nommu.c 32.4 KB
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/*
 *  linux/mm/nommu.c
 *
 *  Replacement code for mm functions to support CPU's that don't
 *  have any form of memory management unit (thus no virtual memory).
 *
 *  See Documentation/nommu-mmap.txt
 *
 *  Copyright (c) 2004-2005 David Howells <dhowells@redhat.com>
 *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
 *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
 *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
 */

#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/file.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/ptrace.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>

#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

void *high_memory;
struct page *mem_map;
unsigned long max_mapnr;
unsigned long num_physpages;
unsigned long askedalloc, realalloc;
atomic_t vm_committed_space = ATOMIC_INIT(0);
int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
int sysctl_overcommit_ratio = 50; /* default is 50% */
int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
int heap_stack_gap = 0;

EXPORT_SYMBOL(mem_map);
EXPORT_SYMBOL(__vm_enough_memory);
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EXPORT_SYMBOL(num_physpages);
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/* list of shareable VMAs */
struct rb_root nommu_vma_tree = RB_ROOT;
DECLARE_RWSEM(nommu_vma_sem);

struct vm_operations_struct generic_file_vm_ops = {
};

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EXPORT_SYMBOL(vfree);
EXPORT_SYMBOL(vmalloc_to_page);
EXPORT_SYMBOL(vmalloc_32);
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EXPORT_SYMBOL(vmap);
EXPORT_SYMBOL(vunmap);
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/*
 * Handle all mappings that got truncated by a "truncate()"
 * system call.
 *
 * NOTE! We have to be ready to update the memory sharing
 * between the file and the memory map for a potential last
 * incomplete page.  Ugly, but necessary.
 */
int vmtruncate(struct inode *inode, loff_t offset)
{
	struct address_space *mapping = inode->i_mapping;
	unsigned long limit;

	if (inode->i_size < offset)
		goto do_expand;
	i_size_write(inode, offset);

	truncate_inode_pages(mapping, offset);
	goto out_truncate;

do_expand:
	limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
	if (limit != RLIM_INFINITY && offset > limit)
		goto out_sig;
	if (offset > inode->i_sb->s_maxbytes)
		goto out;
	i_size_write(inode, offset);

out_truncate:
	if (inode->i_op && inode->i_op->truncate)
		inode->i_op->truncate(inode);
	return 0;
out_sig:
	send_sig(SIGXFSZ, current, 0);
out:
	return -EFBIG;
}

EXPORT_SYMBOL(vmtruncate);

/*
 * Return the total memory allocated for this pointer, not
 * just what the caller asked for.
 *
 * Doesn't have to be accurate, i.e. may have races.
 */
unsigned int kobjsize(const void *objp)
{
	struct page *page;

	if (!objp || !((page = virt_to_page(objp))))
		return 0;

	if (PageSlab(page))
		return ksize(objp);

	BUG_ON(page->index < 0);
	BUG_ON(page->index >= MAX_ORDER);

	return (PAGE_SIZE << page->index);
}

/*
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 * get a list of pages in an address range belonging to the specified process
 * and indicate the VMA that covers each page
 * - this is potentially dodgy as we may end incrementing the page count of a
 *   slab page or a secondary page from a compound page
 * - don't permit access to VMAs that don't support it, such as I/O mappings
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 */
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
	unsigned long start, int len, int write, int force,
	struct page **pages, struct vm_area_struct **vmas)
{
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	struct vm_area_struct *vma;
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	unsigned long vm_flags;
	int i;

	/* calculate required read or write permissions.
	 * - if 'force' is set, we only require the "MAY" flags.
	 */
	vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
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	for (i = 0; i < len; i++) {
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		vma = find_vma(mm, start);
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		if (!vma)
			goto finish_or_fault;

		/* protect what we can, including chardevs */
		if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
		    !(vm_flags & vma->vm_flags))
			goto finish_or_fault;
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		if (pages) {
			pages[i] = virt_to_page(start);
			if (pages[i])
				page_cache_get(pages[i]);
		}
		if (vmas)
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			vmas[i] = vma;
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		start += PAGE_SIZE;
	}
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	return i;

finish_or_fault:
	return i ? : -EFAULT;
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}

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EXPORT_SYMBOL(get_user_pages);

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DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;

void vfree(void *addr)
{
	kfree(addr);
}

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void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
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{
	/*
	 * kmalloc doesn't like __GFP_HIGHMEM for some reason
	 */
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	return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
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}

struct page * vmalloc_to_page(void *addr)
{
	return virt_to_page(addr);
}

unsigned long vmalloc_to_pfn(void *addr)
{
	return page_to_pfn(virt_to_page(addr));
}


long vread(char *buf, char *addr, unsigned long count)
{
	memcpy(buf, addr, count);
	return count;
}

long vwrite(char *buf, char *addr, unsigned long count)
{
	/* Don't allow overflow */
	if ((unsigned long) addr + count < count)
		count = -(unsigned long) addr;

	memcpy(addr, buf, count);
	return(count);
}

/*
 *	vmalloc  -  allocate virtually continguos memory
 *
 *	@size:		allocation size
 *
 *	Allocate enough pages to cover @size from the page level
 *	allocator and map them into continguos kernel virtual space.
 *
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 *	For tight control over page level allocator and protection flags
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 *	use __vmalloc() instead.
 */
void *vmalloc(unsigned long size)
{
       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
}
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EXPORT_SYMBOL(vmalloc);

void *vmalloc_node(unsigned long size, int node)
{
	return vmalloc(size);
}
EXPORT_SYMBOL(vmalloc_node);
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/*
 *	vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
 *
 *	@size:		allocation size
 *
 *	Allocate enough 32bit PA addressable pages to cover @size from the
 *	page level allocator and map them into continguos kernel virtual space.
 */
void *vmalloc_32(unsigned long size)
{
	return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
}

void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
{
	BUG();
	return NULL;
}

void vunmap(void *addr)
{
	BUG();
}

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/*
 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 * have one.
 */
void  __attribute__((weak)) vmalloc_sync_all(void)
{
}

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/*
 *  sys_brk() for the most part doesn't need the global kernel
 *  lock, except when an application is doing something nasty
 *  like trying to un-brk an area that has already been mapped
 *  to a regular file.  in this case, the unmapping will need
 *  to invoke file system routines that need the global lock.
 */
asmlinkage unsigned long sys_brk(unsigned long brk)
{
	struct mm_struct *mm = current->mm;

	if (brk < mm->start_brk || brk > mm->context.end_brk)
		return mm->brk;

	if (mm->brk == brk)
		return mm->brk;

	/*
	 * Always allow shrinking brk
	 */
	if (brk <= mm->brk) {
		mm->brk = brk;
		return brk;
	}

	/*
	 * Ok, looks good - let it rip.
	 */
	return mm->brk = brk;
}

#ifdef DEBUG
static void show_process_blocks(void)
{
	struct vm_list_struct *vml;

	printk("Process blocks %d:", current->pid);

	for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
		printk(" %p: %p", vml, vml->vma);
		if (vml->vma)
			printk(" (%d @%lx #%d)",
			       kobjsize((void *) vml->vma->vm_start),
			       vml->vma->vm_start,
			       atomic_read(&vml->vma->vm_usage));
		printk(vml->next ? " ->" : ".\n");
	}
}
#endif /* DEBUG */

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/*
 * add a VMA into a process's mm_struct in the appropriate place in the list
 * - should be called with mm->mmap_sem held writelocked
 */
static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
{
	struct vm_list_struct **ppv;

	for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
		if ((*ppv)->vma->vm_start > vml->vma->vm_start)
			break;

	vml->next = *ppv;
	*ppv = vml;
}

/*
 * look up the first VMA in which addr resides, NULL if none
 * - should be called with mm->mmap_sem at least held readlocked
 */
struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
{
	struct vm_list_struct *loop, *vml;

	/* search the vm_start ordered list */
	vml = NULL;
	for (loop = mm->context.vmlist; loop; loop = loop->next) {
		if (loop->vma->vm_start > addr)
			break;
		vml = loop;
	}

	if (vml && vml->vma->vm_end > addr)
		return vml->vma;

	return NULL;
}
EXPORT_SYMBOL(find_vma);

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/*
 * find a VMA
 * - we don't extend stack VMAs under NOMMU conditions
 */
struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
{
	return find_vma(mm, addr);
}

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int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return -ENOMEM;
}

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/*
 * look up the first VMA exactly that exactly matches addr
 * - should be called with mm->mmap_sem at least held readlocked
 */
static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
						    unsigned long addr)
{
	struct vm_list_struct *vml;

	/* search the vm_start ordered list */
	for (vml = mm->context.vmlist; vml; vml = vml->next) {
		if (vml->vma->vm_start == addr)
			return vml->vma;
		if (vml->vma->vm_start > addr)
			break;
	}

	return NULL;
}

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/*
 * find a VMA in the global tree
 */
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static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
{
	struct vm_area_struct *vma;
	struct rb_node *n = nommu_vma_tree.rb_node;

	while (n) {
		vma = rb_entry(n, struct vm_area_struct, vm_rb);

		if (start < vma->vm_start)
			n = n->rb_left;
		else if (start > vma->vm_start)
			n = n->rb_right;
		else
			return vma;
	}

	return NULL;
}

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/*
 * add a VMA in the global tree
 */
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static void add_nommu_vma(struct vm_area_struct *vma)
{
	struct vm_area_struct *pvma;
	struct address_space *mapping;
	struct rb_node **p = &nommu_vma_tree.rb_node;
	struct rb_node *parent = NULL;

	/* add the VMA to the mapping */
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;

		flush_dcache_mmap_lock(mapping);
		vma_prio_tree_insert(vma, &mapping->i_mmap);
		flush_dcache_mmap_unlock(mapping);
	}

	/* add the VMA to the master list */
	while (*p) {
		parent = *p;
		pvma = rb_entry(parent, struct vm_area_struct, vm_rb);

		if (vma->vm_start < pvma->vm_start) {
			p = &(*p)->rb_left;
		}
		else if (vma->vm_start > pvma->vm_start) {
			p = &(*p)->rb_right;
		}
		else {
			/* mappings are at the same address - this can only
			 * happen for shared-mem chardevs and shared file
			 * mappings backed by ramfs/tmpfs */
			BUG_ON(!(pvma->vm_flags & VM_SHARED));

			if (vma < pvma)
				p = &(*p)->rb_left;
			else if (vma > pvma)
				p = &(*p)->rb_right;
			else
				BUG();
		}
	}

	rb_link_node(&vma->vm_rb, parent, p);
	rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
}

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/*
 * delete a VMA from the global list
 */
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static void delete_nommu_vma(struct vm_area_struct *vma)
{
	struct address_space *mapping;

	/* remove the VMA from the mapping */
	if (vma->vm_file) {
		mapping = vma->vm_file->f_mapping;

		flush_dcache_mmap_lock(mapping);
		vma_prio_tree_remove(vma, &mapping->i_mmap);
		flush_dcache_mmap_unlock(mapping);
	}

	/* remove from the master list */
	rb_erase(&vma->vm_rb, &nommu_vma_tree);
}

/*
 * determine whether a mapping should be permitted and, if so, what sort of
 * mapping we're capable of supporting
 */
static int validate_mmap_request(struct file *file,
				 unsigned long addr,
				 unsigned long len,
				 unsigned long prot,
				 unsigned long flags,
				 unsigned long pgoff,
				 unsigned long *_capabilities)
{
	unsigned long capabilities;
	unsigned long reqprot = prot;
	int ret;

	/* do the simple checks first */
	if (flags & MAP_FIXED || addr) {
		printk(KERN_DEBUG
		       "%d: Can't do fixed-address/overlay mmap of RAM\n",
		       current->pid);
		return -EINVAL;
	}

	if ((flags & MAP_TYPE) != MAP_PRIVATE &&
	    (flags & MAP_TYPE) != MAP_SHARED)
		return -EINVAL;

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	if (!len)
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		return -EINVAL;

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	/* Careful about overflows.. */
	len = PAGE_ALIGN(len);
	if (!len || len > TASK_SIZE)
		return -ENOMEM;

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	/* offset overflow? */
	if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
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		return -EOVERFLOW;
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	if (file) {
		/* validate file mapping requests */
		struct address_space *mapping;

		/* files must support mmap */
		if (!file->f_op || !file->f_op->mmap)
			return -ENODEV;

		/* work out if what we've got could possibly be shared
		 * - we support chardevs that provide their own "memory"
		 * - we support files/blockdevs that are memory backed
		 */
		mapping = file->f_mapping;
		if (!mapping)
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			mapping = file->f_path.dentry->d_inode->i_mapping;
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		capabilities = 0;
		if (mapping && mapping->backing_dev_info)
			capabilities = mapping->backing_dev_info->capabilities;

		if (!capabilities) {
			/* no explicit capabilities set, so assume some
			 * defaults */
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			switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
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			case S_IFREG:
			case S_IFBLK:
				capabilities = BDI_CAP_MAP_COPY;
				break;

			case S_IFCHR:
				capabilities =
					BDI_CAP_MAP_DIRECT |
					BDI_CAP_READ_MAP |
					BDI_CAP_WRITE_MAP;
				break;

			default:
				return -EINVAL;
			}
		}

		/* eliminate any capabilities that we can't support on this
		 * device */
		if (!file->f_op->get_unmapped_area)
			capabilities &= ~BDI_CAP_MAP_DIRECT;
		if (!file->f_op->read)
			capabilities &= ~BDI_CAP_MAP_COPY;

		if (flags & MAP_SHARED) {
			/* do checks for writing, appending and locking */
			if ((prot & PROT_WRITE) &&
			    !(file->f_mode & FMODE_WRITE))
				return -EACCES;

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			if (IS_APPEND(file->f_path.dentry->d_inode) &&
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			    (file->f_mode & FMODE_WRITE))
				return -EACCES;

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			if (locks_verify_locked(file->f_path.dentry->d_inode))
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				return -EAGAIN;

			if (!(capabilities & BDI_CAP_MAP_DIRECT))
				return -ENODEV;

			if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
			    ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
			    ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
			    ) {
				printk("MAP_SHARED not completely supported on !MMU\n");
				return -EINVAL;
			}

			/* we mustn't privatise shared mappings */
			capabilities &= ~BDI_CAP_MAP_COPY;
		}
		else {
			/* we're going to read the file into private memory we
			 * allocate */
			if (!(capabilities & BDI_CAP_MAP_COPY))
				return -ENODEV;

			/* we don't permit a private writable mapping to be
			 * shared with the backing device */
			if (prot & PROT_WRITE)
				capabilities &= ~BDI_CAP_MAP_DIRECT;
		}

		/* handle executable mappings and implied executable
		 * mappings */
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		if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
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			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 */
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	ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
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	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 |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
	/* vm_flags |= mm->def_flags; */

	if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
		/* attempt to share read-only copies of mapped file chunks */
		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 */
		if (flags & MAP_SHARED)
			vm_flags |= VM_MAYSHARE | VM_SHARED;
		else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
			vm_flags |= VM_MAYSHARE;
	}

	/* 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 & PT_PTRACED))
		vm_flags &= ~VM_MAYSHARE;

	return vm_flags;
}

/*
 * set up a shared mapping on a file
 */
static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
{
	int ret;

	ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
	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 fall
	 * through to making a private copy of the data and mapping
	 * that if we can */
	return -ENODEV;
}

/*
 * set up a private mapping or an anonymous shared mapping
 */
static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
{
	void *base;
	int ret;

	/* 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 (vma->vm_file) {
		ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
		if (ret != -ENOSYS) {
			/* shouldn't return success if we're not sharing */
			BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
			return ret; /* success or a real error */
		}

		/* 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
	 */
743
	base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
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	if (!base)
		goto enomem;

	vma->vm_start = (unsigned long) base;
	vma->vm_end = vma->vm_start + len;
	vma->vm_flags |= VM_MAPPED_COPY;

#ifdef WARN_ON_SLACK
	if (len + WARN_ON_SLACK <= kobjsize(result))
		printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
		       len, current->pid, kobjsize(result) - len);
#endif

	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);

	} else {
		/* if it's an anonymous mapping, then just clear it */
		memset(base, 0, len);
	}

	return 0;

error_free:
	kfree(base);
	vma->vm_start = 0;
	return ret;

enomem:
	printk("Allocation of length %lu from process %d failed\n",
	       len, current->pid);
	show_free_areas();
	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_list_struct *vml = NULL;
	struct vm_area_struct *vma = NULL;
	struct rb_node *rb;
	unsigned long capabilities, vm_flags;
	void *result;
	int ret;

	/* 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)
		return ret;

	/* 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 if it works */
825
	vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
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	if (!vml)
		goto error_getting_vml;

	down_write(&nommu_vma_sem);

	/* if we want to share, we need to check for VMAs created by other
	 * mmap() calls that overlap with our proposed mapping
	 * - we can only share with an exact 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) {
		unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		unsigned long vmpglen;

843 844 845 846 847
		/* suppress VMA sharing for shared regions */
		if (vm_flags & VM_SHARED &&
		    capabilities & BDI_CAP_MAP_DIRECT)
			goto dont_share_VMAs;

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		for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
			vma = rb_entry(rb, struct vm_area_struct, vm_rb);

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

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

			if (vma->vm_pgoff >= pgoff + pglen)
				continue;

			vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
			vmpglen >>= PAGE_SHIFT;
			if (pgoff >= vma->vm_pgoff + vmpglen)
				continue;

			/* handle inexactly overlapping matches between mappings */
			if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
				if (!(capabilities & BDI_CAP_MAP_DIRECT))
					goto sharing_violation;
				continue;
			}

			/* we've found a VMA we can share */
			atomic_inc(&vma->vm_usage);

			vml->vma = vma;
			result = (void *) vma->vm_start;
			goto shared;
		}

881
	dont_share_VMAs:
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		vma = NULL;

		/* 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 (file && file->f_op->get_unmapped_area) {
			addr = file->f_op->get_unmapped_area(file, addr, len,
							     pgoff, flags);
			if (IS_ERR((void *) addr)) {
				ret = addr;
				if (ret != (unsigned long) -ENOSYS)
					goto error;

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

				capabilities &= ~BDI_CAP_MAP_DIRECT;
			}
		}
	}

	/* we're going to need a VMA struct as well */
909
	vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
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	if (!vma)
		goto error_getting_vma;

	INIT_LIST_HEAD(&vma->anon_vma_node);
	atomic_set(&vma->vm_usage, 1);
	if (file)
		get_file(file);
	vma->vm_file	= file;
	vma->vm_flags	= vm_flags;
	vma->vm_start	= addr;
	vma->vm_end	= addr + len;
	vma->vm_pgoff	= pgoff;

	vml->vma = vma;

	/* set up the mapping */
	if (file && vma->vm_flags & VM_SHARED)
		ret = do_mmap_shared_file(vma, len);
	else
		ret = do_mmap_private(vma, len);
	if (ret < 0)
		goto error;

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

	if (vma->vm_flags & VM_MAPPED_COPY) {
		realalloc += kobjsize(result);
		askedalloc += len;
	}

	realalloc += kobjsize(vma);
	askedalloc += sizeof(*vma);

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

	add_nommu_vma(vma);

 shared:
	realalloc += kobjsize(vml);
	askedalloc += sizeof(*vml);

952
	add_vma_to_mm(current->mm, vml);
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	up_write(&nommu_vma_sem);

	if (prot & PROT_EXEC)
		flush_icache_range((unsigned long) result,
				   (unsigned long) result + len);

#ifdef DEBUG
	printk("do_mmap:\n");
	show_process_blocks();
#endif

	return (unsigned long) result;

 error:
	up_write(&nommu_vma_sem);
	kfree(vml);
	if (vma) {
971 972
		if (vma->vm_file)
			fput(vma->vm_file);
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		kfree(vma);
	}
	return ret;

 sharing_violation:
	up_write(&nommu_vma_sem);
	printk("Attempt to share mismatched mappings\n");
	kfree(vml);
	return -EINVAL;

 error_getting_vma:
	up_write(&nommu_vma_sem);
	kfree(vml);
986
	printk("Allocation of vma for %lu byte allocation from process %d failed\n",
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	       len, current->pid);
	show_free_areas();
	return -ENOMEM;

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

/*
 * handle mapping disposal for uClinux
 */
static void put_vma(struct vm_area_struct *vma)
{
	if (vma) {
		down_write(&nommu_vma_sem);

		if (atomic_dec_and_test(&vma->vm_usage)) {
			delete_nommu_vma(vma);

			if (vma->vm_ops && vma->vm_ops->close)
				vma->vm_ops->close(vma);

			/* IO memory and memory shared directly out of the pagecache from
			 * ramfs/tmpfs mustn't be released here */
			if (vma->vm_flags & VM_MAPPED_COPY) {
				realalloc -= kobjsize((void *) vma->vm_start);
				askedalloc -= vma->vm_end - vma->vm_start;
				kfree((void *) vma->vm_start);
			}

			realalloc -= kobjsize(vma);
			askedalloc -= sizeof(*vma);

			if (vma->vm_file)
				fput(vma->vm_file);
			kfree(vma);
		}

		up_write(&nommu_vma_sem);
	}
}

1032 1033 1034 1035 1036
/*
 * release a mapping
 * - under NOMMU conditions the parameters must match exactly to the mapping to
 *   be removed
 */
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int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
{
	struct vm_list_struct *vml, **parent;
	unsigned long end = addr + len;

#ifdef DEBUG
	printk("do_munmap:\n");
#endif

1046 1047 1048
	for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
		if ((*parent)->vma->vm_start > addr)
			break;
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		if ((*parent)->vma->vm_start == addr &&
1050
		    ((len == 0) || ((*parent)->vma->vm_end == end)))
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			goto found;
1052
	}
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	printk("munmap of non-mmaped memory by process %d (%s): %p\n",
	       current->pid, current->comm, (void *) addr);
	return -EINVAL;

 found:
	vml = *parent;

	put_vma(vml->vma);

	*parent = vml->next;
	realalloc -= kobjsize(vml);
	askedalloc -= sizeof(*vml);
	kfree(vml);
1067 1068

	update_hiwater_vm(mm);
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	mm->total_vm -= len >> PAGE_SHIFT;

#ifdef DEBUG
	show_process_blocks();
#endif

	return 0;
}

1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091
asmlinkage long sys_munmap(unsigned long addr, size_t len)
{
	int ret;
	struct mm_struct *mm = current->mm;

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

/*
 * Release all mappings
 */
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void exit_mmap(struct mm_struct * mm)
{
	struct vm_list_struct *tmp;

	if (mm) {
#ifdef DEBUG
		printk("Exit_mmap:\n");
#endif

		mm->total_vm = 0;

		while ((tmp = mm->context.vmlist)) {
			mm->context.vmlist = tmp->next;
			put_vma(tmp->vma);

			realalloc -= kobjsize(tmp);
			askedalloc -= sizeof(*tmp);
			kfree(tmp);
		}

#ifdef DEBUG
		show_process_blocks();
#endif
	}
}

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

/*
1124 1125
 * expand (or shrink) an existing mapping, potentially moving it at the same
 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
L
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 *
1127 1128 1129
 * under NOMMU conditions, we only permit changing a mapping's size, and only
 * as long as it stays within the hole allocated by the kmalloc() call in
 * do_mmap_pgoff() and the block is not shareable
L
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 *
1131
 * MREMAP_FIXED is not supported under NOMMU conditions
L
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 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
1137
	struct vm_area_struct *vma;
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	/* insanity checks first */
	if (new_len == 0)
		return (unsigned long) -EINVAL;

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

1146 1147 1148
	vma = find_vma_exact(current->mm, addr);
	if (!vma)
		return (unsigned long) -EINVAL;
L
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1150
	if (vma->vm_end != vma->vm_start + old_len)
L
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1151 1152
		return (unsigned long) -EFAULT;

1153
	if (vma->vm_flags & VM_MAYSHARE)
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		return (unsigned long) -EPERM;

	if (new_len > kobjsize((void *) addr))
		return (unsigned long) -ENOMEM;

	/* all checks complete - do it */
1160
	vma->vm_end = vma->vm_start + new_len;
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	askedalloc -= old_len;
	askedalloc += new_len;

1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177
	return vma->vm_start;
}

asmlinkage unsigned long sys_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;
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}

1180
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1181
			unsigned int foll_flags)
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{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
		unsigned long to, unsigned long size, pgprot_t prot)
{
1189 1190
	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
	return 0;
L
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}
1192
EXPORT_SYMBOL(remap_pfn_range);
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1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203

void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
{
}

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

1204
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
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{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
1213
EXPORT_SYMBOL(unmap_mapping_range);
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1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236
/*
 * ask for an unmapped area at which to create a mapping on a file
 */
unsigned long get_unmapped_area(struct file *file, unsigned long addr,
				unsigned long len, unsigned long pgoff,
				unsigned long flags)
{
	unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
				  unsigned long, unsigned long);

	get_area = current->mm->get_unmapped_area;
	if (file && file->f_op && file->f_op->get_unmapped_area)
		get_area = file->f_op->get_unmapped_area;

	if (!get_area)
		return -ENOSYS;

	return get_area(file, addr, len, pgoff, flags);
}

EXPORT_SYMBOL(get_unmapped_area);

L
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1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267
/*
 * 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(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) {
		unsigned long n;

1268
		free = global_page_state(NR_FILE_PAGES);
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		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
		 */
1277
		free += global_page_state(NR_SLAB_RECLAIMABLE);
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		/*
		 * Leave the last 3% for root
		 */
		if (!cap_sys_admin)
			free -= free / 32;

		if (free > pages)
			return 0;

		/*
		 * nr_free_pages() is very expensive on large systems,
		 * only call if we're about to fail.
		 */
		n = nr_free_pages();
1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304

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

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

		if (free > pages)
			return 0;
1311 1312

		goto error;
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	}

	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 */
	allowed -= current->mm->total_vm / 32;

1327 1328 1329 1330 1331
	/*
	 * cast `allowed' as a signed long because vm_committed_space
	 * sometimes has a negative value
	 */
	if (atomic_read(&vm_committed_space) < (long)allowed)
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		return 0;
1333
error:
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	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}
1343

1344
struct page *filemap_fault(struct vm_area_struct *vma, struct fault_data *fdata)
1345 1346 1347 1348
{
	BUG();
	return NULL;
}
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/*
 * Access another process' address space.
 * - source/target buffer must be kernel space
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm;

	if (addr + len < addr)
		return 0;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	down_read(&mm->mmap_sem);

	/* the access must start within one of the target process's mappings */
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	vma = find_vma(mm, addr);
	if (vma) {
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		/* 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 */
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		if (write && vma->vm_flags & VM_MAYWRITE)
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			len -= copy_to_user((void *) addr, buf, len);
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		else if (!write && vma->vm_flags & VM_MAYREAD)
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			len -= copy_from_user(buf, (void *) addr, len);
		else
			len = 0;
	} else {
		len = 0;
	}

	up_read(&mm->mmap_sem);
	mmput(mm);
	return len;
}