Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932279AbcLGHQ0 (ORCPT ); Wed, 7 Dec 2016 02:16:26 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:58042 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752708AbcLGHIH (ORCPT ); Wed, 7 Dec 2016 02:08:07 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, James Morse , Lorenzo Pieralisi , Will Deacon Subject: [PATCH 4.4 13/13] arm64: suspend: Reconfigure PSTATE after resume from idle Date: Wed, 7 Dec 2016 08:07:52 +0100 Message-Id: <20161207070717.199713933@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161207070716.317145973@linuxfoundation.org> References: <20161207070716.317145973@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1979 Lines: 58 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: James Morse commit d08544127d9fb4505635e3cb6871fd50a42947bd upstream. The suspend/resume path in kernel/sleep.S, as used by cpu-idle, does not save/restore PSTATE. As a result of this cpufeatures that were detected and have bits in PSTATE get lost when we resume from idle. UAO gets set appropriately on the next context switch. PAN will be re-enabled next time we return from user-space, but on a preemptible kernel we may run work accessing user space before this point. Add code to re-enable theses two features in __cpu_suspend_exit(). We re-use uao_thread_switch() passing current. Signed-off-by: James Morse Cc: Lorenzo Pieralisi Signed-off-by: Will Deacon [Removed UAO hooks and commit-message references: this feature is not present in v4.4] Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/suspend.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/arch/arm64/kernel/suspend.c +++ b/arch/arm64/kernel/suspend.c @@ -1,7 +1,9 @@ #include #include #include +#include #include +#include #include #include #include @@ -111,6 +113,13 @@ int cpu_suspend(unsigned long arg, int ( set_my_cpu_offset(per_cpu_offset(smp_processor_id())); /* + * PSTATE was not saved over suspend/resume, re-enable any + * detected features that might not have been set correctly. + */ + asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, + CONFIG_ARM64_PAN)); + + /* * Restore HW breakpoint registers to sane values * before debug exceptions are possibly reenabled * through local_dbg_restore.