#ifdef ARC_DW2_UNWIND_AS_CFI
-#define CFI_STARTPROC .cfi_startproc
-#define CFI_ENDPROC .cfi_endproc
-#define CFI_DEF_CFA .cfi_def_cfa
-#define CFI_REGISTER .cfi_register
-#define CFI_REL_OFFSET .cfi_rel_offset
-#define CFI_UNDEFINED .cfi_undefined
+#define CFI_STARTPROC .cfi_startproc
+#define CFI_ENDPROC .cfi_endproc
+#define CFI_DEF_CFA .cfi_def_cfa
+#define CFI_DEF_CFA_OFFSET .cfi_def_cfa_offset
+#define CFI_DEF_CFA_REGISTER .cfi_def_cfa_register
+#define CFI_OFFSET .cfi_offset
+#define CFI_REL_OFFSET .cfi_rel_offset
+#define CFI_REGISTER .cfi_register
+#define CFI_RESTORE .cfi_restore
+#define CFI_UNDEFINED .cfi_undefined
#else
#define CFI_IGNORE #
-#define CFI_STARTPROC CFI_IGNORE
-#define CFI_ENDPROC CFI_IGNORE
-#define CFI_DEF_CFA CFI_IGNORE
-#define CFI_REGISTER CFI_IGNORE
-#define CFI_REL_OFFSET CFI_IGNORE
-#define CFI_UNDEFINED CFI_IGNORE
+#define CFI_STARTPROC CFI_IGNORE
+#define CFI_ENDPROC CFI_IGNORE
+#define CFI_DEF_CFA CFI_IGNORE
+#define CFI_DEF_CFA_OFFSET CFI_IGNORE
+#define CFI_DEF_CFA_REGISTER CFI_IGNORE
+#define CFI_OFFSET CFI_IGNORE
+#define CFI_REL_OFFSET CFI_IGNORE
+#define CFI_REGISTER CFI_IGNORE
+#define CFI_RESTORE CFI_IGNORE
+#define CFI_UNDEFINED CFI_IGNORE
#endif /* !ARC_DW2_UNWIND_AS_CFI */
+++ /dev/null
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
- *
- * Vineetg: Aug 2009
- * -"C" version of lowest level context switch asm macro called by schedular
- * gcc doesn't generate the dward CFI info for hand written asm, hence can't
- * backtrace out of it (e.g. tasks sleeping in kernel).
- * So we cheat a bit by writing almost similar code in inline-asm.
- * -This is a hacky way of doing things, but there is no other simple way.
- * I don't want/intend to extend unwinding code to understand raw asm
- */
-
-#include <asm/asm-offsets.h>
-#include <asm/switch_to.h>
-#include <linux/sched/debug.h>
-
-#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4)
-
-struct task_struct *__sched
-__switch_to(struct task_struct *prev_task, struct task_struct *next_task)
-{
- unsigned int tmp;
- unsigned int prev = (unsigned int)prev_task;
- unsigned int next = (unsigned int)next_task;
-
- __asm__ __volatile__(
- /* FP/BLINK save generated by gcc (standard function prologue */
- "st.a r13, [sp, -4] \n\t"
- "st.a r14, [sp, -4] \n\t"
- "st.a r15, [sp, -4] \n\t"
- "st.a r16, [sp, -4] \n\t"
- "st.a r17, [sp, -4] \n\t"
- "st.a r18, [sp, -4] \n\t"
- "st.a r19, [sp, -4] \n\t"
- "st.a r20, [sp, -4] \n\t"
- "st.a r21, [sp, -4] \n\t"
- "st.a r22, [sp, -4] \n\t"
- "st.a r23, [sp, -4] \n\t"
- "st.a r24, [sp, -4] \n\t"
- "st.a r25, [sp, -4] \n\t"
-
- /* set ksp of outgoing task in tsk->thread.ksp */
-#if KSP_WORD_OFF <= 255
- "st.as sp, [%3, %1] \n\t"
-#else
- /*
- * Workaround for NR_CPUS=4k
- * %1 is bigger than 255 (S9 offset for st.as)
- */
- "add2 r24, %3, %1 \n\t"
- "st sp, [r24] \n\t"
-#endif
-
- /*
- * setup _current_task with incoming tsk.
- * optionally, set caching reg to that as well
- * For SMP extra work to get to &_current_task[cpu]
- * (open coded SET_CURR_TASK_ON_CPU)
- */
-#ifndef CONFIG_SMP
- "st %2, [@_current_task] \n\t"
-#else
- "lr r24, [identity] \n\t"
- "lsr r24, r24, 8 \n\t"
- "bmsk r24, r24, 7 \n\t"
- "add2 r24, @_current_task, r24 \n\t"
- "st %2, [r24] \n\t"
-#endif
-#ifdef CONFIG_ARC_CURR_IN_REG
- "mov gp, %2 \n\t"
-#endif
-
- /* get ksp of incoming task from tsk->thread.ksp */
- "ld.as sp, [%2, %1] \n\t"
-
- /* start loading it's CALLEE reg file */
- "ld.ab r25, [sp, 4] \n\t"
- "ld.ab r24, [sp, 4] \n\t"
- "ld.ab r23, [sp, 4] \n\t"
- "ld.ab r22, [sp, 4] \n\t"
- "ld.ab r21, [sp, 4] \n\t"
- "ld.ab r20, [sp, 4] \n\t"
- "ld.ab r19, [sp, 4] \n\t"
- "ld.ab r18, [sp, 4] \n\t"
- "ld.ab r17, [sp, 4] \n\t"
- "ld.ab r16, [sp, 4] \n\t"
- "ld.ab r15, [sp, 4] \n\t"
- "ld.ab r14, [sp, 4] \n\t"
- "ld.ab r13, [sp, 4] \n\t"
-
- /* last (ret value) = prev : although for ARC it mov r0, r0 */
- "mov %0, %3 \n\t"
-
- /* FP/BLINK restore generated by gcc (standard func epilogue */
-
- : "=r"(tmp)
- : "n"(KSP_WORD_OFF), "r"(next), "r"(prev)
- : "blink"
- );
-
- return (struct task_struct *)tmp;
-}
#define KSP_WORD_OFF ((TASK_THREAD + THREAD_KSP) / 4)
-;################### Low Level Context Switch ##########################
+; IN
+; - r0: prev task (also current)
+; - r1: next task
+; OUT
+; - r0: prev task (so r0 not touched)
.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]
+ENTRY_CFI(__switch_to)
+
+ /* save kernel stack frame regs of @prev task */
+ push blink
+ CFI_DEF_CFA_OFFSET 4
+ CFI_OFFSET r31, -4
+
+ push fp
+ CFI_DEF_CFA_OFFSET 8
+ CFI_OFFSET r27, -8
+
+ mov fp, sp
+ CFI_DEF_CFA_REGISTER r27
+
+ /* kernel mode callee regs of @prev */
SAVE_CALLEE_SAVED_KERNEL
- /* Save the now KSP in task->thread.ksp */
+ /* save final SP to @prev->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]
+ add2 r10, r0, KSP_WORD_OFF
+ st sp, [r10]
#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, KSP_WORD_OFF]
-
- /* restore the registers */
+ /* update @next in _current_task[] and GP register caching it */
+ SET_CURR_TASK_ON_CPU r1, r10
+
+ /* load SP from @next->thread.ksp */
+ ld.as sp, [r1, KSP_WORD_OFF]
+
+ /* restore callee regs, stack frame regs of @next */
RESTORE_CALLEE_SAVED_KERNEL
- ld.ab fp, [sp, 4]
- ld.ab blink, [sp, 4]
- j [blink]
+ pop fp
+ CFI_RESTORE r27
+ CFI_DEF_CFA r28, 4
+
+ pop blink
+ CFI_RESTORE r31
+ CFI_DEF_CFA_OFFSET 0
+
+ j [blink]
END_CFI(__switch_to)
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