tracing: WARN on rcuidle

ARCH_WANTS_NO_INSTR (a superset of CONFIG_GENERIC_ENTRY) disallows any
and all tracing when RCU isn't enabled.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.416110581@infradead.org

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 4b33b95eb8be70f0e55d9ba1bada8ae8aa1fd8bd..552f80b8362fb866b481aeabe83c7ac40f3a02ba 100644 (file)
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -177,6 +177,17 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
 #define __DO_TRACE_CALL(name, args)    __traceiter_##name(NULL, args)
 #endif /* CONFIG_HAVE_STATIC_CALL */
 
+/*
+ * ARCH_WANTS_NO_INSTR archs are expected to have sanitized entry and idle
+ * code that disallow any/all tracing/instrumentation when RCU isn't watching.
+ */
+#ifdef CONFIG_ARCH_WANTS_NO_INSTR
+#define RCUIDLE_COND(rcuidle)  (rcuidle)
+#else
+/* srcu can't be used from NMI */
+#define RCUIDLE_COND(rcuidle)  (rcuidle && in_nmi())
+#endif
+
 /*
  * it_func[0] is never NULL because there is at least one element in the array
  * when the array itself is non NULL.
@@ -188,8 +199,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
                if (!(cond))                                            \
                        return;                                         \
                                                                        \
-               /* srcu can't be used from NMI */                       \
-               WARN_ON_ONCE(rcuidle && in_nmi());                      \
+               if (WARN_ON_ONCE(RCUIDLE_COND(rcuidle)))                \
+                       return;                                         \
                                                                        \
                /* keep srcu and sched-rcu usage consistent */          \
                preempt_disable_notrace();                              \

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a555a861b97811b31f833d483cab0539f379258f..54ec1592ac794cfb7936497b3462ceaed42dceee 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3128,6 +3128,9 @@ void __trace_stack(struct trace_array *tr, unsigned int trace_ctx,
                return;
        }
 
+       if (WARN_ON_ONCE(IS_ENABLED(CONFIG_GENERIC_ENTRY)))
+               return;
+
        /*
         * When an NMI triggers, RCU is enabled via ct_nmi_enter(),
         * but if the above rcu_is_watching() failed, then the NMI