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kernel_optimize_test/kernel/power/power.h
Rafael J. Wysocki 406f992e4a x86 / hibernate: Use hlt_play_dead() when resuming from hibernation 
On Intel hardware, native_play_dead() uses mwait_play_dead() by
default and only falls back to the other methods if that fails.
That also happens during resume from hibernation, when the restore
(boot) kernel runs disable_nonboot_cpus() to take all of the CPUs
except for the boot one offline.

However, that is problematic, because the address passed to
__monitor() in mwait_play_dead() is likely to be written to in the
last phase of hibernate image restoration and that causes the "dead"
CPU to start executing instructions again.  Unfortunately, the page
containing the address in that CPU's instruction pointer may not be
valid any more at that point.

First, that page may have been overwritten with image kernel memory
contents already, so the instructions the CPU attempts to execute may
simply be invalid.  Second, the page tables previously used by that
CPU may have been overwritten by image kernel memory contents, so the
address in its instruction pointer is impossible to resolve then.

A report from Varun Koyyalagunta and investigation carried out by
Chen Yu show that the latter sometimes happens in practice.

To prevent it from happening, temporarily change the smp_ops.play_dead
pointer during resume from hibernation so that it points to a special
"play dead" routine which uses hlt_play_dead() and avoids the
inadvertent "revivals" of "dead" CPUs this way.

A slightly unpleasant consequence of this change is that if the
system is hibernated with one or more CPUs offline, it will generally
draw more power after resume than it did before hibernation, because
the physical state entered by CPUs via hlt_play_dead() is higher-power
than the mwait_play_dead() one in the majority of cases.  It is
possible to work around this, but it is unclear how much of a problem
that's going to be in practice, so the workaround will be implemented
later if it turns out to be necessary.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=106371
Reported-by: Varun Koyyalagunta <cpudebug@centtech.com>
Original-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
2016-07-15 22:42:48 +02:00

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#include <linux/suspend.h>
#include <linux/suspend_ioctls.h>
#include <linux/utsname.h>
#include <linux/freezer.h>
#include <linux/compiler.h>
struct swsusp_info {
struct new_utsname uts;
u32 version_code;
unsigned long num_physpages;
int cpus;
unsigned long image_pages;
unsigned long pages;
unsigned long size;
} __aligned(PAGE_SIZE);
#ifdef CONFIG_HIBERNATION
/* kernel/power/snapshot.c */
extern void __init hibernate_reserved_size_init(void);
extern void __init hibernate_image_size_init(void);
#ifdef CONFIG_ARCH_HIBERNATION_HEADER
/* Maximum size of architecture specific data in a hibernation header */
#define MAX_ARCH_HEADER_SIZE (sizeof(struct new_utsname) + 4)
extern int arch_hibernation_header_save(void *addr, unsigned int max_size);
extern int arch_hibernation_header_restore(void *addr);
static inline int init_header_complete(struct swsusp_info *info)
{
return arch_hibernation_header_save(info, MAX_ARCH_HEADER_SIZE);
}
static inline char *check_image_kernel(struct swsusp_info *info)
{
return arch_hibernation_header_restore(info) ?
"architecture specific data" : NULL;
}
#endif /* CONFIG_ARCH_HIBERNATION_HEADER */
extern int hibernate_resume_nonboot_cpu_disable(void);
/*
* Keep some memory free so that I/O operations can succeed without paging
* [Might this be more than 4 MB?]
*/
#define PAGES_FOR_IO ((4096 * 1024) >> PAGE_SHIFT)
/*
* Keep 1 MB of memory free so that device drivers can allocate some pages in
* their .suspend() routines without breaking the suspend to disk.
*/
#define SPARE_PAGES ((1024 * 1024) >> PAGE_SHIFT)
asmlinkage int swsusp_save(void);
/* kernel/power/hibernate.c */
extern bool freezer_test_done;
extern int hibernation_snapshot(int platform_mode);
extern int hibernation_restore(int platform_mode);
extern int hibernation_platform_enter(void);
#ifdef CONFIG_DEBUG_RODATA
/* kernel/power/snapshot.c */
extern void enable_restore_image_protection(void);
#else
static inline void enable_restore_image_protection(void) {}
#endif /* CONFIG_DEBUG_RODATA */
#else /* !CONFIG_HIBERNATION */
static inline void hibernate_reserved_size_init(void) {}
static inline void hibernate_image_size_init(void) {}
#endif /* !CONFIG_HIBERNATION */
extern int pfn_is_nosave(unsigned long);
#define power_attr(_name) \
static struct kobj_attribute _name##_attr = { \
.attr = { \
.name = __stringify(_name), \
.mode = 0644, \
}, \
.show = _name##_show, \
.store = _name##_store, \
}
#define power_attr_ro(_name) \
static struct kobj_attribute _name##_attr = { \
.attr = { \
.name = __stringify(_name), \
.mode = S_IRUGO, \
}, \
.show = _name##_show, \
}
/* Preferred image size in bytes (default 500 MB) */
extern unsigned long image_size;
/* Size of memory reserved for drivers (default SPARE_PAGES x PAGE_SIZE) */
extern unsigned long reserved_size;
extern int in_suspend;
extern dev_t swsusp_resume_device;
extern sector_t swsusp_resume_block;
extern asmlinkage int swsusp_arch_suspend(void);
extern asmlinkage int swsusp_arch_resume(void);
extern int create_basic_memory_bitmaps(void);
extern void free_basic_memory_bitmaps(void);
extern int hibernate_preallocate_memory(void);
/**
* Auxiliary structure used for reading the snapshot image data and
* metadata from and writing them to the list of page backup entries
* (PBEs) which is the main data structure of swsusp.
*
* Using struct snapshot_handle we can transfer the image, including its
* metadata, as a continuous sequence of bytes with the help of
* snapshot_read_next() and snapshot_write_next().
*
* The code that writes the image to a storage or transfers it to
* the user land is required to use snapshot_read_next() for this
* purpose and it should not make any assumptions regarding the internal
* structure of the image. Similarly, the code that reads the image from
* a storage or transfers it from the user land is required to use
* snapshot_write_next().
*
* This may allow us to change the internal structure of the image
* in the future with considerably less effort.
*/
struct snapshot_handle {
unsigned int cur; /* number of the block of PAGE_SIZE bytes the
* next operation will refer to (ie. current)
*/
void *buffer; /* address of the block to read from
* or write to
*/
int sync_read; /* Set to one to notify the caller of
* snapshot_write_next() that it may
* need to call wait_on_bio_chain()
*/
};
/* This macro returns the address from/to which the caller of
* snapshot_read_next()/snapshot_write_next() is allowed to
* read/write data after the function returns
*/
#define data_of(handle) ((handle).buffer)
extern unsigned int snapshot_additional_pages(struct zone *zone);
extern unsigned long snapshot_get_image_size(void);
extern int snapshot_read_next(struct snapshot_handle *handle);
extern int snapshot_write_next(struct snapshot_handle *handle);
extern void snapshot_write_finalize(struct snapshot_handle *handle);
extern int snapshot_image_loaded(struct snapshot_handle *handle);
/* If unset, the snapshot device cannot be open. */
extern atomic_t snapshot_device_available;
extern sector_t alloc_swapdev_block(int swap);
extern void free_all_swap_pages(int swap);
extern int swsusp_swap_in_use(void);
/*
* Flags that can be passed from the hibernatig hernel to the "boot" kernel in
* the image header.
*/
#define SF_PLATFORM_MODE 1
#define SF_NOCOMPRESS_MODE 2
#define SF_CRC32_MODE 4
/* kernel/power/hibernate.c */
extern int swsusp_check(void);
extern void swsusp_free(void);
extern int swsusp_read(unsigned int *flags_p);
extern int swsusp_write(unsigned int flags);
extern void swsusp_close(fmode_t);
#ifdef CONFIG_SUSPEND
extern int swsusp_unmark(void);
#endif
struct timeval;
/* kernel/power/swsusp.c */
extern void swsusp_show_speed(ktime_t, ktime_t, unsigned int, char *);
#ifdef CONFIG_SUSPEND
/* kernel/power/suspend.c */
extern const char *pm_labels[];
extern const char *pm_states[];
extern int suspend_devices_and_enter(suspend_state_t state);
#else /* !CONFIG_SUSPEND */
static inline int suspend_devices_and_enter(suspend_state_t state)
{
return -ENOSYS;
}
#endif /* !CONFIG_SUSPEND */
#ifdef CONFIG_PM_TEST_SUSPEND
/* kernel/power/suspend_test.c */
extern void suspend_test_start(void);
extern void suspend_test_finish(const char *label);
#else /* !CONFIG_PM_TEST_SUSPEND */
static inline void suspend_test_start(void) {}
static inline void suspend_test_finish(const char *label) {}
#endif /* !CONFIG_PM_TEST_SUSPEND */
#ifdef CONFIG_PM_SLEEP
/* kernel/power/main.c */
extern int __pm_notifier_call_chain(unsigned long val, int nr_to_call,
int *nr_calls);
extern int pm_notifier_call_chain(unsigned long val);
#endif
#ifdef CONFIG_HIGHMEM
int restore_highmem(void);
#else
static inline unsigned int count_highmem_pages(void) { return 0; }
static inline int restore_highmem(void) { return 0; }
#endif
/*
* Suspend test levels
*/
enum {
/* keep first */
TEST_NONE,
TEST_CORE,
TEST_CPUS,
TEST_PLATFORM,
TEST_DEVICES,
TEST_FREEZER,
/* keep last */
__TEST_AFTER_LAST
};
#define TEST_FIRST TEST_NONE
#define TEST_MAX (__TEST_AFTER_LAST - 1)
extern int pm_test_level;
#ifdef CONFIG_SUSPEND_FREEZER
static inline int suspend_freeze_processes(void)
{
int error;
error = freeze_processes();
/*
* freeze_processes() automatically thaws every task if freezing
* fails. So we need not do anything extra upon error.
*/
if (error)
return error;
error = freeze_kernel_threads();
/*
* freeze_kernel_threads() thaws only kernel threads upon freezing
* failure. So we have to thaw the userspace tasks ourselves.
*/
if (error)
thaw_processes();
return error;
}
static inline void suspend_thaw_processes(void)
{
thaw_processes();
}
#else
static inline int suspend_freeze_processes(void)
{
return 0;
}
static inline void suspend_thaw_processes(void)
{
}
#endif
#ifdef CONFIG_PM_AUTOSLEEP
/* kernel/power/autosleep.c */
extern int pm_autosleep_init(void);
extern int pm_autosleep_lock(void);
extern void pm_autosleep_unlock(void);
extern suspend_state_t pm_autosleep_state(void);
extern int pm_autosleep_set_state(suspend_state_t state);
#else /* !CONFIG_PM_AUTOSLEEP */
static inline int pm_autosleep_init(void) { return 0; }
static inline int pm_autosleep_lock(void) { return 0; }
static inline void pm_autosleep_unlock(void) {}
static inline suspend_state_t pm_autosleep_state(void) { return PM_SUSPEND_ON; }
#endif /* !CONFIG_PM_AUTOSLEEP */
#ifdef CONFIG_PM_WAKELOCKS
/* kernel/power/wakelock.c */
extern ssize_t pm_show_wakelocks(char *buf, bool show_active);
extern int pm_wake_lock(const char *buf);
extern int pm_wake_unlock(const char *buf);
#endif /* !CONFIG_PM_WAKELOCKS */
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