Commit ac5f89c7 authored by Michael Ellerman's avatar Michael Ellerman Committed by Benjamin Herrenschmidt
Browse files

powerpc: Add jump label support 



This patch adds support for the new "jump label" feature.

Unlike x86 and sparc we just merrily patch the code with no locks etc,
as far as I know this is safe, but I'm not really sure what the x86/sparc
code is protecting against so maybe it's not.

I also don't see any reason for us to implement the poke_early() routine,
even though sparc does.

[BenH: Updated the patch to upstream generic changes]

Signed-off-by: default avatarMichael Ellerman <michael@ellerman.id.au>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 87fa35dd

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -134,6 +134,7 @@ config PPC 
	select GENERIC_IRQ_SHOW_LEVEL

	select HAVE_RCU_TABLE_FREE if SMP

	select HAVE_SYSCALL_TRACEPOINTS

	select HAVE_ARCH_JUMP_LABEL



config EARLY_PRINTK

	bool

arch/powerpc/include/asm/jump_label.h

0 → 100644
+47 −0
Original line number Diff line number Diff line 
#ifndef _ASM_POWERPC_JUMP_LABEL_H

#define _ASM_POWERPC_JUMP_LABEL_H



/*

 * Copyright 2010 Michael Ellerman, IBM Corp.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */



#include <linux/types.h>



#include <asm/feature-fixups.h>



#define JUMP_ENTRY_TYPE		stringify_in_c(FTR_ENTRY_LONG)

#define JUMP_LABEL_NOP_SIZE	4



static __always_inline bool arch_static_branch(struct jump_label_key *key)

{

	asm goto("1:\n\t"

		 "nop\n\t"

		 ".pushsection __jump_table,  \"aw\"\n\t"

		 ".align 4\n\t"

		 JUMP_ENTRY_TYPE "1b, %l[l_yes], %c0\n\t"

		 ".popsection \n\t"

		 : :  "i" (key) : : l_yes);

	return false;

l_yes:

	return true;

}



#ifdef CONFIG_PPC64

typedef u64 jump_label_t;

#else

typedef u32 jump_label_t;

#endif



struct jump_entry {

	jump_label_t code;

	jump_label_t target;

	jump_label_t key;

	jump_label_t pad;

};



#endif /* _ASM_POWERPC_JUMP_LABEL_H */

arch/powerpc/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -76,6 +76,7 @@ obj-$(CONFIG_MODULES) += module.o module_$(CONFIG_WORD_SIZE).o 
obj-$(CONFIG_44x)		+= cpu_setup_44x.o

obj-$(CONFIG_PPC_FSL_BOOK3E)	+= cpu_setup_fsl_booke.o dbell.o

obj-$(CONFIG_PPC_BOOK3E_64)	+= dbell.o

obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o



extra-y				:= head_$(CONFIG_WORD_SIZE).o

extra-$(CONFIG_40x)		:= head_40x.o

arch/powerpc/kernel/jump_label.c

0 → 100644
+23 −0
Original line number Diff line number Diff line 
/*

 * Copyright 2010 Michael Ellerman, IBM Corp.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version

 * 2 of the License, or (at your option) any later version.

 */



#include <linux/kernel.h>

#include <linux/jump_label.h>

#include <asm/code-patching.h>



void arch_jump_label_transform(struct jump_entry *entry,

			       enum jump_label_type type)

{

	u32 *addr = (u32 *)(unsigned long)entry->code;



	if (type == JUMP_LABEL_ENABLE)

		patch_branch(addr, entry->target, 0);

	else

		patch_instruction(addr, PPC_INST_NOP);

}

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