From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jessica Yu <jeyu@redhat.com>, Jiri Kosina <jikos@kernel.org>,
Miroslav Benes <mbenes@suse.cz>, Petr Mladek <pmladek@suse.com>
Cc: linux-kernel@vger.kernel.org, live-patching@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
x86@kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-s390@vger.kernel.org, Vojtech Pavlik <vojtech@suse.com>,
Jiri Slaby <jslaby@suse.cz>,
Chris J Arges <chris.j.arges@canonical.com>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Balbir Singh <bsingharora@gmail.com>
Subject: [PATCH v4 07/15] livepatch/s390: add TIF_PATCH_PENDING thread flag
Date: Thu, 19 Jan 2017 09:46:15 -0600 [thread overview]
Message-ID: <3817926949cd9f951d385d2d540b1e598ab0948e.1484839971.git.jpoimboe@redhat.com> (raw)
In-Reply-To: <cover.1484839971.git.jpoimboe@redhat.com>
From: Miroslav Benes <mbenes@suse.cz>
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 <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
---
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 97298c5..2084848 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:
--
2.7.4
next prev parent reply other threads:[~2017-01-19 15:48 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-19 15:46 [PATCH v4 00/15] livepatch: hybrid consistency model Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 01/15] stacktrace/x86: add function for detecting reliable stack traces Josh Poimboeuf
2017-01-26 13:56 ` Petr Mladek
2017-01-26 17:57 ` Josh Poimboeuf
2017-01-27 8:47 ` Miroslav Benes
2017-01-27 17:13 ` Josh Poimboeuf
2017-02-01 19:57 ` [PATCH v4.1 " Josh Poimboeuf
2017-02-02 14:39 ` Miroslav Benes
2017-01-19 15:46 ` [PATCH v4 02/15] x86/entry: define _TIF_ALLWORK_MASK flags explicitly Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 03/15] livepatch: create temporary klp_update_patch_state() stub Josh Poimboeuf
2017-01-27 8:52 ` Miroslav Benes
2017-01-19 15:46 ` [PATCH v4 04/15] livepatch/x86: add TIF_PATCH_PENDING thread flag Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 05/15] livepatch/powerpc: " Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 06/15] livepatch/s390: reorganize TIF thread flag bits Josh Poimboeuf
2017-01-19 15:46 ` Josh Poimboeuf [this message]
2017-01-19 15:46 ` [PATCH v4 08/15] livepatch: separate enabled and patched states Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 09/15] livepatch: remove unnecessary object loaded check Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 10/15] livepatch: move patching functions into patch.c Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 11/15] livepatch: use kstrtobool() in enabled_store() Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 12/15] livepatch: store function sizes Josh Poimboeuf
2017-01-19 15:46 ` [PATCH v4 13/15] livepatch: change to a per-task consistency model Josh Poimboeuf
2017-02-02 11:45 ` Petr Mladek
2017-02-02 11:47 ` Petr Mladek
2017-02-02 11:51 ` Petr Mladek
2017-02-03 16:21 ` Miroslav Benes
2017-02-03 20:39 ` Josh Poimboeuf
2017-02-06 16:44 ` Petr Mladek
2017-02-06 19:51 ` Josh Poimboeuf
2017-02-08 15:47 ` Petr Mladek
2017-02-08 16:46 ` Josh Poimboeuf
2017-02-09 10:24 ` Petr Mladek
2017-02-03 16:41 ` Miroslav Benes
2017-02-06 15:58 ` Josh Poimboeuf
2017-02-07 8:21 ` Miroslav Benes
2017-01-19 15:46 ` [PATCH v4 14/15] livepatch: add /proc/<pid>/patch_state Josh Poimboeuf
2017-01-31 14:31 ` Miroslav Benes
2017-01-31 14:56 ` Josh Poimboeuf
2017-02-01 8:54 ` Miroslav Benes
2017-01-19 15:46 ` [PATCH v4 15/15] livepatch: allow removal of a disabled patch Josh Poimboeuf
2017-02-03 16:48 ` Miroslav Benes
2017-02-01 20:02 ` [PATCH v4 00/15] livepatch: hybrid consistency model Josh Poimboeuf
2017-02-01 20:52 ` Miroslav Benes
2017-02-01 21:01 ` Jiri Kosina
2017-02-02 14:37 ` Petr Mladek
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