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>

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>
Rabin Vincent · Russell King
1 parent a9468f30b5
Showing 5 changed files with 92 additions and 0 deletions Side-by-side Diff
arch/arm/Kconfig
arch/arm/include/asm/jump_label.h
arch/arm/kernel/Makefile
arch/arm/kernel/insn.h
arch/arm/kernel/jump_label.c
@@ -9,6 +9,7 @@
 	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)
+#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
@@ -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
 #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);
  
+#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
...	...	@@ -9,6 +9,7 @@
9	9	select SYS_SUPPORTS_APM_EMULATION
10	10	select GENERIC_ATOMIC64 if (CPU_V6 \|\| !CPU_32v6K \|\| !AEABI)
11	11	select HAVE_OPROFILE if (HAVE_PERF_EVENTS)
	12	+ select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
12	13	select HAVE_ARCH_KGDB
13	14	select HAVE_KPROBES if !XIP_KERNEL
14	15	select HAVE_KRETPROBES if (HAVE_KPROBES)
	1	+#ifndef _ASM_ARM_JUMP_LABEL_H
	2	+#define _ASM_ARM_JUMP_LABEL_H
	3	+
	4	+#ifdef __KERNEL__
	5	+
	6	+#include <linux/types.h>
	7	+#include <asm/system.h>
	8	+
	9	+#define JUMP_LABEL_NOP_SIZE 4
	10	+
	11	+#ifdef CONFIG_THUMB2_KERNEL
	12	+#define JUMP_LABEL_NOP "nop.w"
	13	+#else
	14	+#define JUMP_LABEL_NOP "nop"
	15	+#endif
	16	+
	17	+static __always_inline bool arch_static_branch(struct jump_label_key *key)
	18	+{
	19	+ asm goto("1:\n\t"
	20	+ JUMP_LABEL_NOP "\n\t"
	21	+ ".pushsection __jump_table, \"aw\"\n\t"
	22	+ ".word 1b, %l[l_yes], %c0\n\t"
	23	+ ".popsection\n\t"
	24	+ : : "i" (key) : : l_yes);
	25	+
	26	+ return false;
	27	+l_yes:
	28	+ return true;
	29	+}
	30	+
	31	+#endif /* __KERNEL__ */
	32	+
	33	+typedef u32 jump_label_t;
	34	+
	35	+struct jump_entry {
	36	+ jump_label_t code;
	37	+ jump_label_t target;
	38	+ jump_label_t key;
	39	+};
	40	+
	41	+#endif
...	...	@@ -38,6 +38,7 @@
38	38	obj-$(CONFIG_HAVE_ARM_TWD) += smp_twd.o
39	39	obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o insn.o
40	40	obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o insn.o
	41	+obj-$(CONFIG_JUMP_LABEL) += jump_label.o insn.o patch.o
41	42	obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
42	43	obj-$(CONFIG_KPROBES) += kprobes.o kprobes-common.o patch.o
43	44	ifdef CONFIG_THUMB2_KERNEL
1	1	#ifndef __ASM_ARM_INSN_H
2	2	#define __ASM_ARM_INSN_H
3	3
	4	+static inline unsigned long
	5	+arm_gen_nop(void)
	6	+{
	7	+#ifdef CONFIG_THUMB2_KERNEL
	8	+ return 0xf3af8000; /* nop.w */
	9	+#else
	10	+ return 0xe1a00000; /* mov r0, r0 */
	11	+#endif
	12	+}
	13	+
4	14	unsigned long
5	15	__arm_gen_branch(unsigned long pc, unsigned long addr, bool link);
6	16
	1	+#include <linux/kernel.h>
	2	+#include <linux/jump_label.h>
	3	+
	4	+#include "insn.h"
	5	+#include "patch.h"
	6	+
	7	+#ifdef HAVE_JUMP_LABEL
	8	+
	9	+static void __arch_jump_label_transform(struct jump_entry *entry,
	10	+ enum jump_label_type type,
	11	+ bool is_static)
	12	+{
	13	+ void addr = (void )entry->code;
	14	+ unsigned int insn;
	15	+
	16	+ if (type == JUMP_LABEL_ENABLE)
	17	+ insn = arm_gen_branch(entry->code, entry->target);
	18	+ else
	19	+ insn = arm_gen_nop();
	20	+
	21	+ if (is_static)
	22	+ __patch_text(addr, insn);
	23	+ else
	24	+ patch_text(addr, insn);
	25	+}
	26	+
	27	+void arch_jump_label_transform(struct jump_entry *entry,
	28	+ enum jump_label_type type)
	29	+{
	30	+ __arch_jump_label_transform(entry, type, false);
	31	+}
	32	+
	33	+void arch_jump_label_transform_static(struct jump_entry *entry,
	34	+ enum jump_label_type type)
	35	+{
	36	+ __arch_jump_label_transform(entry, type, true);
	37	+}
	38	+
	39	+#endif