Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753757AbcD1Us0 (ORCPT ); Thu, 28 Apr 2016 16:48:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57595 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753550AbcD1UpY (ORCPT ); Thu, 28 Apr 2016 16:45:24 -0400 From: Josh Poimboeuf To: Jessica Yu , Jiri Kosina , Miroslav Benes , Ingo Molnar , Peter Zijlstra , Michael Ellerman , Heiko Carstens Cc: live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Vojtech Pavlik , Jiri Slaby , Petr Mladek , Chris J Arges , Andy Lutomirski Subject: [RFC PATCH v2 09/18] livepatch/x86: add TIF_PATCH_PENDING thread flag Date: Thu, 28 Apr 2016 15:44:40 -0500 Message-Id: <6360fe5cab85aad424600518f645a9ac773cc72e.1461875890.git.jpoimboe@redhat.com> In-Reply-To: References: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Thu, 28 Apr 2016 20:45:24 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3183 Lines: 77 Add the TIF_PATCH_PENDING thread flag to enable the new livepatch per-task consistency model for x86_64. The bit getting set indicates the thread has a pending patch which needs to be applied when the thread exits the kernel. The bit is placed in the least-significant word of the thread_info flags so that it gets automatically included in the _TIF_ALLWORK_MASK macro. This results in exit_to_usermode_loop() and klp_patch_task() getting called when the bit is set. Signed-off-by: Josh Poimboeuf --- arch/x86/entry/common.c | 9 ++++++--- arch/x86/include/asm/thread_info.h | 2 ++ 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c index ec138e5..0eaa1d9 100644 --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -202,14 +203,13 @@ long syscall_trace_enter(struct pt_regs *regs) #define EXIT_TO_USERMODE_LOOP_FLAGS \ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ - _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY) + _TIF_NEED_RESCHED | _TIF_USER_RETURN_NOTIFY | _TIF_PATCH_PENDING) static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags) { /* * In order to return to user mode, we need to have IRQs off with - * none of _TIF_SIGPENDING, _TIF_NOTIFY_RESUME, _TIF_USER_RETURN_NOTIFY, - * _TIF_UPROBE, or _TIF_NEED_RESCHED set. Several of these flags + * none of EXIT_TO_USERMODE_LOOP_FLAGS set. Several of these flags * can be set at any time on preemptable kernels if we have IRQs on, * so we need to loop. Disabling preemption wouldn't help: doing the * work to clear some of the flags can sleep. @@ -236,6 +236,9 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags) if (cached_flags & _TIF_USER_RETURN_NOTIFY) fire_user_return_notifiers(); + if (cached_flags & _TIF_PATCH_PENDING) + klp_patch_task(current); + /* Disable IRQs and retry */ local_irq_disable(); diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index 30c133a..4e4f50e 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -97,6 +97,7 @@ struct thread_info { #define TIF_SECCOMP 8 /* secure computing */ #define TIF_USER_RETURN_NOTIFY 11 /* notify kernel of userspace return */ #define TIF_UPROBE 12 /* breakpointed or singlestepping */ +#define TIF_PATCH_PENDING 13 /* pending live patching update */ #define TIF_NOTSC 16 /* TSC is not accessible in userland */ #define TIF_IA32 17 /* IA32 compatibility process */ #define TIF_FORK 18 /* ret_from_fork */ @@ -121,6 +122,7 @@ struct thread_info { #define _TIF_SECCOMP (1 << TIF_SECCOMP) #define _TIF_USER_RETURN_NOTIFY (1 << TIF_USER_RETURN_NOTIFY) #define _TIF_UPROBE (1 << TIF_UPROBE) +#define _TIF_PATCH_PENDING (1 << TIF_PATCH_PENDING) #define _TIF_NOTSC (1 << TIF_NOTSC) #define _TIF_IA32 (1 << TIF_IA32) #define _TIF_FORK (1 << TIF_FORK) -- 2.4.11