PM / hibernate: Restore processor state before using per-CPU variables

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>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 0ee1df0a0bd6..61761aa7cc19 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -300,12 +300,12 @@ static int create_image(int platform_mode)
         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;