Date:   Tue, 23 Aug 2016 17:45:27 +0800
From:   joeyli <jlee@...e.com>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     rjw@...ysocki.net, pavel@....cz, len.brown@...el.com,
        hpa@...or.com, mingo@...hat.com, tglx@...utronix.de,
        rui.zhang@...el.com, x86@...nel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH][v6] PM / hibernate: Print the possible panic reason when
 resuming with inconsistent e820 map

Hi all, 

On Wed, Oct 21, 2015 at 01:21:40PM +0800, Chen Yu wrote:
> On some platforms, there is occasional panic triggered when trying to
> resume from hibernation, a typical panic looks like:
> 
> "BUG: unable to handle kernel paging request at ffff880085894000
> IP: [<ffffffff810c5dc2>] load_image_lzo+0x8c2/0xe70"
> 
> This is because e820 map has been changed by BIOS before/after
> hibernation, and one of the page frames from first kernel
> is right located in second kernel's unmapped region, so panic
> comes out when accessing unmapped kernel address.
> 
> In order to tell the user why this happeneded, and for scalability,
> we introduce a framework(a new file named hibernation_e820.c) to
> compare the e820 maps before/after hibernation. If these two
> e820 maps are not compatible with each other, we will print
> warning about the first corrupt e820 entry's information
> (there might be more than one broken e820 entries) once the
> system goes into panic, for example:
> 
> BUG: unable to handle kernel paging request at ffff8800a9688000
> IP: [<ffffffff810c5dc2>] load_image_lzo+0x8c2/0xe70
> PM: Hibernation Caution! Oops might be due to inconsistent e820 table.
> PM: mem [0xa963b000-0xa963d000][ACPI Table] is an invalid old e820 region.
> PM: Inconsistent with current [mem 0xa963b000-0xa963e000][ACPI Table].
> PM: Please update your BIOS, or do not use hibernation on this machine.
> 
> The following kind of e820 entries will be regarded as invalid ones:
> 1.E820_RAM:  old region is not a subset of any current region.
> 2.E820_ACPI: old region is not strictly the same as any current
>              region(example above).
> 
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> ---
> v6:
>  - Fix some compiling errors reported by 0day/LKP, adjust
>    Kconfig/variable namings.
> v5:
>  - Rewrite this patch to just warn user of the broken BIOS
>    when panic.
> v4:
>  - Add __attribute__ ((unused)) for swsusp_page_is_valid,
>    to eliminate the warnning of:
>    'swsusp_page_is_valid' defined but not used
>    on non-x86 platforms.
> 
> v3:
>  - Adjust the logic to exclude the end_pfn boundary in pfn_mapped
>    when invoking mark_valid_pages, because the end_pfn is not
>    a mapped page frame, we should not regard it as a valid page.
> 
>    Move the sanity check of valid pages to a early stage in resuming
>    process(moved to mark_unsafe_pages), in this way, we can avoid
>    unnecessarily accessing these invalid pages in later stage(yes,
>    move to the original position Joey once introduced in:
>    Commit 84c91b7ae07c ("PM / hibernate: avoid unsafe pages in e820
>    reserved regions")
> 
>    With v3 patch applied, I did 30 cycles on my problematic platform,
>    no panic triggered anymore(50% reproducible before patched, by
>    plugging/unplugging memory peripheral during hibernation), and it
>    just warns of invalid pages.
>    
> v2:
>  - According to Ingo's suggestion, rewrite this patch.
> 
>    New version just checks each page frame according to pfn_mapped array.
>    So that we do not need to touch existing code related to
>    E820_RESERVED_KERN. And this method can naturely guarantee
>    that the system before/after hibernation do not need to be of
>    the same memory size on x86_64.

What's the progress of this patch? Looks already have experts review it.
Why this patch didn't accept?


Thanks a lot!
Joey Lee

> ---
>  arch/x86/Kconfig                |   1 +
>  arch/x86/power/Makefile         |   2 +-
>  arch/x86/power/hibernate_e820.c | 243 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/suspend.h         |  19 ++++
>  kernel/power/Kconfig            |   4 +
>  kernel/power/power.h            |   8 ++
>  kernel/power/snapshot.c         |   8 ++
>  7 files changed, 284 insertions(+), 1 deletion(-)
>  create mode 100644 arch/x86/power/hibernate_e820.c
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 96d058a..9f72144 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -30,6 +30,7 @@ config X86
>  	select ARCH_HAS_PMEM_API		if X86_64
>  	select ARCH_HAS_MMIO_FLUSH
>  	select ARCH_HAS_SG_CHAIN
> +	select ARCH_HAS_RESUME_IMAGE_CHECKER	if HIBERNATION
>  	select ARCH_HAVE_NMI_SAFE_CMPXCHG
>  	select ARCH_MIGHT_HAVE_ACPI_PDC		if ACPI
>  	select ARCH_MIGHT_HAVE_PC_PARPORT
> diff --git a/arch/x86/power/Makefile b/arch/x86/power/Makefile
> index a6a198c..8877cfb 100644
> --- a/arch/x86/power/Makefile
> +++ b/arch/x86/power/Makefile
> @@ -4,4 +4,4 @@ nostackp := $(call cc-option, -fno-stack-protector)
>  CFLAGS_cpu.o	:= $(nostackp)
>  
>  obj-$(CONFIG_PM_SLEEP)		+= cpu.o
> -obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o
> +obj-$(CONFIG_HIBERNATION)	+= hibernate_$(BITS).o hibernate_asm_$(BITS).o hibernate_e820.o
> diff --git a/arch/x86/power/hibernate_e820.c b/arch/x86/power/hibernate_e820.c
> new file mode 100644
> index 0000000..f51a892
> --- /dev/null
> +++ b/arch/x86/power/hibernate_e820.c
> @@ -0,0 +1,243 @@
> +/*
> + * Hibernation e820 consistence checking for x86.
> + *
> + * Copyright (C) 2015, Intel Corporation
> + * Authors: Chen Yu <yu.c.chen@...el.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/suspend.h>
> +#include <linux/kdebug.h>
> +
> +/*
> + * The following code is to check whether the old e820 map
> + * (system before hibernation) is compatible with current
> + * e820 map(system for resuming).
> + * We check two types of regions: E820_RAM and E820_ACPI,
> + * and to make sure the two kinds of regions will satisfy:
> + * 1. E820_RAM: each old region is a subset of the current ones.
> + * 2. E820_ACPI: each old region is strictly the same as the current ones.
> + *
> + * We save the old e820 map inside the swsusp_info page,
> + * then pass it to the second system for resuming, by the
> + * following format:
> + *
> + *
> + *  +--------+---------+------+------+------+
> + *  | swsusp |e820entry|entry0|entry1|entry2|
> + *  |  info  | number  |      |      |      |
> + *  +--------+---------+------+------+------+
> + *  ^                                                        ^
> + *  |                                                        |
> + *  +--------------struct swsusp_info(PAGE_SIZE)-------------+
> + */
> +
> +/*
> + * Record the first pair of conflicted new/old
> + * e820 entries if there's any.
> + */
> +static u32 bad_old_type;
> +static u64 bad_old_start, bad_old_end;
> +
> +static u32 bad_new_type;
> +static u64 bad_new_start, bad_new_end;
> +
> +/**
> + *	arch_image_info_save - save specified e820 data to
> + *		 the hibernation image header
> + *	@dst: address to save the data to.
> + *	@src: source data need to be saved,
> + *	      if NULL then save current system's e820 map.
> + *	@limit_len: max len in bytes to write.
> + */
> +int arch_image_info_save(char *dst, const char *src, unsigned int limit_len)
> +{
> +	unsigned int nr_e820_map;
> +	unsigned int size_to_copy;
> +	struct e820map *e820_map;
> +
> +	/*
> +	 * The final copied structure is illustrated below:
> +	 * [number_of_e820entry][e820entry0)[e820entry1)...
> +	 */
> +	if (src) {
> +		nr_e820_map = *(unsigned int *)src;
> +		e820_map = (struct e820map *)(src + sizeof(unsigned int));
> +	} else {
> +		nr_e820_map = e820_saved.nr_map;
> +		e820_map = &e820_saved;
> +	}
> +
> +	size_to_copy = nr_e820_map * sizeof(struct e820entry);
> +
> +	if ((size_to_copy + sizeof(unsigned int)) > limit_len) {
> +		pr_warn("PM: Hibernation can not save extra info due to too many e820 entries\n");
> +		return -ENOMEM;
> +	}
> +	*(unsigned int *)dst = nr_e820_map;
> +	dst += sizeof(unsigned int);
> +	memcpy(dst, (void *)&e820_map->map[0], size_to_copy);
> +	return 0;
> +}
> +
> +/**
> + *	arch_image_info_check - check the relationship between
> + *	new and old e820 map, to make sure that, the E820_RAM
> + *	in old e820, is a subset of the new e820 map, and the
> + *	E820_ACPI regions in old e820 map, are strictly the
> + *	same as new e820 map. If it is, return true, otherwise return false.
> + *
> + *	@new: New e820 map address, usually it is the
> + *	      current system's e820_saved.
> + *	@old: Old e820 map address, it is usually the
> + *	      e820 map before hibernation.
> + */
> +bool arch_image_info_check(const char *new, const char *old)
> +{
> +	struct e820map *e820_old, *e820_new;
> +	int i, j, nr_e820_old, nr_e820_new;
> +
> +	e820_old = (struct e820map *)old;
> +	nr_e820_old = *(unsigned int *)e820_old;
> +
> +	if (new)
> +		e820_new = (struct e820map *)new;
> +	else
> +		e820_new = &e820_saved;
> +
> +	nr_e820_new = e820_new->nr_map;
> +
> +	if ((nr_e820_old == 0) || (nr_e820_new == 0) ||
> +		(nr_e820_old > E820_X_MAX) || (nr_e820_new > E820_X_MAX))
> +		return false;
> +
> +	for (i = 0; i < nr_e820_old; i++) {
> +		u64 old_start, old_end;
> +		struct e820entry *ei_old;
> +		bool valid_old_entry = false;
> +
> +		ei_old = &e820_old->map[i];
> +
> +		/*
> +		 * Only check RAM memory and ACPI table regions,
> +		 * and we follow this policy:
> +		 * 1.The old e820 RAM region must be new RAM's subset.
> +		 * 2.The old e820 ACPI table region must be the same
> +		 *   as the new one.
> +		 */
> +		if (ei_old->type != E820_RAM && ei_old->type != E820_ACPI)
> +			continue;
> +
> +		old_start = ei_old->addr;
> +		old_end = ei_old->addr + ei_old->size;
> +
> +		for (j = 0; j < nr_e820_new; j++) {
> +			u64 new_start, new_end;
> +			struct e820entry *ei_new;
> +
> +			if (valid_old_entry)
> +				break;
> +
> +			ei_new = &e820_new->map[i];
> +			new_start = ei_new->addr;
> +			new_end = ei_new->addr + ei_new->size;
> +
> +			/*
> +			 * Check the relationship between these two regions.
> +			 */
> +			if (old_start >= new_start && old_start < new_end) {
> +				   /* Must be of the same type. */
> +				if ((ei_old->type != ei_new->type) ||
> +				   /* E820_RAM must be the subset */
> +				    ((ei_old->type == E820_RAM) &&
> +				     (old_end > new_end)) ||
> +				   /* E820_ACPI must remain unchanged. */
> +				    ((ei_old->type == E820_ACPI) &&
> +				     (old_start != new_start ||
> +						old_end != new_end))) {
> +					bad_old_start = old_start;
> +					bad_old_end = old_end;
> +					bad_old_type = ei_old->type;
> +					bad_new_start = new_start;
> +					bad_new_end = new_end;
> +					bad_new_type = ei_new->type;
> +
> +					return false;
> +				}
> +				/* OK, this one is a valid e820 region. */
> +				valid_old_entry = true;
> +			}
> +		}
> +		/* If we did not find any overlapping between this old e820
> +		 * region and the new regions, return invalid.
> +		 */
> +		if (!valid_old_entry) {
> +			bad_old_start = old_start;
> +			bad_old_end = old_end;
> +			return false;
> +		}
> +	}
> +	/* All the old e820 entries are valid */
> +	return true;
> +}
> +
> +static void e820_dump_map(struct e820map *e820_dump)
> +{
> +	int i;
> +
> +	for (i = 0; i < e820_dump->nr_map; i++) {
> +		printk(KERN_ERR "[mem %#018Lx-%#018Lx] [%d]\n",
> +		       (unsigned long long) e820_dump->map[i].addr,
> +		       (unsigned long long)
> +		       (e820_dump->map[i].addr + e820_dump->map[i].size - 1),
> +			e820_dump->map[i].type);
> +	}
> +}
> +
> +/*
> + * This hook is invoked when kernel dies, and will print the broken e820 map
> + * if it is caused by BIOS memory bug.
> + */
> +static int arch_hibernation_die_check(struct notifier_block *nb,
> +				      unsigned long action,
> +				      void *data)
> +{
> +	if (!bad_old_start || !bad_old_end)
> +		return 0;
> +
> +	pr_err("PM: Hibernation Caution! Oops might be due to inconsistent e820 table.\n");
> +	pr_err("PM: [mem %#010llx-%#010llx][%s] is an invalid old e820 region.\n",
> +			bad_old_start, bad_old_end - 1,
> +			(bad_old_type == E820_RAM) ? "RAM" : "ACPI Table");
> +	if (bad_new_start && bad_new_end)
> +		pr_err("PM: Inconsistent with current [mem %#010llx-%#010llx][%s]\n",
> +			bad_new_start, bad_new_end - 1,
> +			(bad_new_type == E820_RAM) ? "RAM" : "ACPI Table");
> +	pr_err("PM: Please update your BIOS, or do not use hibernation on this machine.\n");
> +	pr_err("PM: Current system's e820 table:\n");
> +	e820_dump_map(&e820_saved);
> +	/* Avoid nested die print*/
> +	bad_old_start = bad_old_end = 0;
> +
> +	return 0;
> +}
> +
> +static struct notifier_block hibernation_notifier = {
> +	.notifier_call = arch_hibernation_die_check,
> +};
> +
> +static int __init arch_init_hibernation(void)
> +{
> +	int retval;
> +
> +	retval = register_die_notifier(&hibernation_notifier);
> +	if (retval)
> +		return retval;
> +
> +	return 0;
> +}
> +
> +late_initcall(arch_init_hibernation);
> diff --git a/include/linux/suspend.h b/include/linux/suspend.h
> index 5efe743..5946b5c 100644
> --- a/include/linux/suspend.h
> +++ b/include/linux/suspend.h
> @@ -361,6 +361,25 @@ static inline bool system_entering_hibernation(void) { return false; }
>  static inline bool hibernation_available(void) { return false; }
>  #endif /* CONFIG_HIBERNATION */
>  
> +#ifdef CONFIG_ARCH_HAS_RESUME_IMAGE_CHECKER
> +extern int arch_image_info_save(char *dst, const char *src,
> +				unsigned int limit_len);
> +extern bool arch_image_info_check(const char *new, const char *old);
> +#else
> +static inline bool arch_image_info_check(const char *new,
> +					 const char *old)
> +{
> +	return true;
> +}
> +
> +static inline int arch_image_info_save(char *dst,
> +					const char *src,
> +					unsigned int limit_len)
> +{
> +	return 0;
> +}
> +#endif
> +
>  /* Hibernation and suspend events */
>  #define PM_HIBERNATION_PREPARE	0x0001 /* Going to hibernate */
>  #define PM_POST_HIBERNATION	0x0002 /* Hibernation finished */
> diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> index 02e8dfa..4d8e6d8 100644
> --- a/kernel/power/Kconfig
> +++ b/kernel/power/Kconfig
> @@ -79,6 +79,10 @@ config HIBERNATION
>  config ARCH_SAVE_PAGE_KEYS
>  	bool
>  
> +config ARCH_HAS_RESUME_IMAGE_CHECKER
> +	bool
> +	depends on HIBERNATION
> +
>  config PM_STD_PARTITION
>  	string "Default resume partition"
>  	depends on HIBERNATION
> diff --git a/kernel/power/power.h b/kernel/power/power.h
> index caadb56..d279907 100644
> --- a/kernel/power/power.h
> +++ b/kernel/power/power.h
> @@ -14,6 +14,14 @@ struct swsusp_info {
>  	unsigned long		size;
>  } __aligned(PAGE_SIZE);
>  
> +/*
> + *  Since struct swsusp_info will take one page size,
> + *  some platforms save the extra data right after the
> + *  last structure element.
> + */
> +#define SWSUSP_INFO_ACTUAL_SIZE \
> +	(offsetof(struct swsusp_info, size) + sizeof(unsigned long))
> +
>  #ifdef CONFIG_HIBERNATION
>  /* kernel/power/snapshot.c */
>  extern void __init hibernate_reserved_size_init(void);
> diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
> index 5235dd4..394d20d 100644
> --- a/kernel/power/snapshot.c
> +++ b/kernel/power/snapshot.c
> @@ -1970,6 +1970,11 @@ int snapshot_read_next(struct snapshot_handle *handle)
>  		error = init_header((struct swsusp_info *)buffer);
>  		if (error)
>  			return error;
> +
> +		arch_image_info_save((char *)buffer + SWSUSP_INFO_ACTUAL_SIZE,
> +				     NULL,
> +				     PAGE_SIZE-SWSUSP_INFO_ACTUAL_SIZE);
> +
>  		handle->buffer = buffer;
>  		memory_bm_position_reset(&orig_bm);
>  		memory_bm_position_reset(&copy_bm);
> @@ -2491,6 +2496,9 @@ int snapshot_write_next(struct snapshot_handle *handle)
>  		if (error)
>  			return error;
>  
> +		arch_image_info_check(NULL,
> +				     (char *)buffer + SWSUSP_INFO_ACTUAL_SIZE);
> +
>  		error = memory_bm_create(&copy_bm, GFP_ATOMIC, PG_ANY);
>  		if (error)
>  			return error;
> -- 
> 1.8.4.2
> 
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