[PATCH] mm: follow_page with inner ptlock
[linux-2.6.git] / 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) 2004-2005 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  */
14
15 #include <linux/mm.h>
16 #include <linux/mman.h>
17 #include <linux/swap.h>
18 #include <linux/file.h>
19 #include <linux/highmem.h>
20 #include <linux/pagemap.h>
21 #include <linux/slab.h>
22 #include <linux/vmalloc.h>
23 #include <linux/ptrace.h>
24 #include <linux/blkdev.h>
25 #include <linux/backing-dev.h>
26 #include <linux/mount.h>
27 #include <linux/personality.h>
28 #include <linux/security.h>
29 #include <linux/syscalls.h>
30
31 #include <asm/uaccess.h>
32 #include <asm/tlb.h>
33 #include <asm/tlbflush.h>
34
35 void *high_memory;
36 struct page *mem_map;
37 unsigned long max_mapnr;
38 unsigned long num_physpages;
39 unsigned long askedalloc, realalloc;
40 atomic_t vm_committed_space = ATOMIC_INIT(0);
41 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
42 int sysctl_overcommit_ratio = 50; /* default is 50% */
43 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
44 int heap_stack_gap = 0;
45
46 EXPORT_SYMBOL(mem_map);
47 EXPORT_SYMBOL(sysctl_max_map_count);
48 EXPORT_SYMBOL(sysctl_overcommit_memory);
49 EXPORT_SYMBOL(sysctl_overcommit_ratio);
50 EXPORT_SYMBOL(vm_committed_space);
51 EXPORT_SYMBOL(__vm_enough_memory);
52
53 /* list of shareable VMAs */
54 struct rb_root nommu_vma_tree = RB_ROOT;
55 DECLARE_RWSEM(nommu_vma_sem);
56
57 struct vm_operations_struct generic_file_vm_ops = {
58 };
59
60 EXPORT_SYMBOL(vmalloc);
61 EXPORT_SYMBOL(vfree);
62 EXPORT_SYMBOL(vmalloc_to_page);
63 EXPORT_SYMBOL(vmalloc_32);
64
65 /*
66  * Handle all mappings that got truncated by a "truncate()"
67  * system call.
68  *
69  * NOTE! We have to be ready to update the memory sharing
70  * between the file and the memory map for a potential last
71  * incomplete page.  Ugly, but necessary.
72  */
73 int vmtruncate(struct inode *inode, loff_t offset)
74 {
75         struct address_space *mapping = inode->i_mapping;
76         unsigned long limit;
77
78         if (inode->i_size < offset)
79                 goto do_expand;
80         i_size_write(inode, offset);
81
82         truncate_inode_pages(mapping, offset);
83         goto out_truncate;
84
85 do_expand:
86         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
87         if (limit != RLIM_INFINITY && offset > limit)
88                 goto out_sig;
89         if (offset > inode->i_sb->s_maxbytes)
90                 goto out;
91         i_size_write(inode, offset);
92
93 out_truncate:
94         if (inode->i_op && inode->i_op->truncate)
95                 inode->i_op->truncate(inode);
96         return 0;
97 out_sig:
98         send_sig(SIGXFSZ, current, 0);
99 out:
100         return -EFBIG;
101 }
102
103 EXPORT_SYMBOL(vmtruncate);
104
105 /*
106  * Return the total memory allocated for this pointer, not
107  * just what the caller asked for.
108  *
109  * Doesn't have to be accurate, i.e. may have races.
110  */
111 unsigned int kobjsize(const void *objp)
112 {
113         struct page *page;
114
115         if (!objp || !((page = virt_to_page(objp))))
116                 return 0;
117
118         if (PageSlab(page))
119                 return ksize(objp);
120
121         BUG_ON(page->index < 0);
122         BUG_ON(page->index >= MAX_ORDER);
123
124         return (PAGE_SIZE << page->index);
125 }
126
127 /*
128  * The nommu dodgy version :-)
129  */
130 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
131         unsigned long start, int len, int write, int force,
132         struct page **pages, struct vm_area_struct **vmas)
133 {
134         int i;
135         static struct vm_area_struct dummy_vma;
136
137         for (i = 0; i < len; i++) {
138                 if (pages) {
139                         pages[i] = virt_to_page(start);
140                         if (pages[i])
141                                 page_cache_get(pages[i]);
142                 }
143                 if (vmas)
144                         vmas[i] = &dummy_vma;
145                 start += PAGE_SIZE;
146         }
147         return(i);
148 }
149
150 EXPORT_SYMBOL(get_user_pages);
151
152 DEFINE_RWLOCK(vmlist_lock);
153 struct vm_struct *vmlist;
154
155 void vfree(void *addr)
156 {
157         kfree(addr);
158 }
159
160 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
161 {
162         /*
163          * kmalloc doesn't like __GFP_HIGHMEM for some reason
164          */
165         return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM);
166 }
167
168 struct page * vmalloc_to_page(void *addr)
169 {
170         return virt_to_page(addr);
171 }
172
173 unsigned long vmalloc_to_pfn(void *addr)
174 {
175         return page_to_pfn(virt_to_page(addr));
176 }
177
178
179 long vread(char *buf, char *addr, unsigned long count)
180 {
181         memcpy(buf, addr, count);
182         return count;
183 }
184
185 long vwrite(char *buf, char *addr, unsigned long count)
186 {
187         /* Don't allow overflow */
188         if ((unsigned long) addr + count < count)
189                 count = -(unsigned long) addr;
190
191         memcpy(addr, buf, count);
192         return(count);
193 }
194
195 /*
196  *      vmalloc  -  allocate virtually continguos memory
197  *
198  *      @size:          allocation size
199  *
200  *      Allocate enough pages to cover @size from the page level
201  *      allocator and map them into continguos kernel virtual space.
202  *
203  *      For tight cotrol over page level allocator and protection flags
204  *      use __vmalloc() instead.
205  */
206 void *vmalloc(unsigned long size)
207 {
208        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
209 }
210
211 /*
212  *      vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
213  *
214  *      @size:          allocation size
215  *
216  *      Allocate enough 32bit PA addressable pages to cover @size from the
217  *      page level allocator and map them into continguos kernel virtual space.
218  */
219 void *vmalloc_32(unsigned long size)
220 {
221         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
222 }
223
224 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
225 {
226         BUG();
227         return NULL;
228 }
229
230 void vunmap(void *addr)
231 {
232         BUG();
233 }
234
235 /*
236  *  sys_brk() for the most part doesn't need the global kernel
237  *  lock, except when an application is doing something nasty
238  *  like trying to un-brk an area that has already been mapped
239  *  to a regular file.  in this case, the unmapping will need
240  *  to invoke file system routines that need the global lock.
241  */
242 asmlinkage unsigned long sys_brk(unsigned long brk)
243 {
244         struct mm_struct *mm = current->mm;
245
246         if (brk < mm->start_brk || brk > mm->context.end_brk)
247                 return mm->brk;
248
249         if (mm->brk == brk)
250                 return mm->brk;
251
252         /*
253          * Always allow shrinking brk
254          */
255         if (brk <= mm->brk) {
256                 mm->brk = brk;
257                 return brk;
258         }
259
260         /*
261          * Ok, looks good - let it rip.
262          */
263         return mm->brk = brk;
264 }
265
266 #ifdef DEBUG
267 static void show_process_blocks(void)
268 {
269         struct vm_list_struct *vml;
270
271         printk("Process blocks %d:", current->pid);
272
273         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
274                 printk(" %p: %p", vml, vml->vma);
275                 if (vml->vma)
276                         printk(" (%d @%lx #%d)",
277                                kobjsize((void *) vml->vma->vm_start),
278                                vml->vma->vm_start,
279                                atomic_read(&vml->vma->vm_usage));
280                 printk(vml->next ? " ->" : ".\n");
281         }
282 }
283 #endif /* DEBUG */
284
285 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
286 {
287         struct vm_area_struct *vma;
288         struct rb_node *n = nommu_vma_tree.rb_node;
289
290         while (n) {
291                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
292
293                 if (start < vma->vm_start)
294                         n = n->rb_left;
295                 else if (start > vma->vm_start)
296                         n = n->rb_right;
297                 else
298                         return vma;
299         }
300
301         return NULL;
302 }
303
304 static void add_nommu_vma(struct vm_area_struct *vma)
305 {
306         struct vm_area_struct *pvma;
307         struct address_space *mapping;
308         struct rb_node **p = &nommu_vma_tree.rb_node;
309         struct rb_node *parent = NULL;
310
311         /* add the VMA to the mapping */
312         if (vma->vm_file) {
313                 mapping = vma->vm_file->f_mapping;
314
315                 flush_dcache_mmap_lock(mapping);
316                 vma_prio_tree_insert(vma, &mapping->i_mmap);
317                 flush_dcache_mmap_unlock(mapping);
318         }
319
320         /* add the VMA to the master list */
321         while (*p) {
322                 parent = *p;
323                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
324
325                 if (vma->vm_start < pvma->vm_start) {
326                         p = &(*p)->rb_left;
327                 }
328                 else if (vma->vm_start > pvma->vm_start) {
329                         p = &(*p)->rb_right;
330                 }
331                 else {
332                         /* mappings are at the same address - this can only
333                          * happen for shared-mem chardevs and shared file
334                          * mappings backed by ramfs/tmpfs */
335                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
336
337                         if (vma < pvma)
338                                 p = &(*p)->rb_left;
339                         else if (vma > pvma)
340                                 p = &(*p)->rb_right;
341                         else
342                                 BUG();
343                 }
344         }
345
346         rb_link_node(&vma->vm_rb, parent, p);
347         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
348 }
349
350 static void delete_nommu_vma(struct vm_area_struct *vma)
351 {
352         struct address_space *mapping;
353
354         /* remove the VMA from the mapping */
355         if (vma->vm_file) {
356                 mapping = vma->vm_file->f_mapping;
357
358                 flush_dcache_mmap_lock(mapping);
359                 vma_prio_tree_remove(vma, &mapping->i_mmap);
360                 flush_dcache_mmap_unlock(mapping);
361         }
362
363         /* remove from the master list */
364         rb_erase(&vma->vm_rb, &nommu_vma_tree);
365 }
366
367 /*
368  * determine whether a mapping should be permitted and, if so, what sort of
369  * mapping we're capable of supporting
370  */
371 static int validate_mmap_request(struct file *file,
372                                  unsigned long addr,
373                                  unsigned long len,
374                                  unsigned long prot,
375                                  unsigned long flags,
376                                  unsigned long pgoff,
377                                  unsigned long *_capabilities)
378 {
379         unsigned long capabilities;
380         unsigned long reqprot = prot;
381         int ret;
382
383         /* do the simple checks first */
384         if (flags & MAP_FIXED || addr) {
385                 printk(KERN_DEBUG
386                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
387                        current->pid);
388                 return -EINVAL;
389         }
390
391         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
392             (flags & MAP_TYPE) != MAP_SHARED)
393                 return -EINVAL;
394
395         if (PAGE_ALIGN(len) == 0)
396                 return addr;
397
398         if (len > TASK_SIZE)
399                 return -EINVAL;
400
401         /* offset overflow? */
402         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
403                 return -EINVAL;
404
405         if (file) {
406                 /* validate file mapping requests */
407                 struct address_space *mapping;
408
409                 /* files must support mmap */
410                 if (!file->f_op || !file->f_op->mmap)
411                         return -ENODEV;
412
413                 /* work out if what we've got could possibly be shared
414                  * - we support chardevs that provide their own "memory"
415                  * - we support files/blockdevs that are memory backed
416                  */
417                 mapping = file->f_mapping;
418                 if (!mapping)
419                         mapping = file->f_dentry->d_inode->i_mapping;
420
421                 capabilities = 0;
422                 if (mapping && mapping->backing_dev_info)
423                         capabilities = mapping->backing_dev_info->capabilities;
424
425                 if (!capabilities) {
426                         /* no explicit capabilities set, so assume some
427                          * defaults */
428                         switch (file->f_dentry->d_inode->i_mode & S_IFMT) {
429                         case S_IFREG:
430                         case S_IFBLK:
431                                 capabilities = BDI_CAP_MAP_COPY;
432                                 break;
433
434                         case S_IFCHR:
435                                 capabilities =
436                                         BDI_CAP_MAP_DIRECT |
437                                         BDI_CAP_READ_MAP |
438                                         BDI_CAP_WRITE_MAP;
439                                 break;
440
441                         default:
442                                 return -EINVAL;
443                         }
444                 }
445
446                 /* eliminate any capabilities that we can't support on this
447                  * device */
448                 if (!file->f_op->get_unmapped_area)
449                         capabilities &= ~BDI_CAP_MAP_DIRECT;
450                 if (!file->f_op->read)
451                         capabilities &= ~BDI_CAP_MAP_COPY;
452
453                 if (flags & MAP_SHARED) {
454                         /* do checks for writing, appending and locking */
455                         if ((prot & PROT_WRITE) &&
456                             !(file->f_mode & FMODE_WRITE))
457                                 return -EACCES;
458
459                         if (IS_APPEND(file->f_dentry->d_inode) &&
460                             (file->f_mode & FMODE_WRITE))
461                                 return -EACCES;
462
463                         if (locks_verify_locked(file->f_dentry->d_inode))
464                                 return -EAGAIN;
465
466                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
467                                 return -ENODEV;
468
469                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
470                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
471                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
472                             ) {
473                                 printk("MAP_SHARED not completely supported on !MMU\n");
474                                 return -EINVAL;
475                         }
476
477                         /* we mustn't privatise shared mappings */
478                         capabilities &= ~BDI_CAP_MAP_COPY;
479                 }
480                 else {
481                         /* we're going to read the file into private memory we
482                          * allocate */
483                         if (!(capabilities & BDI_CAP_MAP_COPY))
484                                 return -ENODEV;
485
486                         /* we don't permit a private writable mapping to be
487                          * shared with the backing device */
488                         if (prot & PROT_WRITE)
489                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
490                 }
491
492                 /* handle executable mappings and implied executable
493                  * mappings */
494                 if (file->f_vfsmnt->mnt_flags & MNT_NOEXEC) {
495                         if (prot & PROT_EXEC)
496                                 return -EPERM;
497                 }
498                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
499                         /* handle implication of PROT_EXEC by PROT_READ */
500                         if (current->personality & READ_IMPLIES_EXEC) {
501                                 if (capabilities & BDI_CAP_EXEC_MAP)
502                                         prot |= PROT_EXEC;
503                         }
504                 }
505                 else if ((prot & PROT_READ) &&
506                          (prot & PROT_EXEC) &&
507                          !(capabilities & BDI_CAP_EXEC_MAP)
508                          ) {
509                         /* backing file is not executable, try to copy */
510                         capabilities &= ~BDI_CAP_MAP_DIRECT;
511                 }
512         }
513         else {
514                 /* anonymous mappings are always memory backed and can be
515                  * privately mapped
516                  */
517                 capabilities = BDI_CAP_MAP_COPY;
518
519                 /* handle PROT_EXEC implication by PROT_READ */
520                 if ((prot & PROT_READ) &&
521                     (current->personality & READ_IMPLIES_EXEC))
522                         prot |= PROT_EXEC;
523         }
524
525         /* allow the security API to have its say */
526         ret = security_file_mmap(file, reqprot, prot, flags);
527         if (ret < 0)
528                 return ret;
529
530         /* looks okay */
531         *_capabilities = capabilities;
532         return 0;
533 }
534
535 /*
536  * we've determined that we can make the mapping, now translate what we
537  * now know into VMA flags
538  */
539 static unsigned long determine_vm_flags(struct file *file,
540                                         unsigned long prot,
541                                         unsigned long flags,
542                                         unsigned long capabilities)
543 {
544         unsigned long vm_flags;
545
546         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
547         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
548         /* vm_flags |= mm->def_flags; */
549
550         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
551                 /* attempt to share read-only copies of mapped file chunks */
552                 if (file && !(prot & PROT_WRITE))
553                         vm_flags |= VM_MAYSHARE;
554         }
555         else {
556                 /* overlay a shareable mapping on the backing device or inode
557                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
558                  * romfs/cramfs */
559                 if (flags & MAP_SHARED)
560                         vm_flags |= VM_MAYSHARE | VM_SHARED;
561                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
562                         vm_flags |= VM_MAYSHARE;
563         }
564
565         /* refuse to let anyone share private mappings with this process if
566          * it's being traced - otherwise breakpoints set in it may interfere
567          * with another untraced process
568          */
569         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
570                 vm_flags &= ~VM_MAYSHARE;
571
572         return vm_flags;
573 }
574
575 /*
576  * set up a shared mapping on a file
577  */
578 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
579 {
580         int ret;
581
582         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
583         if (ret != -ENOSYS)
584                 return ret;
585
586         /* getting an ENOSYS error indicates that direct mmap isn't
587          * possible (as opposed to tried but failed) so we'll fall
588          * through to making a private copy of the data and mapping
589          * that if we can */
590         return -ENODEV;
591 }
592
593 /*
594  * set up a private mapping or an anonymous shared mapping
595  */
596 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
597 {
598         void *base;
599         int ret;
600
601         /* invoke the file's mapping function so that it can keep track of
602          * shared mappings on devices or memory
603          * - VM_MAYSHARE will be set if it may attempt to share
604          */
605         if (vma->vm_file) {
606                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
607                 if (ret != -ENOSYS) {
608                         /* shouldn't return success if we're not sharing */
609                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
610                         return ret; /* success or a real error */
611                 }
612
613                 /* getting an ENOSYS error indicates that direct mmap isn't
614                  * possible (as opposed to tried but failed) so we'll try to
615                  * make a private copy of the data and map that instead */
616         }
617
618         /* allocate some memory to hold the mapping
619          * - note that this may not return a page-aligned address if the object
620          *   we're allocating is smaller than a page
621          */
622         base = kmalloc(len, GFP_KERNEL);
623         if (!base)
624                 goto enomem;
625
626         vma->vm_start = (unsigned long) base;
627         vma->vm_end = vma->vm_start + len;
628         vma->vm_flags |= VM_MAPPED_COPY;
629
630 #ifdef WARN_ON_SLACK
631         if (len + WARN_ON_SLACK <= kobjsize(result))
632                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
633                        len, current->pid, kobjsize(result) - len);
634 #endif
635
636         if (vma->vm_file) {
637                 /* read the contents of a file into the copy */
638                 mm_segment_t old_fs;
639                 loff_t fpos;
640
641                 fpos = vma->vm_pgoff;
642                 fpos <<= PAGE_SHIFT;
643
644                 old_fs = get_fs();
645                 set_fs(KERNEL_DS);
646                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
647                 set_fs(old_fs);
648
649                 if (ret < 0)
650                         goto error_free;
651
652                 /* clear the last little bit */
653                 if (ret < len)
654                         memset(base + ret, 0, len - ret);
655
656         } else {
657                 /* if it's an anonymous mapping, then just clear it */
658                 memset(base, 0, len);
659         }
660
661         return 0;
662
663 error_free:
664         kfree(base);
665         vma->vm_start = 0;
666         return ret;
667
668 enomem:
669         printk("Allocation of length %lu from process %d failed\n",
670                len, current->pid);
671         show_free_areas();
672         return -ENOMEM;
673 }
674
675 /*
676  * handle mapping creation for uClinux
677  */
678 unsigned long do_mmap_pgoff(struct file *file,
679                             unsigned long addr,
680                             unsigned long len,
681                             unsigned long prot,
682                             unsigned long flags,
683                             unsigned long pgoff)
684 {
685         struct vm_list_struct *vml = NULL;
686         struct vm_area_struct *vma = NULL;
687         struct rb_node *rb;
688         unsigned long capabilities, vm_flags;
689         void *result;
690         int ret;
691
692         /* decide whether we should attempt the mapping, and if so what sort of
693          * mapping */
694         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
695                                     &capabilities);
696         if (ret < 0)
697                 return ret;
698
699         /* we've determined that we can make the mapping, now translate what we
700          * now know into VMA flags */
701         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
702
703         /* we're going to need to record the mapping if it works */
704         vml = kmalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
705         if (!vml)
706                 goto error_getting_vml;
707         memset(vml, 0, sizeof(*vml));
708
709         down_write(&nommu_vma_sem);
710
711         /* if we want to share, we need to check for VMAs created by other
712          * mmap() calls that overlap with our proposed mapping
713          * - we can only share with an exact match on most regular files
714          * - shared mappings on character devices and memory backed files are
715          *   permitted to overlap inexactly as far as we are concerned for in
716          *   these cases, sharing is handled in the driver or filesystem rather
717          *   than here
718          */
719         if (vm_flags & VM_MAYSHARE) {
720                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
721                 unsigned long vmpglen;
722
723                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
724                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
725
726                         if (!(vma->vm_flags & VM_MAYSHARE))
727                                 continue;
728
729                         /* search for overlapping mappings on the same file */
730                         if (vma->vm_file->f_dentry->d_inode != file->f_dentry->d_inode)
731                                 continue;
732
733                         if (vma->vm_pgoff >= pgoff + pglen)
734                                 continue;
735
736                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
737                         vmpglen >>= PAGE_SHIFT;
738                         if (pgoff >= vma->vm_pgoff + vmpglen)
739                                 continue;
740
741                         /* handle inexactly overlapping matches between mappings */
742                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
743                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
744                                         goto sharing_violation;
745                                 continue;
746                         }
747
748                         /* we've found a VMA we can share */
749                         atomic_inc(&vma->vm_usage);
750
751                         vml->vma = vma;
752                         result = (void *) vma->vm_start;
753                         goto shared;
754                 }
755
756                 vma = NULL;
757
758                 /* obtain the address at which to make a shared mapping
759                  * - this is the hook for quasi-memory character devices to
760                  *   tell us the location of a shared mapping
761                  */
762                 if (file && file->f_op->get_unmapped_area) {
763                         addr = file->f_op->get_unmapped_area(file, addr, len,
764                                                              pgoff, flags);
765                         if (IS_ERR((void *) addr)) {
766                                 ret = addr;
767                                 if (ret != (unsigned long) -ENOSYS)
768                                         goto error;
769
770                                 /* the driver refused to tell us where to site
771                                  * the mapping so we'll have to attempt to copy
772                                  * it */
773                                 ret = (unsigned long) -ENODEV;
774                                 if (!(capabilities & BDI_CAP_MAP_COPY))
775                                         goto error;
776
777                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
778                         }
779                 }
780         }
781
782         /* we're going to need a VMA struct as well */
783         vma = kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
784         if (!vma)
785                 goto error_getting_vma;
786
787         memset(vma, 0, sizeof(*vma));
788         INIT_LIST_HEAD(&vma->anon_vma_node);
789         atomic_set(&vma->vm_usage, 1);
790         if (file)
791                 get_file(file);
792         vma->vm_file    = file;
793         vma->vm_flags   = vm_flags;
794         vma->vm_start   = addr;
795         vma->vm_end     = addr + len;
796         vma->vm_pgoff   = pgoff;
797
798         vml->vma = vma;
799
800         /* set up the mapping */
801         if (file && vma->vm_flags & VM_SHARED)
802                 ret = do_mmap_shared_file(vma, len);
803         else
804                 ret = do_mmap_private(vma, len);
805         if (ret < 0)
806                 goto error;
807
808         /* okay... we have a mapping; now we have to register it */
809         result = (void *) vma->vm_start;
810
811         if (vma->vm_flags & VM_MAPPED_COPY) {
812                 realalloc += kobjsize(result);
813                 askedalloc += len;
814         }
815
816         realalloc += kobjsize(vma);
817         askedalloc += sizeof(*vma);
818
819         current->mm->total_vm += len >> PAGE_SHIFT;
820
821         add_nommu_vma(vma);
822
823  shared:
824         realalloc += kobjsize(vml);
825         askedalloc += sizeof(*vml);
826
827         vml->next = current->mm->context.vmlist;
828         current->mm->context.vmlist = vml;
829
830         up_write(&nommu_vma_sem);
831
832         if (prot & PROT_EXEC)
833                 flush_icache_range((unsigned long) result,
834                                    (unsigned long) result + len);
835
836 #ifdef DEBUG
837         printk("do_mmap:\n");
838         show_process_blocks();
839 #endif
840
841         return (unsigned long) result;
842
843  error:
844         up_write(&nommu_vma_sem);
845         kfree(vml);
846         if (vma) {
847                 fput(vma->vm_file);
848                 kfree(vma);
849         }
850         return ret;
851
852  sharing_violation:
853         up_write(&nommu_vma_sem);
854         printk("Attempt to share mismatched mappings\n");
855         kfree(vml);
856         return -EINVAL;
857
858  error_getting_vma:
859         up_write(&nommu_vma_sem);
860         kfree(vml);
861         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
862                len, current->pid);
863         show_free_areas();
864         return -ENOMEM;
865
866  error_getting_vml:
867         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
868                len, current->pid);
869         show_free_areas();
870         return -ENOMEM;
871 }
872
873 /*
874  * handle mapping disposal for uClinux
875  */
876 static void put_vma(struct vm_area_struct *vma)
877 {
878         if (vma) {
879                 down_write(&nommu_vma_sem);
880
881                 if (atomic_dec_and_test(&vma->vm_usage)) {
882                         delete_nommu_vma(vma);
883
884                         if (vma->vm_ops && vma->vm_ops->close)
885                                 vma->vm_ops->close(vma);
886
887                         /* IO memory and memory shared directly out of the pagecache from
888                          * ramfs/tmpfs mustn't be released here */
889                         if (vma->vm_flags & VM_MAPPED_COPY) {
890                                 realalloc -= kobjsize((void *) vma->vm_start);
891                                 askedalloc -= vma->vm_end - vma->vm_start;
892                                 kfree((void *) vma->vm_start);
893                         }
894
895                         realalloc -= kobjsize(vma);
896                         askedalloc -= sizeof(*vma);
897
898                         if (vma->vm_file)
899                                 fput(vma->vm_file);
900                         kfree(vma);
901                 }
902
903                 up_write(&nommu_vma_sem);
904         }
905 }
906
907 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
908 {
909         struct vm_list_struct *vml, **parent;
910         unsigned long end = addr + len;
911
912 #ifdef DEBUG
913         printk("do_munmap:\n");
914 #endif
915
916         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next)
917                 if ((*parent)->vma->vm_start == addr &&
918                     ((len == 0) || ((*parent)->vma->vm_end == end)))
919                         goto found;
920
921         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
922                current->pid, current->comm, (void *) addr);
923         return -EINVAL;
924
925  found:
926         vml = *parent;
927
928         put_vma(vml->vma);
929
930         *parent = vml->next;
931         realalloc -= kobjsize(vml);
932         askedalloc -= sizeof(*vml);
933         kfree(vml);
934
935         update_hiwater_vm(mm);
936         mm->total_vm -= len >> PAGE_SHIFT;
937
938 #ifdef DEBUG
939         show_process_blocks();
940 #endif
941
942         return 0;
943 }
944
945 /* Release all mmaps. */
946 void exit_mmap(struct mm_struct * mm)
947 {
948         struct vm_list_struct *tmp;
949
950         if (mm) {
951 #ifdef DEBUG
952                 printk("Exit_mmap:\n");
953 #endif
954
955                 mm->total_vm = 0;
956
957                 while ((tmp = mm->context.vmlist)) {
958                         mm->context.vmlist = tmp->next;
959                         put_vma(tmp->vma);
960
961                         realalloc -= kobjsize(tmp);
962                         askedalloc -= sizeof(*tmp);
963                         kfree(tmp);
964                 }
965
966 #ifdef DEBUG
967                 show_process_blocks();
968 #endif
969         }
970 }
971
972 asmlinkage long sys_munmap(unsigned long addr, size_t len)
973 {
974         int ret;
975         struct mm_struct *mm = current->mm;
976
977         down_write(&mm->mmap_sem);
978         ret = do_munmap(mm, addr, len);
979         up_write(&mm->mmap_sem);
980         return ret;
981 }
982
983 unsigned long do_brk(unsigned long addr, unsigned long len)
984 {
985         return -ENOMEM;
986 }
987
988 /*
989  * Expand (or shrink) an existing mapping, potentially moving it at the
990  * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
991  *
992  * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
993  * This option implies MREMAP_MAYMOVE.
994  *
995  * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the
996  * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable
997  */
998 unsigned long do_mremap(unsigned long addr,
999                         unsigned long old_len, unsigned long new_len,
1000                         unsigned long flags, unsigned long new_addr)
1001 {
1002         struct vm_list_struct *vml = NULL;
1003
1004         /* insanity checks first */
1005         if (new_len == 0)
1006                 return (unsigned long) -EINVAL;
1007
1008         if (flags & MREMAP_FIXED && new_addr != addr)
1009                 return (unsigned long) -EINVAL;
1010
1011         for (vml = current->mm->context.vmlist; vml; vml = vml->next)
1012                 if (vml->vma->vm_start == addr)
1013                         goto found;
1014
1015         return (unsigned long) -EINVAL;
1016
1017  found:
1018         if (vml->vma->vm_end != vml->vma->vm_start + old_len)
1019                 return (unsigned long) -EFAULT;
1020
1021         if (vml->vma->vm_flags & VM_MAYSHARE)
1022                 return (unsigned long) -EPERM;
1023
1024         if (new_len > kobjsize((void *) addr))
1025                 return (unsigned long) -ENOMEM;
1026
1027         /* all checks complete - do it */
1028         vml->vma->vm_end = vml->vma->vm_start + new_len;
1029
1030         askedalloc -= old_len;
1031         askedalloc += new_len;
1032
1033         return vml->vma->vm_start;
1034 }
1035
1036 /*
1037  * Look up the first VMA which satisfies  addr < vm_end,  NULL if none
1038  */
1039 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1040 {
1041         struct vm_list_struct *vml;
1042
1043         for (vml = mm->context.vmlist; vml; vml = vml->next)
1044                 if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end)
1045                         return vml->vma;
1046
1047         return NULL;
1048 }
1049
1050 EXPORT_SYMBOL(find_vma);
1051
1052 struct page *follow_page(struct mm_struct *mm, unsigned long address,
1053                         unsigned int foll_flags)
1054 {
1055         return NULL;
1056 }
1057
1058 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
1059 {
1060         return NULL;
1061 }
1062
1063 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1064                 unsigned long to, unsigned long size, pgprot_t prot)
1065 {
1066         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1067         return 0;
1068 }
1069
1070 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1071 {
1072 }
1073
1074 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1075         unsigned long len, unsigned long pgoff, unsigned long flags)
1076 {
1077         return -ENOMEM;
1078 }
1079
1080 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1081 {
1082 }
1083
1084 void unmap_mapping_range(struct address_space *mapping,
1085                          loff_t const holebegin, loff_t const holelen,
1086                          int even_cows)
1087 {
1088 }
1089
1090 /*
1091  * Check that a process has enough memory to allocate a new virtual
1092  * mapping. 0 means there is enough memory for the allocation to
1093  * succeed and -ENOMEM implies there is not.
1094  *
1095  * We currently support three overcommit policies, which are set via the
1096  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1097  *
1098  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1099  * Additional code 2002 Jul 20 by Robert Love.
1100  *
1101  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1102  *
1103  * Note this is a helper function intended to be used by LSMs which
1104  * wish to use this logic.
1105  */
1106 int __vm_enough_memory(long pages, int cap_sys_admin)
1107 {
1108         unsigned long free, allowed;
1109
1110         vm_acct_memory(pages);
1111
1112         /*
1113          * Sometimes we want to use more memory than we have
1114          */
1115         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1116                 return 0;
1117
1118         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1119                 unsigned long n;
1120
1121                 free = get_page_cache_size();
1122                 free += nr_swap_pages;
1123
1124                 /*
1125                  * Any slabs which are created with the
1126                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1127                  * which are reclaimable, under pressure.  The dentry
1128                  * cache and most inode caches should fall into this
1129                  */
1130                 free += atomic_read(&slab_reclaim_pages);
1131
1132                 /*
1133                  * Leave the last 3% for root
1134                  */
1135                 if (!cap_sys_admin)
1136                         free -= free / 32;
1137
1138                 if (free > pages)
1139                         return 0;
1140
1141                 /*
1142                  * nr_free_pages() is very expensive on large systems,
1143                  * only call if we're about to fail.
1144                  */
1145                 n = nr_free_pages();
1146                 if (!cap_sys_admin)
1147                         n -= n / 32;
1148                 free += n;
1149
1150                 if (free > pages)
1151                         return 0;
1152                 vm_unacct_memory(pages);
1153                 return -ENOMEM;
1154         }
1155
1156         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1157         /*
1158          * Leave the last 3% for root
1159          */
1160         if (!cap_sys_admin)
1161                 allowed -= allowed / 32;
1162         allowed += total_swap_pages;
1163
1164         /* Don't let a single process grow too big:
1165            leave 3% of the size of this process for other processes */
1166         allowed -= current->mm->total_vm / 32;
1167
1168         /*
1169          * cast `allowed' as a signed long because vm_committed_space
1170          * sometimes has a negative value
1171          */
1172         if (atomic_read(&vm_committed_space) < (long)allowed)
1173                 return 0;
1174
1175         vm_unacct_memory(pages);
1176
1177         return -ENOMEM;
1178 }
1179
1180 int in_gate_area_no_task(unsigned long addr)
1181 {
1182         return 0;
1183 }