linux-kernel - [PATCH] livepatch: Add KLP

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Message-Id: <20240402030827.97207-1-zhangwarden@gmail.com>
Date: Tue,  2 Apr 2024 11:08:27 +0800
From: zhangwarden@...il.com
To: jpoimboe@...nel.org,
	mbenes@...e.cz,
	jikos@...nel.org,
	pmladek@...e.com,
	joe.lawrence@...hat.com
Cc: live-patching@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Wardenjohn <zhangwarden@...il.com>
Subject: [PATCH] livepatch: Add KLP_IDLE state

From: Wardenjohn <zhangwarden@...il.com>

---
 include/linux/livepatch.h     |  1 +
 kernel/livepatch/patch.c      |  2 +-
 kernel/livepatch/transition.c | 24 ++++++++++++------------
 3 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
index 9b9b38e89563..c1c53cd5b227 100644
--- a/include/linux/livepatch.h
+++ b/include/linux/livepatch.h
@@ -19,6 +19,7 @@
 
 /* task patch states */
 #define KLP_UNDEFINED	-1
+#define KLP_IDLE       -1
 #define KLP_UNPATCHED	 0
 #define KLP_PATCHED	 1
 
diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 4152c71507e2..01d3219289ee 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -95,7 +95,7 @@ static void notrace klp_ftrace_handler(unsigned long ip,
 
 		patch_state = current->patch_state;
 
-		WARN_ON_ONCE(patch_state == KLP_UNDEFINED);
+		WARN_ON_ONCE(patch_state == KLP_IDLE);
 
 		if (patch_state == KLP_UNPATCHED) {
 			/*
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index e54c3d60a904..73f8f98dba84 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -23,7 +23,7 @@ static DEFINE_PER_CPU(unsigned long[MAX_STACK_ENTRIES], klp_stack_entries);
 
 struct klp_patch *klp_transition_patch;
 
-static int klp_target_state = KLP_UNDEFINED;
+static int klp_target_state = KLP_IDLE;
 
 static unsigned int klp_signals_cnt;
 
@@ -123,21 +123,21 @@ static void klp_complete_transition(void)
 		klp_for_each_func(obj, func)
 			func->transition = false;
 
-	/* Prevent klp_ftrace_handler() from seeing KLP_UNDEFINED state */
+	/* Prevent klp_ftrace_handler() from seeing KLP_IDLE state */
 	if (klp_target_state == KLP_PATCHED)
 		klp_synchronize_transition();
 
 	read_lock(&tasklist_lock);
 	for_each_process_thread(g, task) {
 		WARN_ON_ONCE(test_tsk_thread_flag(task, TIF_PATCH_PENDING));
-		task->patch_state = KLP_UNDEFINED;
+		task->patch_state = KLP_IDLE;
 	}
 	read_unlock(&tasklist_lock);
 
 	for_each_possible_cpu(cpu) {
 		task = idle_task(cpu);
 		WARN_ON_ONCE(test_tsk_thread_flag(task, TIF_PATCH_PENDING));
-		task->patch_state = KLP_UNDEFINED;
+		task->patch_state = KLP_IDLE;
 	}
 
 	klp_for_each_object(klp_transition_patch, obj) {
@@ -152,7 +152,7 @@ static void klp_complete_transition(void)
 	pr_notice("'%s': %s complete\n", klp_transition_patch->mod->name,
 		  klp_target_state == KLP_PATCHED ? "patching" : "unpatching");
 
-	klp_target_state = KLP_UNDEFINED;
+	klp_target_state = KLP_IDLE;
 	klp_transition_patch = NULL;
 }
 
@@ -455,7 +455,7 @@ void klp_try_complete_transition(void)
 	struct klp_patch *patch;
 	bool complete = true;
 
-	WARN_ON_ONCE(klp_target_state == KLP_UNDEFINED);
+	WARN_ON_ONCE(klp_target_state == KLP_IDLE);
 
 	/*
 	 * Try to switch the tasks to the target patch state by walking their
@@ -532,7 +532,7 @@ void klp_start_transition(void)
 	struct task_struct *g, *task;
 	unsigned int cpu;
 
-	WARN_ON_ONCE(klp_target_state == KLP_UNDEFINED);
+	WARN_ON_ONCE(klp_target_state == KLP_IDLE);
 
 	pr_notice("'%s': starting %s transition\n",
 		  klp_transition_patch->mod->name,
@@ -578,7 +578,7 @@ void klp_init_transition(struct klp_patch *patch, int state)
 	struct klp_func *func;
 	int initial_state = !state;
 
-	WARN_ON_ONCE(klp_target_state != KLP_UNDEFINED);
+	WARN_ON_ONCE(klp_target_state != KLP_IDLE);
 
 	klp_transition_patch = patch;
 
@@ -597,7 +597,7 @@ void klp_init_transition(struct klp_patch *patch, int state)
 	 */
 	read_lock(&tasklist_lock);
 	for_each_process_thread(g, task) {
-		WARN_ON_ONCE(task->patch_state != KLP_UNDEFINED);
+		WARN_ON_ONCE(task->patch_state != KLP_IDLE);
 		task->patch_state = initial_state;
 	}
 	read_unlock(&tasklist_lock);
@@ -607,19 +607,19 @@ void klp_init_transition(struct klp_patch *patch, int state)
 	 */
 	for_each_possible_cpu(cpu) {
 		task = idle_task(cpu);
-		WARN_ON_ONCE(task->patch_state != KLP_UNDEFINED);
+		WARN_ON_ONCE(task->patch_state != KLP_DILE);
 		task->patch_state = initial_state;
 	}
 
 	/*
 	 * Enforce the order of the task->patch_state initializations and the
 	 * func->transition updates to ensure that klp_ftrace_handler() doesn't
-	 * see a func in transition with a task->patch_state of KLP_UNDEFINED.
+	 * see a func in transition with a task->patch_state of KLP_IDLE.
 	 *
 	 * Also enforce the order of the klp_target_state write and future
 	 * TIF_PATCH_PENDING writes to ensure klp_update_patch_state() and
 	 * __klp_sched_try_switch() don't set a task->patch_state to
-	 * KLP_UNDEFINED.
+	 * KLP_IDLE.
 	 */
 	smp_wmb();
 
-- 
2.37.3