nommu.c 47.8 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 <asm/mmu_context.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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unsigned long highest_memmap_pfn;
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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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const struct vm_operations_struct generic_file_vm_ops = {
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};

/*
 * 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, unsigned 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_extend_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.
	 */
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	flush_icache_range(mm->brk, brk);
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	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, region->vm_usage);
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	BUG_ON(!nommu_region_tree.rb_node);
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	if (--region->vm_usage == 0) {
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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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/*
 * update protection on a vma
 */
static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
{
#ifdef CONFIG_MPU
	struct mm_struct *mm = vma->vm_mm;
	long start = vma->vm_start & PAGE_MASK;
	while (start < vma->vm_end) {
		protect_page(mm, start, flags);
		start += PAGE_SIZE;
	}
	update_protections(mm);
#endif
}

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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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	protect_vma(vma, vma->vm_flags);

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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);
	}

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	/* 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);

641 642 643
		/* 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;
645
		else if (vma->vm_start > pvma->vm_start)
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			p = &(*p)->rb_right;
647 648 649 650 651 652 653 654 655 656
		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);
660 661 662 663 664 665 666 667 668 669 670 671 672 673
	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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}

676
/*
677
 * delete a VMA from its owning mm_struct and address space
678
 */
679
static void delete_vma_from_mm(struct vm_area_struct *vma)
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{
681
	struct vm_area_struct **pp;
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	struct address_space *mapping;
683 684 685 686
	struct mm_struct *mm = vma->vm_mm;

	kenter("%p", vma);

687 688
	protect_vma(vma, 0);

689 690 691
	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);
	}

702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766
	/* 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)
{
767
	return find_vma(mm, addr & PAGE_MASK);
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
}

/*
 * 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)
{
825
	unsigned long capabilities, rlen;
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	unsigned long reqprot = prot;
	int ret;

	/* do the simple checks first */
830
	if (flags & MAP_FIXED) {
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		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;

841
	if (!len)
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		return -EINVAL;

844
	/* Careful about overflows.. */
845 846
	rlen = PAGE_ALIGN(len);
	if (!rlen || rlen > TASK_SIZE)
847 848
		return -ENOMEM;

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	/* offset overflow? */
850
	if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
851
		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;

901 902 903 904
		/* 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 */
978
	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
	 */
1021
	if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
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		vm_flags &= ~VM_MAYSHARE;

	return vm_flags;
}

/*
1028 1029
 * set up a shared mapping on a file (the driver or filesystem provides and
 * pins the storage)
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 */
1031
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);
1036 1037
	if (ret == 0) {
		vma->vm_region->vm_top = vma->vm_region->vm_end;
1038
		return 0;
1039
	}
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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
 */
1053 1054
static int do_mmap_private(struct vm_area_struct *vma,
			   struct vm_region *region,
1055 1056
			   unsigned long len,
			   unsigned long capabilities)
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{
1058 1059
	struct page *pages;
	unsigned long total, point, n, rlen;
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	void *base;
1061
	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
	 */
1067
	if (capabilities & BDI_CAP_MAP_DIRECT) {
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		ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1069
		if (ret == 0) {
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			/* shouldn't return success if we're not sharing */
1071 1072
			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
			vma->vm_region->vm_top = vma->vm_region->vm_end;
1073
			return 0;
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		}
1075 1076
		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 */
	}

1083 1084
	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
	 */
1089 1090 1091 1092 1093
	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;

1096
	total = 1 << order;
1097
	atomic_long_add(total, &mmap_pages_allocated);
1098 1099

	point = rlen >> PAGE_SHIFT;
1100 1101 1102 1103 1104 1105 1106 1107

	/* 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);
1108
			atomic_long_sub(n, &mmap_pages_allocated);
1109 1110 1111 1112
			total -= n;
			set_page_refcounted(pages + total);
			__free_pages(pages + total, order);
		}
1113 1114 1115 1116
	}

	for (point = 1; point < total; point++)
		set_page_refcounted(&pages[point]);
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1118 1119 1120 1121
	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;
1122
	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1123 1124 1125

	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);
1137
		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 */
1144 1145
		if (ret < rlen)
			memset(base + ret, 0, rlen - ret);
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	}

	return 0;

error_free:
1152 1153 1154
	free_page_series(region->vm_start, region->vm_end);
	region->vm_start = vma->vm_start = 0;
	region->vm_end   = vma->vm_end = 0;
1155
	region->vm_top   = 0;
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	return ret;

enomem:
1159 1160
	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)
{
1175 1176
	struct vm_area_struct *vma;
	struct vm_region *region;
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	struct rb_node *rb;
1178
	unsigned long capabilities, vm_flags, result;
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	int ret;

1181 1182
	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);

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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);
1187 1188
	if (ret < 0) {
		kleave(" = %d [val]", ret);
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		return ret;
1190
	}
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1192 1193 1194
	/* we ignore the address hint */
	addr = 0;

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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);

1199 1200 1201 1202 1203 1204 1205 1206
	/* 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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1208
	region->vm_usage = 1;
1209 1210 1211
	region->vm_flags = vm_flags;
	region->vm_pgoff = pgoff;

1212
	INIT_LIST_HEAD(&vma->anon_vma_chain);
1213 1214
	vma->vm_flags = vm_flags;
	vma->vm_pgoff = pgoff;
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1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229
	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
Linus Torvalds 已提交
1230
	 * mmap() calls that overlap with our proposed mapping
1231
	 * - we can only share with a superset match on most regular files
L
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1232 1233 1234 1235 1236 1237
	 * - 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) {
1238 1239
		struct vm_region *pregion;
		unsigned long pglen, rpglen, pgend, rpgend, start;
L
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1241 1242
		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		pgend = pgoff + pglen;
1243

1244 1245
		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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1246

1247
			if (!(pregion->vm_flags & VM_MAYSHARE))
L
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1248 1249 1250
				continue;

			/* search for overlapping mappings on the same file */
1251 1252
			if (pregion->vm_file->f_path.dentry->d_inode !=
			    file->f_path.dentry->d_inode)
L
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1253 1254
				continue;

1255
			if (pregion->vm_pgoff >= pgend)
L
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1256 1257
				continue;

1258 1259 1260 1261
			rpglen = pregion->vm_end - pregion->vm_start;
			rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
			rpgend = pregion->vm_pgoff + rpglen;
			if (pgoff >= rpgend)
L
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1262 1263
				continue;

1264 1265 1266 1267 1268
			/* 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 */
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1269 1270 1271 1272 1273
				if (!(capabilities & BDI_CAP_MAP_DIRECT))
					goto sharing_violation;
				continue;
			}

1274
			/* we've found a region we can share */
1275
			pregion->vm_usage++;
1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291
			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;
1292
					pregion->vm_usage--;
1293 1294 1295 1296 1297 1298 1299 1300 1301
					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
		 */
1308
		if (capabilities & BDI_CAP_MAP_DIRECT) {
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			addr = file->f_op->get_unmapped_area(file, addr, len,
							     pgoff, flags);
			if (IS_ERR((void *) addr)) {
				ret = addr;
				if (ret != (unsigned long) -ENOSYS)
1314
					goto error_just_free;
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1315 1316 1317 1318 1319 1320

				/* 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))
1321
					goto error_just_free;
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1322 1323

				capabilities &= ~BDI_CAP_MAP_DIRECT;
1324 1325 1326
			} else {
				vma->vm_start = region->vm_start = addr;
				vma->vm_end = region->vm_end = addr + len;
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			}
		}
	}

1331
	vma->vm_region = region;
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1333 1334 1335
	/* set up the mapping
	 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
	 */
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	if (file && vma->vm_flags & VM_SHARED)
1337
		ret = do_mmap_shared_file(vma);
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1338
	else
1339
		ret = do_mmap_private(vma, region, len, capabilities);
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	if (ret < 0)
1341 1342
		goto error_just_free;
	add_nommu_region(region);
1343

1344 1345 1346 1347 1348
	/* clear anonymous mappings that don't ask for uninitialized data */
	if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
		memset((void *)region->vm_start, 0,
		       region->vm_end - region->vm_start);

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	/* okay... we have a mapping; now we have to register it */
1350
	result = vma->vm_start;
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	current->mm->total_vm += len >> PAGE_SHIFT;

1354 1355
share:
	add_vma_to_mm(current->mm, vma);
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1357 1358 1359 1360 1361 1362
	/* we flush the region from the icache only when the first executable
	 * mapping of it is made  */
	if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
		flush_icache_range(region->vm_start, region->vm_end);
		region->vm_icache_flushed = true;
	}
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1364
	up_write(&nommu_region_sem);
L
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1366 1367
	kleave(" = %lx", result);
	return result;
L
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1369 1370 1371
error_just_free:
	up_write(&nommu_region_sem);
error:
1372 1373
	if (region->vm_file)
		fput(region->vm_file);
1374
	kmem_cache_free(vm_region_jar, region);
1375 1376
	if (vma->vm_file)
		fput(vma->vm_file);
1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387
	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;
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1389 1390 1391 1392
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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	       len, current->pid);
	show_free_areas();
	return -ENOMEM;

1397 1398 1399
error_getting_region:
	printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
	       " from process %d failed\n",
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1400 1401 1402 1403
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;
}
1404
EXPORT_SYMBOL(do_mmap_pgoff);
L
Linus Torvalds 已提交
1405

H
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1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430
SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
		unsigned long, prot, unsigned long, flags,
		unsigned long, fd, unsigned long, pgoff)
{
	struct file *file = NULL;
	unsigned long retval = -EBADF;

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

	flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);

	down_write(&current->mm->mmap_sem);
	retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff);
	up_write(&current->mm->mmap_sem);

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

L
Linus Torvalds 已提交
1431
/*
1432 1433
 * 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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1434
 */
1435 1436
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
	      unsigned long addr, int new_below)
L
Linus Torvalds 已提交
1437
{
1438 1439 1440
	struct vm_area_struct *new;
	struct vm_region *region;
	unsigned long npages;
L
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1441

1442
	kenter("");
L
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1443

1444 1445 1446
	/* we're only permitted to split anonymous regions (these should have
	 * only a single usage on the region) */
	if (vma->vm_file)
1447
		return -ENOMEM;
L
Linus Torvalds 已提交
1448

1449 1450
	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;
L
Linus Torvalds 已提交
1451

1452 1453 1454
	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		return -ENOMEM;
L
Linus Torvalds 已提交
1455

1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469
	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) {
1470
		region->vm_top = region->vm_end = new->vm_end = addr;
1471 1472 1473
	} else {
		region->vm_start = new->vm_start = addr;
		region->vm_pgoff = new->vm_pgoff += npages;
L
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1474
	}
1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486

	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;
1487
		vma->vm_region->vm_top = addr;
1488 1489 1490 1491 1492 1493 1494
	}
	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;
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}

1497
/*
1498 1499
 * shrink a VMA by removing the specified chunk from either the beginning or
 * the end
1500
 */
1501 1502 1503
static int shrink_vma(struct mm_struct *mm,
		      struct vm_area_struct *vma,
		      unsigned long from, unsigned long to)
L
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1504
{
1505
	struct vm_region *region;
L
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1506

1507
	kenter("");
L
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1509 1510 1511 1512 1513 1514 1515 1516
	/* 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);
L
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1518 1519
	/* cut the backing region down to size */
	region = vma->vm_region;
1520
	BUG_ON(region->vm_usage != 1);
1521 1522 1523

	down_write(&nommu_region_sem);
	delete_nommu_region(region);
1524 1525 1526 1527
	if (from > region->vm_start) {
		to = region->vm_top;
		region->vm_top = region->vm_end = from;
	} else {
1528
		region->vm_start = to;
1529
	}
1530 1531 1532 1533 1534 1535
	add_nommu_region(region);
	up_write(&nommu_region_sem);

	free_page_series(from, to);
	return 0;
}
L
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1536

1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547
/*
 * 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
Linus Torvalds 已提交
1548

1549
	kenter(",%lx,%zx", start, len);
L
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1550

1551 1552
	if (len == 0)
		return -EINVAL;
1553

1554 1555 1556
	/* find the first potentially overlapping VMA */
	vma = find_vma(mm, start);
	if (!vma) {
1557 1558 1559 1560 1561 1562 1563 1564 1565
		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++;
		}
1566 1567
		return -EINVAL;
	}
L
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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 1603 1604 1605 1606 1607
	/* 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
1608

1609 1610 1611 1612
erase_whole_vma:
	delete_vma_from_mm(vma);
	delete_vma(mm, vma);
	kleave(" = 0");
L
Linus Torvalds 已提交
1613 1614
	return 0;
}
1615
EXPORT_SYMBOL(do_munmap);
L
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1616

1617
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628
{
	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;
}

/*
1629
 * release all the mappings made in a process's VM space
1630
 */
1631
void exit_mmap(struct mm_struct *mm)
L
Linus Torvalds 已提交
1632
{
1633
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1634

1635 1636
	if (!mm)
		return;
L
Linus Torvalds 已提交
1637

1638
	kenter("");
L
Linus Torvalds 已提交
1639

1640
	mm->total_vm = 0;
L
Linus Torvalds 已提交
1641

1642 1643 1644 1645
	while ((vma = mm->mmap)) {
		mm->mmap = vma->vm_next;
		delete_vma_from_mm(vma);
		delete_vma(mm, vma);
L
Linus Torvalds 已提交
1646
	}
1647 1648

	kleave("");
L
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1649 1650 1651 1652 1653 1654 1655 1656
}

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

/*
1657 1658
 * 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
1659
 *
1660
 * under NOMMU conditions, we only permit changing a mapping's size, and only
1661 1662
 * 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
1663
 *
1664
 * MREMAP_FIXED is not supported under NOMMU conditions
L
Linus Torvalds 已提交
1665 1666 1667 1668 1669
 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
1670
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1671 1672

	/* insanity checks first */
1673
	if (old_len == 0 || new_len == 0)
L
Linus Torvalds 已提交
1674 1675
		return (unsigned long) -EINVAL;

1676 1677 1678
	if (addr & ~PAGE_MASK)
		return -EINVAL;

L
Linus Torvalds 已提交
1679 1680 1681
	if (flags & MREMAP_FIXED && new_addr != addr)
		return (unsigned long) -EINVAL;

1682
	vma = find_vma_exact(current->mm, addr, old_len);
1683 1684
	if (!vma)
		return (unsigned long) -EINVAL;
L
Linus Torvalds 已提交
1685

1686
	if (vma->vm_end != vma->vm_start + old_len)
L
Linus Torvalds 已提交
1687 1688
		return (unsigned long) -EFAULT;

1689
	if (vma->vm_flags & VM_MAYSHARE)
L
Linus Torvalds 已提交
1690 1691
		return (unsigned long) -EPERM;

1692
	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
L
Linus Torvalds 已提交
1693 1694 1695
		return (unsigned long) -ENOMEM;

	/* all checks complete - do it */
1696 1697 1698
	vma->vm_end = vma->vm_start + new_len;
	return vma->vm_start;
}
1699
EXPORT_SYMBOL(do_mremap);
1700

1701 1702 1703
SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
		unsigned long, new_len, unsigned long, flags,
		unsigned long, new_addr)
1704 1705 1706 1707 1708 1709 1710
{
	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
1711 1712
}

1713
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1714
			unsigned int foll_flags)
L
Linus Torvalds 已提交
1715 1716 1717 1718 1719 1720 1721
{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
		unsigned long to, unsigned long size, pgprot_t prot)
{
1722 1723
	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
	return 0;
L
Linus Torvalds 已提交
1724
}
1725
EXPORT_SYMBOL(remap_pfn_range);
L
Linus Torvalds 已提交
1726

1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741
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
Linus Torvalds 已提交
1742 1743 1744 1745 1746 1747 1748 1749 1750 1751
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;
}

1752
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1753 1754 1755 1756 1757 1758 1759 1760
{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
1761
EXPORT_SYMBOL(unmap_mapping_range);
L
Linus Torvalds 已提交
1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778

/*
 * 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.
 */
1779
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
L
Linus Torvalds 已提交
1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793
{
	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;

1794
		free = global_page_state(NR_FILE_PAGES);
L
Linus Torvalds 已提交
1795 1796 1797 1798 1799 1800 1801 1802
		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
		 */
1803
		free += global_page_state(NR_SLAB_RECLAIMABLE);
L
Linus Torvalds 已提交
1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818

		/*
		 * 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();
1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830

		/*
		 * 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
1831 1832 1833 1834 1835 1836
		if (!cap_sys_admin)
			n -= n / 32;
		free += n;

		if (free > pages)
			return 0;
1837 1838

		goto error;
L
Linus Torvalds 已提交
1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850
	}

	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
1851 1852
	if (mm)
		allowed -= mm->total_vm / 32;
L
Linus Torvalds 已提交
1853

1854
	if (percpu_counter_read_positive(&vm_committed_as) < allowed)
L
Linus Torvalds 已提交
1855
		return 0;
1856

1857
error:
L
Linus Torvalds 已提交
1858 1859 1860 1861 1862 1863 1864 1865 1866
	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}
1867

N
Nick Piggin 已提交
1868
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1869 1870
{
	BUG();
N
Nick Piggin 已提交
1871
	return 0;
1872
}
1873
EXPORT_SYMBOL(filemap_fault);
1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893

/*
 * 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 */
1894 1895
	vma = find_vma(mm, addr);
	if (vma) {
1896 1897 1898 1899 1900
		/* 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 */
1901
		if (write && vma->vm_flags & VM_MAYWRITE)
1902 1903
			copy_to_user_page(vma, NULL, addr,
					 (void *) addr, buf, len);
1904
		else if (!write && vma->vm_flags & VM_MAYREAD)
1905 1906
			copy_from_user_page(vma, NULL, addr,
					    buf, (void *) addr, len);
1907 1908 1909 1910 1911 1912 1913 1914 1915 1916
		else
			len = 0;
	} else {
		len = 0;
	}

	up_read(&mm->mmap_sem);
	mmput(mm);
	return len;
}
1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978

/**
 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
 * @inode: The inode to check
 * @size: The current filesize of the inode
 * @newsize: The proposed filesize of the inode
 *
 * Check the shared mappings on an inode on behalf of a shrinking truncate to
 * make sure that that any outstanding VMAs aren't broken and then shrink the
 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
 * automatically grant mappings that are too large.
 */
int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
				size_t newsize)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;
	struct vm_region *region;
	pgoff_t low, high;
	size_t r_size, r_top;

	low = newsize >> PAGE_SHIFT;
	high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;

	down_write(&nommu_region_sem);

	/* search for VMAs that fall within the dead zone */
	vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
			      low, high) {
		/* found one - only interested if it's shared out of the page
		 * cache */
		if (vma->vm_flags & VM_SHARED) {
			up_write(&nommu_region_sem);
			return -ETXTBSY; /* not quite true, but near enough */
		}
	}

	/* reduce any regions that overlap the dead zone - if in existence,
	 * these will be pointed to by VMAs that don't overlap the dead zone
	 *
	 * we don't check for any regions that start beyond the EOF as there
	 * shouldn't be any
	 */
	vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap,
			      0, ULONG_MAX) {
		if (!(vma->vm_flags & VM_SHARED))
			continue;

		region = vma->vm_region;
		r_size = region->vm_top - region->vm_start;
		r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;

		if (r_top > newsize) {
			region->vm_top -= r_top - newsize;
			if (region->vm_end > region->vm_top)
				region->vm_end = region->vm_top;
		}
	}

	up_write(&nommu_region_sem);
	return 0;
}