Root/mm/nommu.c

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#include <linux/module.h>
17#include <linux/mm.h>
18#include <linux/mman.h>
19#include <linux/swap.h>
20#include <linux/file.h>
21#include <linux/highmem.h>
22#include <linux/pagemap.h>
23#include <linux/slab.h>
24#include <linux/vmalloc.h>
25#include <linux/tracehook.h>
26#include <linux/blkdev.h>
27#include <linux/backing-dev.h>
28#include <linux/mount.h>
29#include <linux/personality.h>
30#include <linux/security.h>
31#include <linux/syscalls.h>
32#include <linux/audit.h>
33
34#include <asm/uaccess.h>
35#include <asm/tlb.h>
36#include <asm/tlbflush.h>
37#include <asm/mmu_context.h>
38#include "internal.h"
39
40#if 0
41#define kenter(FMT, ...) \
42    printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
43#define kleave(FMT, ...) \
44    printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
45#define kdebug(FMT, ...) \
46    printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
47#else
48#define kenter(FMT, ...) \
49    no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
50#define kleave(FMT, ...) \
51    no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
52#define kdebug(FMT, ...) \
53    no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
54#endif
55
56void *high_memory;
57struct page *mem_map;
58unsigned long max_mapnr;
59unsigned long num_physpages;
60unsigned long highest_memmap_pfn;
61struct percpu_counter vm_committed_as;
62int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
63int sysctl_overcommit_ratio = 50; /* default is 50% */
64int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
65int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
66int heap_stack_gap = 0;
67
68atomic_long_t mmap_pages_allocated;
69
70EXPORT_SYMBOL(mem_map);
71EXPORT_SYMBOL(num_physpages);
72
73/* list of mapped, potentially shareable regions */
74static struct kmem_cache *vm_region_jar;
75struct rb_root nommu_region_tree = RB_ROOT;
76DECLARE_RWSEM(nommu_region_sem);
77
78const struct vm_operations_struct generic_file_vm_ops = {
79};
80
81/*
82 * Return the total memory allocated for this pointer, not
83 * just what the caller asked for.
84 *
85 * Doesn't have to be accurate, i.e. may have races.
86 */
87unsigned int kobjsize(const void *objp)
88{
89    struct page *page;
90
91    /*
92     * If the object we have should not have ksize performed on it,
93     * return size of 0
94     */
95    if (!objp || !virt_addr_valid(objp))
96        return 0;
97
98    page = virt_to_head_page(objp);
99
100    /*
101     * If the allocator sets PageSlab, we know the pointer came from
102     * kmalloc().
103     */
104    if (PageSlab(page))
105        return ksize(objp);
106
107    /*
108     * If it's not a compound page, see if we have a matching VMA
109     * region. This test is intentionally done in reverse order,
110     * so if there's no VMA, we still fall through and hand back
111     * PAGE_SIZE for 0-order pages.
112     */
113    if (!PageCompound(page)) {
114        struct vm_area_struct *vma;
115
116        vma = find_vma(current->mm, (unsigned long)objp);
117        if (vma)
118            return vma->vm_end - vma->vm_start;
119    }
120
121    /*
122     * The ksize() function is only guaranteed to work for pointers
123     * returned by kmalloc(). So handle arbitrary pointers here.
124     */
125    return PAGE_SIZE << compound_order(page);
126}
127
128int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
129             unsigned long start, int nr_pages, unsigned int foll_flags,
130             struct page **pages, struct vm_area_struct **vmas,
131             int *retry)
132{
133    struct vm_area_struct *vma;
134    unsigned long vm_flags;
135    int i;
136
137    /* calculate required read or write permissions.
138     * If FOLL_FORCE is set, we only require the "MAY" flags.
139     */
140    vm_flags = (foll_flags & FOLL_WRITE) ?
141            (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
142    vm_flags &= (foll_flags & FOLL_FORCE) ?
143            (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
144
145    for (i = 0; i < nr_pages; i++) {
146        vma = find_vma(mm, start);
147        if (!vma)
148            goto finish_or_fault;
149
150        /* protect what we can, including chardevs */
151        if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
152            !(vm_flags & vma->vm_flags))
153            goto finish_or_fault;
154
155        if (pages) {
156            pages[i] = virt_to_page(start);
157            if (pages[i])
158                page_cache_get(pages[i]);
159        }
160        if (vmas)
161            vmas[i] = vma;
162        start = (start + PAGE_SIZE) & PAGE_MASK;
163    }
164
165    return i;
166
167finish_or_fault:
168    return i ? : -EFAULT;
169}
170
171/*
172 * get a list of pages in an address range belonging to the specified process
173 * and indicate the VMA that covers each page
174 * - this is potentially dodgy as we may end incrementing the page count of a
175 * slab page or a secondary page from a compound page
176 * - don't permit access to VMAs that don't support it, such as I/O mappings
177 */
178int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
179    unsigned long start, int nr_pages, int write, int force,
180    struct page **pages, struct vm_area_struct **vmas)
181{
182    int flags = 0;
183
184    if (write)
185        flags |= FOLL_WRITE;
186    if (force)
187        flags |= FOLL_FORCE;
188
189    return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
190                NULL);
191}
192EXPORT_SYMBOL(get_user_pages);
193
194/**
195 * follow_pfn - look up PFN at a user virtual address
196 * @vma: memory mapping
197 * @address: user virtual address
198 * @pfn: location to store found PFN
199 *
200 * Only IO mappings and raw PFN mappings are allowed.
201 *
202 * Returns zero and the pfn at @pfn on success, -ve otherwise.
203 */
204int follow_pfn(struct vm_area_struct *vma, unsigned long address,
205    unsigned long *pfn)
206{
207    if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
208        return -EINVAL;
209
210    *pfn = address >> PAGE_SHIFT;
211    return 0;
212}
213EXPORT_SYMBOL(follow_pfn);
214
215DEFINE_RWLOCK(vmlist_lock);
216struct vm_struct *vmlist;
217
218void vfree(const void *addr)
219{
220    kfree(addr);
221}
222EXPORT_SYMBOL(vfree);
223
224void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
225{
226    /*
227     * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
228     * returns only a logical address.
229     */
230    return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
231}
232EXPORT_SYMBOL(__vmalloc);
233
234void *vmalloc_user(unsigned long size)
235{
236    void *ret;
237
238    ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
239            PAGE_KERNEL);
240    if (ret) {
241        struct vm_area_struct *vma;
242
243        down_write(&current->mm->mmap_sem);
244        vma = find_vma(current->mm, (unsigned long)ret);
245        if (vma)
246            vma->vm_flags |= VM_USERMAP;
247        up_write(&current->mm->mmap_sem);
248    }
249
250    return ret;
251}
252EXPORT_SYMBOL(vmalloc_user);
253
254struct page *vmalloc_to_page(const void *addr)
255{
256    return virt_to_page(addr);
257}
258EXPORT_SYMBOL(vmalloc_to_page);
259
260unsigned long vmalloc_to_pfn(const void *addr)
261{
262    return page_to_pfn(virt_to_page(addr));
263}
264EXPORT_SYMBOL(vmalloc_to_pfn);
265
266long vread(char *buf, char *addr, unsigned long count)
267{
268    memcpy(buf, addr, count);
269    return count;
270}
271
272long vwrite(char *buf, char *addr, unsigned long count)
273{
274    /* Don't allow overflow */
275    if ((unsigned long) addr + count < count)
276        count = -(unsigned long) addr;
277
278    memcpy(addr, buf, count);
279    return(count);
280}
281
282/*
283 * vmalloc - allocate virtually continguos memory
284 *
285 * @size: allocation size
286 *
287 * Allocate enough pages to cover @size from the page level
288 * allocator and map them into continguos kernel virtual space.
289 *
290 * For tight control over page level allocator and protection flags
291 * use __vmalloc() instead.
292 */
293void *vmalloc(unsigned long size)
294{
295       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
296}
297EXPORT_SYMBOL(vmalloc);
298
299/*
300 * vzalloc - allocate virtually continguos memory with zero fill
301 *
302 * @size: allocation size
303 *
304 * Allocate enough pages to cover @size from the page level
305 * allocator and map them into continguos kernel virtual space.
306 * The memory allocated is set to zero.
307 *
308 * For tight control over page level allocator and protection flags
309 * use __vmalloc() instead.
310 */
311void *vzalloc(unsigned long size)
312{
313    return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
314            PAGE_KERNEL);
315}
316EXPORT_SYMBOL(vzalloc);
317
318/**
319 * vmalloc_node - allocate memory on a specific node
320 * @size: allocation size
321 * @node: numa node
322 *
323 * Allocate enough pages to cover @size from the page level
324 * allocator and map them into contiguous kernel virtual space.
325 *
326 * For tight control over page level allocator and protection flags
327 * use __vmalloc() instead.
328 */
329void *vmalloc_node(unsigned long size, int node)
330{
331    return vmalloc(size);
332}
333EXPORT_SYMBOL(vmalloc_node);
334
335/**
336 * vzalloc_node - allocate memory on a specific node with zero fill
337 * @size: allocation size
338 * @node: numa node
339 *
340 * Allocate enough pages to cover @size from the page level
341 * allocator and map them into contiguous kernel virtual space.
342 * The memory allocated is set to zero.
343 *
344 * For tight control over page level allocator and protection flags
345 * use __vmalloc() instead.
346 */
347void *vzalloc_node(unsigned long size, int node)
348{
349    return vzalloc(size);
350}
351EXPORT_SYMBOL(vzalloc_node);
352
353#ifndef PAGE_KERNEL_EXEC
354# define PAGE_KERNEL_EXEC PAGE_KERNEL
355#endif
356
357/**
358 * vmalloc_exec - allocate virtually contiguous, executable memory
359 * @size: allocation size
360 *
361 * Kernel-internal function to allocate enough pages to cover @size
362 * the page level allocator and map them into contiguous and
363 * executable kernel virtual space.
364 *
365 * For tight control over page level allocator and protection flags
366 * use __vmalloc() instead.
367 */
368
369void *vmalloc_exec(unsigned long size)
370{
371    return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
372}
373
374/**
375 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
376 * @size: allocation size
377 *
378 * Allocate enough 32bit PA addressable pages to cover @size from the
379 * page level allocator and map them into continguos kernel virtual space.
380 */
381void *vmalloc_32(unsigned long size)
382{
383    return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
384}
385EXPORT_SYMBOL(vmalloc_32);
386
387/**
388 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
389 * @size: allocation size
390 *
391 * The resulting memory area is 32bit addressable and zeroed so it can be
392 * mapped to userspace without leaking data.
393 *
394 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
395 * remap_vmalloc_range() are permissible.
396 */
397void *vmalloc_32_user(unsigned long size)
398{
399    /*
400     * We'll have to sort out the ZONE_DMA bits for 64-bit,
401     * but for now this can simply use vmalloc_user() directly.
402     */
403    return vmalloc_user(size);
404}
405EXPORT_SYMBOL(vmalloc_32_user);
406
407void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
408{
409    BUG();
410    return NULL;
411}
412EXPORT_SYMBOL(vmap);
413
414void vunmap(const void *addr)
415{
416    BUG();
417}
418EXPORT_SYMBOL(vunmap);
419
420void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
421{
422    BUG();
423    return NULL;
424}
425EXPORT_SYMBOL(vm_map_ram);
426
427void vm_unmap_ram(const void *mem, unsigned int count)
428{
429    BUG();
430}
431EXPORT_SYMBOL(vm_unmap_ram);
432
433void vm_unmap_aliases(void)
434{
435}
436EXPORT_SYMBOL_GPL(vm_unmap_aliases);
437
438/*
439 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
440 * have one.
441 */
442void __attribute__((weak)) vmalloc_sync_all(void)
443{
444}
445
446/**
447 * alloc_vm_area - allocate a range of kernel address space
448 * @size: size of the area
449 *
450 * Returns: NULL on failure, vm_struct on success
451 *
452 * This function reserves a range of kernel address space, and
453 * allocates pagetables to map that range. No actual mappings
454 * are created. If the kernel address space is not shared
455 * between processes, it syncs the pagetable across all
456 * processes.
457 */
458struct vm_struct *alloc_vm_area(size_t size)
459{
460    BUG();
461    return NULL;
462}
463EXPORT_SYMBOL_GPL(alloc_vm_area);
464
465void free_vm_area(struct vm_struct *area)
466{
467    BUG();
468}
469EXPORT_SYMBOL_GPL(free_vm_area);
470
471int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
472           struct page *page)
473{
474    return -EINVAL;
475}
476EXPORT_SYMBOL(vm_insert_page);
477
478/*
479 * sys_brk() for the most part doesn't need the global kernel
480 * lock, except when an application is doing something nasty
481 * like trying to un-brk an area that has already been mapped
482 * to a regular file. in this case, the unmapping will need
483 * to invoke file system routines that need the global lock.
484 */
485SYSCALL_DEFINE1(brk, unsigned long, brk)
486{
487    struct mm_struct *mm = current->mm;
488
489    if (brk < mm->start_brk || brk > mm->context.end_brk)
490        return mm->brk;
491
492    if (mm->brk == brk)
493        return mm->brk;
494
495    /*
496     * Always allow shrinking brk
497     */
498    if (brk <= mm->brk) {
499        mm->brk = brk;
500        return brk;
501    }
502
503    /*
504     * Ok, looks good - let it rip.
505     */
506    flush_icache_range(mm->brk, brk);
507    return mm->brk = brk;
508}
509
510/*
511 * initialise the VMA and region record slabs
512 */
513void __init mmap_init(void)
514{
515    int ret;
516
517    ret = percpu_counter_init(&vm_committed_as, 0);
518    VM_BUG_ON(ret);
519    vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
520}
521
522/*
523 * validate the region tree
524 * - the caller must hold the region lock
525 */
526#ifdef CONFIG_DEBUG_NOMMU_REGIONS
527static noinline void validate_nommu_regions(void)
528{
529    struct vm_region *region, *last;
530    struct rb_node *p, *lastp;
531
532    lastp = rb_first(&nommu_region_tree);
533    if (!lastp)
534        return;
535
536    last = rb_entry(lastp, struct vm_region, vm_rb);
537    BUG_ON(unlikely(last->vm_end <= last->vm_start));
538    BUG_ON(unlikely(last->vm_top < last->vm_end));
539
540    while ((p = rb_next(lastp))) {
541        region = rb_entry(p, struct vm_region, vm_rb);
542        last = rb_entry(lastp, struct vm_region, vm_rb);
543
544        BUG_ON(unlikely(region->vm_end <= region->vm_start));
545        BUG_ON(unlikely(region->vm_top < region->vm_end));
546        BUG_ON(unlikely(region->vm_start < last->vm_top));
547
548        lastp = p;
549    }
550}
551#else
552static void validate_nommu_regions(void)
553{
554}
555#endif
556
557/*
558 * add a region into the global tree
559 */
560static void add_nommu_region(struct vm_region *region)
561{
562    struct vm_region *pregion;
563    struct rb_node **p, *parent;
564
565    validate_nommu_regions();
566
567    parent = NULL;
568    p = &nommu_region_tree.rb_node;
569    while (*p) {
570        parent = *p;
571        pregion = rb_entry(parent, struct vm_region, vm_rb);
572        if (region->vm_start < pregion->vm_start)
573            p = &(*p)->rb_left;
574        else if (region->vm_start > pregion->vm_start)
575            p = &(*p)->rb_right;
576        else if (pregion == region)
577            return;
578        else
579            BUG();
580    }
581
582    rb_link_node(&region->vm_rb, parent, p);
583    rb_insert_color(&region->vm_rb, &nommu_region_tree);
584
585    validate_nommu_regions();
586}
587
588/*
589 * delete a region from the global tree
590 */
591static void delete_nommu_region(struct vm_region *region)
592{
593    BUG_ON(!nommu_region_tree.rb_node);
594
595    validate_nommu_regions();
596    rb_erase(&region->vm_rb, &nommu_region_tree);
597    validate_nommu_regions();
598}
599
600/*
601 * free a contiguous series of pages
602 */
603static void free_page_series(unsigned long from, unsigned long to)
604{
605    for (; from < to; from += PAGE_SIZE) {
606        struct page *page = virt_to_page(from);
607
608        kdebug("- free %lx", from);
609        atomic_long_dec(&mmap_pages_allocated);
610        if (page_count(page) != 1)
611            kdebug("free page %p: refcount not one: %d",
612                   page, page_count(page));
613        put_page(page);
614    }
615}
616
617/*
618 * release a reference to a region
619 * - the caller must hold the region semaphore for writing, which this releases
620 * - the region may not have been added to the tree yet, in which case vm_top
621 * will equal vm_start
622 */
623static void __put_nommu_region(struct vm_region *region)
624    __releases(nommu_region_sem)
625{
626    kenter("%p{%d}", region, region->vm_usage);
627
628    BUG_ON(!nommu_region_tree.rb_node);
629
630    if (--region->vm_usage == 0) {
631        if (region->vm_top > region->vm_start)
632            delete_nommu_region(region);
633        up_write(&nommu_region_sem);
634
635        if (region->vm_file)
636            fput(region->vm_file);
637
638        /* IO memory and memory shared directly out of the pagecache
639         * from ramfs/tmpfs mustn't be released here */
640        if (region->vm_flags & VM_MAPPED_COPY) {
641            kdebug("free series");
642            free_page_series(region->vm_start, region->vm_top);
643        }
644        kmem_cache_free(vm_region_jar, region);
645    } else {
646        up_write(&nommu_region_sem);
647    }
648}
649
650/*
651 * release a reference to a region
652 */
653static void put_nommu_region(struct vm_region *region)
654{
655    down_write(&nommu_region_sem);
656    __put_nommu_region(region);
657}
658
659/*
660 * update protection on a vma
661 */
662static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
663{
664#ifdef CONFIG_MPU
665    struct mm_struct *mm = vma->vm_mm;
666    long start = vma->vm_start & PAGE_MASK;
667    while (start < vma->vm_end) {
668        protect_page(mm, start, flags);
669        start += PAGE_SIZE;
670    }
671    update_protections(mm);
672#endif
673}
674
675/*
676 * add a VMA into a process's mm_struct in the appropriate place in the list
677 * and tree and add to the address space's page tree also if not an anonymous
678 * page
679 * - should be called with mm->mmap_sem held writelocked
680 */
681static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
682{
683    struct vm_area_struct *pvma, *prev;
684    struct address_space *mapping;
685    struct rb_node **p, *parent, *rb_prev;
686
687    kenter(",%p", vma);
688
689    BUG_ON(!vma->vm_region);
690
691    mm->map_count++;
692    vma->vm_mm = mm;
693
694    protect_vma(vma, vma->vm_flags);
695
696    /* add the VMA to the mapping */
697    if (vma->vm_file) {
698        mapping = vma->vm_file->f_mapping;
699
700        flush_dcache_mmap_lock(mapping);
701        vma_prio_tree_insert(vma, &mapping->i_mmap);
702        flush_dcache_mmap_unlock(mapping);
703    }
704
705    /* add the VMA to the tree */
706    parent = rb_prev = NULL;
707    p = &mm->mm_rb.rb_node;
708    while (*p) {
709        parent = *p;
710        pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
711
712        /* sort by: start addr, end addr, VMA struct addr in that order
713         * (the latter is necessary as we may get identical VMAs) */
714        if (vma->vm_start < pvma->vm_start)
715            p = &(*p)->rb_left;
716        else if (vma->vm_start > pvma->vm_start) {
717            rb_prev = parent;
718            p = &(*p)->rb_right;
719        } else if (vma->vm_end < pvma->vm_end)
720            p = &(*p)->rb_left;
721        else if (vma->vm_end > pvma->vm_end) {
722            rb_prev = parent;
723            p = &(*p)->rb_right;
724        } else if (vma < pvma)
725            p = &(*p)->rb_left;
726        else if (vma > pvma) {
727            rb_prev = parent;
728            p = &(*p)->rb_right;
729        } else
730            BUG();
731    }
732
733    rb_link_node(&vma->vm_rb, parent, p);
734    rb_insert_color(&vma->vm_rb, &mm->mm_rb);
735
736    /* add VMA to the VMA list also */
737    prev = NULL;
738    if (rb_prev)
739        prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
740
741    __vma_link_list(mm, vma, prev, parent);
742}
743
744/*
745 * delete a VMA from its owning mm_struct and address space
746 */
747static void delete_vma_from_mm(struct vm_area_struct *vma)
748{
749    struct address_space *mapping;
750    struct mm_struct *mm = vma->vm_mm;
751
752    kenter("%p", vma);
753
754    protect_vma(vma, 0);
755
756    mm->map_count--;
757    if (mm->mmap_cache == vma)
758        mm->mmap_cache = NULL;
759
760    /* remove the VMA from the mapping */
761    if (vma->vm_file) {
762        mapping = vma->vm_file->f_mapping;
763
764        flush_dcache_mmap_lock(mapping);
765        vma_prio_tree_remove(vma, &mapping->i_mmap);
766        flush_dcache_mmap_unlock(mapping);
767    }
768
769    /* remove from the MM's tree and list */
770    rb_erase(&vma->vm_rb, &mm->mm_rb);
771
772    if (vma->vm_prev)
773        vma->vm_prev->vm_next = vma->vm_next;
774    else
775        mm->mmap = vma->vm_next;
776
777    if (vma->vm_next)
778        vma->vm_next->vm_prev = vma->vm_prev;
779
780    vma->vm_mm = NULL;
781}
782
783/*
784 * destroy a VMA record
785 */
786static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
787{
788    kenter("%p", vma);
789    if (vma->vm_ops && vma->vm_ops->close)
790        vma->vm_ops->close(vma);
791    if (vma->vm_file) {
792        fput(vma->vm_file);
793        if (vma->vm_flags & VM_EXECUTABLE)
794            removed_exe_file_vma(mm);
795    }
796    put_nommu_region(vma->vm_region);
797    kmem_cache_free(vm_area_cachep, vma);
798}
799
800/*
801 * look up the first VMA in which addr resides, NULL if none
802 * - should be called with mm->mmap_sem at least held readlocked
803 */
804struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
805{
806    struct vm_area_struct *vma;
807
808    /* check the cache first */
809    vma = mm->mmap_cache;
810    if (vma && vma->vm_start <= addr && vma->vm_end > addr)
811        return vma;
812
813    /* trawl the list (there may be multiple mappings in which addr
814     * resides) */
815    for (vma = mm->mmap; vma; vma = vma->vm_next) {
816        if (vma->vm_start > addr)
817            return NULL;
818        if (vma->vm_end > addr) {
819            mm->mmap_cache = vma;
820            return vma;
821        }
822    }
823
824    return NULL;
825}
826EXPORT_SYMBOL(find_vma);
827
828/*
829 * find a VMA
830 * - we don't extend stack VMAs under NOMMU conditions
831 */
832struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
833{
834    return find_vma(mm, addr);
835}
836
837/*
838 * expand a stack to a given address
839 * - not supported under NOMMU conditions
840 */
841int expand_stack(struct vm_area_struct *vma, unsigned long address)
842{
843    return -ENOMEM;
844}
845
846/*
847 * look up the first VMA exactly that exactly matches addr
848 * - should be called with mm->mmap_sem at least held readlocked
849 */
850static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
851                         unsigned long addr,
852                         unsigned long len)
853{
854    struct vm_area_struct *vma;
855    unsigned long end = addr + len;
856
857    /* check the cache first */
858    vma = mm->mmap_cache;
859    if (vma && vma->vm_start == addr && vma->vm_end == end)
860        return vma;
861
862    /* trawl the list (there may be multiple mappings in which addr
863     * resides) */
864    for (vma = mm->mmap; vma; vma = vma->vm_next) {
865        if (vma->vm_start < addr)
866            continue;
867        if (vma->vm_start > addr)
868            return NULL;
869        if (vma->vm_end == end) {
870            mm->mmap_cache = vma;
871            return vma;
872        }
873    }
874
875    return NULL;
876}
877
878/*
879 * determine whether a mapping should be permitted and, if so, what sort of
880 * mapping we're capable of supporting
881 */
882static int validate_mmap_request(struct file *file,
883                 unsigned long addr,
884                 unsigned long len,
885                 unsigned long prot,
886                 unsigned long flags,
887                 unsigned long pgoff,
888                 unsigned long *_capabilities)
889{
890    unsigned long capabilities, rlen;
891    unsigned long reqprot = prot;
892    int ret;
893
894    /* do the simple checks first */
895    if (flags & MAP_FIXED) {
896        printk(KERN_DEBUG
897               "%d: Can't do fixed-address/overlay mmap of RAM\n",
898               current->pid);
899        return -EINVAL;
900    }
901
902    if ((flags & MAP_TYPE) != MAP_PRIVATE &&
903        (flags & MAP_TYPE) != MAP_SHARED)
904        return -EINVAL;
905
906    if (!len)
907        return -EINVAL;
908
909    /* Careful about overflows.. */
910    rlen = PAGE_ALIGN(len);
911    if (!rlen || rlen > TASK_SIZE)
912        return -ENOMEM;
913
914    /* offset overflow? */
915    if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
916        return -EOVERFLOW;
917
918    if (file) {
919        /* validate file mapping requests */
920        struct address_space *mapping;
921
922        /* files must support mmap */
923        if (!file->f_op || !file->f_op->mmap)
924            return -ENODEV;
925
926        /* work out if what we've got could possibly be shared
927         * - we support chardevs that provide their own "memory"
928         * - we support files/blockdevs that are memory backed
929         */
930        mapping = file->f_mapping;
931        if (!mapping)
932            mapping = file->f_path.dentry->d_inode->i_mapping;
933
934        capabilities = 0;
935        if (mapping && mapping->backing_dev_info)
936            capabilities = mapping->backing_dev_info->capabilities;
937
938        if (!capabilities) {
939            /* no explicit capabilities set, so assume some
940             * defaults */
941            switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
942            case S_IFREG:
943            case S_IFBLK:
944                capabilities = BDI_CAP_MAP_COPY;
945                break;
946
947            case S_IFCHR:
948                capabilities =
949                    BDI_CAP_MAP_DIRECT |
950                    BDI_CAP_READ_MAP |
951                    BDI_CAP_WRITE_MAP;
952                break;
953
954            default:
955                return -EINVAL;
956            }
957        }
958
959        /* eliminate any capabilities that we can't support on this
960         * device */
961        if (!file->f_op->get_unmapped_area)
962            capabilities &= ~BDI_CAP_MAP_DIRECT;
963        if (!file->f_op->read)
964            capabilities &= ~BDI_CAP_MAP_COPY;
965
966        /* The file shall have been opened with read permission. */
967        if (!(file->f_mode & FMODE_READ))
968            return -EACCES;
969
970        if (flags & MAP_SHARED) {
971            /* do checks for writing, appending and locking */
972            if ((prot & PROT_WRITE) &&
973                !(file->f_mode & FMODE_WRITE))
974                return -EACCES;
975
976            if (IS_APPEND(file->f_path.dentry->d_inode) &&
977                (file->f_mode & FMODE_WRITE))
978                return -EACCES;
979
980            if (locks_verify_locked(file->f_path.dentry->d_inode))
981                return -EAGAIN;
982
983            if (!(capabilities & BDI_CAP_MAP_DIRECT))
984                return -ENODEV;
985
986            /* we mustn't privatise shared mappings */
987            capabilities &= ~BDI_CAP_MAP_COPY;
988        }
989        else {
990            /* we're going to read the file into private memory we
991             * allocate */
992            if (!(capabilities & BDI_CAP_MAP_COPY))
993                return -ENODEV;
994
995            /* we don't permit a private writable mapping to be
996             * shared with the backing device */
997            if (prot & PROT_WRITE)
998                capabilities &= ~BDI_CAP_MAP_DIRECT;
999        }
1000
1001        if (capabilities & BDI_CAP_MAP_DIRECT) {
1002            if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
1003                ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1004                ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
1005                ) {
1006                capabilities &= ~BDI_CAP_MAP_DIRECT;
1007                if (flags & MAP_SHARED) {
1008                    printk(KERN_WARNING
1009                           "MAP_SHARED not completely supported on !MMU\n");
1010                    return -EINVAL;
1011                }
1012            }
1013        }
1014
1015        /* handle executable mappings and implied executable
1016         * mappings */
1017        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1018            if (prot & PROT_EXEC)
1019                return -EPERM;
1020        }
1021        else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1022            /* handle implication of PROT_EXEC by PROT_READ */
1023            if (current->personality & READ_IMPLIES_EXEC) {
1024                if (capabilities & BDI_CAP_EXEC_MAP)
1025                    prot |= PROT_EXEC;
1026            }
1027        }
1028        else if ((prot & PROT_READ) &&
1029             (prot & PROT_EXEC) &&
1030             !(capabilities & BDI_CAP_EXEC_MAP)
1031             ) {
1032            /* backing file is not executable, try to copy */
1033            capabilities &= ~BDI_CAP_MAP_DIRECT;
1034        }
1035    }
1036    else {
1037        /* anonymous mappings are always memory backed and can be
1038         * privately mapped
1039         */
1040        capabilities = BDI_CAP_MAP_COPY;
1041
1042        /* handle PROT_EXEC implication by PROT_READ */
1043        if ((prot & PROT_READ) &&
1044            (current->personality & READ_IMPLIES_EXEC))
1045            prot |= PROT_EXEC;
1046    }
1047
1048    /* allow the security API to have its say */
1049    ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
1050    if (ret < 0)
1051        return ret;
1052
1053    /* looks okay */
1054    *_capabilities = capabilities;
1055    return 0;
1056}
1057
1058/*
1059 * we've determined that we can make the mapping, now translate what we
1060 * now know into VMA flags
1061 */
1062static unsigned long determine_vm_flags(struct file *file,
1063                    unsigned long prot,
1064                    unsigned long flags,
1065                    unsigned long capabilities)
1066{
1067    unsigned long vm_flags;
1068
1069    vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1070    /* vm_flags |= mm->def_flags; */
1071
1072    if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1073        /* attempt to share read-only copies of mapped file chunks */
1074        vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1075        if (file && !(prot & PROT_WRITE))
1076            vm_flags |= VM_MAYSHARE;
1077    } else {
1078        /* overlay a shareable mapping on the backing device or inode
1079         * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1080         * romfs/cramfs */
1081        vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1082        if (flags & MAP_SHARED)
1083            vm_flags |= VM_SHARED;
1084    }
1085
1086    /* refuse to let anyone share private mappings with this process if
1087     * it's being traced - otherwise breakpoints set in it may interfere
1088     * with another untraced process
1089     */
1090    if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
1091        vm_flags &= ~VM_MAYSHARE;
1092
1093    return vm_flags;
1094}
1095
1096/*
1097 * set up a shared mapping on a file (the driver or filesystem provides and
1098 * pins the storage)
1099 */
1100static int do_mmap_shared_file(struct vm_area_struct *vma)
1101{
1102    int ret;
1103
1104    ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1105    if (ret == 0) {
1106        vma->vm_region->vm_top = vma->vm_region->vm_end;
1107        return 0;
1108    }
1109    if (ret != -ENOSYS)
1110        return ret;
1111
1112    /* getting -ENOSYS indicates that direct mmap isn't possible (as
1113     * opposed to tried but failed) so we can only give a suitable error as
1114     * it's not possible to make a private copy if MAP_SHARED was given */
1115    return -ENODEV;
1116}
1117
1118/*
1119 * set up a private mapping or an anonymous shared mapping
1120 */
1121static int do_mmap_private(struct vm_area_struct *vma,
1122               struct vm_region *region,
1123               unsigned long len,
1124               unsigned long capabilities)
1125{
1126    struct page *pages;
1127    unsigned long total, point, n;
1128    void *base;
1129    int ret, order;
1130
1131    /* invoke the file's mapping function so that it can keep track of
1132     * shared mappings on devices or memory
1133     * - VM_MAYSHARE will be set if it may attempt to share
1134     */
1135    if (capabilities & BDI_CAP_MAP_DIRECT) {
1136        ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1137        if (ret == 0) {
1138            /* shouldn't return success if we're not sharing */
1139            BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1140            vma->vm_region->vm_top = vma->vm_region->vm_end;
1141            return 0;
1142        }
1143        if (ret != -ENOSYS)
1144            return ret;
1145
1146        /* getting an ENOSYS error indicates that direct mmap isn't
1147         * possible (as opposed to tried but failed) so we'll try to
1148         * make a private copy of the data and map that instead */
1149    }
1150
1151
1152    /* allocate some memory to hold the mapping
1153     * - note that this may not return a page-aligned address if the object
1154     * we're allocating is smaller than a page
1155     */
1156    order = get_order(len);
1157    kdebug("alloc order %d for %lx", order, len);
1158
1159    pages = alloc_pages(GFP_KERNEL, order);
1160    if (!pages)
1161        goto enomem;
1162
1163    total = 1 << order;
1164    atomic_long_add(total, &mmap_pages_allocated);
1165
1166    point = len >> PAGE_SHIFT;
1167
1168    /* we allocated a power-of-2 sized page set, so we may want to trim off
1169     * the excess */
1170    if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1171        while (total > point) {
1172            order = ilog2(total - point);
1173            n = 1 << order;
1174            kdebug("shave %lu/%lu @%lu", n, total - point, total);
1175            atomic_long_sub(n, &mmap_pages_allocated);
1176            total -= n;
1177            set_page_refcounted(pages + total);
1178            __free_pages(pages + total, order);
1179        }
1180    }
1181
1182    for (point = 1; point < total; point++)
1183        set_page_refcounted(&pages[point]);
1184
1185    base = page_address(pages);
1186    region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1187    region->vm_start = (unsigned long) base;
1188    region->vm_end = region->vm_start + len;
1189    region->vm_top = region->vm_start + (total << PAGE_SHIFT);
1190
1191    vma->vm_start = region->vm_start;
1192    vma->vm_end = region->vm_start + len;
1193
1194    if (vma->vm_file) {
1195        /* read the contents of a file into the copy */
1196        mm_segment_t old_fs;
1197        loff_t fpos;
1198
1199        fpos = vma->vm_pgoff;
1200        fpos <<= PAGE_SHIFT;
1201
1202        old_fs = get_fs();
1203        set_fs(KERNEL_DS);
1204        ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1205        set_fs(old_fs);
1206
1207        if (ret < 0)
1208            goto error_free;
1209
1210        /* clear the last little bit */
1211        if (ret < len)
1212            memset(base + ret, 0, len - ret);
1213
1214    }
1215
1216    return 0;
1217
1218error_free:
1219    free_page_series(region->vm_start, region->vm_top);
1220    region->vm_start = vma->vm_start = 0;
1221    region->vm_end = vma->vm_end = 0;
1222    region->vm_top = 0;
1223    return ret;
1224
1225enomem:
1226    printk("Allocation of length %lu from process %d (%s) failed\n",
1227           len, current->pid, current->comm);
1228    show_free_areas(0);
1229    return -ENOMEM;
1230}
1231
1232/*
1233 * handle mapping creation for uClinux
1234 */
1235unsigned long do_mmap_pgoff(struct file *file,
1236                unsigned long addr,
1237                unsigned long len,
1238                unsigned long prot,
1239                unsigned long flags,
1240                unsigned long pgoff)
1241{
1242    struct vm_area_struct *vma;
1243    struct vm_region *region;
1244    struct rb_node *rb;
1245    unsigned long capabilities, vm_flags, result;
1246    int ret;
1247
1248    kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1249
1250    /* decide whether we should attempt the mapping, and if so what sort of
1251     * mapping */
1252    ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1253                    &capabilities);
1254    if (ret < 0) {
1255        kleave(" = %d [val]", ret);
1256        return ret;
1257    }
1258
1259    /* we ignore the address hint */
1260    addr = 0;
1261    len = PAGE_ALIGN(len);
1262
1263    /* we've determined that we can make the mapping, now translate what we
1264     * now know into VMA flags */
1265    vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1266
1267    /* we're going to need to record the mapping */
1268    region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1269    if (!region)
1270        goto error_getting_region;
1271
1272    vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1273    if (!vma)
1274        goto error_getting_vma;
1275
1276    region->vm_usage = 1;
1277    region->vm_flags = vm_flags;
1278    region->vm_pgoff = pgoff;
1279
1280    INIT_LIST_HEAD(&vma->anon_vma_chain);
1281    vma->vm_flags = vm_flags;
1282    vma->vm_pgoff = pgoff;
1283
1284    if (file) {
1285        region->vm_file = file;
1286        get_file(file);
1287        vma->vm_file = file;
1288        get_file(file);
1289        if (vm_flags & VM_EXECUTABLE) {
1290            added_exe_file_vma(current->mm);
1291            vma->vm_mm = current->mm;
1292        }
1293    }
1294
1295    down_write(&nommu_region_sem);
1296
1297    /* if we want to share, we need to check for regions created by other
1298     * mmap() calls that overlap with our proposed mapping
1299     * - we can only share with a superset match on most regular files
1300     * - shared mappings on character devices and memory backed files are
1301     * permitted to overlap inexactly as far as we are concerned for in
1302     * these cases, sharing is handled in the driver or filesystem rather
1303     * than here
1304     */
1305    if (vm_flags & VM_MAYSHARE) {
1306        struct vm_region *pregion;
1307        unsigned long pglen, rpglen, pgend, rpgend, start;
1308
1309        pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1310        pgend = pgoff + pglen;
1311
1312        for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1313            pregion = rb_entry(rb, struct vm_region, vm_rb);
1314
1315            if (!(pregion->vm_flags & VM_MAYSHARE))
1316                continue;
1317
1318            /* search for overlapping mappings on the same file */
1319            if (pregion->vm_file->f_path.dentry->d_inode !=
1320                file->f_path.dentry->d_inode)
1321                continue;
1322
1323            if (pregion->vm_pgoff >= pgend)
1324                continue;
1325
1326            rpglen = pregion->vm_end - pregion->vm_start;
1327            rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1328            rpgend = pregion->vm_pgoff + rpglen;
1329            if (pgoff >= rpgend)
1330                continue;
1331
1332            /* handle inexactly overlapping matches between
1333             * mappings */
1334            if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1335                !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1336                /* new mapping is not a subset of the region */
1337                if (!(capabilities & BDI_CAP_MAP_DIRECT))
1338                    goto sharing_violation;
1339                continue;
1340            }
1341
1342            /* we've found a region we can share */
1343            pregion->vm_usage++;
1344            vma->vm_region = pregion;
1345            start = pregion->vm_start;
1346            start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1347            vma->vm_start = start;
1348            vma->vm_end = start + len;
1349
1350            if (pregion->vm_flags & VM_MAPPED_COPY) {
1351                kdebug("share copy");
1352                vma->vm_flags |= VM_MAPPED_COPY;
1353            } else {
1354                kdebug("share mmap");
1355                ret = do_mmap_shared_file(vma);
1356                if (ret < 0) {
1357                    vma->vm_region = NULL;
1358                    vma->vm_start = 0;
1359                    vma->vm_end = 0;
1360                    pregion->vm_usage--;
1361                    pregion = NULL;
1362                    goto error_just_free;
1363                }
1364            }
1365            fput(region->vm_file);
1366            kmem_cache_free(vm_region_jar, region);
1367            region = pregion;
1368            result = start;
1369            goto share;
1370        }
1371
1372        /* obtain the address at which to make a shared mapping
1373         * - this is the hook for quasi-memory character devices to
1374         * tell us the location of a shared mapping
1375         */
1376        if (capabilities & BDI_CAP_MAP_DIRECT) {
1377            addr = file->f_op->get_unmapped_area(file, addr, len,
1378                                 pgoff, flags);
1379            if (IS_ERR_VALUE(addr)) {
1380                ret = addr;
1381                if (ret != -ENOSYS)
1382                    goto error_just_free;
1383
1384                /* the driver refused to tell us where to site
1385                 * the mapping so we'll have to attempt to copy
1386                 * it */
1387                ret = -ENODEV;
1388                if (!(capabilities & BDI_CAP_MAP_COPY))
1389                    goto error_just_free;
1390
1391                capabilities &= ~BDI_CAP_MAP_DIRECT;
1392            } else {
1393                vma->vm_start = region->vm_start = addr;
1394                vma->vm_end = region->vm_end = addr + len;
1395            }
1396        }
1397    }
1398
1399    vma->vm_region = region;
1400
1401    /* set up the mapping
1402     * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1403     */
1404    if (file && vma->vm_flags & VM_SHARED)
1405        ret = do_mmap_shared_file(vma);
1406    else
1407        ret = do_mmap_private(vma, region, len, capabilities);
1408    if (ret < 0)
1409        goto error_just_free;
1410    add_nommu_region(region);
1411
1412    /* clear anonymous mappings that don't ask for uninitialized data */
1413    if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1414        memset((void *)region->vm_start, 0,
1415               region->vm_end - region->vm_start);
1416
1417    /* okay... we have a mapping; now we have to register it */
1418    result = vma->vm_start;
1419
1420    current->mm->total_vm += len >> PAGE_SHIFT;
1421
1422share:
1423    add_vma_to_mm(current->mm, vma);
1424
1425    /* we flush the region from the icache only when the first executable
1426     * mapping of it is made */
1427    if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1428        flush_icache_range(region->vm_start, region->vm_end);
1429        region->vm_icache_flushed = true;
1430    }
1431
1432    up_write(&nommu_region_sem);
1433
1434    kleave(" = %lx", result);
1435    return result;
1436
1437error_just_free:
1438    up_write(&nommu_region_sem);
1439error:
1440    if (region->vm_file)
1441        fput(region->vm_file);
1442    kmem_cache_free(vm_region_jar, region);
1443    if (vma->vm_file)
1444        fput(vma->vm_file);
1445    if (vma->vm_flags & VM_EXECUTABLE)
1446        removed_exe_file_vma(vma->vm_mm);
1447    kmem_cache_free(vm_area_cachep, vma);
1448    kleave(" = %d", ret);
1449    return ret;
1450
1451sharing_violation:
1452    up_write(&nommu_region_sem);
1453    printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1454    ret = -EINVAL;
1455    goto error;
1456
1457error_getting_vma:
1458    kmem_cache_free(vm_region_jar, region);
1459    printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1460           " from process %d failed\n",
1461           len, current->pid);
1462    show_free_areas(0);
1463    return -ENOMEM;
1464
1465error_getting_region:
1466    printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1467           " from process %d failed\n",
1468           len, current->pid);
1469    show_free_areas(0);
1470    return -ENOMEM;
1471}
1472EXPORT_SYMBOL(do_mmap_pgoff);
1473
1474SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1475        unsigned long, prot, unsigned long, flags,
1476        unsigned long, fd, unsigned long, pgoff)
1477{
1478    struct file *file = NULL;
1479    unsigned long retval = -EBADF;
1480
1481    audit_mmap_fd(fd, flags);
1482    if (!(flags & MAP_ANONYMOUS)) {
1483        file = fget(fd);
1484        if (!file)
1485            goto out;
1486    }
1487
1488    flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1489
1490    down_write(&current->mm->mmap_sem);
1491    retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1492    up_write(&current->mm->mmap_sem);
1493
1494    if (file)
1495        fput(file);
1496out:
1497    return retval;
1498}
1499
1500#ifdef __ARCH_WANT_SYS_OLD_MMAP
1501struct mmap_arg_struct {
1502    unsigned long addr;
1503    unsigned long len;
1504    unsigned long prot;
1505    unsigned long flags;
1506    unsigned long fd;
1507    unsigned long offset;
1508};
1509
1510SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1511{
1512    struct mmap_arg_struct a;
1513
1514    if (copy_from_user(&a, arg, sizeof(a)))
1515        return -EFAULT;
1516    if (a.offset & ~PAGE_MASK)
1517        return -EINVAL;
1518
1519    return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1520                  a.offset >> PAGE_SHIFT);
1521}
1522#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1523
1524/*
1525 * split a vma into two pieces at address 'addr', a new vma is allocated either
1526 * for the first part or the tail.
1527 */
1528int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1529          unsigned long addr, int new_below)
1530{
1531    struct vm_area_struct *new;
1532    struct vm_region *region;
1533    unsigned long npages;
1534
1535    kenter("");
1536
1537    /* we're only permitted to split anonymous regions (these should have
1538     * only a single usage on the region) */
1539    if (vma->vm_file)
1540        return -ENOMEM;
1541
1542    if (mm->map_count >= sysctl_max_map_count)
1543        return -ENOMEM;
1544
1545    region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1546    if (!region)
1547        return -ENOMEM;
1548
1549    new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1550    if (!new) {
1551        kmem_cache_free(vm_region_jar, region);
1552        return -ENOMEM;
1553    }
1554
1555    /* most fields are the same, copy all, and then fixup */
1556    *new = *vma;
1557    *region = *vma->vm_region;
1558    new->vm_region = region;
1559
1560    npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1561
1562    if (new_below) {
1563        region->vm_top = region->vm_end = new->vm_end = addr;
1564    } else {
1565        region->vm_start = new->vm_start = addr;
1566        region->vm_pgoff = new->vm_pgoff += npages;
1567    }
1568
1569    if (new->vm_ops && new->vm_ops->open)
1570        new->vm_ops->open(new);
1571
1572    delete_vma_from_mm(vma);
1573    down_write(&nommu_region_sem);
1574    delete_nommu_region(vma->vm_region);
1575    if (new_below) {
1576        vma->vm_region->vm_start = vma->vm_start = addr;
1577        vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1578    } else {
1579        vma->vm_region->vm_end = vma->vm_end = addr;
1580        vma->vm_region->vm_top = addr;
1581    }
1582    add_nommu_region(vma->vm_region);
1583    add_nommu_region(new->vm_region);
1584    up_write(&nommu_region_sem);
1585    add_vma_to_mm(mm, vma);
1586    add_vma_to_mm(mm, new);
1587    return 0;
1588}
1589
1590/*
1591 * shrink a VMA by removing the specified chunk from either the beginning or
1592 * the end
1593 */
1594static int shrink_vma(struct mm_struct *mm,
1595              struct vm_area_struct *vma,
1596              unsigned long from, unsigned long to)
1597{
1598    struct vm_region *region;
1599
1600    kenter("");
1601
1602    /* adjust the VMA's pointers, which may reposition it in the MM's tree
1603     * and list */
1604    delete_vma_from_mm(vma);
1605    if (from > vma->vm_start)
1606        vma->vm_end = from;
1607    else
1608        vma->vm_start = to;
1609    add_vma_to_mm(mm, vma);
1610
1611    /* cut the backing region down to size */
1612    region = vma->vm_region;
1613    BUG_ON(region->vm_usage != 1);
1614
1615    down_write(&nommu_region_sem);
1616    delete_nommu_region(region);
1617    if (from > region->vm_start) {
1618        to = region->vm_top;
1619        region->vm_top = region->vm_end = from;
1620    } else {
1621        region->vm_start = to;
1622    }
1623    add_nommu_region(region);
1624    up_write(&nommu_region_sem);
1625
1626    free_page_series(from, to);
1627    return 0;
1628}
1629
1630/*
1631 * release a mapping
1632 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1633 * VMA, though it need not cover the whole VMA
1634 */
1635int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1636{
1637    struct vm_area_struct *vma;
1638    unsigned long end;
1639    int ret;
1640
1641    kenter(",%lx,%zx", start, len);
1642
1643    len = PAGE_ALIGN(len);
1644    if (len == 0)
1645        return -EINVAL;
1646
1647    end = start + len;
1648
1649    /* find the first potentially overlapping VMA */
1650    vma = find_vma(mm, start);
1651    if (!vma) {
1652        static int limit = 0;
1653        if (limit < 5) {
1654            printk(KERN_WARNING
1655                   "munmap of memory not mmapped by process %d"
1656                   " (%s): 0x%lx-0x%lx\n",
1657                   current->pid, current->comm,
1658                   start, start + len - 1);
1659            limit++;
1660        }
1661        return -EINVAL;
1662    }
1663
1664    /* we're allowed to split an anonymous VMA but not a file-backed one */
1665    if (vma->vm_file) {
1666        do {
1667            if (start > vma->vm_start) {
1668                kleave(" = -EINVAL [miss]");
1669                return -EINVAL;
1670            }
1671            if (end == vma->vm_end)
1672                goto erase_whole_vma;
1673            vma = vma->vm_next;
1674        } while (vma);
1675        kleave(" = -EINVAL [split file]");
1676        return -EINVAL;
1677    } else {
1678        /* the chunk must be a subset of the VMA found */
1679        if (start == vma->vm_start && end == vma->vm_end)
1680            goto erase_whole_vma;
1681        if (start < vma->vm_start || end > vma->vm_end) {
1682            kleave(" = -EINVAL [superset]");
1683            return -EINVAL;
1684        }
1685        if (start & ~PAGE_MASK) {
1686            kleave(" = -EINVAL [unaligned start]");
1687            return -EINVAL;
1688        }
1689        if (end != vma->vm_end && end & ~PAGE_MASK) {
1690            kleave(" = -EINVAL [unaligned split]");
1691            return -EINVAL;
1692        }
1693        if (start != vma->vm_start && end != vma->vm_end) {
1694            ret = split_vma(mm, vma, start, 1);
1695            if (ret < 0) {
1696                kleave(" = %d [split]", ret);
1697                return ret;
1698            }
1699        }
1700        return shrink_vma(mm, vma, start, end);
1701    }
1702
1703erase_whole_vma:
1704    delete_vma_from_mm(vma);
1705    delete_vma(mm, vma);
1706    kleave(" = 0");
1707    return 0;
1708}
1709EXPORT_SYMBOL(do_munmap);
1710
1711SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1712{
1713    int ret;
1714    struct mm_struct *mm = current->mm;
1715
1716    down_write(&mm->mmap_sem);
1717    ret = do_munmap(mm, addr, len);
1718    up_write(&mm->mmap_sem);
1719    return ret;
1720}
1721
1722/*
1723 * release all the mappings made in a process's VM space
1724 */
1725void exit_mmap(struct mm_struct *mm)
1726{
1727    struct vm_area_struct *vma;
1728
1729    if (!mm)
1730        return;
1731
1732    kenter("");
1733
1734    mm->total_vm = 0;
1735
1736    while ((vma = mm->mmap)) {
1737        mm->mmap = vma->vm_next;
1738        delete_vma_from_mm(vma);
1739        delete_vma(mm, vma);
1740        cond_resched();
1741    }
1742
1743    kleave("");
1744}
1745
1746unsigned long do_brk(unsigned long addr, unsigned long len)
1747{
1748    return -ENOMEM;
1749}
1750
1751/*
1752 * expand (or shrink) an existing mapping, potentially moving it at the same
1753 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1754 *
1755 * under NOMMU conditions, we only permit changing a mapping's size, and only
1756 * as long as it stays within the region allocated by do_mmap_private() and the
1757 * block is not shareable
1758 *
1759 * MREMAP_FIXED is not supported under NOMMU conditions
1760 */
1761unsigned long do_mremap(unsigned long addr,
1762            unsigned long old_len, unsigned long new_len,
1763            unsigned long flags, unsigned long new_addr)
1764{
1765    struct vm_area_struct *vma;
1766
1767    /* insanity checks first */
1768    old_len = PAGE_ALIGN(old_len);
1769    new_len = PAGE_ALIGN(new_len);
1770    if (old_len == 0 || new_len == 0)
1771        return (unsigned long) -EINVAL;
1772
1773    if (addr & ~PAGE_MASK)
1774        return -EINVAL;
1775
1776    if (flags & MREMAP_FIXED && new_addr != addr)
1777        return (unsigned long) -EINVAL;
1778
1779    vma = find_vma_exact(current->mm, addr, old_len);
1780    if (!vma)
1781        return (unsigned long) -EINVAL;
1782
1783    if (vma->vm_end != vma->vm_start + old_len)
1784        return (unsigned long) -EFAULT;
1785
1786    if (vma->vm_flags & VM_MAYSHARE)
1787        return (unsigned long) -EPERM;
1788
1789    if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1790        return (unsigned long) -ENOMEM;
1791
1792    /* all checks complete - do it */
1793    vma->vm_end = vma->vm_start + new_len;
1794    return vma->vm_start;
1795}
1796EXPORT_SYMBOL(do_mremap);
1797
1798SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1799        unsigned long, new_len, unsigned long, flags,
1800        unsigned long, new_addr)
1801{
1802    unsigned long ret;
1803
1804    down_write(&current->mm->mmap_sem);
1805    ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1806    up_write(&current->mm->mmap_sem);
1807    return ret;
1808}
1809
1810struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1811            unsigned int foll_flags)
1812{
1813    return NULL;
1814}
1815
1816int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1817        unsigned long pfn, unsigned long size, pgprot_t prot)
1818{
1819    if (addr != (pfn << PAGE_SHIFT))
1820        return -EINVAL;
1821
1822    vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1823    return 0;
1824}
1825EXPORT_SYMBOL(remap_pfn_range);
1826
1827int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1828            unsigned long pgoff)
1829{
1830    unsigned int size = vma->vm_end - vma->vm_start;
1831
1832    if (!(vma->vm_flags & VM_USERMAP))
1833        return -EINVAL;
1834
1835    vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1836    vma->vm_end = vma->vm_start + size;
1837
1838    return 0;
1839}
1840EXPORT_SYMBOL(remap_vmalloc_range);
1841
1842unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1843    unsigned long len, unsigned long pgoff, unsigned long flags)
1844{
1845    return -ENOMEM;
1846}
1847
1848void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1849{
1850}
1851
1852void unmap_mapping_range(struct address_space *mapping,
1853             loff_t const holebegin, loff_t const holelen,
1854             int even_cows)
1855{
1856}
1857EXPORT_SYMBOL(unmap_mapping_range);
1858
1859/*
1860 * Check that a process has enough memory to allocate a new virtual
1861 * mapping. 0 means there is enough memory for the allocation to
1862 * succeed and -ENOMEM implies there is not.
1863 *
1864 * We currently support three overcommit policies, which are set via the
1865 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1866 *
1867 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1868 * Additional code 2002 Jul 20 by Robert Love.
1869 *
1870 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1871 *
1872 * Note this is a helper function intended to be used by LSMs which
1873 * wish to use this logic.
1874 */
1875int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1876{
1877    unsigned long free, allowed;
1878
1879    vm_acct_memory(pages);
1880
1881    /*
1882     * Sometimes we want to use more memory than we have
1883     */
1884    if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1885        return 0;
1886
1887    if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1888        unsigned long n;
1889
1890        free = global_page_state(NR_FILE_PAGES);
1891        free += nr_swap_pages;
1892
1893        /*
1894         * Any slabs which are created with the
1895         * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1896         * which are reclaimable, under pressure. The dentry
1897         * cache and most inode caches should fall into this
1898         */
1899        free += global_page_state(NR_SLAB_RECLAIMABLE);
1900
1901        /*
1902         * Leave the last 3% for root
1903         */
1904        if (!cap_sys_admin)
1905            free -= free / 32;
1906
1907        if (free > pages)
1908            return 0;
1909
1910        /*
1911         * nr_free_pages() is very expensive on large systems,
1912         * only call if we're about to fail.
1913         */
1914        n = nr_free_pages();
1915
1916        /*
1917         * Leave reserved pages. The pages are not for anonymous pages.
1918         */
1919        if (n <= totalreserve_pages)
1920            goto error;
1921        else
1922            n -= totalreserve_pages;
1923
1924        /*
1925         * Leave the last 3% for root
1926         */
1927        if (!cap_sys_admin)
1928            n -= n / 32;
1929        free += n;
1930
1931        if (free > pages)
1932            return 0;
1933
1934        goto error;
1935    }
1936
1937    allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1938    /*
1939     * Leave the last 3% for root
1940     */
1941    if (!cap_sys_admin)
1942        allowed -= allowed / 32;
1943    allowed += total_swap_pages;
1944
1945    /* Don't let a single process grow too big:
1946       leave 3% of the size of this process for other processes */
1947    if (mm)
1948        allowed -= mm->total_vm / 32;
1949
1950    if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1951        return 0;
1952
1953error:
1954    vm_unacct_memory(pages);
1955
1956    return -ENOMEM;
1957}
1958
1959int in_gate_area_no_mm(unsigned long addr)
1960{
1961    return 0;
1962}
1963
1964int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1965{
1966    BUG();
1967    return 0;
1968}
1969EXPORT_SYMBOL(filemap_fault);
1970
1971static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1972        unsigned long addr, void *buf, int len, int write)
1973{
1974    struct vm_area_struct *vma;
1975
1976    down_read(&mm->mmap_sem);
1977
1978    /* the access must start within one of the target process's mappings */
1979    vma = find_vma(mm, addr);
1980    if (vma) {
1981        /* don't overrun this mapping */
1982        if (addr + len >= vma->vm_end)
1983            len = vma->vm_end - addr;
1984
1985        /* only read or write mappings where it is permitted */
1986        if (write && vma->vm_flags & VM_MAYWRITE)
1987            copy_to_user_page(vma, NULL, addr,
1988                     (void *) addr, buf, len);
1989        else if (!write && vma->vm_flags & VM_MAYREAD)
1990            copy_from_user_page(vma, NULL, addr,
1991                        buf, (void *) addr, len);
1992        else
1993            len = 0;
1994    } else {
1995        len = 0;
1996    }
1997
1998    up_read(&mm->mmap_sem);
1999
2000    return len;
2001}
2002
2003/**
2004 * @access_remote_vm - access another process' address space
2005 * @mm: the mm_struct of the target address space
2006 * @addr: start address to access
2007 * @buf: source or destination buffer
2008 * @len: number of bytes to transfer
2009 * @write: whether the access is a write
2010 *
2011 * The caller must hold a reference on @mm.
2012 */
2013int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2014        void *buf, int len, int write)
2015{
2016    return __access_remote_vm(NULL, mm, addr, buf, len, write);
2017}
2018
2019/*
2020 * Access another process' address space.
2021 * - source/target buffer must be kernel space
2022 */
2023int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2024{
2025    struct mm_struct *mm;
2026
2027    if (addr + len < addr)
2028        return 0;
2029
2030    mm = get_task_mm(tsk);
2031    if (!mm)
2032        return 0;
2033
2034    len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2035
2036    mmput(mm);
2037    return len;
2038}
2039
2040/**
2041 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2042 * @inode: The inode to check
2043 * @size: The current filesize of the inode
2044 * @newsize: The proposed filesize of the inode
2045 *
2046 * Check the shared mappings on an inode on behalf of a shrinking truncate to
2047 * make sure that that any outstanding VMAs aren't broken and then shrink the
2048 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2049 * automatically grant mappings that are too large.
2050 */
2051int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2052                size_t newsize)
2053{
2054    struct vm_area_struct *vma;
2055    struct prio_tree_iter iter;
2056    struct vm_region *region;
2057    pgoff_t low, high;
2058    size_t r_size, r_top;
2059
2060    low = newsize >> PAGE_SHIFT;
2061    high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2062
2063    down_write(&nommu_region_sem);
2064
2065    /* search for VMAs that fall within the dead zone */
2066    vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2067                  low, high) {
2068        /* found one - only interested if it's shared out of the page
2069         * cache */
2070        if (vma->vm_flags & VM_SHARED) {
2071            up_write(&nommu_region_sem);
2072            return -ETXTBSY; /* not quite true, but near enough */
2073        }
2074    }
2075
2076    /* reduce any regions that overlap the dead zone - if in existence,
2077     * these will be pointed to by VMAs that don't overlap the dead zone
2078     *
2079     * we don't check for any regions that start beyond the EOF as there
2080     * shouldn't be any
2081     */
2082    vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2083                  0, ULONG_MAX) {
2084        if (!(vma->vm_flags & VM_SHARED))
2085            continue;
2086
2087        region = vma->vm_region;
2088        r_size = region->vm_top - region->vm_start;
2089        r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2090
2091        if (r_top > newsize) {
2092            region->vm_top -= r_top - newsize;
2093            if (region->vm_end > region->vm_top)
2094                region->vm_end = region->vm_top;
2095        }
2096    }
2097
2098    up_write(&nommu_region_sem);
2099    return 0;
2100}
2101

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