libbpf-tools/klockstat: Support nested mutex_trylock

Since kernel 6.16, mutex_trylock() also have a nested version. Add the
support for it.

Moreover the nested version of mutex_lock_killable() is implemented
differently and mutex_lock_killable_nested symbol is replaced by
_mutex_lock_killable.

It fixes the following error of debug kernels:
libbpf: prog 'mutex_trylock_exit': failed to find kernel BTF type ID of 'mutex_trylock': -3
libbpf: prog 'mutex_trylock_exit': failed to prepare load attributes: -3
libbpf: prog 'mutex_trylock_exit': failed to load: -3
libbpf: failed to load object 'klockstat_bpf'
libbpf: failed to load BPF skeleton 'klockstat_bpf': -3
failed to load BPF object

Signed-off-by: Jerome Marchand <jmarchan@redhat.com>

Author: jeromemarchand

libbpf-tools/klockstat.c

@@ -103,7 +103,9 @@ static const char *lock_ksym_names[] = {
 	"mutex_lock_interruptible_nested",
 	"mutex_lock_killable",
 	"mutex_lock_killable_nested",
+	"_mutex_lock_killable",
 	"mutex_trylock",
+	"_mutex_trylock_nest_lock",
 	"down_read",
 	"down_read_nested",
 	"down_read_interruptible",
@@ -838,10 +840,24 @@ static void enable_fentry(struct klockstat_bpf *obj)
 				       "down_write_nested");
 	bpf_program__set_attach_target(obj->progs.down_write_exit, 0,
 				       "down_write_nested");
-	bpf_program__set_attach_target(obj->progs.down_write_killable, 0,
-				       "down_write_killable_nested");
-	bpf_program__set_attach_target(obj->progs.down_write_killable_exit, 0,
-				       "down_write_killable_nested");
+
+	/* Since v6.16 mutex_lock_killable nested variant is implemented differently */
+	if (fentry_can_attach("_mutex_lock_killable", NULL)) {
+		bpf_program__set_attach_target(obj->progs.mutex_lock_killable, 0,
+					       "_mutex_lock_killable");
+		bpf_program__set_attach_target(obj->progs.mutex_lock_killable_exit, 0,
+					       "_mutex_lock_killable");
+	} else {
+		bpf_program__set_attach_target(obj->progs.down_write_killable, 0,
+					       "down_write_killable_nested");
+		bpf_program__set_attach_target(obj->progs.down_write_killable_exit, 0,
+					       "down_write_killable_nested");
+	}
+
+	/* Since v6.16 mutex_trylock also have a nested variant */
+	if (fentry_can_attach("_mutex_trylock_nest_lock", NULL))
+		bpf_program__set_attach_target(obj->progs.mutex_trylock_exit, 0,
+					       "_mutex_trylock_nest_lock");
 }
 
 static void enable_kprobes(struct klockstat_bpf *obj)
@@ -906,10 +922,24 @@ static void enable_kprobes(struct klockstat_bpf *obj)
 				       "down_write_nested");
 	bpf_program__set_attach_target(obj->progs.kprobe_down_write_exit, 0,
 				       "down_write_nested");
-	bpf_program__set_attach_target(obj->progs.kprobe_down_write_killable, 0,
-				       "down_write_killable_nested");
-	bpf_program__set_attach_target(obj->progs.kprobe_down_write_killable_exit, 0,
-				       "down_write_killable_nested");
+
+	/* Since v6.16 mutex_lock_killable nested variant is implemented differently */
+	if (kprobe_exists("_mutex_lock_killable")) {
+		bpf_program__set_attach_target(obj->progs.mutex_lock_killable, 0,
+					       "_mutex_lock_killable");
+		bpf_program__set_attach_target(obj->progs.mutex_lock_killable_exit, 0,
+					       "_mutex_lock_killable");
+	} else {
+		bpf_program__set_attach_target(obj->progs.kprobe_down_write_killable, 0,
+					       "down_write_killable_nested");
+		bpf_program__set_attach_target(obj->progs.kprobe_down_write_killable_exit, 0,
+					       "down_write_killable_nested");
+	}
+
+	/* Since v6.16 mutex_trylock also have a nested variant */
+	if (kprobe_exists("_mutex_trylock_nest_lock"))
+		bpf_program__set_attach_target(obj->progs.mutex_trylock_exit, 0,
+					       "_mutex_trylock_nest_lock");
 }
 
 static void disable_nldump_ioctl_probes(struct klockstat_bpf *obj)