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

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

Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent 8872e9e5
......@@ -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
......
......@@ -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
......
......@@ -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
......
/*
* 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 */
......@@ -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 */
......@@ -29,6 +29,9 @@ struct thread_struct {
unsigned long callee_reg; /* pointer to callee regs */
unsigned long fault_address; /* dbls as brkpt holder as well */
unsigned long cause_code; /* Exception Cause Code (ECR) */
#ifdef CONFIG_ARC_CURR_IN_REG
unsigned long user_r25;
#endif
#ifdef CONFIG_ARC_FPU_SAVE_RESTORE
struct arc_fpu fpu;
#endif
......
......@@ -24,6 +24,9 @@ int main(void)
DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
DEFINE(THREAD_CALLEE_REG, offsetof(struct thread_struct, callee_reg));
#ifdef CONFIG_ARC_CURR_IN_REG
DEFINE(THREAD_USER_R25, offsetof(struct thread_struct, user_r25));
#endif
DEFINE(THREAD_FAULT_ADDR,
offsetof(struct thread_struct, fault_address));
......
......@@ -24,6 +24,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
unsigned int prev = (unsigned int)prev_task;
unsigned int next = (unsigned int)next_task;
int num_words_to_skip = 1;
#ifdef CONFIG_ARC_CURR_IN_REG
num_words_to_skip++;
#endif
__asm__ __volatile__(
/* FP/BLINK save generated by gcc (standard function prologue */
......@@ -39,7 +42,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
"st.a r22, [sp, -4] \n\t"
"st.a r23, [sp, -4] \n\t"
"st.a r24, [sp, -4] \n\t"
#ifndef CONFIG_ARC_CURR_IN_REG
"st.a r25, [sp, -4] \n\t"
#endif
"sub sp, sp, %4 \n\t" /* create gutter at top */
/* set ksp of outgoing task in tsk->thread.ksp */
......@@ -62,7 +67,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
"add sp, sp, %4 \n\t" /* skip gutter at top */
#ifndef CONFIG_ARC_CURR_IN_REG
"ld.ab r25, [sp, 4] \n\t"
#endif
"ld.ab r24, [sp, 4] \n\t"
"ld.ab r23, [sp, 4] \n\t"
"ld.ab r22, [sp, 4] \n\t"
......
......@@ -32,6 +32,9 @@
* was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit,
* setting it and not clearing it clears ZOL context
*
* Vineetg: May 16th, 2008
* - r25 now contains the Current Task when in kernel
*
* Vineetg: Dec 22, 2007
* Minor Surgery of Low Level ISR to make it SMP safe
* - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
......@@ -535,6 +538,17 @@ restore_regs :
; XXX can this be optimised out
IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
#ifdef CONFIG_ARC_CURR_IN_REG
; Restore User R25
; Earlier this used to be only for returning to user mode
; However with 2 levels of IRQ this can also happen even if
; in kernel mode
ld r9, [sp, PT_sp]
brhs r9, VMALLOC_START, 8f
RESTORE_USER_R25
8:
#endif
; Restore REG File. In case multiple Events outstanding,
; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
; Note that we use realtime STATUS32 (not pt_regs->status32) to
......
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