kallsyms: explain why the _Static_assert is needed

Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/lkml/202208171330.BB5B081D1@keescook/
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: ojeda

scripts/kallsyms.c

@@ -32,7 +32,13 @@
 
 #define KSYM_NAME_LEN		512
 
-/* A substantially bigger size than the current maximum. */
+/*
+ * A substantially bigger size than the current maximum.
+ *
+ * It cannot be defined as an expression because it gets stringified
+ * for the fscanf() format string. Therefore, a _Static_assert() is
+ * used instead to maintain the relationship with KSYM_NAME_LEN.
+ */
 #define KSYM_NAME_LEN_BUFFER	2048
 _Static_assert(
 	KSYM_NAME_LEN_BUFFER == KSYM_NAME_LEN * 4,