nommu.c 45.9 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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#include "internal.h"

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void *high_memory;
struct page *mem_map;
unsigned long max_mapnr;
unsigned long num_physpages;
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atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
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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 = 1; /* page trimming behaviour */
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int heap_stack_gap = 0;

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

		/* protect what we can, including chardevs */
		if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
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		    (!ignore && !(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,
	unsigned long start, int len, int write, int force,
	struct page **pages, struct vm_area_struct **vmas)
{
	int flags = 0;

	if (write)
		flags |= GUP_FLAGS_WRITE;
	if (force)
		flags |= GUP_FLAGS_FORCE;

	return __get_user_pages(tsk, mm,
				start, len, flags,
				pages, vmas);
}
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EXPORT_SYMBOL(get_user_pages);

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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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	vm_region_jar = kmem_cache_create("vm_region_jar",
					  sizeof(struct vm_region), 0,
					  SLAB_PANIC, NULL);
	vm_area_cachep = kmem_cache_create("vm_area_struct",
					   sizeof(struct vm_area_struct), 0,
					   SLAB_PANIC, NULL);
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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);
	if (unlikely(last->vm_end <= last->vm_start))
		BUG();
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	if (unlikely(last->vm_top < last->vm_end))
		BUG();
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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);

		if (unlikely(region->vm_end <= region->vm_start))
			BUG();
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		if (unlikely(region->vm_top < region->vm_end))
			BUG();
		if (unlikely(region->vm_start < last->vm_top))
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			BUG();
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		lastp = p;
	}
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}
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#else
#define validate_nommu_regions() do {} while(0)
#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();

	BUG_ON(region->vm_start & ~PAGE_MASK);

	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);
		atomic_dec(&mmap_pages_allocated);
		if (page_count(page) != 1)
			kdebug("free page %p [%d]", page, page_count(page));
		put_page(page);
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	}
}

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/*
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 * release a reference to a region
 * - the caller must hold the region semaphore, 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);
	}

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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);

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		/* 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;
654
		else if (vma->vm_start > pvma->vm_start)
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			p = &(*p)->rb_right;
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		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);
669 670 671 672 673 674 675 676 677 678 679 680 681 682
	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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}

685
/*
686
 * delete a VMA from its owning mm_struct and address space
687
 */
688
static void delete_vma_from_mm(struct vm_area_struct *vma)
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{
690
	struct vm_area_struct **pp;
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	struct address_space *mapping;
692 693 694 695 696 697 698
	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);
	}

709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817
	/* 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)
{
832
	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;

848
	if (!len)
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		return -EINVAL;

851
	/* Careful about overflows.. */
852 853
	rlen = PAGE_ALIGN(len);
	if (!rlen || rlen > TASK_SIZE)
854 855
		return -ENOMEM;

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	/* offset overflow? */
857
	if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
858
		return -EOVERFLOW;
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	if (file) {
		/* validate file mapping requests */
		struct address_space *mapping;

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

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

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

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

			default:
				return -EINVAL;
			}
		}

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

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

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

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

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

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

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

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

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

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

	/* allow the security API to have its say */
981
	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
	 */
1024
	if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
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		vm_flags &= ~VM_MAYSHARE;

	return vm_flags;
}

/*
1031 1032
 * set up a shared mapping on a file (the driver or filesystem provides and
 * pins the storage)
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 */
1034
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);
1039 1040 1041 1042
	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
 */
1056 1057 1058
static int do_mmap_private(struct vm_area_struct *vma,
			   struct vm_region *region,
			   unsigned long len)
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{
1060 1061
	struct page *pages;
	unsigned long total, point, n, rlen;
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	void *base;
1063
	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);
1071
		if (ret == 0) {
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			/* shouldn't return success if we're not sharing */
1073 1074 1075
			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
			vma->vm_region->vm_top = vma->vm_region->vm_end;
			return ret;
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		}
1077 1078
		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 */
	}

1085 1086
	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
	 */
1091 1092 1093 1094 1095
	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;

1098 1099 1100 1101
	total = 1 << order;
	atomic_add(total, &mmap_pages_allocated);

	point = rlen >> PAGE_SHIFT;
1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114

	/* we allocated a power-of-2 sized page set, so we may want to trim off
	 * the excess */
	if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
		while (total > point) {
			order = ilog2(total - point);
			n = 1 << order;
			kdebug("shave %lu/%lu @%lu", n, total - point, total);
			atomic_sub(n, &mmap_pages_allocated);
			total -= n;
			set_page_refcounted(pages + total);
			__free_pages(pages + total, order);
		}
1115 1116 1117 1118
	}

	for (point = 1; point < total; point++)
		set_page_refcounted(&pages[point]);
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1120 1121 1122 1123
	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;
1124
	region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1125 1126 1127

	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);
1139
		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 */
1146 1147
		if (ret < rlen)
			memset(base + ret, 0, rlen - ret);
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	} else {
		/* if it's an anonymous mapping, then just clear it */
1151
		memset(base, 0, rlen);
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	}

	return 0;

error_free:
1157 1158 1159
	free_page_series(region->vm_start, region->vm_end);
	region->vm_start = vma->vm_start = 0;
	region->vm_end   = vma->vm_end = 0;
1160
	region->vm_top   = 0;
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	return ret;

enomem:
1164 1165
	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)
{
1180 1181
	struct vm_area_struct *vma;
	struct vm_region *region;
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	struct rb_node *rb;
1183
	unsigned long capabilities, vm_flags, result;
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	int ret;

1186 1187
	kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);

1188 1189 1190
	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);
1195 1196
	if (ret < 0) {
		kleave(" = %d [val]", ret);
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		return ret;
1198
	}
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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);

1204 1205 1206 1207 1208 1209 1210 1211
	/* 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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1213 1214 1215 1216 1217 1218 1219
	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;
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1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234
	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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1235
	 * mmap() calls that overlap with our proposed mapping
1236
	 * - we can only share with a superset match on most regular files
L
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1237 1238 1239 1240 1241 1242
	 * - 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) {
1243 1244
		struct vm_region *pregion;
		unsigned long pglen, rpglen, pgend, rpgend, start;
L
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1245

1246 1247
		pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		pgend = pgoff + pglen;
1248

1249 1250
		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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1251

1252
			if (!(pregion->vm_flags & VM_MAYSHARE))
L
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1253 1254 1255
				continue;

			/* search for overlapping mappings on the same file */
1256 1257
			if (pregion->vm_file->f_path.dentry->d_inode !=
			    file->f_path.dentry->d_inode)
L
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1258 1259
				continue;

1260
			if (pregion->vm_pgoff >= pgend)
L
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1261 1262
				continue;

1263 1264 1265 1266
			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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1267 1268
				continue;

1269 1270 1271 1272 1273
			/* 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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1274 1275 1276 1277 1278
				if (!(capabilities & BDI_CAP_MAP_DIRECT))
					goto sharing_violation;
				continue;
			}

1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306
			/* 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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1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318
		}

		/* 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)
1319
					goto error_just_free;
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1320 1321 1322 1323 1324 1325

				/* 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))
1326
					goto error_just_free;
L
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1327 1328

				capabilities &= ~BDI_CAP_MAP_DIRECT;
1329 1330 1331
			} else {
				vma->vm_start = region->vm_start = addr;
				vma->vm_end = region->vm_end = addr + len;
L
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1332 1333 1334 1335
			}
		}
	}

1336
	vma->vm_region = region;
L
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	/* set up the mapping */
	if (file && vma->vm_flags & VM_SHARED)
1340
		ret = do_mmap_shared_file(vma);
L
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1341
	else
1342
		ret = do_mmap_private(vma, region, len);
L
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1343
	if (ret < 0)
1344 1345 1346
		goto error_put_region;

	add_nommu_region(region);
L
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1347 1348

	/* okay... we have a mapping; now we have to register it */
1349
	result = vma->vm_start;
L
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1350 1351 1352

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

1353 1354
share:
	add_vma_to_mm(current->mm, vma);
L
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1355

1356
	up_write(&nommu_region_sem);
L
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1357 1358

	if (prot & PROT_EXEC)
1359
		flush_icache_range(result, result + len);
L
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1360

1361 1362
	kleave(" = %lx", result);
	return result;
L
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1363

1364 1365
error_put_region:
	__put_nommu_region(region);
L
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	if (vma) {
M
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		if (vma->vm_file) {
1368
			fput(vma->vm_file);
M
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1369 1370 1371
			if (vma->vm_flags & VM_EXECUTABLE)
				removed_exe_file_vma(vma->vm_mm);
		}
1372
		kmem_cache_free(vm_area_cachep, vma);
L
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1373
	}
1374
	kleave(" = %d [pr]", ret);
L
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1375 1376
	return ret;

1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393
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;
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1395 1396 1397 1398
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",
L
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	       len, current->pid);
	show_free_areas();
	return -ENOMEM;

1403 1404 1405
error_getting_region:
	printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
	       " from process %d failed\n",
L
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1406 1407 1408 1409
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;
}
1410
EXPORT_SYMBOL(do_mmap_pgoff);
L
Linus Torvalds 已提交
1411 1412

/*
1413 1414
 * split a vma into two pieces at address 'addr', a new vma is allocated either
 * for the first part or the tail.
L
Linus Torvalds 已提交
1415
 */
1416 1417
int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
	      unsigned long addr, int new_below)
L
Linus Torvalds 已提交
1418
{
1419 1420 1421
	struct vm_area_struct *new;
	struct vm_region *region;
	unsigned long npages;
L
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1422

1423
	kenter("");
L
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1424

1425 1426 1427 1428 1429
	/* 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
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1430

1431 1432
	if (mm->map_count >= sysctl_max_map_count)
		return -ENOMEM;
L
Linus Torvalds 已提交
1433

1434 1435 1436
	region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
	if (!region)
		return -ENOMEM;
L
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1437

1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451
	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) {
1452
		region->vm_top = region->vm_end = new->vm_end = addr;
1453 1454 1455
	} else {
		region->vm_start = new->vm_start = addr;
		region->vm_pgoff = new->vm_pgoff += npages;
L
Linus Torvalds 已提交
1456
	}
1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468

	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;
1469
		vma->vm_region->vm_top = addr;
1470 1471 1472 1473 1474 1475 1476
	}
	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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1477 1478
}

1479
/*
1480 1481
 * shrink a VMA by removing the specified chunk from either the beginning or
 * the end
1482
 */
1483 1484 1485
static int shrink_vma(struct mm_struct *mm,
		      struct vm_area_struct *vma,
		      unsigned long from, unsigned long to)
L
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1486
{
1487
	struct vm_region *region;
L
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1488

1489
	kenter("");
L
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1490

1491 1492 1493 1494 1495 1496 1497 1498
	/* 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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1500 1501 1502 1503 1504 1505
	/* 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);
1506 1507 1508 1509
	if (from > region->vm_start) {
		to = region->vm_top;
		region->vm_top = region->vm_end = from;
	} else {
1510
		region->vm_start = to;
1511
	}
1512 1513 1514 1515 1516 1517
	add_nommu_region(region);
	up_write(&nommu_region_sem);

	free_page_series(from, to);
	return 0;
}
L
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1518

1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529
/*
 * 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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1530

1531
	kenter(",%lx,%zx", start, len);
L
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1532

1533 1534
	if (len == 0)
		return -EINVAL;
1535

1536 1537 1538 1539 1540 1541 1542 1543 1544
	/* find the first potentially overlapping VMA */
	vma = find_vma(mm, start);
	if (!vma) {
		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);
		return -EINVAL;
	}
L
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1545

1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584
	/* 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
1585

1586 1587 1588 1589
erase_whole_vma:
	delete_vma_from_mm(vma);
	delete_vma(mm, vma);
	kleave(" = 0");
L
Linus Torvalds 已提交
1590 1591
	return 0;
}
1592
EXPORT_SYMBOL(do_munmap);
L
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1593

1594
SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605
{
	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;
}

/*
1606
 * release all the mappings made in a process's VM space
1607
 */
1608
void exit_mmap(struct mm_struct *mm)
L
Linus Torvalds 已提交
1609
{
1610
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1611

1612 1613
	if (!mm)
		return;
L
Linus Torvalds 已提交
1614

1615
	kenter("");
L
Linus Torvalds 已提交
1616

1617
	mm->total_vm = 0;
L
Linus Torvalds 已提交
1618

1619 1620 1621 1622
	while ((vma = mm->mmap)) {
		mm->mmap = vma->vm_next;
		delete_vma_from_mm(vma);
		delete_vma(mm, vma);
L
Linus Torvalds 已提交
1623
	}
1624 1625

	kleave("");
L
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1626 1627 1628 1629 1630 1631 1632 1633
}

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

/*
1634 1635
 * 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
1636
 *
1637
 * under NOMMU conditions, we only permit changing a mapping's size, and only
1638 1639
 * 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
1640
 *
1641
 * MREMAP_FIXED is not supported under NOMMU conditions
L
Linus Torvalds 已提交
1642 1643 1644 1645 1646
 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
1647
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1648 1649

	/* insanity checks first */
1650
	if (old_len == 0 || new_len == 0)
L
Linus Torvalds 已提交
1651 1652
		return (unsigned long) -EINVAL;

1653 1654 1655
	if (addr & ~PAGE_MASK)
		return -EINVAL;

L
Linus Torvalds 已提交
1656 1657 1658
	if (flags & MREMAP_FIXED && new_addr != addr)
		return (unsigned long) -EINVAL;

1659
	vma = find_vma_exact(current->mm, addr, old_len);
1660 1661
	if (!vma)
		return (unsigned long) -EINVAL;
L
Linus Torvalds 已提交
1662

1663
	if (vma->vm_end != vma->vm_start + old_len)
L
Linus Torvalds 已提交
1664 1665
		return (unsigned long) -EFAULT;

1666
	if (vma->vm_flags & VM_MAYSHARE)
L
Linus Torvalds 已提交
1667 1668
		return (unsigned long) -EPERM;

1669
	if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
L
Linus Torvalds 已提交
1670 1671 1672
		return (unsigned long) -ENOMEM;

	/* all checks complete - do it */
1673 1674 1675
	vma->vm_end = vma->vm_start + new_len;
	return vma->vm_start;
}
1676
EXPORT_SYMBOL(do_mremap);
1677

1678 1679 1680
SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
		unsigned long, new_len, unsigned long, flags,
		unsigned long, new_addr)
1681 1682 1683 1684 1685 1686 1687
{
	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
1688 1689
}

1690
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1691
			unsigned int foll_flags)
L
Linus Torvalds 已提交
1692 1693 1694 1695 1696 1697 1698
{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
		unsigned long to, unsigned long size, pgprot_t prot)
{
1699 1700
	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
	return 0;
L
Linus Torvalds 已提交
1701
}
1702
EXPORT_SYMBOL(remap_pfn_range);
L
Linus Torvalds 已提交
1703

1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718
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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1719 1720 1721 1722 1723 1724 1725 1726 1727 1728
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;
}

1729
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
L
Linus Torvalds 已提交
1730 1731 1732 1733 1734 1735 1736 1737
{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
1738
EXPORT_SYMBOL(unmap_mapping_range);
L
Linus Torvalds 已提交
1739

1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760
/*
 * 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
1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776
/*
 * 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.
 */
1777
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
L
Linus Torvalds 已提交
1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791
{
	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;

1792
		free = global_page_state(NR_FILE_PAGES);
L
Linus Torvalds 已提交
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		free += nr_swap_pages;

		/*
		 * Any slabs which are created with the
		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
		 * which are reclaimable, under pressure.  The dentry
		 * cache and most inode caches should fall into this
		 */
1801
		free += global_page_state(NR_SLAB_RECLAIMABLE);
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		/*
		 * Leave the last 3% for root
		 */
		if (!cap_sys_admin)
			free -= free / 32;

		if (free > pages)
			return 0;

		/*
		 * nr_free_pages() is very expensive on large systems,
		 * only call if we're about to fail.
		 */
		n = nr_free_pages();
1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828

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

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

		if (free > pages)
			return 0;
1835 1836

		goto error;
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Linus Torvalds 已提交
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	}

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

	/* Don't let a single process grow too big:
	   leave 3% of the size of this process for other processes */
A
Alan Cox 已提交
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	if (mm)
		allowed -= mm->total_vm / 32;
L
Linus Torvalds 已提交
1851

1852 1853 1854 1855
	/*
	 * cast `allowed' as a signed long because vm_committed_space
	 * sometimes has a negative value
	 */
A
Alan Cox 已提交
1856
	if (atomic_long_read(&vm_committed_space) < (long)allowed)
L
Linus Torvalds 已提交
1857
		return 0;
1858
error:
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Linus Torvalds 已提交
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	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}
1868

N
Nick Piggin 已提交
1869
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1870 1871
{
	BUG();
N
Nick Piggin 已提交
1872
	return 0;
1873
}
1874
EXPORT_SYMBOL(filemap_fault);
1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894

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

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