linux-kernel - [PATCH -tip v2 4/6] kprobes: Add assertions for required lock

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Date:   Sun, 11 Jul 2021 16:34:51 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     X86 ML <x86@...nel.org>, Ingo Molnar <mingo@...nel.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Daniel Xu <dxu@...uu.xyz>, linux-kernel@...r.kernel.org,
        bpf@...r.kernel.org, kuba@...nel.org, mingo@...hat.com,
        ast@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>, kernel-team@...com,
        yhs@...com, linux-ia64@...r.kernel.org,
        Abhishek Sagar <sagar.abhishek@...il.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Joe Perches <joe@...ches.com>
Subject: [PATCH -tip v2 4/6] kprobes: Add assertions for required lock

Add assertions for required locks instead of comment it
so that the lockdep can inspect locks automatically.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 kernel/kprobes.c |   19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index e5e1400072c8..a99fd840b5c9 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -959,11 +959,13 @@ int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
 }
 #endif /* CONFIG_SYSCTL */
 
-/* Put a breakpoint for a probe. Must be called with 'text_mutex' locked. */
+/* Put a breakpoint for a probe. */
 static void __arm_kprobe(struct kprobe *p)
 {
 	struct kprobe *_p;
 
+	lockdep_assert_held(&text_mutex);
+
 	/* Find the overlapping optimized kprobes. */
 	_p = get_optimized_kprobe((unsigned long)p->addr);
 	if (unlikely(_p))
@@ -974,11 +976,13 @@ static void __arm_kprobe(struct kprobe *p)
 	optimize_kprobe(p);	/* Try to optimize (add kprobe to a list) */
 }
 
-/* Remove the breakpoint of a probe. Must be called with 'text_mutex' locked. */
+/* Remove the breakpoint of a probe. */
 static void __disarm_kprobe(struct kprobe *p, bool reopt)
 {
 	struct kprobe *_p;
 
+	lockdep_assert_held(&text_mutex);
+
 	/* Try to unoptimize */
 	unoptimize_kprobe(p, kprobes_all_disarmed);
 
@@ -1056,12 +1060,13 @@ static int prepare_kprobe(struct kprobe *p)
 	return arch_prepare_kprobe_ftrace(p);
 }
 
-/* Caller must lock 'kprobe_mutex' */
 static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 			       int *cnt)
 {
 	int ret = 0;
 
+	lockdep_assert_held(&kprobe_mutex);
+
 	ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
 	if (WARN_ONCE(ret < 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p->addr, ret))
 		return ret;
@@ -1093,12 +1098,13 @@ static int arm_kprobe_ftrace(struct kprobe *p)
 		ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
 }
 
-/* Caller must lock 'kprobe_mutex'. */
 static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
 				  int *cnt)
 {
 	int ret = 0;
 
+	lockdep_assert_held(&kprobe_mutex);
+
 	if (*cnt == 1) {
 		ret = unregister_ftrace_function(ops);
 		if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret))
@@ -1138,7 +1144,6 @@ static inline int disarm_kprobe_ftrace(struct kprobe *p)
 }
 #endif
 
-/* Arm a kprobe with 'text_mutex'. */
 static int arm_kprobe(struct kprobe *kp)
 {
 	if (unlikely(kprobe_ftrace(kp)))
@@ -1153,7 +1158,6 @@ static int arm_kprobe(struct kprobe *kp)
 	return 0;
 }
 
-/* Disarm a kprobe with 'text_mutex'. */
 static int disarm_kprobe(struct kprobe *kp, bool reopt)
 {
 	if (unlikely(kprobe_ftrace(kp)))
@@ -1696,12 +1700,13 @@ static int aggr_kprobe_disabled(struct kprobe *ap)
 	return 1;
 }
 
-/* Disable one kprobe: Make sure called under 'kprobe_mutex' is locked. */
 static struct kprobe *__disable_kprobe(struct kprobe *p)
 {
 	struct kprobe *orig_p;
 	int ret;
 
+	lockdep_assert_held(&kprobe_mutex);
+
 	/* Get an original kprobe for return */
 	orig_p = __get_valid_kprobe(p);
 	if (unlikely(orig_p == NULL))