From patchwork Thu Dec 8 18:08:32 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Josh Poimboeuf X-Patchwork-Id: 704179 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [103.22.144.68]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3tZNyY5Xsnz9t1H for ; Fri, 9 Dec 2016 05:23:01 +1100 (AEDT) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3tZNyY4Fb7zDwM9 for ; Fri, 9 Dec 2016 05:23:01 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3tZNkc0RdYzDw6d for ; Fri, 9 Dec 2016 05:12:40 +1100 (AEDT) Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 45AB685545; Thu, 8 Dec 2016 18:12:38 +0000 (UTC) Received: from treble.redhat.com (ovpn-116-9.phx2.redhat.com [10.3.116.9]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id uB8ICOL4013607; Thu, 8 Dec 2016 13:12:36 -0500 From: Josh Poimboeuf To: Jessica Yu , Jiri Kosina , Miroslav Benes , Petr Mladek Subject: [PATCH v3 07/15] livepatch/s390: add TIF_PATCH_PENDING thread flag Date: Thu, 8 Dec 2016 12:08:32 -0600 Message-Id: <4409facb9f7ca7d33e9de114c9a458eb41556393.1481220077.git.jpoimboe@redhat.com> In-Reply-To: References: X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 08 Dec 2016 18:12:38 +0000 (UTC) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, Vojtech Pavlik , Peter Zijlstra , x86@kernel.org, Heiko Carstens , linux-kernel@vger.kernel.org, Andy Lutomirski , live-patching@vger.kernel.org, Jiri Slaby , linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Chris J Arges Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Miroslav Benes Update a task's patch state when returning from a system call or user space interrupt, or after handling a signal. This greatly increases the chances of a patch operation succeeding. If a task is I/O bound, it can be patched when returning from a system call. If a task is CPU bound, it can be patched when returning from an interrupt. If a task is sleeping on a to-be-patched function, the user can send SIGSTOP and SIGCONT to force it to switch. Since there are two ways the syscall can be restarted on return from a signal handling process, it is important to clear the flag before do_signal() is called. Otherwise we could miss the migration if we used SIGSTOP/SIGCONT procedure or fake signal to migrate patching blocking tasks. If we place our hook to sysc_work label in entry before TIF_SIGPENDING is evaluated we kill two birds with one stone. The task is correctly migrated in all return paths from a syscall. Signed-off-by: Miroslav Benes Signed-off-by: Josh Poimboeuf --- arch/s390/include/asm/thread_info.h | 2 ++ arch/s390/kernel/entry.S | 31 ++++++++++++++++++++++++++++++- 2 files changed, 32 insertions(+), 1 deletion(-) diff --git a/arch/s390/include/asm/thread_info.h b/arch/s390/include/asm/thread_info.h index 4977668..646845e 100644 --- a/arch/s390/include/asm/thread_info.h +++ b/arch/s390/include/asm/thread_info.h @@ -56,6 +56,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define TIF_SIGPENDING 1 /* signal pending */ #define TIF_NEED_RESCHED 2 /* rescheduling necessary */ #define TIF_UPROBE 3 /* breakpointed or single-stepping */ +#define TIF_PATCH_PENDING 4 /* pending live patching update */ #define TIF_31BIT 16 /* 32bit process */ #define TIF_MEMDIE 17 /* is terminating due to OOM killer */ @@ -74,6 +75,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src); #define _TIF_SIGPENDING _BITUL(TIF_SIGPENDING) #define _TIF_NEED_RESCHED _BITUL(TIF_NEED_RESCHED) #define _TIF_UPROBE _BITUL(TIF_UPROBE) +#define _TIF_PATCH_PENDING _BITUL(TIF_PATCH_PENDING) #define _TIF_31BIT _BITUL(TIF_31BIT) #define _TIF_SINGLE_STEP _BITUL(TIF_SINGLE_STEP) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 161f4e6..33848a8 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -47,7 +47,7 @@ STACK_SIZE = 1 << STACK_SHIFT STACK_INIT = STACK_SIZE - STACK_FRAME_OVERHEAD - __PT_SIZE _TIF_WORK = (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_NEED_RESCHED | \ - _TIF_UPROBE) + _TIF_UPROBE | _TIF_PATCH_PENDING) _TIF_TRACE = (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \ _TIF_SYSCALL_TRACEPOINT) _CIF_WORK = (_CIF_MCCK_PENDING | _CIF_ASCE | _CIF_FPU) @@ -352,6 +352,11 @@ ENTRY(system_call) #endif TSTMSK __PT_FLAGS(%r11),_PIF_PER_TRAP jo .Lsysc_singlestep +#ifdef CONFIG_LIVEPATCH + TSTMSK __TI_flags(%r12),_TIF_PATCH_PENDING + jo .Lsysc_patch_pending # handle live patching just before + # signals and possible syscall restart +#endif TSTMSK __TI_flags(%r12),_TIF_SIGPENDING jo .Lsysc_sigpending TSTMSK __TI_flags(%r12),_TIF_NOTIFY_RESUME @@ -426,6 +431,16 @@ ENTRY(system_call) #endif # +# _TIF_PATCH_PENDING is set, call klp_update_patch_state +# +#ifdef CONFIG_LIVEPATCH +.Lsysc_patch_pending: + lg %r2,__LC_CURRENT # pass pointer to task struct + larl %r14,.Lsysc_return + jg klp_update_patch_state +#endif + +# # _PIF_PER_TRAP is set, call do_per_trap # .Lsysc_singlestep: @@ -674,6 +689,10 @@ ENTRY(io_int_handler) jo .Lio_mcck_pending TSTMSK __TI_flags(%r12),_TIF_NEED_RESCHED jo .Lio_reschedule +#ifdef CONFIG_LIVEPATCH + TSTMSK __TI_flags(%r12),_TIF_PATCH_PENDING + jo .Lio_patch_pending +#endif TSTMSK __TI_flags(%r12),_TIF_SIGPENDING jo .Lio_sigpending TSTMSK __TI_flags(%r12),_TIF_NOTIFY_RESUME @@ -720,6 +739,16 @@ ENTRY(io_int_handler) j .Lio_return # +# _TIF_PATCH_PENDING is set, call klp_update_patch_state +# +#ifdef CONFIG_LIVEPATCH +.Lio_patch_pending: + lg %r2,__LC_CURRENT # pass pointer to task struct + larl %r14,.Lio_return + jg klp_update_patch_state +#endif + +# # _TIF_SIGPENDING or is set, call do_signal # .Lio_sigpending: