linux-kernel - [PATCH net-next 1/2] net: add EXPORT_INDIRECT

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Message-Id: <20210204181839.558951-1-brianvv@google.com>
Date:   Thu,  4 Feb 2021 18:18:38 +0000
From:   Brian Vazquez <brianvv@...gle.com>
To:     Brian Vazquez <brianvv.kernel@...il.com>,
        Brian Vazquez <brianvv@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S . Miller" <davem@...emloft.net>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [PATCH net-next 1/2] net: add EXPORT_INDIRECT_CALLABLE wrapper

When a static function is annotated with INDIRECT_CALLABLE_SCOPE and
CONFIG_RETPOLINE is set, the static keyword is removed. Sometimes the
function needs to be exported but EXPORT_SYMBOL can't be used because if
CONFIG_RETPOLINE is not set, we will attempt to export a static symbol.

This patch introduces a new indirect call wrapper:
EXPORT_INDIRECT_CALLABLE. This basically does EXPORT_SYMBOL when
CONFIG_RETPOLINE is set, but does nothing when it's not.

Reported-by: Stephen Rothwell <sfr@...b.auug.org.au>
Signed-off-by: Brian Vazquez <brianvv@...gle.com>
---
 include/linux/indirect_call_wrapper.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/indirect_call_wrapper.h b/include/linux/indirect_call_wrapper.h
index 54c02c84906a..a8345c8a613d 100644
--- a/include/linux/indirect_call_wrapper.h
+++ b/include/linux/indirect_call_wrapper.h
@@ -36,6 +36,7 @@
 
 #define INDIRECT_CALLABLE_DECLARE(f)	f
 #define INDIRECT_CALLABLE_SCOPE
+#define EXPORT_INDIRECT_CALLABLE(f)	EXPORT_SYMBOL(f)
 
 #else
 #define INDIRECT_CALL_1(f, f1, ...) f(__VA_ARGS__)
@@ -44,6 +45,7 @@
 #define INDIRECT_CALL_4(f, f4, f3, f2, f1, ...) f(__VA_ARGS__)
 #define INDIRECT_CALLABLE_DECLARE(f)
 #define INDIRECT_CALLABLE_SCOPE		static
+#define EXPORT_INDIRECT_CALLABLE(f)
 #endif
 
 /*
-- 
2.30.0.365.g02bc693789-goog