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: bb3632c (PM / sleep: trace events for suspend/resume)
Reported-and-tested-by: Borislav Petkov <[email protected]>
Reported-by: Jiri Kosina <[email protected]>
Tested-by: Rafael J. Wysocki <[email protected]>
Tested-by: Jiri Kosina <[email protected]>
Signed-off-by: Thomas Garnier <[email protected]>
Acked-by: Pavel Machek <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

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;