Re: [PATCH v5 1/2] kprobes: textmem API

[Google]

On Tue, 26 Mar 2024 00:09:42 +0200
"Jarkko Sakkinen" <jarkko@xxxxxxxxxx> wrote:

> On Mon Mar 25, 2024 at 11:55 PM EET, Jarkko Sakkinen wrote:
> > +#ifdef CONFIG_MODULES
> >  	if (register_module_notifier(&trace_kprobe_module_nb))
> >  		return -EINVAL;
> > +#endif /* CONFIG_MODULES */
> 
> register_module_notifier() does have "dummy" version but what
> would I pass to it. It makes more mess than it cleans to declare
> also a "dummy" version of trace_kprobe_module_nb.

That is better than having #ifdef in the function.

> 
> The callback itself has too tight module subsystem bindings so
> that they could be simply flagged with IS_DEFINED() (or correct
> if I'm mistaken, this the conclusion I've ended up with).

Please try this.

-----
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 70dc6179086e..bc98db14927f 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2625,6 +2625,7 @@ static void remove_module_kprobe_blacklist(struct module *mod)
 	}
 }
 
+#ifdef CONFIG_MODULES
 /* Module notifier call back, checking kprobes on the module */
 static int kprobes_module_callback(struct notifier_block *nb,
 				   unsigned long val, void *data)
@@ -2675,6 +2676,9 @@ static int kprobes_module_callback(struct notifier_block *nb,
 	mutex_unlock(&kprobe_mutex);
 	return NOTIFY_DONE;
 }
+#else
+#define kprobes_module_callback	(NULL)
+#endif
 
 static struct notifier_block kprobe_module_nb = {
 	.notifier_call = kprobes_module_callback,
@@ -2739,7 +2743,7 @@ static int __init init_kprobes(void)
 	err = arch_init_kprobes();
 	if (!err)
 		err = register_die_notifier(&kprobe_exceptions_nb);
-	if (!err)
+	if (!err && IS_ENABLED(CONFIG_MODULES))
 		err = register_module_notifier(&kprobe_module_nb);
 
 	kprobes_initialized = (err == 0);

-----

Thank you,

-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>