[PATCH v10 07/12] static_call: Add EXPORT_STATIC_CALL_FOR_MODULES()

[Pawan Gupta]

There is EXPORT_STATIC_CALL_TRAMP() that hides the static key from all
modules. But there is no equivalent of EXPORT_SYMBOL_FOR_MODULES() to
restrict symbol visibility to only certain modules.

Add EXPORT_STATIC_CALL_FOR_MODULES(name, mods) that wraps both the key and
the trampoline with EXPORT_SYMBOL_FOR_MODULES(), allowing only a limited
set of modules to see and update the static key.

The immediate user is KVM, in the following commit.

checkpatch reported below warnings with this change that I believe don't
apply in this case:

  include/linux/static_call.h:219: WARNING: Non-declarative macros with multiple statements should be enclosed in a do - while loop
  include/linux/static_call.h:220: WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable

Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
---
 include/linux/static_call.h | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/static_call.h b/include/linux/static_call.h
index 78a77a4ae0ea..b610afd1ed55 100644
--- a/include/linux/static_call.h
+++ b/include/linux/static_call.h
@@ -216,6 +216,9 @@ extern long __static_call_return0(void);
 #define EXPORT_STATIC_CALL_GPL(name)					\
 	EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name));			\
 	EXPORT_SYMBOL_GPL(STATIC_CALL_TRAMP(name))
+#define EXPORT_STATIC_CALL_FOR_MODULES(name, mods)			\
+	EXPORT_SYMBOL_FOR_MODULES(STATIC_CALL_KEY(name), mods);		\
+	EXPORT_SYMBOL_FOR_MODULES(STATIC_CALL_TRAMP(name), mods)
 
 /* Leave the key unexported, so modules can't change static call targets: */
 #define EXPORT_STATIC_CALL_TRAMP(name)					\
@@ -276,6 +279,9 @@ extern long __static_call_return0(void);
 #define EXPORT_STATIC_CALL_GPL(name)					\
 	EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name));			\
 	EXPORT_SYMBOL_GPL(STATIC_CALL_TRAMP(name))
+#define EXPORT_STATIC_CALL_FOR_MODULES(name, mods)			\
+	EXPORT_SYMBOL_FOR_MODULES(STATIC_CALL_KEY(name), mods);		\
+	EXPORT_SYMBOL_FOR_MODULES(STATIC_CALL_TRAMP(name), mods)
 
 /* Leave the key unexported, so modules can't change static call targets: */
 #define EXPORT_STATIC_CALL_TRAMP(name)					\
@@ -346,6 +352,8 @@ static inline int static_call_text_reserved(void *start, void *end)
 
 #define EXPORT_STATIC_CALL(name)	EXPORT_SYMBOL(STATIC_CALL_KEY(name))
 #define EXPORT_STATIC_CALL_GPL(name)	EXPORT_SYMBOL_GPL(STATIC_CALL_KEY(name))
+#define EXPORT_STATIC_CALL_FOR_MODULES(name, mods)			\
+	EXPORT_SYMBOL_FOR_MODULES(STATIC_CALL_KEY(name), mods)
 
 #endif /* CONFIG_HAVE_STATIC_CALL */
 

-- 
2.34.1