Commit 8c6eb7ca authored Jan 29, 2025 by Sebastian Andrzej Siewior Committed by Petr Pavlu Mar 10, 2025

bpf: Use RCU in all users of __module_text_address().



__module_address() can be invoked within a RCU section, there is no
requirement to have preemption disabled.

Replace the preempt_disable() section around __module_address() with
RCU.

Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Matt Bobrowski <mattbobrowski@google.com>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: bpf@vger.kernel.org
Cc: linux-trace-kernel@vger.kernel.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20250129084751.tH6iidUO@linutronix.de


Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>

parent 72ee1c20

kernel/trace/bpf_trace.c

+13 −11

Original line number	Diff line number	Diff line
		@@ -2345,10 +2345,9 @@ void bpf_put_raw_tracepoint(struct bpf_raw_event_map *btp)
		{
		struct module *mod;

		preempt_disable();
		guard(rcu)();
		mod = __module_address((unsigned long)btp);
		module_put(mod);
		preempt_enable();
		}

		static __always_inline
		@@ -2932,18 +2931,21 @@ static int get_modules_for_addrs(struct module **mods, unsigned long addrs, u3
		u32 i, err = 0;

		for (i = 0; i < addrs_cnt; i++) {
		bool skip_add = false;
		struct module *mod;

		preempt_disable();
		scoped_guard(rcu) {
		mod = __module_address(addrs[i]);
		/* Either no module or we it's already stored */
		/* Either no module or it's already stored */
		if (!mod \|\| has_module(&arr, mod)) {
		preempt_enable();
		continue;
		skip_add = true;
		break; /* scoped_guard */
		}
		if (!try_module_get(mod))
		err = -EINVAL;
		preempt_enable();
		}
		if (skip_add)
		continue;
		if (err)
		break;
		err = add_module(&arr, mod);