Initial import

1 files changed, 1005 insertions, 0 deletions

diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
new file mode 100644
index 000000000..ef548510b
--- /dev/null
+++ b/arch/microblaze/kernel/entry.S
@@ -0,0 +1,1005 @@
+/*
+ * 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>
+
+#undef DEBUG
+
+#ifdef DEBUG
+/* Create space for syscalls counting. */
+.section .data
+.global syscall_debug_table
+.align 4
+syscall_debug_table:
+	.space	(__NR_syscalls * 4)
+#endif /* DEBUG */
+
+#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	r0, MSR_BIP
+	.endm
+
+	.macro	set_bip
+	msrset	r0, MSR_BIP
+	.endm
+
+	.macro	clear_eip
+	msrclr	r0, MSR_EIP
+	.endm
+
+	.macro	set_ee
+	msrset	r0, MSR_EE
+	.endm
+
+	.macro	disable_irq
+	msrclr	r0, MSR_IE
+	.endm
+
+	.macro	enable_irq
+	msrset	r0, MSR_IE
+	.endm
+
+	.macro	set_ums
+	msrset	r0, MSR_UMS
+	msrclr	r0, MSR_VMS
+	.endm
+
+	.macro	set_vms
+	msrclr	r0, MSR_UMS
+	msrset	r0, MSR_VMS
+	.endm
+
+	.macro	clear_ums
+	msrclr	r0, MSR_UMS
+	.endm
+
+	.macro	clear_vms_ums
+	msrclr	r0, MSR_VMS | MSR_UMS
+	.endm
+#else
+	.macro	clear_bip
+	mfs	r11, rmsr
+	andi	r11, r11, ~MSR_BIP
+	mts	rmsr, r11
+	.endm
+
+	.macro	set_bip
+	mfs	r11, rmsr
+	ori	r11, r11, MSR_BIP
+	mts	rmsr, r11
+	.endm
+
+	.macro	clear_eip
+	mfs	r11, rmsr
+	andi	r11, r11, ~MSR_EIP
+	mts	rmsr, r11
+	.endm
+
+	.macro	set_ee
+	mfs	r11, rmsr
+	ori	r11, r11, MSR_EE
+	mts	rmsr, r11
+	.endm
+
+	.macro	disable_irq
+	mfs	r11, rmsr
+	andi	r11, r11, ~MSR_IE
+	mts	rmsr, r11
+	.endm
+
+	.macro	enable_irq
+	mfs	r11, rmsr
+	ori	r11, r11, MSR_IE
+	mts	rmsr, r11
+	.endm
+
+	.macro set_ums
+	mfs	r11, rmsr
+	ori	r11, r11, MSR_VMS
+	andni	r11, r11, MSR_UMS
+	mts	rmsr, r11
+	.endm
+
+	.macro	set_vms
+	mfs	r11, rmsr
+	ori	r11, r11, MSR_VMS
+	andni	r11, r11, MSR_UMS
+	mts	rmsr, r11
+	.endm
+
+	.macro	clear_ums
+	mfs	r11, rmsr
+	andni	r11, r11, MSR_UMS
+	mts	rmsr,r11
+	.endm
+
+	.macro	clear_vms_ums
+	mfs	r11, rmsr
+	andni	r11, r11, (MSR_VMS|MSR_UMS)
+	mts	rmsr,r11
+	.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;	\
+	nop; \
+2:
+
+/* turn off virtual protected mode save and user mode save*/
+#define VM_OFF			\
+	clear_vms_ums;		\
+	rted	r0, TOPHYS(1f);	\
+	nop; \
+1:
+
+#define SAVE_REGS \
+	swi	r2, r1, PT_R2;	/* Save SDA */			\
+	swi	r3, r1, PT_R3;					\
+	swi	r4, r1, PT_R4;					\
+	swi	r5, r1, PT_R5;					\
+	swi	r6, r1, PT_R6;					\
+	swi	r7, r1, PT_R7;					\
+	swi	r8, r1, PT_R8;					\
+	swi	r9, r1, PT_R9;					\
+	swi	r10, r1, PT_R10;					\
+	swi	r11, r1, PT_R11;	/* save clobbered regs after rval */\
+	swi	r12, r1, PT_R12;					\
+	swi	r13, r1, PT_R13;	/* Save SDA2 */			\
+	swi	r14, r1, PT_PC;	/* PC, before IRQ/trap */	\
+	swi	r15, r1, PT_R15;	/* Save LP */			\
+	swi	r16, r1, PT_R16;					\
+	swi	r17, r1, PT_R17;					\
+	swi	r18, r1, PT_R18;	/* Save asm scratch reg */	\
+	swi	r19, r1, PT_R19;					\
+	swi	r20, r1, PT_R20;					\
+	swi	r21, r1, PT_R21;					\
+	swi	r22, r1, PT_R22;					\
+	swi	r23, r1, PT_R23;					\
+	swi	r24, r1, PT_R24;					\
+	swi	r25, r1, PT_R25;					\
+	swi	r26, r1, PT_R26;					\
+	swi	r27, r1, PT_R27;					\
+	swi	r28, r1, PT_R28;					\
+	swi	r29, r1, PT_R29;					\
+	swi	r30, r1, PT_R30;					\
+	swi	r31, r1, PT_R31;	/* Save current task reg */	\
+	mfs	r11, rmsr;		/* save MSR */			\
+	swi	r11, r1, PT_MSR;
+
+#define RESTORE_REGS \
+	lwi	r11, r1, PT_MSR;					\
+	mts	rmsr , r11;						\
+	lwi	r2, r1, PT_R2;	/* restore SDA */		\
+	lwi	r3, r1, PT_R3;					\
+	lwi	r4, r1, PT_R4;					\
+	lwi	r5, r1, PT_R5;					\
+	lwi	r6, r1, PT_R6;					\
+	lwi	r7, r1, PT_R7;					\
+	lwi	r8, r1, PT_R8;					\
+	lwi	r9, r1, PT_R9;					\
+	lwi	r10, r1, PT_R10;					\
+	lwi	r11, r1, PT_R11;	/* restore clobbered regs after rval */\
+	lwi	r12, r1, PT_R12;					\
+	lwi	r13, r1, PT_R13;	/* restore SDA2 */		\
+	lwi	r14, r1, PT_PC;	/* RESTORE_LINK PC, before IRQ/trap */\
+	lwi	r15, r1, PT_R15;	/* restore LP */		\
+	lwi	r16, r1, PT_R16;					\
+	lwi	r17, r1, PT_R17;					\
+	lwi	r18, r1, PT_R18;	/* restore asm scratch reg */	\
+	lwi	r19, r1, PT_R19;					\
+	lwi	r20, r1, PT_R20;					\
+	lwi	r21, r1, PT_R21;					\
+	lwi	r22, r1, PT_R22;					\
+	lwi	r23, r1, PT_R23;					\
+	lwi	r24, r1, PT_R24;					\
+	lwi	r25, r1, PT_R25;					\
+	lwi	r26, r1, PT_R26;					\
+	lwi	r27, r1, PT_R27;					\
+	lwi	r28, r1, PT_R28;					\
+	lwi	r29, r1, PT_R29;					\
+	lwi	r30, r1, PT_R30;					\
+	lwi	r31, r1, PT_R31;	/* Restore cur task reg */
+
+#define SAVE_STATE	\
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* save stack */	\
+	/* See if already in kernel mode.*/				\
+	mfs	r1, rmsr;						\
+	andi	r1, r1, MSR_UMS;					\
+	bnei	r1, 1f;						\
+	/* Kernel-mode state save.  */					\
+	/* Reload kernel stack-ptr. */					\
+	lwi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP));			\
+	/* FIXME: I can add these two lines to one */			\
+	/* tophys(r1,r1); */						\
+	/* addik	r1, r1, -PT_SIZE; */				\
+	addik	r1, r1, CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - PT_SIZE; \
+	SAVE_REGS							\
+	brid	2f;							\
+	swi	r1, r1, PT_MODE; 	 				\
+1:	/* User-mode state save.  */					\
+	lwi	r1, r0, TOPHYS(PER_CPU(CURRENT_SAVE)); /* get saved current */\
+	tophys(r1,r1);							\
+	lwi	r1, r1, TS_THREAD_INFO;	/* get the thread info */	\
+	/* MS these three instructions can be added to one */		\
+	/* addik	r1, r1, THREAD_SIZE; */				\
+	/* tophys(r1,r1); */						\
+	/* addik	r1, r1, -PT_SIZE; */			\
+	addik r1, r1, THREAD_SIZE + CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - PT_SIZE; \
+	SAVE_REGS							\
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));			\
+	swi	r11, r1, PT_R1; /* Store user SP.  */		\
+	swi	r0, r1, PT_MODE; /* Was in user-mode.  */		\
+	/* MS: I am clearing UMS even in case when I come from kernel space */ \
+	clear_ums; 							\
+2:	lwi	CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
+
+.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 */
+
+	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, -PT_SIZE; /* Make room on the stack.  */
+	SAVE_REGS
+	swi	r0, r1, PT_R3
+	swi	r0, r1, PT_R4
+
+	swi	r0, r1, PT_MODE;			/* Was in user-mode. */
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	swi	r11, r1, PT_R1;		/* Store user SP.  */
+	clear_ums;
+2:	lwi	CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
+	/* Save away the syscall number.  */
+	swi	r12, r1, PT_R0;
+	tovirt(r1,r1)
+
+/* 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] */
+
+	/* Step into virtual mode */
+	rtbd	r0, 3f
+	nop
+3:
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO /* get thread info */
+	lwi	r11, r11, TI_FLAGS	 /* get flags in thread info */
+	andi	r11, r11, _TIF_WORK_SYSCALL_MASK
+	beqi	r11, 4f
+
+	addik	r3, r0, -ENOSYS
+	swi	r3, r1, PT_R3
+	brlid	r15, do_syscall_trace_enter
+	addik	r5, r1, PT_R0
+
+	# do_syscall_trace_enter returns the new syscall nr.
+	addk	r12, r0, r3
+	lwi	r5, r1, PT_R5;
+	lwi	r6, r1, PT_R6;
+	lwi	r7, r1, PT_R7;
+	lwi	r8, r1, PT_R8;
+	lwi	r9, r1, PT_R9;
+	lwi	r10, r1, PT_R10;
+4:
+/* 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 */
+	blti	r12, 5f
+	addi	r11, r12, -__NR_syscalls;
+	bgei	r11, 5f;
+	/* 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;
+	addi	r30, r0, 1			/* restarts allowed */
+
+#ifdef DEBUG
+	/* Trac syscalls and stored them to syscall_debug_table */
+	/* The first syscall location stores total syscall number */
+	lwi	r3, r0, syscall_debug_table
+	addi	r3, r3, 1
+	swi	r3, r0, syscall_debug_table
+	lwi	r3, r12, syscall_debug_table
+	addi	r3, r3, 1
+	swi	r3, r12, syscall_debug_table
+#endif
+
+	# Find and jump into the syscall handler.
+	lwi	r12, r12, sys_call_table
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	addi	r15, r0, ret_from_trap-8
+	bra	r12
+
+	/* The syscall number is invalid, return an error.  */
+5:
+	braid	ret_from_trap
+	addi	r3, r0, -ENOSYS;
+
+/* Entry point used to return from a syscall/trap */
+/* We re-enable BIP bit before state restore */
+C_ENTRY(ret_from_trap):
+	swi	r3, r1, PT_R3
+	swi	r4, r1, PT_R4
+
+	lwi	r11, r1, 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. */
+	/* FIXME: Restructure all these flag checks. */
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;	/* get thread info */
+	lwi	r11, r11, TI_FLAGS;		/* get flags in thread info */
+	andi	r11, r11, _TIF_WORK_SYSCALL_MASK
+	beqi	r11, 1f
+
+	brlid	r15, do_syscall_trace_leave
+	addik	r5, r1, PT_R0
+1:
+	/* We're returning to user mode, so check for various conditions that
+	 * trigger rescheduling. */
+	/* get thread info from current task */
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;
+	lwi	r19, r11, TI_FLAGS;		/* get flags in thread info */
+	andi	r11, r19, _TIF_NEED_RESCHED;
+	beqi	r11, 5f;
+
+	bralid	r15, schedule;	/* Call scheduler */
+	nop;				/* delay slot */
+	bri	1b
+
+	/* Maybe handle a signal */
+5:
+	andi	r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
+	beqi	r11, 4f;		/* Signals to handle, handle them */
+
+	addik	r5, r1, 0;		/* Arg 1: struct pt_regs *regs */
+	bralid	r15, do_notify_resume;	/* Handle any signals */
+	add	r6, r30, r0;		/* Arg 2: int in_syscall */
+	add	r30, r0, r0		/* no more restarts */
+	bri	1b
+
+/* Finally, return to user state.  */
+4:	set_bip;			/*  Ints masked for state restore */
+	swi	CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
+	VM_OFF;
+	tophys(r1,r1);
+	RESTORE_REGS;
+	addik	r1, r1, PT_SIZE		/* Clean up stack space.  */
+	lwi	r1, r1, PT_R1 - PT_SIZE;/* Restore user stack pointer. */
+	bri	6f;
+
+/* Return to kernel state.  */
+2:	set_bip;			/*  Ints masked for state restore */
+	VM_OFF;
+	tophys(r1,r1);
+	RESTORE_REGS;
+	addik	r1, r1, PT_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;
+
+
+/* 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	r5, r3, r0;	/* switch_thread returns the prev task */
+				/* ( in the delay slot ) */
+	brid	ret_from_trap;	/* Do normal trap return */
+	add	r3, r0, r0;	/* Child's fork call should return 0. */
+
+C_ENTRY(ret_from_kernel_thread):
+	bralid	r15, schedule_tail; /* ...which is schedule_tail's arg */
+	add	r5, r3, r0;	/* switch_thread returns the prev task */
+				/* ( in the delay slot ) */
+	brald	r15, r20	/* fn was left in r20 */
+	addk	r5, r0, r19	/* ... and argument - in r19 */
+	brid	ret_from_trap
+	add	r3, r0, r0
+
+C_ENTRY(sys_rt_sigreturn_wrapper):
+	addik	r30, r0, 0		/* no restarts */
+	brid	sys_rt_sigreturn	/* Do real work */
+	addik	r5, r1, 0;		/* add user context as 1st arg */
+
+/*
+ * HW EXCEPTION rutine start
+ */
+C_ENTRY(full_exception_trap):
+	/* adjust exception address for privileged instruction
+	 * for finding where is it */
+	addik	r17, r17, -4
+	SAVE_STATE /* Save registers */
+	/* PC, before IRQ/trap - this is one instruction above */
+	swi	r17, r1, PT_PC;
+	tovirt(r1,r1)
+	/* 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 */
+	addik	r15, r0, ret_from_exc - 8
+	mfs	r6, resr
+	mfs	r7, rfsr;		/* save FSR */
+	mts	rfsr, r0;	/* Clear sticky fsr */
+	rted	r0, full_exception
+	addik	r5, r1, 0		 /* parameter struct pt_regs * regs */
+
+/*
+ * 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):
+	/* MS: I have to save r11 value and then restore it because
+	 * set_bit, clear_eip, set_ee use r11 as temp register if MSR
+	 * instructions are not used. We don't need to do if MSR instructions
+	 * are used and they use r0 instead of r11.
+	 * I am using ENTRY_SP which should be primary used only for stack
+	 * pointer saving. */
+	swi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	set_bip;        /* equalize initial state for all possible entries */
+	clear_eip;
+	set_ee;
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	SAVE_STATE		/* Save registers.*/
+	/* PC, before IRQ/trap - this is one instruction above */
+	swi	r17, r1, PT_PC;
+	tovirt(r1,r1)
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	addik	r15, r0, ret_from_exc-8
+	mfs	r3, resr		/* ESR */
+	mfs	r4, rear		/* EAR */
+	rtbd	r0, _unaligned_data_exception
+	addik	r7, r1, 0		/* parameter struct pt_regs * regs */
+
+/*
+ * 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):
+	SAVE_STATE		/* Save registers.*/
+	/* PC, before IRQ/trap - this is one instruction above */
+	swi	r17, r1, PT_PC;
+	tovirt(r1,r1)
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	addik	r15, r0, ret_from_exc-8
+	mfs	r6, rear		/* parameter unsigned long address */
+	mfs	r7, resr		/* parameter unsigned long error_code */
+	rted	r0, do_page_fault
+	addik	r5, r1, 0		/* parameter struct pt_regs * regs */
+
+C_ENTRY(page_fault_instr_trap):
+	SAVE_STATE		/* Save registers.*/
+	/* PC, before IRQ/trap - this is one instruction above */
+	swi	r17, r1, PT_PC;
+	tovirt(r1,r1)
+	/* where the trap should return need -8 to adjust for rtsd r15, 8 */
+	addik	r15, r0, ret_from_exc-8
+	mfs	r6, rear		/* parameter unsigned long address */
+	ori	r7, r0, 0		/* parameter unsigned long error_code */
+	rted	r0, do_page_fault
+	addik	r5, r1, 0		/* parameter struct pt_regs * regs */
+
+/* Entry point used to return from an exception.  */
+C_ENTRY(ret_from_exc):
+	lwi	r11, r1, 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. */
+1:
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;	/* get thread info */
+	lwi	r19, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r19, _TIF_NEED_RESCHED;
+	beqi	r11, 5f;
+
+/* Call the scheduler before returning from a syscall/trap. */
+	bralid	r15, schedule;	/* Call scheduler */
+	nop;				/* delay slot */
+	bri	1b
+
+	/* Maybe handle a signal */
+5:	andi	r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
+	beqi	r11, 4f;		/* 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_notify_resume returns. */
+	addik	r5, r1, 0;		/* Arg 1: struct pt_regs *regs */
+	bralid	r15, do_notify_resume;	/* Handle any signals */
+	addi	r6, r0, 0;		/* Arg 2: int in_syscall */
+	bri	1b
+
+/* Finally, return to user state.  */
+4:	set_bip;			/* Ints masked for state restore */
+	swi	CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
+	VM_OFF;
+	tophys(r1,r1);
+
+	RESTORE_REGS;
+	addik	r1, r1, PT_SIZE		/* Clean up stack space.  */
+
+	lwi	r1, r1, PT_R1 - PT_SIZE; /* Restore user stack pointer. */
+	bri	6f;
+/* Return to kernel state.  */
+2:	set_bip;			/* Ints masked for state restore */
+	VM_OFF;
+	tophys(r1,r1);
+	RESTORE_REGS;
+	addik	r1, r1, PT_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))
+	/* MS: See if already in kernel mode. */
+	mfs	r1, rmsr
+	nop
+	andi	r1, r1, MSR_UMS
+	bnei	r1, 1f
+
+/* Kernel-mode state save. */
+	lwi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
+	tophys(r1,r1); /* MS: I have in r1 physical address where stack is */
+	/* save registers */
+/* MS: Make room on the stack -> activation record */
+	addik	r1, r1, -PT_SIZE;
+	SAVE_REGS
+	brid	2f;
+	swi	r1, r1, PT_MODE; /* 0 - user mode, 1 - kernel mode */
+1:
+/* User-mode state 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, -PT_SIZE;
+	SAVE_REGS
+	/* calculate mode */
+	swi	r0, r1, PT_MODE;
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	swi	r11, r1, PT_R1;
+	clear_ums;
+2:
+	lwi	CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
+	tovirt(r1,r1)
+	addik	r15, r0, irq_call;
+irq_call:rtbd	r0, do_IRQ;
+	addik	r5, r1, 0;
+
+/* MS: we are in virtual mode */
+ret_from_irq:
+	lwi	r11, r1, PT_MODE;
+	bnei	r11, 2f;
+
+1:
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;
+	lwi	r19, r11, TI_FLAGS; /* MS: get flags from thread info */
+	andi	r11, r19, _TIF_NEED_RESCHED;
+	beqi	r11, 5f
+	bralid	r15, schedule;
+	nop; /* delay slot */
+	bri	1b
+
+    /* Maybe handle a signal */
+5:	andi	r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
+	beqid	r11, no_intr_resched
+/* Handle a signal return; Pending signals should be in r18. */
+	addik	r5, r1, 0; /* Arg 1: struct pt_regs *regs */
+	bralid	r15, do_notify_resume;	/* Handle any signals */
+	addi	r6, r0, 0; /* Arg 2: int in_syscall */
+	bri	1b
+
+/* Finally, return to user state. */
+no_intr_resched:
+    /* Disable interrupts, we are now committed to the state restore */
+	disable_irq
+	swi	CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE);
+	VM_OFF;
+	tophys(r1,r1);
+	RESTORE_REGS
+	addik	r1, r1, PT_SIZE /* MS: Clean up stack space. */
+	lwi	r1, r1, PT_R1 - PT_SIZE;
+	bri	6f;
+/* MS: Return to kernel state. */
+2:
+#ifdef CONFIG_PREEMPT
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;
+	/* MS: get preempt_count from thread info */
+	lwi	r5, r11, TI_PREEMPT_COUNT;
+	bgti	r5, restore;
+
+	lwi	r5, r11, TI_FLAGS;		/* get flags in thread info */
+	andi	r5, r5, _TIF_NEED_RESCHED;
+	beqi	r5, restore /* if zero jump over */
+
+preempt:
+	/* interrupts are off that's why I am calling preempt_chedule_irq */
+	bralid	r15, preempt_schedule_irq
+	nop
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;	/* get thread info */
+	lwi	r5, r11, TI_FLAGS;		/* get flags in thread info */
+	andi	r5, r5, _TIF_NEED_RESCHED;
+	bnei	r5, preempt /* if non zero jump to resched */
+restore:
+#endif
+	VM_OFF /* MS: turn off MMU */
+	tophys(r1,r1)
+	RESTORE_REGS
+	addik	r1, r1, PT_SIZE	/* MS: Clean up stack space. */
+	tovirt(r1,r1);
+6:
+IRQ_return: /* MS: Make global symbol for debugging */
+	rtid	r14, 0
+	nop
+
+/*
+ * Debug trap for KGDB. Enter to _debug_exception by brki r16, 0x18
+ * and call handling function with saved pt_regs
+ */
+C_ENTRY(_debug_exception):
+	/* BIP bit is set on entry, no interrupts can occur */
+	swi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP))
+
+	mfs	r1, rmsr
+	nop
+	andi	r1, r1, MSR_UMS
+	bnei	r1, 1f
+/* MS: Kernel-mode state save - kgdb */
+	lwi	r1, r0, TOPHYS(PER_CPU(ENTRY_SP)); /* Reload kernel stack-ptr*/
+
+	/* BIP bit is set on entry, no interrupts can occur */
+	addik   r1, r1, CONFIG_KERNEL_BASE_ADDR - CONFIG_KERNEL_START - PT_SIZE;
+	SAVE_REGS;
+	/* save all regs to pt_reg structure */
+	swi	r0, r1, PT_R0;	/* R0 must be saved too */
+	swi	r14, r1, PT_R14	/* rewrite saved R14 value */
+	swi	r16, r1, PT_PC; /* PC and r16 are the same */
+	/* save special purpose registers to pt_regs */
+	mfs	r11, rear;
+	swi	r11, r1, PT_EAR;
+	mfs	r11, resr;
+	swi	r11, r1, PT_ESR;
+	mfs	r11, rfsr;
+	swi	r11, r1, PT_FSR;
+
+	/* stack pointer is in physical address at it is decrease
+	 * by PT_SIZE but we need to get correct R1 value */
+	addik   r11, r1, CONFIG_KERNEL_START - CONFIG_KERNEL_BASE_ADDR + PT_SIZE;
+	swi	r11, r1, PT_R1
+	/* MS: r31 - current pointer isn't changed */
+	tovirt(r1,r1)
+#ifdef CONFIG_KGDB
+	addi	r5, r1, 0 /* pass pt_reg address as the first arg */
+	addik	r15, r0, dbtrap_call; /* return address */
+	rtbd	r0, microblaze_kgdb_break
+	nop;
+#endif
+	/* MS: Place handler for brki from kernel space if KGDB is OFF.
+	 * It is very unlikely that another brki instruction is called. */
+	bri 0
+
+/* MS: User-mode state save - gdb */
+1:	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, -PT_SIZE; /* Make room on the stack.  */
+	SAVE_REGS;
+	swi	r16, r1, PT_PC;	/* Save LP */
+	swi	r0, r1, PT_MODE; /* Was in user-mode.  */
+	lwi	r11, r0, TOPHYS(PER_CPU(ENTRY_SP));
+	swi	r11, r1, PT_R1; /* Store user SP.  */
+	lwi	CURRENT_TASK, r0, TOPHYS(PER_CPU(CURRENT_SAVE));
+	tovirt(r1,r1)
+	set_vms;
+	addik	r5, r1, 0;
+	addik	r15, r0, dbtrap_call;
+dbtrap_call: /* Return point for kernel/user entry + 8 because of rtsd r15, 8 */
+	rtbd	r0, sw_exception
+	nop
+
+	/* MS: The first instruction for the second part of the gdb/kgdb */
+	set_bip; /* Ints masked for state restore */
+	lwi	r11, r1, PT_MODE;
+	bnei	r11, 2f;
+/* MS: Return to user space - gdb */
+1:
+	/* Get current task ptr into r11 */
+	lwi	r11, CURRENT_TASK, TS_THREAD_INFO;	/* get thread info */
+	lwi	r19, r11, TI_FLAGS;	/* get flags in thread info */
+	andi	r11, r19, _TIF_NEED_RESCHED;
+	beqi	r11, 5f;
+
+	/* Call the scheduler before returning from a syscall/trap. */
+	bralid	r15, schedule;	/* Call scheduler */
+	nop;				/* delay slot */
+	bri	1b
+
+	/* Maybe handle a signal */
+5:	andi	r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME;
+	beqi	r11, 4f;		/* Signals to handle, handle them */
+
+	addik	r5, r1, 0;		/* Arg 1: struct pt_regs *regs */
+	bralid	r15, do_notify_resume;	/* Handle any signals */
+	addi  r6, r0, 0;	/* Arg 2: int in_syscall */
+	bri	1b
+
+/* Finally, return to user state.  */
+4:	swi	CURRENT_TASK, r0, PER_CPU(CURRENT_SAVE); /* save current */
+	VM_OFF;
+	tophys(r1,r1);
+	/* MS: Restore all regs */
+	RESTORE_REGS
+	addik	r1, r1, PT_SIZE	 /* Clean up stack space */
+	lwi	r1, r1, PT_R1 - PT_SIZE; /* Restore user stack pointer */
+DBTRAP_return_user: /* MS: Make global symbol for debugging */
+	rtbd	r16, 0; /* MS: Instructions to return from a debug trap */
+	nop;
+
+/* MS: Return to kernel state - kgdb */
+2:	VM_OFF;
+	tophys(r1,r1);
+	/* MS: Restore all regs */
+	RESTORE_REGS
+	lwi	r14, r1, PT_R14;
+	lwi	r16, r1, PT_PC;
+	addik	r1, r1, PT_SIZE; /* MS: Clean up stack space */
+	tovirt(r1,r1);
+DBTRAP_return_kernel: /* MS: Make global symbol for debugging */
+	rtbd	r16, 0; /* MS: Instructions to return from a debug trap */
+	nop;
+
+
+ENTRY(_switch_to)
+	/* prepare return value */
+	addk	r3, r0, CURRENT_TASK
+
+	/* 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
+	swi	r12, r11, CC_MSR
+	mfs	r12, rear
+	swi	r12, r11, CC_EAR
+	mfs	r12, resr
+	swi	r12, r11, CC_ESR
+	mfs	r12, rfsr
+	swi	r12, r11, CC_FSR
+
+	/* update r31, the current-give me pointer to task which will be next */
+	lwi	CURRENT_TASK, r6, TI_TASK
+	/* stored it to current_save too */
+	swi	CURRENT_TASK, 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
+	lwi	r12, r11, CC_MSR
+	mts	rmsr, r12
+
+	rtsd	r15, 8
+	nop
+
+ENTRY(_reset)
+	brai	0; /* Jump to reset vector */
+
+	/* These are compiled and loaded into high memory, then
+	 * copied into place in mach_early_setup */
+	.section	.init.ivt, "ax"
+#if CONFIG_MANUAL_RESET_VECTOR
+	.org	0x0
+	brai	CONFIG_MANUAL_RESET_VECTOR
+#endif
+	.org	0x8
+	brai	TOPHYS(_user_exception); /* syscall handler */
+	.org	0x10
+	brai	TOPHYS(_interrupt);	/* Interrupt handler */
+	.org	0x18
+	brai	TOPHYS(_debug_exception);	/* debug trap handler */
+	.org	0x20
+	brai	TOPHYS(_hw_exception_handler);	/* HW exception handler */
+
+.section .rodata,"a"
+#include "syscall_table.S"
+
+syscall_table_size=(.-sys_call_table)
+
+type_SYSCALL:
+	.ascii "SYSCALL\0"
+type_IRQ:
+	.ascii "IRQ\0"
+type_IRQ_PREEMPT:
+	.ascii "IRQ (PREEMPTED)\0"
+type_SYSCALL_PREEMPT:
+	.ascii " SYSCALL (PREEMPTED)\0"
+
+	/*
+	 * Trap decoding for stack unwinder
+	 * Tuples are (start addr, end addr, string)
+	 * If return address lies on [start addr, end addr],
+	 * unwinder displays 'string'
+	 */
+
+	.align 4
+.global microblaze_trap_handlers
+microblaze_trap_handlers:
+	/* Exact matches come first */
+	.word ret_from_trap; .word ret_from_trap   ; .word type_SYSCALL
+	.word ret_from_irq ; .word ret_from_irq    ; .word type_IRQ
+	/* Fuzzy matches go here */
+	.word ret_from_irq ; .word no_intr_resched ; .word type_IRQ_PREEMPT
+	.word ret_from_trap; .word TRAP_return     ; .word type_SYSCALL_PREEMPT
+	/* End of table */
+	.word 0               ; .word 0               ; .word 0