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-rw-r--r--Documentation/ABI/testing/sysfs-kernel-livepatch12
-rw-r--r--Documentation/livepatch/livepatch.txt11
-rw-r--r--arch/powerpc/kernel/signal.c6
-rw-r--r--arch/x86/entry/common.c6
-rw-r--r--kernel/livepatch/core.c30
-rw-r--r--kernel/livepatch/transition.c41
-rw-r--r--kernel/livepatch/transition.h1
-rw-r--r--kernel/signal.c4
8 files changed, 102 insertions, 9 deletions
diff --git a/Documentation/ABI/testing/sysfs-kernel-livepatch b/Documentation/ABI/testing/sysfs-kernel-livepatch
index d5d39748382f..3bb9d5bc1ce3 100644
--- a/Documentation/ABI/testing/sysfs-kernel-livepatch
+++ b/Documentation/ABI/testing/sysfs-kernel-livepatch
@@ -33,6 +33,18 @@ Description:
An attribute which indicates whether the patch is currently in
transition.
+What: /sys/kernel/livepatch/<patch>/signal
+Date: Nov 2017
+KernelVersion: 4.15.0
+Contact: live-patching@vger.kernel.org
+Description:
+ A writable attribute that allows administrator to affect the
+ course of an existing transition. Writing 1 sends a fake
+ signal to all remaining blocking tasks. The fake signal
+ means that no proper signal is delivered (there is no data in
+ signal pending structures). Tasks are interrupted or woken up,
+ and forced to change their patched state.
+
What: /sys/kernel/livepatch/<patch>/<object>
Date: Nov 2014
KernelVersion: 3.19.0
diff --git a/Documentation/livepatch/livepatch.txt b/Documentation/livepatch/livepatch.txt
index ecdb18104ab0..9bcdef277a36 100644
--- a/Documentation/livepatch/livepatch.txt
+++ b/Documentation/livepatch/livepatch.txt
@@ -176,8 +176,12 @@ If a patch is in transition, this file shows 0 to indicate the task is
unpatched and 1 to indicate it's patched. Otherwise, if no patch is in
transition, it shows -1. Any tasks which are blocking the transition
can be signaled with SIGSTOP and SIGCONT to force them to change their
-patched state.
-
+patched state. This may be harmful to the system though.
+/sys/kernel/livepatch/<patch>/signal attribute provides a better alternative.
+Writing 1 to the attribute sends a fake signal to all remaining blocking
+tasks. No proper signal is actually delivered (there is no data in signal
+pending structures). Tasks are interrupted or woken up, and forced to change
+their patched state.
3.1 Adding consistency model support to new architectures
---------------------------------------------------------
@@ -435,6 +439,9 @@ Information about the registered patches can be found under
/sys/kernel/livepatch. The patches could be enabled and disabled
by writing there.
+/sys/kernel/livepatch/<patch>/signal attribute allows administrator to affect a
+patching operation.
+
See Documentation/ABI/testing/sysfs-kernel-livepatch for more details.
diff --git a/arch/powerpc/kernel/signal.c b/arch/powerpc/kernel/signal.c
index e9436c5e1e09..bf9c4e7792d1 100644
--- a/arch/powerpc/kernel/signal.c
+++ b/arch/powerpc/kernel/signal.c
@@ -153,6 +153,9 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
if (thread_info_flags & _TIF_UPROBE)
uprobe_notify_resume(regs);
+ if (thread_info_flags & _TIF_PATCH_PENDING)
+ klp_update_patch_state(current);
+
if (thread_info_flags & _TIF_SIGPENDING) {
BUG_ON(regs != current->thread.regs);
do_signal(current);
@@ -163,9 +166,6 @@ void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags)
tracehook_notify_resume(regs);
}
- if (thread_info_flags & _TIF_PATCH_PENDING)
- klp_update_patch_state(current);
-
user_enter();
}
diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index d7d3cc24baf4..1e3883e45687 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -153,6 +153,9 @@ static void exit_to_usermode_loop(struct pt_regs *regs, u32 cached_flags)
if (cached_flags & _TIF_UPROBE)
uprobe_notify_resume(regs);
+ if (cached_flags & _TIF_PATCH_PENDING)
+ klp_update_patch_state(current);
+
/* deal with pending signal delivery */
if (cached_flags & _TIF_SIGPENDING)
do_signal(regs);
@@ -165,9 +168,6 @@ 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_update_patch_state(current);
-
/* Disable IRQs and retry */
local_irq_disable();
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index de9e45dca70f..88766bd91803 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -454,6 +454,7 @@ EXPORT_SYMBOL_GPL(klp_enable_patch);
* /sys/kernel/livepatch/<patch>
* /sys/kernel/livepatch/<patch>/enabled
* /sys/kernel/livepatch/<patch>/transition
+ * /sys/kernel/livepatch/<patch>/signal
* /sys/kernel/livepatch/<patch>/<object>
* /sys/kernel/livepatch/<patch>/<object>/<function,sympos>
*/
@@ -528,11 +529,40 @@ static ssize_t transition_show(struct kobject *kobj,
patch == klp_transition_patch);
}
+static ssize_t signal_store(struct kobject *kobj, struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct klp_patch *patch;
+ int ret;
+ bool val;
+
+ patch = container_of(kobj, struct klp_patch, kobj);
+
+ /*
+ * klp_mutex lock is not grabbed here intentionally. It is not really
+ * needed. The race window is harmless and grabbing the lock would only
+ * hold the action back.
+ */
+ if (patch != klp_transition_patch)
+ return -EINVAL;
+
+ ret = kstrtobool(buf, &val);
+ if (ret)
+ return ret;
+
+ if (val)
+ klp_send_signals();
+
+ return count;
+}
+
static struct kobj_attribute enabled_kobj_attr = __ATTR_RW(enabled);
static struct kobj_attribute transition_kobj_attr = __ATTR_RO(transition);
+static struct kobj_attribute signal_kobj_attr = __ATTR_WO(signal);
static struct attribute *klp_patch_attrs[] = {
&enabled_kobj_attr.attr,
&transition_kobj_attr.attr,
+ &signal_kobj_attr.attr,
NULL
};
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 56add6327736..edcfcb8ebb2d 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -608,3 +608,44 @@ void klp_copy_process(struct task_struct *child)
/* TIF_PATCH_PENDING gets copied in setup_thread_stack() */
}
+
+/*
+ * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set.
+ * Kthreads with TIF_PATCH_PENDING set are woken up. Only admin can request this
+ * action currently.
+ */
+void klp_send_signals(void)
+{
+ struct task_struct *g, *task;
+
+ pr_notice("signaling remaining tasks\n");
+
+ read_lock(&tasklist_lock);
+ for_each_process_thread(g, task) {
+ if (!klp_patch_pending(task))
+ continue;
+
+ /*
+ * There is a small race here. We could see TIF_PATCH_PENDING
+ * set and decide to wake up a kthread or send a fake signal.
+ * Meanwhile the task could migrate itself and the action
+ * would be meaningless. It is not serious though.
+ */
+ if (task->flags & PF_KTHREAD) {
+ /*
+ * Wake up a kthread which sleeps interruptedly and
+ * still has not been migrated.
+ */
+ wake_up_state(task, TASK_INTERRUPTIBLE);
+ } else {
+ /*
+ * Send fake signal to all non-kthread tasks which are
+ * still not migrated.
+ */
+ spin_lock_irq(&task->sighand->siglock);
+ signal_wake_up(task, 0);
+ spin_unlock_irq(&task->sighand->siglock);
+ }
+ }
+ read_unlock(&tasklist_lock);
+}
diff --git a/kernel/livepatch/transition.h b/kernel/livepatch/transition.h
index 0f6e27c481f9..40522795a5f6 100644
--- a/kernel/livepatch/transition.h
+++ b/kernel/livepatch/transition.h
@@ -11,5 +11,6 @@ void klp_cancel_transition(void);
void klp_start_transition(void);
void klp_try_complete_transition(void);
void klp_reverse_transition(void);
+void klp_send_signals(void);
#endif /* _LIVEPATCH_TRANSITION_H */
diff --git a/kernel/signal.c b/kernel/signal.c
index 8dcd8825b2de..186143b06d00 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -40,6 +40,7 @@
#include <linux/cn_proc.h>
#include <linux/compiler.h>
#include <linux/posix-timers.h>
+#include <linux/livepatch.h>
#define CREATE_TRACE_POINTS
#include <trace/events/signal.h>
@@ -163,7 +164,8 @@ void recalc_sigpending_and_wake(struct task_struct *t)
void recalc_sigpending(void)
{
- if (!recalc_sigpending_tsk(current) && !freezing(current))
+ if (!recalc_sigpending_tsk(current) && !freezing(current) &&
+ !klp_patch_pending(current))
clear_thread_flag(TIF_SIGPENDING);
}