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