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-rw-r--r--arch/arc/kernel/ctx_sw_asm.S60
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
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+++ b/arch/arc/kernel/ctx_sw_asm.S
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+/* 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)