From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/arc/kernel/ctx_sw_asm.S | 65 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 arch/arc/kernel/ctx_sw_asm.S (limited to 'arch/arc/kernel/ctx_sw_asm.S') diff --git a/arch/arc/kernel/ctx_sw_asm.S b/arch/arc/kernel/ctx_sw_asm.S new file mode 100644 index 000000000..e24859409 --- /dev/null +++ b/arch/arc/kernel/ctx_sw_asm.S @@ -0,0 +1,65 @@ +/* + * 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: Aug 2009 + * -Moved core context switch macro out of entry.S into this file. + * -This is the more "natural" hand written assembler + */ + +#include +#include /* For the SAVE_* macros */ +#include + +#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4) + +;################### Low Level Context Switch ########################## + + .section .sched.text,"ax",@progbits + .align 4 + .global __switch_to + .type __switch_to, @function +__switch_to: + + /* Save regs on kernel mode stack of task */ + st.a blink, [sp, -4] + st.a fp, [sp, -4] + SAVE_CALLEE_SAVED_KERNEL + + /* Save the now KSP in task->thread.ksp */ +#if KSP_WORD_OFF <= 255 + st.as sp, [r0, KSP_WORD_OFF] +#else + /* Workaround for NR_CPUS=4k as ST.as can only take s9 offset */ + add2 r24, r0, KSP_WORD_OFF + st sp, [r24] +#endif + /* + * Return last task in r0 (return reg) + * On ARC, Return reg = First Arg reg = r0. + * Since we already have last task in r0, + * don't need to do anything special to return it + */ + + /* hardware memory barrier */ + sync + + /* + * switch to new task, contained in r1 + * Temp reg r3 is required to get the ptr to store val + */ + SET_CURR_TASK_ON_CPU r1, r3 + + /* reload SP with kernel mode stack pointer in task->thread.ksp */ + ld.as sp, [r1, (TASK_THREAD + THREAD_KSP)/4] + + /* restore the registers */ + RESTORE_CALLEE_SAVED_KERNEL + ld.ab fp, [sp, 4] + ld.ab blink, [sp, 4] + j [blink] + +END(__switch_to) -- cgit v1.2.3-54-g00ecf