From e3681107bc9f97c5948a1c8a3a97ac64907210ce Mon Sep 17 00:00:00 2001 From: Nathan Lynch Date: Tue, 12 Dec 2023 11:01:55 -0600 Subject: [PATCH] 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: "Aneesh Kumar K.V (IBM)" Signed-off-by: Nathan Lynch Signed-off-by: Michael Ellerman Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-8-e9eafd0c8c6c@linux.ibm.com --- arch/powerpc/kernel/rtas.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 72f6b5a402dde..7e793b503e29f 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -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)