jump_label: Abstract jump_entry member accessors

In preparation of allowing architectures to use relative references
in jump_label entries [which can dramatically reduce the memory
footprint], introduce abstractions for references to the 'code' and
'key' members of struct jump_entry.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Jessica Yu <jeyu@kernel.org>
Link: https://lkml.kernel.org/r/20180919065144.25010-2-ard.biesheuvel@linaro.org

1 files changed, 34 insertions, 0 deletions

diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h
index 1a0b6f17a5d6..2eadff9b3b90 100644
--- a/include/linux/jump_label.h
+++ b/include/linux/jump_label.h
@@ -119,6 +119,40 @@ struct static_key {
 
 #ifdef HAVE_JUMP_LABEL
 #include <asm/jump_label.h>
+
+#ifndef __ASSEMBLY__
+
+static inline unsigned long jump_entry_code(const struct jump_entry *entry)
+{
+	return entry->code;
+}
+
+static inline unsigned long jump_entry_target(const struct jump_entry *entry)
+{
+	return entry->target;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+	return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+	return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_init(const struct jump_entry *entry)
+{
+	return entry->code == 0;
+}
+
+static inline void jump_entry_set_init(struct jump_entry *entry)
+{
+	entry->code = 0;
+}
+
+#endif
 #endif
 
 #ifndef __ASSEMBLY__