nommu.c

			    ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
			    ) {
				capabilities &= ~BDI_CAP_MAP_DIRECT;
				if (flags & MAP_SHARED) {
					printk(KERN_WARNING
					       "MAP_SHARED not completely supported on !MMU\n");
					return -EINVAL;
				}
			}
		}

		/* handle executable mappings and implied executable
		 * mappings */
		if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
			if (prot & PROT_EXEC)
				return -EPERM;
		}
		else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
			/* handle implication of PROT_EXEC by PROT_READ */
			if (current->personality & READ_IMPLIES_EXEC) {
				if (capabilities & BDI_CAP_EXEC_MAP)
					prot |= PROT_EXEC;
			}
		}
		else if ((prot & PROT_READ) &&
			 (prot & PROT_EXEC) &&
			 !(capabilities & BDI_CAP_EXEC_MAP)
			 ) {
			/* backing file is not executable, try to copy */
			capabilities &= ~BDI_CAP_MAP_DIRECT;
		}
	}
	else {
		/* anonymous mappings are always memory backed and can be
		 * privately mapped
		 */
		capabilities = BDI_CAP_MAP_COPY;

		/* handle PROT_EXEC implication by PROT_READ */
		if ((prot & PROT_READ) &&
		    (current->personality & READ_IMPLIES_EXEC))
			prot |= PROT_EXEC;
	}

	/* allow the security API to have its say */
	ret = security_mmap_addr(addr);
	if (ret < 0)
		return ret;

	/* looks okay */
	*_capabilities = capabilities;
	return 0;
}

/*
 * we've determined that we can make the mapping, now translate what we
 * now know into VMA flags
 */
static unsigned long determine_vm_flags(struct file *file,
					unsigned long prot,
					unsigned long flags,
					unsigned long capabilities)
{
	unsigned long vm_flags;

	vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
	/* vm_flags |= mm->def_flags; */

	if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
		/* attempt to share read-only copies of mapped file chunks */
		vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
		if (file && !(prot & PROT_WRITE))
			vm_flags |= VM_MAYSHARE;
	} else {
		/* overlay a shareable mapping on the backing device or inode
		 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
		 * romfs/cramfs */
		vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
		if (flags & MAP_SHARED)
			vm_flags |= VM_SHARED;
	}

	/* refuse to let anyone share private mappings with this process if
	 * it's being traced - otherwise breakpoints set in it may interfere
	 * with another untraced process
	 */
	if ((flags & MAP_PRIVATE) && current->ptrace)
		vm_flags &= ~VM_MAYSHARE;

	return vm_flags;
}

/*
 * set up a shared mapping on a file (the driver or filesystem provides and
 * pins the storage)
 */
static int do_mmap_shared_file(struct vm_area_struct *vma)
{
	int ret;

	ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
	if (ret == 0) {
		vma->vm_region->vm_top = vma->vm_region->vm_end;
		return 0;
	}
	if (ret != -ENOSYS)
		return ret;

	/* getting -ENOSYS indicates that direct mmap isn't possible (as
	 * opposed to tried but failed) so we can only give a suitable error as
	 * it's not possible to make a private copy if MAP_SHARED was given */
	return -ENODEV;
}

/*
 * set up a private mapping or an anonymous shared mapping
 */
static int do_mmap_private(struct vm_area_struct *vma,
			   struct vm_region *region,
			   unsigned long len,
			   unsigned long capabilities)
{
	struct page *pages;
	unsigned long total, point, n;
	void *base;
	int ret, order;

	/* invoke the file's mapping function so that it can keep track of
	 * shared mappings on devices or memory
	 * - VM_MAYSHARE will be set if it may attempt to share
	 */
	if (capabilities & BDI_CAP_MAP_DIRECT) {
		ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
		if (ret == 0) {
			/* shouldn't return success if we're not sharing */
			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
			vma->vm_region->vm_top = vma->vm_region->vm_end;
			return 0;
		}
		if (ret != -ENOSYS)
			return ret;

		/* getting an ENOSYS error indicates that direct mmap isn't
		 * possible (as opposed to tried but failed) so we'll try to
		 * make a private copy of the data and map that instead */
	}


	/* allocate some memory to hold the mapping
	 * - note that this may not return a page-aligned address if the object
	 *   we're allocating is smaller than a page
	 */
	order = get_order(len);
	kdebug("alloc order %d for %lx", order, len);

	pages = alloc_pages(GFP_KERNEL, order);
	if (!pages)
		goto enomem;

	total = 1 << order;
	atomic_long_add(total, &mmap_pages_allocated);

	point = len >> PAGE_SHIFT;

	/* we allocated a power-of-2 sized page set, so we may want to trim off
	 * the excess */
	if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
		while (total > point) {
			order = ilog2(total - point);
			n = 1 << order;
			kdebug("shave %lu/%lu @%lu", n, total - point, total);
			atomic_long_sub(n, &mmap_pages_allocated);
			total -= n;
			set_page_refcounted(pages + total);
			__free_pages(pages + total, order);
		}
	}

	for (point = 1; point < total; point++)
		set_page_refcounted(&pages[point]);

	base = page_address(pages);
	region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
	region->vm_start = (unsigned long) base;
	region->vm_end   = region->vm_start + len;
	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);

	vma->vm_start = region->vm_start;
	vma->vm_end   = region->vm_start + len;

	if (vma->vm_file) {
		/* read the contents of a file into the copy */
		mm_segment_t old_fs;
		loff_t fpos;

		fpos = vma->vm_pgoff;
		fpos <<= PAGE_SHIFT;

		old_fs = get_fs();
		set_fs(KERNEL_DS);
		ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
		set_fs(old_fs);

		if (ret < 0)
			goto error_free;

		/* clear the last little bit */
		if (ret < len)
			memset(base + ret, 0, len - ret);

	}

	return 0;

error_free:
	free_page_series(region->vm_start, region->vm_top);
	region->vm_start = vma->vm_start = 0;
	region->vm_end   = vma->vm_end = 0;
	region->vm_top   = 0;
	return ret;

enomem:
	printk("Allocation of length %lu from process %d (%s) failed\n",
	       len, current->pid, current->comm);
	show_free_areas(0);
	return -ENOMEM;
}

/*
 * handle mapping creation for uClinux
 */
unsigned long do_mmap_pgoff(struct file *file,
			    unsigned long addr,
			    unsigned long len,
			    unsigned long prot,
			    unsigned long flags,
			    unsigned long pgoff)
{
	struct vm_area_struct *vma;
	struct vm_region *region;
	struct rb_node *rb;
	unsigned long capabilities, vm_flags, result;
	int ret;

	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);

	/* decide whether we should attempt the mapping, and if so what sort of
	 * mapping */
	ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
				    &capabilities);
	if (ret < 0) {
		kleave(" = %d [val]", ret);
		return ret;
	}

	/* we ignore the address hint */
	addr = 0;
	len = PAGE_ALIGN(len);

	/* we've determined that we can make the mapping, now translate what we
	 * now know into VMA flags */
	vm_flags = determine_vm_flags(file, prot, flags, capabilities);

	/* we're going to need to record the mapping */
	region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		goto error_getting_region;

	vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
	if (!vma)
		goto error_getting_vma;

	region->vm_usage = 1;
	region->vm_flags = vm_flags;
	region->vm_pgoff = pgoff;

	INIT_LIST_HEAD(&vma->anon_vma_chain);
	vma->vm_flags = vm_flags;
	vma->vm_pgoff = pgoff;

	if (file) {
		region->vm_file = get_file(file);
		vma->vm_file = get_file(file);
	}

	down_write(&nommu_region_sem);

	/* if we want to share, we need to check for regions created by other
	 * mmap() calls that overlap with our proposed mapping
	 * - we can only share with a superset match on most regular files
	 * - shared mappings on character devices and memory backed files are
	 *   permitted to overlap inexactly as far as we are concerned for in
	 *   these cases, sharing is handled in the driver or filesystem rather
	 *   than here
	 */
	if (vm_flags & VM_MAYSHARE) {
		struct vm_region *pregion;
		unsigned long pglen, rpglen, pgend, rpgend, start;

		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		pgend = pgoff + pglen;

		for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
			pregion = rb_entry(rb, struct vm_region, vm_rb);

			if (!(pregion->vm_flags & VM_MAYSHARE))
				continue;

			/* search for overlapping mappings on the same file */
			if (pregion->vm_file->f_path.dentry->d_inode !=
			    file->f_path.dentry->d_inode)
				continue;

			if (pregion->vm_pgoff >= pgend)
				continue;

			rpglen = pregion->vm_end - pregion->vm_start;
			rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
			rpgend = pregion->vm_pgoff + rpglen;
			if (pgoff >= rpgend)
				continue;

			/* handle inexactly overlapping matches between
			 * mappings */
			if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
			    !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
				/* new mapping is not a subset of the region */
				if (!(capabilities & BDI_CAP_MAP_DIRECT))
					goto sharing_violation;
				continue;
			}

			/* we've found a region we can share */
			pregion->vm_usage++;
			vma->vm_region = pregion;
			start = pregion->vm_start;
			start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
			vma->vm_start = start;
			vma->vm_end = start + len;

			if (pregion->vm_flags & VM_MAPPED_COPY) {
				kdebug("share copy");
				vma->vm_flags |= VM_MAPPED_COPY;
			} else {
				kdebug("share mmap");
				ret = do_mmap_shared_file(vma);
				if (ret < 0) {
					vma->vm_region = NULL;
					vma->vm_start = 0;
					vma->vm_end = 0;
					pregion->vm_usage--;
					pregion = NULL;
					goto error_just_free;
				}
			}
			fput(region->vm_file);
			kmem_cache_free(vm_region_jar, region);
			region = pregion;
			result = start;
			goto share;
		}

		/* obtain the address at which to make a shared mapping
		 * - this is the hook for quasi-memory character devices to
		 *   tell us the location of a shared mapping
		 */
		if (capabilities & BDI_CAP_MAP_DIRECT) {
			addr = file->f_op->get_unmapped_area(file, addr, len,
							     pgoff, flags);
			if (IS_ERR_VALUE(addr)) {
				ret = addr;
				if (ret != -ENOSYS)
					goto error_just_free;

				/* the driver refused to tell us where to site
				 * the mapping so we'll have to attempt to copy
				 * it */
				ret = -ENODEV;
				if (!(capabilities & BDI_CAP_MAP_COPY))
					goto error_just_free;

				capabilities &= ~BDI_CAP_MAP_DIRECT;
			} else {
				vma->vm_start = region->vm_start = addr;
				vma->vm_end = region->vm_end = addr + len;
			}
		}
	}

	vma->vm_region = region;

	/* set up the mapping
	 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
	 */
	if (file && vma->vm_flags & VM_SHARED)
		ret = do_mmap_shared_file(vma);
	else
		ret = do_mmap_private(vma, region, len, capabilities);
	if (ret < 0)
		goto error_just_free;
	add_nommu_region(region);

	/* clear anonymous mappings that don't ask for uninitialized data */
	if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
		memset((void *)region->vm_start, 0,
		       region->vm_end - region->vm_start);

	/* okay... we have a mapping; now we have to register it */
	result = vma->vm_start;

	current->mm->total_vm += len >> PAGE_SHIFT;

share:
	add_vma_to_mm(current->mm, vma);

	/* we flush the region from the icache only when the first executable
	 * mapping of it is made  */
	if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
		flush_icache_range(region->vm_start, region->vm_end);
		region->vm_icache_flushed = true;
	}

	up_write(&nommu_region_sem);

	kleave(" = %lx", result);
	return result;

error_just_free:
	up_write(&nommu_region_sem);
error:
	if (region->vm_file)
		fput(region->vm_file);
	kmem_cache_free(vm_region_jar, region);
	if (vma->vm_file)
		fput(vma->vm_file);
	kmem_cache_free(vm_area_cachep, vma);
	kleave(" = %d", ret);
	return ret;

sharing_violation:
	up_write(&nommu_region_sem);
	printk(KERN_WARNING "Attempt to share mismatched mappings\n");
	ret = -EINVAL;
	goto error;

error_getting_vma:
	kmem_cache_free(vm_region_jar, region);
	printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
	       " from process %d failed\n",
	       len, current->pid);
	show_free_areas(0);
	return -ENOMEM;

error_getting_region:
	printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
	       " from process %d failed\n",
	       len, current->pid);
	show_free_areas(0);
	return -ENOMEM;
}

SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
		unsigned long, prot, unsigned long, flags,
		unsigned long, fd, unsigned long, pgoff)
{
	struct file *file = NULL;
	unsigned long retval = -EBADF;

	audit_mmap_fd(fd, flags);
	if (!(flags & MAP_ANONYMOUS)) {
		file = fget(fd);
		if (!file)
			goto out;
	}

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

	retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);

	if (file)
		fput(file);
out:
	return retval;
}

#ifdef __ARCH_WANT_SYS_OLD_MMAP
struct mmap_arg_struct {
	unsigned long addr;
	unsigned long len;
	unsigned long prot;
	unsigned long flags;
	unsigned long fd;
	unsigned long offset;
};

SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
{
	struct mmap_arg_struct a;

	if (copy_from_user(&a, arg, sizeof(a)))
		return -EFAULT;
	if (a.offset & ~PAGE_MASK)
		return -EINVAL;

	return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
			      a.offset >> PAGE_SHIFT);
}
#endif /* __ARCH_WANT_SYS_OLD_MMAP */

/*
 * split a vma into two pieces at address 'addr', a new vma is allocated either
 * for the first part or the tail.
 */
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
	      unsigned long addr, int new_below)
{
	struct vm_area_struct *new;
	struct vm_region *region;
	unsigned long npages;

	kenter("");

	/* we're only permitted to split anonymous regions (these should have
	 * only a single usage on the region) */
	if (vma->vm_file)
		return -ENOMEM;

	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;

	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		return -ENOMEM;

	new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
	if (!new) {
		kmem_cache_free(vm_region_jar, region);
		return -ENOMEM;
	}

	/* most fields are the same, copy all, and then fixup */
	*new = *vma;
	*region = *vma->vm_region;
	new->vm_region = region;

	npages = (addr - vma->vm_start) >> PAGE_SHIFT;

	if (new_below) {
		region->vm_top = region->vm_end = new->vm_end = addr;
	} else {
		region->vm_start = new->vm_start = addr;
		region->vm_pgoff = new->vm_pgoff += npages;
	}

	if (new->vm_ops && new->vm_ops->open)
		new->vm_ops->open(new);

	delete_vma_from_mm(vma);
	down_write(&nommu_region_sem);
	delete_nommu_region(vma->vm_region);
	if (new_below) {
		vma->vm_region->vm_start = vma->vm_start = addr;
		vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
	} else {
		vma->vm_region->vm_end = vma->vm_end = addr;
		vma->vm_region->vm_top = addr;
	}
	add_nommu_region(vma->vm_region);
	add_nommu_region(new->vm_region);
	up_write(&nommu_region_sem);
	add_vma_to_mm(mm, vma);
	add_vma_to_mm(mm, new);
	return 0;
}

/*
 * shrink a VMA by removing the specified chunk from either the beginning or
 * the end
 */
static int shrink_vma(struct mm_struct *mm,
		      struct vm_area_struct *vma,
		      unsigned long from, unsigned long to)
{
	struct vm_region *region;

	kenter("");

	/* adjust the VMA's pointers, which may reposition it in the MM's tree
	 * and list */
	delete_vma_from_mm(vma);
	if (from > vma->vm_start)
		vma->vm_end = from;
	else
		vma->vm_start = to;
	add_vma_to_mm(mm, vma);

	/* cut the backing region down to size */
	region = vma->vm_region;
	BUG_ON(region->vm_usage != 1);

	down_write(&nommu_region_sem);
	delete_nommu_region(region);
	if (from > region->vm_start) {
		to = region->vm_top;
		region->vm_top = region->vm_end = from;
	} else {
		region->vm_start = to;
	}
	add_nommu_region(region);
	up_write(&nommu_region_sem);

	free_page_series(from, to);
	return 0;
}

/*
 * release a mapping
 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
 *   VMA, though it need not cover the whole VMA
 */
int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
	struct vm_area_struct *vma;
	unsigned long end;
	int ret;

	kenter(",%lx,%zx", start, len);

	len = PAGE_ALIGN(len);
	if (len == 0)
		return -EINVAL;

	end = start + len;

	/* find the first potentially overlapping VMA */
	vma = find_vma(mm, start);
	if (!vma) {
		static int limit = 0;
		if (limit < 5) {
			printk(KERN_WARNING
			       "munmap of memory not mmapped by process %d"
			       " (%s): 0x%lx-0x%lx\n",
			       current->pid, current->comm,
			       start, start + len - 1);
			limit++;
		}
		return -EINVAL;
	}

	/* we're allowed to split an anonymous VMA but not a file-backed one */
	if (vma->vm_file) {
		do {
			if (start > vma->vm_start) {
				kleave(" = -EINVAL [miss]");
				return -EINVAL;
			}
			if (end == vma->vm_end)
				goto erase_whole_vma;
			vma = vma->vm_next;
		} while (vma);
		kleave(" = -EINVAL [split file]");
		return -EINVAL;
	} else {
		/* the chunk must be a subset of the VMA found */
		if (start == vma->vm_start && end == vma->vm_end)
			goto erase_whole_vma;
		if (start < vma->vm_start || end > vma->vm_end) {
			kleave(" = -EINVAL [superset]");
			return -EINVAL;
		}
		if (start & ~PAGE_MASK) {
			kleave(" = -EINVAL [unaligned start]");
			return -EINVAL;
		}
		if (end != vma->vm_end && end & ~PAGE_MASK) {
			kleave(" = -EINVAL [unaligned split]");
			return -EINVAL;
		}
		if (start != vma->vm_start && end != vma->vm_end) {
			ret = split_vma(mm, vma, start, 1);
			if (ret < 0) {
				kleave(" = %d [split]", ret);
				return ret;
			}
		}
		return shrink_vma(mm, vma, start, end);
	}

erase_whole_vma:
	delete_vma_from_mm(vma);
	delete_vma(mm, vma);
	kleave(" = 0");
	return 0;
}
EXPORT_SYMBOL(do_munmap);

int vm_munmap(unsigned long addr, size_t len)
{
	struct mm_struct *mm = current->mm;
	int ret;

	down_write(&mm->mmap_sem);
	ret = do_munmap(mm, addr, len);
	up_write(&mm->mmap_sem);
	return ret;
}
EXPORT_SYMBOL(vm_munmap);

SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
{
	return vm_munmap(addr, len);
}

/*
 * release all the mappings made in a process's VM space
 */
void exit_mmap(struct mm_struct *mm)
{
	struct vm_area_struct *vma;

	if (!mm)
		return;

	kenter("");

	mm->total_vm = 0;

	while ((vma = mm->mmap)) {
		mm->mmap = vma->vm_next;
		delete_vma_from_mm(vma);
		delete_vma(mm, vma);
		cond_resched();
	}

	kleave("");
}

unsigned long vm_brk(unsigned long addr, unsigned long len)
{
	return -ENOMEM;
}

/*
 * expand (or shrink) an existing mapping, potentially moving it at the same
 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
 *
 * under NOMMU conditions, we only permit changing a mapping's size, and only
 * as long as it stays within the region allocated by do_mmap_private() and the
 * block is not shareable
 *
 * MREMAP_FIXED is not supported under NOMMU conditions
 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
	struct vm_area_struct *vma;

	/* insanity checks first */
	old_len = PAGE_ALIGN(old_len);
	new_len = PAGE_ALIGN(new_len);
	if (old_len == 0 || new_len == 0)
		return (unsigned long) -EINVAL;

	if (addr & ~PAGE_MASK)
		return -EINVAL;

	if (flags & MREMAP_FIXED && new_addr != addr)
		return (unsigned long) -EINVAL;

	vma = find_vma_exact(current->mm, addr, old_len);
	if (!vma)
		return (unsigned long) -EINVAL;

	if (vma->vm_end != vma->vm_start + old_len)
		return (unsigned long) -EFAULT;

	if (vma->vm_flags & VM_MAYSHARE)
		return (unsigned long) -EPERM;

	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
		return (unsigned long) -ENOMEM;

	/* all checks complete - do it */
	vma->vm_end = vma->vm_start + new_len;
	return vma->vm_start;
}
EXPORT_SYMBOL(do_mremap);

SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
		unsigned long, new_len, unsigned long, flags,
		unsigned long, new_addr)
{
	unsigned long ret;

	down_write(&current->mm->mmap_sem);
	ret = do_mremap(addr, old_len, new_len, flags, new_addr);
	up_write(&current->mm->mmap_sem);
	return ret;
}

struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
			unsigned int foll_flags)
{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
		unsigned long pfn, unsigned long size, pgprot_t prot)
{
	if (addr != (pfn << PAGE_SHIFT))
		return -EINVAL;

	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
	return 0;
}
EXPORT_SYMBOL(remap_pfn_range);

int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
			unsigned long pgoff)
{
	unsigned int size = vma->vm_end - vma->vm_start;

	if (!(vma->vm_flags & VM_USERMAP))
		return -EINVAL;

	vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
	vma->vm_end = vma->vm_start + size;

	return 0;
}
EXPORT_SYMBOL(remap_vmalloc_range);

unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
	unsigned long len, unsigned long pgoff, unsigned long flags)
{
	return -ENOMEM;
}

void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
EXPORT_SYMBOL(unmap_mapping_range);

/*
 * Check that a process has enough memory to allocate a new virtual
 * mapping. 0 means there is enough memory for the allocation to
 * succeed and -ENOMEM implies there is not.
 *
 * We currently support three overcommit policies, which are set via the
 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
 *
 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
 * Additional code 2002 Jul 20 by Robert Love.
 *
 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
 *
 * Note this is a helper function intended to be used by LSMs which
 * wish to use this logic.
 */
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
{
	unsigned long free, allowed;

	vm_acct_memory(pages);

	/*
	 * Sometimes we want to use more memory than we have
	 */
	if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
		return 0;

	if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
		free = global_page_state(NR_FREE_PAGES);
		free += global_page_state(NR_FILE_PAGES);

		/*
		 * shmem pages shouldn't be counted as free in this
		 * case, they can't be purged, only swapped out, and
		 * that won't affect the overall amount of available
		 * memory in the system.
		 */
		free -= global_page_state(NR_SHMEM);

		free += nr_swap_pages;

		/*
		 * Any slabs which are created with the
		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
		 * which are reclaimable, under pressure.  The dentry
		 * cache and most inode caches should fall into this
		 */
		free += global_page_state(NR_SLAB_RECLAIMABLE);

		/*
		 * Leave reserved pages. The pages are not for anonymous pages.
		 */
		if (free <= totalreserve_pages)
			goto error;
		else
			free -= totalreserve_pages;

		/*
		 * Leave the last 3% for root
		 */
		if (!cap_sys_admin)
			free -= free / 32;

		if (free > pages)
			return 0;

		goto error;
	}

	allowed = totalram_pages * sysctl_overcommit_ratio / 100;
	/*
	 * Leave the last 3% for root
	 */
	if (!cap_sys_admin)
		allowed -= allowed / 32;
	allowed += total_swap_pages;

	/* Don't let a single process grow too big:
	   leave 3% of the size of this process for other processes */
	if (mm)
		allowed -= mm->total_vm / 32;

	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
		return 0;

error:
	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_mm(unsigned long addr)
{
	return 0;
}

int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
	BUG();
	return 0;
}
EXPORT_SYMBOL(filemap_fault);

int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
			     unsigned long size, pgoff_t pgoff)
{
	BUG();
	return 0;
}
EXPORT_SYMBOL(generic_file_remap_pages);

static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
{
	struct vm_area_struct *vma;

	down_read(&mm->mmap_sem);

	/* the access must start within one of the target process's mappings */
	vma = find_vma(mm, addr);
	if (vma) {
		/* don't overrun this mapping */
		if (addr + len >= vma->vm_end)
			len = vma->vm_end - addr;

		/* only read or write mappings where it is permitted */
		if (write && vma->vm_flags & VM_MAYWRITE)
			copy_to_user_page(vma, NULL, addr,
					 (void *) addr, buf, len);
		else if (!write && vma->vm_flags & VM_MAYREAD)
			copy_from_user_page(vma, NULL, addr,
					    buf, (void *) addr, len);
		else
			len = 0;
	} else {
		len = 0;
	}

	up_read(&mm->mmap_sem);

	return len;
}

/**
 * @access_remote_vm - access another process' address space
 * @mm:		the mm_struct of the target address space
 * @addr:	start address to access
 * @buf:	source or destination buffer
 * @len:	number of bytes to transfer