Commit 09f05d85 authored by Rabin Vincent's avatar Rabin Vincent Committed by Russell King
Browse files

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: default avatarRabin Vincent <rabin@rab.in>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent a9468f30

arch/arm/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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)

arch/arm/include/asm/jump_label.h

0 → 100644
+41 −0
Original line number Diff line number Diff line 
#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

arch/arm/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/arm/kernel/insn.h

+10 −0
Original line number Diff line number Diff line 
#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);

arch/arm/kernel/jump_label.c

0 → 100644
+39 −0
Original line number Diff line number Diff line 
#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

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