microblaze_mmu_v2: entry.S, entry.h

Signed-off-by: Michal Simek <monstr@monstr.eu>

2 files changed, 1151 insertions, 2 deletions

diff --git a/arch/microblaze/include/asm/entry.h b/arch/microblaze/include/asm/entry.h
index e4c3aef884d..61abbd23264 100644
--- a/arch/microblaze/include/asm/entry.h
+++ b/arch/microblaze/include/asm/entry.h
@@ -1,8 +1,8 @@
 /*
  * Definitions used by low-level trap handlers
  *
- * Copyright (C) 2008 Michal Simek
- * Copyright (C) 2007 - 2008 PetaLogix
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2007-2009 PetaLogix
  * Copyright (C) 2007 John Williams <john.williams@petalogix.com>
  *
  * This file is subject to the terms and conditions of the GNU General
@@ -31,7 +31,40 @@ DECLARE_PER_CPU(unsigned int, R11_SAVE); /* Temp variable for entry */
 DECLARE_PER_CPU(unsigned int, CURRENT_SAVE); /* Saved current pointer */
 # endif /* __ASSEMBLY__ */
 
+#ifndef CONFIG_MMU
+
 /* noMMU hasn't any space for args */
 # define STATE_SAVE_ARG_SPACE	(0)
 
+#else /* CONFIG_MMU */
+
+/* If true, system calls save and restore all registers (except result
+ * registers, of course).  If false, then `call clobbered' registers
+ * will not be preserved, on the theory that system calls are basically
+ * function calls anyway, and the caller should be able to deal with it.
+ * This is a security risk, of course, as `internal' values may leak out
+ * after a system call, but that certainly doesn't matter very much for
+ * a processor with no MMU protection!  For a protected-mode kernel, it
+ * would be faster to just zero those registers before returning.
+ *
+ * I can not rely on the glibc implementation. If you turn it off make
+ * sure that r11/r12 is saved in user-space. --KAA
+ *
+ * These are special variables using by the kernel trap/interrupt code
+ * to save registers in, at a time when there are no spare registers we
+ * can use to do so, and we can't depend on the value of the stack
+ * pointer.  This means that they must be within a signed 16-bit
+ * displacement of 0x00000000.
+ */
+
+/* A `state save frame' is a struct pt_regs preceded by some extra space
+ * suitable for a function call stack frame. */
+
+/* Amount of room on the stack reserved for arguments and to satisfy the
+ * C calling conventions, in addition to the space used by the struct
+ * pt_regs that actually holds saved values. */
+#define STATE_SAVE_ARG_SPACE	(6*4) /* Up to six arguments */
+
+#endif /* CONFIG_MMU */
+
 #endif /* _ASM_MICROBLAZE_ENTRY_H */
diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
new file mode 100644
index 00000000000..91a0e7b185d
--- /dev/null
+++ b/arch/microblaze/kernel/entry.S
@@ -0,0 +1,1116 @@
+/*
+ * Low-level system-call handling, trap handlers and context-switching
+ *
+ * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
+ * Copyright (C) 2008-2009 PetaLogix
+ * Copyright (C) 2003		John Williams <jwilliams@itee.uq.edu.au>
+ * Copyright (C) 2001,2002	NEC Corporation
+ * Copyright (C) 2001,2002	Miles Bader <miles@gnu.org>
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file COPYING in the main directory of this
+ * archive for more details.
+ *
+ * Written by Miles Bader <miles@gnu.org>
+ * Heavily modified by John Williams for Microblaze
+ */
+
+#include <linux/sys.h>
+#include <linux/linkage.h>
+
+#include <asm/entry.h>
+#include <asm/current.h>
+#include <asm/processor.h>
+#include <asm/exceptions.h>
+#include <asm/asm-offsets.h>
+#include <asm/thread_info.h>
+
+#include <asm/page.h>
+#include <asm/unistd.h>
+
+#include <linux/errno.h>
+#include <asm/signal.h>
+
+/* The size of a state save frame. */
+#define STATE_SAVE_SIZE		(PT_SIZE + STATE_SAVE_ARG_SPACE)
+
+/* The offset of the struct pt_regs in a `state save frame' on the stack. */
+#define PTO	STATE_SAVE_ARG_SPACE /* 24 the space for args */
+
+#define C_ENTRY(name)	.globl name; .align 4; name
+
+/*
+ * Various ways of setting and clearing BIP in flags reg.
+ * This is mucky, but necessary using microblaze version that
+ * allows msr ops to write to BIP
+ */
+#if CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR
+	.macro	clear_bip
+	msrclr	r11, MSR_BIP
+	nop
+	.endm
+
+	.macro	set_bip
+	msrset	r11, MSR_BIP
+	nop
+	.endm
+
+	.macro	clear_eip
+	msrclr	r11, MSR_EIP
+	nop
+	.endm
+
+	.macro	set_ee
+	msrset	r11, MSR_EE
+	nop
+	.endm
+
+	.macro	disable_irq
+	msrclr	r11, MSR_IE
+	nop
+	.endm
+
+	.macro	enable_irq
+	msrset	r11, MSR_IE
+	nop
+	.endm
+
+	.macro	set_ums
+	msrset	r11, MSR_UMS
+	nop
+	msrclr	r11, MSR_VMS
+	nop
+	.endm
+
+	.macro	set_vms
+	msrclr	r11, MSR_UMS
+	nop
+	msrset	r11, MSR_VMS
+	nop
+	.endm
+
+	.macro	clear_vms_ums
+	msrclr	r11, MSR_VMS
+	nop
+	msrclr	r11, MSR_UMS
+	nop
+	.endm
+#else
+	.macro	clear_bip
+	mfs	r11, rmsr
+	nop
+	andi	r11, r11, ~MSR_BIP
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	set_bip
+	mfs	r11, rmsr
+	nop
+	ori	r11, r11, MSR_BIP
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	clear_eip
+	mfs	r11, rmsr
+	nop
+	andi	r11, r11, ~MSR_EIP
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	set_ee
+	mfs	r11, rmsr
+	nop
+	ori	r11, r11, MSR_EE
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	disable_irq
+	mfs	r11, rmsr
+	nop
+	andi	r11, r11, ~MSR_IE
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	enable_irq
+	mfs	r11, rmsr
+	nop
+	ori	r11, r11, MSR_IE
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro set_ums
+	mfs	r11, rmsr
+	nop
+	ori	r11, r11, MSR_VMS
+	andni	r11, r11, MSR_UMS
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	set_vms
+	mfs	r11, rmsr
+	nop
+	ori	r11, r11, MSR_VMS
+	andni	r11, r11, MSR_UMS
+	mts	rmsr, r11
+	nop
+	.endm
+
+	.macro	clear_vms_ums
+	mfs	r11, rmsr
+	nop
+	andni	r11, r11, (MSR_VMS|MSR_UMS)
+	mts	rmsr,r11
+	nop
+	.endm
+#endif
+
+/* Define how to call high-level functions. With MMU, virtual mode must be
+ * enabled when calling the high-level function. Clobbers R11.
+ * VM_ON, VM_OFF, DO_JUMP_BIPCLR, DO_CALL
+ */
+
+/* turn on virtual protected mode save */
+#define VM_ON		\
+	set_ums;		\
+	rted	r0, 2f;	\
+2: nop;
+
+/* turn off virtual protected mode save and user mode save*/
+#define VM_OFF			\
+	clear_vms_ums;			\
+	rted	r0, TOPHYS(1f);	\
+1: nop;
+
+#define SAVE_REGS \
+	swi	r2, r1, PTO+PT_R2;	/* Save SDA */			\
+	swi	r5, r1, PTO+PT_R5;					\
+	swi	r6, r1, PTO+PT_R6;					\
+	swi	r7, r1, PTO+PT_R7;					\
+	swi	r8, r1, PTO+PT_R8;					\
+	swi	r9, r1, PTO+PT_R9;					\
+	swi	r10, r1, PTO+PT_R10;					\
+	swi	r11, r1, PTO+PT_R11;	/* save clobbered regs after rval */\
+	swi	r12, r1, PTO+PT_R12;					\
+	swi	r13, r1, PTO+PT_R13;	/* Save SDA2 */			\
+	swi	r14, r1, PTO+PT_PC;	/* PC, before IRQ/trap */	\
+	swi	r15, r1, PTO+PT_R15;	/* Save LP */			\
+	swi	r18, r1, PTO+PT_R18;	/* Save asm scratch reg */	\
+	swi	r19, r1, PTO+PT_R19;					\
+	swi	r20, r1, PTO+PT_R20;					\
+	swi	r21, r1, PTO+PT_R21;					\
+	swi	r22, r1, PTO+PT_R22;					\
+	swi	r23, r1, PTO+PT_R23;					\
+	swi	r24, r1, PTO+PT_R24;					\
+	swi	r25, r1, PTO+PT_R25;					\
+	swi	r26, r1, PTO+PT_R26;					\
+	swi	r27, r1, PTO+PT_R27;					\
+	swi	r28, r1, PTO+PT_R28;					\
+	swi	r29, r1, PTO+PT_R29;					\
+	swi	r30, r1, PTO+PT_R30;					\
+	swi	r31, r1, PTO+PT_R31;	/* Save current task reg */	\
+	mfs	r11, rmsr;		/* save MSR */			\
+	nop;								\
+	swi	r11, r1, PTO+PT_MSR;
+
+#define RESTORE_REGS \
+	lwi	r11, r1, PTO+PT_MSR;					\
+	mts	rmsr , r11;						\
+	nop;								\
+	lwi	r2, r1, PTO+PT_R2;	/* restore SDA */		\
+	lwi	r5, r1, PTO+PT_R5;					\
+	lwi	r6, r1, PTO+PT_R6;					\
+	lwi	r7, r1, PTO+PT_R7;					\
+	lwi	r8, r1, PTO+PT_R8;					\
+	lwi	r9, r1, PTO+PT_R9;					\
+	lwi	r10, r1, PTO+PT_R10;					\
+	lwi	r11, r1, PTO+PT_R11;	/* restore clobbered regs after rval */\
+	lwi	r12, r1, PTO+PT_R12;					\
+	lwi	r13, r1, PTO+PT_R13;	/* restore SDA2 */		\
+	lwi	r14, r1, PTO+PT_PC;	/* RESTORE_LINK PC, before IRQ/trap */\
+	lwi	r15, r1, PTO+PT_R15;	/* restore LP */		\
+	lwi	r18, r1, PTO+PT_R18;	/* restore asm scratch reg */	\
+	lwi	r19, r1, PTO+PT_R19;					\
+	lwi	r20, r1, PTO+PT_R20;					\
+	lwi	r21, r1, PTO+PT_R21;					\
+	lwi	r22, r1, PTO+PT_R22;					\
+	lwi	r23, r1, PTO+PT_R23;					\
+	lwi	r24, r1, PTO+PT_R24;					\
+	lwi	r25, r1, PTO+PT_R25;					\
+	lwi	r26, r1, PTO+PT_R26;					\
+	lwi	r27, r1, PTO+PT_R27;					\
+	lwi	r28, r1, PTO+PT_R28;					\
+	lwi	r29, r1, PTO+PT_R29;					\
+	lwi	r30, r1, PTO+PT_R30;					\
+	lwi	r31, r1, PTO+PT_R31;	/* Restore cur task reg */
+
+.text
+
+/*
+ * User trap.
+ *
+ * System calls are handled here.
+ *
+ * Syscall protocol:
+ * Syscall number in r12, args in r5-r10
+ * Return value in r3
+ *
+ * Trap entered via brki instruction, so BIP bit is set, and interrupts
+ * are masked. This is nice, means we don't have to CLI before state save
+ */
+C_ENTRY(_user_exception):
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
+	addi	r14, r14, 4	/* return address is 4 byte after call */
+	swi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11);	/* Save r11 */
+
+	lwi	r11, r0, TOPHYS(PER_CPU(KM));/* See if already in kernel mode.*/
+	beqi	r11, 1f;		/* Jump ahead if coming from user */
+/* Kernel-mode state save. */
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
+	tophys(r1,r11);
+	swi	r11, r1, (PT_R1-PT_SIZE); /* Save original SP. */
+	lwi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* restore r11 */
+
+	addik	r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack. */
+	SAVE_REGS
+
+	addi	r11, r0, 1; 		/* Was in kernel-mode. */
+	swi	r11, r1, PTO+PT_MODE; /* pt_regs -> kernel mode */
+	brid	2f;
+	nop;				/* Fill delay slot */
+
+/* User-mode state save.  */
+1:
+	lwi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11);	/* restore r11 */
+	lwi	r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
+	tophys(r1,r1);
+	lwi	r1, r1, TS_THREAD_INFO;	/* get stack from task_struct */
+/* calculate kernel stack pointer from task struct 8k */
+	addik	r1, r1, THREAD_SIZE;
+	tophys(r1,r1);
+
+	addik	r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack.  */
+	SAVE_REGS
+
+	swi	r0, r1, PTO+PT_MODE;			/* Was in user-mode. */
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	swi	r11, r1, PTO+PT_R1;		/* Store user SP.  */
+	addi	r11, r0, 1;
+	swi	r11, r0, TOPHYS(PER_CPU(KM));	/* Now we're in kernel-mode.  */
+2:	lwi	r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE));	/* get saved current */
+	/* Save away the syscall number.  */
+	swi	r12, r1, PTO+PT_R0;
+	tovirt(r1,r1)
+
+	la	r15, r0, ret_from_trap-8
+/* where the trap should return need -8 to adjust for rtsd r15, 8*/
+/* Jump to the appropriate function for the system call number in r12
+ * (r12 is not preserved), or return an error if r12 is not valid. The LP
+ * register should point to the location where
+ * the called function should return.  [note that MAKE_SYS_CALL uses label 1] */
+	/* See if the system call number is valid.  */
+	addi	r11, r12, -__NR_syscalls;
+	bgei	r11,1f;
+	/* Figure out which function to use for this system call.  */
+	/* Note Microblaze barrel shift is optional, so don't rely on it */
+	add	r12, r12, r12;			/* convert num -> ptr */
+	add	r12, r12, r12;
+
+	/* Trac syscalls and stored them to r0_ram */
+	lwi	r3, r12, 0x400 + TOPHYS(r0_ram)
+	addi	r3, r3, 1
+	swi	r3, r12, 0x400 + TOPHYS(r0_ram)
+
+	lwi	r12, r12, TOPHYS(sys_call_table); /* Function ptr */
+	/* Make the system call.  to r12*/
+	set_vms;
+	rtid	r12, 0;
+	nop;
+	/* The syscall number is invalid, return an error.  */
+1:	VM_ON;	/* RETURN() expects virtual mode*/
+	addi	r3, r0, -ENOSYS;
+	rtsd	r15,8;		/* looks like a normal subroutine return */
+	or 	r0, r0, r0
+
+
+/* Entry point used to return from a syscall/trap.  */
+/* We re-enable BIP bit before state restore */
+C_ENTRY(ret_from_trap):
+	set_bip;			/*  Ints masked for state restore*/
+	lwi	r11, r1, PTO+PT_MODE;
+/* See if returning to kernel mode, if so, skip resched &c.  */
+	bnei	r11, 2f;
+
+	/* We're returning to user mode, so check for various conditions that
+	 * trigger rescheduling. */
+	/* Get current task ptr into r11 */
+	add	r11, r0, CURRENT_TASK;	/* Get current task ptr into r11 */
+	lwi	r11, r11, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;		/* get flags in thread info */
+	andi	r11, r11, _TIF_NEED_RESCHED;
+	beqi	r11, 5f;
+
+	swi	r3, r1, PTO + PT_R3; /* store syscall result */
+	swi	r4, r1, PTO + PT_R4;
+	bralid	r15, schedule;	/* Call scheduler */
+	nop;				/* delay slot */
+	lwi	r3, r1, PTO + PT_R3; /* restore syscall result */
+	lwi	r4, r1, PTO + PT_R4;
+
+	/* Maybe handle a signal */
+5:	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	lwi	r11, r11, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r11, _TIF_SIGPENDING;
+	beqi	r11, 1f;		/* Signals to handle, handle them */
+
+	swi	r3, r1, PTO + PT_R3; /* store syscall result */
+	swi	r4, r1, PTO + PT_R4;
+	la	r5, r1, PTO;		/* Arg 1: struct pt_regs *regs */
+	add	r6, r0, r0;		/* Arg 2: sigset_t *oldset */
+	addi	r7, r0, 1;		/* Arg 3: int in_syscall */
+	bralid	r15, do_signal;	/* Handle any signals */
+	nop;
+	lwi	r3, r1, PTO + PT_R3; /* restore syscall result */
+	lwi	r4, r1, PTO + PT_R4;
+
+/* Finally, return to user state.  */
+1:	swi	r0, r0, PER_CPU(KM);	/* Now officially in user state. */
+	add	r11, r0, CURRENT_TASK;	/* Get current task ptr into r11 */
+	swi	r11, r0, PER_CPU(CURRENT_SAVE); /* save current */
+	VM_OFF;
+	tophys(r1,r1);
+	RESTORE_REGS;
+	addik	r1, r1, STATE_SAVE_SIZE		/* Clean up stack space.  */
+	lwi	r1, r1, PT_R1 - PT_SIZE;/* Restore user stack pointer. */
+	bri	6f;
+
+/* Return to kernel state.  */
+2:	VM_OFF;
+	tophys(r1,r1);
+	RESTORE_REGS;
+	addik	r1, r1, STATE_SAVE_SIZE		/* Clean up stack space.  */
+	tovirt(r1,r1);
+6:
+TRAP_return:		/* Make global symbol for debugging */
+	rtbd	r14, 0;	/* Instructions to return from an IRQ */
+	nop;
+
+
+/* These syscalls need access to the struct pt_regs on the stack, so we
+   implement them in assembly (they're basically all wrappers anyway).  */
+
+C_ENTRY(sys_fork_wrapper):
+	addi	r5, r0, SIGCHLD			/* Arg 0: flags */
+	lwi	r6, r1, PTO+PT_R1	/* Arg 1: child SP (use parent's) */
+	la	r7, r1, PTO			/* Arg 2: parent context */
+	add	r8. r0, r0			/* Arg 3: (unused) */
+	add	r9, r0, r0;			/* Arg 4: (unused) */
+	add	r10, r0, r0;			/* Arg 5: (unused) */
+	brid	do_fork		/* Do real work (tail-call) */
+	nop;
+
+/* This the initial entry point for a new child thread, with an appropriate
+   stack in place that makes it look the the child is in the middle of an
+   syscall.  This function is actually `returned to' from switch_thread
+   (copy_thread makes ret_from_fork the return address in each new thread's
+   saved context).  */
+C_ENTRY(ret_from_fork):
+	bralid	r15, schedule_tail; /* ...which is schedule_tail's arg */
+	add	r3, r5, r0;	/* switch_thread returns the prev task */
+				/* ( in the delay slot ) */
+	add	r3, r0, r0;	/* Child's fork call should return 0. */
+	brid	ret_from_trap;	/* Do normal trap return */
+	nop;
+
+C_ENTRY(sys_vfork_wrapper):
+	la	r5, r1, PTO
+	brid	sys_vfork	/* Do real work (tail-call) */
+	nop
+
+C_ENTRY(sys_clone_wrapper):
+	bnei	r6, 1f;			/* See if child SP arg (arg 1) is 0. */
+	lwi	r6, r1, PTO+PT_R1;	/* If so, use paret's stack ptr */
+1:	la	r7, r1, PTO;			/* Arg 2: parent context */
+	add	r8, r0, r0;			/* Arg 3: (unused) */
+	add	r9, r0, r0;			/* Arg 4: (unused) */
+	add	r10, r0, r0;			/* Arg 5: (unused) */
+	brid	do_fork		/* Do real work (tail-call) */
+	nop;
+
+C_ENTRY(sys_execve_wrapper):
+	la	r8, r1, PTO;		/* add user context as 4th arg */
+	brid	sys_execve;	/* Do real work (tail-call).*/
+	nop;
+
+C_ENTRY(sys_sigsuspend_wrapper):
+	swi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	swi	r4, r1, PTO+PT_R4;
+	la	r6, r1, PTO;		/* add user context as 2nd arg */
+	bralid	r15, sys_sigsuspend; /* Do real work.*/
+	nop;
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	bri ret_from_trap /* fall through will not work here due to align */
+	nop;
+
+C_ENTRY(sys_rt_sigsuspend_wrapper):
+	swi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	swi	r4, r1, PTO+PT_R4;
+	la	r7, r1, PTO;		/* add user context as 3rd arg */
+	brlid	r15, sys_rt_sigsuspend;	/* Do real work.*/
+	nop;
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	bri ret_from_trap /* fall through will not work here due to align */
+	nop;
+
+
+C_ENTRY(sys_sigreturn_wrapper):
+	swi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	swi	r4, r1, PTO+PT_R4;
+	la	r5, r1, PTO;		/* add user context as 1st arg */
+	brlid	r15, sys_sigreturn;	/* Do real work.*/
+	nop;
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	bri ret_from_trap /* fall through will not work here due to align */
+	nop;
+
+C_ENTRY(sys_rt_sigreturn_wrapper):
+	swi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	swi	r4, r1, PTO+PT_R4;
+	la	r5, r1, PTO;		/* add user context as 1st arg */
+	brlid	r15, sys_rt_sigreturn	/* Do real work */
+	nop;
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	bri ret_from_trap /* fall through will not work here due to align */
+	nop;
+
+/*
+ * HW EXCEPTION rutine start
+ */
+
+#define SAVE_STATE	\
+	swi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* Save r11 */	\
+	set_bip;	/*equalize initial state for all possible entries*/\
+	clear_eip;							\
+	enable_irq;							\
+	set_ee;								\
+	/* See if already in kernel mode.*/				\
+	lwi	r11, r0, TOPHYS(PER_CPU(KM));				\
+	beqi	r11, 1f;		/* Jump ahead if coming from user */\
+	/* Kernel-mode state save.  */					\
+	/* Reload kernel stack-ptr. */					\
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));			\
+	tophys(r1,r11);							\
+	swi	r11, r1, (PT_R1-PT_SIZE); /* Save original SP. */	\
+	lwi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* restore r11 */\
+	addik	r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack.  */\
+	/* store return registers separately because			\
+	 * this macros is use for others exceptions */			\
+	swi	r3, r1, PTO + PT_R3;					\
+	swi	r4, r1, PTO + PT_R4;					\
+	SAVE_REGS							\
+	/* PC, before IRQ/trap - this is one instruction above */	\
+	swi	r17, r1, PTO+PT_PC;					\
+									\
+	addi	r11, r0, 1; 		/* Was in kernel-mode.  */	\
+	swi	r11, r1, PTO+PT_MODE; 	 				\
+	brid	2f;							\
+	nop;				/* Fill delay slot */		\
+1:	/* User-mode state save.  */					\
+	lwi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* restore r11 */\
+	lwi	r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */\
+	tophys(r1,r1);							\
+	lwi	r1, r1, TS_THREAD_INFO;	/* get the thread info */	\
+	addik	r1, r1, THREAD_SIZE;	/* calculate kernel stack pointer */\
+	tophys(r1,r1);							\
+									\
+	addik	r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack.  */\
+	/* store return registers separately because this macros	\
+	 * is use for others exceptions */				\
+	swi	r3, r1, PTO + PT_R3; 					\
+	swi	r4, r1, PTO + PT_R4;					\
+	SAVE_REGS							\
+	/* PC, before IRQ/trap - this is one instruction above FIXME*/	\
+	swi	r17, r1, PTO+PT_PC;					\
+									\
+	swi	r0, r1, PTO+PT_MODE; /* Was in user-mode.  */		\
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));			\
+	swi	r11, r1, PTO+PT_R1; /* Store user SP.  */		\
+	addi	r11, r0, 1;						\
+	swi	r11, r0, TOPHYS(PER_CPU(KM)); /* Now we're in kernel-mode.*/\
+2:	lwi	r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */\
+	/* Save away the syscall number.  */				\
+	swi	r0, r1, PTO+PT_R0;					\
+	tovirt(r1,r1)
+
+C_ENTRY(full_exception_trap):
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
+	/* adjust exception address for privileged instruction
+	 * for finding where is it */
+	addik	r17, r17, -4
+	SAVE_STATE /* Save registers */
+	/* FIXME this can be store directly in PT_ESR reg.
+	 * I tested it but there is a fault */
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	la	r15, r0, ret_from_exc - 8
+	la	r5, r1, PTO		 /* parameter struct pt_regs * regs */
+	mfs	r6, resr
+	nop
+	mfs	r7, rfsr;		/* save FSR */
+	nop
+	la	r12, r0, full_exception
+	set_vms;
+	rtbd	r12, 0;
+	nop;
+
+/*
+ * Unaligned data trap.
+ *
+ * Unaligned data trap last on 4k page is handled here.
+ *
+ * Trap entered via exception, so EE bit is set, and interrupts
+ * are masked.  This is nice, means we don't have to CLI before state save
+ *
+ * The assembler routine is in "arch/microblaze/kernel/hw_exception_handler.S"
+ */
+C_ENTRY(unaligned_data_trap):
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
+	SAVE_STATE		/* Save registers.*/
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	la	r15, r0, ret_from_exc-8
+	mfs	r3, resr		/* ESR */
+	nop
+	mfs	r4, rear		/* EAR */
+	nop
+	la	r7, r1, PTO		/* parameter struct pt_regs * regs */
+	la	r12, r0, _unaligned_data_exception
+	set_vms;
+	rtbd	r12, 0;	/* interrupts enabled */
+	nop;
+
+/*
+ * Page fault traps.
+ *
+ * If the real exception handler (from hw_exception_handler.S) didn't find
+ * the mapping for the process, then we're thrown here to handle such situation.
+ *
+ * Trap entered via exceptions, so EE bit is set, and interrupts
+ * are masked.  This is nice, means we don't have to CLI before state save
+ *
+ * Build a standard exception frame for TLB Access errors.  All TLB exceptions
+ * will bail out to this point if they can't resolve the lightweight TLB fault.
+ *
+ * The C function called is in "arch/microblaze/mm/fault.c", declared as:
+ * void do_page_fault(struct pt_regs *regs,
+ *				unsigned long address,
+ *				unsigned long error_code)
+ */
+/* data and intruction trap - which is choose is resolved int fault.c */
+C_ENTRY(page_fault_data_trap):
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
+	SAVE_STATE		/* Save registers.*/
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	la	r15, r0, ret_from_exc-8
+	la	r5, r1, PTO		/* parameter struct pt_regs * regs */
+	mfs	r6, rear		/* parameter unsigned long address */
+	nop
+	mfs	r7, resr		/* parameter unsigned long error_code */
+	nop
+	la	r12, r0, do_page_fault
+	set_vms;
+	rtbd	r12, 0;	/* interrupts enabled */
+	nop;
+
+C_ENTRY(page_fault_instr_trap):
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)) /* save stack */
+	SAVE_STATE		/* Save registers.*/
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	la	r15, r0, ret_from_exc-8
+	la	r5, r1, PTO		/* parameter struct pt_regs * regs */
+	mfs	r6, rear		/* parameter unsigned long address */
+	nop
+	ori	r7, r0, 0		/* parameter unsigned long error_code */
+	la	r12, r0, do_page_fault
+	set_vms;
+	rtbd	r12, 0;	/* interrupts enabled */
+	nop;
+
+/* Entry point used to return from an exception.  */
+C_ENTRY(ret_from_exc):
+	set_bip;			/*  Ints masked for state restore*/
+	lwi	r11, r1, PTO+PT_MODE;
+	bnei	r11, 2f;		/* See if returning to kernel mode, */
+					/* ... if so, skip resched &c.  */
+
+	/* We're returning to user mode, so check for various conditions that
+	   trigger rescheduling. */
+	/* Get current task ptr into r11 */
+	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	lwi	r11, r11, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r11, _TIF_NEED_RESCHED;
+	beqi	r11, 5f;
+
+/* Call the scheduler before returning from a syscall/trap. */
+	bralid	r15, schedule;	/* Call scheduler */
+	nop;				/* delay slot */
+
+	/* Maybe handle a signal */
+5:	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	lwi	r11, r11, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r11, _TIF_SIGPENDING;
+	beqi	r11, 1f;		/* Signals to handle, handle them */
+
+	/*
+	 * Handle a signal return; Pending signals should be in r18.
+	 *
+	 * Not all registers are saved by the normal trap/interrupt entry
+	 * points (for instance, call-saved registers (because the normal
+	 * C-compiler calling sequence in the kernel makes sure they're
+	 * preserved), and call-clobbered registers in the case of
+	 * traps), but signal handlers may want to examine or change the
+	 * complete register state.  Here we save anything not saved by
+	 * the normal entry sequence, so that it may be safely restored
+	 * (in a possibly modified form) after do_signal returns.
+	 * store return registers separately because this macros is use
+	 * for others exceptions */
+	swi	r3, r1, PTO + PT_R3;
+	swi	r4, r1, PTO + PT_R4;
+	la	r5, r1, PTO;		/* Arg 1: struct pt_regs *regs */
+	add	r6, r0, r0;		/* Arg 2: sigset_t *oldset */
+	addi	r7, r0, 0;		/* Arg 3: int in_syscall */
+	bralid	r15, do_signal;	/* Handle any signals */
+	nop;
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+
+/* Finally, return to user state.  */
+1:	swi	r0, r0, PER_CPU(KM);	/* Now officially in user state. */
+	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	swi	r11, r0, PER_CPU(CURRENT_SAVE); /* save current */
+	VM_OFF;
+	tophys(r1,r1);
+
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	RESTORE_REGS;
+	addik	r1, r1, STATE_SAVE_SIZE		/* Clean up stack space.  */
+
+	lwi	r1, r1, PT_R1 - PT_SIZE; /* Restore user stack pointer. */
+	bri	6f;
+/* Return to kernel state.  */
+2:	VM_OFF;
+	tophys(r1,r1);
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	RESTORE_REGS;
+	addik	r1, r1, STATE_SAVE_SIZE		/* Clean up stack space.  */
+
+	tovirt(r1,r1);
+6:
+EXC_return:		/* Make global symbol for debugging */
+	rtbd	r14, 0;	/* Instructions to return from an IRQ */
+	nop;
+
+/*
+ * HW EXCEPTION rutine end
+ */
+
+/*
+ * Hardware maskable interrupts.
+ *
+ * The stack-pointer (r1) should have already been saved to the memory
+ * location PER_CPU(ENTRY_SP).
+ */
+C_ENTRY(_interrupt):
+/* MS: we are in physical address */
+/* Save registers, switch to proper stack, convert SP to virtual.*/
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
+	swi	r11, r0, TOPHYS(PER_CPU(R11_SAVE));
+	/* MS: See if already in kernel mode. */
+	lwi	r11, r0, TOPHYS(PER_CPU(KM));
+	beqi	r11, 1f; /* MS: Jump ahead if coming from user */
+
+/* Kernel-mode state save. */
+	or	r11, r1, r0
+	tophys(r1,r11); /* MS: I have in r1 physical address where stack is */
+/* MS: Save original SP - position PT_R1 to next stack frame 4 *1 - 152*/
+	swi	r11, r1, (PT_R1 - PT_SIZE);
+/* MS: restore r11 because of saving in SAVE_REGS */
+	lwi	r11, r0, TOPHYS(PER_CPU(R11_SAVE));
+	/* save registers */
+/* MS: Make room on the stack -> activation record */
+	addik	r1, r1, -STATE_SAVE_SIZE;
+/* MS: store return registers separately because
+ * this macros is use for others exceptions */
+	swi	r3, r1, PTO + PT_R3;
+	swi	r4, r1, PTO + PT_R4;
+	SAVE_REGS
+	/* MS: store mode */
+	addi	r11, r0, 1; /* MS: Was in kernel-mode. */
+	swi	r11, r1, PTO + PT_MODE; /* MS: and save it */
+	brid	2f;
+	nop; /* MS: Fill delay slot */
+
+1:
+/* User-mode state save. */
+/* MS: restore r11 -> FIXME move before SAVE_REG */
+	lwi	r11, r0, TOPHYS(PER_CPU(R11_SAVE));
+ /* MS: get the saved current */
+	lwi	r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
+	tophys(r1,r1);
+	lwi	r1, r1, TS_THREAD_INFO;
+	addik	r1, r1, THREAD_SIZE;
+	tophys(r1,r1);
+	/* save registers */
+	addik	r1, r1, -STATE_SAVE_SIZE;
+	swi	r3, r1, PTO+PT_R3;
+	swi	r4, r1, PTO+PT_R4;
+	SAVE_REGS
+	/* calculate mode */
+	swi	r0, r1, PTO + PT_MODE;
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	swi	r11, r1, PTO+PT_R1;
+	/* setup kernel mode to KM */
+	addi	r11, r0, 1;
+	swi	r11, r0, TOPHYS(PER_CPU(KM));
+
+2:
+	lwi	r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
+	swi	r0, r1, PTO + PT_R0;
+	tovirt(r1,r1)
+	la	r5, r1, PTO;
+	set_vms;
+	la	r11, r0, do_IRQ;
+	la	r15, r0, irq_call;
+irq_call:rtbd	r11, 0;
+	nop;
+
+/* MS: we are in virtual mode */
+ret_from_irq:
+	lwi	r11, r1, PTO + PT_MODE;
+	bnei	r11, 2f;
+
+	add	r11, r0, CURRENT_TASK;
+	lwi	r11, r11, TS_THREAD_INFO;
+	lwi	r11, r11, TI_FLAGS; /* MS: get flags from thread info */
+	andi	r11, r11, _TIF_NEED_RESCHED;
+	beqi	r11, 5f
+	bralid	r15, schedule;
+	nop; /* delay slot */
+
+    /* Maybe handle a signal */
+5:	add	r11, r0, CURRENT_TASK;
+	lwi	r11, r11, TS_THREAD_INFO; /* MS: get thread info */
+	lwi	r11, r11, TI_FLAGS; /* get flags in thread info */
+	andi	r11, r11, _TIF_SIGPENDING;
+	beqid	r11, no_intr_resched
+/* Handle a signal return; Pending signals should be in r18. */
+	addi	r7, r0, 0; /* Arg 3: int in_syscall */
+	la	r5, r1, PTO; /* Arg 1: struct pt_regs *regs */
+	bralid	r15, do_signal;	/* Handle any signals */
+	add	r6, r0, r0; /* Arg 2: sigset_t *oldset */
+
+/* Finally, return to user state. */
+no_intr_resched:
+    /* Disable interrupts, we are now committed to the state restore */
+	disable_irq
+	swi	r0, r0, PER_CPU(KM); /* MS: Now officially in user state. */
+	add	r11, r0, CURRENT_TASK;
+	swi	r11, r0, PER_CPU(CURRENT_SAVE);
+	VM_OFF;
+	tophys(r1,r1);
+	lwi	r3, r1, PTO + PT_R3; /* MS: restore saved r3, r4 registers */
+	lwi	r4, r1, PTO + PT_R4;
+	RESTORE_REGS
+	addik	r1, r1, STATE_SAVE_SIZE /* MS: Clean up stack space. */
+	lwi	r1, r1, PT_R1 - PT_SIZE;
+	bri	6f;
+/* MS: Return to kernel state. */
+2:	VM_OFF /* MS: turn off MMU */
+	tophys(r1,r1)
+	lwi	r3, r1, PTO + PT_R3; /* MS: restore saved r3, r4 registers */
+	lwi	r4, r1, PTO + PT_R4;
+	RESTORE_REGS
+	addik	r1, r1, STATE_SAVE_SIZE	/* MS: Clean up stack space. */
+	tovirt(r1,r1);
+6:
+IRQ_return: /* MS: Make global symbol for debugging */
+	rtid	r14, 0
+	nop
+
+/*
+ * `Debug' trap
+ *  We enter dbtrap in "BIP" (breakpoint) mode.
+ *  So we exit the breakpoint mode with an 'rtbd' and proceed with the
+ *  original dbtrap.
+ *  however, wait to save state first
+ */
+C_ENTRY(_debug_exception):
+	/* BIP bit is set on entry, no interrupts can occur */
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
+
+	swi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* Save r11 */
+	set_bip;	/*equalize initial state for all possible entries*/
+	clear_eip;
+	enable_irq;
+	lwi	r11, r0, TOPHYS(PER_CPU(KM));/* See if already in kernel mode.*/
+	beqi	r11, 1f;		/* Jump ahead if coming from user */
+	/* Kernel-mode state save.  */
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
+	tophys(r1,r11);
+	swi	r11, r1, (PT_R1-PT_SIZE); /* Save original SP. */
+	lwi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* restore r11 */
+
+	addik	r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack.  */
+	swi	r3, r1, PTO + PT_R3;
+	swi	r4, r1, PTO + PT_R4;
+	SAVE_REGS;
+
+	addi	r11, r0, 1; 		/* Was in kernel-mode.  */
+	swi	r11, r1, PTO + PT_MODE;
+	brid	2f;
+	nop;				/* Fill delay slot */
+1:      /* User-mode state save.  */
+	lwi	r11, r0, TOPHYS(r0_ram + PTO + PT_R11); /* restore r11 */
+	lwi	r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
+	tophys(r1,r1);
+	lwi	r1, r1, TS_THREAD_INFO;	/* get the thread info */
+	addik	r1, r1, THREAD_SIZE;	/* calculate kernel stack pointer */
+	tophys(r1,r1);
+
+	addik	r1, r1, -STATE_SAVE_SIZE; /* Make room on the stack.  */
+	swi	r3, r1, PTO + PT_R3;
+	swi	r4, r1, PTO + PT_R4;
+	SAVE_REGS;
+
+	swi	r0, r1, PTO+PT_MODE; /* Was in user-mode.  */
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	swi	r11, r1, PTO+PT_R1; /* Store user SP.  */
+	addi	r11, r0, 1;
+	swi	r11, r0, TOPHYS(PER_CPU(KM));	/* Now we're in kernel-mode.  */
+2:	lwi	r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */
+	/* Save away the syscall number.  */
+	swi	r0, r1, PTO+PT_R0;
+	tovirt(r1,r1)
+
+	addi	r5, r0, SIGTRAP		     /* send the trap signal */
+	add	r6, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	addk	r7, r0, r0		     /* 3rd param zero */
+
+	set_vms;
+	la	r11, r0, send_sig;
+	la	r15, r0, dbtrap_call;
+dbtrap_call:	rtbd	r11, 0;
+	nop;
+
+	set_bip;			/*  Ints masked for state restore*/
+	lwi	r11, r1, PTO+PT_MODE;
+	bnei	r11, 2f;
+
+	/* Get current task ptr into r11 */
+	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	lwi	r11, r11, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r11, _TIF_NEED_RESCHED;
+	beqi	r11, 5f;
+
+/* Call the scheduler before returning from a syscall/trap. */
+
+	bralid	r15, schedule;	/* Call scheduler */
+	nop;				/* delay slot */
+	/* XXX Is PT_DTRACE handling needed here? */
+	/* XXX m68knommu also checks TASK_STATE & TASK_COUNTER here.  */
+
+	/* Maybe handle a signal */
+5:	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	lwi	r11, r11, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r11, _TIF_SIGPENDING;
+	beqi	r11, 1f;		/* Signals to handle, handle them */
+
+/* Handle a signal return; Pending signals should be in r18.  */
+	/* Not all registers are saved by the normal trap/interrupt entry
+	   points (for instance, call-saved registers (because the normal
+	   C-compiler calling sequence in the kernel makes sure they're
+	   preserved), and call-clobbered registers in the case of
+	   traps), but signal handlers may want to examine or change the
+	   complete register state.  Here we save anything not saved by
+	   the normal entry sequence, so that it may be safely restored
+	   (in a possibly modified form) after do_signal returns.  */
+
+	la	r5, r1, PTO;		/* Arg 1: struct pt_regs *regs */
+	add	r6, r0, r0;		/* Arg 2: sigset_t *oldset */
+	addi  r7, r0, 0;	/* Arg 3: int in_syscall */
+	bralid	r15, do_signal;	/* Handle any signals */
+	nop;
+
+
+/* Finally, return to user state.  */
+1:	swi	r0, r0, PER_CPU(KM);	/* Now officially in user state. */
+	add	r11, r0, CURRENT_TASK; /* Get current task ptr into r11 */
+	swi	r11, r0, PER_CPU(CURRENT_SAVE); /* save current */
+	VM_OFF;
+	tophys(r1,r1);
+
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	RESTORE_REGS
+	addik	r1, r1, STATE_SAVE_SIZE		/* Clean up stack space.  */
+
+
+	lwi	r1, r1, PT_R1 - PT_SIZE;
+					/* Restore user stack pointer. */
+	bri	6f;
+
+/* Return to kernel state.  */
+2:	VM_OFF;
+	tophys(r1,r1);
+	lwi	r3, r1, PTO+PT_R3; /* restore saved r3, r4 registers */
+	lwi	r4, r1, PTO+PT_R4;
+	RESTORE_REGS
+	addik	r1, r1, STATE_SAVE_SIZE		/* Clean up stack space.  */
+
+	tovirt(r1,r1);
+6:
+DBTRAP_return:		/* Make global symbol for debugging */
+	rtbd	r14, 0;	/* Instructions to return from an IRQ */
+	nop;
+
+
+
+ENTRY(_switch_to)
+	/* prepare return value */
+	addk	r3, r0, r31
+
+	/* save registers in cpu_context */
+	/* use r11 and r12, volatile registers, as temp register */
+	/* give start of cpu_context for previous process */
+	addik	r11, r5, TI_CPU_CONTEXT
+	swi	r1, r11, CC_R1
+	swi	r2, r11, CC_R2
+	/* skip volatile registers.
+	 * they are saved on stack when we jumped to _switch_to() */
+	/* dedicated registers */
+	swi	r13, r11, CC_R13
+	swi	r14, r11, CC_R14
+	swi	r15, r11, CC_R15
+	swi	r16, r11, CC_R16
+	swi	r17, r11, CC_R17
+	swi	r18, r11, CC_R18
+	/* save non-volatile registers */
+	swi	r19, r11, CC_R19
+	swi	r20, r11, CC_R20
+	swi	r21, r11, CC_R21
+	swi	r22, r11, CC_R22
+	swi	r23, r11, CC_R23
+	swi	r24, r11, CC_R24
+	swi	r25, r11, CC_R25
+	swi	r26, r11, CC_R26
+	swi	r27, r11, CC_R27
+	swi	r28, r11, CC_R28
+	swi	r29, r11, CC_R29
+	swi	r30, r11, CC_R30
+	/* special purpose registers */
+	mfs	r12, rmsr
+	nop
+	swi	r12, r11, CC_MSR
+	mfs	r12, rear
+	nop
+	swi	r12, r11, CC_EAR
+	mfs	r12, resr
+	nop
+	swi	r12, r11, CC_ESR
+	mfs	r12, rfsr
+	nop
+	swi	r12, r11, CC_FSR
+
+	/* update r31, the current */
+	lwi	r31, r6, TI_TASK/* give me pointer to task which will be next */
+	/* stored it to current_save too */
+	swi	r31, r0, PER_CPU(CURRENT_SAVE)
+
+	/* get new process' cpu context and restore */
+	/* give me start where start context of next task */
+	addik	r11, r6, TI_CPU_CONTEXT
+
+	/* non-volatile registers */
+	lwi	r30, r11, CC_R30
+	lwi	r29, r11, CC_R29
+	lwi	r28, r11, CC_R28
+	lwi	r27, r11, CC_R27
+	lwi	r26, r11, CC_R26
+	lwi	r25, r11, CC_R25
+	lwi	r24, r11, CC_R24
+	lwi	r23, r11, CC_R23
+	lwi	r22, r11, CC_R22
+	lwi	r21, r11, CC_R21
+	lwi	r20, r11, CC_R20
+	lwi	r19, r11, CC_R19
+	/* dedicated registers */
+	lwi	r18, r11, CC_R18
+	lwi	r17, r11, CC_R17
+	lwi	r16, r11, CC_R16
+	lwi	r15, r11, CC_R15
+	lwi	r14, r11, CC_R14
+	lwi	r13, r11, CC_R13
+	/* skip volatile registers */
+	lwi	r2, r11, CC_R2
+	lwi	r1, r11, CC_R1
+
+	/* special purpose registers */
+	lwi	r12, r11, CC_FSR
+	mts	rfsr, r12
+	nop
+	lwi	r12, r11, CC_MSR
+	mts	rmsr, r12
+	nop
+
+	rtsd	r15, 8
+	nop
+
+ENTRY(_reset)
+	brai	0x70; /* Jump back to FS-boot */
+
+ENTRY(_break)
+	mfs	r5, rmsr
+	nop
+	swi	r5, r0, 0x250 + TOPHYS(r0_ram)
+	mfs	r5, resr
+	nop
+	swi	r5, r0, 0x254 + TOPHYS(r0_ram)
+	bri	0
+
+	/* These are compiled and loaded into high memory, then
+	 * copied into place in mach_early_setup */
+	.section	.init.ivt, "ax"
+	.org	0x0
+	/* this is very important - here is the reset vector */
+	/* in current MMU branch you don't care what is here - it is
+	 * used from bootloader site - but this is correct for FS-BOOT */
+	brai	0x70
+	nop
+	brai	TOPHYS(_user_exception); /* syscall handler */
+	brai	TOPHYS(_interrupt);	/* Interrupt handler */
+	brai	TOPHYS(_break);		/* nmi trap handler */
+	brai	TOPHYS(_hw_exception_handler);	/* HW exception handler */
+
+	.org	0x60
+	brai	TOPHYS(_debug_exception);	/* debug trap handler*/
+
+.section .rodata,"a"
+#include "syscall_table.S"
+
+syscall_table_size=(.-sys_call_table)
+