
256 				   int node, gfp_t gfp_mask)
257 {
258 	return __get_vm_area_node(size, flags, VMALLOC_START, VMALLOC_END, node,
259 				  gfp_mask);
260 }
261 
262 /* Caller must hold vmlist_lock */
263 static struct vm_struct *__find_vm_area(void *addr)
264 {
265 	struct vm_struct *tmp;
266 
267 	for (tmp = vmlist; tmp != NULL; tmp = tmp->next) {
268 		 if (tmp->addr == addr)
269 			break;
270 	}
271 
272 	return tmp;
273 }
274 
275 /* Caller must hold vmlist_lock */
276 static struct vm_struct *__remove_vm_area(void *addr)
277 {
278 	struct vm_struct **p, *tmp;
279 
280 	for (p = &vmlist ; (tmp = *p) != NULL ;p = &tmp->next) {
281 		 if (tmp->addr == addr)
282 			 goto found;
283 	}
284 	return NULL;
285 
286 found:
287 	unmap_vm_area(tmp);
288 	*p = tmp->next;
289 
290 	/*
291 	 * Remove the guard page.
292 	 */
293 	tmp->size -= PAGE_SIZE;
294 	return tmp;
295 }
296 
297 /**
298  *	remove_vm_area  -  find and remove a contingous kernel virtual area
299  *	@addr:		base address
300  *
301  *	Search for the kernel VM area starting at @addr, and remove it.
302  *	This function returns the found VM area, but using it is NOT safe
303  *	on SMP machines, except for its size or flags.
304  */
305 struct vm_struct *remove_vm_area(void *addr)
306 {
307 	struct vm_struct *v;
308 	write_lock(&vmlist_lock);
309 	v = __remove_vm_area(addr);
310 	write_unlock(&vmlist_lock);
311 	return v;
312 }
313 
314 void __vunmap(void *addr, int deallocate_pages)
315 {
316 	struct vm_struct *area;
317 
318 	if (!addr)
319 		return;
320 
321 	if ((PAGE_SIZE-1) & (unsigned long)addr) {
322 		printk(KERN_ERR "Trying to vfree() bad address (%p)\n", addr);
323 		WARN_ON(1);
324 		return;
325 	}
326 
327 	area = remove_vm_area(addr);
328 	if (unlikely(!area)) {
329 		printk(KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
330 				addr);
331 		WARN_ON(1);
332 		return;
333 	}
334 
335 	debug_check_no_locks_freed(addr, area->size);
336 
337 	if (deallocate_pages) {
338 		int i;
339 
340 		for (i = 0; i < area->nr_pages; i++) {
341 			BUG_ON(!area->pages[i]);
342 			__free_page(area->pages[i]);
343 		}
344 
345 		if (area->flags & VM_VPAGES)
346 			vfree(area->pages);
347 		else
348 			kfree(area->pages);
349 	}
350 
351 	kfree(area);
352 	return;
353 }
354 
355 /**
356  *	vfree  -  release memory allocated by vmalloc()
357  *	@addr:		memory base address
358  *
359  *	Free the virtually contiguous memory area starting at @addr, as
360  *	obtained from vmalloc(), vmalloc_32() or __vmalloc(). If @addr is
361  *	NULL, no operation is performed.
362  *
363  *	Must not be called in interrupt context.
364  */
365 void vfree(void *addr)
366 {
367 	BUG_ON(in_interrupt());
368 	__vunmap(addr, 1);
369 }
370 EXPORT_SYMBOL(vfree);
371 
372 /**
373  *	vunmap  -  release virtual mapping obtained by vmap()
374  *	@addr:		memory base address
375  *
376  *	Free the virtually contiguous memory area starting at @addr,
377  *	which was created from the page array passed to vmap().
378  *
379  *	Must not be called in interrupt context.
380  */
381 void vunmap(void *addr)
382 {
383 	BUG_ON(in_interrupt());
384 	__vunmap(addr, 0);
385 }
386 EXPORT_SYMBOL(vunmap);
387 
388 /**
389  *	vmap  -  map an array of pages into virtually contiguous space
390  *	@pages:		array of page pointers
391  *	@count:		number of pages to map
392  *	@flags:		vm_area->flags
393  *	@prot:		page protection for the mapping
394  *
395  *	Maps @count pages from @pages into contiguous kernel virtual
396  *	space.
397  */
398 void *vmap(struct page **pages, unsigned int count,
399 		unsigned long flags, pgprot_t prot)
400 {
401 	struct vm_struct *area;
402 
403 	if (count > num_physpages)
404 		return NULL;
405 
406 	area = get_vm_area((count << PAGE_SHIFT), flags);
407 	if (!area)
408 		return NULL;
409 	if (map_vm_area(area, prot, &pages)) {
410 		vunmap(area->addr);
411 		return NULL;
412 	}
413 
414 	return area->addr;
415 }
416 EXPORT_SYMBOL(vmap);
417 
418 void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
419 				pgprot_t prot, int node)
420 {
421 	struct page **pages;
422 	unsigned int nr_pages, array_size, i;
423 
424 	nr_pages = (area->size - PAGE_SIZE) >> PAGE_SHIFT;
425 	array_size = (nr_pages * sizeof(struct page *));
426 
427 	area->nr_pages = nr_pages;
428 	/* Please note that the recursion is strictly bounded. */
429 	if (array_size > PAGE_SIZE) {
430 		pages = __vmalloc_node(array_size, gfp_mask, PAGE_KERNEL, node);
431 		area->flags |= VM_VPAGES;
432 	} else {
433 		pages = kmalloc_node(array_size,
434 				(gfp_mask & GFP_LEVEL_MASK),
435 				node);
436 	}
437 	area->pages = pages;
438 	if (!area->pages) {
439 		remove_vm_area(area->addr);
440 		kfree(area);
441 		return NULL;
442 	}
443 	memset(area->pages, 0, array_size);
444 
445 	for (i = 0; i < area->nr_pages; i++) {
446 		if (node < 0)
447 			area->pages[i] = alloc_page(gfp_mask);
448 		else
449 			area->pages[i] = alloc_pages_node(node, gfp_mask, 0);
450 		if (unlikely(!area->pages[i])) {
451 			/* Successfully allocated i pages, free them in __vunmap() */
452 			area->nr_pages = i;
453 			goto fail;
454 		}
455 	}
456 
457 	if (map_vm_area(area, prot, &pages))
458 		goto fail;
459 	return area->addr;
460 
461 fail:
462 	vfree(area->addr);
463 	return NULL;
464 }
465 
466 void *__vmalloc_area(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot)
467 {
468 	return __vmalloc_area_node(area, gfp_mask, prot, -1);
469 }
470 
471 /**
472  *	__vmalloc_node  -  allocate virtually contiguous memory
473  *	@size:		allocation size
474  *	@gfp_mask:	flags for the page level allocator
475  *	@prot:		protection mask for the allocated pages
476  *	@node:		node to use for allocation or -1
477  *
478  *	Allocate enough pages to cover @size from the page level
479  *	allocator with @gfp_mask flags.  Map them into contiguous
480  *	kernel virtual space, using a pagetable protection of @prot.
481  */
482 static void *__vmalloc_node(unsigned long size, gfp_t gfp_mask, pgprot_t prot,
483 			    int node)
484 {
485 	struct vm_struct *area;
486 
487 	size = PAGE_ALIGN(size);
488 	if (!size || (size >> PAGE_SHIFT) > num_physpages)
489 		return NULL;
490 
491 	area = get_vm_area_node(size, VM_ALLOC, node, gfp_mask);
492 	if (!area)
493 		return NULL;
494 
495 	return __vmalloc_area_node(area, gfp_mask, prot, node);
496 }
497 
498 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
499 {
500 	return __vmalloc_node(size, gfp_mask, prot, -1);
501 }
502 EXPORT_SYMBOL(__vmalloc);
503 
504 /**
505  *	vmalloc  -  allocate virtually contiguous memory
506  *	@size:		allocation size
507  *	Allocate enough pages to cover @size from the page level
508  *	allocator and map them into contiguous kernel virtual space.
509  *
510  *	For tight control over page level allocator and protection flags
511  *	use __vmalloc() instead.
512  */
513 void *vmalloc(unsigned long size)
514 {
515 	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
516 }
517 EXPORT_SYMBOL(vmalloc);
518 
519 /**
520  * vmalloc_user - allocate zeroed virtually contiguous memory for userspace
521  * @size: allocation size
522  *
523  * The resulting memory area is zeroed so it can be mapped to userspace
524  * without leaking data.
525  */
526 void *vmalloc_user(unsigned long size)
527 {
528 	struct vm_struct *area;
529 	void *ret;
530 
531 	ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, PAGE_KERNEL);
532 	if (ret) {
533 		write_lock(&vmlist_lock);
534 		area = __find_vm_area(ret);
535 		area->flags |= VM_USERMAP;
536 		write_unlock(&vmlist_lock);
537 	}
538 	return ret;
539 }
540 EXPORT_SYMBOL(vmalloc_user);
541 
542 /**
543  *	vmalloc_node  -  allocate memory on a specific node
544  *	@size:		allocation size
545  *	@node:		numa node
546  *
547  *	Allocate enough pages to cover @size from the page level
548  *	allocator and map them into contiguous kernel virtual space.
549  *
550  *	For tight control over page level allocator and protection flags
551  *	use __vmalloc() instead.
552  */
553 void *vmalloc_node(unsigned long size, int node)
554 {
555 	return __vmalloc_node(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL, node);
556 }
557 EXPORT_SYMBOL(vmalloc_node);
558 
559 #ifndef PAGE_KERNEL_EXEC
560 # define PAGE_KERNEL_EXEC PAGE_KERNEL
561 #endif
562 
563 /**
564  *	vmalloc_exec  -  allocate virtually contiguous, executable memory
565  *	@size:		allocation size
566  *
567  *	Kernel-internal function to allocate enough pages to cover @size
568  *	the page level allocator and map them into contiguous and
569  *	executable kernel virtual space.
570  *
571  *	For tight control over page level allocator and protection flags
572  *	use __vmalloc() instead.
573  */
574 
575 void *vmalloc_exec(unsigned long size)
576 {
577 	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
578 }
579 
580 #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32)
581 #define GFP_VMALLOC32 GFP_DMA32
582 #elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA)
583 #define GFP_VMALLOC32 GFP_DMA
584 #else
585 #define GFP_VMALLOC32 GFP_KERNEL
586 #endif
587 
588 /**
589  *	vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
590  *	@size:		allocation size
591  *
592  *	Allocate enough 32bit PA addressable pages to cover @size from the
593  *	page level allocator and map them into contiguous kernel virtual space.
594  */
595 void *vmalloc_32(unsigned long size)
596 {
597 	return __vmalloc(size, GFP_VMALLOC32, PAGE_KERNEL);
598 }
599 EXPORT_SYMBOL(vmalloc_32);
600 
601 /**
602  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
603  *	@size:		allocation size
604  *
605  * The resulting memory area is 32bit addressable and zeroed so it can be
606  * mapped to userspace without leaking data.
607  */
608 void *vmalloc_32_user(unsigned long size)
609 {
610 	struct vm_struct *area;
611 	void *ret;
612 
613 	ret = __vmalloc(size, GFP_VMALLOC32 | __GFP_ZERO, PAGE_KERNEL);
614 	if (ret) {
615 		write_lock(&vmlist_lock);
616 		area = __find_vm_area(ret);
617 		area->flags |= VM_USERMAP;
618 		write_unlock(&vmlist_lock);
619 	}
620 	return ret;
621 }
622 EXPORT_SYMBOL(vmalloc_32_user);
623 
624 long vread(char *buf, char *addr, unsigned long count)
625 {
626 	struct vm_struct *tmp;
627 	char *vaddr, *buf_start = buf;
628 	unsigned long n;
629 
630 	/* Don't allow overflow */
631 	if ((unsigned long) addr + count < count)
632 		count = -(unsigned long) addr;
633 
634 	read_lock(&vmlist_lock);
635 	for (tmp = vmlist; tmp; tmp = tmp->next) {
636 		vaddr = (char *) tmp->addr;
637 		if (addr >= vaddr + tmp->size - PAGE_SIZE)
638 			continue;
639 		while (addr < vaddr) {
640 			if (count == 0)
641 				goto finished;
642 			*buf = '\0';
643 			buf++;
644 			addr++;
645 			count--;
646 		}
647 		n = vaddr + tmp->size - PAGE_SIZE - addr;
648 		do {
649 			if (count == 0)
650 				goto finished;
651 			*buf = *addr;
652 			buf++;
653 			addr++;
654 			count--;
655 		} while (--n > 0);
656 	}
657 finished:
658 	read_unlock(&vmlist_lock);
659 	return buf - buf_start;
660 }
661 
662 long vwrite(char *buf, char *addr, unsigned long count)
663 {
664 	struct vm_struct *tmp;
665 	char *vaddr, *buf_start = buf;
666 	unsigned long n;
667 
668 	/* Don't allow overflow */
669 	if ((unsigned long) addr + count < count)
670 		count = -(unsigned long) addr;
671 
672 	read_lock(&vmlist_lock);
673 	for (tmp = vmlist; tmp; tmp = tmp->next) {
674 		vaddr = (char *) tmp->addr;
675 		if (addr >= vaddr + tmp->size - PAGE_SIZE)
676 			continue;
677 		while (addr < vaddr) {
678 			if (count == 0)
679 				goto finished;
680 			buf++;
681 			addr++;
682 			count--;
683 		}
684 		n = vaddr + tmp->size - PAGE_SIZE - addr;
685 		do {
686 			if (count == 0)
687 				goto finished;
688 			*addr = *buf;
689 			buf++;
690 			addr++;
691 			count--;
692 		} while (--n > 0);
693 	}
694 finished:
695 	read_unlock(&vmlist_lock);
696 	return buf - buf_start;
697 }
698 
699 /**
700  *	remap_vmalloc_range  -  map vmalloc pages to userspace
701  *	@vma:		vma to cover (map full range of vma)
702  *	@addr:		vmalloc memory
703  *	@pgoff:		number of pages into addr before first page to map
704  *	@returns:	0 for success, -Exxx on failure
705  *
706  *	This function checks that addr is a valid vmalloc'ed area, and
707  *	that it is big enough to cover the vma. Will return failure if
708  *	that criteria isn't met.
709  *
710  *	Similar to remap_pfn_range() (see mm/memory.c)
711  */
712 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
713 						unsigned long pgoff)
714 {
715 	struct vm_struct *area;
716 	unsigned long uaddr = vma->vm_start;
717 	unsigned long usize = vma->vm_end - vma->vm_start;
718 	int ret;
719 
720 	if ((PAGE_SIZE-1) & (unsigned long)addr)
721 		return -EINVAL;
722 
723 	read_lock(&vmlist_lock);
724 	area = __find_vm_area(addr);
725 	if (!area)
726 		goto out_einval_locked;
727 
728 	if (!(area->flags & VM_USERMAP))
729 		goto out_einval_locked;
730 
731 	if (usize + (pgoff << PAGE_SHIFT) > area->size - PAGE_SIZE)
732 		goto out_einval_locked;
733 	read_unlock(&vmlist_lock);
734 
735 	addr += pgoff << PAGE_SHIFT;
736 	do {
737 		struct page *page = vmalloc_to_page(addr);
738 		ret = vm_insert_page(vma, uaddr, page);
739 		if (ret)
740 			return ret;
741 
742 		uaddr += PAGE_SIZE;
743 		addr += PAGE_SIZE;
744 		usize -= PAGE_SIZE;
745 	} while (usize > 0);
746 
747 	/* Prevent "things" like memory migration? VM_flags need a cleanup... */
748 	vma->vm_flags |= VM_RESERVED;
749 
750 	return ret;
751 
752 out_einval_locked:
753 	read_unlock(&vmlist_lock);
754 	return -EINVAL;
755 }
756 EXPORT_SYMBOL(remap_vmalloc_range);
757 
758 /*
759  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
760  * have one.
761  */
762 void  __attribute__((weak)) vmalloc_sync_all(void)
763 {
764 }
765