1 files changed, 63 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..7c1f365ef
--- /dev/null
+++ b/arch/arc/kernel/ctx_sw_asm.S
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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)