diff options
Diffstat (limited to 'arch/arc/kernel/ctx_sw_asm.S')
| -rw-r--r-- | arch/arc/kernel/ctx_sw_asm.S | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/arch/arc/kernel/ctx_sw_asm.S b/arch/arc/kernel/ctx_sw_asm.S new file mode 100644 index 000000000..02c461484 --- /dev/null +++ b/arch/arc/kernel/ctx_sw_asm.S @@ -0,0 +1,60 @@ +/* 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) |