ARC: [optim] Cache "current" in Register r25
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta
parent
8872e9e513
commit
080c37473e
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@ -264,6 +264,13 @@ config LINUX_LINK_BASE
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endmenu # "Platform Board Configuration"
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config ARC_CURR_IN_REG
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bool "Dedicate Register r25 for current_task pointer"
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default y
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help
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This reserved Register R25 to point to Current Task in
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kernel mode. This saves memory access for each such access
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config ARC_STACK_NONEXEC
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bool "Make stack non-executable"
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default n
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@ -20,6 +20,15 @@ export PLATFORM
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cflags-y += -Iarch/arc/plat-$(PLATFORM)/include
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cflags-y += -mA7 -fno-common -pipe -fno-builtin -D__linux__
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ifdef CONFIG_ARC_CURR_IN_REG
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# For a global register defintion, make sure it gets passed to every file
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# We had a customer reported bug where some code built in kernel was NOT using
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# any kernel headers, and missing the r25 global register
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# Can't do unconditionally (like above) because of recursive include issues
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# due to <linux/thread_info.h>
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LINUXINCLUDE += -include ${src}/arch/arc/include/asm/current.h
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endif
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atleast_gcc44 := $(call cc-ifversion, -gt, 0402, y)
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cflags-$(atleast_gcc44) += -fsection-anchors
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@ -11,7 +11,6 @@ generic-y += bugs.h
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generic-y += bitsperlong.h
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generic-y += clkdev.h
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generic-y += cputime.h
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generic-y += current.h
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generic-y += device.h
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generic-y += div64.h
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generic-y += emergency-restart.h
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32
arch/arc/include/asm/current.h
Normal file
32
arch/arc/include/asm/current.h
Normal file
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@ -0,0 +1,32 @@
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/*
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Vineetg: May 16th, 2008
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* - Current macro is now implemented as "global register" r25
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*/
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#ifndef _ASM_ARC_CURRENT_H
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#define _ASM_ARC_CURRENT_H
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#ifdef __KERNEL__
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_ARC_CURR_IN_REG
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register struct task_struct *curr_arc asm("r25");
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#define current (curr_arc)
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#else
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#include <asm-generic/current.h>
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#endif /* ! CONFIG_ARC_CURR_IN_REG */
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#endif /* ! __ASSEMBLY__ */
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#endif /* __KERNEL__ */
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#endif /* _ASM_ARC_CURRENT_H */
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@ -13,6 +13,8 @@
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* was being "CLEARED" rather then "SET". Actually "SET" clears ZOL context
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*
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* Vineetg: May 5th 2008
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* -Modified CALLEE_REG save/restore macros to handle the fact that
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* r25 contains the kernel current task ptr
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* - Defined Stack Switching Macro to be reused in all intr/excp hdlrs
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* - Shaved off 11 instructions from RESTORE_ALL_INT1 by using the
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* address Write back load ld.ab instead of seperate ld/add instn
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@ -28,6 +30,7 @@
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#include <asm/asm-offsets.h>
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#include <asm/arcregs.h>
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#include <asm/ptrace.h>
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#include <asm/processor.h> /* For VMALLOC_START */
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#include <asm/thread_info.h> /* For THREAD_SIZE */
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/* Note on the LD/ST addr modes with addr reg wback
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@ -106,7 +109,14 @@
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st.a r22, [sp, -4]
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st.a r23, [sp, -4]
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st.a r24, [sp, -4]
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#ifdef CONFIG_ARC_CURR_IN_REG
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; Retrieve orig r25 and save it on stack
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ld r12, [r25, TASK_THREAD + THREAD_USER_R25]
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st.a r12, [sp, -4]
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#else
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st.a r25, [sp, -4]
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#endif
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/* move up by 1 word to "create" callee_regs->"stack_place_holder" */
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sub sp, sp, 4
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@ -131,8 +141,12 @@
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st.a r22, [sp, -4]
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st.a r23, [sp, -4]
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st.a r24, [sp, -4]
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#ifdef CONFIG_ARC_CURR_IN_REG
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sub sp, sp, 8
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#else
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st.a r25, [sp, -4]
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sub sp, sp, 4
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#endif
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.endm
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/*--------------------------------------------------------------
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@ -148,8 +162,14 @@
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*-------------------------------------------------------------*/
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.macro RESTORE_CALLEE_SAVED_KERNEL
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#ifdef CONFIG_ARC_CURR_IN_REG
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add sp, sp, 8 /* skip callee_reg gutter and user r25 placeholder */
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#else
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add sp, sp, 4 /* skip "callee_regs->stack_place_holder" */
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ld.ab r25, [sp, 4]
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#endif
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ld.ab r24, [sp, 4]
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ld.ab r23, [sp, 4]
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ld.ab r22, [sp, 4]
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@ -235,6 +255,7 @@
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*
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* Entry : r9 contains pre-IRQ/exception/trap status32
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* Exit : SP is set to kernel mode stack pointer
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* If CURR_IN_REG, r25 set to "current" task pointer
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* Clobbers: r9
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*-------------------------------------------------------------*/
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@ -259,6 +280,16 @@
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GET_CURR_TASK_ON_CPU r9
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#ifdef CONFIG_ARC_CURR_IN_REG
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/* If current task pointer cached in r25, time to
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* -safekeep USER r25 in task->thread_struct->user_r25
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* -load r25 with current task ptr
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*/
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st.as r25, [r9, (TASK_THREAD + THREAD_USER_R25)/4]
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mov r25, r9
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#endif
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/* With current tsk in r9, get it's kernel mode stack base */
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GET_TSK_STACK_BASE r9, r9
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@ -519,17 +550,31 @@
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.macro SET_CURR_TASK_ON_CPU tsk, tmp
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st \tsk, [@_current_task]
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#ifdef CONFIG_ARC_CURR_IN_REG
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mov r25, \tsk
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#endif
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.endm
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/* ------------------------------------------------------------------
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* Get the ptr to some field of Current Task at @off in task struct
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* -Uses r25 for Current task ptr if that is enabled
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*/
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#ifdef CONFIG_ARC_CURR_IN_REG
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.macro GET_CURR_TASK_FIELD_PTR off, reg
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add \reg, r25, \off
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.endm
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#else
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.macro GET_CURR_TASK_FIELD_PTR off, reg
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GET_CURR_TASK_ON_CPU \reg
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add \reg, \reg, \off
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.endm
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#endif /* CONFIG_ARC_CURR_IN_REG */
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_ARC_ENTRY_H */
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@ -29,6 +29,9 @@ struct thread_struct {
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unsigned long callee_reg; /* pointer to callee regs */
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unsigned long fault_address; /* dbls as brkpt holder as well */
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unsigned long cause_code; /* Exception Cause Code (ECR) */
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#ifdef CONFIG_ARC_CURR_IN_REG
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unsigned long user_r25;
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#endif
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#ifdef CONFIG_ARC_FPU_SAVE_RESTORE
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struct arc_fpu fpu;
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#endif
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@ -24,6 +24,9 @@ int main(void)
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DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
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DEFINE(THREAD_CALLEE_REG, offsetof(struct thread_struct, callee_reg));
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#ifdef CONFIG_ARC_CURR_IN_REG
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DEFINE(THREAD_USER_R25, offsetof(struct thread_struct, user_r25));
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#endif
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DEFINE(THREAD_FAULT_ADDR,
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offsetof(struct thread_struct, fault_address));
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@ -24,6 +24,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
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unsigned int prev = (unsigned int)prev_task;
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unsigned int next = (unsigned int)next_task;
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int num_words_to_skip = 1;
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#ifdef CONFIG_ARC_CURR_IN_REG
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num_words_to_skip++;
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#endif
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__asm__ __volatile__(
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/* FP/BLINK save generated by gcc (standard function prologue */
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@ -39,7 +42,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
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"st.a r22, [sp, -4] \n\t"
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"st.a r23, [sp, -4] \n\t"
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"st.a r24, [sp, -4] \n\t"
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#ifndef CONFIG_ARC_CURR_IN_REG
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"st.a r25, [sp, -4] \n\t"
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#endif
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"sub sp, sp, %4 \n\t" /* create gutter at top */
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/* set ksp of outgoing task in tsk->thread.ksp */
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@ -62,7 +67,9 @@ __switch_to(struct task_struct *prev_task, struct task_struct *next_task)
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"add sp, sp, %4 \n\t" /* skip gutter at top */
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#ifndef CONFIG_ARC_CURR_IN_REG
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"ld.ab r25, [sp, 4] \n\t"
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#endif
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"ld.ab r24, [sp, 4] \n\t"
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"ld.ab r23, [sp, 4] \n\t"
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"ld.ab r22, [sp, 4] \n\t"
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@ -32,6 +32,9 @@
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* was being "CLEARED" rather then "SET". Since it is Loop INHIBIT Bit,
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* setting it and not clearing it clears ZOL context
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*
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* Vineetg: May 16th, 2008
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* - r25 now contains the Current Task when in kernel
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*
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* Vineetg: Dec 22, 2007
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* Minor Surgery of Low Level ISR to make it SMP safe
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* - MMU_SCRATCH0 Reg used for freeing up r9 in Level 1 ISR
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@ -535,6 +538,17 @@ restore_regs :
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; XXX can this be optimised out
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IRQ_DISABLE_SAVE r9, r10 ;@r10 has prisitine (pre-disable) copy
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#ifdef CONFIG_ARC_CURR_IN_REG
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; Restore User R25
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; Earlier this used to be only for returning to user mode
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; However with 2 levels of IRQ this can also happen even if
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; in kernel mode
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ld r9, [sp, PT_sp]
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brhs r9, VMALLOC_START, 8f
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RESTORE_USER_R25
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8:
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#endif
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; Restore REG File. In case multiple Events outstanding,
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; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
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; Note that we use realtime STATUS32 (not pt_regs->status32) to
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