| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 68/73] PM / hibernate: Restore processor state before using per-CPU variables | Date | Wed, 28 Sep 2016 11:05:38 +0200 |
| |
4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Thomas Garnier <thgarnie@google.com>
commit 62822e2ec4ad091ba31f823f577ef80db52e3c2c upstream.
Restore the processor state before calling any other functions to ensure per-CPU variables can be used with KASLR memory randomization.
Tracing functions use per-CPU variables (GS based on x86) and one was called just before restoring the processor state fully. It resulted in a double fault when both the tracing & the exception handler functions tried to use a per-CPU variable.
Fixes: bb3632c6101b (PM / sleep: trace events for suspend/resume) Reported-and-tested-by: Borislav Petkov <bp@suse.de> Reported-by: Jiri Kosina <jikos@kernel.org> Tested-by: Rafael J. Wysocki <rafael@kernel.org> Tested-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Thomas Garnier <thgarnie@google.com> Acked-by: Pavel Machek <pavel@ucw.cz> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- kernel/power/hibernate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -299,12 +299,12 @@ static int create_image(int platform_mod save_processor_state(); trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, true); error = swsusp_arch_suspend(); + /* Restore control flow magically appears here */ + restore_processor_state(); trace_suspend_resume(TPS("machine_suspend"), PM_EVENT_HIBERNATE, false); if (error) printk(KERN_ERR "PM: Error %d creating hibernation image\n", error); - /* Restore control flow magically appears here */ - restore_processor_state(); if (!in_suspend) events_check_enabled = false;
|