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// SPDX-License-Identifier: GPL-2.0-only/* * linux/kernel/power/swap.c * * This file provides functions for reading the suspend image from * and writing it to a swap partition. * * Copyright (C) 1998,2001-2005 Pavel Machek <pavel@ucw.cz> * Copyright (C) 2006 Rafael J. Wysocki <rjw@sisk.pl> * Copyright (C) 2010-2012 Bojan Smojver <bojan@rexursive.com> */ #define pr_fmt(fmt) "PM: " fmt #include <crypto/acompress.h>#include <linux/module.h>#include <linux/file.h>#include <linux/delay.h>#include <linux/bitops.h>#include <linux/device.h>#include <linux/bio.h>#include <linux/blkdev.h>#include <linux/swap.h>#include <linux/swapops.h>#include <linux/pm.h>#include <linux/slab.h>#include <linux/vmalloc.h>#include <linux/cpumask.h>#include <linux/atomic.h>#include <linux/kthread.h>#include <linux/crc32.h>#include <linux/ktime.h> #include "power.h" #define HIBERNATE_SIG	"S1SUSPEND" u32 swsusp_hardware_signature; /* * When reading an {un,}compressed image, we may restore pages in place, * in which case some architectures need these pages cleaning before they * can be executed. We don't know which pages these may be, so clean the lot. */static bool clean_pages_on_read;static bool clean_pages_on_decompress; /* * The swap map is a data structure used for keeping track of each page * written to a swap partition.  It consists of many swap_map_page structures * that contain each an array of MAP_PAGE_ENTRIES swap entries.  These * structures are stored on the swap and linked together with the help of the * .next_swap member. * * The swap map is created during suspend.  The swap map pages are allocated and * populated one at a time, so we only need one memory page to set up the entire * structure. * * During resume we pick up all swap_map_page structures into a list. */#define MAP_PAGE_ENTRIES	(PAGE_SIZE / sizeof(sector_t) - 1) /* * Number of free pages that are not high. */static inline unsigned long low_free_pages(void){	return nr_free_pages() - nr_free_highpages();} /* * Number of pages required to be kept free while writing the image. Always * half of all available low pages before the writing starts. */static inline unsigned long reqd_free_pages(void){	return low_free_pages() / 2;} struct swap_map_page {	sector_t entries[MAP_PAGE_ENTRIES];	sector_t next_swap;}; struct swap_map_page_list {	struct swap_map_page *map;	struct swap_map_page_list *next;}; /* * The swap_map_handle structure is used for handling swap in a file-alike way. */struct swap_map_handle {	struct swap_map_page *cur;	struct swap_map_page_list *maps;	sector_t cur_swap;	sector_t first_sector;	unsigned int k;	unsigned long reqd_free_pages;	u32 crc32;}; struct swsusp_header {	char reserved[PAGE_SIZE - 20 - sizeof(sector_t) - sizeof(int) -	              sizeof(u32) - sizeof(u32)];	u32	hw_sig;	u32	crc32;	sector_t image;	unsigned int flags;	/* Flags to pass to the "boot" kernel */	char	orig_sig[10];	char	sig[10];} __packed; static struct swsusp_header *swsusp_header; /* * The following functions are used for tracing the allocated swap pages, so * that they can be freed in case of an error. */struct swsusp_extent {	struct rb_node node;	unsigned long start;	unsigned long end;}; static struct rb_root swsusp_extents = RB_ROOT; static int swsusp_extents_insert(unsigned long swap_offset){	struct rb_node **new = &(swsusp_extents.rb_node);	struct rb_node *parent = NULL;	struct swsusp_extent *ext; 	/* Figure out where to put the new node */	while (*new) {		ext = rb_entry(*new, struct swsusp_extent, node);		parent = *new;		if (swap_offset < ext->start) {			/* Try to merge */			if (swap_offset == ext->start - 1) {				ext->start--;				return 0;			}			new = &((*new)->rb_left);		} else if (swap_offset > ext->end) {			/* Try to merge */			if (swap_offset == ext->end + 1) {				ext->end++;				return 0;			}			new = &((*new)->rb_right);		} else {			/* It already is in the tree */			return -EINVAL;		}	}	/* Add the new node and rebalance the tree. */	ext = kzalloc_obj(struct swsusp_extent);	if (!ext)		return -ENOMEM; 	ext->start = swap_offset;	ext->end = swap_offset;	rb_link_node(&ext->node, parent, new);	rb_insert_color(&ext->node, &swsusp_extents);	return 0;} sector_t alloc_swapdev_block(int swap){	unsigned long offset; 	/*	 * Allocate a swap page and register that it has been allocated, so that	 * it can be freed in case of an error.	 */	offset = swp_offset(swap_alloc_hibernation_slot(swap));	if (offset) {		if (swsusp_extents_insert(offset))			swap_free_hibernation_slot(swp_entry(swap, offset));		else			return swapdev_block(swap, offset);	}	return 0;} void free_all_swap_pages(int swap){	unsigned long offset;	struct rb_node *node; 	/*	 * Free swap pages allocated for saving image data.  It also frees the	 * extents used to register which swap entries had been allocated.	 */	while ((node = swsusp_extents.rb_node)) {		struct swsusp_extent *ext; 		ext = rb_entry(node, struct swsusp_extent, node);		rb_erase(node, &swsusp_extents); 		for (offset = ext->start; offset <= ext->end; offset++)			swap_free_hibernation_slot(swp_entry(swap, offset)); 		kfree(ext);	}} int swsusp_swap_in_use(void){	return (swsusp_extents.rb_node != NULL);} /* * General things */ static unsigned short root_swap = 0xffff;static struct file *hib_resume_bdev_file; struct hib_bio_batch {	atomic_t		count;	wait_queue_head_t	wait;	blk_status_t		error;	struct blk_plug		plug;}; static void hib_init_batch(struct hib_bio_batch *hb){	atomic_set(&hb->count, 0);	init_waitqueue_head(&hb->wait);	hb->error = BLK_STS_OK;	blk_start_plug(&hb->plug);} static void hib_finish_batch(struct hib_bio_batch *hb){	blk_finish_plug(&hb->plug);} static void hib_end_io(struct bio *bio){	struct hib_bio_batch *hb = bio->bi_private;	struct page *page = bio_first_page_all(bio); 	if (bio->bi_status) {		pr_alert("Read-error on swap-device (%u:%u:%Lu)\n",			 MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)),			 (unsigned long long)bio->bi_iter.bi_sector);	} 	if (bio_data_dir(bio) == WRITE)		put_page(page);	else if (clean_pages_on_read)		flush_icache_range((unsigned long)page_address(page),				   (unsigned long)page_address(page) + PAGE_SIZE); 	if (bio->bi_status && !hb->error)		hb->error = bio->bi_status;	if (atomic_dec_and_test(&hb->count))		wake_up(&hb->wait); 	bio_put(bio);} static int hib_submit_io_sync(blk_opf_t opf, pgoff_t page_off, void *addr){	return bdev_rw_virt(file_bdev(hib_resume_bdev_file),			page_off * (PAGE_SIZE >> 9), addr, PAGE_SIZE, opf);} static int hib_submit_io_async(blk_opf_t opf, pgoff_t page_off, void *addr,			 struct hib_bio_batch *hb){	struct bio *bio; 	bio = bio_alloc(file_bdev(hib_resume_bdev_file), 1, opf,			GFP_NOIO | __GFP_HIGH);	bio->bi_iter.bi_sector = page_off * (PAGE_SIZE >> 9);	bio_add_virt_nofail(bio, addr, PAGE_SIZE);	bio->bi_end_io = hib_end_io;	bio->bi_private = hb;	atomic_inc(&hb->count);	submit_bio(bio);	return 0;} static int hib_wait_io(struct hib_bio_batch *hb){	/*	 * We are relying on the behavior of blk_plug that a thread with	 * a plug will flush the plug list before sleeping.	 */	wait_event(hb->wait, atomic_read(&hb->count) == 0);	return blk_status_to_errno(hb->error);} /* * Saving part */ static int mark_swapfiles(struct swap_map_handle *handle, unsigned int flags){	int error; 	hib_submit_io_sync(REQ_OP_READ, swsusp_resume_block, 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, HIBERNATE_SIG, 10);		swsusp_header->image = handle->first_sector;		if (swsusp_hardware_signature) {			swsusp_header->hw_sig = swsusp_hardware_signature;			flags |= SF_HW_SIG;		}		swsusp_header->flags = flags;		if (flags & SF_CRC32_MODE)			swsusp_header->crc32 = handle->crc32;		error = hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC,				      swsusp_resume_block, swsusp_header);	} else {		pr_err("Swap header not found!\n");		error = -ENODEV;	}	return error;} /* * Hold the swsusp_header flag. This is used in software_resume() in * 'kernel/power/hibernate' to check if the image is compressed and query * for the compression algorithm support(if so). */unsigned int swsusp_header_flags; static int swsusp_swap_check(void){	int res; 	/*	 * Check if the resume device is a swap device and get its index (if so).	 * This is called before saving the image.	 */	if (swsusp_resume_device)		res = find_hibernation_swap_type(swsusp_resume_device, swsusp_resume_block);	else		res = find_first_swap(&swsusp_resume_device);	if (res < 0)		return res;	root_swap = res; 	hib_resume_bdev_file = bdev_file_open_by_dev(swsusp_resume_device,			BLK_OPEN_WRITE, NULL, NULL);	if (IS_ERR(hib_resume_bdev_file))		return PTR_ERR(hib_resume_bdev_file); 	return 0;} static int write_page(void *buf, sector_t offset, struct hib_bio_batch *hb){	gfp_t gfp = GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY;	void *src;	int ret; 	if (!offset)		return -ENOSPC; 	if (!hb)		goto sync_io; 	src = (void *)__get_free_page(gfp);	if (!src) {		ret = hib_wait_io(hb); /* Free pages */		if (ret)			return ret;		src = (void *)__get_free_page(gfp);		if (WARN_ON_ONCE(!src))			goto sync_io;	} 	copy_page(src, buf);	return hib_submit_io_async(REQ_OP_WRITE | REQ_SYNC, offset, src, hb);sync_io:	return hib_submit_io_sync(REQ_OP_WRITE | REQ_SYNC, offset, buf);} static void release_swap_writer(struct swap_map_handle *handle){	if (handle->cur)		free_page((unsigned long)handle->cur);	handle->cur = NULL;} static int get_swap_writer(struct swap_map_handle *handle){	int ret; 	ret = swsusp_swap_check();	if (ret) {		if (ret != -ENOSPC)			pr_err("Cannot find swap device, try swapon -a\n");		return ret;	}	handle->cur = (struct swap_map_page *)get_zeroed_page(GFP_KERNEL);	if (!handle->cur) {		ret = -ENOMEM;		goto err_close;	}	handle->cur_swap = alloc_swapdev_block(root_swap);	if (!handle->cur_swap) {		ret = -ENOSPC;		goto err_rel;	}	handle->k = 0;	handle->reqd_free_pages = reqd_free_pages();	handle->first_sector = handle->cur_swap;	return 0;err_rel:	release_swap_writer(handle);err_close:	swsusp_close();	return ret;} static int swap_write_page(struct swap_map_handle *handle, void *buf,		struct hib_bio_batch *hb){	int error;	sector_t offset; 	if (!handle->cur)		return -EINVAL; 	/*	 * If the current map page is full, allocate and link next one first.	 * Delaying this until here avoids writing an empty swap map page when	 * the image size is an exact MAP_PAGE_ENTRIES multiple.	 */	if (handle->k >= MAP_PAGE_ENTRIES) {		offset = alloc_swapdev_block(root_swap);		if (!offset)			return -ENOSPC; 		handle->cur->next_swap = offset;		error = write_page(handle->cur, handle->cur_swap, hb);		if (error)			return error; 		clear_page(handle->cur);		handle->cur_swap = offset;		handle->k = 0; 		if (hb && low_free_pages() <= handle->reqd_free_pages) {			error = hib_wait_io(hb);			if (error)				return error;			/*			 * Recalculate the number of required free pages, to			 * make sure we never take more than half.			 */			handle->reqd_free_pages = reqd_free_pages();		}	} 	offset = alloc_swapdev_block(root_swap);	error = write_page(buf, offset, hb);	if (error)		return error;	handle->cur->entries[handle->k++] = offset;	return 0;} static int flush_swap_writer(struct swap_map_handle *handle){	if (handle->cur && handle->cur_swap && handle->k)		return write_page(handle->cur, handle->cur_swap, NULL);	else if (handle->cur && handle->cur_swap)		return 0;	else		return -EINVAL;} static int swap_writer_finish(struct swap_map_handle *handle,		unsigned int flags, int error){	if (!error) {		pr_info("S");		error = mark_swapfiles(handle, flags);		pr_cont("|\n");		flush_swap_writer(handle);	} 	if (error)		free_all_swap_pages(root_swap);	release_swap_writer(handle);	swsusp_close(); 	return error;} 

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