| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* |
| * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) |
| * |
| * Vineetg: Aug 2009 |
| * -Moved core context switch macro out of entry.S into this file. |
| * -This is the more "natural" hand written assembler |
| */ |
| |
| #include <linux/linkage.h> |
| #include <asm/entry.h> /* For the SAVE_* macros */ |
| #include <asm/asm-offsets.h> |
| |
| #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: |
| CFI_STARTPROC |
| |
| /* 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 |
| */ |
| |
| /* |
| * 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_CFI(__switch_to) |
