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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
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>
-rw-r--r--arch/arm/Kconfig1
-rw-r--r--arch/arm/include/asm/jump_label.h41
-rw-r--r--arch/arm/kernel/Makefile1
-rw-r--r--arch/arm/kernel/insn.h10
-rw-r--r--arch/arm/kernel/jump_label.c39
5 files changed, 92 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 6b5f84887ce..ee6c7154c9a 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -9,6 +9,7 @@ config ARM
select SYS_SUPPORTS_APM_EMULATION
select GENERIC_ATOMIC64 if (CPU_V6 || !CPU_32v6K || !AEABI)
select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
+ select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
select HAVE_ARCH_KGDB
select HAVE_KPROBES if !XIP_KERNEL
select HAVE_KRETPROBES if (HAVE_KPROBES)
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
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 8c63ee8d3c4..1b7d9a39097 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -38,6 +38,7 @@ obj-$(CONFIG_HAVE_ARM_SCU) += smp_scu.o
obj-$(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 994d60fd3ff..e96065da4da 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 00000000000..4ce4f789446
--- /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