jump_label: Provide CONFIG-driven build state defaults

mainline inclusion
from mainline-v5.13-rc1
commit 0d66ccc1
category: featrue
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YQ6Z
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0d66ccc1627013c95f1e7ef10b95b8451cd7834e

--------------------------------

As shown in the comment in jump_label.h, choosing the initial state of
static branches changes the assembly layout. If the condition is expected
to be likely it's inline, and if unlikely it is out of line via a jump.

A few places in the kernel use (or could be using) a CONFIG to choose the
default state, which would give a small performance benefit to their
compile-time declared default. Provide the infrastructure to do this.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210401232347.2791257-2-keescook@chromium.orgSigned-off-by: NYi Yang <yiyang13@huawei.com>
Reviewed-by: NXiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

include/linux/jump_label.h

@@ -388,6 +388,21 @@ struct static_key_false {
 		[0 ... (count) - 1] = STATIC_KEY_FALSE_INIT,	\
 	}
 
+#define _DEFINE_STATIC_KEY_1(name)	DEFINE_STATIC_KEY_TRUE(name)
+#define _DEFINE_STATIC_KEY_0(name)	DEFINE_STATIC_KEY_FALSE(name)
+#define DEFINE_STATIC_KEY_MAYBE(cfg, name)			\
+	__PASTE(_DEFINE_STATIC_KEY_, IS_ENABLED(cfg))(name)
+
+#define _DEFINE_STATIC_KEY_RO_1(name)	DEFINE_STATIC_KEY_TRUE_RO(name)
+#define _DEFINE_STATIC_KEY_RO_0(name)	DEFINE_STATIC_KEY_FALSE_RO(name)
+#define DEFINE_STATIC_KEY_MAYBE_RO(cfg, name)			\
+	__PASTE(_DEFINE_STATIC_KEY_RO_, IS_ENABLED(cfg))(name)
+
+#define _DECLARE_STATIC_KEY_1(name)	DECLARE_STATIC_KEY_TRUE(name)
+#define _DECLARE_STATIC_KEY_0(name)	DECLARE_STATIC_KEY_FALSE(name)
+#define DECLARE_STATIC_KEY_MAYBE(cfg, name)			\
+	__PASTE(_DECLARE_STATIC_KEY_, IS_ENABLED(cfg))(name)
+
 extern bool ____wrong_branch_error(void);
 
 #define static_key_enabled(x)							\
@@ -488,6 +503,10 @@ extern bool ____wrong_branch_error(void);
 
 #endif /* CONFIG_JUMP_LABEL */
 
+#define static_branch_maybe(config, x)					\
+	(IS_ENABLED(config) ? static_branch_likely(x)			\
+			    : static_branch_unlikely(x))
+
 /*
  * Advanced usage; refcount, branch is enabled when: count != 0
  */