static_call: Pull some static_call declarations to the type headers

[ Upstream commit 880cfed3a012d7863f42251791cea7fe78c39390 ]

Some static call declarations are going to be needed on low level header
files. Move the necessary material to the dedicated static call types
header to avoid inclusion dependency hell.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lkml.kernel.org/r/20210118141223.123667-4-frederic@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

tools/include/linux/static_call_types.h

@@ -4,6 +4,7 @@
 
 #include <linux/types.h>
 #include <linux/stringify.h>
+#include <linux/compiler.h>
 
 #define STATIC_CALL_KEY_PREFIX		__SCK__
 #define STATIC_CALL_KEY_PREFIX_STR	__stringify(STATIC_CALL_KEY_PREFIX)
@@ -32,4 +33,30 @@ struct static_call_site {
 	s32 key;
 };
 
+#define DECLARE_STATIC_CALL(name, func)					\
+	extern struct static_call_key STATIC_CALL_KEY(name);		\
+	extern typeof(func) STATIC_CALL_TRAMP(name);
+
+#ifdef CONFIG_HAVE_STATIC_CALL
+
+/*
+ * __ADDRESSABLE() is used to ensure the key symbol doesn't get stripped from
+ * the symbol table so that objtool can reference it when it generates the
+ * .static_call_sites section.
+ */
+#define __static_call(name)						\
+({									\
+	__ADDRESSABLE(STATIC_CALL_KEY(name));				\
+	&STATIC_CALL_TRAMP(name);					\
+})
+
+#define static_call(name)	__static_call(name)
+
+#else
+
+#define static_call(name)						\
+	((typeof(STATIC_CALL_TRAMP(name))*)(STATIC_CALL_KEY(name).func))
+
+#endif /* CONFIG_HAVE_STATIC_CALL */
+
 #endif /* _STATIC_CALL_TYPES_H */