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Commit 080c3747 authored by Vineet Gupta's avatar Vineet Gupta
Browse files

ARC: [optim] Cache "current" in Register r25 



Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 8872e9e5

arch/arc/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -264,6 +264,13 @@ config LINUX_LINK_BASE 


endmenu # "Platform Board Configuration"



config ARC_CURR_IN_REG

	bool "Dedicate Register r25 for current_task pointer"

	default y

	help

	  This reserved Register R25 to point to Current Task in

	  kernel mode. This saves memory access for each such access



config ARC_STACK_NONEXEC

	bool "Make stack non-executable"

	default n

arch/arc/Makefile

+9 −0
Original line number Diff line number Diff line
@@ -20,6 +20,15 @@ export PLATFORM 
cflags-y	+= -Iarch/arc/plat-$(PLATFORM)/include

cflags-y	+= -mA7 -fno-common -pipe -fno-builtin -D__linux__



ifdef CONFIG_ARC_CURR_IN_REG

# For a global register defintion, make sure it gets passed to every file

# We had a customer reported bug where some code built in kernel was NOT using

# any kernel headers, and missing the r25 global register

# Can't do unconditionally (like above) because of recursive include issues

# due to <linux/thread_info.h>

LINUXINCLUDE	+=  -include ${src}/arch/arc/include/asm/current.h

endif



atleast_gcc44 :=  $(call cc-ifversion, -gt, 0402, y)

cflags-$(atleast_gcc44)			+= -fsection-anchors

arch/arc/include/asm/Kbuild

+0 −1
Original line number Diff line number Diff line
@@ -11,7 +11,6 @@ generic-y += bugs.h 
generic-y += bitsperlong.h

generic-y += clkdev.h

generic-y += cputime.h

generic-y += current.h

generic-y += device.h

generic-y += div64.h

generic-y += emergency-restart.h

arch/arc/include/asm/current.h

0 → 100644
+32 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)

 *

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

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * Vineetg: May 16th, 2008

 *  - Current macro is now implemented as "global register" r25

 */



#ifndef _ASM_ARC_CURRENT_H

#define _ASM_ARC_CURRENT_H



#ifdef __KERNEL__



#ifndef __ASSEMBLY__



#ifdef CONFIG_ARC_CURR_IN_REG



register struct task_struct *curr_arc asm("r25");

#define current (curr_arc)



#else

#include <asm-generic/current.h>

#endif /* ! CONFIG_ARC_CURR_IN_REG */



#endif /* ! __ASSEMBLY__ */



#endif	/* __KERNEL__ */



#endif /* _ASM_ARC_CURRENT_H */

arch/arc/include/asm/entry.h

+45 −0
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ 
 *   was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context

 *

 * Vineetg: May 5th 2008

 *  -Modified CALLEE_REG save/restore macros to handle the fact that

 *      r25 contains the kernel current task ptr

 *  - Defined Stack Switching Macro to be reused in all intr/excp hdlrs

 *  - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the

 *      address Write back load ld.ab instead of seperate ld/add instn
@@ -28,6 +30,7 @@ 
#include <asm/asm-offsets.h>

#include <asm/arcregs.h>

#include <asm/ptrace.h>

#include <asm/processor.h>	/* For VMALLOC_START */

#include <asm/thread_info.h>	/* For THREAD_SIZE */



/* Note on the LD/ST addr modes with addr reg wback
@@ -106,7 +109,14 @@ 
	st.a    r22, [sp, -4]

	st.a    r23, [sp, -4]

	st.a    r24, [sp, -4]



#ifdef CONFIG_ARC_CURR_IN_REG

	; Retrieve orig r25 and save it on stack

	ld      r12, [r25, TASK_THREAD + THREAD_USER_R25]

	st.a    r12, [sp, -4]

#else

	st.a    r25, [sp, -4]

#endif



	/* move up by 1 word to "create" callee_regs->"stack_place_holder" */

	sub sp, sp, 4
@@ -131,8 +141,12 @@ 
	st.a    r22, [sp, -4]

	st.a    r23, [sp, -4]

	st.a    r24, [sp, -4]

#ifdef CONFIG_ARC_CURR_IN_REG

	sub     sp, sp, 8

#else

	st.a    r25, [sp, -4]

	sub     sp, sp, 4

#endif

.endm



/*--------------------------------------------------------------
@@ -148,8 +162,14 @@ 
 *-------------------------------------------------------------*/

.macro RESTORE_CALLEE_SAVED_KERNEL





#ifdef CONFIG_ARC_CURR_IN_REG

	add     sp, sp, 8  /* skip callee_reg gutter and user r25 placeholder */

#else

	add     sp, sp, 4   /* skip "callee_regs->stack_place_holder" */

	ld.ab   r25, [sp, 4]

#endif



	ld.ab   r24, [sp, 4]

	ld.ab   r23, [sp, 4]

	ld.ab   r22, [sp, 4]
@@ -235,6 +255,7 @@ 
 *

 * Entry   : r9 contains pre-IRQ/exception/trap status32

 * Exit    : SP is set to kernel mode stack pointer

 *           If CURR_IN_REG, r25 set to "current" task pointer

 * Clobbers: r9

 *-------------------------------------------------------------*/
@@ -259,6 +280,16 @@ 


	GET_CURR_TASK_ON_CPU   r9



#ifdef CONFIG_ARC_CURR_IN_REG



	/* If current task pointer cached in r25, time to

	 *  -safekeep USER r25 in task->thread_struct->user_r25

	 *  -load r25 with current task ptr

	 */

	st.as	r25, [r9, (TASK_THREAD + THREAD_USER_R25)/4]

	mov	r25, r9

#endif



	/* With current tsk in r9, get it's kernel mode stack base */

	GET_TSK_STACK_BASE  r9, r9
@@ -519,17 +550,31 @@ 


.macro  SET_CURR_TASK_ON_CPU    tsk, tmp

	st  \tsk, [@_current_task]

#ifdef CONFIG_ARC_CURR_IN_REG

	mov r25, \tsk

#endif

.endm



/* ------------------------------------------------------------------

 * Get the ptr to some field of Current Task at @off in task struct

 *  -Uses r25 for Current task ptr if that is enabled

 */



#ifdef CONFIG_ARC_CURR_IN_REG



.macro GET_CURR_TASK_FIELD_PTR  off,  reg

	add \reg, r25, \off

.endm



#else



.macro GET_CURR_TASK_FIELD_PTR  off,  reg

	GET_CURR_TASK_ON_CPU  \reg

	add \reg, \reg, \off

.endm



#endif	/* CONFIG_ARC_CURR_IN_REG */



#endif  /* __ASSEMBLY__ */



#endif  /* __ASM_ARC_ENTRY_H */