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