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>
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 8c63ee8..1b7d9a3 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -38,6 +38,7 @@
obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o
obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o
+obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
obj-$(CONFIG_KPROBES) += kprobes.o kprobes-common.o patch.o
ifdef CONFIG_THUMB2_KERNEL
diff --git a/arch/arm/kernel/insn.h b/arch/arm/kernel/insn.h
index 994d60f..e96065d 100644
--- a/arch/arm/kernel/insn.h
+++ b/arch/arm/kernel/insn.h
@@ -1,6 +1,16 @@
#ifndef __ASM_ARM_INSN_H
#define __ASM_ARM_INSN_H
+static inline unsigned long
+arm_gen_nop(void)
+{
+#ifdef CONFIG_THUMB2_KERNEL
+ return 0xf3af8000; /* nop.w */
+#else
+ return 0xe1a00000; /* mov r0, r0 */
+#endif
+}
+
unsigned long
__arm_gen_branch(unsigned long pc, unsigned long addr, bool link);
diff --git a/arch/arm/kernel/jump_label.c b/arch/arm/kernel/jump_label.c
new file mode 100644
index 0000000..4ce4f78
--- /dev/null
+++ b/arch/arm/kernel/jump_label.c
@@ -0,0 +1,39 @@
+#include <linux/kernel.h>
+#include <linux/jump_label.h>
+
+#include "insn.h"
+#include "patch.h"
+
+#ifdef HAVE_JUMP_LABEL
+
+static void __arch_jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type,
+ bool is_static)
+{
+ void *addr = (void *)entry->code;
+ unsigned int insn;
+
+ if (type == JUMP_LABEL_ENABLE)
+ insn = arm_gen_branch(entry->code, entry->target);
+ else
+ insn = arm_gen_nop();
+
+ if (is_static)
+ __patch_text(addr, insn);
+ else
+ patch_text(addr, insn);
+}
+
+void arch_jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ __arch_jump_label_transform(entry, type, false);
+}
+
+void arch_jump_label_transform_static(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ __arch_jump_label_transform(entry, type, true);
+}
+
+#endif