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