kcsan: Print if strict or non-strict during init

Show a brief message if KCSAN is strict or non-strict, and if non-strict
also say that CONFIG_KCSAN_STRICT=y can be used to see all data races.

This is to hint to users of KCSAN who blindly use the default config
that their configuration might miss data races of interest.

Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c
index 439edb9dcbb13ae24abb4eaad1b12505d793a854..76e67d1e02d48bb0fc267e66d0e92603124229bf 100644 (file)
--- a/kernel/kcsan/core.c
+++ b/kernel/kcsan/core.c
@@ -656,6 +656,15 @@ void __init kcsan_init(void)
                pr_info("enabled early\n");
                WRITE_ONCE(kcsan_enabled, true);
        }
+
+       if (IS_ENABLED(CONFIG_KCSAN_REPORT_VALUE_CHANGE_ONLY) ||
+           IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC) ||
+           IS_ENABLED(CONFIG_KCSAN_PERMISSIVE) ||
+           IS_ENABLED(CONFIG_KCSAN_IGNORE_ATOMICS)) {
+               pr_warn("non-strict mode configured - use CONFIG_KCSAN_STRICT=y to see all data races\n");
+       } else {
+               pr_info("strict mode configured\n");
+       }
 }
 
 /* === Exported interface =================================================== */