path: root/arch/ppc/kernel/head.S

/*
 *  arch/ppc/kernel/head.S
 *
 *  $Id: head.S,v 1.154 1999/10/12 00:33:31 cort Exp $
 *
 *  PowerPC version 
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
 *    Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
 *  Adapted for Power Macintosh by Paul Mackerras.
 *  Low-level exception handlers and MMU support
 *  rewritten by Paul Mackerras.
 *    Copyright (C) 1996 Paul Mackerras.
 *  MPC8xx modifications Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
 *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
 *
 *  This file contains the low-level support and setup for the
 *  PowerPC platform, including trap and interrupt dispatch.
 *  (The PPC 8xx embedded CPUs use head_8xx.S instead.)
 *
 *  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 "ppc_asm.h"
#include <asm/processor.h>
#include <asm/page.h>
#include <linux/config.h>
#include <asm/mmu.h>

#ifdef CONFIG_APUS
#include <asm/amigappc.h>
#endif

#ifdef CONFIG_PPC64
#define LOAD_BAT(n, reg, RA, RB)	\
	ld	RA,(n*32)+0(reg);	\
	ld	RB,(n*32)+8(reg);	\
	mtspr	IBAT##n##U,RA;		\
	mtspr	IBAT##n##L,RB;		\
	ld	RA,(n*32)+16(reg);	\
	ld	RB,(n*32)+24(reg);	\
	mtspr	DBAT##n##U,RA;		\
	mtspr	DBAT##n##L,RB;		\
	
#else /* CONFIG_PPC64 */
	
/* 601 only have IBAT; cr0.eq is set on 601 when using this macro */
#define LOAD_BAT(n, reg, RA, RB)	\
	/* see the comment for clear_bats() -- Cort */ \
	li	RA,0;			\
	mtspr	IBAT##n##U,RA;		\
	mtspr	DBAT##n##U,RA;		\
	lwz	RA,(n*16)+0(reg);	\
	lwz	RB,(n*16)+4(reg);	\
	mtspr	IBAT##n##U,RA;		\
	mtspr	IBAT##n##L,RB;		\
	beq	1f;			\
	lwz	RA,(n*16)+8(reg);	\
	lwz	RB,(n*16)+12(reg);	\
	mtspr	DBAT##n##U,RA;		\
	mtspr	DBAT##n##L,RB;		\
1:	
#endif /* CONFIG_PPC64 */	 
	
	.text
	.globl	_stext
_stext:

/*
 * _start is defined this way because the XCOFF loader in the OpenFirmware
 * on the powermac expects the entry point to be a procedure descriptor.
 */
	.text
	.globl	_start
_start:
	/* 
	 * These are here for legacy reasons, the kernel used to
	 * need to look like a coff function entry for the pmac
	 * but we're always started by some kind of bootloader now.
	 *  -- Cort
	 */
	nop
	nop
	nop

/* PMAC
 * Enter here with the kernel text, data and bss loaded starting at
 * 0, running with virtual == physical mapping.
 * r5 points to the prom entry point (the client interface handler
 * address).  Address translation is turned on, with the prom
 * managing the hash table.  Interrupts are disabled.  The stack
 * pointer (r1) points to just below the end of the half-meg region
 * from 0x380000 - 0x400000, which is mapped in already.
 *
 * If we are booted from MacOS via BootX, we enter with the kernel
 * image loaded somewhere, and the following values in registers:
 *  r3: 'BooX' (0x426f6f58)
 *  r4: virtual address of boot_infos_t
 *  r5: 0
 *
 * APUS
 *   r3: 'APUS'
 *   r4: physical address of memory base
 *   Linux/m68k style BootInfo structure at &_end.
 *
 * PREP
 * This is jumped to on prep systems right after the kernel is relocated
 * to its proper place in memory by the boot loader.  The expected layout
 * of the regs is:	
 *   r3: ptr to residual data
 *   r4: initrd_start or if no initrd then 0
 *   r5: initrd_end - unused if r4 is 0
 *   r6: Start of command line string
 *   r7: End of command line string
 *
 * This just gets a minimal mmu environment setup so we can call
 * start_here() to do the real work.
 * -- Cort
 */
	
	.globl	__start
__start:
#ifdef CONFIG_PPC64
/* 
 * Go into 32-bit mode to boot.  OF should do this for
 * us already but just in case...
 * -- Cort 
 */
	mfmsr	r10
	clrldi	r10,r10,3
	mtmsr	r10
#endif	
/*
 * We have to do any OF calls before we map ourselves to KERNELBASE,
 * because OF may have I/O devices mapped in in that area
 * (particularly on CHRP).
 */
	mr	r31,r3			/* save parameters */
	mr	r30,r4
	mr	r29,r5
	mr	r28,r6
	mr	r27,r7
	li	r24,0			/* cpu # */
	bl	prom_init

#ifdef CONFIG_APUS
/* On APUS the __va/__pa constants need to be set to the correct 
 * values before continuing. 
 */
	mr	r4,r30
	bl	fix_mem_constants
#endif /* CONFIG_APUS */

/*
 * Use the first pair of BAT registers to map the 1st 16MB
 * of RAM to KERNELBASE.  From this point on we can't safely
 * call OF any more.
 */
	lis	r11,KERNELBASE@h
#ifndef CONFIG_PPC64
	mfspr	r9,PVR
	rlwinm	r9,r9,16,16,31		/* r9 = 1 for 601, 4 for 604 */
	cmpi	0,r9,1
	bne	4f
	ori	r11,r11,4		/* set up BAT registers for 601 */
	li	r8,0x7f			/* valid, block length = 8MB */
	oris	r9,r11,0x800000@h	/* set up BAT reg for 2nd 8M */
	oris	r10,r8,0x800000@h	/* set up BAT reg for 2nd 8M */
	mtspr	IBAT0U,r11		/* N.B. 601 has valid bit in */
	mtspr	IBAT0L,r8		/* lower BAT register */
	mtspr	IBAT1U,r9
	mtspr	IBAT1L,r10
	b	5f
#endif /* CONFIG_PPC64 */

4:	tophys(r8,r11)
#ifdef __SMP__
	ori	r8,r8,0x12		/* R/W access, M=1 */
#else
	ori	r8,r8,2			/* R/W access */
#endif /* __SMP__ */
#ifdef CONFIG_APUS
	ori	r11,r11,BL_8M<<2|0x2	/* set up 8MB BAT registers for 604 */
#else
	ori	r11,r11,BL_256M<<2|0x2	/* set up BAT registers for 604 */
#endif /* CONFIG_APUS */
	
#ifdef CONFIG_PPC64
	/* clear out the high 32 bits in the BAT */
	clrldi	r11,r11,32
	clrldi	r8,r8,32
	/* turn off the pagetable mappings just in case */
	clrldi	r16,r16,63
	mtsdr1	r16
#else /* CONFIG_PPC64 */
	/*
	 * If the MMU is off clear the bats.  See clear_bat() -- Cort
	 */
	mfmsr	r20
	andi.	r20,r20,MSR_DR
	bne	100f
	bl	clear_bats
100:
#endif /* CONFIG_PPC64 */
	mtspr	DBAT0L,r8		/* N.B. 6xx (not 601) have valid */
	mtspr	DBAT0U,r11		/* bit in upper BAT register */
	mtspr	IBAT0L,r8
	mtspr	IBAT0U,r11
5:	isync

#ifndef CONFIG_APUS
/*
 * We need to run with _start at physical address 0.
 * On CHRP, we are loaded at 0x10000 since OF on CHRP uses
 * the exception vectors at 0 (and therefore this copy
 * overwrites OF's exception vectors with our own).
 * If the MMU is already turned on, we copy stuff to KERNELBASE,
 * otherwise we copy it to 0.
 */
	bl	reloc_offset
	mr	r26,r3
	addis	r4,r3,KERNELBASE@h	/* current address of _start */
	cmpwi	0,r4,0			/* are we already running at 0? */
	beq	2f			/* assume it's OK if so */
	li	r3,0
	mfmsr	r0
	andi.	r0,r0,MSR_DR		/* MMU enabled? */
	beq	relocate_kernel
	lis	r3,KERNELBASE@h		/* if so, are we */
	cmpw	0,r4,r3			/* already running at KERNELBASE? */
	bne	relocate_kernel
2:
#endif /* CONFIG_APUS */
/*
 * we now have the 1st 16M of ram mapped with the bats.
 * prep needs the mmu to be turned on here, but pmac already has it on.
 * this shouldn't bother the pmac since it just gets turned on again
 * as we jump to our code at KERNELBASE. -- Cort
 */
turn_on_mmu:
	mfmsr	r0
	ori	r0,r0,MSR_DR|MSR_IR
	mtspr	SRR1,r0
	lis	r0,start_here@h
	ori	r0,r0,start_here@l
	mtspr	SRR0,r0
	SYNC
	rfi				/* enables MMU */

/*
 * Exception entry code.  This code runs with address translation
 * turned off, i.e. using physical addresses.
 * We assume sprg3 has the physical address of the current
 * task's thread_struct.
 */
#define EXCEPTION_PROLOG	\
	mtspr	SPRG0,r20;	\
	mtspr	SPRG1,r21;	\
	mfcr	r20;		\
	mfspr	r21,SPRG2;		/* exception stack to use from */ \
	cmpwi	0,r21,0;		/* user mode or RTAS */ \
	bne	1f;		\
	tophys(r21,r1);			/* use tophys(kernel sp) otherwise */ \
	subi	r21,r21,INT_FRAME_SIZE;	/* alloc exc. frame */\
1:	stw	r20,_CCR(r21);		/* save registers */ \
	stw	r22,GPR22(r21);	\
	stw	r23,GPR23(r21);	\
	mfspr	r20,SPRG0;	\
	stw	r20,GPR20(r21);	\
	mfspr	r22,SPRG1;	\
	stw	r22,GPR21(r21);	\
	mflr	r20;		\
	stw	r20,_LINK(r21);	\
	mfctr	r22;		\
	stw	r22,_CTR(r21);	\
	mfspr	r20,XER;	\
	stw	r20,_XER(r21);	\
	mfspr	r22,SRR0;	\
	mfspr	r23,SRR1;	\
	stw	r0,GPR0(r21);	\
	stw	r1,GPR1(r21);	\
	stw	r2,GPR2(r21);	\
	stw	r1,0(r21);	\
	tovirt(r1,r21);			/* set new kernel sp */	\
	SAVE_4GPRS(3, r21);
/*
 * Note: code which follows this uses cr0.eq (set if from kernel),
 * r21, r22 (SRR0), and r23 (SRR1).
 */

/*
 * Exception vectors.
 */
#define STD_EXCEPTION(n, label, hdlr)		\
	. = n;					\
label:						\
	EXCEPTION_PROLOG;			\
	addi	r3,r1,STACK_FRAME_OVERHEAD;	\
	li	r20,MSR_KERNEL;			\
	bl	transfer_to_handler; 		\
	.long	hdlr;				\
	.long	ret_from_except

/* System reset */
#ifdef CONFIG_SMP /* MVME/MTX and gemini start the secondary here */
#ifdef CONFIG_GEMINI
	. = 0x100
	b	__secondary_start_gemini
#else /* CONFIG_GEMINI */
	STD_EXCEPTION(0x100, Reset, __secondary_start_psurge)
#endif /* CONFIG_GEMINI */
#else
	STD_EXCEPTION(0x100, Reset, UnknownException)
#endif

/* Machine check */
	STD_EXCEPTION(0x200, MachineCheck, MachineCheckException)

/* Data access exception. */
	. = 0x300
DataAccess:
	EXCEPTION_PROLOG
	mfspr	r20,DSISR
	andis.	r0,r20,0xa470		/* weird error? */
	bne	1f			/* if not, try to put a PTE */
	mfspr	r3,DAR			/* into the hash table */
	rlwinm	r4,r23,32-13,30,30	/* MSR_PR -> _PAGE_USER */
	rlwimi	r4,r20,32-23,29,29	/* DSISR_STORE -> _PAGE_RW */
	bl	hash_page
1:	stw	r20,_DSISR(r21)
	mr	r5,r20
	mfspr	r4,DAR
	stw	r4,_DAR(r21)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	li	r20,MSR_KERNEL
	rlwimi	r20,r23,0,16,16		/* copy EE bit from saved MSR */
	bl	transfer_to_handler
	.long	do_page_fault
	.long	ret_from_except

/* Instruction access exception. */
	. = 0x400
InstructionAccess:
	EXCEPTION_PROLOG
	andis.	r0,r23,0x4000		/* no pte found? */
	beq	1f			/* if so, try to put a PTE */
	mr	r3,r22			/* into the hash table */
	rlwinm	r4,r23,32-13,30,30	/* MSR_PR -> _PAGE_USER */
	mr	r20,r23			/* SRR1 has reason bits */
	bl	hash_page
1:	addi	r3,r1,STACK_FRAME_OVERHEAD
	mr	r4,r22
	mr	r5,r23
	li	r20,MSR_KERNEL
	rlwimi	r20,r23,0,16,16		/* copy EE bit from saved MSR */
	bl	transfer_to_handler
	.long	do_page_fault
	.long	ret_from_except

/* External interrupt */
	. = 0x500;
HardwareInterrupt:
#ifndef CONFIG_APUS
	EXCEPTION_PROLOG;
	addi	r3,r1,STACK_FRAME_OVERHEAD
	li	r20,MSR_KERNEL
	li	r4,0
	bl	transfer_to_handler
	.globl do_IRQ_intercept
do_IRQ_intercept:
	.long	do_IRQ;
	.long	ret_from_except
#else
 	EXCEPTION_PROLOG;
 	addi	r3,r1,STACK_FRAME_OVERHEAD
 	li	r20,MSR_KERNEL
	bl	apus_interrupt_entry
#endif /* CONFIG_APUS */

/* Alignment exception */
	. = 0x600
Alignment:
	EXCEPTION_PROLOG
	mfspr	r4,DAR
	stw	r4,_DAR(r21)
	mfspr	r5,DSISR
	stw	r5,_DSISR(r21)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	li	r20,MSR_KERNEL
	rlwimi	r20,r23,0,16,16		/* copy EE bit from saved MSR */
	bl	transfer_to_handler
	.long	AlignmentException
	.long	ret_from_except

/* Program check exception */
	. = 0x700
ProgramCheck:
	EXCEPTION_PROLOG
	addi	r3,r1,STACK_FRAME_OVERHEAD
	li	r20,MSR_KERNEL
	rlwimi	r20,r23,0,16,16		/* copy EE bit from saved MSR */
	bl	transfer_to_handler
	.long	ProgramCheckException
	.long	ret_from_except

/* Floating-point unavailable */
	. = 0x800
FPUnavailable:
	EXCEPTION_PROLOG
	bne	load_up_fpu		/* if from user, just load it up */
	li	r20,MSR_KERNEL
	bl	transfer_to_handler	/* if from kernel, take a trap */
	.long	KernelFP
	.long	ret_from_except

	. = 0x900
Decrementer:
	EXCEPTION_PROLOG
	addi	r3,r1,STACK_FRAME_OVERHEAD
	li	r20,MSR_KERNEL
	bl	transfer_to_handler
	.globl timer_interrupt_intercept
timer_interrupt_intercept:
	.long	timer_interrupt
	.long	ret_from_except

	STD_EXCEPTION(0xa00, Trap_0a, UnknownException)
	STD_EXCEPTION(0xb00, Trap_0b, UnknownException)

/* System call */
	. = 0xc00
SystemCall:
	EXCEPTION_PROLOG
	stw	r3,ORIG_GPR3(r21)
	li	r20,MSR_KERNEL
	rlwimi	r20,r23,0,16,16		/* copy EE bit from saved MSR */
	bl	transfer_to_handler
	.long	DoSyscall
	.long	ret_from_except

/* Single step - not used on 601 */
	STD_EXCEPTION(0xd00, SingleStep, SingleStepException)

	STD_EXCEPTION(0xe00, Trap_0e, UnknownException)
	STD_EXCEPTION(0xf00, Trap_0f, UnknownException)

/*
 * Handle TLB miss for instruction on 603/603e.
 * Note: we get an alternate set of r0 - r3 to use automatically.
 */
	. = 0x1000
InstructionTLBMiss:
/*
 * r0:	stored ctr
 * r1:	linux style pte ( later becomes ppc hardware pte )
 * r2:	ptr to linux-style pte
 * r3:	scratch
 */
	mfctr	r0
	/* Get PTE (linux-style) and check access */
	mfspr	r2,SPRG3
	lwz	r2,PGDIR(r2)
	tophys(r2,r2)
	mfspr	r3,IMISS
	rlwimi	r2,r3,12,20,29		/* insert top 10 bits of address */
	lwz	r2,0(r2)		/* get pmd entry */
	rlwinm.	r2,r2,0,0,19		/* extract address of pte page */
	beq-	InstructionAddressInvalid	/* return if no mapping */
	tophys(r2,r2)
	rlwimi	r2,r3,22,20,29		/* insert next 10 bits of address */
	lwz	r1,0(r2)		/* get linux-style pte */
	/* setup access flags in r3 */
	mfmsr	r3
	rlwinm	r3,r3,32-13,30,30	/* MSR_PR -> _PAGE_USER */
	ori	r3,r3,1			/* set _PAGE_PRESENT bit in access */
	andc.	r3,r3,r1		/* check access & ~permission */
	bne-	InstructionAddressInvalid /* return if access not permitted */
	ori	r1,r1,0x100		/* set _PAGE_ACCESSED in pte */
	stw	r1,0(r2)		/* update PTE (accessed bit) */
	/* Convert linux-style PTE to low word of PPC-style PTE */
	/* this computation could be done better -- Cort */
	rlwinm	r3,r1,32-9,31,31	/* _PAGE_HWWRITE -> PP lsb */
	rlwimi	r1,r1,32-1,31,31	/* _PAGE_USER -> PP (both bits now) */
	ori	r3,r3,0xe04		/* clear out reserved bits */
	andc	r1,r1,r3		/* PP=2 or 0, when _PAGE_HWWRITE */
	mtspr	RPA,r1
	mfspr	r3,IMISS
	tlbli	r3
	mfspr	r3,SRR1		/* Need to restore CR0 */
	mtcrf	0x80,r3
	rfi	
InstructionAddressInvalid:
	mfspr	r3,SRR1
	rlwinm	r1,r3,9,6,6	/* Get load/store bit */

	addis	r1,r1,0x2000
	mtspr	DSISR,r1	/* (shouldn't be needed) */
	mtctr	r0		/* Restore CTR */
	andi.	r2,r3,0xFFFF	/* Clear upper bits of SRR1 */
	or	r2,r2,r1
	mtspr	SRR1,r2
	mfspr	r1,IMISS	/* Get failing address */
	rlwinm.	r2,r2,0,31,31	/* Check for little endian access */
	rlwimi	r2,r2,1,30,30	/* change 1 -> 3 */
	xor	r1,r1,r2
	mtspr	DAR,r1		/* Set fault address */
	mfmsr	r0		/* Restore "normal" registers */
	xoris	r0,r0,MSR_TGPR>>16
	mtcrf	0x80,r3		/* Restore CR0 */
	sync			/* Some chip revs have problems here... */
	mtmsr	r0
	b	InstructionAccess

/*
 * Handle TLB miss for DATA Load operation on 603/603e
 */
	. = 0x1100
DataLoadTLBMiss:
/*
 * r0:	stored ctr
 * r1:	linux style pte ( later becomes ppc hardware pte )
 * r2:	ptr to linux-style pte
 * r3:	scratch
 */
	mfctr	r0
	/* Get PTE (linux-style) and check access */
	mfspr	r2,SPRG3
	lwz	r2,PGDIR(r2)
	tophys(r2,r2)
	mfspr	r3,DMISS
	rlwimi	r2,r3,12,20,29		/* insert top 10 bits of address */
	lwz	r2,0(r2)		/* get pmd entry */
	rlwinm.	r2,r2,0,0,19		/* extract address of pte page */
	beq-	DataAddressInvalid	/* return if no mapping */
	tophys(r2,r2)
	rlwimi	r2,r3,22,20,29		/* insert next 10 bits of address */
	lwz	r1,0(r2)		/* get linux-style pte */
	/* setup access flags in r3 */
	mfmsr	r3
	rlwinm	r3,r3,32-13,30,30	/* MSR_PR -> _PAGE_USER */
	ori	r3,r3,1			/* set _PAGE_PRESENT bit in access */
	/* save r2 and use it as scratch for the andc. */	
	andc.	r3,r3,r1		/* check access & ~permission */
	bne-	DataAddressInvalid	/* return if access not permitted */
	ori	r1,r1,0x100		/* set _PAGE_ACCESSED in pte */
	stw	r1,0(r2)		/* update PTE (accessed bit) */
	/* Convert linux-style PTE to low word of PPC-style PTE */
	/* this computation could be done better -- Cort */
	rlwinm	r3,r1,32-9,31,31	/* _PAGE_HWWRITE -> PP lsb */
	rlwimi	r1,r1,32-1,31,31	/* _PAGE_USER -> PP (both bits now) */
	ori	r3,r3,0xe04		/* clear out reserved bits */
	andc	r1,r1,r3		/* PP=2 or 0, when _PAGE_HWWRITE */
	mtspr	RPA,r1
	mfspr	r3,DMISS
	tlbld	r3
	mfspr	r3,SRR1		/* Need to restore CR0 */
	mtcrf	0x80,r3
	rfi	
DataAddressInvalid:
	mfspr	r3,SRR1
	rlwinm	r1,r3,9,6,6	/* Get load/store bit */
	addis	r1,r1,0x2000
	mtspr	DSISR,r1
	mtctr	r0		/* Restore CTR */
	andi.	r2,r3,0xFFFF	/* Clear upper bits of SRR1 */
	mtspr	SRR1,r2
	mfspr	r1,DMISS	/* Get failing address */
	rlwinm.	r2,r2,0,31,31	/* Check for little endian access */
	beq	20f		/* Jump if big endian */
	xori	r1,r1,3
20:	mtspr	DAR,r1		/* Set fault address */
	mfmsr	r0		/* Restore "normal" registers */
	xoris	r0,r0,MSR_TGPR>>16
	mtcrf	0x80,r3		/* Restore CR0 */
	sync			/* Some chip revs have problems here... */
	mtmsr	r0
	b	DataAccess
	
/*
 * Handle TLB miss for DATA Store on 603/603e
 */
	. = 0x1200
DataStoreTLBMiss:
/*
 * r0:	stored ctr
 * r1:	linux style pte ( later becomes ppc hardware pte )
 * r2:	ptr to linux-style pte
 * r3:	scratch
 */
	mfctr	r0
	/* Get PTE (linux-style) and check access */
	mfspr	r2,SPRG3
	lwz	r2,PGDIR(r2)
	tophys(r2,r2)
	mfspr	r3,DMISS
	rlwimi	r2,r3,12,20,29		/* insert top 10 bits of address */
	lwz	r2,0(r2)		/* get pmd entry */
	rlwinm.	r2,r2,0,0,19		/* extract address of pte page */
	beq-	DataAddressInvalid	/* return if no mapping */
	tophys(r2,r2)
	rlwimi	r2,r3,22,20,29		/* insert next 10 bits of address */
	lwz	r1,0(r2)		/* get linux-style pte */
	/* setup access flags in r3 */
	mfmsr	r3
	rlwinm	r3,r3,32-13,30,30	/* MSR_PR -> _PAGE_USER */
	ori	r3,r3,0x5		/* _PAGE_PRESENT|_PAGE_RW */
	/* save r2 and use it as scratch for the andc. */	
	andc.	r3,r3,r1		/* check access & ~permission */
	bne-	DataAddressInvalid	/* return if access not permitted */
	ori	r1,r1,0x384		/* set _PAGE_ACCESSED|_PAGE_DIRTY|_PAGE_RW|_PAGE_HWWRITE in pte */
	stw	r1,0(r2)		/* update PTE (accessed bit) */
	/* Convert linux-style PTE to low word of PPC-style PTE */
	/* this computation could be done better -- Cort */
	rlwinm	r3,r1,32-9,31,31	/* _PAGE_HWWRITE -> PP lsb */
	rlwimi	r1,r1,32-1,31,31	/* _PAGE_USER -> PP (both bits now) */
	ori	r3,r3,0xe04		/* clear out reserved bits */
	andc	r1,r1,r3		/* PP=2 or 0, when _PAGE_HWWRITE */
	mtspr	RPA,r1
	mfspr	r3,DMISS
	tlbld	r3
	mfspr	r3,SRR1		/* Need to restore CR0 */
	mtcrf	0x80,r3
	rfi	

/* Instruction address breakpoint exception (on 603/604) */
	STD_EXCEPTION(0x1300, Trap_13, InstructionBreakpoint)

/* System management exception (603?) */
	STD_EXCEPTION(0x1400, Trap_14, UnknownException)

	STD_EXCEPTION(0x1500, Trap_15, UnknownException)
	STD_EXCEPTION(0x1600, Trap_16, UnknownException)
	STD_EXCEPTION(0x1700, Trap_17, TAUException)
	STD_EXCEPTION(0x1800, Trap_18, UnknownException)
	STD_EXCEPTION(0x1900, Trap_19, UnknownException)
	STD_EXCEPTION(0x1a00, Trap_1a, UnknownException)
	STD_EXCEPTION(0x1b00, Trap_1b, UnknownException)
	STD_EXCEPTION(0x1c00, Trap_1c, UnknownException)
	STD_EXCEPTION(0x1d00, Trap_1d, UnknownException)
	STD_EXCEPTION(0x1e00, Trap_1e, UnknownException)
	STD_EXCEPTION(0x1f00, Trap_1f, UnknownException)

	/* Run mode exception */
	STD_EXCEPTION(0x2000, RunMode, RunModeException)

	STD_EXCEPTION(0x2100, Trap_21, UnknownException)
	STD_EXCEPTION(0x2200, Trap_22, UnknownException)
	STD_EXCEPTION(0x2300, Trap_23, UnknownException)
	STD_EXCEPTION(0x2400, Trap_24, UnknownException)
	STD_EXCEPTION(0x2500, Trap_25, UnknownException)
	STD_EXCEPTION(0x2600, Trap_26, UnknownException)
	STD_EXCEPTION(0x2700, Trap_27, UnknownException)
	STD_EXCEPTION(0x2800, Trap_28, UnknownException)
	STD_EXCEPTION(0x2900, Trap_29, UnknownException)
	STD_EXCEPTION(0x2a00, Trap_2a, UnknownException)
	STD_EXCEPTION(0x2b00, Trap_2b, UnknownException)
	STD_EXCEPTION(0x2c00, Trap_2c, UnknownException)
	STD_EXCEPTION(0x2d00, Trap_2d, UnknownException)
	STD_EXCEPTION(0x2e00, Trap_2e, UnknownException)
	STD_EXCEPTION(0x2f00, Trap_2f, UnknownException)

	. = 0x3000

/*
 * This code finishes saving the registers to the exception frame
 * and jumps to the appropriate handler for the exception, turning
 * on address translation.
 */
	.globl	transfer_to_handler
transfer_to_handler:
	stw	r22,_NIP(r21)
	stw	r23,_MSR(r21)
	SAVE_GPR(7, r21)
	SAVE_4GPRS(8, r21)
	SAVE_8GPRS(12, r21)
	SAVE_8GPRS(24, r21)
	andi.	r23,r23,MSR_PR
	mfspr	r23,SPRG3		/* if from user, fix up THREAD.regs */
	beq	2f
	addi	r24,r1,STACK_FRAME_OVERHEAD
	stw	r24,PT_REGS(r23)
2:	addi	r2,r23,-THREAD		/* set r2 to current */
	tovirt(r2,r2)
	mflr	r23
	andi.	r24,r23,0x3f00		/* get vector offset */
	stw	r24,TRAP(r21)
	li	r22,RESULT
	stwcx.	r22,r22,r21		/* to clear the reservation */
	li	r22,0
	stw	r22,RESULT(r21)
	mtspr	SPRG2,r22		/* r1 is now kernel sp */
	addi	r24,r2,TASK_STRUCT_SIZE	/* check for kernel stack overflow */
	cmplw	0,r1,r2
	cmplw	1,r1,r24
	crand	1,1,4
	bgt-	stack_ovf		/* if r2 < r1 < r2+TASK_STRUCT_SIZE */
	lwz	r24,0(r23)		/* virtual address of handler */
	lwz	r23,4(r23)		/* where to go when done */
	mtspr	SRR0,r24
	mtspr	SRR1,r20
	mtlr	r23
	SYNC
	rfi				/* jump to handler, enable MMU */

/*
 * On kernel stack overflow, load up an initial stack pointer
 * and call StackOverflow(regs), which should not return.
 */
stack_ovf:
	addi	r3,r1,STACK_FRAME_OVERHEAD
	lis	r1,init_task_union@ha
	addi	r1,r1,init_task_union@l
	addi	r1,r1,TASK_UNION_SIZE-STACK_FRAME_OVERHEAD
	lis	r24,StackOverflow@ha
	addi	r24,r24,StackOverflow@l
	li	r20,MSR_KERNEL
	mtspr	SRR0,r24
	mtspr	SRR1,r20
	SYNC
	rfi

/*
 * Disable FP for the task which had the FPU previously,
 * and save its floating-point registers in its thread_struct.
 * Enables the FPU for use in the kernel on return.
 * On SMP we know the fpu is free, since we give it up every
 * switch.  -- Cort
 */
load_up_fpu:
	mfmsr	r5
	ori	r5,r5,MSR_FP
	SYNC
	mtmsr	r5			/* enable use of fpu now */
	SYNC
/*
 * For SMP, we don't do lazy FPU switching because it just gets too
 * horrendously complex, especially when a task switches from one CPU
 * to another.  Instead we call giveup_fpu in switch_to.
 */
#ifndef __SMP__
	lis	r6,0                    /* get __pa constant */
	tophys(r6,r6)
	addis	r3,r6,last_task_used_math@ha
	lwz	r4,last_task_used_math@l(r3)
	cmpi	0,r4,0
	beq	1f
	add	r4,r4,r6
	addi	r4,r4,THREAD	        /* want THREAD of last_task_used_math */
	SAVE_32FPRS(0, r4)
	mffs	fr0
	stfd	fr0,THREAD_FPSCR-4(r4)
	lwz	r5,PT_REGS(r4)
	add	r5,r5,r6
	lwz	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
	li	r20,MSR_FP|MSR_FE0|MSR_FE1
	andc	r4,r4,r20		/* disable FP for previous task */
	stw	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#endif /* __SMP__ */
	/* enable use of FP after return */
	ori	r23,r23,MSR_FP|MSR_FE0|MSR_FE1
	mfspr	r5,SPRG3		/* current task's THREAD (phys) */
	lfd	fr0,THREAD_FPSCR-4(r5)
	mtfsf	0xff,fr0
	REST_32FPRS(0, r5)
#ifndef __SMP__
	subi	r4,r5,THREAD
	sub	r4,r4,r6
	stw	r4,last_task_used_math@l(r3)
#endif /* __SMP__ */
	/* restore registers and return */
	lwz	r3,_CCR(r21)
	lwz	r4,_LINK(r21)
	mtcrf	0xff,r3
	mtlr	r4
	REST_GPR(1, r21)
	REST_4GPRS(3, r21)
	/* we haven't used ctr or xer */
	mtspr	SRR1,r23
	mtspr	SRR0,r22
	REST_GPR(20, r21)
	REST_2GPRS(22, r21)
	lwz	r21,GPR21(r21)
	SYNC
	rfi
	
/*
 * FP unavailable trap from kernel - print a message, but let
 * the task use FP in the kernel until it returns to user mode.
 */
KernelFP:
	lwz	r3,_MSR(r1)
	ori	r3,r3,MSR_FP
	stw	r3,_MSR(r1)		/* enable use of FP after return */
	lis	r3,86f@h
	ori	r3,r3,86f@l
	mr	r4,r2			/* current */
	lwz	r5,_NIP(r1)
	bl	printk
	b	ret_from_except
86:	.string	"floating point used in kernel (task=%p, pc=%x)\n"
	.align	4

/*
 * giveup_fpu(tsk)
 * Disable FP for the task given as the argument,
 * and save the floating-point registers in its thread_struct.
 * Enables the FPU for use in the kernel on return.
 */
	.globl	giveup_fpu
giveup_fpu:
	mfmsr	r5
	ori	r5,r5,MSR_FP
	SYNC
	mtmsr	r5			/* enable use of fpu now */
	SYNC
	cmpi	0,r3,0
	beqlr-				/* if no previous owner, done */
	addi	r3,r3,THREAD	        /* want THREAD of task */
	lwz	r5,PT_REGS(r3)
	cmpi	0,r5,0
	SAVE_32FPRS(0, r3)
	mffs	fr0
	stfd	fr0,THREAD_FPSCR-4(r3)
	beq	1f
	lwz	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
	li	r3,MSR_FP|MSR_FE0|MSR_FE1
	andc	r4,r4,r3		/* disable FP for previous task */
	stw	r4,_MSR-STACK_FRAME_OVERHEAD(r5)
1:
#ifndef __SMP__
	li	r5,0
	lis	r4,last_task_used_math@ha
	stw	r5,last_task_used_math@l(r4)
#endif /* __SMP__ */
	blr

/*
 * This code is jumped to from the startup code to copy
 * the kernel image to physical address 0.
 */
relocate_kernel:
	lis	r9,0x426f		/* if booted from BootX, don't */
	addi	r9,r9,0x6f58		/* translate source addr */
	cmpw	r31,r9			/* (we have to on chrp) */
	beq	7f
	rlwinm	r4,r4,0,8,31		/* translate source address */
	add	r4,r4,r3		/* to region mapped with BATs */
7:	addis	r9,r26,klimit@ha	/* fetch klimit */
	lwz	r25,klimit@l(r9)
	addis	r25,r25,-KERNELBASE@h
	li	r6,0			/* Destination offset */
	li	r5,0x4000		/* # bytes of memory to copy */
	bl	copy_and_flush		/* copy the first 0x4000 bytes */
	addi	r0,r3,4f@l		/* jump to the address of 4f */
	mtctr	r0			/* in copy and do the rest. */
	bctr				/* jump to the copy */
4:	mr	r5,r25
	bl	copy_and_flush		/* copy the rest */
	b	turn_on_mmu

/*
 * Copy routine used to copy the kernel to start at physical address 0
 * and flush and invalidate the caches as needed.
 * r3 = dest addr, r4 = source addr, r5 = copy limit, r6 = start offset
 * on exit, r3, r4, r5 are unchanged, r6 is updated to be >= r5.
 */
copy_and_flush:
	addi	r5,r5,-4
	addi	r6,r6,-4
4:	li	r0,8
	mtctr	r0
3:	addi	r6,r6,4			/* copy a cache line */
	lwzx	r0,r6,r4
	stwx	r0,r6,r3
	bdnz	3b
	dcbst	r6,r3			/* write it to memory */
	sync
	icbi	r6,r3			/* flush the icache line */
	cmplw	0,r6,r5
	blt	4b
	isync
	addi	r5,r5,4
	addi	r6,r6,4
	blr

#ifdef CONFIG_APUS
/*
 * On APUS the physical base address of the kernel is not known at compile
 * time, which means the __pa/__va constants used are incorect. In the
 * __init section is recorded the virtual addresses of instructions using
 * these constants, so all that has to be done is fix these before
 * continuing the kernel boot.
 *
 * r4 = The physical address of the kernel base.
 */
fix_mem_constants:
	mr	r10,r4
	addis	r10,r10,-KERNELBASE@h    /* virt_to_phys constant */
	neg	r11,r10	                 /* phys_to_virt constant */

	lis	r12,__vtop_table_begin@h
	ori	r12,r12,__vtop_table_begin@l
	add	r12,r12,r10	         /* table begin phys address */
	lis	r13,__vtop_table_end@h
	ori	r13,r13,__vtop_table_end@l
	add	r13,r13,r10	         /* table end phys address */
	subi	r12,r12,4
	subi	r13,r13,4
1:	lwzu	r14,4(r12)               /* virt address of instruction */
	add     r14,r14,r10              /* phys address of instruction */
	lwz     r15,0(r14)               /* instruction, now insert top */
	rlwimi  r15,r10,16,16,31         /* half of vp const in low half */
	stw	r15,0(r14)               /* of instruction and restore. */
	dcbst	r0,r14			 /* write it to memory */
	sync
	icbi	r0,r14			 /* flush the icache line */
	cmpw	r12,r13
	bne     1b

/*
 * Map the memory where the exception handlers will
 * be copied to when hash constants have been patched.  
 */
#ifdef CONFIG_APUS_FAST_EXCEPT
	lis	r8,0xfff0
#else
	lis	r8,0
#endif
	ori	r8,r8,0x2		/* 128KB, supervisor */
	mtspr	DBAT3U,r8
	mtspr	DBAT3L,r8

	lis	r12,__ptov_table_begin@h
	ori	r12,r12,__ptov_table_begin@l
	add	r12,r12,r10	         /* table begin phys address */
	lis	r13,__ptov_table_end@h
	ori	r13,r13,__ptov_table_end@l
	add	r13,r13,r10	         /* table end phys address */
	subi	r12,r12,4
	subi	r13,r13,4
1:	lwzu	r14,4(r12)               /* virt address of instruction */
	add     r14,r14,r10              /* phys address of instruction */
	lwz     r15,0(r14)               /* instruction, now insert top */
	rlwimi  r15,r11,16,16,31         /* half of pv const in low half*/
	stw	r15,0(r14)               /* of instruction and restore. */
	dcbst	r0,r14			 /* write it to memory */
	sync
	icbi	r0,r14			 /* flush the icache line */
	cmpw	r12,r13
	bne     1b

	isync				/* No speculative loading until now */
	blr

       /* On APUS the first 0x4000 bytes of the kernel will be mapped
        * at a different physical address than the rest. For this
        * reason, the exception code cannot use relative branches to
        * access the code below.
        */
	. = 0x4000
#endif

#ifdef CONFIG_SMP
	.globl	__secondary_hold
__secondary_hold:
	/* tell the master we're here */
	lis	r5,0x4@h
	ori	r5,r5,0x4@l
	stw	r3,0(r5)
	dcbf	0,r5
100:
	lis	r5,0
	dcbi	0,r5
	lwz	r4,0(r5)
	/* wait until we're told to start */
	cmp	0,r4,r3
	bne	100b
	/* our cpu # was at addr 0 - go */
	lis	r5,__secondary_start@h
	ori	r5,r5,__secondary_start@l
	tophys(r5,r5)
	mtlr	r5
	mr	r24,r3			/* cpu # */
	blr
#ifdef CONFIG_GEMINI
	.globl	__secondary_start_gemini
__secondary_start_gemini:
        mfspr   r4,HID0
        ori     r4,r4,HID0_ICFI
        li      r3,0
        ori     r3,r3,HID0_ICE
        andc    r4,r4,r3
        mtspr   HID0,r4
        sync
        bl      prom_init
        b       __secondary_start
#endif /* CONFIG_GEMINI */
	
	.globl	__secondary_start_psurge
__secondary_start_psurge:
	li	r24,1			/* cpu # */
	/* we come in here with IR=0 and DR=1, and DBAT 0
	   set to map the 0xf0000000 - 0xffffffff region */
	mfmsr	r0
	rlwinm	r0,r0,0,28,26		/* clear DR (0x10) */
	sync
	mtmsr	r0
	isync

	.globl	__secondary_start
__secondary_start:
	bl	enable_caches

	/* get current */
	lis	r2,current_set@h
	ori	r2,r2,current_set@l
	tophys(r2,r2)
	slwi	r24,r24,2		/* get current_set[cpu#] */
	lwzx	r2,r2,r24

	/* stack */
	addi	r1,r2,TASK_UNION_SIZE-STACK_FRAME_OVERHEAD
	li	r0,0
	tophys(r3,r1)
	stw	r0,0(r3)

	/* load up the MMU */
	bl	load_up_mmu

	/* ptr to phys current thread */
	tophys(r4,r2)
	addi	r4,r4,THREAD	/* phys address of our thread_struct */
	mtspr	SPRG3,r4
	li	r3,0
	mtspr	SPRG2,r3	/* 0 => r1 has kernel sp */

	/* enable MMU and jump to start_secondary */
	li	r4,MSR_KERNEL
	lis	r3,start_secondary@h
	ori	r3,r3,start_secondary@l
	mtspr	SRR0,r3
	mtspr	SRR1,r4
	rfi

#endif /* CONFIG_SMP */

/*
 * Enable caches and 604-specific features if necessary.
 */
enable_caches:
	mfspr	r9,PVR
	rlwinm	r9,r9,16,16,31
	cmpi	0,r9,1
	beq	4f			/* not needed for 601 */
	mfspr	r11,HID0
	andi.	r0,r11,HID0_DCE
	ori	r11,r11,HID0_ICE|HID0_DCE
	ori	r8,r11,HID0_ICFI
	bne	3f			/* don't invalidate the D-cache */
	ori	r8,r8,HID0_DCI		/* unless it wasn't enabled */
3:
	sync
	mtspr	HID0,r8			/* enable and invalidate caches */
	sync
	mtspr	HID0,r11		/* enable caches */
	sync
	isync
	cmpi	0,r9,4			/* check for 604 */
	cmpi	1,r9,9			/* or 604e */
	cmpi	2,r9,10			/* or mach5 */
	cror	2,2,6
	cror	2,2,10
	bne	4f
	ori	r11,r11,HID0_SIED|HID0_BHTE /* for 604[e], enable */
	bne	2,5f
	ori	r11,r11,HID0_BTCD
5:	mtspr	HID0,r11		/* superscalar exec & br history tbl */
4:	blr

/*
 * Load stuff into the MMU.  Intended to be called with
 * IR=0 and DR=0.
 */
load_up_mmu:
	/* Load the SDR1 register (hash table base & size) */
	lis	r6,_SDR1@ha
	tophys(r6,r6)
#ifdef CONFIG_PPC64	
	ld	r6,_SDR1@l(r6)
	mtspr	SDR1,r6
	/* clear the v bit in the ASR so we can
	 * behave as if we have segment registers 
	 * -- Cort
	 */
	clrldi	r6,r6,63
	mtasr	r6
#else
	lwz	r6,_SDR1@l(r6)
	mtspr	SDR1,r6
#endif /* CONFIG_PPC64 */
	li	r0,16		/* load up segment register values */
	mtctr	r0		/* for context 0 */
	lis	r3,0x2000	/* Ku = 1, VSID = 0 */
	li	r4,0
3:	mtsrin	r3,r4
	addi	r3,r3,1		/* increment VSID */
	addis	r4,r4,0x1000	/* address of next segment */
	bdnz	3b
/* Load the BAT registers with the values set up by MMU_init.
   MMU_init takes care of whether we're on a 601 or not. */
	mfpvr	r3
	srwi	r3,r3,16
	cmpwi	r3,1
	lis	r3,BATS@ha
	addi	r3,r3,BATS@l
	tophys(r3,r3)
	LOAD_BAT(0,r3,r4,r5)
	LOAD_BAT(1,r3,r4,r5)
	LOAD_BAT(2,r3,r4,r5)
	LOAD_BAT(3,r3,r4,r5)
	blr

/*
 * This is where the main kernel code starts.
 */
start_here:
	bl	enable_caches

	/* ptr to current */
	lis	r2,init_task_union@h
	ori	r2,r2,init_task_union@l
	/* Clear out the BSS */
	lis	r11,_end@ha
	addi	r11,r11,_end@l
	lis	r8,__bss_start@ha
	addi	r8,r8,__bss_start@l
	subf	r11,r8,r11
	addi	r11,r11,3
	rlwinm.	r11,r11,30,2,31
	beq	2f
	addi	r8,r8,-4
	mtctr	r11
	li	r0,0
3:	stwu	r0,4(r8)
	bdnz	3b
2:
	/* stack */
	addi	r1,r2,TASK_UNION_SIZE
	li	r0,0
	stwu	r0,-STACK_FRAME_OVERHEAD(r1)
/*
 * Decide what sort of machine this is and initialize the MMU.
 */
	mr	r3,r31
	mr	r4,r30
	mr	r5,r29
	mr	r6,r28
	mr	r7,r27
	bl	identify_machine
	bl	MMU_init

/*
 * Go back to running unmapped so we can load up new values
 * for SDR1 (hash table pointer) and the segment registers
 * and change to using our exception vectors.
 */
	lis	r4,2f@h
	ori	r4,r4,2f@l
	tophys(r4,r4)
	li	r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
	mtspr	SRR0,r4
	mtspr	SRR1,r3
	rfi
/* Load up the kernel context */
2:
	SYNC			/* Force all PTE updates to finish */
	tlbia			/* Clear all TLB entries */
	sync			/* wait for tlbia/tlbie to finish */
#ifdef __SMP__
	tlbsync			/* ... on all CPUs */
	sync
#endif
	bl	load_up_mmu

/* Set up for using our exception vectors */
	/* ptr to phys current thread */
	tophys(r4,r2)
	addi	r4,r4,THREAD	/* init task's THREAD */
	mtspr	SPRG3,r4
	li	r3,0
	mtspr	SPRG2,r3	/* 0 => r1 has kernel sp */
/* Now turn on the MMU for real! */
	li	r4,MSR_KERNEL
	lis	r3,start_kernel@h
	ori	r3,r3,start_kernel@l
	mtspr	SRR0,r3
	mtspr	SRR1,r4
	rfi			/* enable MMU and jump to start_kernel */

/*
 * Set up the segment registers for a new context.
 */
_GLOBAL(set_context)
	rlwinm	r3,r3,4,8,27	/* VSID = context << 4 */
	addis	r3,r3,0x6000	/* Set Ks, Ku bits */
	li	r0,12		/* TASK_SIZE / SEGMENT_SIZE */
	mtctr	r0
	li	r4,0
3:	mtsrin	r3,r4
	addi	r3,r3,1		/* next VSID */
	addis	r4,r4,0x1000	/* address of next segment */
	bdnz	3b
	SYNC
	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
	.globl	sdata
sdata:
	.globl	empty_zero_page
empty_zero_page:
	.space	4096

	.globl	swapper_pg_dir
swapper_pg_dir:
	.space	4096	

/*
 * This space gets a copy of optional info passed to us by the bootstrap
 * Used to pass parameters into the kernel like root=/dev/sda1, etc.
 */	
	.globl	cmd_line
cmd_line:
	.space	512
	
/* 
 * An undocumented "feature" of 604e requires that the v bit
 * be cleared before changing BAT values.
 *
 * Also, newer IBM firmware does not clear bat3 and 4 so
 * this makes sure it's done.
 *  -- Cort 
 */
clear_bats:
	mfmsr	r20
	andi.	r19,r20,MSR_DR
	beqlr
	
	li	r20,0
	
	mtspr	DBAT0U,r20
	mtspr	DBAT0L,r20
	mtspr	IBAT0U,r20
	mtspr	IBAT0L,r20
	sync
	isync
	
	mtspr	DBAT1U,r20
	mtspr	DBAT1L,r20
	mtspr	IBAT1U,r20
	mtspr	IBAT1L,r20
	sync
	isync	

	mtspr	DBAT2U,r20
	mtspr	DBAT2L,r20
	mtspr	IBAT2U,r20
	mtspr	IBAT2L,r20
	
	mtspr	DBAT3U,r20
	mtspr	DBAT3L,r20
	mtspr	IBAT3U,r20
	mtspr	IBAT3L,r20
	
	blr