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SubjectRe: [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@intel.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@intel.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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