nommu.c 33.1 KB
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/*
 *  linux/mm/nommu.c
 *
 *  Replacement code for mm functions to support CPU's that don't
 *  have any form of memory management unit (thus no virtual memory).
 *
 *  See Documentation/nommu-mmap.txt
 *
 *  Copyright (c) 2004-2005 David Howells <dhowells@redhat.com>
 *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
 *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
 *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
 */

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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>
#include <linux/ptrace.h>
#include <linux/blkdev.h>
#include <linux/backing-dev.h>
#include <linux/mount.h>
#include <linux/personality.h>
#include <linux/security.h>
#include <linux/syscalls.h>

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

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

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

struct vm_operations_struct generic_file_vm_ops = {
};

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

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

	truncate_inode_pages(mapping, offset);
	goto out_truncate;

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

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

EXPORT_SYMBOL(vmtruncate);

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

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

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

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

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

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

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

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

finish_or_fault:
	return i ? : -EFAULT;
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}
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EXPORT_SYMBOL(get_user_pages);

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DEFINE_RWLOCK(vmlist_lock);
struct vm_struct *vmlist;

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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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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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/**
 * 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.
 */
void *vmalloc_32_user(unsigned long size)
{
	return __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
}
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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/*
 * 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.
 */
asmlinkage unsigned long sys_brk(unsigned long brk)
{
	struct mm_struct *mm = current->mm;

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

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

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

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

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

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

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

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

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

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

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

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

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

	return NULL;
}
EXPORT_SYMBOL(find_vma);

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

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

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

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

	return NULL;
}

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

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

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

	return NULL;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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	if (!len)
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		return -EINVAL;

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

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

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

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

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

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

			default:
				return -EINVAL;
			}
		}

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

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

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

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

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

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

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

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

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

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

	/* allow the security API to have its say */
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	ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
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667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761
	if (ret < 0)
		return ret;

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

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

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

	if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
		/* attempt to share read-only copies of mapped file chunks */
		if (file && !(prot & PROT_WRITE))
			vm_flags |= VM_MAYSHARE;
	}
	else {
		/* overlay a shareable mapping on the backing device or inode
		 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
		 * romfs/cramfs */
		if (flags & MAP_SHARED)
			vm_flags |= VM_MAYSHARE | VM_SHARED;
		else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
			vm_flags |= VM_MAYSHARE;
	}

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

	return vm_flags;
}

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

	ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
	if (ret != -ENOSYS)
		return ret;

	/* getting an ENOSYS error indicates that direct mmap isn't
	 * possible (as opposed to tried but failed) so we'll fall
	 * through to making a private copy of the data and mapping
	 * that if we can */
	return -ENODEV;
}

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

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

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

	/* allocate some memory to hold the mapping
	 * - note that this may not return a page-aligned address if the object
	 *   we're allocating is smaller than a page
	 */
762
	base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
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	if (!base)
		goto enomem;

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

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

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

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

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

		if (ret < 0)
			goto error_free;

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

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

	return 0;

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

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

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

832 833 834
	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);
	if (ret < 0)
		return ret;

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

	/* we're going to need to record the mapping if it works */
847
	vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
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	if (!vml)
		goto error_getting_vml;

	down_write(&nommu_vma_sem);

	/* if we want to share, we need to check for VMAs created by other
	 * mmap() calls that overlap with our proposed mapping
	 * - we can only share with an exact match on most regular files
	 * - shared mappings on character devices and memory backed files are
	 *   permitted to overlap inexactly as far as we are concerned for in
	 *   these cases, sharing is handled in the driver or filesystem rather
	 *   than here
	 */
	if (vm_flags & VM_MAYSHARE) {
		unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
		unsigned long vmpglen;

865 866 867 868 869
		/* suppress VMA sharing for shared regions */
		if (vm_flags & VM_SHARED &&
		    capabilities & BDI_CAP_MAP_DIRECT)
			goto dont_share_VMAs;

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

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

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

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

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

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

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

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

903
	dont_share_VMAs:
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		vma = NULL;

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

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

				capabilities &= ~BDI_CAP_MAP_DIRECT;
			}
		}
	}

	/* we're going to need a VMA struct as well */
931
	vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
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	if (!vma)
		goto error_getting_vma;

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

	vml->vma = vma;

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

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

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

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

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

	add_nommu_vma(vma);

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

974
	add_vma_to_mm(current->mm, vml);
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	up_write(&nommu_vma_sem);

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

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

	return (unsigned long) result;

 error:
	up_write(&nommu_vma_sem);
	kfree(vml);
	if (vma) {
993 994
		if (vma->vm_file)
			fput(vma->vm_file);
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		kfree(vma);
	}
	return ret;

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

 error_getting_vma:
	up_write(&nommu_vma_sem);
	kfree(vml);
1008
	printk("Allocation of vma for %lu byte allocation from process %d failed\n",
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	       len, current->pid);
	show_free_areas();
	return -ENOMEM;

 error_getting_vml:
	printk("Allocation of vml for %lu byte allocation from process %d failed\n",
	       len, current->pid);
	show_free_areas();
	return -ENOMEM;
}
1019
EXPORT_SYMBOL(do_mmap_pgoff);
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/*
 * handle mapping disposal for uClinux
 */
static void put_vma(struct vm_area_struct *vma)
{
	if (vma) {
		down_write(&nommu_vma_sem);

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

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

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

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

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

		up_write(&nommu_vma_sem);
	}
}

1055 1056 1057 1058 1059
/*
 * release a mapping
 * - under NOMMU conditions the parameters must match exactly to the mapping to
 *   be removed
 */
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int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
{
	struct vm_list_struct *vml, **parent;
	unsigned long end = addr + len;

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

1069 1070 1071
	for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
		if ((*parent)->vma->vm_start > addr)
			break;
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		if ((*parent)->vma->vm_start == addr &&
1073
		    ((len == 0) || ((*parent)->vma->vm_end == end)))
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			goto found;
1075
	}
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	printk("munmap of non-mmaped memory by process %d (%s): %p\n",
	       current->pid, current->comm, (void *) addr);
	return -EINVAL;

 found:
	vml = *parent;

	put_vma(vml->vma);

	*parent = vml->next;
	realalloc -= kobjsize(vml);
	askedalloc -= sizeof(*vml);
	kfree(vml);
1090 1091

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

#ifdef DEBUG
	show_process_blocks();
#endif

	return 0;
}
1100
EXPORT_SYMBOL(do_munmap);
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1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115
asmlinkage long sys_munmap(unsigned long addr, size_t len)
{
	int ret;
	struct mm_struct *mm = current->mm;

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

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

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

		mm->total_vm = 0;

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

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

#ifdef DEBUG
		show_process_blocks();
#endif
	}
}

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

/*
1148 1149
 * expand (or shrink) an existing mapping, potentially moving it at the same
 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
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 *
1151 1152 1153
 * under NOMMU conditions, we only permit changing a mapping's size, and only
 * as long as it stays within the hole allocated by the kmalloc() call in
 * do_mmap_pgoff() and the block is not shareable
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 *
1155
 * MREMAP_FIXED is not supported under NOMMU conditions
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 */
unsigned long do_mremap(unsigned long addr,
			unsigned long old_len, unsigned long new_len,
			unsigned long flags, unsigned long new_addr)
{
1161
	struct vm_area_struct *vma;
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	/* insanity checks first */
	if (new_len == 0)
		return (unsigned long) -EINVAL;

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

1170 1171 1172
	vma = find_vma_exact(current->mm, addr);
	if (!vma)
		return (unsigned long) -EINVAL;
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1174
	if (vma->vm_end != vma->vm_start + old_len)
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		return (unsigned long) -EFAULT;

1177
	if (vma->vm_flags & VM_MAYSHARE)
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		return (unsigned long) -EPERM;

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

	/* all checks complete - do it */
1184
	vma->vm_end = vma->vm_start + new_len;
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	askedalloc -= old_len;
	askedalloc += new_len;

1189 1190
	return vma->vm_start;
}
1191
EXPORT_SYMBOL(do_mremap);
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202

asmlinkage unsigned long sys_mremap(unsigned long addr,
	unsigned long old_len, unsigned long new_len,
	unsigned long flags, unsigned long new_addr)
{
	unsigned long ret;

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

1205
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1206
			unsigned int foll_flags)
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{
	return NULL;
}

int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
		unsigned long to, unsigned long size, pgprot_t prot)
{
1214 1215
	vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
	return 0;
L
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}
1217
EXPORT_SYMBOL(remap_pfn_range);
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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;
}

1229
void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
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{
}

void unmap_mapping_range(struct address_space *mapping,
			 loff_t const holebegin, loff_t const holelen,
			 int even_cows)
{
}
1238
EXPORT_SYMBOL(unmap_mapping_range);
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1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260
/*
 * 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);

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/*
 * 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.
 */
1277
int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
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{
	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;

1292
		free = global_page_state(NR_FILE_PAGES);
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		free += nr_swap_pages;

		/*
		 * Any slabs which are created with the
		 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
		 * which are reclaimable, under pressure.  The dentry
		 * cache and most inode caches should fall into this
		 */
1301
		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();
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		/*
		 * Leave reserved pages. The pages are not for anonymous pages.
		 */
		if (n <= totalreserve_pages)
			goto error;
		else
			n -= totalreserve_pages;

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

		if (free > pages)
			return 0;
1335 1336

		goto error;
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	}

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

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

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	/*
	 * cast `allowed' as a signed long because vm_committed_space
	 * sometimes has a negative value
	 */
	if (atomic_read(&vm_committed_space) < (long)allowed)
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		return 0;
1357
error:
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	vm_unacct_memory(pages);

	return -ENOMEM;
}

int in_gate_area_no_task(unsigned long addr)
{
	return 0;
}
1367

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int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
	BUG();
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	return 0;
1372
}
1373
EXPORT_SYMBOL(filemap_fault);
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/*
 * Access another process' address space.
 * - source/target buffer must be kernel space
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
{
	struct vm_area_struct *vma;
	struct mm_struct *mm;

	if (addr + len < addr)
		return 0;

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

	down_read(&mm->mmap_sem);

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

		/* only read or write mappings where it is permitted */
1401
		if (write && vma->vm_flags & VM_MAYWRITE)
1402
			len -= copy_to_user((void *) addr, buf, len);
1403
		else if (!write && vma->vm_flags & VM_MAYREAD)
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			len -= copy_from_user(buf, (void *) addr, len);
		else
			len = 0;
	} else {
		len = 0;
	}

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