Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux...
[pv_ops_mirror.git] / mm / nommu.c
blob5d8ae086f74e541a6e526288e072e87b665484ab
1 /*
2 * linux/mm/nommu.c
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).
7 * See Documentation/nommu-mmap.txt
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 * Copyright (c) 2007 Paul Mundt <lethal@linux-sh.org>
16 #include <linux/module.h>
17 #include <linux/mm.h>
18 #include <linux/mman.h>
19 #include <linux/swap.h>
20 #include <linux/file.h>
21 #include <linux/highmem.h>
22 #include <linux/pagemap.h>
23 #include <linux/slab.h>
24 #include <linux/vmalloc.h>
25 #include <linux/ptrace.h>
26 #include <linux/blkdev.h>
27 #include <linux/backing-dev.h>
28 #include <linux/mount.h>
29 #include <linux/personality.h>
30 #include <linux/security.h>
31 #include <linux/syscalls.h>
33 #include <asm/uaccess.h>
34 #include <asm/tlb.h>
35 #include <asm/tlbflush.h>
37 void *high_memory;
38 struct page *mem_map;
39 unsigned long max_mapnr;
40 unsigned long num_physpages;
41 unsigned long askedalloc, realalloc;
42 atomic_t vm_committed_space = ATOMIC_INIT(0);
43 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
44 int sysctl_overcommit_ratio = 50; /* default is 50% */
45 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
46 int heap_stack_gap = 0;
48 EXPORT_SYMBOL(mem_map);
49 EXPORT_SYMBOL(num_physpages);
51 /* list of shareable VMAs */
52 struct rb_root nommu_vma_tree = RB_ROOT;
53 DECLARE_RWSEM(nommu_vma_sem);
55 struct vm_operations_struct generic_file_vm_ops = {
59 * Handle all mappings that got truncated by a "truncate()"
60 * system call.
62 * NOTE! We have to be ready to update the memory sharing
63 * between the file and the memory map for a potential last
64 * incomplete page. Ugly, but necessary.
66 int vmtruncate(struct inode *inode, loff_t offset)
68 struct address_space *mapping = inode->i_mapping;
69 unsigned long limit;
71 if (inode->i_size < offset)
72 goto do_expand;
73 i_size_write(inode, offset);
75 truncate_inode_pages(mapping, offset);
76 goto out_truncate;
78 do_expand:
79 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
80 if (limit != RLIM_INFINITY && offset > limit)
81 goto out_sig;
82 if (offset > inode->i_sb->s_maxbytes)
83 goto out;
84 i_size_write(inode, offset);
86 out_truncate:
87 if (inode->i_op && inode->i_op->truncate)
88 inode->i_op->truncate(inode);
89 return 0;
90 out_sig:
91 send_sig(SIGXFSZ, current, 0);
92 out:
93 return -EFBIG;
96 EXPORT_SYMBOL(vmtruncate);
99 * Return the total memory allocated for this pointer, not
100 * just what the caller asked for.
102 * Doesn't have to be accurate, i.e. may have races.
104 unsigned int kobjsize(const void *objp)
106 struct page *page;
108 if (!objp || !((page = virt_to_page(objp))))
109 return 0;
111 if (PageSlab(page))
112 return ksize(objp);
114 BUG_ON(page->index < 0);
115 BUG_ON(page->index >= MAX_ORDER);
117 return (PAGE_SIZE << page->index);
121 * get a list of pages in an address range belonging to the specified process
122 * and indicate the VMA that covers each page
123 * - this is potentially dodgy as we may end incrementing the page count of a
124 * slab page or a secondary page from a compound page
125 * - don't permit access to VMAs that don't support it, such as I/O mappings
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)
131 struct vm_area_struct *vma;
132 unsigned long vm_flags;
133 int i;
135 /* calculate required read or write permissions.
136 * - if 'force' is set, we only require the "MAY" flags.
138 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
139 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
141 for (i = 0; i < len; i++) {
142 vma = find_vma(mm, start);
143 if (!vma)
144 goto finish_or_fault;
146 /* protect what we can, including chardevs */
147 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
148 !(vm_flags & vma->vm_flags))
149 goto finish_or_fault;
151 if (pages) {
152 pages[i] = virt_to_page(start);
153 if (pages[i])
154 page_cache_get(pages[i]);
156 if (vmas)
157 vmas[i] = vma;
158 start += PAGE_SIZE;
161 return i;
163 finish_or_fault:
164 return i ? : -EFAULT;
166 EXPORT_SYMBOL(get_user_pages);
168 DEFINE_RWLOCK(vmlist_lock);
169 struct vm_struct *vmlist;
171 void vfree(const void *addr)
173 kfree(addr);
175 EXPORT_SYMBOL(vfree);
177 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
180 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
181 * returns only a logical address.
183 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
185 EXPORT_SYMBOL(__vmalloc);
187 void *vmalloc_user(unsigned long size)
189 void *ret;
191 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
192 PAGE_KERNEL);
193 if (ret) {
194 struct vm_area_struct *vma;
196 down_write(&current->mm->mmap_sem);
197 vma = find_vma(current->mm, (unsigned long)ret);
198 if (vma)
199 vma->vm_flags |= VM_USERMAP;
200 up_write(&current->mm->mmap_sem);
203 return ret;
205 EXPORT_SYMBOL(vmalloc_user);
207 struct page *vmalloc_to_page(const void *addr)
209 return virt_to_page(addr);
211 EXPORT_SYMBOL(vmalloc_to_page);
213 unsigned long vmalloc_to_pfn(const void *addr)
215 return page_to_pfn(virt_to_page(addr));
217 EXPORT_SYMBOL(vmalloc_to_pfn);
219 long vread(char *buf, char *addr, unsigned long count)
221 memcpy(buf, addr, count);
222 return count;
225 long vwrite(char *buf, char *addr, unsigned long count)
227 /* Don't allow overflow */
228 if ((unsigned long) addr + count < count)
229 count = -(unsigned long) addr;
231 memcpy(addr, buf, count);
232 return(count);
236 * vmalloc - allocate virtually continguos memory
238 * @size: allocation size
240 * Allocate enough pages to cover @size from the page level
241 * allocator and map them into continguos kernel virtual space.
243 * For tight control over page level allocator and protection flags
244 * use __vmalloc() instead.
246 void *vmalloc(unsigned long size)
248 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
250 EXPORT_SYMBOL(vmalloc);
252 void *vmalloc_node(unsigned long size, int node)
254 return vmalloc(size);
256 EXPORT_SYMBOL(vmalloc_node);
259 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable)
260 * @size: allocation size
262 * Allocate enough 32bit PA addressable pages to cover @size from the
263 * page level allocator and map them into continguos kernel virtual space.
265 void *vmalloc_32(unsigned long size)
267 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
269 EXPORT_SYMBOL(vmalloc_32);
272 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
273 * @size: allocation size
275 * The resulting memory area is 32bit addressable and zeroed so it can be
276 * mapped to userspace without leaking data.
278 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
279 * remap_vmalloc_range() are permissible.
281 void *vmalloc_32_user(unsigned long size)
284 * We'll have to sort out the ZONE_DMA bits for 64-bit,
285 * but for now this can simply use vmalloc_user() directly.
287 return vmalloc_user(size);
289 EXPORT_SYMBOL(vmalloc_32_user);
291 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
293 BUG();
294 return NULL;
296 EXPORT_SYMBOL(vmap);
298 void vunmap(const void *addr)
300 BUG();
302 EXPORT_SYMBOL(vunmap);
305 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
306 * have one.
308 void __attribute__((weak)) vmalloc_sync_all(void)
312 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
313 struct page *page)
315 return -EINVAL;
317 EXPORT_SYMBOL(vm_insert_page);
320 * sys_brk() for the most part doesn't need the global kernel
321 * lock, except when an application is doing something nasty
322 * like trying to un-brk an area that has already been mapped
323 * to a regular file. in this case, the unmapping will need
324 * to invoke file system routines that need the global lock.
326 asmlinkage unsigned long sys_brk(unsigned long brk)
328 struct mm_struct *mm = current->mm;
330 if (brk < mm->start_brk || brk > mm->context.end_brk)
331 return mm->brk;
333 if (mm->brk == brk)
334 return mm->brk;
337 * Always allow shrinking brk
339 if (brk <= mm->brk) {
340 mm->brk = brk;
341 return brk;
345 * Ok, looks good - let it rip.
347 return mm->brk = brk;
350 #ifdef DEBUG
351 static void show_process_blocks(void)
353 struct vm_list_struct *vml;
355 printk("Process blocks %d:", current->pid);
357 for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
358 printk(" %p: %p", vml, vml->vma);
359 if (vml->vma)
360 printk(" (%d @%lx #%d)",
361 kobjsize((void *) vml->vma->vm_start),
362 vml->vma->vm_start,
363 atomic_read(&vml->vma->vm_usage));
364 printk(vml->next ? " ->" : ".\n");
367 #endif /* DEBUG */
370 * add a VMA into a process's mm_struct in the appropriate place in the list
371 * - should be called with mm->mmap_sem held writelocked
373 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
375 struct vm_list_struct **ppv;
377 for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
378 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
379 break;
381 vml->next = *ppv;
382 *ppv = vml;
386 * look up the first VMA in which addr resides, NULL if none
387 * - should be called with mm->mmap_sem at least held readlocked
389 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
391 struct vm_list_struct *loop, *vml;
393 /* search the vm_start ordered list */
394 vml = NULL;
395 for (loop = mm->context.vmlist; loop; loop = loop->next) {
396 if (loop->vma->vm_start > addr)
397 break;
398 vml = loop;
401 if (vml && vml->vma->vm_end > addr)
402 return vml->vma;
404 return NULL;
406 EXPORT_SYMBOL(find_vma);
409 * find a VMA
410 * - we don't extend stack VMAs under NOMMU conditions
412 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
414 return find_vma(mm, addr);
417 int expand_stack(struct vm_area_struct *vma, unsigned long address)
419 return -ENOMEM;
423 * look up the first VMA exactly that exactly matches addr
424 * - should be called with mm->mmap_sem at least held readlocked
426 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
427 unsigned long addr)
429 struct vm_list_struct *vml;
431 /* search the vm_start ordered list */
432 for (vml = mm->context.vmlist; vml; vml = vml->next) {
433 if (vml->vma->vm_start == addr)
434 return vml->vma;
435 if (vml->vma->vm_start > addr)
436 break;
439 return NULL;
443 * find a VMA in the global tree
445 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
447 struct vm_area_struct *vma;
448 struct rb_node *n = nommu_vma_tree.rb_node;
450 while (n) {
451 vma = rb_entry(n, struct vm_area_struct, vm_rb);
453 if (start < vma->vm_start)
454 n = n->rb_left;
455 else if (start > vma->vm_start)
456 n = n->rb_right;
457 else
458 return vma;
461 return NULL;
465 * add a VMA in the global tree
467 static void add_nommu_vma(struct vm_area_struct *vma)
469 struct vm_area_struct *pvma;
470 struct address_space *mapping;
471 struct rb_node **p = &nommu_vma_tree.rb_node;
472 struct rb_node *parent = NULL;
474 /* add the VMA to the mapping */
475 if (vma->vm_file) {
476 mapping = vma->vm_file->f_mapping;
478 flush_dcache_mmap_lock(mapping);
479 vma_prio_tree_insert(vma, &mapping->i_mmap);
480 flush_dcache_mmap_unlock(mapping);
483 /* add the VMA to the master list */
484 while (*p) {
485 parent = *p;
486 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
488 if (vma->vm_start < pvma->vm_start) {
489 p = &(*p)->rb_left;
491 else if (vma->vm_start > pvma->vm_start) {
492 p = &(*p)->rb_right;
494 else {
495 /* mappings are at the same address - this can only
496 * happen for shared-mem chardevs and shared file
497 * mappings backed by ramfs/tmpfs */
498 BUG_ON(!(pvma->vm_flags & VM_SHARED));
500 if (vma < pvma)
501 p = &(*p)->rb_left;
502 else if (vma > pvma)
503 p = &(*p)->rb_right;
504 else
505 BUG();
509 rb_link_node(&vma->vm_rb, parent, p);
510 rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
514 * delete a VMA from the global list
516 static void delete_nommu_vma(struct vm_area_struct *vma)
518 struct address_space *mapping;
520 /* remove the VMA from the mapping */
521 if (vma->vm_file) {
522 mapping = vma->vm_file->f_mapping;
524 flush_dcache_mmap_lock(mapping);
525 vma_prio_tree_remove(vma, &mapping->i_mmap);
526 flush_dcache_mmap_unlock(mapping);
529 /* remove from the master list */
530 rb_erase(&vma->vm_rb, &nommu_vma_tree);
534 * determine whether a mapping should be permitted and, if so, what sort of
535 * mapping we're capable of supporting
537 static int validate_mmap_request(struct file *file,
538 unsigned long addr,
539 unsigned long len,
540 unsigned long prot,
541 unsigned long flags,
542 unsigned long pgoff,
543 unsigned long *_capabilities)
545 unsigned long capabilities;
546 unsigned long reqprot = prot;
547 int ret;
549 /* do the simple checks first */
550 if (flags & MAP_FIXED || addr) {
551 printk(KERN_DEBUG
552 "%d: Can't do fixed-address/overlay mmap of RAM\n",
553 current->pid);
554 return -EINVAL;
557 if ((flags & MAP_TYPE) != MAP_PRIVATE &&
558 (flags & MAP_TYPE) != MAP_SHARED)
559 return -EINVAL;
561 if (!len)
562 return -EINVAL;
564 /* Careful about overflows.. */
565 len = PAGE_ALIGN(len);
566 if (!len || len > TASK_SIZE)
567 return -ENOMEM;
569 /* offset overflow? */
570 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
571 return -EOVERFLOW;
573 if (file) {
574 /* validate file mapping requests */
575 struct address_space *mapping;
577 /* files must support mmap */
578 if (!file->f_op || !file->f_op->mmap)
579 return -ENODEV;
581 /* work out if what we've got could possibly be shared
582 * - we support chardevs that provide their own "memory"
583 * - we support files/blockdevs that are memory backed
585 mapping = file->f_mapping;
586 if (!mapping)
587 mapping = file->f_path.dentry->d_inode->i_mapping;
589 capabilities = 0;
590 if (mapping && mapping->backing_dev_info)
591 capabilities = mapping->backing_dev_info->capabilities;
593 if (!capabilities) {
594 /* no explicit capabilities set, so assume some
595 * defaults */
596 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
597 case S_IFREG:
598 case S_IFBLK:
599 capabilities = BDI_CAP_MAP_COPY;
600 break;
602 case S_IFCHR:
603 capabilities =
604 BDI_CAP_MAP_DIRECT |
605 BDI_CAP_READ_MAP |
606 BDI_CAP_WRITE_MAP;
607 break;
609 default:
610 return -EINVAL;
614 /* eliminate any capabilities that we can't support on this
615 * device */
616 if (!file->f_op->get_unmapped_area)
617 capabilities &= ~BDI_CAP_MAP_DIRECT;
618 if (!file->f_op->read)
619 capabilities &= ~BDI_CAP_MAP_COPY;
621 if (flags & MAP_SHARED) {
622 /* do checks for writing, appending and locking */
623 if ((prot & PROT_WRITE) &&
624 !(file->f_mode & FMODE_WRITE))
625 return -EACCES;
627 if (IS_APPEND(file->f_path.dentry->d_inode) &&
628 (file->f_mode & FMODE_WRITE))
629 return -EACCES;
631 if (locks_verify_locked(file->f_path.dentry->d_inode))
632 return -EAGAIN;
634 if (!(capabilities & BDI_CAP_MAP_DIRECT))
635 return -ENODEV;
637 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) ||
638 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
639 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP))
641 printk("MAP_SHARED not completely supported on !MMU\n");
642 return -EINVAL;
645 /* we mustn't privatise shared mappings */
646 capabilities &= ~BDI_CAP_MAP_COPY;
648 else {
649 /* we're going to read the file into private memory we
650 * allocate */
651 if (!(capabilities & BDI_CAP_MAP_COPY))
652 return -ENODEV;
654 /* we don't permit a private writable mapping to be
655 * shared with the backing device */
656 if (prot & PROT_WRITE)
657 capabilities &= ~BDI_CAP_MAP_DIRECT;
660 /* handle executable mappings and implied executable
661 * mappings */
662 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
663 if (prot & PROT_EXEC)
664 return -EPERM;
666 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
667 /* handle implication of PROT_EXEC by PROT_READ */
668 if (current->personality & READ_IMPLIES_EXEC) {
669 if (capabilities & BDI_CAP_EXEC_MAP)
670 prot |= PROT_EXEC;
673 else if ((prot & PROT_READ) &&
674 (prot & PROT_EXEC) &&
675 !(capabilities & BDI_CAP_EXEC_MAP)
677 /* backing file is not executable, try to copy */
678 capabilities &= ~BDI_CAP_MAP_DIRECT;
681 else {
682 /* anonymous mappings are always memory backed and can be
683 * privately mapped
685 capabilities = BDI_CAP_MAP_COPY;
687 /* handle PROT_EXEC implication by PROT_READ */
688 if ((prot & PROT_READ) &&
689 (current->personality & READ_IMPLIES_EXEC))
690 prot |= PROT_EXEC;
693 /* allow the security API to have its say */
694 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
695 if (ret < 0)
696 return ret;
698 /* looks okay */
699 *_capabilities = capabilities;
700 return 0;
704 * we've determined that we can make the mapping, now translate what we
705 * now know into VMA flags
707 static unsigned long determine_vm_flags(struct file *file,
708 unsigned long prot,
709 unsigned long flags,
710 unsigned long capabilities)
712 unsigned long vm_flags;
714 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
715 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
716 /* vm_flags |= mm->def_flags; */
718 if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
719 /* attempt to share read-only copies of mapped file chunks */
720 if (file && !(prot & PROT_WRITE))
721 vm_flags |= VM_MAYSHARE;
723 else {
724 /* overlay a shareable mapping on the backing device or inode
725 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
726 * romfs/cramfs */
727 if (flags & MAP_SHARED)
728 vm_flags |= VM_MAYSHARE | VM_SHARED;
729 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
730 vm_flags |= VM_MAYSHARE;
733 /* refuse to let anyone share private mappings with this process if
734 * it's being traced - otherwise breakpoints set in it may interfere
735 * with another untraced process
737 if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
738 vm_flags &= ~VM_MAYSHARE;
740 return vm_flags;
744 * set up a shared mapping on a file
746 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
748 int ret;
750 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
751 if (ret != -ENOSYS)
752 return ret;
754 /* getting an ENOSYS error indicates that direct mmap isn't
755 * possible (as opposed to tried but failed) so we'll fall
756 * through to making a private copy of the data and mapping
757 * that if we can */
758 return -ENODEV;
762 * set up a private mapping or an anonymous shared mapping
764 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
766 void *base;
767 int ret;
769 /* invoke the file's mapping function so that it can keep track of
770 * shared mappings on devices or memory
771 * - VM_MAYSHARE will be set if it may attempt to share
773 if (vma->vm_file) {
774 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
775 if (ret != -ENOSYS) {
776 /* shouldn't return success if we're not sharing */
777 BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
778 return ret; /* success or a real error */
781 /* getting an ENOSYS error indicates that direct mmap isn't
782 * possible (as opposed to tried but failed) so we'll try to
783 * make a private copy of the data and map that instead */
786 /* allocate some memory to hold the mapping
787 * - note that this may not return a page-aligned address if the object
788 * we're allocating is smaller than a page
790 base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
791 if (!base)
792 goto enomem;
794 vma->vm_start = (unsigned long) base;
795 vma->vm_end = vma->vm_start + len;
796 vma->vm_flags |= VM_MAPPED_COPY;
798 #ifdef WARN_ON_SLACK
799 if (len + WARN_ON_SLACK <= kobjsize(result))
800 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
801 len, current->pid, kobjsize(result) - len);
802 #endif
804 if (vma->vm_file) {
805 /* read the contents of a file into the copy */
806 mm_segment_t old_fs;
807 loff_t fpos;
809 fpos = vma->vm_pgoff;
810 fpos <<= PAGE_SHIFT;
812 old_fs = get_fs();
813 set_fs(KERNEL_DS);
814 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
815 set_fs(old_fs);
817 if (ret < 0)
818 goto error_free;
820 /* clear the last little bit */
821 if (ret < len)
822 memset(base + ret, 0, len - ret);
824 } else {
825 /* if it's an anonymous mapping, then just clear it */
826 memset(base, 0, len);
829 return 0;
831 error_free:
832 kfree(base);
833 vma->vm_start = 0;
834 return ret;
836 enomem:
837 printk("Allocation of length %lu from process %d failed\n",
838 len, current->pid);
839 show_free_areas();
840 return -ENOMEM;
844 * handle mapping creation for uClinux
846 unsigned long do_mmap_pgoff(struct file *file,
847 unsigned long addr,
848 unsigned long len,
849 unsigned long prot,
850 unsigned long flags,
851 unsigned long pgoff)
853 struct vm_list_struct *vml = NULL;
854 struct vm_area_struct *vma = NULL;
855 struct rb_node *rb;
856 unsigned long capabilities, vm_flags;
857 void *result;
858 int ret;
860 if (!(flags & MAP_FIXED))
861 addr = round_hint_to_min(addr);
863 /* decide whether we should attempt the mapping, and if so what sort of
864 * mapping */
865 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
866 &capabilities);
867 if (ret < 0)
868 return ret;
870 /* we've determined that we can make the mapping, now translate what we
871 * now know into VMA flags */
872 vm_flags = determine_vm_flags(file, prot, flags, capabilities);
874 /* we're going to need to record the mapping if it works */
875 vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
876 if (!vml)
877 goto error_getting_vml;
879 down_write(&nommu_vma_sem);
881 /* if we want to share, we need to check for VMAs created by other
882 * mmap() calls that overlap with our proposed mapping
883 * - we can only share with an exact match on most regular files
884 * - shared mappings on character devices and memory backed files are
885 * permitted to overlap inexactly as far as we are concerned for in
886 * these cases, sharing is handled in the driver or filesystem rather
887 * than here
889 if (vm_flags & VM_MAYSHARE) {
890 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
891 unsigned long vmpglen;
893 /* suppress VMA sharing for shared regions */
894 if (vm_flags & VM_SHARED &&
895 capabilities & BDI_CAP_MAP_DIRECT)
896 goto dont_share_VMAs;
898 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
899 vma = rb_entry(rb, struct vm_area_struct, vm_rb);
901 if (!(vma->vm_flags & VM_MAYSHARE))
902 continue;
904 /* search for overlapping mappings on the same file */
905 if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
906 continue;
908 if (vma->vm_pgoff >= pgoff + pglen)
909 continue;
911 vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
912 vmpglen >>= PAGE_SHIFT;
913 if (pgoff >= vma->vm_pgoff + vmpglen)
914 continue;
916 /* handle inexactly overlapping matches between mappings */
917 if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
918 if (!(capabilities & BDI_CAP_MAP_DIRECT))
919 goto sharing_violation;
920 continue;
923 /* we've found a VMA we can share */
924 atomic_inc(&vma->vm_usage);
926 vml->vma = vma;
927 result = (void *) vma->vm_start;
928 goto shared;
931 dont_share_VMAs:
932 vma = NULL;
934 /* obtain the address at which to make a shared mapping
935 * - this is the hook for quasi-memory character devices to
936 * tell us the location of a shared mapping
938 if (file && file->f_op->get_unmapped_area) {
939 addr = file->f_op->get_unmapped_area(file, addr, len,
940 pgoff, flags);
941 if (IS_ERR((void *) addr)) {
942 ret = addr;
943 if (ret != (unsigned long) -ENOSYS)
944 goto error;
946 /* the driver refused to tell us where to site
947 * the mapping so we'll have to attempt to copy
948 * it */
949 ret = (unsigned long) -ENODEV;
950 if (!(capabilities & BDI_CAP_MAP_COPY))
951 goto error;
953 capabilities &= ~BDI_CAP_MAP_DIRECT;
958 /* we're going to need a VMA struct as well */
959 vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
960 if (!vma)
961 goto error_getting_vma;
963 INIT_LIST_HEAD(&vma->anon_vma_node);
964 atomic_set(&vma->vm_usage, 1);
965 if (file)
966 get_file(file);
967 vma->vm_file = file;
968 vma->vm_flags = vm_flags;
969 vma->vm_start = addr;
970 vma->vm_end = addr + len;
971 vma->vm_pgoff = pgoff;
973 vml->vma = vma;
975 /* set up the mapping */
976 if (file && vma->vm_flags & VM_SHARED)
977 ret = do_mmap_shared_file(vma, len);
978 else
979 ret = do_mmap_private(vma, len);
980 if (ret < 0)
981 goto error;
983 /* okay... we have a mapping; now we have to register it */
984 result = (void *) vma->vm_start;
986 if (vma->vm_flags & VM_MAPPED_COPY) {
987 realalloc += kobjsize(result);
988 askedalloc += len;
991 realalloc += kobjsize(vma);
992 askedalloc += sizeof(*vma);
994 current->mm->total_vm += len >> PAGE_SHIFT;
996 add_nommu_vma(vma);
998 shared:
999 realalloc += kobjsize(vml);
1000 askedalloc += sizeof(*vml);
1002 add_vma_to_mm(current->mm, vml);
1004 up_write(&nommu_vma_sem);
1006 if (prot & PROT_EXEC)
1007 flush_icache_range((unsigned long) result,
1008 (unsigned long) result + len);
1010 #ifdef DEBUG
1011 printk("do_mmap:\n");
1012 show_process_blocks();
1013 #endif
1015 return (unsigned long) result;
1017 error:
1018 up_write(&nommu_vma_sem);
1019 kfree(vml);
1020 if (vma) {
1021 if (vma->vm_file)
1022 fput(vma->vm_file);
1023 kfree(vma);
1025 return ret;
1027 sharing_violation:
1028 up_write(&nommu_vma_sem);
1029 printk("Attempt to share mismatched mappings\n");
1030 kfree(vml);
1031 return -EINVAL;
1033 error_getting_vma:
1034 up_write(&nommu_vma_sem);
1035 kfree(vml);
1036 printk("Allocation of vma for %lu byte allocation from process %d failed\n",
1037 len, current->pid);
1038 show_free_areas();
1039 return -ENOMEM;
1041 error_getting_vml:
1042 printk("Allocation of vml for %lu byte allocation from process %d failed\n",
1043 len, current->pid);
1044 show_free_areas();
1045 return -ENOMEM;
1047 EXPORT_SYMBOL(do_mmap_pgoff);
1050 * handle mapping disposal for uClinux
1052 static void put_vma(struct vm_area_struct *vma)
1054 if (vma) {
1055 down_write(&nommu_vma_sem);
1057 if (atomic_dec_and_test(&vma->vm_usage)) {
1058 delete_nommu_vma(vma);
1060 if (vma->vm_ops && vma->vm_ops->close)
1061 vma->vm_ops->close(vma);
1063 /* IO memory and memory shared directly out of the pagecache from
1064 * ramfs/tmpfs mustn't be released here */
1065 if (vma->vm_flags & VM_MAPPED_COPY) {
1066 realalloc -= kobjsize((void *) vma->vm_start);
1067 askedalloc -= vma->vm_end - vma->vm_start;
1068 kfree((void *) vma->vm_start);
1071 realalloc -= kobjsize(vma);
1072 askedalloc -= sizeof(*vma);
1074 if (vma->vm_file)
1075 fput(vma->vm_file);
1076 kfree(vma);
1079 up_write(&nommu_vma_sem);
1084 * release a mapping
1085 * - under NOMMU conditions the parameters must match exactly to the mapping to
1086 * be removed
1088 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1090 struct vm_list_struct *vml, **parent;
1091 unsigned long end = addr + len;
1093 #ifdef DEBUG
1094 printk("do_munmap:\n");
1095 #endif
1097 for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1098 if ((*parent)->vma->vm_start > addr)
1099 break;
1100 if ((*parent)->vma->vm_start == addr &&
1101 ((len == 0) || ((*parent)->vma->vm_end == end)))
1102 goto found;
1105 printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1106 current->pid, current->comm, (void *) addr);
1107 return -EINVAL;
1109 found:
1110 vml = *parent;
1112 put_vma(vml->vma);
1114 *parent = vml->next;
1115 realalloc -= kobjsize(vml);
1116 askedalloc -= sizeof(*vml);
1117 kfree(vml);
1119 update_hiwater_vm(mm);
1120 mm->total_vm -= len >> PAGE_SHIFT;
1122 #ifdef DEBUG
1123 show_process_blocks();
1124 #endif
1126 return 0;
1128 EXPORT_SYMBOL(do_munmap);
1130 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1132 int ret;
1133 struct mm_struct *mm = current->mm;
1135 down_write(&mm->mmap_sem);
1136 ret = do_munmap(mm, addr, len);
1137 up_write(&mm->mmap_sem);
1138 return ret;
1142 * Release all mappings
1144 void exit_mmap(struct mm_struct * mm)
1146 struct vm_list_struct *tmp;
1148 if (mm) {
1149 #ifdef DEBUG
1150 printk("Exit_mmap:\n");
1151 #endif
1153 mm->total_vm = 0;
1155 while ((tmp = mm->context.vmlist)) {
1156 mm->context.vmlist = tmp->next;
1157 put_vma(tmp->vma);
1159 realalloc -= kobjsize(tmp);
1160 askedalloc -= sizeof(*tmp);
1161 kfree(tmp);
1164 #ifdef DEBUG
1165 show_process_blocks();
1166 #endif
1170 unsigned long do_brk(unsigned long addr, unsigned long len)
1172 return -ENOMEM;
1176 * expand (or shrink) an existing mapping, potentially moving it at the same
1177 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1179 * under NOMMU conditions, we only permit changing a mapping's size, and only
1180 * as long as it stays within the hole allocated by the kmalloc() call in
1181 * do_mmap_pgoff() and the block is not shareable
1183 * MREMAP_FIXED is not supported under NOMMU conditions
1185 unsigned long do_mremap(unsigned long addr,
1186 unsigned long old_len, unsigned long new_len,
1187 unsigned long flags, unsigned long new_addr)
1189 struct vm_area_struct *vma;
1191 /* insanity checks first */
1192 if (new_len == 0)
1193 return (unsigned long) -EINVAL;
1195 if (flags & MREMAP_FIXED && new_addr != addr)
1196 return (unsigned long) -EINVAL;
1198 vma = find_vma_exact(current->mm, addr);
1199 if (!vma)
1200 return (unsigned long) -EINVAL;
1202 if (vma->vm_end != vma->vm_start + old_len)
1203 return (unsigned long) -EFAULT;
1205 if (vma->vm_flags & VM_MAYSHARE)
1206 return (unsigned long) -EPERM;
1208 if (new_len > kobjsize((void *) addr))
1209 return (unsigned long) -ENOMEM;
1211 /* all checks complete - do it */
1212 vma->vm_end = vma->vm_start + new_len;
1214 askedalloc -= old_len;
1215 askedalloc += new_len;
1217 return vma->vm_start;
1219 EXPORT_SYMBOL(do_mremap);
1221 asmlinkage unsigned long sys_mremap(unsigned long addr,
1222 unsigned long old_len, unsigned long new_len,
1223 unsigned long flags, unsigned long new_addr)
1225 unsigned long ret;
1227 down_write(&current->mm->mmap_sem);
1228 ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1229 up_write(&current->mm->mmap_sem);
1230 return ret;
1233 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1234 unsigned int foll_flags)
1236 return NULL;
1239 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1240 unsigned long to, unsigned long size, pgprot_t prot)
1242 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1243 return 0;
1245 EXPORT_SYMBOL(remap_pfn_range);
1247 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1248 unsigned long pgoff)
1250 unsigned int size = vma->vm_end - vma->vm_start;
1252 if (!(vma->vm_flags & VM_USERMAP))
1253 return -EINVAL;
1255 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1256 vma->vm_end = vma->vm_start + size;
1258 return 0;
1260 EXPORT_SYMBOL(remap_vmalloc_range);
1262 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1266 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1267 unsigned long len, unsigned long pgoff, unsigned long flags)
1269 return -ENOMEM;
1272 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1276 void unmap_mapping_range(struct address_space *mapping,
1277 loff_t const holebegin, loff_t const holelen,
1278 int even_cows)
1281 EXPORT_SYMBOL(unmap_mapping_range);
1284 * ask for an unmapped area at which to create a mapping on a file
1286 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1287 unsigned long len, unsigned long pgoff,
1288 unsigned long flags)
1290 unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1291 unsigned long, unsigned long);
1293 get_area = current->mm->get_unmapped_area;
1294 if (file && file->f_op && file->f_op->get_unmapped_area)
1295 get_area = file->f_op->get_unmapped_area;
1297 if (!get_area)
1298 return -ENOSYS;
1300 return get_area(file, addr, len, pgoff, flags);
1302 EXPORT_SYMBOL(get_unmapped_area);
1305 * Check that a process has enough memory to allocate a new virtual
1306 * mapping. 0 means there is enough memory for the allocation to
1307 * succeed and -ENOMEM implies there is not.
1309 * We currently support three overcommit policies, which are set via the
1310 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting
1312 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1313 * Additional code 2002 Jul 20 by Robert Love.
1315 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1317 * Note this is a helper function intended to be used by LSMs which
1318 * wish to use this logic.
1320 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1322 unsigned long free, allowed;
1324 vm_acct_memory(pages);
1327 * Sometimes we want to use more memory than we have
1329 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1330 return 0;
1332 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1333 unsigned long n;
1335 free = global_page_state(NR_FILE_PAGES);
1336 free += nr_swap_pages;
1339 * Any slabs which are created with the
1340 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1341 * which are reclaimable, under pressure. The dentry
1342 * cache and most inode caches should fall into this
1344 free += global_page_state(NR_SLAB_RECLAIMABLE);
1347 * Leave the last 3% for root
1349 if (!cap_sys_admin)
1350 free -= free / 32;
1352 if (free > pages)
1353 return 0;
1356 * nr_free_pages() is very expensive on large systems,
1357 * only call if we're about to fail.
1359 n = nr_free_pages();
1362 * Leave reserved pages. The pages are not for anonymous pages.
1364 if (n <= totalreserve_pages)
1365 goto error;
1366 else
1367 n -= totalreserve_pages;
1370 * Leave the last 3% for root
1372 if (!cap_sys_admin)
1373 n -= n / 32;
1374 free += n;
1376 if (free > pages)
1377 return 0;
1379 goto error;
1382 allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1384 * Leave the last 3% for root
1386 if (!cap_sys_admin)
1387 allowed -= allowed / 32;
1388 allowed += total_swap_pages;
1390 /* Don't let a single process grow too big:
1391 leave 3% of the size of this process for other processes */
1392 allowed -= current->mm->total_vm / 32;
1395 * cast `allowed' as a signed long because vm_committed_space
1396 * sometimes has a negative value
1398 if (atomic_read(&vm_committed_space) < (long)allowed)
1399 return 0;
1400 error:
1401 vm_unacct_memory(pages);
1403 return -ENOMEM;
1406 int in_gate_area_no_task(unsigned long addr)
1408 return 0;
1411 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1413 BUG();
1414 return 0;
1416 EXPORT_SYMBOL(filemap_fault);
1419 * Access another process' address space.
1420 * - source/target buffer must be kernel space
1422 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1424 struct vm_area_struct *vma;
1425 struct mm_struct *mm;
1427 if (addr + len < addr)
1428 return 0;
1430 mm = get_task_mm(tsk);
1431 if (!mm)
1432 return 0;
1434 down_read(&mm->mmap_sem);
1436 /* the access must start within one of the target process's mappings */
1437 vma = find_vma(mm, addr);
1438 if (vma) {
1439 /* don't overrun this mapping */
1440 if (addr + len >= vma->vm_end)
1441 len = vma->vm_end - addr;
1443 /* only read or write mappings where it is permitted */
1444 if (write && vma->vm_flags & VM_MAYWRITE)
1445 len -= copy_to_user((void *) addr, buf, len);
1446 else if (!write && vma->vm_flags & VM_MAYREAD)
1447 len -= copy_from_user(buf, (void *) addr, len);
1448 else
1449 len = 0;
1450 } else {
1451 len = 0;
1454 up_read(&mm->mmap_sem);
1455 mmput(mm);
1456 return len;