Commit 62822e2e authored Aug 11, 2016 by Thomas Garnier Committed by Rafael J. Wysocki Aug 12, 2016

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: bb3632c6 (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>

parent e4630fdd

kernel/power/hibernate.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -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;

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