1bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta/* 2bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) 3bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * 4bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * This program is free software; you can redistribute it and/or modify 5bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * it under the terms of the GNU General Public License version 2 as 6bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * published by the Free Software Foundation. 7bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * 8bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * Vineetg: Aug 2009 9bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * -"C" version of lowest level context switch asm macro called by schedular 10bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * gcc doesn't generate the dward CFI info for hand written asm, hence can't 11bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * backtrace out of it (e.g. tasks sleeping in kernel). 12bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * So we cheat a bit by writing almost similar code in inline-asm. 13bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * -This is a hacky way of doing things, but there is no other simple way. 14bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * I don't want/intend to extend unwinding code to understand raw asm 15bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta */ 16bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 17bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta#include <asm/asm-offsets.h> 18bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta#include <linux/sched.h> 19bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 2057e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4) 2157e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta 22bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Guptastruct task_struct *__sched 23bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta__switch_to(struct task_struct *prev_task, struct task_struct *next_task) 24bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta{ 25bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta unsigned int tmp; 26bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta unsigned int prev = (unsigned int)prev_task; 27bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta unsigned int next = (unsigned int)next_task; 28bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 29bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta __asm__ __volatile__( 30bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* FP/BLINK save generated by gcc (standard function prologue */ 31bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r13, [sp, -4] \n\t" 32bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r14, [sp, -4] \n\t" 33bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r15, [sp, -4] \n\t" 34bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r16, [sp, -4] \n\t" 35bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r17, [sp, -4] \n\t" 36bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r18, [sp, -4] \n\t" 37bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r19, [sp, -4] \n\t" 38bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r20, [sp, -4] \n\t" 39bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r21, [sp, -4] \n\t" 40bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r22, [sp, -4] \n\t" 41bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r23, [sp, -4] \n\t" 42bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r24, [sp, -4] \n\t" 43080c37473eb671a037b3e9a315303851f0675be5Vineet Gupta#ifndef CONFIG_ARC_CURR_IN_REG 44bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.a r25, [sp, -4] \n\t" 4516f9afe651e8197fb7ce6df0990d8e2ad779e1afVineet Gupta#else 4616f9afe651e8197fb7ce6df0990d8e2ad779e1afVineet Gupta "sub sp, sp, 4 \n\t" /* usual r25 placeholder */ 47080c37473eb671a037b3e9a315303851f0675be5Vineet Gupta#endif 48bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 49bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* set ksp of outgoing task in tsk->thread.ksp */ 5057e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta#if KSP_WORD_OFF <= 255 51bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st.as sp, [%3, %1] \n\t" 5257e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta#else 5357e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta /* 5457e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta * Workaround for NR_CPUS=4k 5557e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta * %1 is bigger than 255 (S9 offset for st.as) 5657e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta */ 5757e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta "add2 r24, %3, %1 \n\t" 5857e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta "st sp, [r24] \n\t" 5957e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta#endif 60bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 61bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "sync \n\t" 62bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 63bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* 64bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * setup _current_task with incoming tsk. 65bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * optionally, set r25 to that as well 66bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * For SMP extra work to get to &_current_task[cpu] 67bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta * (open coded SET_CURR_TASK_ON_CPU) 68bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta */ 6941195d236e84458bebd4fdc218610a92231ac791Vineet Gupta#ifndef CONFIG_SMP 70bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "st %2, [@_current_task] \n\t" 7141195d236e84458bebd4fdc218610a92231ac791Vineet Gupta#else 7241195d236e84458bebd4fdc218610a92231ac791Vineet Gupta "lr r24, [identity] \n\t" 7341195d236e84458bebd4fdc218610a92231ac791Vineet Gupta "lsr r24, r24, 8 \n\t" 7441195d236e84458bebd4fdc218610a92231ac791Vineet Gupta "bmsk r24, r24, 7 \n\t" 7541195d236e84458bebd4fdc218610a92231ac791Vineet Gupta "add2 r24, @_current_task, r24 \n\t" 7641195d236e84458bebd4fdc218610a92231ac791Vineet Gupta "st %2, [r24] \n\t" 7741195d236e84458bebd4fdc218610a92231ac791Vineet Gupta#endif 7841195d236e84458bebd4fdc218610a92231ac791Vineet Gupta#ifdef CONFIG_ARC_CURR_IN_REG 7941195d236e84458bebd4fdc218610a92231ac791Vineet Gupta "mov r25, %2 \n\t" 8041195d236e84458bebd4fdc218610a92231ac791Vineet Gupta#endif 81bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 82bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* get ksp of incoming task from tsk->thread.ksp */ 83bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.as sp, [%2, %1] \n\t" 84bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 85bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* start loading it's CALLEE reg file */ 86bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 87080c37473eb671a037b3e9a315303851f0675be5Vineet Gupta#ifndef CONFIG_ARC_CURR_IN_REG 88bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r25, [sp, 4] \n\t" 8916f9afe651e8197fb7ce6df0990d8e2ad779e1afVineet Gupta#else 9016f9afe651e8197fb7ce6df0990d8e2ad779e1afVineet Gupta "add sp, sp, 4 \n\t" 91080c37473eb671a037b3e9a315303851f0675be5Vineet Gupta#endif 92bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r24, [sp, 4] \n\t" 93bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r23, [sp, 4] \n\t" 94bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r22, [sp, 4] \n\t" 95bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r21, [sp, 4] \n\t" 96bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r20, [sp, 4] \n\t" 97bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r19, [sp, 4] \n\t" 98bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r18, [sp, 4] \n\t" 99bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r17, [sp, 4] \n\t" 100bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r16, [sp, 4] \n\t" 101bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r15, [sp, 4] \n\t" 102bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r14, [sp, 4] \n\t" 103bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "ld.ab r13, [sp, 4] \n\t" 104bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 105bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* last (ret value) = prev : although for ARC it mov r0, r0 */ 106bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta "mov %0, %3 \n\t" 107bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 108bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta /* FP/BLINK restore generated by gcc (standard func epilogue */ 109bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 110bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta : "=r"(tmp) 11157e26e57454fae4f1d15c2e9fa965b7a8046ab34Vineet Gupta : "n"(KSP_WORD_OFF), "r"(next), "r"(prev) 112bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta : "blink" 113bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta ); 114bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta 115bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta return (struct task_struct *)tmp; 116bf90e1eab682dcb79b7765989fb65835ce9d6165Vineet Gupta} 117