linux/kernel/power/swsusp.c

1127 lines
26 KiB
C
Raw Normal View History

/*
* linux/kernel/power/swsusp.c
*
* This file is to realize architecture-independent
* machine suspend feature using pretty near only high-level routines
*
* 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
*
* Andreas Steinmetz <ast@domdv.de>:
* Added encrypted suspend option
*
* 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/reboot.h>
#include <linux/bitops.h>
#include <linux/vt_kern.h>
#include <linux/kbd_kern.h>
#include <linux/keyboard.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/console.h>
#include <linux/highmem.h>
#include <linux/bio.h>
#include <linux/mount.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/io.h>
#include <linux/random.h>
#include <linux/crypto.h>
#include <asm/scatterlist.h>
#include "power.h"
#define CIPHER "aes"
#define MAXKEY 32
#define MAXIV 32
extern char resume_file[];
/* Local variables that should not be affected by save */
unsigned int nr_copy_pages __nosavedata = 0;
/* Suspend pagedir is allocated before final copy, therefore it
must be freed after resume
Warning: this is evil. There are actually two pagedirs at time of
resume. One is "pagedir_save", which is empty frame allocated at
time of suspend, that must be freed. Second is "pagedir_nosave",
allocated at time of resume, that travels through memory not to
collide with anything.
Warning: this is even more evil than it seems. Pagedirs this file
talks about are completely different from page directories used by
MMU hardware.
*/
suspend_pagedir_t *pagedir_nosave __nosavedata = NULL;
suspend_pagedir_t *pagedir_save;
#define SWSUSP_SIG "S1SUSPEND"
static struct swsusp_header {
char reserved[PAGE_SIZE - 20 - MAXKEY - MAXIV - sizeof(swp_entry_t)];
u8 key_iv[MAXKEY+MAXIV];
swp_entry_t swsusp_info;
char orig_sig[10];
char sig[10];
} __attribute__((packed, aligned(PAGE_SIZE))) swsusp_header;
static struct swsusp_info swsusp_info;
/*
* Saving part...
*/
/* We memorize in swapfile_used what swap devices are used for suspension */
#define SWAPFILE_UNUSED 0
#define SWAPFILE_SUSPEND 1 /* This is the suspending device */
#define SWAPFILE_IGNORED 2 /* Those are other swap devices ignored for suspension */
static unsigned short swapfile_used[MAX_SWAPFILES];
static unsigned short root_swap;
static int write_page(unsigned long addr, swp_entry_t * loc);
static int bio_read_page(pgoff_t page_off, void * page);
static u8 key_iv[MAXKEY+MAXIV];
#ifdef CONFIG_SWSUSP_ENCRYPT
static int crypto_init(int mode, void **mem)
{
int error = 0;
int len;
char *modemsg;
struct crypto_tfm *tfm;
modemsg = mode ? "suspend not possible" : "resume not possible";
tfm = crypto_alloc_tfm(CIPHER, CRYPTO_TFM_MODE_CBC);
if(!tfm) {
printk(KERN_ERR "swsusp: no tfm, %s\n", modemsg);
error = -EINVAL;
goto out;
}
if(MAXKEY < crypto_tfm_alg_min_keysize(tfm)) {
printk(KERN_ERR "swsusp: key buffer too small, %s\n", modemsg);
error = -ENOKEY;
goto fail;
}
if (mode)
get_random_bytes(key_iv, MAXKEY+MAXIV);
len = crypto_tfm_alg_max_keysize(tfm);
if (len > MAXKEY)
len = MAXKEY;
if (crypto_cipher_setkey(tfm, key_iv, len)) {
printk(KERN_ERR "swsusp: key setup failure, %s\n", modemsg);
error = -EKEYREJECTED;
goto fail;
}
len = crypto_tfm_alg_ivsize(tfm);
if (MAXIV < len) {
printk(KERN_ERR "swsusp: iv buffer too small, %s\n", modemsg);
error = -EOVERFLOW;
goto fail;
}
crypto_cipher_set_iv(tfm, key_iv+MAXKEY, len);
*mem=(void *)tfm;
goto out;
fail: crypto_free_tfm(tfm);
out: return error;
}
static __inline__ void crypto_exit(void *mem)
{
crypto_free_tfm((struct crypto_tfm *)mem);
}
static __inline__ int crypto_write(struct pbe *p, void *mem)
{
int error = 0;
struct scatterlist src, dst;
src.page = virt_to_page(p->address);
src.offset = 0;
src.length = PAGE_SIZE;
dst.page = virt_to_page((void *)&swsusp_header);
dst.offset = 0;
dst.length = PAGE_SIZE;
error = crypto_cipher_encrypt((struct crypto_tfm *)mem, &dst, &src,
PAGE_SIZE);
if (!error)
error = write_page((unsigned long)&swsusp_header,
&(p->swap_address));
return error;
}
static __inline__ int crypto_read(struct pbe *p, void *mem)
{
int error = 0;
struct scatterlist src, dst;
error = bio_read_page(swp_offset(p->swap_address), (void *)p->address);
if (!error) {
src.offset = 0;
src.length = PAGE_SIZE;
dst.offset = 0;
dst.length = PAGE_SIZE;
src.page = dst.page = virt_to_page((void *)p->address);
error = crypto_cipher_decrypt((struct crypto_tfm *)mem, &dst,
&src, PAGE_SIZE);
}
return error;
}
#else
static __inline__ int crypto_init(int mode, void *mem)
{
return 0;
}
static __inline__ void crypto_exit(void *mem)
{
}
static __inline__ int crypto_write(struct pbe *p, void *mem)
{
return write_page(p->address, &(p->swap_address));
}
static __inline__ int crypto_read(struct pbe *p, void *mem)
{
return bio_read_page(swp_offset(p->swap_address), (void *)p->address);
}
#endif
static int mark_swapfiles(swp_entry_t prev)
{
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);
memcpy(swsusp_header.key_iv, key_iv, MAXKEY+MAXIV);
swsusp_header.swsusp_info = prev;
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 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, len;
len=strlen(resume_file);
root_swap = 0xFFFF;
spin_lock(&swap_lock);
for (i=0; i<MAX_SWAPFILES; i++) {
if (!(swap_info[i].flags & SWP_WRITEOK)) {
swapfile_used[i]=SWAPFILE_UNUSED;
} else {
if (!len) {
printk(KERN_WARNING "resume= option should be used to set suspend device" );
if (root_swap == 0xFFFF) {
swapfile_used[i] = SWAPFILE_SUSPEND;
root_swap = i;
} else
swapfile_used[i] = SWAPFILE_IGNORED;
} else {
/* we ignore all swap devices that are not the resume_file */
if (is_resume_device(&swap_info[i])) {
swapfile_used[i] = SWAPFILE_SUSPEND;
root_swap = i;
} else {
swapfile_used[i] = SWAPFILE_IGNORED;
}
}
}
}
spin_unlock(&swap_lock);
return (root_swap != 0xffff) ? 0 : -ENODEV;
}
/**
* This is called after saving image so modification
* will be lost after resume... and that's what we want.
* we make the device unusable. A new call to
* lock_swapdevices can unlock the devices.
*/
static void lock_swapdevices(void)
{
int i;
spin_lock(&swap_lock);
for (i = 0; i< MAX_SWAPFILES; i++)
if (swapfile_used[i] == SWAPFILE_IGNORED) {
swap_info[i].flags ^= SWP_WRITEOK;
}
spin_unlock(&swap_lock);
}
/**
* 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.
* This is a partial improvement, since we will at least return other
* errors, though we need to eventually fix the damn code.
*/
static int write_page(unsigned long addr, swp_entry_t * loc)
{
swp_entry_t entry;
int error = 0;
entry = get_swap_page();
if (swp_offset(entry) &&
swapfile_used[swp_type(entry)] == SWAPFILE_SUSPEND) {
error = rw_swap_page_sync(WRITE, entry,
virt_to_page(addr));
if (error == -EIO)
error = 0;
if (!error)
*loc = entry;
} else
error = -ENOSPC;
return error;
}
/**
* data_free - Free the swap entries used by the saved image.
*
* Walk the list of used swap entries and free each one.
* This is only used for cleanup when suspend fails.
*/
static void data_free(void)
{
swp_entry_t entry;
struct pbe * p;
for_each_pbe(p, pagedir_nosave) {
entry = p->swap_address;
if (entry.val)
swap_free(entry);
else
break;
}
}
/**
* data_write - Write saved image to swap.
*
* Walk the list of pages in the image and sync each one to swap.
*/
static int data_write(void)
{
int error = 0, i = 0;
unsigned int mod = nr_copy_pages / 100;
struct pbe *p;
void *tfm;
if ((error = crypto_init(1, &tfm)))
return error;
if (!mod)
mod = 1;
printk( "Writing data to swap (%d pages)... ", nr_copy_pages );
for_each_pbe (p, pagedir_nosave) {
if (!(i%mod))
printk( "\b\b\b\b%3d%%", i / mod );
if ((error = crypto_write(p, tfm))) {
crypto_exit(tfm);
return error;
}
i++;
}
printk("\b\b\b\bdone\n");
crypto_exit(tfm);
return error;
}
static void dump_info(void)
{
pr_debug(" swsusp: Version: %u\n",swsusp_info.version_code);
pr_debug(" swsusp: Num Pages: %ld\n",swsusp_info.num_physpages);
pr_debug(" swsusp: UTS Sys: %s\n",swsusp_info.uts.sysname);
pr_debug(" swsusp: UTS Node: %s\n",swsusp_info.uts.nodename);
pr_debug(" swsusp: UTS Release: %s\n",swsusp_info.uts.release);
pr_debug(" swsusp: UTS Version: %s\n",swsusp_info.uts.version);
pr_debug(" swsusp: UTS Machine: %s\n",swsusp_info.uts.machine);
pr_debug(" swsusp: UTS Domain: %s\n",swsusp_info.uts.domainname);
pr_debug(" swsusp: CPUs: %d\n",swsusp_info.cpus);
pr_debug(" swsusp: Image: %ld Pages\n",swsusp_info.image_pages);
pr_debug(" swsusp: Pagedir: %ld Pages\n",swsusp_info.pagedir_pages);
}
static void init_header(void)
{
memset(&swsusp_info, 0, sizeof(swsusp_info));
swsusp_info.version_code = LINUX_VERSION_CODE;
swsusp_info.num_physpages = num_physpages;
memcpy(&swsusp_info.uts, &system_utsname, sizeof(system_utsname));
swsusp_info.suspend_pagedir = pagedir_nosave;
swsusp_info.cpus = num_online_cpus();
swsusp_info.image_pages = nr_copy_pages;
}
static int close_swap(void)
{
swp_entry_t entry;
int error;
dump_info();
error = write_page((unsigned long)&swsusp_info, &entry);
if (!error) {
printk( "S" );
error = mark_swapfiles(entry);
printk( "|\n" );
}
return error;
}
/**
* free_pagedir_entries - Free pages used by the page directory.
*
* This is used during suspend for error recovery.
*/
static void free_pagedir_entries(void)
{
int i;
for (i = 0; i < swsusp_info.pagedir_pages; i++)
swap_free(swsusp_info.pagedir[i]);
}
/**
* write_pagedir - Write the array of pages holding the page directory.
* @last: Last swap entry we write (needed for header).
*/
static int write_pagedir(void)
{
int error = 0;
unsigned n = 0;
struct pbe * pbe;
printk( "Writing pagedir...");
for_each_pb_page (pbe, pagedir_nosave) {
if ((error = write_page((unsigned long)pbe, &swsusp_info.pagedir[n++])))
return error;
}
swsusp_info.pagedir_pages = n;
printk("done (%u pages)\n", n);
return error;
}
/**
* write_suspend_image - Write entire image and metadata.
*
*/
static int write_suspend_image(void)
{
int error;
init_header();
if ((error = data_write()))
goto FreeData;
if ((error = write_pagedir()))
goto FreePagedir;
if ((error = close_swap()))
goto FreePagedir;
Done:
memset(key_iv, 0, MAXKEY+MAXIV);
return error;
FreePagedir:
free_pagedir_entries();
FreeData:
data_free();
goto Done;
}
/**
* enough_swap - Make sure we have enough swap to save the image.
*
* Returns TRUE or FALSE after checking the total amount of swap
* space avaiable.
*
* FIXME: si_swapinfo(&i) returns all swap devices information.
* We should only consider resume_device.
*/
int enough_swap(unsigned nr_pages)
{
struct sysinfo i;
si_swapinfo(&i);
pr_debug("swsusp: available swap: %lu pages\n", i.freeswap);
return i.freeswap > (nr_pages + PAGES_FOR_IO +
(nr_pages + PBES_PER_PAGE - 1) / PBES_PER_PAGE);
}
/* It is important _NOT_ to umount filesystems at this point. We want
* them synced (in case something goes wrong) but we DO not want to mark
* filesystem clean: it is not. (And it does not matter, if we resume
* correctly, we'll mark system clean, anyway.)
*/
int swsusp_write(void)
{
int error;
device_resume();
lock_swapdevices();
error = write_suspend_image();
/* This will unlock ignored swap devices since writing is finished */
lock_swapdevices();
return error;
}
int swsusp_suspend(void)
{
int error;
if ((error = arch_prepare_suspend()))
return error;
local_irq_disable();
/* At this point, device_suspend() has been called, but *not*
* device_power_down(). We *must* device_power_down() now.
* Otherwise, drivers for some devices (e.g. interrupt controllers)
* become desynchronized with the actual state of the hardware
* at resume time, and evil weirdness ensues.
*/
if ((error = device_power_down(PMSG_FREEZE))) {
printk(KERN_ERR "Some devices failed to power down, aborting suspend\n");
local_irq_enable();
return error;
}
if ((error = swsusp_swap_check())) {
printk(KERN_ERR "swsusp: cannot find swap device, try swapon -a.\n");
device_power_up();
local_irq_enable();
return error;
}
save_processor_state();
if ((error = swsusp_arch_suspend()))
printk(KERN_ERR "Error %d suspending\n", error);
/* Restore control flow magically appears here */
restore_processor_state();
restore_highmem();
device_power_up();
local_irq_enable();
return error;
}
int swsusp_resume(void)
{
int error;
local_irq_disable();
if (device_power_down(PMSG_FREEZE))
printk(KERN_ERR "Some devices failed to power down, very bad\n");
/* We'll ignore saved state, but this gets preempt count (etc) right */
save_processor_state();
error = swsusp_arch_resume();
/* Code below is only ever reached in case of failure. Otherwise
* execution continues at place where swsusp_arch_suspend was called
*/
BUG_ON(!error);
restore_processor_state();
restore_highmem();
touch_softlockup_watchdog();
device_power_up();
local_irq_enable();
return error;
}
/**
* On resume, for storing the PBE list and the image,
* we can only use memory pages that do not conflict with the pages
* which had been used before suspend.
*
* We don't know which pages are usable until we allocate them.
*
* Allocated but unusable (ie eaten) memory pages are linked together
* to create a list, so that we can free them easily
*
* We could have used a type other than (void *)
* for this purpose, but ...
*/
static void **eaten_memory = NULL;
static inline void eat_page(void *page)
{
void **c;
c = eaten_memory;
eaten_memory = page;
*eaten_memory = c;
}
unsigned long get_usable_page(gfp_t gfp_mask)
{
unsigned long m;
m = get_zeroed_page(gfp_mask);
while (!PageNosaveFree(virt_to_page(m))) {
eat_page((void *)m);
m = get_zeroed_page(gfp_mask);
if (!m)
break;
}
return m;
}
[PATCH] x86_64: Set up safe page tables during resume The following patch makes swsusp avoid the possible temporary corruption of page translation tables during resume on x86-64. This is achieved by creating a copy of the relevant page tables that will not be modified by swsusp and can be safely used by it on resume. The problem is that during resume on x86-64 swsusp may temporarily corrupt the page tables used for the direct mapping of RAM. If that happens, a page fault occurs and cannot be handled properly, which leads to the solid hang of the affected system. This leads to the loss of the system's state from before suspend and may result in the loss of data or the corruption of filesystems, so it is a serious issue. Also, it appears to happen quite often (for me, as often as 50% of the time). The problem is related to the fact that (at least) one of the PMD entries used in the direct memory mapping (starting at PAGE_OFFSET) points to a page table the physical address of which is much greater than the physical address of the PMD entry itself. Moreover, unfortunately, the physical address of the page table before suspend (i.e. the one stored in the suspend image) happens to be different to the physical address of the corresponding page table used during resume (i.e. the one that is valid right before swsusp_arch_resume() in arch/x86_64/kernel/suspend_asm.S is executed). Thus while the image is restored, the "offending" PMD entry gets overwritten, so it does not point to the right physical address any more (i.e. there's no page table at the address pointed to by it, because it points to the address the page table has been at during suspend). Consequently, if the PMD entry is used later on, and it _is_ used in the process of copying the image pages, a page fault occurs, but it cannot be handled in the normal way and the system hangs. In principle we can call create_resume_mapping() from swsusp_arch_resume() (ie. from suspend_asm.S), but then the memory allocations in create_resume_mapping(), resume_pud_mapping(), and resume_pmd_mapping() must be made carefully so that we use _only_ NosaveFree pages in them (the other pages are overwritten by the loop in swsusp_arch_resume()). Additionally, we are in atomic context at that time, so we cannot use GFP_KERNEL. Moreover, if one of the allocations fails, we should free all of the allocated pages, so we need to trace them somehow. All of this is done in the appended patch, except that the functions populating the page tables are located in arch/x86_64/kernel/suspend.c rather than in init.c. It may be done in a more elegan way in the future, with the help of some swsusp patches that are in the works now. [AK: move some externs into headers, renamed a function] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-09 19:19:40 +00:00
void free_eaten_memory(void)
{
unsigned long m;
void **c;
int i = 0;
c = eaten_memory;
while (c) {
m = (unsigned long)c;
c = *c;
free_page(m);
i++;
}
eaten_memory = NULL;
pr_debug("swsusp: %d unused pages freed\n", i);
}
/**
* check_pagedir - We ensure here that pages that the PBEs point to
* won't collide with pages where we're going to restore from the loaded
* pages later
*/
static int check_pagedir(struct pbe *pblist)
{
struct pbe *p;
/* This is necessary, so that we can free allocated pages
* in case of failure
*/
for_each_pbe (p, pblist)
p->address = 0UL;
for_each_pbe (p, pblist) {
p->address = get_usable_page(GFP_ATOMIC);
if (!p->address)
return -ENOMEM;
}
return 0;
}
/**
* swsusp_pagedir_relocate - It is possible, that some memory pages
* occupied by the list of PBEs collide with pages where we're going to
* restore from the loaded pages later. We relocate them here.
*/
static struct pbe * swsusp_pagedir_relocate(struct pbe *pblist)
{
struct zone *zone;
unsigned long zone_pfn;
struct pbe *pbpage, *tail, *p;
void *m;
int rel = 0, error = 0;
if (!pblist) /* a sanity check */
return NULL;
pr_debug("swsusp: Relocating pagedir (%lu pages to check)\n",
swsusp_info.pagedir_pages);
/* Set page flags */
for_each_zone (zone) {
for (zone_pfn = 0; zone_pfn < zone->spanned_pages; ++zone_pfn)
SetPageNosaveFree(pfn_to_page(zone_pfn +
zone->zone_start_pfn));
}
/* Clear orig addresses */
for_each_pbe (p, pblist)
ClearPageNosaveFree(virt_to_page(p->orig_address));
tail = pblist + PB_PAGE_SKIP;
/* Relocate colliding pages */
for_each_pb_page (pbpage, pblist) {
if (!PageNosaveFree(virt_to_page((unsigned long)pbpage))) {
m = (void *)get_usable_page(GFP_ATOMIC | __GFP_COLD);
if (!m) {
error = -ENOMEM;
break;
}
memcpy(m, (void *)pbpage, PAGE_SIZE);
if (pbpage == pblist)
pblist = (struct pbe *)m;
else
tail->next = (struct pbe *)m;
eat_page((void *)pbpage);
pbpage = (struct pbe *)m;
/* We have to link the PBEs again */
for (p = pbpage; p < pbpage + PB_PAGE_SKIP; p++)
if (p->next) /* needed to save the end */
p->next = p + 1;
rel++;
}
tail = pbpage + PB_PAGE_SKIP;
}
if (error) {
printk("\nswsusp: Out of memory\n\n");
free_pagedir(pblist);
free_eaten_memory();
pblist = NULL;
/* Is this even worth handling? It should never ever happen, and we
have just lost user's state, anyway... */
} else
printk("swsusp: Relocated %d pages\n", rel);
return pblist;
}
[PATCH] DocBook: changes and extensions to the kernel documentation I have recompiled Linux kernel 2.6.11.5 documentation for me and our university students again. The documentation could be extended for more sources which are equipped by structured comments for recent 2.6 kernels. I have tried to proceed with that task. I have done that more times from 2.6.0 time and it gets boring to do same changes again and again. Linux kernel compiles after changes for i386 and ARM targets. I have added references to some more files into kernel-api book, I have added some section names as well. So please, check that changes do not break something and that categories are not too much skewed. I have changed kernel-doc to accept "fastcall" and "asmlinkage" words reserved by kernel convention. Most of the other changes are modifications in the comments to make kernel-doc happy, accept some parameters description and do not bail out on errors. Changed <pid> to @pid in the description, moved some #ifdef before comments to correct function to comments bindings, etc. You can see result of the modified documentation build at http://cmp.felk.cvut.cz/~pisa/linux/lkdb-2.6.11.tar.gz Some more sources are ready to be included into kernel-doc generated documentation. Sources has been added into kernel-api for now. Some more section names added and probably some more chaos introduced as result of quick cleanup work. Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz> Signed-off-by: Martin Waitz <tali@admingilde.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 15:59:25 +00:00
/*
* Using bio to read from swap.
* This code requires a bit more work than just using buffer heads
* but, it is the recommended way for 2.5/2.6.
* The following are to signal the beginning and end of I/O. Bios
* finish asynchronously, while we want them to happen synchronously.
* A simple atomic_t, and a wait loop take care of this problem.
*/
static atomic_t io_done = ATOMIC_INIT(0);
static int end_io(struct bio * bio, unsigned int num, int err)
{
if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
panic("I/O error reading memory image");
atomic_set(&io_done, 0);
return 0;
}
static struct block_device * resume_bdev;
/**
* submit - submit BIO request.
* @rw: READ or WRITE.
* @off physical offset of page.
* @page: page we're reading or writing.
*
* Straight from the textbook - allocate and initialize the bio.
* If we're writing, make sure the page is marked as dirty.
* Then submit it and wait.
*/
static int submit(int rw, pgoff_t page_off, void * page)
{
int error = 0;
struct bio * bio;
bio = bio_alloc(GFP_ATOMIC, 1);
if (!bio)
return -ENOMEM;
bio->bi_sector = page_off * (PAGE_SIZE >> 9);
bio_get(bio);
bio->bi_bdev = resume_bdev;
bio->bi_end_io = end_io;
if (bio_add_page(bio, virt_to_page(page), PAGE_SIZE, 0) < PAGE_SIZE) {
printk("swsusp: ERROR: adding page to bio at %ld\n",page_off);
error = -EFAULT;
goto Done;
}
if (rw == WRITE)
bio_set_pages_dirty(bio);
atomic_set(&io_done, 1);
submit_bio(rw | (1 << BIO_RW_SYNC), bio);
while (atomic_read(&io_done))
yield();
Done:
bio_put(bio);
return error;
}
static int bio_read_page(pgoff_t page_off, void * page)
{
return submit(READ, page_off, page);
}
static int bio_write_page(pgoff_t page_off, void * page)
{
return submit(WRITE, page_off, page);
}
/*
* Sanity check if this image makes sense with this kernel/swap context
* I really don't think that it's foolproof but more than nothing..
*/
static const char * sanity_check(void)
{
dump_info();
if (swsusp_info.version_code != LINUX_VERSION_CODE)
return "kernel version";
if (swsusp_info.num_physpages != num_physpages)
return "memory size";
if (strcmp(swsusp_info.uts.sysname,system_utsname.sysname))
return "system type";
if (strcmp(swsusp_info.uts.release,system_utsname.release))
return "kernel release";
if (strcmp(swsusp_info.uts.version,system_utsname.version))
return "version";
if (strcmp(swsusp_info.uts.machine,system_utsname.machine))
return "machine";
#if 0
/* We can't use number of online CPUs when we use hotplug to remove them ;-))) */
if (swsusp_info.cpus != num_possible_cpus())
return "number of cpus";
#endif
return NULL;
}
static int check_header(void)
{
const char * reason = NULL;
int error;
if ((error = bio_read_page(swp_offset(swsusp_header.swsusp_info), &swsusp_info)))
return error;
/* Is this same machine? */
if ((reason = sanity_check())) {
printk(KERN_ERR "swsusp: Resume mismatch: %s\n",reason);
return -EPERM;
}
nr_copy_pages = swsusp_info.image_pages;
return error;
}
static int check_sig(void)
{
int error;
memset(&swsusp_header, 0, sizeof(swsusp_header));
if ((error = bio_read_page(0, &swsusp_header)))
return error;
if (!memcmp(SWSUSP_SIG, swsusp_header.sig, 10)) {
memcpy(swsusp_header.sig, swsusp_header.orig_sig, 10);
memcpy(key_iv, swsusp_header.key_iv, MAXKEY+MAXIV);
memset(swsusp_header.key_iv, 0, MAXKEY+MAXIV);
/*
* Reset swap signature now.
*/
error = bio_write_page(0, &swsusp_header);
} else {
return -EINVAL;
}
if (!error)
pr_debug("swsusp: Signature found, resuming\n");
return error;
}
/**
* data_read - Read image pages from swap.
*
* You do not need to check for overlaps, check_pagedir()
* already did that.
*/
static int data_read(struct pbe *pblist)
{
struct pbe * p;
int error = 0;
int i = 0;
int mod = swsusp_info.image_pages / 100;
void *tfm;
if ((error = crypto_init(0, &tfm)))
return error;
if (!mod)
mod = 1;
printk("swsusp: Reading image data (%lu pages): ",
swsusp_info.image_pages);
for_each_pbe (p, pblist) {
if (!(i % mod))
printk("\b\b\b\b%3d%%", i / mod);
if ((error = crypto_read(p, tfm))) {
crypto_exit(tfm);
return error;
}
i++;
}
printk("\b\b\b\bdone\n");
crypto_exit(tfm);
return error;
}
/**
* read_pagedir - Read page backup list pages from swap
*/
static int read_pagedir(struct pbe *pblist)
{
struct pbe *pbpage, *p;
unsigned i = 0;
int error;
if (!pblist)
return -EFAULT;
printk("swsusp: Reading pagedir (%lu pages)\n",
swsusp_info.pagedir_pages);
for_each_pb_page (pbpage, pblist) {
unsigned long offset = swp_offset(swsusp_info.pagedir[i++]);
error = -EFAULT;
if (offset) {
p = (pbpage + PB_PAGE_SKIP)->next;
error = bio_read_page(offset, (void *)pbpage);
(pbpage + PB_PAGE_SKIP)->next = p;
}
if (error)
break;
}
if (error)
free_pagedir(pblist);
else
BUG_ON(i != swsusp_info.pagedir_pages);
return error;
}
static int check_suspend_image(void)
{
int error = 0;
if ((error = check_sig()))
return error;
if ((error = check_header()))
return error;
return 0;
}
static int read_suspend_image(void)
{
int error = 0;
struct pbe *p;
if (!(p = alloc_pagedir(nr_copy_pages)))
return -ENOMEM;
if ((error = read_pagedir(p)))
return error;
create_pbe_list(p, nr_copy_pages);
if (!(pagedir_nosave = swsusp_pagedir_relocate(p)))
return -ENOMEM;
/* Allocate memory for the image and read the data from swap */
error = check_pagedir(pagedir_nosave);
[PATCH] x86_64: Set up safe page tables during resume The following patch makes swsusp avoid the possible temporary corruption of page translation tables during resume on x86-64. This is achieved by creating a copy of the relevant page tables that will not be modified by swsusp and can be safely used by it on resume. The problem is that during resume on x86-64 swsusp may temporarily corrupt the page tables used for the direct mapping of RAM. If that happens, a page fault occurs and cannot be handled properly, which leads to the solid hang of the affected system. This leads to the loss of the system's state from before suspend and may result in the loss of data or the corruption of filesystems, so it is a serious issue. Also, it appears to happen quite often (for me, as often as 50% of the time). The problem is related to the fact that (at least) one of the PMD entries used in the direct memory mapping (starting at PAGE_OFFSET) points to a page table the physical address of which is much greater than the physical address of the PMD entry itself. Moreover, unfortunately, the physical address of the page table before suspend (i.e. the one stored in the suspend image) happens to be different to the physical address of the corresponding page table used during resume (i.e. the one that is valid right before swsusp_arch_resume() in arch/x86_64/kernel/suspend_asm.S is executed). Thus while the image is restored, the "offending" PMD entry gets overwritten, so it does not point to the right physical address any more (i.e. there's no page table at the address pointed to by it, because it points to the address the page table has been at during suspend). Consequently, if the PMD entry is used later on, and it _is_ used in the process of copying the image pages, a page fault occurs, but it cannot be handled in the normal way and the system hangs. In principle we can call create_resume_mapping() from swsusp_arch_resume() (ie. from suspend_asm.S), but then the memory allocations in create_resume_mapping(), resume_pud_mapping(), and resume_pmd_mapping() must be made carefully so that we use _only_ NosaveFree pages in them (the other pages are overwritten by the loop in swsusp_arch_resume()). Additionally, we are in atomic context at that time, so we cannot use GFP_KERNEL. Moreover, if one of the allocations fails, we should free all of the allocated pages, so we need to trace them somehow. All of this is done in the appended patch, except that the functions populating the page tables are located in arch/x86_64/kernel/suspend.c rather than in init.c. It may be done in a more elegan way in the future, with the help of some swsusp patches that are in the works now. [AK: move some externs into headers, renamed a function] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-09 19:19:40 +00:00
if (!error)
error = data_read(pagedir_nosave);
if (error) { /* We fail cleanly */
[PATCH] x86_64: Set up safe page tables during resume The following patch makes swsusp avoid the possible temporary corruption of page translation tables during resume on x86-64. This is achieved by creating a copy of the relevant page tables that will not be modified by swsusp and can be safely used by it on resume. The problem is that during resume on x86-64 swsusp may temporarily corrupt the page tables used for the direct mapping of RAM. If that happens, a page fault occurs and cannot be handled properly, which leads to the solid hang of the affected system. This leads to the loss of the system's state from before suspend and may result in the loss of data or the corruption of filesystems, so it is a serious issue. Also, it appears to happen quite often (for me, as often as 50% of the time). The problem is related to the fact that (at least) one of the PMD entries used in the direct memory mapping (starting at PAGE_OFFSET) points to a page table the physical address of which is much greater than the physical address of the PMD entry itself. Moreover, unfortunately, the physical address of the page table before suspend (i.e. the one stored in the suspend image) happens to be different to the physical address of the corresponding page table used during resume (i.e. the one that is valid right before swsusp_arch_resume() in arch/x86_64/kernel/suspend_asm.S is executed). Thus while the image is restored, the "offending" PMD entry gets overwritten, so it does not point to the right physical address any more (i.e. there's no page table at the address pointed to by it, because it points to the address the page table has been at during suspend). Consequently, if the PMD entry is used later on, and it _is_ used in the process of copying the image pages, a page fault occurs, but it cannot be handled in the normal way and the system hangs. In principle we can call create_resume_mapping() from swsusp_arch_resume() (ie. from suspend_asm.S), but then the memory allocations in create_resume_mapping(), resume_pud_mapping(), and resume_pmd_mapping() must be made carefully so that we use _only_ NosaveFree pages in them (the other pages are overwritten by the loop in swsusp_arch_resume()). Additionally, we are in atomic context at that time, so we cannot use GFP_KERNEL. Moreover, if one of the allocations fails, we should free all of the allocated pages, so we need to trace them somehow. All of this is done in the appended patch, except that the functions populating the page tables are located in arch/x86_64/kernel/suspend.c rather than in init.c. It may be done in a more elegan way in the future, with the help of some swsusp patches that are in the works now. [AK: move some externs into headers, renamed a function] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-09 19:19:40 +00:00
free_eaten_memory();
for_each_pbe (p, pagedir_nosave)
if (p->address) {
free_page(p->address);
p->address = 0UL;
}
free_pagedir(pagedir_nosave);
}
return error;
}
/**
* swsusp_check - Check for saved image in swap
*/
int swsusp_check(void)
{
int error;
resume_bdev = open_by_devnum(swsusp_resume_device, FMODE_READ);
if (!IS_ERR(resume_bdev)) {
set_blocksize(resume_bdev, PAGE_SIZE);
error = check_suspend_image();
if (error)
blkdev_put(resume_bdev);
} else
error = PTR_ERR(resume_bdev);
if (!error)
pr_debug("swsusp: resume file found\n");
else
pr_debug("swsusp: Error %d check for resume file\n", error);
return error;
}
/**
* swsusp_read - Read saved image from swap.
*/
int swsusp_read(void)
{
int error;
if (IS_ERR(resume_bdev)) {
pr_debug("swsusp: block device not initialised\n");
return PTR_ERR(resume_bdev);
}
error = read_suspend_image();
blkdev_put(resume_bdev);
memset(key_iv, 0, MAXKEY+MAXIV);
if (!error)
pr_debug("swsusp: Reading resume file was successful\n");
else
pr_debug("swsusp: Error %d resuming\n", error);
return error;
}
/**
* swsusp_close - close swap device.
*/
void swsusp_close(void)
{
if (IS_ERR(resume_bdev)) {
pr_debug("swsusp: block device not initialised\n");
return;
}
blkdev_put(resume_bdev);
}