nommu.c 46.3 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
 *
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 *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
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 *  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>
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 *  Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org>
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 */

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#include <linux/module.h>
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#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>
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#include <linux/tracehook.h>
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#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>
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#include "internal.h"

static inline __attribute__((format(printf, 1, 2)))
void no_printk(const char *fmt, ...)
{
}

#if 0
#define kenter(FMT, ...) \
	printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
	printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) \
	printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
#else
#define kenter(FMT, ...) \
	no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
#define kleave(FMT, ...) \
	no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
#define kdebug(FMT, ...) \
	no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
#endif
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void *high_memory;
struct page *mem_map;
unsigned long max_mapnr;
unsigned long num_physpages;
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struct percpu_counter vm_committed_as;
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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;
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int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
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int heap_stack_gap = 0;

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atomic_long_t mmap_pages_allocated;
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EXPORT_SYMBOL(mem_map);
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EXPORT_SYMBOL(num_physpages);
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/* list of mapped, potentially shareable regions */
static struct kmem_cache *vm_region_jar;
struct rb_root nommu_region_tree = RB_ROOT;
DECLARE_RWSEM(nommu_region_sem);
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struct vm_operations_struct generic_file_vm_ops = {
};

/*
 * 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:
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	if (inode->i_op->truncate)
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		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;

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	/*
	 * If the object we have should not have ksize performed on it,
	 * return size of 0
	 */
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	if (!objp || !virt_addr_valid(objp))
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		return 0;

	page = virt_to_head_page(objp);

	/*
	 * If the allocator sets PageSlab, we know the pointer came from
	 * kmalloc().
	 */
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	if (PageSlab(page))
		return ksize(objp);

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	/*
	 * If it's not a compound page, see if we have a matching VMA
	 * region. This test is intentionally done in reverse order,
	 * so if there's no VMA, we still fall through and hand back
	 * PAGE_SIZE for 0-order pages.
	 */
	if (!PageCompound(page)) {
		struct vm_area_struct *vma;

		vma = find_vma(current->mm, (unsigned long)objp);
		if (vma)
			return vma->vm_end - vma->vm_start;
	}

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	/*
	 * The ksize() function is only guaranteed to work for pointers
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	 * returned by kmalloc(). So handle arbitrary pointers here.
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	 */
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	return PAGE_SIZE << compound_order(page);
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}

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int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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		     unsigned long start, int nr_pages, int foll_flags,
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		     struct page **pages, struct vm_area_struct **vmas)
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{
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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.
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	 * If FOLL_FORCE is set, we only require the "MAY" flags.
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	 */
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	vm_flags  = (foll_flags & FOLL_WRITE) ?
			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= (foll_flags & FOLL_FORCE) ?
			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
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	for (i = 0; i < nr_pages; 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 */
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		if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
		    !(vm_flags & vma->vm_flags))
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			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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/*
 * 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
 */
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
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	unsigned long start, int nr_pages, int write, int force,
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	struct page **pages, struct vm_area_struct **vmas)
{
	int flags = 0;

	if (write)
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		flags |= FOLL_WRITE;
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	if (force)
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		flags |= FOLL_FORCE;
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	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas);
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}
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EXPORT_SYMBOL(get_user_pages);

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/**
 * follow_pfn - look up PFN at a user virtual address
 * @vma: memory mapping
 * @address: user virtual address
 * @pfn: location to store found PFN
 *
 * Only IO mappings and raw PFN mappings are allowed.
 *
 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 */
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
	unsigned long *pfn)
{
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		return -EINVAL;

	*pfn = address >> PAGE_SHIFT;
	return 0;
}
EXPORT_SYMBOL(follow_pfn);

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DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;

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void vfree(const void *addr)
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{
	kfree(addr);
}
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EXPORT_SYMBOL(vfree);
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void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
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{
	/*
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	 *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
	 * returns only a logical address.
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	 */
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	return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
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}
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EXPORT_SYMBOL(__vmalloc);
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void *vmalloc_user(unsigned long size)
{
	void *ret;

	ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
			PAGE_KERNEL);
	if (ret) {
		struct vm_area_struct *vma;

		down_write(&current->mm->mmap_sem);
		vma = find_vma(current->mm, (unsigned long)ret);
		if (vma)
			vma->vm_flags |= VM_USERMAP;
		up_write(&current->mm->mmap_sem);
	}

	return ret;
}
EXPORT_SYMBOL(vmalloc_user);

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struct page *vmalloc_to_page(const void *addr)
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{
	return virt_to_page(addr);
}
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EXPORT_SYMBOL(vmalloc_to_page);
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unsigned long vmalloc_to_pfn(const void *addr)
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{
	return page_to_pfn(virt_to_page(addr));
}
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EXPORT_SYMBOL(vmalloc_to_pfn);
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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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#ifndef PAGE_KERNEL_EXEC
# define PAGE_KERNEL_EXEC PAGE_KERNEL
#endif

/**
 *	vmalloc_exec  -  allocate virtually contiguous, executable memory
 *	@size:		allocation size
 *
 *	Kernel-internal function to allocate enough pages to cover @size
 *	the page level allocator and map them into contiguous and
 *	executable kernel virtual space.
 *
 *	For tight control over page level allocator and protection flags
 *	use __vmalloc() instead.
 */

void *vmalloc_exec(unsigned long size)
{
	return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
}

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/**
 * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
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 *	@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);
}
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EXPORT_SYMBOL(vmalloc_32);

/**
 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 *	@size:		allocation size
 *
 * The resulting memory area is 32bit addressable and zeroed so it can be
 * mapped to userspace without leaking data.
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 *
 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 * remap_vmalloc_range() are permissible.
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 */
void *vmalloc_32_user(unsigned long size)
{
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	/*
	 * We'll have to sort out the ZONE_DMA bits for 64-bit,
	 * but for now this can simply use vmalloc_user() directly.
	 */
	return vmalloc_user(size);
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}
EXPORT_SYMBOL(vmalloc_32_user);
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void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
{
	BUG();
	return NULL;
}
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EXPORT_SYMBOL(vmap);
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void vunmap(const void *addr)
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{
	BUG();
}
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EXPORT_SYMBOL(vunmap);
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void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
{
	BUG();
	return NULL;
}
EXPORT_SYMBOL(vm_map_ram);

void vm_unmap_ram(const void *mem, unsigned int count)
{
	BUG();
}
EXPORT_SYMBOL(vm_unmap_ram);

void vm_unmap_aliases(void)
{
}
EXPORT_SYMBOL_GPL(vm_unmap_aliases);

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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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int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
		   struct page *page)
{
	return -EINVAL;
}
EXPORT_SYMBOL(vm_insert_page);

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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.
 */
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SYSCALL_DEFINE1(brk, unsigned long, brk)
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{
	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;
}

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/*
 * initialise the VMA and region record slabs
 */
void __init mmap_init(void)
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{
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	int ret;

	ret = percpu_counter_init(&vm_committed_as, 0);
	VM_BUG_ON(ret);
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	vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
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}

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/*
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 * validate the region tree
 * - the caller must hold the region lock
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 */
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#ifdef CONFIG_DEBUG_NOMMU_REGIONS
static noinline void validate_nommu_regions(void)
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{
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	struct vm_region *region, *last;
	struct rb_node *p, *lastp;
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	lastp = rb_first(&nommu_region_tree);
	if (!lastp)
		return;

	last = rb_entry(lastp, struct vm_region, vm_rb);
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	BUG_ON(unlikely(last->vm_end <= last->vm_start));
	BUG_ON(unlikely(last->vm_top < last->vm_end));
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	while ((p = rb_next(lastp))) {
		region = rb_entry(p, struct vm_region, vm_rb);
		last = rb_entry(lastp, struct vm_region, vm_rb);

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		BUG_ON(unlikely(region->vm_end <= region->vm_start));
		BUG_ON(unlikely(region->vm_top < region->vm_end));
		BUG_ON(unlikely(region->vm_start < last->vm_top));
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		lastp = p;
	}
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}
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#else
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static void validate_nommu_regions(void)
{
}
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#endif
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/*
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 * add a region into the global tree
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 */
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static void add_nommu_region(struct vm_region *region)
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{
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	struct vm_region *pregion;
	struct rb_node **p, *parent;
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	validate_nommu_regions();

	parent = NULL;
	p = &nommu_region_tree.rb_node;
	while (*p) {
		parent = *p;
		pregion = rb_entry(parent, struct vm_region, vm_rb);
		if (region->vm_start < pregion->vm_start)
			p = &(*p)->rb_left;
		else if (region->vm_start > pregion->vm_start)
			p = &(*p)->rb_right;
		else if (pregion == region)
			return;
		else
			BUG();
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	}

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	rb_link_node(&region->vm_rb, parent, p);
	rb_insert_color(&region->vm_rb, &nommu_region_tree);
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	validate_nommu_regions();
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}

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/*
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 * delete a region from the global tree
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 */
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static void delete_nommu_region(struct vm_region *region)
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{
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	BUG_ON(!nommu_region_tree.rb_node);
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	validate_nommu_regions();
	rb_erase(&region->vm_rb, &nommu_region_tree);
	validate_nommu_regions();
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}

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/*
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 * free a contiguous series of pages
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 */
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static void free_page_series(unsigned long from, unsigned long to)
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{
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	for (; from < to; from += PAGE_SIZE) {
		struct page *page = virt_to_page(from);

		kdebug("- free %lx", from);
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		atomic_long_dec(&mmap_pages_allocated);
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		if (page_count(page) != 1)
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			kdebug("free page %p: refcount not one: %d",
			       page, page_count(page));
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		put_page(page);
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	}
}

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/*
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 * release a reference to a region
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 * - the caller must hold the region semaphore for writing, which this releases
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 * - the region may not have been added to the tree yet, in which case vm_top
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 *   will equal vm_start
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 */
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static void __put_nommu_region(struct vm_region *region)
	__releases(nommu_region_sem)
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{
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	kenter("%p{%d}", region, atomic_read(&region->vm_usage));
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	BUG_ON(!nommu_region_tree.rb_node);
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	if (atomic_dec_and_test(&region->vm_usage)) {
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		if (region->vm_top > region->vm_start)
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			delete_nommu_region(region);
		up_write(&nommu_region_sem);

		if (region->vm_file)
			fput(region->vm_file);

		/* IO memory and memory shared directly out of the pagecache
		 * from ramfs/tmpfs mustn't be released here */
		if (region->vm_flags & VM_MAPPED_COPY) {
			kdebug("free series");
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			free_page_series(region->vm_start, region->vm_top);
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		}
		kmem_cache_free(vm_region_jar, region);
	} else {
		up_write(&nommu_region_sem);
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	}
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}
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/*
 * release a reference to a region
 */
static void put_nommu_region(struct vm_region *region)
{
	down_write(&nommu_region_sem);
	__put_nommu_region(region);
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}

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/*
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 * add a VMA into a process's mm_struct in the appropriate place in the list
 * and tree and add to the address space's page tree also if not an anonymous
 * page
 * - should be called with mm->mmap_sem held writelocked
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 */
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static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
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{
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	struct vm_area_struct *pvma, **pp;
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	struct address_space *mapping;
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	struct rb_node **p, *parent;

	kenter(",%p", vma);

	BUG_ON(!vma->vm_region);

	mm->map_count++;
	vma->vm_mm = mm;
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	/* 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);
	}

653 654 655
	/* add the VMA to the tree */
	parent = NULL;
	p = &mm->mm_rb.rb_node;
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	while (*p) {
		parent = *p;
		pvma = rb_entry(parent, struct vm_area_struct, vm_rb);

660 661 662
		/* sort by: start addr, end addr, VMA struct addr in that order
		 * (the latter is necessary as we may get identical VMAs) */
		if (vma->vm_start < pvma->vm_start)
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			p = &(*p)->rb_left;
664
		else if (vma->vm_start > pvma->vm_start)
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			p = &(*p)->rb_right;
666 667 668 669 670 671 672 673 674 675
		else if (vma->vm_end < pvma->vm_end)
			p = &(*p)->rb_left;
		else if (vma->vm_end > pvma->vm_end)
			p = &(*p)->rb_right;
		else if (vma < pvma)
			p = &(*p)->rb_left;
		else if (vma > pvma)
			p = &(*p)->rb_right;
		else
			BUG();
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	}

	rb_link_node(&vma->vm_rb, parent, p);
679 680 681 682 683 684 685 686 687 688 689 690 691 692
	rb_insert_color(&vma->vm_rb, &mm->mm_rb);

	/* add VMA to the VMA list also */
	for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) {
		if (pvma->vm_start > vma->vm_start)
			break;
		if (pvma->vm_start < vma->vm_start)
			continue;
		if (pvma->vm_end < vma->vm_end)
			break;
	}

	vma->vm_next = *pp;
	*pp = vma;
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}

695
/*
696
 * delete a VMA from its owning mm_struct and address space
697
 */
698
static void delete_vma_from_mm(struct vm_area_struct *vma)
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{
700
	struct vm_area_struct **pp;
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	struct address_space *mapping;
702 703 704 705 706 707 708
	struct mm_struct *mm = vma->vm_mm;

	kenter("%p", vma);

	mm->map_count--;
	if (mm->mmap_cache == vma)
		mm->mmap_cache = NULL;
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	/* 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);
	}

719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827
	/* remove from the MM's tree and list */
	rb_erase(&vma->vm_rb, &mm->mm_rb);
	for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) {
		if (*pp == vma) {
			*pp = vma->vm_next;
			break;
		}
	}

	vma->vm_mm = NULL;
}

/*
 * destroy a VMA record
 */
static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
{
	kenter("%p", vma);
	if (vma->vm_ops && vma->vm_ops->close)
		vma->vm_ops->close(vma);
	if (vma->vm_file) {
		fput(vma->vm_file);
		if (vma->vm_flags & VM_EXECUTABLE)
			removed_exe_file_vma(mm);
	}
	put_nommu_region(vma->vm_region);
	kmem_cache_free(vm_area_cachep, vma);
}

/*
 * 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_area_struct *vma;
	struct rb_node *n = mm->mm_rb.rb_node;

	/* check the cache first */
	vma = mm->mmap_cache;
	if (vma && vma->vm_start <= addr && vma->vm_end > addr)
		return vma;

	/* trawl the tree (there may be multiple mappings in which addr
	 * resides) */
	for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
		vma = rb_entry(n, struct vm_area_struct, vm_rb);
		if (vma->vm_start > addr)
			return NULL;
		if (vma->vm_end > addr) {
			mm->mmap_cache = vma;
			return vma;
		}
	}

	return NULL;
}
EXPORT_SYMBOL(find_vma);

/*
 * 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);
}

/*
 * expand a stack to a given address
 * - not supported under NOMMU conditions
 */
int expand_stack(struct vm_area_struct *vma, unsigned long address)
{
	return -ENOMEM;
}

/*
 * look up the first VMA exactly that exactly matches addr
 * - should be called with mm->mmap_sem at least held readlocked
 */
static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
					     unsigned long addr,
					     unsigned long len)
{
	struct vm_area_struct *vma;
	struct rb_node *n = mm->mm_rb.rb_node;
	unsigned long end = addr + len;

	/* check the cache first */
	vma = mm->mmap_cache;
	if (vma && vma->vm_start == addr && vma->vm_end == end)
		return vma;

	/* trawl the tree (there may be multiple mappings in which addr
	 * resides) */
	for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) {
		vma = rb_entry(n, struct vm_area_struct, vm_rb);
		if (vma->vm_start < addr)
			continue;
		if (vma->vm_start > addr)
			return NULL;
		if (vma->vm_end == end) {
			mm->mmap_cache = vma;
			return vma;
		}
	}

	return NULL;
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}

/*
 * 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)
{
842
	unsigned long capabilities, rlen;
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	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;

858
	if (!len)
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		return -EINVAL;

861
	/* Careful about overflows.. */
862 863
	rlen = PAGE_ALIGN(len);
	if (!rlen || rlen > TASK_SIZE)
864 865
		return -ENOMEM;

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	/* offset overflow? */
867
	if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
868
		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;

918 919 920 921
		/* The file shall have been opened with read permission. */
		if (!(file->f_mode & FMODE_READ))
			return -EACCES;

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		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 */
995
	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
	 */
1038
	if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
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		vm_flags &= ~VM_MAYSHARE;

	return vm_flags;
}

/*
1045 1046
 * set up a shared mapping on a file (the driver or filesystem provides and
 * pins the storage)
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 */
1048
static int do_mmap_shared_file(struct vm_area_struct *vma)
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{
	int ret;

	ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1053 1054 1055 1056
	if (ret == 0) {
		vma->vm_region->vm_top = vma->vm_region->vm_end;
		return ret;
	}
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	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
 */
1070 1071 1072
static int do_mmap_private(struct vm_area_struct *vma,
			   struct vm_region *region,
			   unsigned long len)
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{
1074 1075
	struct page *pages;
	unsigned long total, point, n, rlen;
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	void *base;
1077
	int ret, order;
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	/* 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);
1085
		if (ret == 0) {
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			/* shouldn't return success if we're not sharing */
1087 1088 1089
			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
			vma->vm_region->vm_top = vma->vm_region->vm_end;
			return ret;
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		}
1091 1092
		if (ret != -ENOSYS)
			return ret;
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		/* 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 */
	}

1099 1100
	rlen = PAGE_ALIGN(len);

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	/* 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
	 */
1105 1106 1107 1108 1109
	order = get_order(rlen);
	kdebug("alloc order %d for %lx", order, len);

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

1112
	total = 1 << order;
1113
	atomic_long_add(total, &mmap_pages_allocated);
1114 1115

	point = rlen >> PAGE_SHIFT;
1116 1117 1118 1119 1120 1121 1122 1123

	/* 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);
1124
			atomic_long_sub(n, &mmap_pages_allocated);
1125 1126 1127 1128
			total -= n;
			set_page_refcounted(pages + total);
			__free_pages(pages + total, order);
		}
1129 1130 1131 1132
	}

	for (point = 1; point < total; point++)
		set_page_refcounted(&pages[point]);
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1134 1135 1136 1137
	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 + rlen;
1138
	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1139 1140 1141

	vma->vm_start = region->vm_start;
	vma->vm_end   = region->vm_start + len;
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	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);
1153
		ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos);
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		set_fs(old_fs);

		if (ret < 0)
			goto error_free;

		/* clear the last little bit */
1160 1161
		if (ret < rlen)
			memset(base + ret, 0, rlen - ret);
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	} else {
		/* if it's an anonymous mapping, then just clear it */
1165
		memset(base, 0, rlen);
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	}

	return 0;

error_free:
1171 1172 1173
	free_page_series(region->vm_start, region->vm_end);
	region->vm_start = vma->vm_start = 0;
	region->vm_end   = vma->vm_end = 0;
1174
	region->vm_top   = 0;
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	return ret;

enomem:
1178 1179
	printk("Allocation of length %lu from process %d (%s) failed\n",
	       len, current->pid, current->comm);
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	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)
{
1194 1195
	struct vm_area_struct *vma;
	struct vm_region *region;
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	struct rb_node *rb;
1197
	unsigned long capabilities, vm_flags, result;
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	int ret;

1200 1201
	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);

1202 1203 1204
	if (!(flags & MAP_FIXED))
		addr = round_hint_to_min(addr);

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	/* 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);
1209 1210
	if (ret < 0) {
		kleave(" = %d [val]", ret);
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		return ret;
1212
	}
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	/* 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);

1218 1219 1220 1221 1222 1223 1224 1225
	/* 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;
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1227 1228 1229 1230 1231 1232 1233
	atomic_set(&region->vm_usage, 1);
	region->vm_flags = vm_flags;
	region->vm_pgoff = pgoff;

	INIT_LIST_HEAD(&vma->anon_vma_node);
	vma->vm_flags = vm_flags;
	vma->vm_pgoff = pgoff;
L
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1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
	if (file) {
		region->vm_file = file;
		get_file(file);
		vma->vm_file = file;
		get_file(file);
		if (vm_flags & VM_EXECUTABLE) {
			added_exe_file_vma(current->mm);
			vma->vm_mm = current->mm;
		}
	}

	down_write(&nommu_region_sem);

	/* if we want to share, we need to check for regions created by other
L
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1249
	 * mmap() calls that overlap with our proposed mapping
1250
	 * - we can only share with a superset match on most regular files
L
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1251 1252 1253 1254 1255 1256
	 * - 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) {
1257 1258
		struct vm_region *pregion;
		unsigned long pglen, rpglen, pgend, rpgend, start;
L
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1259

1260 1261
		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		pgend = pgoff + pglen;
1262

1263 1264
		for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
			pregion = rb_entry(rb, struct vm_region, vm_rb);
L
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1266
			if (!(pregion->vm_flags & VM_MAYSHARE))
L
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1267 1268 1269
				continue;

			/* search for overlapping mappings on the same file */
1270 1271
			if (pregion->vm_file->f_path.dentry->d_inode !=
			    file->f_path.dentry->d_inode)
L
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1272 1273
				continue;

1274
			if (pregion->vm_pgoff >= pgend)
L
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				continue;

1277 1278 1279 1280
			rpglen = pregion->vm_end - pregion->vm_start;
			rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
			rpgend = pregion->vm_pgoff + rpglen;
			if (pgoff >= rpgend)
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				continue;

1283 1284 1285 1286 1287
			/* 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 */
L
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1288 1289 1290 1291 1292
				if (!(capabilities & BDI_CAP_MAP_DIRECT))
					goto sharing_violation;
				continue;
			}

1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320
			/* we've found a region we can share */
			atomic_inc(&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;
					atomic_dec(&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;
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		}

		/* 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)
1333
					goto error_just_free;
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				/* 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))
1340
					goto error_just_free;
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				capabilities &= ~BDI_CAP_MAP_DIRECT;
1343 1344 1345
			} else {
				vma->vm_start = region->vm_start = addr;
				vma->vm_end = region->vm_end = addr + len;
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			}
		}
	}

1350
	vma->vm_region = region;
1351
	add_nommu_region(region);
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	/* set up the mapping */
	if (file && vma->vm_flags & VM_SHARED)
1355
		ret = do_mmap_shared_file(vma);
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	else
1357
		ret = do_mmap_private(vma, region, len);
L
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1358
	if (ret < 0)
1359 1360
		goto error_put_region;

L
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1361
	/* okay... we have a mapping; now we have to register it */
1362
	result = vma->vm_start;
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	current->mm->total_vm += len >> PAGE_SHIFT;

1366 1367
share:
	add_vma_to_mm(current->mm, vma);
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1368

1369
	up_write(&nommu_region_sem);
L
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	if (prot & PROT_EXEC)
1372
		flush_icache_range(result, result + len);
L
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1373

1374 1375
	kleave(" = %lx", result);
	return result;
L
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1377 1378
error_put_region:
	__put_nommu_region(region);
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	if (vma) {
M
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		if (vma->vm_file) {
1381
			fput(vma->vm_file);
M
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1382 1383 1384
			if (vma->vm_flags & VM_EXECUTABLE)
				removed_exe_file_vma(vma->vm_mm);
		}
1385
		kmem_cache_free(vm_area_cachep, vma);
L
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1386
	}
1387
	kleave(" = %d [pr]", ret);
L
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1388 1389
	return ret;

1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406
error_just_free:
	up_write(&nommu_region_sem);
error:
	fput(region->vm_file);
	kmem_cache_free(vm_region_jar, region);
	fput(vma->vm_file);
	if (vma->vm_flags & VM_EXECUTABLE)
		removed_exe_file_vma(vma->vm_mm);
	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;
L
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1408 1409 1410 1411
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",
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1412 1413 1414 1415
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;

1416 1417 1418
error_getting_region:
	printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
	       " from process %d failed\n",
L
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1419 1420 1421 1422
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;
}
1423
EXPORT_SYMBOL(do_mmap_pgoff);
L
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1424 1425

/*
1426 1427
 * split a vma into two pieces at address 'addr', a new vma is allocated either
 * for the first part or the tail.
L
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1428
 */
1429 1430
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
	      unsigned long addr, int new_below)
L
Linus Torvalds 已提交
1431
{
1432 1433 1434
	struct vm_area_struct *new;
	struct vm_region *region;
	unsigned long npages;
L
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1435

1436
	kenter("");
L
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1437

1438 1439 1440 1441 1442
	/* we're only permitted to split anonymous regions that have a single
	 * owner */
	if (vma->vm_file ||
	    atomic_read(&vma->vm_region->vm_usage) != 1)
		return -ENOMEM;
L
Linus Torvalds 已提交
1443

1444 1445
	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;
L
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1446

1447 1448 1449
	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		return -ENOMEM;
L
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1450

1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464
	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) {
1465
		region->vm_top = region->vm_end = new->vm_end = addr;
1466 1467 1468
	} else {
		region->vm_start = new->vm_start = addr;
		region->vm_pgoff = new->vm_pgoff += npages;
L
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1469
	}
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481

	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;
1482
		vma->vm_region->vm_top = addr;
1483 1484 1485 1486 1487 1488 1489
	}
	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;
L
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1490 1491
}

1492
/*
1493 1494
 * shrink a VMA by removing the specified chunk from either the beginning or
 * the end
1495
 */
1496 1497 1498
static int shrink_vma(struct mm_struct *mm,
		      struct vm_area_struct *vma,
		      unsigned long from, unsigned long to)
L
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1499
{
1500
	struct vm_region *region;
L
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1501

1502
	kenter("");
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1504 1505 1506 1507 1508 1509 1510 1511
	/* 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);
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1513 1514 1515 1516 1517 1518
	/* cut the backing region down to size */
	region = vma->vm_region;
	BUG_ON(atomic_read(&region->vm_usage) != 1);

	down_write(&nommu_region_sem);
	delete_nommu_region(region);
1519 1520 1521 1522
	if (from > region->vm_start) {
		to = region->vm_top;
		region->vm_top = region->vm_end = from;
	} else {
1523
		region->vm_start = to;
1524
	}
1525 1526 1527 1528 1529 1530
	add_nommu_region(region);
	up_write(&nommu_region_sem);

	free_page_series(from, to);
	return 0;
}
L
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1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542
/*
 * 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;
	struct rb_node *rb;
	unsigned long end = start + len;
	int ret;
L
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1543

1544
	kenter(",%lx,%zx", start, len);
L
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1545

1546 1547
	if (len == 0)
		return -EINVAL;
1548

1549 1550 1551
	/* find the first potentially overlapping VMA */
	vma = find_vma(mm, start);
	if (!vma) {
1552 1553 1554 1555 1556 1557 1558 1559 1560
		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++;
		}
1561 1562
		return -EINVAL;
	}
L
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1563

1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602
	/* 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;
			rb = rb_next(&vma->vm_rb);
			vma = rb_entry(rb, struct vm_area_struct, vm_rb);
		} while (rb);
		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);
	}
L
Linus Torvalds 已提交
1603

1604 1605 1606 1607
erase_whole_vma:
	delete_vma_from_mm(vma);
	delete_vma(mm, vma);
	kleave(" = 0");
L
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1608 1609
	return 0;
}
1610
EXPORT_SYMBOL(do_munmap);
L
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1611

1612
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623
{
	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;
}

/*
1624
 * release all the mappings made in a process's VM space
1625
 */
1626
void exit_mmap(struct mm_struct *mm)
L
Linus Torvalds 已提交
1627
{
1628
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1629

1630 1631
	if (!mm)
		return;
L
Linus Torvalds 已提交
1632

1633
	kenter("");
L
Linus Torvalds 已提交
1634

1635
	mm->total_vm = 0;
L
Linus Torvalds 已提交
1636

1637 1638 1639 1640
	while ((vma = mm->mmap)) {
		mm->mmap = vma->vm_next;
		delete_vma_from_mm(vma);
		delete_vma(mm, vma);
L
Linus Torvalds 已提交
1641
	}
1642 1643

	kleave("");
L
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1644 1645 1646 1647 1648 1649 1650 1651
}

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

/*
1652 1653
 * expand (or shrink) an existing mapping, potentially moving it at the same
 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
L
Linus Torvalds 已提交
1654
 *
1655
 * under NOMMU conditions, we only permit changing a mapping's size, and only
1656 1657
 * as long as it stays within the region allocated by do_mmap_private() and the
 * block is not shareable
L
Linus Torvalds 已提交
1658
 *
1659
 * MREMAP_FIXED is not supported under NOMMU conditions
L
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1660 1661 1662 1663 1664
 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
1665
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1666 1667

	/* insanity checks first */
1668
	if (old_len == 0 || new_len == 0)
L
Linus Torvalds 已提交
1669 1670
		return (unsigned long) -EINVAL;

1671 1672 1673
	if (addr & ~PAGE_MASK)
		return -EINVAL;

L
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1674 1675 1676
	if (flags & MREMAP_FIXED && new_addr != addr)
		return (unsigned long) -EINVAL;

1677
	vma = find_vma_exact(current->mm, addr, old_len);
1678 1679
	if (!vma)
		return (unsigned long) -EINVAL;
L
Linus Torvalds 已提交
1680

1681
	if (vma->vm_end != vma->vm_start + old_len)
L
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1682 1683
		return (unsigned long) -EFAULT;

1684
	if (vma->vm_flags & VM_MAYSHARE)
L
Linus Torvalds 已提交
1685 1686
		return (unsigned long) -EPERM;

1687
	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
L
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1688 1689 1690
		return (unsigned long) -ENOMEM;

	/* all checks complete - do it */
1691 1692 1693
	vma->vm_end = vma->vm_start + new_len;
	return vma->vm_start;
}
1694
EXPORT_SYMBOL(do_mremap);
1695

1696 1697 1698
SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
		unsigned long, new_len, unsigned long, flags,
		unsigned long, new_addr)
1699 1700 1701 1702 1703 1704 1705
{
	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;
L
Linus Torvalds 已提交
1706 1707
}

1708
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1709
			unsigned int foll_flags)
L
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1710 1711 1712 1713 1714 1715 1716
{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
		unsigned long to, unsigned long size, pgprot_t prot)
{
1717 1718
	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
	return 0;
L
Linus Torvalds 已提交
1719
}
1720
EXPORT_SYMBOL(remap_pfn_range);
L
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1721

1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736
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);

L
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1737 1738 1739 1740 1741 1742 1743 1744 1745 1746
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;
}

1747
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1748 1749 1750 1751 1752 1753 1754 1755
{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
1756
EXPORT_SYMBOL(unmap_mapping_range);
L
Linus Torvalds 已提交
1757

1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778
/*
 * 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
Linus Torvalds 已提交
1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794
/*
 * 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.
 */
1795
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
L
Linus Torvalds 已提交
1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809
{
	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;

1810
		free = global_page_state(NR_FILE_PAGES);
L
Linus Torvalds 已提交
1811 1812 1813 1814 1815 1816 1817 1818
		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
		 */
1819
		free += global_page_state(NR_SLAB_RECLAIMABLE);
L
Linus Torvalds 已提交
1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834

		/*
		 * 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();
1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846

		/*
		 * 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
		 */
L
Linus Torvalds 已提交
1847 1848 1849 1850 1851 1852
		if (!cap_sys_admin)
			n -= n / 32;
		free += n;

		if (free > pages)
			return 0;
1853 1854

		goto error;
L
Linus Torvalds 已提交
1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866
	}

	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 */
A
Alan Cox 已提交
1867 1868
	if (mm)
		allowed -= mm->total_vm / 32;
L
Linus Torvalds 已提交
1869

1870
	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
L
Linus Torvalds 已提交
1871
		return 0;
1872

1873
error:
L
Linus Torvalds 已提交
1874 1875 1876 1877 1878 1879 1880 1881 1882
	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}
1883

N
Nick Piggin 已提交
1884
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1885 1886
{
	BUG();
N
Nick Piggin 已提交
1887
	return 0;
1888
}
1889
EXPORT_SYMBOL(filemap_fault);
1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909

/*
 * 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 */
1910 1911
	vma = find_vma(mm, addr);
	if (vma) {
1912 1913 1914 1915 1916
		/* 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 */
1917
		if (write && vma->vm_flags & VM_MAYWRITE)
1918
			len -= copy_to_user((void *) addr, buf, len);
1919
		else if (!write && vma->vm_flags & VM_MAYREAD)
1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930
			len -= copy_from_user(buf, (void *) addr, len);
		else
			len = 0;
	} else {
		len = 0;
	}

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