Initial import

1 files changed, 982 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
new file mode 100644
index 000000000..7d7d86352
--- /dev/null
+++ b/arch/powerpc/kernel/head_40x.S
@@ -0,0 +1,982 @@
+/*
+ *    Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org>
+ *      Initial PowerPC version.
+ *    Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu>
+ *      Rewritten for PReP
+ *    Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au>
+ *      Low-level exception handers, MMU support, and rewrite.
+ *    Copyright (c) 1997 Dan Malek <dmalek@jlc.net>
+ *      PowerPC 8xx modifications.
+ *    Copyright (c) 1998-1999 TiVo, Inc.
+ *      PowerPC 403GCX modifications.
+ *    Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu>
+ *      PowerPC 403GCX/405GP modifications.
+ *    Copyright 2000 MontaVista Software Inc.
+ *	PPC405 modifications
+ *      PowerPC 403GCX/405GP modifications.
+ * 	Author: MontaVista Software, Inc.
+ *         	frank_rowand@mvista.com or source@mvista.com
+ * 	   	debbie_chu@mvista.com
+ *
+ *
+ *    Module name: head_4xx.S
+ *
+ *    Description:
+ *      Kernel execution entry point code.
+ *
+ *    This program is free software; you can redistribute it and/or
+ *    modify it under the terms of the GNU General Public License
+ *    as published by the Free Software Foundation; either version
+ *    2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/init.h>
+#include <asm/processor.h>
+#include <asm/page.h>
+#include <asm/mmu.h>
+#include <asm/pgtable.h>
+#include <asm/cputable.h>
+#include <asm/thread_info.h>
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/ptrace.h>
+
+/* As with the other PowerPC ports, it is expected that when code
+ * execution begins here, the following registers contain valid, yet
+ * optional, information:
+ *
+ *   r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.)
+ *   r4 - Starting address of the init RAM disk
+ *   r5 - Ending address of the init RAM disk
+ *   r6 - Start of kernel command line string (e.g. "mem=96m")
+ *   r7 - End of kernel command line string
+ *
+ * This is all going to change RSN when we add bi_recs.......  -- Dan
+ */
+	__HEAD
+_ENTRY(_stext);
+_ENTRY(_start);
+
+	mr	r31,r3			/* save device tree ptr */
+
+	/* We have to turn on the MMU right away so we get cache modes
+	 * set correctly.
+	 */
+	bl	initial_mmu
+
+/* We now have the lower 16 Meg mapped into TLB entries, and the caches
+ * ready to work.
+ */
+turn_on_mmu:
+	lis	r0,MSR_KERNEL@h
+	ori	r0,r0,MSR_KERNEL@l
+	mtspr	SPRN_SRR1,r0
+	lis	r0,start_here@h
+	ori	r0,r0,start_here@l
+	mtspr	SPRN_SRR0,r0
+	SYNC
+	rfi				/* enables MMU */
+	b	.			/* prevent prefetch past rfi */
+
+/*
+ * This area is used for temporarily saving registers during the
+ * critical exception prolog.
+ */
+	. = 0xc0
+crit_save:
+_ENTRY(crit_r10)
+	.space	4
+_ENTRY(crit_r11)
+	.space	4
+_ENTRY(crit_srr0)
+	.space	4
+_ENTRY(crit_srr1)
+	.space	4
+_ENTRY(saved_ksp_limit)
+	.space	4
+
+/*
+ * Exception vector entry code. This code runs with address translation
+ * turned off (i.e. using physical addresses). We assume SPRG_THREAD has
+ * the physical address of the current task thread_struct.
+ * Note that we have to have decremented r1 before we write to any fields
+ * of the exception frame, since a critical interrupt could occur at any
+ * time, and it will write to the area immediately below the current r1.
+ */
+#define NORMAL_EXCEPTION_PROLOG						     \
+	mtspr	SPRN_SPRG_SCRATCH0,r10;	/* save two registers to work with */\
+	mtspr	SPRN_SPRG_SCRATCH1,r11;					     \
+	mtspr	SPRN_SPRG_SCRATCH2,r1;					     \
+	mfcr	r10;			/* save CR in r10 for now	   */\
+	mfspr	r11,SPRN_SRR1;		/* check whether user or kernel    */\
+	andi.	r11,r11,MSR_PR;						     \
+	beq	1f;							     \
+	mfspr	r1,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
+	lwz	r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack   */\
+	addi	r1,r1,THREAD_SIZE;					     \
+1:	subi	r1,r1,INT_FRAME_SIZE;	/* Allocate an exception frame     */\
+	tophys(r11,r1);							     \
+	stw	r10,_CCR(r11);          /* save various registers	   */\
+	stw	r12,GPR12(r11);						     \
+	stw	r9,GPR9(r11);						     \
+	mfspr	r10,SPRN_SPRG_SCRATCH0;					     \
+	stw	r10,GPR10(r11);						     \
+	mfspr	r12,SPRN_SPRG_SCRATCH1;					     \
+	stw	r12,GPR11(r11);						     \
+	mflr	r10;							     \
+	stw	r10,_LINK(r11);						     \
+	mfspr	r10,SPRN_SPRG_SCRATCH2;					     \
+	mfspr	r12,SPRN_SRR0;						     \
+	stw	r10,GPR1(r11);						     \
+	mfspr	r9,SPRN_SRR1;						     \
+	stw	r10,0(r11);						     \
+	rlwinm	r9,r9,0,14,12;		/* clear MSR_WE (necessary?)	   */\
+	stw	r0,GPR0(r11);						     \
+	SAVE_4GPRS(3, r11);						     \
+	SAVE_2GPRS(7, r11)
+
+/*
+ * Exception prolog for critical exceptions.  This is a little different
+ * from the normal exception prolog above since a critical exception
+ * can potentially occur at any point during normal exception processing.
+ * Thus we cannot use the same SPRG registers as the normal prolog above.
+ * Instead we use a couple of words of memory at low physical addresses.
+ * This is OK since we don't support SMP on these processors.
+ */
+#define CRITICAL_EXCEPTION_PROLOG					     \
+	stw	r10,crit_r10@l(0);	/* save two registers to work with */\
+	stw	r11,crit_r11@l(0);					     \
+	mfcr	r10;			/* save CR in r10 for now	   */\
+	mfspr	r11,SPRN_SRR3;		/* check whether user or kernel    */\
+	andi.	r11,r11,MSR_PR;						     \
+	lis	r11,critirq_ctx@ha;					     \
+	tophys(r11,r11);						     \
+	lwz	r11,critirq_ctx@l(r11);					     \
+	beq	1f;							     \
+	/* COMING FROM USER MODE */					     \
+	mfspr	r11,SPRN_SPRG_THREAD;	/* if from user, start at top of   */\
+	lwz	r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
+1:	addi	r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm  */\
+	tophys(r11,r11);						     \
+	stw	r10,_CCR(r11);          /* save various registers	   */\
+	stw	r12,GPR12(r11);						     \
+	stw	r9,GPR9(r11);						     \
+	mflr	r10;							     \
+	stw	r10,_LINK(r11);						     \
+	mfspr	r12,SPRN_DEAR;		/* save DEAR and ESR in the frame  */\
+	stw	r12,_DEAR(r11);		/* since they may have had stuff   */\
+	mfspr	r9,SPRN_ESR;		/* in them at the point where the  */\
+	stw	r9,_ESR(r11);		/* exception was taken		   */\
+	mfspr	r12,SPRN_SRR2;						     \
+	stw	r1,GPR1(r11);						     \
+	mfspr	r9,SPRN_SRR3;						     \
+	stw	r1,0(r11);						     \
+	tovirt(r1,r11);							     \
+	rlwinm	r9,r9,0,14,12;		/* clear MSR_WE (necessary?)	   */\
+	stw	r0,GPR0(r11);						     \
+	SAVE_4GPRS(3, r11);						     \
+	SAVE_2GPRS(7, r11)
+
+	/*
+	 * State at this point:
+	 * r9 saved in stack frame, now saved SRR3 & ~MSR_WE
+	 * r10 saved in crit_r10 and in stack frame, trashed
+	 * r11 saved in crit_r11 and in stack frame,
+	 *	now phys stack/exception frame pointer
+	 * r12 saved in stack frame, now saved SRR2
+	 * CR saved in stack frame, CR0.EQ = !SRR3.PR
+	 * LR, DEAR, ESR in stack frame
+	 * r1 saved in stack frame, now virt stack/excframe pointer
+	 * r0, r3-r8 saved in stack frame
+	 */
+
+/*
+ * Exception vectors.
+ */
+#define	START_EXCEPTION(n, label)					     \
+	. = n;								     \
+label:
+
+#define EXCEPTION(n, label, hdlr, xfer)				\
+	START_EXCEPTION(n, label);				\
+	NORMAL_EXCEPTION_PROLOG;				\
+	addi	r3,r1,STACK_FRAME_OVERHEAD;			\
+	xfer(n, hdlr)
+
+#define CRITICAL_EXCEPTION(n, label, hdlr)			\
+	START_EXCEPTION(n, label);				\
+	CRITICAL_EXCEPTION_PROLOG;				\
+	addi	r3,r1,STACK_FRAME_OVERHEAD;			\
+	EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
+			  NOCOPY, crit_transfer_to_handler,	\
+			  ret_from_crit_exc)
+
+#define EXC_XFER_TEMPLATE(hdlr, trap, msr, copyee, tfer, ret)	\
+	li	r10,trap;					\
+	stw	r10,_TRAP(r11);					\
+	lis	r10,msr@h;					\
+	ori	r10,r10,msr@l;					\
+	copyee(r10, r9);					\
+	bl	tfer;		 				\
+	.long	hdlr;						\
+	.long	ret
+
+#define COPY_EE(d, s)		rlwimi d,s,0,16,16
+#define NOCOPY(d, s)
+
+#define EXC_XFER_STD(n, hdlr)		\
+	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, NOCOPY, transfer_to_handler_full, \
+			  ret_from_except_full)
+
+#define EXC_XFER_LITE(n, hdlr)		\
+	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
+			  ret_from_except)
+
+#define EXC_XFER_EE(n, hdlr)		\
+	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \
+			  ret_from_except_full)
+
+#define EXC_XFER_EE_LITE(n, hdlr)	\
+	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, COPY_EE, transfer_to_handler, \
+			  ret_from_except)
+
+
+/*
+ * 0x0100 - Critical Interrupt Exception
+ */
+	CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception)
+
+/*
+ * 0x0200 - Machine Check Exception
+ */
+	CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
+
+/*
+ * 0x0300 - Data Storage Exception
+ * This happens for just a few reasons.  U0 set (but we don't do that),
+ * or zone protection fault (user violation, write to protected page).
+ * If this is just an update of modified status, we do that quickly
+ * and exit.  Otherwise, we call heavywight functions to do the work.
+ */
+	START_EXCEPTION(0x0300,	DataStorage)
+	mtspr	SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
+	mtspr	SPRN_SPRG_SCRATCH1, r11
+#ifdef CONFIG_403GCX
+	stw     r12, 0(r0)
+	stw     r9, 4(r0)
+	mfcr    r11
+	mfspr   r12, SPRN_PID
+	stw     r11, 8(r0)
+	stw     r12, 12(r0)
+#else
+	mtspr	SPRN_SPRG_SCRATCH3, r12
+	mtspr	SPRN_SPRG_SCRATCH4, r9
+	mfcr	r11
+	mfspr	r12, SPRN_PID
+	mtspr	SPRN_SPRG_SCRATCH6, r11
+	mtspr	SPRN_SPRG_SCRATCH5, r12
+#endif
+
+	/* First, check if it was a zone fault (which means a user
+	* tried to access a kernel or read-protected page - always
+	* a SEGV).  All other faults here must be stores, so no
+	* need to check ESR_DST as well. */
+	mfspr	r10, SPRN_ESR
+	andis.	r10, r10, ESR_DIZ@h
+	bne	2f
+
+	mfspr	r10, SPRN_DEAR		/* Get faulting address */
+
+	/* If we are faulting a kernel address, we have to use the
+	 * kernel page tables.
+	 */
+	lis	r11, PAGE_OFFSET@h
+	cmplw	r10, r11
+	blt+	3f
+	lis	r11, swapper_pg_dir@h
+	ori	r11, r11, swapper_pg_dir@l
+	li	r9, 0
+	mtspr	SPRN_PID, r9		/* TLB will have 0 TID */
+	b	4f
+
+	/* Get the PGD for the current thread.
+	 */
+3:
+	mfspr	r11,SPRN_SPRG_THREAD
+	lwz	r11,PGDIR(r11)
+4:
+	tophys(r11, r11)
+	rlwimi	r11, r10, 12, 20, 29	/* Create L1 (pgdir/pmd) address */
+	lwz	r11, 0(r11)		/* Get L1 entry */
+	rlwinm.	r12, r11, 0, 0, 19	/* Extract L2 (pte) base address */
+	beq	2f			/* Bail if no table */
+
+	rlwimi	r12, r10, 22, 20, 29	/* Compute PTE address */
+	lwz	r11, 0(r12)		/* Get Linux PTE */
+
+	andi.	r9, r11, _PAGE_RW	/* Is it writeable? */
+	beq	2f			/* Bail if not */
+
+	/* Update 'changed'.
+	*/
+	ori	r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
+	stw	r11, 0(r12)		/* Update Linux page table */
+
+	/* Most of the Linux PTE is ready to load into the TLB LO.
+	 * We set ZSEL, where only the LS-bit determines user access.
+	 * We set execute, because we don't have the granularity to
+	 * properly set this at the page level (Linux problem).
+	 * If shared is set, we cause a zero PID->TID load.
+	 * Many of these bits are software only.  Bits we don't set
+	 * here we (properly should) assume have the appropriate value.
+	 */
+	li	r12, 0x0ce2
+	andc	r11, r11, r12		/* Make sure 20, 21 are zero */
+
+	/* find the TLB index that caused the fault.  It has to be here.
+	*/
+	tlbsx	r9, 0, r10
+
+	tlbwe	r11, r9, TLB_DATA		/* Load TLB LO */
+
+	/* Done...restore registers and get out of here.
+	*/
+#ifdef CONFIG_403GCX
+	lwz     r12, 12(r0)
+	lwz     r11, 8(r0)
+	mtspr   SPRN_PID, r12
+	mtcr    r11
+	lwz     r9, 4(r0)
+	lwz     r12, 0(r0)
+#else
+	mfspr	r12, SPRN_SPRG_SCRATCH5
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mtspr	SPRN_PID, r12
+	mtcr	r11
+	mfspr	r9, SPRN_SPRG_SCRATCH4
+	mfspr	r12, SPRN_SPRG_SCRATCH3
+#endif
+	mfspr	r11, SPRN_SPRG_SCRATCH1
+	mfspr	r10, SPRN_SPRG_SCRATCH0
+	PPC405_ERR77_SYNC
+	rfi			/* Should sync shadow TLBs */
+	b	.		/* prevent prefetch past rfi */
+
+2:
+	/* The bailout.  Restore registers to pre-exception conditions
+	 * and call the heavyweights to help us out.
+	 */
+#ifdef CONFIG_403GCX
+	lwz     r12, 12(r0)
+	lwz     r11, 8(r0)
+	mtspr   SPRN_PID, r12
+	mtcr    r11
+	lwz     r9, 4(r0)
+	lwz     r12, 0(r0)
+#else
+	mfspr	r12, SPRN_SPRG_SCRATCH5
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mtspr	SPRN_PID, r12
+	mtcr	r11
+	mfspr	r9, SPRN_SPRG_SCRATCH4
+	mfspr	r12, SPRN_SPRG_SCRATCH3
+#endif
+	mfspr	r11, SPRN_SPRG_SCRATCH1
+	mfspr	r10, SPRN_SPRG_SCRATCH0
+	b	DataAccess
+
+/*
+ * 0x0400 - Instruction Storage Exception
+ * This is caused by a fetch from non-execute or guarded pages.
+ */
+	START_EXCEPTION(0x0400, InstructionAccess)
+	NORMAL_EXCEPTION_PROLOG
+	mr	r4,r12			/* Pass SRR0 as arg2 */
+	li	r5,0			/* Pass zero as arg3 */
+	EXC_XFER_LITE(0x400, handle_page_fault)
+
+/* 0x0500 - External Interrupt Exception */
+	EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
+
+/* 0x0600 - Alignment Exception */
+	START_EXCEPTION(0x0600, Alignment)
+	NORMAL_EXCEPTION_PROLOG
+	mfspr	r4,SPRN_DEAR		/* Grab the DEAR and save it */
+	stw	r4,_DEAR(r11)
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	EXC_XFER_EE(0x600, alignment_exception)
+
+/* 0x0700 - Program Exception */
+	START_EXCEPTION(0x0700, ProgramCheck)
+	NORMAL_EXCEPTION_PROLOG
+	mfspr	r4,SPRN_ESR		/* Grab the ESR and save it */
+	stw	r4,_ESR(r11)
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	EXC_XFER_STD(0x700, program_check_exception)
+
+	EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x0A00, Trap_0A, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x0B00, Trap_0B, unknown_exception, EXC_XFER_EE)
+
+/* 0x0C00 - System Call Exception */
+	START_EXCEPTION(0x0C00,	SystemCall)
+	NORMAL_EXCEPTION_PROLOG
+	EXC_XFER_EE_LITE(0xc00, DoSyscall)
+
+	EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x0F00, Trap_0F, unknown_exception, EXC_XFER_EE)
+
+/* 0x1000 - Programmable Interval Timer (PIT) Exception */
+	. = 0x1000
+	b Decrementer
+
+/* 0x1010 - Fixed Interval Timer (FIT) Exception
+*/
+	. = 0x1010
+	b FITException
+
+/* 0x1020 - Watchdog Timer (WDT) Exception
+*/
+	. = 0x1020
+	b WDTException
+
+/* 0x1100 - Data TLB Miss Exception
+ * As the name implies, translation is not in the MMU, so search the
+ * page tables and fix it.  The only purpose of this function is to
+ * load TLB entries from the page table if they exist.
+ */
+	START_EXCEPTION(0x1100,	DTLBMiss)
+	mtspr	SPRN_SPRG_SCRATCH0, r10 /* Save some working registers */
+	mtspr	SPRN_SPRG_SCRATCH1, r11
+#ifdef CONFIG_403GCX
+	stw     r12, 0(r0)
+	stw     r9, 4(r0)
+	mfcr    r11
+	mfspr   r12, SPRN_PID
+	stw     r11, 8(r0)
+	stw     r12, 12(r0)
+#else
+	mtspr	SPRN_SPRG_SCRATCH3, r12
+	mtspr	SPRN_SPRG_SCRATCH4, r9
+	mfcr	r11
+	mfspr	r12, SPRN_PID
+	mtspr	SPRN_SPRG_SCRATCH6, r11
+	mtspr	SPRN_SPRG_SCRATCH5, r12
+#endif
+	mfspr	r10, SPRN_DEAR		/* Get faulting address */
+
+	/* If we are faulting a kernel address, we have to use the
+	 * kernel page tables.
+	 */
+	lis	r11, PAGE_OFFSET@h
+	cmplw	r10, r11
+	blt+	3f
+	lis	r11, swapper_pg_dir@h
+	ori	r11, r11, swapper_pg_dir@l
+	li	r9, 0
+	mtspr	SPRN_PID, r9		/* TLB will have 0 TID */
+	b	4f
+
+	/* Get the PGD for the current thread.
+	 */
+3:
+	mfspr	r11,SPRN_SPRG_THREAD
+	lwz	r11,PGDIR(r11)
+4:
+	tophys(r11, r11)
+	rlwimi	r11, r10, 12, 20, 29	/* Create L1 (pgdir/pmd) address */
+	lwz	r12, 0(r11)		/* Get L1 entry */
+	andi.	r9, r12, _PMD_PRESENT	/* Check if it points to a PTE page */
+	beq	2f			/* Bail if no table */
+
+	rlwimi	r12, r10, 22, 20, 29	/* Compute PTE address */
+	lwz	r11, 0(r12)		/* Get Linux PTE */
+	andi.	r9, r11, _PAGE_PRESENT
+	beq	5f
+
+	ori	r11, r11, _PAGE_ACCESSED
+	stw	r11, 0(r12)
+
+	/* Create TLB tag.  This is the faulting address plus a static
+	 * set of bits.  These are size, valid, E, U0.
+	*/
+	li	r12, 0x00c0
+	rlwimi	r10, r12, 0, 20, 31
+
+	b	finish_tlb_load
+
+2:	/* Check for possible large-page pmd entry */
+	rlwinm.	r9, r12, 2, 22, 24
+	beq	5f
+
+	/* Create TLB tag.  This is the faulting address, plus a static
+	 * set of bits (valid, E, U0) plus the size from the PMD.
+	 */
+	ori	r9, r9, 0x40
+	rlwimi	r10, r9, 0, 20, 31
+	mr	r11, r12
+
+	b	finish_tlb_load
+
+5:
+	/* The bailout.  Restore registers to pre-exception conditions
+	 * and call the heavyweights to help us out.
+	 */
+#ifdef CONFIG_403GCX
+	lwz     r12, 12(r0)
+	lwz     r11, 8(r0)
+	mtspr   SPRN_PID, r12
+	mtcr    r11
+	lwz     r9, 4(r0)
+	lwz     r12, 0(r0)
+#else
+	mfspr	r12, SPRN_SPRG_SCRATCH5
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mtspr	SPRN_PID, r12
+	mtcr	r11
+	mfspr	r9, SPRN_SPRG_SCRATCH4
+	mfspr	r12, SPRN_SPRG_SCRATCH3
+#endif
+	mfspr	r11, SPRN_SPRG_SCRATCH1
+	mfspr	r10, SPRN_SPRG_SCRATCH0
+	b	DataAccess
+
+/* 0x1200 - Instruction TLB Miss Exception
+ * Nearly the same as above, except we get our information from different
+ * registers and bailout to a different point.
+ */
+	START_EXCEPTION(0x1200,	ITLBMiss)
+	mtspr	SPRN_SPRG_SCRATCH0, r10	 /* Save some working registers */
+	mtspr	SPRN_SPRG_SCRATCH1, r11
+#ifdef CONFIG_403GCX
+	stw     r12, 0(r0)
+	stw     r9, 4(r0)
+	mfcr    r11
+	mfspr   r12, SPRN_PID
+	stw     r11, 8(r0)
+	stw     r12, 12(r0)
+#else
+	mtspr	SPRN_SPRG_SCRATCH3, r12
+	mtspr	SPRN_SPRG_SCRATCH4, r9
+	mfcr	r11
+	mfspr	r12, SPRN_PID
+	mtspr	SPRN_SPRG_SCRATCH6, r11
+	mtspr	SPRN_SPRG_SCRATCH5, r12
+#endif
+	mfspr	r10, SPRN_SRR0		/* Get faulting address */
+
+	/* If we are faulting a kernel address, we have to use the
+	 * kernel page tables.
+	 */
+	lis	r11, PAGE_OFFSET@h
+	cmplw	r10, r11
+	blt+	3f
+	lis	r11, swapper_pg_dir@h
+	ori	r11, r11, swapper_pg_dir@l
+	li	r9, 0
+	mtspr	SPRN_PID, r9		/* TLB will have 0 TID */
+	b	4f
+
+	/* Get the PGD for the current thread.
+	 */
+3:
+	mfspr	r11,SPRN_SPRG_THREAD
+	lwz	r11,PGDIR(r11)
+4:
+	tophys(r11, r11)
+	rlwimi	r11, r10, 12, 20, 29	/* Create L1 (pgdir/pmd) address */
+	lwz	r12, 0(r11)		/* Get L1 entry */
+	andi.	r9, r12, _PMD_PRESENT	/* Check if it points to a PTE page */
+	beq	2f			/* Bail if no table */
+
+	rlwimi	r12, r10, 22, 20, 29	/* Compute PTE address */
+	lwz	r11, 0(r12)		/* Get Linux PTE */
+	andi.	r9, r11, _PAGE_PRESENT
+	beq	5f
+
+	ori	r11, r11, _PAGE_ACCESSED
+	stw	r11, 0(r12)
+
+	/* Create TLB tag.  This is the faulting address plus a static
+	 * set of bits.  These are size, valid, E, U0.
+	*/
+	li	r12, 0x00c0
+	rlwimi	r10, r12, 0, 20, 31
+
+	b	finish_tlb_load
+
+2:	/* Check for possible large-page pmd entry */
+	rlwinm.	r9, r12, 2, 22, 24
+	beq	5f
+
+	/* Create TLB tag.  This is the faulting address, plus a static
+	 * set of bits (valid, E, U0) plus the size from the PMD.
+	 */
+	ori	r9, r9, 0x40
+	rlwimi	r10, r9, 0, 20, 31
+	mr	r11, r12
+
+	b	finish_tlb_load
+
+5:
+	/* The bailout.  Restore registers to pre-exception conditions
+	 * and call the heavyweights to help us out.
+	 */
+#ifdef CONFIG_403GCX
+	lwz     r12, 12(r0)
+	lwz     r11, 8(r0)
+	mtspr   SPRN_PID, r12
+	mtcr    r11
+	lwz     r9, 4(r0)
+	lwz     r12, 0(r0)
+#else
+	mfspr	r12, SPRN_SPRG_SCRATCH5
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mtspr	SPRN_PID, r12
+	mtcr	r11
+	mfspr	r9, SPRN_SPRG_SCRATCH4
+	mfspr	r12, SPRN_SPRG_SCRATCH3
+#endif
+	mfspr	r11, SPRN_SPRG_SCRATCH1
+	mfspr	r10, SPRN_SPRG_SCRATCH0
+	b	InstructionAccess
+
+	EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1400, Trap_14, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
+#ifdef CONFIG_IBM405_ERR51
+	/* 405GP errata 51 */
+	START_EXCEPTION(0x1700, Trap_17)
+	b DTLBMiss
+#else
+	EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
+#endif
+	EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1A00, Trap_1A, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1B00, Trap_1B, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1C00, Trap_1C, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1D00, Trap_1D, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1E00, Trap_1E, unknown_exception, EXC_XFER_EE)
+	EXCEPTION(0x1F00, Trap_1F, unknown_exception, EXC_XFER_EE)
+
+/* Check for a single step debug exception while in an exception
+ * handler before state has been saved.  This is to catch the case
+ * where an instruction that we are trying to single step causes
+ * an exception (eg ITLB/DTLB miss) and thus the first instruction of
+ * the exception handler generates a single step debug exception.
+ *
+ * If we get a debug trap on the first instruction of an exception handler,
+ * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is
+ * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR).
+ * The exception handler was handling a non-critical interrupt, so it will
+ * save (and later restore) the MSR via SPRN_SRR1, which will still have
+ * the MSR_DE bit set.
+ */
+	/* 0x2000 - Debug Exception */
+	START_EXCEPTION(0x2000, DebugTrap)
+	CRITICAL_EXCEPTION_PROLOG
+
+	/*
+	 * If this is a single step or branch-taken exception in an
+	 * exception entry sequence, it was probably meant to apply to
+	 * the code where the exception occurred (since exception entry
+	 * doesn't turn off DE automatically).  We simulate the effect
+	 * of turning off DE on entry to an exception handler by turning
+	 * off DE in the SRR3 value and clearing the debug status.
+	 */
+	mfspr	r10,SPRN_DBSR		/* check single-step/branch taken */
+	andis.	r10,r10,DBSR_IC@h
+	beq+	2f
+
+	andi.	r10,r9,MSR_IR|MSR_PR	/* check supervisor + MMU off */
+	beq	1f			/* branch and fix it up */
+
+	mfspr   r10,SPRN_SRR2		/* Faulting instruction address */
+	cmplwi  r10,0x2100
+	bgt+    2f			/* address above exception vectors */
+
+	/* here it looks like we got an inappropriate debug exception. */
+1:	rlwinm	r9,r9,0,~MSR_DE		/* clear DE in the SRR3 value */
+	lis	r10,DBSR_IC@h		/* clear the IC event */
+	mtspr	SPRN_DBSR,r10
+	/* restore state and get out */
+	lwz	r10,_CCR(r11)
+	lwz	r0,GPR0(r11)
+	lwz	r1,GPR1(r11)
+	mtcrf	0x80,r10
+	mtspr	SPRN_SRR2,r12
+	mtspr	SPRN_SRR3,r9
+	lwz	r9,GPR9(r11)
+	lwz	r12,GPR12(r11)
+	lwz	r10,crit_r10@l(0)
+	lwz	r11,crit_r11@l(0)
+	PPC405_ERR77_SYNC
+	rfci
+	b	.
+
+	/* continue normal handling for a critical exception... */
+2:	mfspr	r4,SPRN_DBSR
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	EXC_XFER_TEMPLATE(DebugException, 0x2002, \
+		(MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \
+		NOCOPY, crit_transfer_to_handler, ret_from_crit_exc)
+
+	/* Programmable Interval Timer (PIT) Exception. (from 0x1000) */
+Decrementer:
+	NORMAL_EXCEPTION_PROLOG
+	lis	r0,TSR_PIS@h
+	mtspr	SPRN_TSR,r0		/* Clear the PIT exception */
+	addi	r3,r1,STACK_FRAME_OVERHEAD
+	EXC_XFER_LITE(0x1000, timer_interrupt)
+
+	/* Fixed Interval Timer (FIT) Exception. (from 0x1010) */
+FITException:
+	NORMAL_EXCEPTION_PROLOG
+	addi	r3,r1,STACK_FRAME_OVERHEAD;
+	EXC_XFER_EE(0x1010, unknown_exception)
+
+	/* Watchdog Timer (WDT) Exception. (from 0x1020) */
+WDTException:
+	CRITICAL_EXCEPTION_PROLOG;
+	addi	r3,r1,STACK_FRAME_OVERHEAD;
+	EXC_XFER_TEMPLATE(WatchdogException, 0x1020+2,
+	                  (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)),
+			  NOCOPY, crit_transfer_to_handler,
+			  ret_from_crit_exc)
+
+/*
+ * The other Data TLB exceptions bail out to this point
+ * if they can't resolve the lightweight TLB fault.
+ */
+DataAccess:
+	NORMAL_EXCEPTION_PROLOG
+	mfspr	r5,SPRN_ESR		/* Grab the ESR, save it, pass arg3 */
+	stw	r5,_ESR(r11)
+	mfspr	r4,SPRN_DEAR		/* Grab the DEAR, save it, pass arg2 */
+	EXC_XFER_LITE(0x300, handle_page_fault)
+
+/* Other PowerPC processors, namely those derived from the 6xx-series
+ * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved.
+ * However, for the 4xx-series processors these are neither defined nor
+ * reserved.
+ */
+
+	/* Damn, I came up one instruction too many to fit into the
+	 * exception space :-).  Both the instruction and data TLB
+	 * miss get to this point to load the TLB.
+	 * 	r10 - TLB_TAG value
+	 * 	r11 - Linux PTE
+	 *	r12, r9 - available to use
+	 *	PID - loaded with proper value when we get here
+	 *	Upon exit, we reload everything and RFI.
+	 * Actually, it will fit now, but oh well.....a common place
+	 * to load the TLB.
+	 */
+tlb_4xx_index:
+	.long	0
+finish_tlb_load:
+	/* load the next available TLB index.
+	*/
+	lwz	r9, tlb_4xx_index@l(0)
+	addi	r9, r9, 1
+	andi.	r9, r9, (PPC40X_TLB_SIZE-1)
+	stw	r9, tlb_4xx_index@l(0)
+
+6:
+	/*
+	 * Clear out the software-only bits in the PTE to generate the
+	 * TLB_DATA value.  These are the bottom 2 bits of the RPM, the
+	 * top 3 bits of the zone field, and M.
+	 */
+	li	r12, 0x0ce2
+	andc	r11, r11, r12
+
+	tlbwe	r11, r9, TLB_DATA		/* Load TLB LO */
+	tlbwe	r10, r9, TLB_TAG		/* Load TLB HI */
+
+	/* Done...restore registers and get out of here.
+	*/
+#ifdef CONFIG_403GCX
+	lwz     r12, 12(r0)
+	lwz     r11, 8(r0)
+	mtspr   SPRN_PID, r12
+	mtcr    r11
+	lwz     r9, 4(r0)
+	lwz     r12, 0(r0)
+#else
+	mfspr	r12, SPRN_SPRG_SCRATCH5
+	mfspr	r11, SPRN_SPRG_SCRATCH6
+	mtspr	SPRN_PID, r12
+	mtcr	r11
+	mfspr	r9, SPRN_SPRG_SCRATCH4
+	mfspr	r12, SPRN_SPRG_SCRATCH3
+#endif
+	mfspr	r11, SPRN_SPRG_SCRATCH1
+	mfspr	r10, SPRN_SPRG_SCRATCH0
+	PPC405_ERR77_SYNC
+	rfi			/* Should sync shadow TLBs */
+	b	.		/* prevent prefetch past rfi */
+
+/* This is where the main kernel code starts.
+ */
+start_here:
+
+	/* ptr to current */
+	lis	r2,init_task@h
+	ori	r2,r2,init_task@l
+
+	/* ptr to phys current thread */
+	tophys(r4,r2)
+	addi	r4,r4,THREAD	/* init task's THREAD */
+	mtspr	SPRN_SPRG_THREAD,r4
+
+	/* stack */
+	lis	r1,init_thread_union@ha
+	addi	r1,r1,init_thread_union@l
+	li	r0,0
+	stwu	r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
+
+	bl	early_init	/* We have to do this with MMU on */
+
+/*
+ * Decide what sort of machine this is and initialize the MMU.
+ */
+	li	r3,0
+	mr	r4,r31
+	bl	machine_init
+	bl	MMU_init
+
+/* Go back to running unmapped so we can load up new values
+ * and change to using our exception vectors.
+ * On the 4xx, all we have to do is invalidate the TLB to clear
+ * the old 16M byte TLB mappings.
+ */
+	lis	r4,2f@h
+	ori	r4,r4,2f@l
+	tophys(r4,r4)
+	lis	r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h
+	ori	r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l
+	mtspr	SPRN_SRR0,r4
+	mtspr	SPRN_SRR1,r3
+	rfi
+	b	.		/* prevent prefetch past rfi */
+
+/* Load up the kernel context */
+2:
+	sync			/* Flush to memory before changing TLB */
+	tlbia
+	isync			/* Flush shadow TLBs */
+
+	/* set up the PTE pointers for the Abatron bdiGDB.
+	*/
+	lis	r6, swapper_pg_dir@h
+	ori	r6, r6, swapper_pg_dir@l
+	lis	r5, abatron_pteptrs@h
+	ori	r5, r5, abatron_pteptrs@l
+	stw	r5, 0xf0(r0)	/* Must match your Abatron config file */
+	tophys(r5,r5)
+	stw	r6, 0(r5)
+
+/* Now turn on the MMU for real! */
+	lis	r4,MSR_KERNEL@h
+	ori	r4,r4,MSR_KERNEL@l
+	lis	r3,start_kernel@h
+	ori	r3,r3,start_kernel@l
+	mtspr	SPRN_SRR0,r3
+	mtspr	SPRN_SRR1,r4
+	rfi			/* enable MMU and jump to start_kernel */
+	b	.		/* prevent prefetch past rfi */
+
+/* Set up the initial MMU state so we can do the first level of
+ * kernel initialization.  This maps the first 16 MBytes of memory 1:1
+ * virtual to physical and more importantly sets the cache mode.
+ */
+initial_mmu:
+	tlbia			/* Invalidate all TLB entries */
+	isync
+
+	/* We should still be executing code at physical address 0x0000xxxx
+	 * at this point. However, start_here is at virtual address
+	 * 0xC000xxxx. So, set up a TLB mapping to cover this once
+	 * translation is enabled.
+	 */
+
+	lis	r3,KERNELBASE@h		/* Load the kernel virtual address */
+	ori	r3,r3,KERNELBASE@l
+	tophys(r4,r3)			/* Load the kernel physical address */
+
+	iccci	r0,r3			/* Invalidate the i-cache before use */
+
+	/* Load the kernel PID.
+	*/
+	li	r0,0
+	mtspr	SPRN_PID,r0
+	sync
+
+	/* Configure and load one entry into TLB slots 63 */
+	clrrwi	r4,r4,10		/* Mask off the real page number */
+	ori	r4,r4,(TLB_WR | TLB_EX)	/* Set the write and execute bits */
+
+	clrrwi	r3,r3,10		/* Mask off the effective page number */
+	ori	r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M))
+
+        li      r0,63                    /* TLB slot 63 */
+
+	tlbwe	r4,r0,TLB_DATA		/* Load the data portion of the entry */
+	tlbwe	r3,r0,TLB_TAG		/* Load the tag portion of the entry */
+
+	isync
+
+	/* Establish the exception vector base
+	*/
+	lis	r4,KERNELBASE@h		/* EVPR only uses the high 16-bits */
+	tophys(r0,r4)			/* Use the physical address */
+	mtspr	SPRN_EVPR,r0
+
+	blr
+
+_GLOBAL(abort)
+        mfspr   r13,SPRN_DBCR0
+        oris    r13,r13,DBCR0_RST_SYSTEM@h
+        mtspr   SPRN_DBCR0,r13
+
+_GLOBAL(set_context)
+
+#ifdef CONFIG_BDI_SWITCH
+	/* Context switch the PTE pointer for the Abatron BDI2000.
+	 * The PGDIR is the second parameter.
+	 */
+	lis	r5, KERNELBASE@h
+	lwz	r5, 0xf0(r5)
+	stw	r4, 0x4(r5)
+#endif
+	sync
+	mtspr	SPRN_PID,r3
+	isync				/* Need an isync to flush shadow */
+					/* TLBs after changing PID */
+	blr
+
+/* We put a few things here that have to be page-aligned. This stuff
+ * goes at the beginning of the data segment, which is page-aligned.
+ */
+	.data
+	.align	12
+	.globl	sdata
+sdata:
+	.globl	empty_zero_page
+empty_zero_page:
+	.space	4096
+	.globl	swapper_pg_dir
+swapper_pg_dir:
+	.space	PGD_TABLE_SIZE
+
+/* Room for two PTE pointers, usually the kernel and current user pointers
+ * to their respective root page table.
+ */
+abatron_pteptrs:
+	.space	8