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authorRabin Vincent <rabin@rab.in>2012-02-18 17:52:41 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2012-03-24 09:38:56 +0000
commit09f05d8529ff4aa92311c1a55ce35ac98cb59b8c (patch)
tree0196ddc9e80d74c8d3e3473bd7bc21b3e520c3d9 /arch/arm/include/asm
parenta9468f30b5eac6957c86aea97954553bfb7c1f18 (diff)
ARM: 7334/1: add jump label support
Add the arch-specific code to support jump labels for ARM and Thumb-2. This code will only be activated on compilers that are capable of building it. It has been tested with GCC 4.6 patched with the patch from GCC bug 48637. Cc: Jason Baron <jbaron@redhat.com> Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/include/asm')
-rw-r--r--arch/arm/include/asm/jump_label.h41
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
new file mode 100644
index 00000000000..5c5ca2ea62b
--- /dev/null
+++ b/arch/arm/include/asm/jump_label.h
@@ -0,0 +1,41 @@
+#ifndef _ASM_ARM_JUMP_LABEL_H
+#define _ASM_ARM_JUMP_LABEL_H
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include <asm/system.h>
+
+#define JUMP_LABEL_NOP_SIZE 4
+
+#ifdef CONFIG_THUMB2_KERNEL
+#define JUMP_LABEL_NOP "nop.w"
+#else
+#define JUMP_LABEL_NOP "nop"
+#endif
+
+static __always_inline bool arch_static_branch(struct jump_label_key *key)
+{
+ asm goto("1:\n\t"
+ JUMP_LABEL_NOP "\n\t"
+ ".pushsection __jump_table, \"aw\"\n\t"
+ ".word 1b, %l[l_yes], %c0\n\t"
+ ".popsection\n\t"
+ : : "i" (key) : : l_yes);
+
+ return false;
+l_yes:
+ return true;
+}
+
+#endif /* __KERNEL__ */
+
+typedef u32 jump_label_t;
+
+struct jump_entry {
+ jump_label_t code;
+ jump_label_t target;
+ jump_label_t key;
+};
+
+#endif