[PATCH] Check if start address is in vma region in NOMMU function get_user_pages()
[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(__vm_enough_memory);
48
49 /* list of shareable VMAs */
50 struct rb_root nommu_vma_tree = RB_ROOT;
51 DECLARE_RWSEM(nommu_vma_sem);
52
53 struct vm_operations_struct generic_file_vm_ops = {
54 };
55
56 EXPORT_SYMBOL(vfree);
57 EXPORT_SYMBOL(vmalloc_to_page);
58 EXPORT_SYMBOL(vmalloc_32);
59 EXPORT_SYMBOL(vmap);
60 EXPORT_SYMBOL(vunmap);
61
62 /*
63  * Handle all mappings that got truncated by a "truncate()"
64  * system call.
65  *
66  * NOTE! We have to be ready to update the memory sharing
67  * between the file and the memory map for a potential last
68  * incomplete page.  Ugly, but necessary.
69  */
70 int vmtruncate(struct inode *inode, loff_t offset)
71 {
72         struct address_space *mapping = inode->i_mapping;
73         unsigned long limit;
74
75         if (inode->i_size < offset)
76                 goto do_expand;
77         i_size_write(inode, offset);
78
79         truncate_inode_pages(mapping, offset);
80         goto out_truncate;
81
82 do_expand:
83         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
84         if (limit != RLIM_INFINITY && offset > limit)
85                 goto out_sig;
86         if (offset > inode->i_sb->s_maxbytes)
87                 goto out;
88         i_size_write(inode, offset);
89
90 out_truncate:
91         if (inode->i_op && inode->i_op->truncate)
92                 inode->i_op->truncate(inode);
93         return 0;
94 out_sig:
95         send_sig(SIGXFSZ, current, 0);
96 out:
97         return -EFBIG;
98 }
99
100 EXPORT_SYMBOL(vmtruncate);
101
102 /*
103  * Return the total memory allocated for this pointer, not
104  * just what the caller asked for.
105  *
106  * Doesn't have to be accurate, i.e. may have races.
107  */
108 unsigned int kobjsize(const void *objp)
109 {
110         struct page *page;
111
112         if (!objp || !((page = virt_to_page(objp))))
113                 return 0;
114
115         if (PageSlab(page))
116                 return ksize(objp);
117
118         BUG_ON(page->index < 0);
119         BUG_ON(page->index >= MAX_ORDER);
120
121         return (PAGE_SIZE << page->index);
122 }
123
124 /*
125  * The nommu dodgy version :-)
126  */
127 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
128         unsigned long start, int len, int write, int force,
129         struct page **pages, struct vm_area_struct **vmas)
130 {
131         int i;
132         struct vm_area_struct *vma;
133
134         for (i = 0; i < len; i++) {
135                 vma = find_vma(mm, start);
136                 if(!vma)
137                         return i ? : -EFAULT;
138
139                 if (pages) {
140                         pages[i] = virt_to_page(start);
141                         if (pages[i])
142                                 page_cache_get(pages[i]);
143                 }
144                 if (vmas)
145                         vmas[i] = vma;
146                 start += PAGE_SIZE;
147         }
148         return(i);
149 }
150
151 EXPORT_SYMBOL(get_user_pages);
152
153 DEFINE_RWLOCK(vmlist_lock);
154 struct vm_struct *vmlist;
155
156 void vfree(void *addr)
157 {
158         kfree(addr);
159 }
160
161 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
162 {
163         /*
164          * kmalloc doesn't like __GFP_HIGHMEM for some reason
165          */
166         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
167 }
168
169 struct page * vmalloc_to_page(void *addr)
170 {
171         return virt_to_page(addr);
172 }
173
174 unsigned long vmalloc_to_pfn(void *addr)
175 {
176         return page_to_pfn(virt_to_page(addr));
177 }
178
179
180 long vread(char *buf, char *addr, unsigned long count)
181 {
182         memcpy(buf, addr, count);
183         return count;
184 }
185
186 long vwrite(char *buf, char *addr, unsigned long count)
187 {
188         /* Don't allow overflow */
189         if ((unsigned long) addr + count < count)
190                 count = -(unsigned long) addr;
191
192         memcpy(addr, buf, count);
193         return(count);
194 }
195
196 /*
197  *      vmalloc  -  allocate virtually continguos memory
198  *
199  *      @size:          allocation size
200  *
201  *      Allocate enough pages to cover @size from the page level
202  *      allocator and map them into continguos kernel virtual space.
203  *
204  *      For tight cotrol over page level allocator and protection flags
205  *      use __vmalloc() instead.
206  */
207 void *vmalloc(unsigned long size)
208 {
209        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
210 }
211 EXPORT_SYMBOL(vmalloc);
212
213 void *vmalloc_node(unsigned long size, int node)
214 {
215         return vmalloc(size);
216 }
217 EXPORT_SYMBOL(vmalloc_node);
218
219 /*
220  *      vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
221  *
222  *      @size:          allocation size
223  *
224  *      Allocate enough 32bit PA addressable pages to cover @size from the
225  *      page level allocator and map them into continguos kernel virtual space.
226  */
227 void *vmalloc_32(unsigned long size)
228 {
229         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
230 }
231
232 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
233 {
234         BUG();
235         return NULL;
236 }
237
238 void vunmap(void *addr)
239 {
240         BUG();
241 }
242
243 /*
244  *  sys_brk() for the most part doesn't need the global kernel
245  *  lock, except when an application is doing something nasty
246  *  like trying to un-brk an area that has already been mapped
247  *  to a regular file.  in this case, the unmapping will need
248  *  to invoke file system routines that need the global lock.
249  */
250 asmlinkage unsigned long sys_brk(unsigned long brk)
251 {
252         struct mm_struct *mm = current->mm;
253
254         if (brk < mm->start_brk || brk > mm->context.end_brk)
255                 return mm->brk;
256
257         if (mm->brk == brk)
258                 return mm->brk;
259
260         /*
261          * Always allow shrinking brk
262          */
263         if (brk <= mm->brk) {
264                 mm->brk = brk;
265                 return brk;
266         }
267
268         /*
269          * Ok, looks good - let it rip.
270          */
271         return mm->brk = brk;
272 }
273
274 #ifdef DEBUG
275 static void show_process_blocks(void)
276 {
277         struct vm_list_struct *vml;
278
279         printk("Process blocks %d:", current->pid);
280
281         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
282                 printk(" %p: %p", vml, vml->vma);
283                 if (vml->vma)
284                         printk(" (%d @%lx #%d)",
285                                kobjsize((void *) vml->vma->vm_start),
286                                vml->vma->vm_start,
287                                atomic_read(&vml->vma->vm_usage));
288                 printk(vml->next ? " ->" : ".\n");
289         }
290 }
291 #endif /* DEBUG */
292
293 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
294 {
295         struct vm_area_struct *vma;
296         struct rb_node *n = nommu_vma_tree.rb_node;
297
298         while (n) {
299                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
300
301                 if (start < vma->vm_start)
302                         n = n->rb_left;
303                 else if (start > vma->vm_start)
304                         n = n->rb_right;
305                 else
306                         return vma;
307         }
308
309         return NULL;
310 }
311
312 static void add_nommu_vma(struct vm_area_struct *vma)
313 {
314         struct vm_area_struct *pvma;
315         struct address_space *mapping;
316         struct rb_node **p = &nommu_vma_tree.rb_node;
317         struct rb_node *parent = NULL;
318
319         /* add the VMA to the mapping */
320         if (vma->vm_file) {
321                 mapping = vma->vm_file->f_mapping;
322
323                 flush_dcache_mmap_lock(mapping);
324                 vma_prio_tree_insert(vma, &mapping->i_mmap);
325                 flush_dcache_mmap_unlock(mapping);
326         }
327
328         /* add the VMA to the master list */
329         while (*p) {
330                 parent = *p;
331                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
332
333                 if (vma->vm_start < pvma->vm_start) {
334                         p = &(*p)->rb_left;
335                 }
336                 else if (vma->vm_start > pvma->vm_start) {
337                         p = &(*p)->rb_right;
338                 }
339                 else {
340                         /* mappings are at the same address - this can only
341                          * happen for shared-mem chardevs and shared file
342                          * mappings backed by ramfs/tmpfs */
343                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
344
345                         if (vma < pvma)
346                                 p = &(*p)->rb_left;
347                         else if (vma > pvma)
348                                 p = &(*p)->rb_right;
349                         else
350                                 BUG();
351                 }
352         }
353
354         rb_link_node(&vma->vm_rb, parent, p);
355         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
356 }
357
358 static void delete_nommu_vma(struct vm_area_struct *vma)
359 {
360         struct address_space *mapping;
361
362         /* remove the VMA from the mapping */
363         if (vma->vm_file) {
364                 mapping = vma->vm_file->f_mapping;
365
366                 flush_dcache_mmap_lock(mapping);
367                 vma_prio_tree_remove(vma, &mapping->i_mmap);
368                 flush_dcache_mmap_unlock(mapping);
369         }
370
371         /* remove from the master list */
372         rb_erase(&vma->vm_rb, &nommu_vma_tree);
373 }
374
375 /*
376  * determine whether a mapping should be permitted and, if so, what sort of
377  * mapping we're capable of supporting
378  */
379 static int validate_mmap_request(struct file *file,
380                                  unsigned long addr,
381                                  unsigned long len,
382                                  unsigned long prot,
383                                  unsigned long flags,
384                                  unsigned long pgoff,
385                                  unsigned long *_capabilities)
386 {
387         unsigned long capabilities;
388         unsigned long reqprot = prot;
389         int ret;
390
391         /* do the simple checks first */
392         if (flags & MAP_FIXED || addr) {
393                 printk(KERN_DEBUG
394                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
395                        current->pid);
396                 return -EINVAL;
397         }
398
399         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
400             (flags & MAP_TYPE) != MAP_SHARED)
401                 return -EINVAL;
402
403         if (PAGE_ALIGN(len) == 0)
404                 return addr;
405
406         if (len > TASK_SIZE)
407                 return -EINVAL;
408
409         /* offset overflow? */
410         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
411                 return -EINVAL;
412
413         if (file) {
414                 /* validate file mapping requests */
415                 struct address_space *mapping;
416
417                 /* files must support mmap */
418                 if (!file->f_op || !file->f_op->mmap)
419                         return -ENODEV;
420
421                 /* work out if what we've got could possibly be shared
422                  * - we support chardevs that provide their own "memory"
423                  * - we support files/blockdevs that are memory backed
424                  */
425                 mapping = file->f_mapping;
426                 if (!mapping)
427                         mapping = file->f_dentry->d_inode->i_mapping;
428
429                 capabilities = 0;
430                 if (mapping && mapping->backing_dev_info)
431                         capabilities = mapping->backing_dev_info->capabilities;
432
433                 if (!capabilities) {
434                         /* no explicit capabilities set, so assume some
435                          * defaults */
436                         switch (file->f_dentry->d_inode->i_mode & S_IFMT) {
437                         case S_IFREG:
438                         case S_IFBLK:
439                                 capabilities = BDI_CAP_MAP_COPY;
440                                 break;
441
442                         case S_IFCHR:
443                                 capabilities =
444                                         BDI_CAP_MAP_DIRECT |
445                                         BDI_CAP_READ_MAP |
446                                         BDI_CAP_WRITE_MAP;
447                                 break;
448
449                         default:
450                                 return -EINVAL;
451                         }
452                 }
453
454                 /* eliminate any capabilities that we can't support on this
455                  * device */
456                 if (!file->f_op->get_unmapped_area)
457                         capabilities &= ~BDI_CAP_MAP_DIRECT;
458                 if (!file->f_op->read)
459                         capabilities &= ~BDI_CAP_MAP_COPY;
460
461                 if (flags & MAP_SHARED) {
462                         /* do checks for writing, appending and locking */
463                         if ((prot & PROT_WRITE) &&
464                             !(file->f_mode & FMODE_WRITE))
465                                 return -EACCES;
466
467                         if (IS_APPEND(file->f_dentry->d_inode) &&
468                             (file->f_mode & FMODE_WRITE))
469                                 return -EACCES;
470
471                         if (locks_verify_locked(file->f_dentry->d_inode))
472                                 return -EAGAIN;
473
474                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
475                                 return -ENODEV;
476
477                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
478                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
479                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
480                             ) {
481                                 printk("MAP_SHARED not completely supported on !MMU\n");
482                                 return -EINVAL;
483                         }
484
485                         /* we mustn't privatise shared mappings */
486                         capabilities &= ~BDI_CAP_MAP_COPY;
487                 }
488                 else {
489                         /* we're going to read the file into private memory we
490                          * allocate */
491                         if (!(capabilities & BDI_CAP_MAP_COPY))
492                                 return -ENODEV;
493
494                         /* we don't permit a private writable mapping to be
495                          * shared with the backing device */
496                         if (prot & PROT_WRITE)
497                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
498                 }
499
500                 /* handle executable mappings and implied executable
501                  * mappings */
502                 if (file->f_vfsmnt->mnt_flags & MNT_NOEXEC) {
503                         if (prot & PROT_EXEC)
504                                 return -EPERM;
505                 }
506                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
507                         /* handle implication of PROT_EXEC by PROT_READ */
508                         if (current->personality & READ_IMPLIES_EXEC) {
509                                 if (capabilities & BDI_CAP_EXEC_MAP)
510                                         prot |= PROT_EXEC;
511                         }
512                 }
513                 else if ((prot & PROT_READ) &&
514                          (prot & PROT_EXEC) &&
515                          !(capabilities & BDI_CAP_EXEC_MAP)
516                          ) {
517                         /* backing file is not executable, try to copy */
518                         capabilities &= ~BDI_CAP_MAP_DIRECT;
519                 }
520         }
521         else {
522                 /* anonymous mappings are always memory backed and can be
523                  * privately mapped
524                  */
525                 capabilities = BDI_CAP_MAP_COPY;
526
527                 /* handle PROT_EXEC implication by PROT_READ */
528                 if ((prot & PROT_READ) &&
529                     (current->personality & READ_IMPLIES_EXEC))
530                         prot |= PROT_EXEC;
531         }
532
533         /* allow the security API to have its say */
534         ret = security_file_mmap(file, reqprot, prot, flags);
535         if (ret < 0)
536                 return ret;
537
538         /* looks okay */
539         *_capabilities = capabilities;
540         return 0;
541 }
542
543 /*
544  * we've determined that we can make the mapping, now translate what we
545  * now know into VMA flags
546  */
547 static unsigned long determine_vm_flags(struct file *file,
548                                         unsigned long prot,
549                                         unsigned long flags,
550                                         unsigned long capabilities)
551 {
552         unsigned long vm_flags;
553
554         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
555         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
556         /* vm_flags |= mm->def_flags; */
557
558         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
559                 /* attempt to share read-only copies of mapped file chunks */
560                 if (file && !(prot & PROT_WRITE))
561                         vm_flags |= VM_MAYSHARE;
562         }
563         else {
564                 /* overlay a shareable mapping on the backing device or inode
565                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
566                  * romfs/cramfs */
567                 if (flags & MAP_SHARED)
568                         vm_flags |= VM_MAYSHARE | VM_SHARED;
569                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
570                         vm_flags |= VM_MAYSHARE;
571         }
572
573         /* refuse to let anyone share private mappings with this process if
574          * it's being traced - otherwise breakpoints set in it may interfere
575          * with another untraced process
576          */
577         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
578                 vm_flags &= ~VM_MAYSHARE;
579
580         return vm_flags;
581 }
582
583 /*
584  * set up a shared mapping on a file
585  */
586 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
587 {
588         int ret;
589
590         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
591         if (ret != -ENOSYS)
592                 return ret;
593
594         /* getting an ENOSYS error indicates that direct mmap isn't
595          * possible (as opposed to tried but failed) so we'll fall
596          * through to making a private copy of the data and mapping
597          * that if we can */
598         return -ENODEV;
599 }
600
601 /*
602  * set up a private mapping or an anonymous shared mapping
603  */
604 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
605 {
606         void *base;
607         int ret;
608
609         /* invoke the file's mapping function so that it can keep track of
610          * shared mappings on devices or memory
611          * - VM_MAYSHARE will be set if it may attempt to share
612          */
613         if (vma->vm_file) {
614                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
615                 if (ret != -ENOSYS) {
616                         /* shouldn't return success if we're not sharing */
617                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
618                         return ret; /* success or a real error */
619                 }
620
621                 /* getting an ENOSYS error indicates that direct mmap isn't
622                  * possible (as opposed to tried but failed) so we'll try to
623                  * make a private copy of the data and map that instead */
624         }
625
626         /* allocate some memory to hold the mapping
627          * - note that this may not return a page-aligned address if the object
628          *   we're allocating is smaller than a page
629          */
630         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
631         if (!base)
632                 goto enomem;
633
634         vma->vm_start = (unsigned long) base;
635         vma->vm_end = vma->vm_start + len;
636         vma->vm_flags |= VM_MAPPED_COPY;
637
638 #ifdef WARN_ON_SLACK
639         if (len + WARN_ON_SLACK <= kobjsize(result))
640                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
641                        len, current->pid, kobjsize(result) - len);
642 #endif
643
644         if (vma->vm_file) {
645                 /* read the contents of a file into the copy */
646                 mm_segment_t old_fs;
647                 loff_t fpos;
648
649                 fpos = vma->vm_pgoff;
650                 fpos <<= PAGE_SHIFT;
651
652                 old_fs = get_fs();
653                 set_fs(KERNEL_DS);
654                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
655                 set_fs(old_fs);
656
657                 if (ret < 0)
658                         goto error_free;
659
660                 /* clear the last little bit */
661                 if (ret < len)
662                         memset(base + ret, 0, len - ret);
663
664         } else {
665                 /* if it's an anonymous mapping, then just clear it */
666                 memset(base, 0, len);
667         }
668
669         return 0;
670
671 error_free:
672         kfree(base);
673         vma->vm_start = 0;
674         return ret;
675
676 enomem:
677         printk("Allocation of length %lu from process %d failed\n",
678                len, current->pid);
679         show_free_areas();
680         return -ENOMEM;
681 }
682
683 /*
684  * handle mapping creation for uClinux
685  */
686 unsigned long do_mmap_pgoff(struct file *file,
687                             unsigned long addr,
688                             unsigned long len,
689                             unsigned long prot,
690                             unsigned long flags,
691                             unsigned long pgoff)
692 {
693         struct vm_list_struct *vml = NULL;
694         struct vm_area_struct *vma = NULL;
695         struct rb_node *rb;
696         unsigned long capabilities, vm_flags;
697         void *result;
698         int ret;
699
700         /* decide whether we should attempt the mapping, and if so what sort of
701          * mapping */
702         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
703                                     &capabilities);
704         if (ret < 0)
705                 return ret;
706
707         /* we've determined that we can make the mapping, now translate what we
708          * now know into VMA flags */
709         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
710
711         /* we're going to need to record the mapping if it works */
712         vml = kmalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
713         if (!vml)
714                 goto error_getting_vml;
715         memset(vml, 0, sizeof(*vml));
716
717         down_write(&nommu_vma_sem);
718
719         /* if we want to share, we need to check for VMAs created by other
720          * mmap() calls that overlap with our proposed mapping
721          * - we can only share with an exact match on most regular files
722          * - shared mappings on character devices and memory backed files are
723          *   permitted to overlap inexactly as far as we are concerned for in
724          *   these cases, sharing is handled in the driver or filesystem rather
725          *   than here
726          */
727         if (vm_flags & VM_MAYSHARE) {
728                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
729                 unsigned long vmpglen;
730
731                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
732                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
733
734                         if (!(vma->vm_flags & VM_MAYSHARE))
735                                 continue;
736
737                         /* search for overlapping mappings on the same file */
738                         if (vma->vm_file->f_dentry->d_inode != file->f_dentry->d_inode)
739                                 continue;
740
741                         if (vma->vm_pgoff >= pgoff + pglen)
742                                 continue;
743
744                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
745                         vmpglen >>= PAGE_SHIFT;
746                         if (pgoff >= vma->vm_pgoff + vmpglen)
747                                 continue;
748
749                         /* handle inexactly overlapping matches between mappings */
750                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
751                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
752                                         goto sharing_violation;
753                                 continue;
754                         }
755
756                         /* we've found a VMA we can share */
757                         atomic_inc(&vma->vm_usage);
758
759                         vml->vma = vma;
760                         result = (void *) vma->vm_start;
761                         goto shared;
762                 }
763
764                 vma = NULL;
765
766                 /* obtain the address at which to make a shared mapping
767                  * - this is the hook for quasi-memory character devices to
768                  *   tell us the location of a shared mapping
769                  */
770                 if (file && file->f_op->get_unmapped_area) {
771                         addr = file->f_op->get_unmapped_area(file, addr, len,
772                                                              pgoff, flags);
773                         if (IS_ERR((void *) addr)) {
774                                 ret = addr;
775                                 if (ret != (unsigned long) -ENOSYS)
776                                         goto error;
777
778                                 /* the driver refused to tell us where to site
779                                  * the mapping so we'll have to attempt to copy
780                                  * it */
781                                 ret = (unsigned long) -ENODEV;
782                                 if (!(capabilities & BDI_CAP_MAP_COPY))
783                                         goto error;
784
785                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
786                         }
787                 }
788         }
789
790         /* we're going to need a VMA struct as well */
791         vma = kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
792         if (!vma)
793                 goto error_getting_vma;
794
795         memset(vma, 0, sizeof(*vma));
796         INIT_LIST_HEAD(&vma->anon_vma_node);
797         atomic_set(&vma->vm_usage, 1);
798         if (file)
799                 get_file(file);
800         vma->vm_file    = file;
801         vma->vm_flags   = vm_flags;
802         vma->vm_start   = addr;
803         vma->vm_end     = addr + len;
804         vma->vm_pgoff   = pgoff;
805
806         vml->vma = vma;
807
808         /* set up the mapping */
809         if (file && vma->vm_flags & VM_SHARED)
810                 ret = do_mmap_shared_file(vma, len);
811         else
812                 ret = do_mmap_private(vma, len);
813         if (ret < 0)
814                 goto error;
815
816         /* okay... we have a mapping; now we have to register it */
817         result = (void *) vma->vm_start;
818
819         if (vma->vm_flags & VM_MAPPED_COPY) {
820                 realalloc += kobjsize(result);
821                 askedalloc += len;
822         }
823
824         realalloc += kobjsize(vma);
825         askedalloc += sizeof(*vma);
826
827         current->mm->total_vm += len >> PAGE_SHIFT;
828
829         add_nommu_vma(vma);
830
831  shared:
832         realalloc += kobjsize(vml);
833         askedalloc += sizeof(*vml);
834
835         vml->next = current->mm->context.vmlist;
836         current->mm->context.vmlist = vml;
837
838         up_write(&nommu_vma_sem);
839
840         if (prot & PROT_EXEC)
841                 flush_icache_range((unsigned long) result,
842                                    (unsigned long) result + len);
843
844 #ifdef DEBUG
845         printk("do_mmap:\n");
846         show_process_blocks();
847 #endif
848
849         return (unsigned long) result;
850
851  error:
852         up_write(&nommu_vma_sem);
853         kfree(vml);
854         if (vma) {
855                 fput(vma->vm_file);
856                 kfree(vma);
857         }
858         return ret;
859
860  sharing_violation:
861         up_write(&nommu_vma_sem);
862         printk("Attempt to share mismatched mappings\n");
863         kfree(vml);
864         return -EINVAL;
865
866  error_getting_vma:
867         up_write(&nommu_vma_sem);
868         kfree(vml);
869         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
870                len, current->pid);
871         show_free_areas();
872         return -ENOMEM;
873
874  error_getting_vml:
875         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
876                len, current->pid);
877         show_free_areas();
878         return -ENOMEM;
879 }
880
881 /*
882  * handle mapping disposal for uClinux
883  */
884 static void put_vma(struct vm_area_struct *vma)
885 {
886         if (vma) {
887                 down_write(&nommu_vma_sem);
888
889                 if (atomic_dec_and_test(&vma->vm_usage)) {
890                         delete_nommu_vma(vma);
891
892                         if (vma->vm_ops && vma->vm_ops->close)
893                                 vma->vm_ops->close(vma);
894
895                         /* IO memory and memory shared directly out of the pagecache from
896                          * ramfs/tmpfs mustn't be released here */
897                         if (vma->vm_flags & VM_MAPPED_COPY) {
898                                 realalloc -= kobjsize((void *) vma->vm_start);
899                                 askedalloc -= vma->vm_end - vma->vm_start;
900                                 kfree((void *) vma->vm_start);
901                         }
902
903                         realalloc -= kobjsize(vma);
904                         askedalloc -= sizeof(*vma);
905
906                         if (vma->vm_file)
907                                 fput(vma->vm_file);
908                         kfree(vma);
909                 }
910
911                 up_write(&nommu_vma_sem);
912         }
913 }
914
915 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
916 {
917         struct vm_list_struct *vml, **parent;
918         unsigned long end = addr + len;
919
920 #ifdef DEBUG
921         printk("do_munmap:\n");
922 #endif
923
924         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next)
925                 if ((*parent)->vma->vm_start == addr &&
926                     ((len == 0) || ((*parent)->vma->vm_end == end)))
927                         goto found;
928
929         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
930                current->pid, current->comm, (void *) addr);
931         return -EINVAL;
932
933  found:
934         vml = *parent;
935
936         put_vma(vml->vma);
937
938         *parent = vml->next;
939         realalloc -= kobjsize(vml);
940         askedalloc -= sizeof(*vml);
941         kfree(vml);
942
943         update_hiwater_vm(mm);
944         mm->total_vm -= len >> PAGE_SHIFT;
945
946 #ifdef DEBUG
947         show_process_blocks();
948 #endif
949
950         return 0;
951 }
952
953 /* Release all mmaps. */
954 void exit_mmap(struct mm_struct * mm)
955 {
956         struct vm_list_struct *tmp;
957
958         if (mm) {
959 #ifdef DEBUG
960                 printk("Exit_mmap:\n");
961 #endif
962
963                 mm->total_vm = 0;
964
965                 while ((tmp = mm->context.vmlist)) {
966                         mm->context.vmlist = tmp->next;
967                         put_vma(tmp->vma);
968
969                         realalloc -= kobjsize(tmp);
970                         askedalloc -= sizeof(*tmp);
971                         kfree(tmp);
972                 }
973
974 #ifdef DEBUG
975                 show_process_blocks();
976 #endif
977         }
978 }
979
980 asmlinkage long sys_munmap(unsigned long addr, size_t len)
981 {
982         int ret;
983         struct mm_struct *mm = current->mm;
984
985         down_write(&mm->mmap_sem);
986         ret = do_munmap(mm, addr, len);
987         up_write(&mm->mmap_sem);
988         return ret;
989 }
990
991 unsigned long do_brk(unsigned long addr, unsigned long len)
992 {
993         return -ENOMEM;
994 }
995
996 /*
997  * Expand (or shrink) an existing mapping, potentially moving it at the
998  * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
999  *
1000  * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
1001  * This option implies MREMAP_MAYMOVE.
1002  *
1003  * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the
1004  * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable
1005  */
1006 unsigned long do_mremap(unsigned long addr,
1007                         unsigned long old_len, unsigned long new_len,
1008                         unsigned long flags, unsigned long new_addr)
1009 {
1010         struct vm_list_struct *vml = NULL;
1011
1012         /* insanity checks first */
1013         if (new_len == 0)
1014                 return (unsigned long) -EINVAL;
1015
1016         if (flags & MREMAP_FIXED && new_addr != addr)
1017                 return (unsigned long) -EINVAL;
1018
1019         for (vml = current->mm->context.vmlist; vml; vml = vml->next)
1020                 if (vml->vma->vm_start == addr)
1021                         goto found;
1022
1023         return (unsigned long) -EINVAL;
1024
1025  found:
1026         if (vml->vma->vm_end != vml->vma->vm_start + old_len)
1027                 return (unsigned long) -EFAULT;
1028
1029         if (vml->vma->vm_flags & VM_MAYSHARE)
1030                 return (unsigned long) -EPERM;
1031
1032         if (new_len > kobjsize((void *) addr))
1033                 return (unsigned long) -ENOMEM;
1034
1035         /* all checks complete - do it */
1036         vml->vma->vm_end = vml->vma->vm_start + new_len;
1037
1038         askedalloc -= old_len;
1039         askedalloc += new_len;
1040
1041         return vml->vma->vm_start;
1042 }
1043
1044 /*
1045  * Look up the first VMA which satisfies  addr < vm_end,  NULL if none
1046  * - should be called with mm->mmap_sem at least readlocked
1047  */
1048 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1049 {
1050         struct vm_list_struct *vml;
1051
1052         for (vml = mm->context.vmlist; vml; vml = vml->next)
1053                 if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end)
1054                         return vml->vma;
1055
1056         return NULL;
1057 }
1058
1059 EXPORT_SYMBOL(find_vma);
1060
1061 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1062                         unsigned int foll_flags)
1063 {
1064         return NULL;
1065 }
1066
1067 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
1068 {
1069         return NULL;
1070 }
1071
1072 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1073                 unsigned long to, unsigned long size, pgprot_t prot)
1074 {
1075         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1076         return 0;
1077 }
1078 EXPORT_SYMBOL(remap_pfn_range);
1079
1080 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1081 {
1082 }
1083
1084 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1085         unsigned long len, unsigned long pgoff, unsigned long flags)
1086 {
1087         return -ENOMEM;
1088 }
1089
1090 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1091 {
1092 }
1093
1094 void unmap_mapping_range(struct address_space *mapping,
1095                          loff_t const holebegin, loff_t const holelen,
1096                          int even_cows)
1097 {
1098 }
1099 EXPORT_SYMBOL(unmap_mapping_range);
1100
1101 /*
1102  * Check that a process has enough memory to allocate a new virtual
1103  * mapping. 0 means there is enough memory for the allocation to
1104  * succeed and -ENOMEM implies there is not.
1105  *
1106  * We currently support three overcommit policies, which are set via the
1107  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1108  *
1109  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1110  * Additional code 2002 Jul 20 by Robert Love.
1111  *
1112  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1113  *
1114  * Note this is a helper function intended to be used by LSMs which
1115  * wish to use this logic.
1116  */
1117 int __vm_enough_memory(long pages, int cap_sys_admin)
1118 {
1119         unsigned long free, allowed;
1120
1121         vm_acct_memory(pages);
1122
1123         /*
1124          * Sometimes we want to use more memory than we have
1125          */
1126         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1127                 return 0;
1128
1129         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1130                 unsigned long n;
1131
1132                 free = global_page_state(NR_FILE_PAGES);
1133                 free += nr_swap_pages;
1134
1135                 /*
1136                  * Any slabs which are created with the
1137                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1138                  * which are reclaimable, under pressure.  The dentry
1139                  * cache and most inode caches should fall into this
1140                  */
1141                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1142
1143                 /*
1144                  * Leave the last 3% for root
1145                  */
1146                 if (!cap_sys_admin)
1147                         free -= free / 32;
1148
1149                 if (free > pages)
1150                         return 0;
1151
1152                 /*
1153                  * nr_free_pages() is very expensive on large systems,
1154                  * only call if we're about to fail.
1155                  */
1156                 n = nr_free_pages();
1157
1158                 /*
1159                  * Leave reserved pages. The pages are not for anonymous pages.
1160                  */
1161                 if (n <= totalreserve_pages)
1162                         goto error;
1163                 else
1164                         n -= totalreserve_pages;
1165
1166                 /*
1167                  * Leave the last 3% for root
1168                  */
1169                 if (!cap_sys_admin)
1170                         n -= n / 32;
1171                 free += n;
1172
1173                 if (free > pages)
1174                         return 0;
1175
1176                 goto error;
1177         }
1178
1179         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1180         /*
1181          * Leave the last 3% for root
1182          */
1183         if (!cap_sys_admin)
1184                 allowed -= allowed / 32;
1185         allowed += total_swap_pages;
1186
1187         /* Don't let a single process grow too big:
1188            leave 3% of the size of this process for other processes */
1189         allowed -= current->mm->total_vm / 32;
1190
1191         /*
1192          * cast `allowed' as a signed long because vm_committed_space
1193          * sometimes has a negative value
1194          */
1195         if (atomic_read(&vm_committed_space) < (long)allowed)
1196                 return 0;
1197 error:
1198         vm_unacct_memory(pages);
1199
1200         return -ENOMEM;
1201 }
1202
1203 int in_gate_area_no_task(unsigned long addr)
1204 {
1205         return 0;
1206 }
1207
1208 struct page *filemap_nopage(struct vm_area_struct *area,
1209                         unsigned long address, int *type)
1210 {
1211         BUG();
1212         return NULL;
1213 }
1214
1215 /*
1216  * Access another process' address space.
1217  * - source/target buffer must be kernel space
1218  */
1219 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1220 {
1221         struct vm_area_struct *vma;
1222         struct mm_struct *mm;
1223
1224         if (addr + len < addr)
1225                 return 0;
1226
1227         mm = get_task_mm(tsk);
1228         if (!mm)
1229                 return 0;
1230
1231         down_read(&mm->mmap_sem);
1232
1233         /* the access must start within one of the target process's mappings */
1234         vma = find_vma(mm, addr);
1235         if (vma) {
1236                 /* don't overrun this mapping */
1237                 if (addr + len >= vma->vm_end)
1238                         len = vma->vm_end - addr;
1239
1240                 /* only read or write mappings where it is permitted */
1241                 if (write && vma->vm_flags & VM_WRITE)
1242                         len -= copy_to_user((void *) addr, buf, len);
1243                 else if (!write && vma->vm_flags & VM_READ)
1244                         len -= copy_from_user(buf, (void *) addr, len);
1245                 else
1246                         len = 0;
1247         } else {
1248                 len = 0;
1249         }
1250
1251         up_read(&mm->mmap_sem);
1252         mmput(mm);
1253         return len;
1254 }