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/export.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/blkdev.h>
26#include <linux/backing-dev.h>
27#include <linux/mount.h>
28#include <linux/personality.h>
29#include <linux/security.h>
30#include <linux/syscalls.h>
31#include <linux/audit.h>
32
33#include <asm/uaccess.h>
34#include <asm/tlb.h>
35#include <asm/tlbflush.h>
36#include <asm/mmu_context.h>
37#include "internal.h"
38
39#if 0
40#define kenter(FMT, ...) \
41    printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
42#define kleave(FMT, ...) \
43    printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
44#define kdebug(FMT, ...) \
45    printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
46#else
47#define kenter(FMT, ...) \
48    no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
49#define kleave(FMT, ...) \
50    no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
51#define kdebug(FMT, ...) \
52    no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
53#endif
54
55void *high_memory;
56struct page *mem_map;
57unsigned long max_mapnr;
58unsigned long num_physpages;
59unsigned long highest_memmap_pfn;
60struct percpu_counter vm_committed_as;
61int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
62int sysctl_overcommit_ratio = 50; /* default is 50% */
63int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
64int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
65int heap_stack_gap = 0;
66
67atomic_long_t mmap_pages_allocated;
68
69EXPORT_SYMBOL(mem_map);
70EXPORT_SYMBOL(num_physpages);
71
72/* list of mapped, potentially shareable regions */
73static struct kmem_cache *vm_region_jar;
74struct rb_root nommu_region_tree = RB_ROOT;
75DECLARE_RWSEM(nommu_region_sem);
76
77const struct vm_operations_struct generic_file_vm_ops = {
78};
79
80/*
81 * Return the total memory allocated for this pointer, not
82 * just what the caller asked for.
83 *
84 * Doesn't have to be accurate, i.e. may have races.
85 */
86unsigned int kobjsize(const void *objp)
87{
88    struct page *page;
89
90    /*
91     * If the object we have should not have ksize performed on it,
92     * return size of 0
93     */
94    if (!objp || !virt_addr_valid(objp))
95        return 0;
96
97    page = virt_to_head_page(objp);
98
99    /*
100     * If the allocator sets PageSlab, we know the pointer came from
101     * kmalloc().
102     */
103    if (PageSlab(page))
104        return ksize(objp);
105
106    /*
107     * If it's not a compound page, see if we have a matching VMA
108     * region. This test is intentionally done in reverse order,
109     * so if there's no VMA, we still fall through and hand back
110     * PAGE_SIZE for 0-order pages.
111     */
112    if (!PageCompound(page)) {
113        struct vm_area_struct *vma;
114
115        vma = find_vma(current->mm, (unsigned long)objp);
116        if (vma)
117            return vma->vm_end - vma->vm_start;
118    }
119
120    /*
121     * The ksize() function is only guaranteed to work for pointers
122     * returned by kmalloc(). So handle arbitrary pointers here.
123     */
124    return PAGE_SIZE << compound_order(page);
125}
126
127int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
128             unsigned long start, int nr_pages, unsigned int foll_flags,
129             struct page **pages, struct vm_area_struct **vmas,
130             int *retry)
131{
132    struct vm_area_struct *vma;
133    unsigned long vm_flags;
134    int i;
135
136    /* calculate required read or write permissions.
137     * If FOLL_FORCE is set, we only require the "MAY" flags.
138     */
139    vm_flags = (foll_flags & FOLL_WRITE) ?
140            (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
141    vm_flags &= (foll_flags & FOLL_FORCE) ?
142            (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
143
144    for (i = 0; i < nr_pages; i++) {
145        vma = find_vma(mm, start);
146        if (!vma)
147            goto finish_or_fault;
148
149        /* protect what we can, including chardevs */
150        if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
151            !(vm_flags & vma->vm_flags))
152            goto finish_or_fault;
153
154        if (pages) {
155            pages[i] = virt_to_page(start);
156            if (pages[i])
157                page_cache_get(pages[i]);
158        }
159        if (vmas)
160            vmas[i] = vma;
161        start = (start + PAGE_SIZE) & PAGE_MASK;
162    }
163
164    return i;
165
166finish_or_fault:
167    return i ? : -EFAULT;
168}
169
170/*
171 * get a list of pages in an address range belonging to the specified process
172 * and indicate the VMA that covers each page
173 * - this is potentially dodgy as we may end incrementing the page count of a
174 * slab page or a secondary page from a compound page
175 * - don't permit access to VMAs that don't support it, such as I/O mappings
176 */
177int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
178    unsigned long start, int nr_pages, int write, int force,
179    struct page **pages, struct vm_area_struct **vmas)
180{
181    int flags = 0;
182
183    if (write)
184        flags |= FOLL_WRITE;
185    if (force)
186        flags |= FOLL_FORCE;
187
188    return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
189                NULL);
190}
191EXPORT_SYMBOL(get_user_pages);
192
193/**
194 * follow_pfn - look up PFN at a user virtual address
195 * @vma: memory mapping
196 * @address: user virtual address
197 * @pfn: location to store found PFN
198 *
199 * Only IO mappings and raw PFN mappings are allowed.
200 *
201 * Returns zero and the pfn at @pfn on success, -ve otherwise.
202 */
203int follow_pfn(struct vm_area_struct *vma, unsigned long address,
204    unsigned long *pfn)
205{
206    if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
207        return -EINVAL;
208
209    *pfn = address >> PAGE_SHIFT;
210    return 0;
211}
212EXPORT_SYMBOL(follow_pfn);
213
214DEFINE_RWLOCK(vmlist_lock);
215struct vm_struct *vmlist;
216
217void vfree(const void *addr)
218{
219    kfree(addr);
220}
221EXPORT_SYMBOL(vfree);
222
223void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
224{
225    /*
226     * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
227     * returns only a logical address.
228     */
229    return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
230}
231EXPORT_SYMBOL(__vmalloc);
232
233void *vmalloc_user(unsigned long size)
234{
235    void *ret;
236
237    ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
238            PAGE_KERNEL);
239    if (ret) {
240        struct vm_area_struct *vma;
241
242        down_write(&current->mm->mmap_sem);
243        vma = find_vma(current->mm, (unsigned long)ret);
244        if (vma)
245            vma->vm_flags |= VM_USERMAP;
246        up_write(&current->mm->mmap_sem);
247    }
248
249    return ret;
250}
251EXPORT_SYMBOL(vmalloc_user);
252
253struct page *vmalloc_to_page(const void *addr)
254{
255    return virt_to_page(addr);
256}
257EXPORT_SYMBOL(vmalloc_to_page);
258
259unsigned long vmalloc_to_pfn(const void *addr)
260{
261    return page_to_pfn(virt_to_page(addr));
262}
263EXPORT_SYMBOL(vmalloc_to_pfn);
264
265long vread(char *buf, char *addr, unsigned long count)
266{
267    memcpy(buf, addr, count);
268    return count;
269}
270
271long vwrite(char *buf, char *addr, unsigned long count)
272{
273    /* Don't allow overflow */
274    if ((unsigned long) addr + count < count)
275        count = -(unsigned long) addr;
276
277    memcpy(addr, buf, count);
278    return(count);
279}
280
281/*
282 * vmalloc - allocate virtually continguos memory
283 *
284 * @size: allocation size
285 *
286 * Allocate enough pages to cover @size from the page level
287 * allocator and map them into continguos kernel virtual space.
288 *
289 * For tight control over page level allocator and protection flags
290 * use __vmalloc() instead.
291 */
292void *vmalloc(unsigned long size)
293{
294       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
295}
296EXPORT_SYMBOL(vmalloc);
297
298/*
299 * vzalloc - allocate virtually continguos memory with zero fill
300 *
301 * @size: allocation size
302 *
303 * Allocate enough pages to cover @size from the page level
304 * allocator and map them into continguos kernel virtual space.
305 * The memory allocated is set to zero.
306 *
307 * For tight control over page level allocator and protection flags
308 * use __vmalloc() instead.
309 */
310void *vzalloc(unsigned long size)
311{
312    return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
313            PAGE_KERNEL);
314}
315EXPORT_SYMBOL(vzalloc);
316
317/**
318 * vmalloc_node - allocate memory on a specific node
319 * @size: allocation size
320 * @node: numa node
321 *
322 * Allocate enough pages to cover @size from the page level
323 * allocator and map them into contiguous kernel virtual space.
324 *
325 * For tight control over page level allocator and protection flags
326 * use __vmalloc() instead.
327 */
328void *vmalloc_node(unsigned long size, int node)
329{
330    return vmalloc(size);
331}
332EXPORT_SYMBOL(vmalloc_node);
333
334/**
335 * vzalloc_node - allocate memory on a specific node with zero fill
336 * @size: allocation size
337 * @node: numa node
338 *
339 * Allocate enough pages to cover @size from the page level
340 * allocator and map them into contiguous kernel virtual space.
341 * The memory allocated is set to zero.
342 *
343 * For tight control over page level allocator and protection flags
344 * use __vmalloc() instead.
345 */
346void *vzalloc_node(unsigned long size, int node)
347{
348    return vzalloc(size);
349}
350EXPORT_SYMBOL(vzalloc_node);
351
352#ifndef PAGE_KERNEL_EXEC
353# define PAGE_KERNEL_EXEC PAGE_KERNEL
354#endif
355
356/**
357 * vmalloc_exec - allocate virtually contiguous, executable memory
358 * @size: allocation size
359 *
360 * Kernel-internal function to allocate enough pages to cover @size
361 * the page level allocator and map them into contiguous and
362 * executable kernel virtual space.
363 *
364 * For tight control over page level allocator and protection flags
365 * use __vmalloc() instead.
366 */
367
368void *vmalloc_exec(unsigned long size)
369{
370    return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
371}
372
373/**
374 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
375 * @size: allocation size
376 *
377 * Allocate enough 32bit PA addressable pages to cover @size from the
378 * page level allocator and map them into continguos kernel virtual space.
379 */
380void *vmalloc_32(unsigned long size)
381{
382    return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
383}
384EXPORT_SYMBOL(vmalloc_32);
385
386/**
387 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
388 * @size: allocation size
389 *
390 * The resulting memory area is 32bit addressable and zeroed so it can be
391 * mapped to userspace without leaking data.
392 *
393 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
394 * remap_vmalloc_range() are permissible.
395 */
396void *vmalloc_32_user(unsigned long size)
397{
398    /*
399     * We'll have to sort out the ZONE_DMA bits for 64-bit,
400     * but for now this can simply use vmalloc_user() directly.
401     */
402    return vmalloc_user(size);
403}
404EXPORT_SYMBOL(vmalloc_32_user);
405
406void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
407{
408    BUG();
409    return NULL;
410}
411EXPORT_SYMBOL(vmap);
412
413void vunmap(const void *addr)
414{
415    BUG();
416}
417EXPORT_SYMBOL(vunmap);
418
419void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
420{
421    BUG();
422    return NULL;
423}
424EXPORT_SYMBOL(vm_map_ram);
425
426void vm_unmap_ram(const void *mem, unsigned int count)
427{
428    BUG();
429}
430EXPORT_SYMBOL(vm_unmap_ram);
431
432void vm_unmap_aliases(void)
433{
434}
435EXPORT_SYMBOL_GPL(vm_unmap_aliases);
436
437/*
438 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
439 * have one.
440 */
441void __attribute__((weak)) vmalloc_sync_all(void)
442{
443}
444
445/**
446 * alloc_vm_area - allocate a range of kernel address space
447 * @size: size of the area
448 *
449 * Returns: NULL on failure, vm_struct on success
450 *
451 * This function reserves a range of kernel address space, and
452 * allocates pagetables to map that range. No actual mappings
453 * are created. If the kernel address space is not shared
454 * between processes, it syncs the pagetable across all
455 * processes.
456 */
457struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
458{
459    BUG();
460    return NULL;
461}
462EXPORT_SYMBOL_GPL(alloc_vm_area);
463
464void free_vm_area(struct vm_struct *area)
465{
466    BUG();
467}
468EXPORT_SYMBOL_GPL(free_vm_area);
469
470int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
471           struct page *page)
472{
473    return -EINVAL;
474}
475EXPORT_SYMBOL(vm_insert_page);
476
477/*
478 * sys_brk() for the most part doesn't need the global kernel
479 * lock, except when an application is doing something nasty
480 * like trying to un-brk an area that has already been mapped
481 * to a regular file. in this case, the unmapping will need
482 * to invoke file system routines that need the global lock.
483 */
484SYSCALL_DEFINE1(brk, unsigned long, brk)
485{
486    struct mm_struct *mm = current->mm;
487
488    if (brk < mm->start_brk || brk > mm->context.end_brk)
489        return mm->brk;
490
491    if (mm->brk == brk)
492        return mm->brk;
493
494    /*
495     * Always allow shrinking brk
496     */
497    if (brk <= mm->brk) {
498        mm->brk = brk;
499        return brk;
500    }
501
502    /*
503     * Ok, looks good - let it rip.
504     */
505    flush_icache_range(mm->brk, brk);
506    return mm->brk = brk;
507}
508
509/*
510 * initialise the VMA and region record slabs
511 */
512void __init mmap_init(void)
513{
514    int ret;
515
516    ret = percpu_counter_init(&vm_committed_as, 0);
517    VM_BUG_ON(ret);
518    vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
519}
520
521/*
522 * validate the region tree
523 * - the caller must hold the region lock
524 */
525#ifdef CONFIG_DEBUG_NOMMU_REGIONS
526static noinline void validate_nommu_regions(void)
527{
528    struct vm_region *region, *last;
529    struct rb_node *p, *lastp;
530
531    lastp = rb_first(&nommu_region_tree);
532    if (!lastp)
533        return;
534
535    last = rb_entry(lastp, struct vm_region, vm_rb);
536    BUG_ON(unlikely(last->vm_end <= last->vm_start));
537    BUG_ON(unlikely(last->vm_top < last->vm_end));
538
539    while ((p = rb_next(lastp))) {
540        region = rb_entry(p, struct vm_region, vm_rb);
541        last = rb_entry(lastp, struct vm_region, vm_rb);
542
543        BUG_ON(unlikely(region->vm_end <= region->vm_start));
544        BUG_ON(unlikely(region->vm_top < region->vm_end));
545        BUG_ON(unlikely(region->vm_start < last->vm_top));
546
547        lastp = p;
548    }
549}
550#else
551static void validate_nommu_regions(void)
552{
553}
554#endif
555
556/*
557 * add a region into the global tree
558 */
559static void add_nommu_region(struct vm_region *region)
560{
561    struct vm_region *pregion;
562    struct rb_node **p, *parent;
563
564    validate_nommu_regions();
565
566    parent = NULL;
567    p = &nommu_region_tree.rb_node;
568    while (*p) {
569        parent = *p;
570        pregion = rb_entry(parent, struct vm_region, vm_rb);
571        if (region->vm_start < pregion->vm_start)
572            p = &(*p)->rb_left;
573        else if (region->vm_start > pregion->vm_start)
574            p = &(*p)->rb_right;
575        else if (pregion == region)
576            return;
577        else
578            BUG();
579    }
580
581    rb_link_node(&region->vm_rb, parent, p);
582    rb_insert_color(&region->vm_rb, &nommu_region_tree);
583
584    validate_nommu_regions();
585}
586
587/*
588 * delete a region from the global tree
589 */
590static void delete_nommu_region(struct vm_region *region)
591{
592    BUG_ON(!nommu_region_tree.rb_node);
593
594    validate_nommu_regions();
595    rb_erase(&region->vm_rb, &nommu_region_tree);
596    validate_nommu_regions();
597}
598
599/*
600 * free a contiguous series of pages
601 */
602static void free_page_series(unsigned long from, unsigned long to)
603{
604    for (; from < to; from += PAGE_SIZE) {
605        struct page *page = virt_to_page(from);
606
607        kdebug("- free %lx", from);
608        atomic_long_dec(&mmap_pages_allocated);
609        if (page_count(page) != 1)
610            kdebug("free page %p: refcount not one: %d",
611                   page, page_count(page));
612        put_page(page);
613    }
614}
615
616/*
617 * release a reference to a region
618 * - the caller must hold the region semaphore for writing, which this releases
619 * - the region may not have been added to the tree yet, in which case vm_top
620 * will equal vm_start
621 */
622static void __put_nommu_region(struct vm_region *region)
623    __releases(nommu_region_sem)
624{
625    kenter("%p{%d}", region, region->vm_usage);
626
627    BUG_ON(!nommu_region_tree.rb_node);
628
629    if (--region->vm_usage == 0) {
630        if (region->vm_top > region->vm_start)
631            delete_nommu_region(region);
632        up_write(&nommu_region_sem);
633
634        if (region->vm_file)
635            fput(region->vm_file);
636
637        /* IO memory and memory shared directly out of the pagecache
638         * from ramfs/tmpfs mustn't be released here */
639        if (region->vm_flags & VM_MAPPED_COPY) {
640            kdebug("free series");
641            free_page_series(region->vm_start, region->vm_top);
642        }
643        kmem_cache_free(vm_region_jar, region);
644    } else {
645        up_write(&nommu_region_sem);
646    }
647}
648
649/*
650 * release a reference to a region
651 */
652static void put_nommu_region(struct vm_region *region)
653{
654    down_write(&nommu_region_sem);
655    __put_nommu_region(region);
656}
657
658/*
659 * update protection on a vma
660 */
661static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
662{
663#ifdef CONFIG_MPU
664    struct mm_struct *mm = vma->vm_mm;
665    long start = vma->vm_start & PAGE_MASK;
666    while (start < vma->vm_end) {
667        protect_page(mm, start, flags);
668        start += PAGE_SIZE;
669    }
670    update_protections(mm);
671#endif
672}
673
674/*
675 * add a VMA into a process's mm_struct in the appropriate place in the list
676 * and tree and add to the address space's page tree also if not an anonymous
677 * page
678 * - should be called with mm->mmap_sem held writelocked
679 */
680static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
681{
682    struct vm_area_struct *pvma, *prev;
683    struct address_space *mapping;
684    struct rb_node **p, *parent, *rb_prev;
685
686    kenter(",%p", vma);
687
688    BUG_ON(!vma->vm_region);
689
690    mm->map_count++;
691    vma->vm_mm = mm;
692
693    protect_vma(vma, vma->vm_flags);
694
695    /* add the VMA to the mapping */
696    if (vma->vm_file) {
697        mapping = vma->vm_file->f_mapping;
698
699        mutex_lock(&mapping->i_mmap_mutex);
700        flush_dcache_mmap_lock(mapping);
701        vma_prio_tree_insert(vma, &mapping->i_mmap);
702        flush_dcache_mmap_unlock(mapping);
703        mutex_unlock(&mapping->i_mmap_mutex);
704    }
705
706    /* add the VMA to the tree */
707    parent = rb_prev = NULL;
708    p = &mm->mm_rb.rb_node;
709    while (*p) {
710        parent = *p;
711        pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
712
713        /* sort by: start addr, end addr, VMA struct addr in that order
714         * (the latter is necessary as we may get identical VMAs) */
715        if (vma->vm_start < pvma->vm_start)
716            p = &(*p)->rb_left;
717        else if (vma->vm_start > pvma->vm_start) {
718            rb_prev = parent;
719            p = &(*p)->rb_right;
720        } else if (vma->vm_end < pvma->vm_end)
721            p = &(*p)->rb_left;
722        else if (vma->vm_end > pvma->vm_end) {
723            rb_prev = parent;
724            p = &(*p)->rb_right;
725        } else if (vma < pvma)
726            p = &(*p)->rb_left;
727        else if (vma > pvma) {
728            rb_prev = parent;
729            p = &(*p)->rb_right;
730        } else
731            BUG();
732    }
733
734    rb_link_node(&vma->vm_rb, parent, p);
735    rb_insert_color(&vma->vm_rb, &mm->mm_rb);
736
737    /* add VMA to the VMA list also */
738    prev = NULL;
739    if (rb_prev)
740        prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
741
742    __vma_link_list(mm, vma, prev, parent);
743}
744
745/*
746 * delete a VMA from its owning mm_struct and address space
747 */
748static void delete_vma_from_mm(struct vm_area_struct *vma)
749{
750    struct address_space *mapping;
751    struct mm_struct *mm = vma->vm_mm;
752
753    kenter("%p", vma);
754
755    protect_vma(vma, 0);
756
757    mm->map_count--;
758    if (mm->mmap_cache == vma)
759        mm->mmap_cache = NULL;
760
761    /* remove the VMA from the mapping */
762    if (vma->vm_file) {
763        mapping = vma->vm_file->f_mapping;
764
765        mutex_lock(&mapping->i_mmap_mutex);
766        flush_dcache_mmap_lock(mapping);
767        vma_prio_tree_remove(vma, &mapping->i_mmap);
768        flush_dcache_mmap_unlock(mapping);
769        mutex_unlock(&mapping->i_mmap_mutex);
770    }
771
772    /* remove from the MM's tree and list */
773    rb_erase(&vma->vm_rb, &mm->mm_rb);
774
775    if (vma->vm_prev)
776        vma->vm_prev->vm_next = vma->vm_next;
777    else
778        mm->mmap = vma->vm_next;
779
780    if (vma->vm_next)
781        vma->vm_next->vm_prev = vma->vm_prev;
782}
783
784/*
785 * destroy a VMA record
786 */
787static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
788{
789    kenter("%p", vma);
790    if (vma->vm_ops && vma->vm_ops->close)
791        vma->vm_ops->close(vma);
792    if (vma->vm_file) {
793        fput(vma->vm_file);
794        if (vma->vm_flags & VM_EXECUTABLE)
795            removed_exe_file_vma(mm);
796    }
797    put_nommu_region(vma->vm_region);
798    kmem_cache_free(vm_area_cachep, vma);
799}
800
801/*
802 * look up the first VMA in which addr resides, NULL if none
803 * - should be called with mm->mmap_sem at least held readlocked
804 */
805struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
806{
807    struct vm_area_struct *vma;
808
809    /* check the cache first */
810    vma = mm->mmap_cache;
811    if (vma && vma->vm_start <= addr && vma->vm_end > addr)
812        return vma;
813
814    /* trawl the list (there may be multiple mappings in which addr
815     * resides) */
816    for (vma = mm->mmap; vma; vma = vma->vm_next) {
817        if (vma->vm_start > addr)
818            return NULL;
819        if (vma->vm_end > addr) {
820            mm->mmap_cache = vma;
821            return vma;
822        }
823    }
824
825    return NULL;
826}
827EXPORT_SYMBOL(find_vma);
828
829/*
830 * find a VMA
831 * - we don't extend stack VMAs under NOMMU conditions
832 */
833struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
834{
835    return find_vma(mm, addr);
836}
837
838/*
839 * expand a stack to a given address
840 * - not supported under NOMMU conditions
841 */
842int expand_stack(struct vm_area_struct *vma, unsigned long address)
843{
844    return -ENOMEM;
845}
846
847/*
848 * look up the first VMA exactly that exactly matches addr
849 * - should be called with mm->mmap_sem at least held readlocked
850 */
851static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
852                         unsigned long addr,
853                         unsigned long len)
854{
855    struct vm_area_struct *vma;
856    unsigned long end = addr + len;
857
858    /* check the cache first */
859    vma = mm->mmap_cache;
860    if (vma && vma->vm_start == addr && vma->vm_end == end)
861        return vma;
862
863    /* trawl the list (there may be multiple mappings in which addr
864     * resides) */
865    for (vma = mm->mmap; vma; vma = vma->vm_next) {
866        if (vma->vm_start < addr)
867            continue;
868        if (vma->vm_start > addr)
869            return NULL;
870        if (vma->vm_end == end) {
871            mm->mmap_cache = vma;
872            return vma;
873        }
874    }
875
876    return NULL;
877}
878
879/*
880 * determine whether a mapping should be permitted and, if so, what sort of
881 * mapping we're capable of supporting
882 */
883static int validate_mmap_request(struct file *file,
884                 unsigned long addr,
885                 unsigned long len,
886                 unsigned long prot,
887                 unsigned long flags,
888                 unsigned long pgoff,
889                 unsigned long *_capabilities)
890{
891    unsigned long capabilities, rlen;
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_mmap_addr(addr);
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) && current->ptrace)
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}
1472
1473SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1474        unsigned long, prot, unsigned long, flags,
1475        unsigned long, fd, unsigned long, pgoff)
1476{
1477    struct file *file = NULL;
1478    unsigned long retval = -EBADF;
1479
1480    audit_mmap_fd(fd, flags);
1481    if (!(flags & MAP_ANONYMOUS)) {
1482        file = fget(fd);
1483        if (!file)
1484            goto out;
1485    }
1486
1487    flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1488
1489    retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1490
1491    if (file)
1492        fput(file);
1493out:
1494    return retval;
1495}
1496
1497#ifdef __ARCH_WANT_SYS_OLD_MMAP
1498struct mmap_arg_struct {
1499    unsigned long addr;
1500    unsigned long len;
1501    unsigned long prot;
1502    unsigned long flags;
1503    unsigned long fd;
1504    unsigned long offset;
1505};
1506
1507SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1508{
1509    struct mmap_arg_struct a;
1510
1511    if (copy_from_user(&a, arg, sizeof(a)))
1512        return -EFAULT;
1513    if (a.offset & ~PAGE_MASK)
1514        return -EINVAL;
1515
1516    return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1517                  a.offset >> PAGE_SHIFT);
1518}
1519#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1520
1521/*
1522 * split a vma into two pieces at address 'addr', a new vma is allocated either
1523 * for the first part or the tail.
1524 */
1525int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1526          unsigned long addr, int new_below)
1527{
1528    struct vm_area_struct *new;
1529    struct vm_region *region;
1530    unsigned long npages;
1531
1532    kenter("");
1533
1534    /* we're only permitted to split anonymous regions (these should have
1535     * only a single usage on the region) */
1536    if (vma->vm_file)
1537        return -ENOMEM;
1538
1539    if (mm->map_count >= sysctl_max_map_count)
1540        return -ENOMEM;
1541
1542    region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1543    if (!region)
1544        return -ENOMEM;
1545
1546    new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1547    if (!new) {
1548        kmem_cache_free(vm_region_jar, region);
1549        return -ENOMEM;
1550    }
1551
1552    /* most fields are the same, copy all, and then fixup */
1553    *new = *vma;
1554    *region = *vma->vm_region;
1555    new->vm_region = region;
1556
1557    npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1558
1559    if (new_below) {
1560        region->vm_top = region->vm_end = new->vm_end = addr;
1561    } else {
1562        region->vm_start = new->vm_start = addr;
1563        region->vm_pgoff = new->vm_pgoff += npages;
1564    }
1565
1566    if (new->vm_ops && new->vm_ops->open)
1567        new->vm_ops->open(new);
1568
1569    delete_vma_from_mm(vma);
1570    down_write(&nommu_region_sem);
1571    delete_nommu_region(vma->vm_region);
1572    if (new_below) {
1573        vma->vm_region->vm_start = vma->vm_start = addr;
1574        vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1575    } else {
1576        vma->vm_region->vm_end = vma->vm_end = addr;
1577        vma->vm_region->vm_top = addr;
1578    }
1579    add_nommu_region(vma->vm_region);
1580    add_nommu_region(new->vm_region);
1581    up_write(&nommu_region_sem);
1582    add_vma_to_mm(mm, vma);
1583    add_vma_to_mm(mm, new);
1584    return 0;
1585}
1586
1587/*
1588 * shrink a VMA by removing the specified chunk from either the beginning or
1589 * the end
1590 */
1591static int shrink_vma(struct mm_struct *mm,
1592              struct vm_area_struct *vma,
1593              unsigned long from, unsigned long to)
1594{
1595    struct vm_region *region;
1596
1597    kenter("");
1598
1599    /* adjust the VMA's pointers, which may reposition it in the MM's tree
1600     * and list */
1601    delete_vma_from_mm(vma);
1602    if (from > vma->vm_start)
1603        vma->vm_end = from;
1604    else
1605        vma->vm_start = to;
1606    add_vma_to_mm(mm, vma);
1607
1608    /* cut the backing region down to size */
1609    region = vma->vm_region;
1610    BUG_ON(region->vm_usage != 1);
1611
1612    down_write(&nommu_region_sem);
1613    delete_nommu_region(region);
1614    if (from > region->vm_start) {
1615        to = region->vm_top;
1616        region->vm_top = region->vm_end = from;
1617    } else {
1618        region->vm_start = to;
1619    }
1620    add_nommu_region(region);
1621    up_write(&nommu_region_sem);
1622
1623    free_page_series(from, to);
1624    return 0;
1625}
1626
1627/*
1628 * release a mapping
1629 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1630 * VMA, though it need not cover the whole VMA
1631 */
1632int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1633{
1634    struct vm_area_struct *vma;
1635    unsigned long end;
1636    int ret;
1637
1638    kenter(",%lx,%zx", start, len);
1639
1640    len = PAGE_ALIGN(len);
1641    if (len == 0)
1642        return -EINVAL;
1643
1644    end = start + len;
1645
1646    /* find the first potentially overlapping VMA */
1647    vma = find_vma(mm, start);
1648    if (!vma) {
1649        static int limit = 0;
1650        if (limit < 5) {
1651            printk(KERN_WARNING
1652                   "munmap of memory not mmapped by process %d"
1653                   " (%s): 0x%lx-0x%lx\n",
1654                   current->pid, current->comm,
1655                   start, start + len - 1);
1656            limit++;
1657        }
1658        return -EINVAL;
1659    }
1660
1661    /* we're allowed to split an anonymous VMA but not a file-backed one */
1662    if (vma->vm_file) {
1663        do {
1664            if (start > vma->vm_start) {
1665                kleave(" = -EINVAL [miss]");
1666                return -EINVAL;
1667            }
1668            if (end == vma->vm_end)
1669                goto erase_whole_vma;
1670            vma = vma->vm_next;
1671        } while (vma);
1672        kleave(" = -EINVAL [split file]");
1673        return -EINVAL;
1674    } else {
1675        /* the chunk must be a subset of the VMA found */
1676        if (start == vma->vm_start && end == vma->vm_end)
1677            goto erase_whole_vma;
1678        if (start < vma->vm_start || end > vma->vm_end) {
1679            kleave(" = -EINVAL [superset]");
1680            return -EINVAL;
1681        }
1682        if (start & ~PAGE_MASK) {
1683            kleave(" = -EINVAL [unaligned start]");
1684            return -EINVAL;
1685        }
1686        if (end != vma->vm_end && end & ~PAGE_MASK) {
1687            kleave(" = -EINVAL [unaligned split]");
1688            return -EINVAL;
1689        }
1690        if (start != vma->vm_start && end != vma->vm_end) {
1691            ret = split_vma(mm, vma, start, 1);
1692            if (ret < 0) {
1693                kleave(" = %d [split]", ret);
1694                return ret;
1695            }
1696        }
1697        return shrink_vma(mm, vma, start, end);
1698    }
1699
1700erase_whole_vma:
1701    delete_vma_from_mm(vma);
1702    delete_vma(mm, vma);
1703    kleave(" = 0");
1704    return 0;
1705}
1706EXPORT_SYMBOL(do_munmap);
1707
1708int vm_munmap(unsigned long addr, size_t len)
1709{
1710    struct mm_struct *mm = current->mm;
1711    int ret;
1712
1713    down_write(&mm->mmap_sem);
1714    ret = do_munmap(mm, addr, len);
1715    up_write(&mm->mmap_sem);
1716    return ret;
1717}
1718EXPORT_SYMBOL(vm_munmap);
1719
1720SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1721{
1722    return vm_munmap(addr, len);
1723}
1724
1725/*
1726 * release all the mappings made in a process's VM space
1727 */
1728void exit_mmap(struct mm_struct *mm)
1729{
1730    struct vm_area_struct *vma;
1731
1732    if (!mm)
1733        return;
1734
1735    kenter("");
1736
1737    mm->total_vm = 0;
1738
1739    while ((vma = mm->mmap)) {
1740        mm->mmap = vma->vm_next;
1741        delete_vma_from_mm(vma);
1742        delete_vma(mm, vma);
1743        cond_resched();
1744    }
1745
1746    kleave("");
1747}
1748
1749unsigned long vm_brk(unsigned long addr, unsigned long len)
1750{
1751    return -ENOMEM;
1752}
1753
1754/*
1755 * expand (or shrink) an existing mapping, potentially moving it at the same
1756 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1757 *
1758 * under NOMMU conditions, we only permit changing a mapping's size, and only
1759 * as long as it stays within the region allocated by do_mmap_private() and the
1760 * block is not shareable
1761 *
1762 * MREMAP_FIXED is not supported under NOMMU conditions
1763 */
1764unsigned long do_mremap(unsigned long addr,
1765            unsigned long old_len, unsigned long new_len,
1766            unsigned long flags, unsigned long new_addr)
1767{
1768    struct vm_area_struct *vma;
1769
1770    /* insanity checks first */
1771    old_len = PAGE_ALIGN(old_len);
1772    new_len = PAGE_ALIGN(new_len);
1773    if (old_len == 0 || new_len == 0)
1774        return (unsigned long) -EINVAL;
1775
1776    if (addr & ~PAGE_MASK)
1777        return -EINVAL;
1778
1779    if (flags & MREMAP_FIXED && new_addr != addr)
1780        return (unsigned long) -EINVAL;
1781
1782    vma = find_vma_exact(current->mm, addr, old_len);
1783    if (!vma)
1784        return (unsigned long) -EINVAL;
1785
1786    if (vma->vm_end != vma->vm_start + old_len)
1787        return (unsigned long) -EFAULT;
1788
1789    if (vma->vm_flags & VM_MAYSHARE)
1790        return (unsigned long) -EPERM;
1791
1792    if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1793        return (unsigned long) -ENOMEM;
1794
1795    /* all checks complete - do it */
1796    vma->vm_end = vma->vm_start + new_len;
1797    return vma->vm_start;
1798}
1799EXPORT_SYMBOL(do_mremap);
1800
1801SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1802        unsigned long, new_len, unsigned long, flags,
1803        unsigned long, new_addr)
1804{
1805    unsigned long ret;
1806
1807    down_write(&current->mm->mmap_sem);
1808    ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1809    up_write(&current->mm->mmap_sem);
1810    return ret;
1811}
1812
1813struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1814            unsigned int foll_flags)
1815{
1816    return NULL;
1817}
1818
1819int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1820        unsigned long pfn, unsigned long size, pgprot_t prot)
1821{
1822    if (addr != (pfn << PAGE_SHIFT))
1823        return -EINVAL;
1824
1825    vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
1826    return 0;
1827}
1828EXPORT_SYMBOL(remap_pfn_range);
1829
1830int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1831            unsigned long pgoff)
1832{
1833    unsigned int size = vma->vm_end - vma->vm_start;
1834
1835    if (!(vma->vm_flags & VM_USERMAP))
1836        return -EINVAL;
1837
1838    vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1839    vma->vm_end = vma->vm_start + size;
1840
1841    return 0;
1842}
1843EXPORT_SYMBOL(remap_vmalloc_range);
1844
1845unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1846    unsigned long len, unsigned long pgoff, unsigned long flags)
1847{
1848    return -ENOMEM;
1849}
1850
1851void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1852{
1853}
1854
1855void unmap_mapping_range(struct address_space *mapping,
1856             loff_t const holebegin, loff_t const holelen,
1857             int even_cows)
1858{
1859}
1860EXPORT_SYMBOL(unmap_mapping_range);
1861
1862/*
1863 * Check that a process has enough memory to allocate a new virtual
1864 * mapping. 0 means there is enough memory for the allocation to
1865 * succeed and -ENOMEM implies there is not.
1866 *
1867 * We currently support three overcommit policies, which are set via the
1868 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1869 *
1870 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1871 * Additional code 2002 Jul 20 by Robert Love.
1872 *
1873 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1874 *
1875 * Note this is a helper function intended to be used by LSMs which
1876 * wish to use this logic.
1877 */
1878int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1879{
1880    unsigned long free, allowed;
1881
1882    vm_acct_memory(pages);
1883
1884    /*
1885     * Sometimes we want to use more memory than we have
1886     */
1887    if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1888        return 0;
1889
1890    if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1891        free = global_page_state(NR_FREE_PAGES);
1892        free += global_page_state(NR_FILE_PAGES);
1893
1894        /*
1895         * shmem pages shouldn't be counted as free in this
1896         * case, they can't be purged, only swapped out, and
1897         * that won't affect the overall amount of available
1898         * memory in the system.
1899         */
1900        free -= global_page_state(NR_SHMEM);
1901
1902        free += nr_swap_pages;
1903
1904        /*
1905         * Any slabs which are created with the
1906         * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1907         * which are reclaimable, under pressure. The dentry
1908         * cache and most inode caches should fall into this
1909         */
1910        free += global_page_state(NR_SLAB_RECLAIMABLE);
1911
1912        /*
1913         * Leave reserved pages. The pages are not for anonymous pages.
1914         */
1915        if (free <= totalreserve_pages)
1916            goto error;
1917        else
1918            free -= totalreserve_pages;
1919
1920        /*
1921         * Leave the last 3% for root
1922         */
1923        if (!cap_sys_admin)
1924            free -= free / 32;
1925
1926        if (free > pages)
1927            return 0;
1928
1929        goto error;
1930    }
1931
1932    allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1933    /*
1934     * Leave the last 3% for root
1935     */
1936    if (!cap_sys_admin)
1937        allowed -= allowed / 32;
1938    allowed += total_swap_pages;
1939
1940    /* Don't let a single process grow too big:
1941       leave 3% of the size of this process for other processes */
1942    if (mm)
1943        allowed -= mm->total_vm / 32;
1944
1945    if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1946        return 0;
1947
1948error:
1949    vm_unacct_memory(pages);
1950
1951    return -ENOMEM;
1952}
1953
1954int in_gate_area_no_mm(unsigned long addr)
1955{
1956    return 0;
1957}
1958
1959int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1960{
1961    BUG();
1962    return 0;
1963}
1964EXPORT_SYMBOL(filemap_fault);
1965
1966static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1967        unsigned long addr, void *buf, int len, int write)
1968{
1969    struct vm_area_struct *vma;
1970
1971    down_read(&mm->mmap_sem);
1972
1973    /* the access must start within one of the target process's mappings */
1974    vma = find_vma(mm, addr);
1975    if (vma) {
1976        /* don't overrun this mapping */
1977        if (addr + len >= vma->vm_end)
1978            len = vma->vm_end - addr;
1979
1980        /* only read or write mappings where it is permitted */
1981        if (write && vma->vm_flags & VM_MAYWRITE)
1982            copy_to_user_page(vma, NULL, addr,
1983                     (void *) addr, buf, len);
1984        else if (!write && vma->vm_flags & VM_MAYREAD)
1985            copy_from_user_page(vma, NULL, addr,
1986                        buf, (void *) addr, len);
1987        else
1988            len = 0;
1989    } else {
1990        len = 0;
1991    }
1992
1993    up_read(&mm->mmap_sem);
1994
1995    return len;
1996}
1997
1998/**
1999 * @access_remote_vm - access another process' address space
2000 * @mm: the mm_struct of the target address space
2001 * @addr: start address to access
2002 * @buf: source or destination buffer
2003 * @len: number of bytes to transfer
2004 * @write: whether the access is a write
2005 *
2006 * The caller must hold a reference on @mm.
2007 */
2008int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2009        void *buf, int len, int write)
2010{
2011    return __access_remote_vm(NULL, mm, addr, buf, len, write);
2012}
2013
2014/*
2015 * Access another process' address space.
2016 * - source/target buffer must be kernel space
2017 */
2018int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2019{
2020    struct mm_struct *mm;
2021
2022    if (addr + len < addr)
2023        return 0;
2024
2025    mm = get_task_mm(tsk);
2026    if (!mm)
2027        return 0;
2028
2029    len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2030
2031    mmput(mm);
2032    return len;
2033}
2034
2035/**
2036 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2037 * @inode: The inode to check
2038 * @size: The current filesize of the inode
2039 * @newsize: The proposed filesize of the inode
2040 *
2041 * Check the shared mappings on an inode on behalf of a shrinking truncate to
2042 * make sure that that any outstanding VMAs aren't broken and then shrink the
2043 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2044 * automatically grant mappings that are too large.
2045 */
2046int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2047                size_t newsize)
2048{
2049    struct vm_area_struct *vma;
2050    struct prio_tree_iter iter;
2051    struct vm_region *region;
2052    pgoff_t low, high;
2053    size_t r_size, r_top;
2054
2055    low = newsize >> PAGE_SHIFT;
2056    high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2057
2058    down_write(&nommu_region_sem);
2059    mutex_lock(&inode->i_mapping->i_mmap_mutex);
2060
2061    /* search for VMAs that fall within the dead zone */
2062    vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2063                  low, high) {
2064        /* found one - only interested if it's shared out of the page
2065         * cache */
2066        if (vma->vm_flags & VM_SHARED) {
2067            mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2068            up_write(&nommu_region_sem);
2069            return -ETXTBSY; /* not quite true, but near enough */
2070        }
2071    }
2072
2073    /* reduce any regions that overlap the dead zone - if in existence,
2074     * these will be pointed to by VMAs that don't overlap the dead zone
2075     *
2076     * we don't check for any regions that start beyond the EOF as there
2077     * shouldn't be any
2078     */
2079    vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
2080                  0, ULONG_MAX) {
2081        if (!(vma->vm_flags & VM_SHARED))
2082            continue;
2083
2084        region = vma->vm_region;
2085        r_size = region->vm_top - region->vm_start;
2086        r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2087
2088        if (r_top > newsize) {
2089            region->vm_top -= r_top - newsize;
2090            if (region->vm_end > region->vm_top)
2091                region->vm_end = region->vm_top;
2092        }
2093    }
2094
2095    mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2096    up_write(&nommu_region_sem);
2097    return 0;
2098}
2099

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