path: root/kernel/power/swsusp.c

/*
 * linux/kernel/power/swsusp.c
 *
 * This file provides code to write suspend image to swap and read it back.
 *
 * Copyright (C) 1998-2001 Gabor Kuti <seasons@fornax.hu>
 * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@suse.cz>
 *
 * This file is released under the GPLv2.
 *
 * I'd like to thank the following people for their work:
 *
 * Pavel Machek <pavel@ucw.cz>:
 * Modifications, defectiveness pointing, being with me at the very beginning,
 * suspend to swap space, stop all tasks. Port to 2.4.18-ac and 2.5.17.
 *
 * Steve Doddi <dirk@loth.demon.co.uk>:
 * Support the possibility of hardware state restoring.
 *
 * Raph <grey.havens@earthling.net>:
 * Support for preserving states of network devices and virtual console
 * (including X and svgatextmode)
 *
 * Kurt Garloff <garloff@suse.de>:
 * Straightened the critical function in order to prevent compilers from
 * playing tricks with local variables.
 *
 * Andreas Mohr <a.mohr@mailto.de>
 *
 * Alex Badea <vampire@go.ro>:
 * Fixed runaway init
 *
 * Rafael J. Wysocki <rjw@sisk.pl>
 * Added the swap map data structure and reworked the handling of swap
 *
 * More state savers are welcome. Especially for the scsi layer...
 *
 * For TODOs,FIXMEs also look in Documentation/power/swsusp.txt
 */

#include <linux/module.h>
#include <linux/mm.h>
#include <linux/suspend.h>
#include <linux/smp_lock.h>
#include <linux/file.h>
#include <linux/utsname.h>
#include <linux/version.h>
#include <linux/delay.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/genhd.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/swap.h>
#include <linux/pm.h>
#include <linux/device.h>
#include <linux/buffer_head.h>
#include <linux/swapops.h>
#include <linux/bootmem.h>
#include <linux/syscalls.h>
#include <linux/highmem.h>
#include <linux/bio.h>

#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/io.h>

#include "power.h"

/*
 * Preferred image size in bytes (tunable via /sys/power/image_size).
 * When it is set to N, swsusp will do its best to ensure the image
 * size will not exceed N bytes, but if that is impossible, it will
 * try to create the smallest image possible.
 */
unsigned long image_size = 500 * 1024 * 1024;

#ifdef CONFIG_HIGHMEM
unsigned int count_highmem_pages(void);
int save_highmem(void);
int restore_highmem(void);
#else
static int save_highmem(void) { return 0; }
static int restore_highmem(void) { return 0; }
static unsigned int count_highmem_pages(void) { return 0; }
#endif

extern char resume_file[];

#define SWSUSP_SIG	"S1SUSPEND"

static struct swsusp_header {
	char reserved[PAGE_SIZE - 20 - sizeof(swp_entry_t)];
	swp_entry_t image;
	char	orig_sig[10];
	char	sig[10];
} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;

static struct swsusp_info swsusp_info;

/*
 * Saving part...
 */

static unsigned short root_swap = 0xffff;

static int mark_swapfiles(swp_entry_t start)
{
	int error;

	rw_swap_page_sync(READ,
			  swp_entry(root_swap, 0),
			  virt_to_page((unsigned long)&swsusp_header));
	if (!memcmp("SWAP-SPACE",swsusp_header.sig, 10) ||
	    !memcmp("SWAPSPACE2",swsusp_header.sig, 10)) {
		memcpy(swsusp_header.orig_sig,swsusp_header.sig, 10);
		memcpy(swsusp_header.sig,SWSUSP_SIG, 10);
		swsusp_header.image = start;
		error = rw_swap_page_sync(WRITE,
					  swp_entry(root_swap, 0),
					  virt_to_page((unsigned long)
						       &swsusp_header));
	} else {
		pr_debug("swsusp: Partition is not swap space.\n");
		error = -ENODEV;
	}
	return error;
}

/*
 * Check whether the swap device is the specified resume
 * device, irrespective of whether they are specified by
 * identical names.
 *
 * (Thus, device inode aliasing is allowed.  You can say /dev/hda4
 * instead of /dev/ide/host0/bus0/target0/lun0/part4 [if using devfs]
 * and they'll be considered the same device.  This is *necessary* for
 * devfs, since the resume code can only recognize the form /dev/hda4,
 * but the suspend code would see the long name.)
 */
static inline int is_resume_device(const struct swap_info_struct *swap_info)
{
	struct file *file = swap_info->swap_file;
	struct inode *inode = file->f_dentry->d_inode;

	return S_ISBLK(inode->i_mode) &&
		swsusp_resume_device == MKDEV(imajor(inode), iminor(inode));
}

static int swsusp_swap_check(void) /* This is called before saving image */
{
	int i;

	if (!swsusp_resume_device)
		return -ENODEV;
	spin_lock(&swap_lock);
	for (i = 0; i < MAX_SWAPFILES; i++) {
		if (!(swap_info[i].flags & SWP_WRITEOK))
			continue;
		if (is_resume_device(swap_info + i)) {
			spin_unlock(&swap_lock);
			root_swap = i;
			return 0;
		}
	}
	spin_unlock(&swap_lock);
	return -ENODEV;
}

/**
 *	write_page - Write one page to a fresh swap location.
 *	@addr:	Address we're writing.
 *	@loc:	Place to store the entry we used.
 *
 *	Allocate a new swap entry and 'sync' it. Note we discard -EIO
 *	errors. That is an artifact left over from swsusp. It did not
 *	check the return of rw_swap_page_sync() at all, since most pages
 *	written back to swap would return -EIO.