x86/power: Make restore_processor_context() sane
authorAndy Lutomirski <luto@kernel.org>
Thu, 14 Dec 2017 21:19:07 +0000 (13:19 -0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 17 Apr 2019 06:36:38 +0000 (08:36 +0200)
commit39dbf53c9bb89bebae8aac458eaa806e578d267c
tree6794cadb1b7f5bd5aa6c8f9e5fac88580cf7775e
parentd72b48521648fc9ffc7c1299da519e905f83aab2
x86/power: Make restore_processor_context() sane

[ Upstream commit 7ee18d677989e99635027cee04c878950e0752b9 ]

My previous attempt to fix a couple of bugs in __restore_processor_context():

  5b06bbcfc2c6 ("x86/power: Fix some ordering bugs in __restore_processor_context()")

... introduced yet another bug, breaking suspend-resume.

Rather than trying to come up with a minimal fix, let's try to clean it up
for real.  This patch fixes quite a few things:

 - The old code saved a nonsensical subset of segment registers.
   The only registers that need to be saved are those that contain
   userspace state or those that can't be trivially restored without
   percpu access working.  (On x86_32, we can restore percpu access
   by writing __KERNEL_PERCPU to %fs.  On x86_64, it's easier to
   save and restore the kernel's GSBASE.)  With this patch, we
   restore hardcoded values to the kernel state where applicable and
   explicitly restore the user state after fixing all the descriptor
   tables.

 - We used to use an unholy mix of inline asm and C helpers for
   segment register access.  Let's get rid of the inline asm.

This fixes the reported s2ram hangs and make the code all around
more logical.

Analyzed-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reported-by: Pavel Machek <pavel@ucw.cz>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Tested-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bpetkov@suse.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Zhang Rui <rui.zhang@intel.com>
Fixes: 5b06bbcfc2c6 ("x86/power: Fix some ordering bugs in __restore_processor_context()")
Link: http://lkml.kernel.org/r/398ee68e5c0f766425a7b746becfc810840770ff.1513286253.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
arch/x86/include/asm/suspend_32.h
arch/x86/include/asm/suspend_64.h
arch/x86/power/cpu.c