path: root/mm/nommu.c

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

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

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

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

EXPORT_SYMBOL(mem_map);
EXPORT_SYMBOL(sysctl_max_map_count);
EXPORT_SYMBOL(sysctl_overcommit_memory);
EXPORT_SYMBOL(sysctl_overcommit_ratio);
EXPORT_SYMBOL(vm_committed_space);
EXPORT_SYMBOL(__vm_enough_memory);

/* 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);
}

/*
 * The nommu dodgy version :-)
 */
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)
{