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

Masami Hiramatsu
2021-07-10T14:56:01Z

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

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.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))