Commit e3681107 authored by Nathan Lynch's avatar Nathan Lynch Committed by Michael Ellerman
Browse files

powerpc/rtas: Warn if per-function lock isn't held 



If the function descriptor has a populated lock member, then callers
are required to hold it across calls. Now that the firmware activation
sequence is appropriately guarded, we can warn when the requirement
isn't satisfied.

__do_enter_rtas_trace() gets reorganized a bit as a result of
performing the function descriptor lookup unconditionally now.

Reviewed-by: default avatar"Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: default avatarNathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-8-e9eafd0c8c6c@linux.ibm.com
parent dc7637c4

arch/powerpc/kernel/rtas.c

+9 −12
Original line number Diff line number Diff line
@@ -671,28 +671,25 @@ static void __do_enter_rtas(struct rtas_args *args) 


static void __do_enter_rtas_trace(struct rtas_args *args)

{

	const char *name = NULL;

	const struct rtas_function *func = rtas_token_to_function(be32_to_cpu(args->token));



	if (args == &rtas_args)

		lockdep_assert_held(&rtas_lock);

	/*

	 * If the tracepoints that consume the function name aren't

	 * active, avoid the lookup.

	 * If there is a per-function lock, it must be held by the

	 * caller.

	 */

	if ((trace_rtas_input_enabled() || trace_rtas_output_enabled())) {

		const s32 token = be32_to_cpu(args->token);

		const struct rtas_function *func = rtas_token_to_function(token);

	if (func->lock)

		lockdep_assert_held(func->lock);



		name = func->name;

	}

	if (args == &rtas_args)

		lockdep_assert_held(&rtas_lock);



	trace_rtas_input(args, name);

	trace_rtas_input(args, func->name);

	trace_rtas_ll_entry(args);



	__do_enter_rtas(args);



	trace_rtas_ll_exit(args);

	trace_rtas_output(args, name);

	trace_rtas_output(args, func->name);

}



static void do_enter_rtas(struct rtas_args *args)