From 080c37473eb671a037b3e9a315303851f0675be5 Mon Sep 17 00:00:00 2001 From: Vineet Gupta Date: Mon, 11 Feb 2013 19:52:57 +0530 Subject: [PATCH] ARC: [optim] Cache "current" in Register r25 Signed-off-by: Vineet Gupta --- arch/arc/Kconfig | 7 +++++ arch/arc/Makefile | 9 +++++++ arch/arc/include/asm/Kbuild | 1 - arch/arc/include/asm/current.h | 32 +++++++++++++++++++++++ arch/arc/include/asm/entry.h | 45 ++++++++++++++++++++++++++++++++ arch/arc/include/asm/processor.h | 3 +++ arch/arc/kernel/asm-offsets.c | 3 +++ arch/arc/kernel/ctx_sw.c | 7 +++++ arch/arc/kernel/entry.S | 14 ++++++++++ 9 files changed, 120 insertions(+), 1 deletion(-) create mode 100644 arch/arc/include/asm/current.h diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig index 7db978570fb8..03347cbde9bd 100644 --- a/arch/arc/Kconfig +++ b/arch/arc/Kconfig @@ -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 diff --git a/arch/arc/Makefile b/arch/arc/Makefile index 29b5fcd9c4b6..5c98fc19d99d 100644 --- a/arch/arc/Makefile +++ b/arch/arc/Makefile @@ -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 +LINUXINCLUDE += -include ${src}/arch/arc/include/asm/current.h +endif + atleast_gcc44 := $(call cc-ifversion, -gt, 0402, y) cflags-$(atleast_gcc44) += -fsection-anchors diff --git a/arch/arc/include/asm/Kbuild b/arch/arc/include/asm/Kbuild index 105ec1188aaf..78e982dad537 100644 --- a/arch/arc/include/asm/Kbuild +++ b/arch/arc/include/asm/Kbuild @@ -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 diff --git a/arch/arc/include/asm/current.h b/arch/arc/include/asm/current.h new file mode 100644 index 000000000000..87b918585c4a --- /dev/null +++ b/arch/arc/include/asm/current.h @@ -0,0 +1,32 @@ +/* + * 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 +#endif /* ! CONFIG_ARC_CURR_IN_REG */ + +#endif /* ! __ASSEMBLY__ */ + +#endif /* __KERNEL__ */ + +#endif /* _ASM_ARC_CURRENT_H */ diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h index 9eada5b28be6..716f4f7b5cd2 100644 --- a/arch/arc/include/asm/entry.h +++ b/arch/arc/include/asm/entry.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 #include #include +#include /* For VMALLOC_START */ #include /* 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 */ diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h index 860252ec3fa7..b7b155610067 100644 --- a/arch/arc/include/asm/processor.h +++ b/arch/arc/include/asm/processor.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 diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c index d7770cc9aee3..0dc148ebce74 100644 --- a/arch/arc/kernel/asm-offsets.c +++ b/arch/arc/kernel/asm-offsets.c @@ -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)); diff --git a/arch/arc/kernel/ctx_sw.c b/arch/arc/kernel/ctx_sw.c index 647e37a5165e..fbf739cbaf7d 100644 --- a/arch/arc/kernel/ctx_sw.c +++ b/arch/arc/kernel/ctx_sw.c @@ -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" diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S index ce8670da8306..69d0d376e28b 100644 --- a/arch/arc/kernel/entry.S +++ b/arch/arc/kernel/entry.S @@ -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