path: root/arch/powerpc/kernel/head_32.S

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *  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).
 *
 *  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.)
 */

#include <linux/init.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/cache.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/ptrace.h>
#include <asm/bug.h>
#include <asm/kvm_book3s_asm.h>
#include <asm/export.h>
#include <asm/feature-fixups.h>

#include "head_32.h"

/* 601 only have IBAT */
#ifdef CONFIG_PPC_BOOK3S_601
#define LOAD_BAT(n, reg, RA, RB)	\
	li	RA,0;			\
	mtspr	SPRN_IBAT##n##U,RA;	\
	lwz	RA,(n*16)+0(reg);	\
	lwz	RB,(n*16)+4(reg);	\
	mtspr	SPRN_IBAT##n##U,RA;	\
	mtspr	SPRN_IBAT##n##L,RB
#else
#define LOAD_BAT(n, reg, RA, RB)	\
	/* see the comment for clear_bats() -- Cort */ \
	li	RA,0;			\
	mtspr	SPRN_IBAT##n##U,RA;	\
	mtspr	SPRN_DBAT##n##U,RA;	\
	lwz	RA,(n*16)+0(reg);	\
	lwz	RB,(n*16)+4(reg);	\
	mtspr	SPRN_IBAT##n##U,RA;	\
	mtspr	SPRN_IBAT##n##L,RB;	\
	lwz	RA,(n*16)+8(reg);	\
	lwz	RB,(n*16)+12(reg);	\
	mtspr	SPRN_DBAT##n##U,RA;	\
	mtspr	SPRN_DBAT##n##L,RB
#endif

	__HEAD
	.stabs	"arch/powerpc/kernel/",N_SO,0,0,0f
	.stabs	"head_32.S",N_SO,0,0,0f
0:
_ENTRY(_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.
 */
_ENTRY(_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	/* used by __secondary_hold on prep (mtx) and chrp smp */
	nop	/* used by __secondary_hold on prep (mtx) and chrp smp */
	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
 *
 * 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:
/*
 * We have to do any OF calls before we map ourselves to KERNELBASE,
 * because OF may have I/O devices mapped into that area
 * (particularly on CHRP).
 */
	cmpwi	0,r5,0
	beq	1f

#ifdef CONFIG_PPC_OF_BOOT_TRAMPOLINE
	/* find out where we are now */
	bcl	20,31,$+4
0:	mflr	r8			/* r8 = runtime addr here */
	addis	r8,r8,(_stext - 0b)@ha
	addi	r8,r8,(_stext - 0b)@l	/* current runtime base addr */
	bl	prom_init
#endif /* CONFIG_PPC_OF_BOOT_TRAMPOLINE */

	/* We never return. We also hit that trap if trying to boot
	 * from OF while CONFIG_PPC_OF_BOOT_TRAMPOLINE isn't selected */
	trap

/*
 * Check for BootX signature when supporting PowerMac and branch to
 * appropriate trampoline if it's present
 */
#ifdef CONFIG_PPC_PMAC
1:	lis	r31,0x426f
	ori	r31,r31,0x6f58
	cmpw	0,r3,r31
	bne	1f
	bl	bootx_init
	trap
#endif /* CONFIG_PPC_PMAC */

1:	mr	r31,r3			/* save device tree ptr */
	li	r24,0			/* cpu # */

/*
 * early_init() does the early machine identification and does
 * the necessary low-level setup and clears the BSS
 *  -- Cort <cort@fsmlabs.com>
 */
	bl	early_init

/* Switch MMU off, clear BATs and flush TLB. At this point, r3 contains
 * the physical address we are running at, returned by early_init()
 */
 	bl	mmu_off
__after_mmu_off:
	bl	clear_bats
	bl	flush_tlbs

	bl	initial_bats
	bl	load_segment_registers
#ifdef CONFIG_KASAN
	bl	early_hash_table
#endif
#if defined(CONFIG_BOOTX_TEXT)
	bl	setup_disp_bat
#endif
#ifdef CONFIG_PPC_EARLY_DEBUG_CPM
	bl	setup_cpm_bat
#endif
#ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
	bl	setup_usbgecko_bat
#endif

/*
 * Call setup_cpu for CPU 0 and initialize 6xx Idle
 */
	bl	reloc_offset
	li	r24,0			/* cpu# */
	bl	call_setup_cpu		/* Call setup_cpu for this CPU */
#ifdef CONFIG_PPC_BOOK3S_32
	bl	reloc_offset
	bl	init_idle_6xx
#endif /* CONFIG_PPC_BOOK3S_32 */


/*
 * 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).
 * The MMU is off at this point.
 */
	bl	reloc_offset
	mr	r26,r3
	addis	r4,r3,KERNELBASE@h	/* current address of _start */
	lis	r5,PHYSICAL_START@h
	cmplw	0,r4,r5			/* already running at PHYSICAL_START? */
	bne	relocate_kernel
/*
 * 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
 * Actually no, pmac doesn't have it on any more. BootX enters with MMU
 * off, and in other cases, we now turn it off before changing BATs above.
 */
turn_on_mmu:
	mfmsr	r0
	ori	r0,r0,MSR_DR|MSR_IR|MSR_RI
	mtspr	SPRN_SRR1,r0
	lis	r0,start_here@h
	ori	r0,r0,start_here@l
	mtspr	SPRN_SRR0,r0
	SYNC
	RFI				/* enables MMU */

/*
 * We need __secondary_hold as a place to hold the other cpus on
 * an SMP machine, even when we are running a UP kernel.
 */
	. = 0xc0			/* for prep bootloader */
	li	r3,1			/* MTX only has 1 cpu */
	.globl	__secondary_hold
__secondary_hold:
	/* tell the master we're here */
	stw	r3,__secondary_hold_acknowledge@l(0)
#ifdef CONFIG_SMP
100:	lwz	r4,0(0)
	/* wait until we're told to start */
	cmpw	0,r4,r3
	bne	100b
	/* our cpu # was at addr 0 - go */
	mr	r24,r3			/* cpu # */
	b	__secondary_start
#else
	b	.
#endif /* CONFIG_SMP */

	.globl	__secondary_hold_spinloop
__secondary_hold_spinloop:
	.long	0
	.globl	__secondary_hold_acknowledge
__secondary_hold_acknowledge:
	.long	-1

/* System reset */
/* core99 pmac starts the seconary here by changing the vector, and
   putting it back to what it was (unknown_exception) when done.  */
	EXCEPTION(0x100, Reset, unknown_exception, EXC_XFER_STD)

/* Machine check */
/*
 * On CHRP, this is complicated by the fact that we could get a
 * machine check inside RTAS, and we have no guarantee that certain
 * critical registers will have the values we expect.  The set of
 * registers that might have bad values includes all the GPRs
 * and all the BATs.  We indicate that we are in RTAS by putting
 * a non-zero value, the address of the exception frame to use,
 * in thread.rtas_sp.  The machine check handler checks thread.rtas_sp
 * and uses its value if it is non-zero.
 * (Other exception handlers assume that r1 is a valid kernel stack
 * pointer when we take an exception from supervisor mode.)
 *	-- paulus.
 */
	. = 0x200
	DO_KVM  0x200
	EXCEPTION_PROLOG_0
#ifdef CONFIG_PPC_CHRP
	mfspr	r11, SPRN_SPRG_THREAD
	lwz	r11, RTAS_SP(r11)
	cmpwi	cr1, r11, 0
	bne	cr1, 7f
#endif /* CONFIG_PPC_CHRP */
	EXCEPTION_PROLOG_1
7:	EXCEPTION_PROLOG_2
	addi	r3,r1,STACK_FRAME_OVERHEAD
#ifdef CONFIG_PPC_CHRP
	bne	cr1,1f
#endif
	EXC_XFER_STD(0x200, machine_check_exception)
#ifdef CONFIG_PPC_CHRP
1:	b	machine_check_in_rtas
#endif

/* Data access exception. */
	. = 0x300
	DO_KVM  0x300
DataAccess:
	EXCEPTION_PROLOG
	mfspr	r10,SPRN_DSISR
	stw	r10,_DSISR(r11)
#ifdef CONFIG_PPC_KUAP
	andis.	r0,r10,(DSISR_BAD_FAULT_32S | DSISR_DABRMATCH | DSISR_PROTFAULT)@h
#else
	andis.	r0,r10,(DSISR_BAD_FAULT_32S|DSISR_DABRMATCH)@h
#endif
	bne	1f			/* if not, try to put a PTE */
	mfspr	r4,SPRN_DAR		/* into the hash table */
	rlwinm	r3,r10,32-15,21,21	/* DSISR_STORE -> _PAGE_RW */
BEGIN_MMU_FTR_SECTION
	bl	hash_page
END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
1:	lwz	r5,_DSISR(r11)		/* get DSISR value */
	mfspr	r4,SPRN_DAR
	stw	r4, _DAR(r11)
	EXC_XFER_LITE(0x300, handle_page_fault)


/* Instruction access exception. */
	. = 0x400
	DO_KVM  0x400
InstructionAccess:
	EXCEPTION_PROLOG
	andis.	r0,r9,SRR1_ISI_NOPT@h	/* no pte found? */
	beq	1f			/* if so, try to put a PTE */
	li	r3,0			/* into the hash table */
	mr	r4,r12			/* SRR0 is fault address */
BEGIN_MMU_FTR_SECTION
	bl	hash_page
END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
1:	mr	r4,r12
	andis.	r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
	stw	r4, _DAR(r11)
	EXC_XFER_LITE(0x400, handle_page_fault)

/* External interrupt */
	EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)

/* Alignment exception */
	. = 0x600
	DO_KVM  0x600
Alignment:
	EXCEPTION_PROLOG
	mfspr	r4,SPRN_DAR
	stw	r4,_DAR(r11)
	mfspr	r5,SPRN_DSISR
	stw	r5,_DSISR(r11)
	addi	r3,r1,STACK_FRAME_OVERHEAD
	EXC_XFER_STD(0x600, alignment_exception)

/* Program check exception */
	EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)

/* Floating-point unavailable */
	. = 0x800
	DO_KVM  0x800
FPUnavailable:
BEGIN_FTR_SECTION
/*
 * Certain Freescale cores don't have a FPU and treat fp instructions
 * as a FP Unavailable exception.  Redirect to illegal/emulation handling.
 */
	b 	ProgramCheck
END_FTR_SECTION_IFSET(CPU_FTR_FPU_UNAVAILABLE)
	EXCEPTION_PROLOG
	beq	1f
	bl	load_up_fpu		/* if from user, just load it up */
	b	fast_exception_return
1:	addi	r3,r1,STACK_FRAME_OVERHEAD
	EXC_XFER_LITE(0x800, kernel_fp_unavailable_exception)

/* Decrementer */
	EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)

	EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_STD)

/* System call */
	. = 0xc00
	DO_KVM  0xc00
SystemCall:
	SYSCALL_ENTRY	0xc00

/* Single step - not used on 601 */
	EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
	EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_STD)

/*
 * The Altivec unavailable trap is at 0x0f20.  Foo.
 * We effectively remap it to 0x3000.
 * We include an altivec unavailable exception vector even if
 * not configured for Altivec, so that you can't panic a
 * non-altivec kernel running on a machine with altivec just
 * by executing an altivec instruction.
 */
	. = 0xf00
	DO_KVM  0xf00
	b	PerformanceMonitor

	. = 0xf20
	DO_KVM  0xf20
	b	AltiVecUnavailable

/*
 * Handle TLB miss for instruction on 603/603e.
 * Note: we get an alternate set of r0 - r3 to use automatically.
 */
	. = 0x1000
InstructionTLBMiss:
/*
 * r0:	scratch
 * r1:	linux style pte ( later becomes ppc hardware pte )
 * r2:	ptr to linux-style pte
 * r3:	scratch
 */
	/* Get PTE (linux-style) and check access */
	mfspr	r3,SPRN_IMISS
#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC)
	lis	r1,PAGE_OFFSET@h		/* check if kernel address */
	cmplw	0,r1,r3
#endif
	mfspr	r2, SPRN_SPRG_PGDIR
#ifdef CONFIG_SWAP
	li	r1,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
#else
	li	r1,_PAGE_PRESENT | _PAGE_EXEC
#endif
#if defined(CONFIG_MODULES) || defined(CONFIG_DEBUG_PAGEALLOC)
	bge-	112f
	lis	r2, (swapper_pg_dir - PAGE_OFFSET)@ha	/* if kernel address, use */
	addi	r2, r2, (swapper_pg_dir - PAGE_OFFSET)@l	/* kernel page table */
#endif
112:	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 */
	rlwimi	r2,r3,22,20,29		/* insert next 10 bits of address */
	lwz	r0,0(r2)		/* get linux-style pte */
	andc.	r1,r1,r0		/* check access & ~permission */
	bne-	InstructionAddressInvalid /* return if access not permitted */
	/* Convert linux-style PTE to low word of PPC-style PTE */
	rlwimi	r0,r0,32-2,31,31	/* _PAGE_USER -> PP lsb */
	ori	r1, r1, 0xe06		/* clear out reserved bits */
	andc	r1, r0, r1		/* PP = user? 1 : 0 */
BEGIN_FTR_SECTION
	rlwinm	r1,r1,0,~_PAGE_COHERENT	/* clear M (coherence not required) */
END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
	mtspr	SPRN_RPA,r1
	tlbli	r3
	mfspr	r3,SPRN_SRR1		/* Need to restore CR0 */
	mtcrf	0x80,r3
	rfi
InstructionAddressInvalid:
	mfspr	r3,SPRN_SRR1
	rlwinm	r1,r3,9,6,6	/* Get load/store bit */

	addis	r1,r1,0x2000
	mtspr	SPRN_DSISR,r1	/* (shouldn't be needed) */
	andi.	r2,r3,0xFFFF	/* Clear upper bits of SRR1 */
	or	r2,r2,r1
	mtspr	SPRN_SRR1,r2
	mfspr	r1,SPRN_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	SPRN_DAR,r1	/* Set fault address */
	mfmsr	r0		/* Restore "normal" registers */
	xoris	r0,r0,MSR_TGPR>>16
	mtcrf	0x80,r3		/* Restore CR0 */
	mtmsr	r0
	b	InstructionAccess

/*
 * Handle TLB miss for DATA Load operation on 603/603e
 */
	. = 0x1100
DataLoadTLBMiss:
/*
 * r0:	scratch
 * r1:	linux style pte ( later becomes ppc hardware pte )
 * r2:	ptr to linux-style pte
 * r3:	scratch
 */
	/* Get PTE (linux-style) and check access */
	mfspr	r3,SPRN_DMISS
	lis	r1,PAGE_OFFSET@h		/* check if kernel address */
	cmplw	0,r1,r3
	mfspr	r2, SPRN_SPRG_PGDIR
#ifdef CONFIG_SWAP
	li	r1, _PAGE_PRESENT | _PAGE_ACCESSED
#else
	li	r1, _PAGE_PRESENT
#endif
	bge-	112f
	lis	r2, (swapper_pg_dir - PAGE_OFFSET)@ha	/* if kernel address, use */
	addi	r2, r2, (swapper_pg_dir - PAGE_OFFSET)@l	/* kernel page table */
112:	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 */
	rlwimi	r2,r3,22,20,29		/* insert next 10 bits of address */
	lwz	r0,0(r2)		/* get linux-style pte */
	andc.	r1,r1,r0		/* check access & ~permission */
	bne-	DataAddressInvalid	/* return if access not permitted */
	/*
	 * NOTE! We are assuming this is not an SMP system, otherwise
	 * we would need to update the pte atomically with lwarx/stwcx.
	 */
	/* Convert linux-style PTE to low word of PPC-style PTE */
	rlwinm	r1,r0,32-9,30,30	/* _PAGE_RW -> PP msb */
	rlwimi	r0,r0,32-1,30,30	/* _PAGE_USER -> PP msb */
	rlwimi	r0,r0,32-1,31,31	/* _PAGE_USER -> PP lsb */
	ori	r1,r1,0xe04		/* clear out reserved bits */
	andc	r1,r0,r1		/* PP = user? rw? 1: 3: 0 */
BEGIN_FTR_SECTION
	rlwinm	r1,r1,0,~_PAGE_COHERENT	/* clear M (coherence not required) */
END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
	mtspr	SPRN_RPA,r1
	mfspr	r2,SPRN_SRR1		/* Need to restore CR0 */
	mtcrf	0x80,r2
BEGIN_MMU_FTR_SECTION
	li	r0,1
	mfspr	r1,SPRN_SPRG_603_LRU
	rlwinm	r2,r3,20,27,31		/* Get Address bits 15:19 */
	slw	r0,r0,r2
	xor	r1,r0,r1
	srw	r0,r1,r2
	mtspr   SPRN_SPRG_603_LRU,r1
	mfspr	r2,SPRN_SRR1
	rlwimi	r2,r0,31-14,14,14
	mtspr   SPRN_SRR1,r2
END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
	tlbld	r3
	rfi
DataAddressInvalid:
	mfspr	r3,SPRN_SRR1
	rlwinm	r1,r3,9,6,6	/* Get load/store bit */
	addis	r1,r1,0x2000
	mtspr	SPRN_DSISR,r1
	andi.	r2,r3,0xFFFF	/* Clear upper bits of SRR1 */
	mtspr	SPRN_SRR1,r2
	mfspr	r1,SPRN_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	SPRN_DAR,r1	/* Set fault address */
	mfmsr	r0		/* Restore "normal" registers */
	xoris	r0,r0,MSR_TGPR>>16
	mtcrf	0x80,r3		/* Restore CR0 */
	mtmsr	r0
	b	DataAccess

/*
 * Handle TLB miss for DATA Store on 603/603e
 */
	. = 0x1200
DataStoreTLBMiss:
/*
 * r0:	scratch
 * r1:	linux style pte ( later becomes ppc hardware pte )
 * r2:	ptr to linux-style pte
 * r3:	scratch
 */
	/* Get PTE (linux-style) and check access */
	mfspr	r3,SPRN_DMISS
	lis	r1,PAGE_OFFSET@h		/* check if kernel address */
	cmplw	0,r1,r3
	mfspr	r2, SPRN_SPRG_PGDIR
#ifdef CONFIG_SWAP
	li	r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT | _PAGE_ACCESSED
#else
	li	r1, _PAGE_RW | _PAGE_DIRTY | _PAGE_PRESENT
#endif
	bge-	112f
	lis	r2, (swapper_pg_dir - PAGE_OFFSET)@ha	/* if kernel address, use */
	addi	r2, r2, (swapper_pg_dir - PAGE_OFFSET)@l	/* kernel page table */
112:	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 */
	rlwimi	r2,r3,22,20,29		/* insert next 10 bits of address */
	lwz	r0,0(r2)		/* get linux-style pte */
	andc.	r1,r1,r0		/* check access & ~permission */
	bne-	DataAddressInvalid	/* return if access not permitted */
	/*
	 * NOTE! We are assuming this is not an SMP system, otherwise
	 * we would need to update the pte atomically with lwarx/stwcx.
	 */
	/* Convert linux-style PTE to low word of PPC-style PTE */
	rlwimi	r0,r0,32-2,31,31	/* _PAGE_USER -> PP lsb */
	li	r1,0xe06		/* clear out reserved bits & PP msb */
	andc	r1,r0,r1		/* PP = user? 1: 0 */
BEGIN_FTR_SECTION
	rlwinm	r1,r1,0,~_PAGE_COHERENT	/* clear M (coherence not required) */
END_FTR_SECTION_IFCLR(CPU_FTR_NEED_COHERENT)
	mtspr	SPRN_RPA,r1
	mfspr	r2,SPRN_SRR1		/* Need to restore CR0 */
	mtcrf	0x80,r2
BEGIN_MMU_FTR_SECTION
	li	r0,1
	mfspr	r1,SPRN_SPRG_603_LRU
	rlwinm	r2,r3,20,27,31		/* Get Address bits 15:19 */
	slw	r0,r0,r2
	xor	r1,r0,r1
	srw	r0,r1,r2
	mtspr   SPRN_SPRG_603_LRU,r1
	mfspr	r2,SPRN_SRR1
	rlwimi	r2,r0,31-14,14,14
	mtspr   SPRN_SRR1,r2
END_MMU_FTR_SECTION_IFSET(MMU_FTR_NEED_DTLB_SW_LRU)
	tlbld	r3
	rfi

#ifndef CONFIG_ALTIVEC
#define altivec_assist_exception	unknown_exception
#endif

	EXCEPTION(0x1300, Trap_13, instruction_breakpoint_exception, EXC_XFER_STD)
	EXCEPTION(0x1400, SMI, SMIException, EXC_XFER_STD)
	EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1600, Trap_16, altivec_assist_exception, EXC_XFER_STD)
	EXCEPTION(0x1700, Trap_17, TAUException, EXC_XFER_STD)
	EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1c00, Trap_1c, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2000, RunMode, RunModeException, EXC_XFER_STD)
	EXCEPTION(0x2100, Trap_21, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2200, Trap_22, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2300, Trap_23, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2400, Trap_24, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2500, Trap_25, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2600, Trap_26, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2700, Trap_27, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2800, Trap_28, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2900, Trap_29, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2a00, Trap_2a, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2b00, Trap_2b, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2c00, Trap_2c, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2d00, Trap_2d, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2e00, Trap_2e, unknown_exception, EXC_XFER_STD)
	EXCEPTION(0x2f00, Trap_2f, unknown_exception, EXC_XFER_STD)

	. = 0x3000

AltiVecUnavailable:
	EXCEPTION_PROLOG
#ifdef CONFIG_ALTIVEC
	beq	1f
	bl	load_up_altivec		/* if from user, just load it up */
	b	fast_exception_return
#endif /* CONFIG_ALTIVEC */
1:	addi	r3,r1,STACK_FRAME_OVERHEAD
	EXC_XFER_LITE(0xf20, altivec_unavailable_exception)

PerformanceMonitor:
	EXCEPTION_PROLOG
	addi	r3,r1,STACK_FRAME_OVERHEAD
	EXC_XFER_STD(0xf00, performance_monitor_exception)


/*
 * This code is jumped to from the startup code to copy
 * the kernel image to physical address PHYSICAL_START.
 */
relocate_kernel:
	addis	r9,r26,klimit@ha	/* fetch klimit */
	lwz	r25,klimit@l(r9)
	addis	r25,r25,-KERNELBASE@h
	lis	r3,PHYSICAL_START@h	/* Destination base address */
	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.
 */
_ENTRY(copy_and_flush)
	addi	r5,r5,-4
	addi	r6,r6,-4
4:	li	r0,L1_CACHE_BYTES/4
	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
	sync				/* additional sync needed on g4 */
	isync
	addi	r5,r5,4
	addi	r6,r6,4
	blr

#ifdef CONFIG_SMP
	.globl __secondary_start_mpc86xx
__secondary_start_mpc86xx:
	mfspr	r3, SPRN_PIR
	stw	r3, __secondary_hold_acknowledge@l(0)
	mr	r24, r3			/* cpu # */
	b	__secondary_start

	.globl	__secondary_start_pmac_0
__secondary_start_pmac_0:
	/* NB the entries for cpus 0, 1, 2 must each occupy 8 bytes. */
	li	r24,0
	b	1f
	li	r24,1
	b	1f
	li	r24,2
	b	1f
	li	r24,3
1:
	/* on powersurge, 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:
	/* Copy some CPU settings from CPU 0 */
	bl	__restore_cpu_setup

	lis	r3,-KERNELBASE@h
	mr	r4,r24
	bl	call_setup_cpu		/* Call setup_cpu for this CPU */
#ifdef CONFIG_PPC_BOOK3S_32
	lis	r3,-KERNELBASE@h
	bl	init_idle_6xx
#endif /* CONFIG_PPC_BOOK3S_32 */

	/* get current's stack and current */
	lis	r2,secondary_current@ha
	tophys(r2,r2)
	lwz	r2,secondary_current@l(r2)
	tophys(r1,r2)
	lwz	r1,TASK_STACK(r1)

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

	/* load up the MMU */
	bl	load_segment_registers
	bl	load_up_mmu

	/* ptr to phys current thread */
	tophys(r4,r2)
	addi	r4,r4,THREAD	/* phys address of our thread_struct */
	mtspr	SPRN_SPRG_THREAD,r4
	lis	r4, (swapper_pg_dir - PAGE_OFFSET)@h
	ori	r4, r4, (swapper_pg_dir - PAGE_OFFSET)@l
	mtspr	SPRN_SPRG_PGDIR, r4

	/* enable MMU and jump to start_secondary */
	li	r4,MSR_KERNEL
	lis	r3,start_secondary@h
	ori	r3,r3,start_secondary@l
	mtspr	SPRN_SRR0,r3
	mtspr	SPRN_SRR1,r4
	SYNC
	RFI
#endif /* CONFIG_SMP */

#ifdef CONFIG_KVM_BOOK3S_HANDLER
#include "../kvm/book3s_rmhandlers.S"
#endif

/*
 * Those generic dummy functions are kept for CPUs not
 * included in CONFIG_PPC_BOOK3S_32
 */
#if !defined(CONFIG_PPC_BOOK3S_32)
_ENTRY(__save_cpu_setup)
	blr
_ENTRY(__restore_cpu_setup)
	blr
#endif /* !defined(CONFIG_PPC_BOOK3S_32) */

/*
 * Load stuff into the MMU.  Intended to be called with
 * IR=0 and DR=0.
 */
#ifdef CONFIG_KASAN
early_hash_table:
	sync			/* Force all PTE updates to finish */
	isync
	tlbia			/* Clear all TLB entries */
	sync			/* wait for tlbia/tlbie to finish */
	TLBSYNC			/* ... on all CPUs */
	/* Load the SDR1 register (hash table base & size) */
	lis	r6, early_hash - PAGE_OFFSET@h
	ori	r6, r6, 3	/* 256kB table */
	mtspr	SPRN_SDR1, r6
	blr
#endif

load_up_mmu:
	sync			/* Force all PTE updates to finish */
	isync
	tlbia			/* Clear all TLB entries */
	sync			/* wait for tlbia/tlbie to finish */
	TLBSYNC			/* ... on all CPUs */
	/* Load the SDR1 register (hash table base & size) */
	lis	r6,_SDR1@ha
	tophys(r6,r6)
	lwz	r6,_SDR1@l(r6)
	mtspr	SPRN_SDR1,r6

/* 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. */
	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)
BEGIN_MMU_FTR_SECTION
	LOAD_BAT(4,r3,r4,r5)
	LOAD_BAT(5,r3,r4,r5)
	LOAD_BAT(6,r3,r4,r5)
	LOAD_BAT(7,r3,r4,r5)
END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_HIGH_BATS)
	blr

load_segment_registers:
	li	r0, NUM_USER_SEGMENTS /* load up user segment register values */
	mtctr	r0		/* for context 0 */
	li	r3, 0		/* Kp = 0, Ks = 0, VSID = 0 */
#ifdef CONFIG_PPC_KUEP
	oris	r3, r3, SR_NX@h	/* Set Nx */
#endif
#ifdef CONFIG_PPC_KUAP
	oris	r3, r3, SR_KS@h	/* Set Ks */
#endif
	li	r4, 0
3:	mtsrin	r3, r4
	addi	r3, r3, 0x111	/* increment VSID */
	addis	r4, r4, 0x1000	/* address of next segment */
	bdnz	3b
	li	r0, 16 - NUM_USER_SEGMENTS /* load up kernel segment registers */
	mtctr	r0			/* for context 0 */
	rlwinm	r3, r3, 0, ~SR_NX	/* Nx = 0 */
	rlwinm	r3, r3, 0, ~SR_KS	/* Ks = 0 */
	oris	r3, r3, SR_KP@h		/* Kp = 1 */
3:	mtsrin	r3, r4
	addi	r3, r3, 0x111	/* increment VSID */
	addis	r4, r4, 0x1000	/* address of next segment */
	bdnz	3b
	blr

/*
 * This is where the main kernel code starts.
 */
start_here:
	/* ptr to current */
	lis	r2,init_task@h
	ori	r2,r2,init_task@l
	/* Set up for using our exception vectors */
	/* ptr to phys current thread */
	tophys(r4,r2)
	addi	r4,r4,THREAD	/* init task's THREAD */
	mtspr	SPRN_SPRG_THREAD,r4
	lis	r4, (swapper_pg_dir - PAGE_OFFSET)@h
	ori	r4, r4, (swapper_pg_dir - PAGE_OFFSET)@l
	mtspr	SPRN_SPRG_PGDIR, 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)
/*
 * Do early platform-specific initialization,
 * and set up the MMU.
 */
#ifdef CONFIG_KASAN
	bl	kasan_early_init
#endif
	li	r3,0
	mr	r4,r31
	bl	machine_init
	bl	__save_cpu_setup
	bl	MMU_init
#ifdef CONFIG_KASAN
BEGIN_MMU_FTR_SECTION
	bl	MMU_init_hw_patch
END_MMU_FTR_SECTION_IFSET(MMU_FTR_HPTE_TABLE)
#endif

/*
 * 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	SPRN_SRR0,r4
	mtspr	SPRN_SRR1,r3
	SYNC
	RFI
/* Load up the kernel context */
2:	bl	load_up_mmu

#ifdef CONFIG_BDI_SWITCH
	/* Add helper information for the Abatron bdiGDB debugger.
	 * We do this here because we know the mmu is disabled, and
	 * will be enabled for real in just a few instructions.
	 */
	lis	r5, abatron_pteptrs@h
	ori	r5, r5, abatron_pteptrs@l
	stw	r5, 0xf0(r0)	/* This much match your Abatron config */
	lis	r6, swapper_pg_dir@h
	ori	r6, r6, swapper_pg_dir@l
	tophys(r5, r5)
	stw	r6, 0(r5)
#endif /* CONFIG_BDI_SWITCH */

/* Now turn on the MMU for real! */
	li	r4,MSR_KERNEL
	lis	r3,start_kernel@h
	ori	r3,r3,start_kernel@l
	mtspr	SPRN_SRR0,r3
	mtspr	SPRN_SRR1,r4
	SYNC
	RFI

/*
 * void switch_mmu_context(struct mm_struct *prev, struct mm_struct *next);
 *
 * Set up the segment registers for a new context.
 */
_ENTRY(switch_mmu_context)
	lwz	r3,MMCONTEXTID(r4)
	cmpwi	cr0,r3,0
	blt-	4f
	mulli	r3,r3,897	/* multiply context by skew factor */
	rlwinm	r3,r3,4,8,27	/* VSID = (context & 0xfffff) << 4 */
#ifdef CONFIG_PPC_KUEP
	oris	r3, r3, SR_NX@h	/* Set Nx */
#endif
#ifdef CONFIG_PPC_KUAP
	oris	r3, r3, SR_KS@h	/* Set Ks */
#endif
	li	r0,NUM_USER_SEGMENTS
	mtctr	r0

	lwz	r4, MM_PGD(r4)
#ifdef CONFIG_BDI_SWITCH
	/* Context switch the PTE pointer for the Abatron BDI2000.
	 * The PGDIR is passed as second argument.
	 */
	lis	r5, abatron_pteptrs@ha
	stw	r4, abatron_pteptrs@l + 0x4(r5)
#endif
	tophys(r4, r4)
	mtspr	SPRN_SPRG_PGDIR, r4
	li	r4,0
	isync
3:
	mtsrin	r3,r4
	addi	r3,r3,0x111	/* next VSID */
	rlwinm	r3,r3,0,8,3	/* clear out any overflow from VSID field */
	addis	r4,r4,0x1000	/* address of next segment */
	bdnz	3b
	sync
	isync
	blr
4:	trap
	EMIT_BUG_ENTRY 4b,__FILE__,__LINE__,0
	blr
EXPORT_SYMBOL(switch_mmu_context)

/*
 * 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:
	li	r10,0

#ifndef CONFIG_PPC_BOOK3S_601
	mtspr	SPRN_DBAT0U,r10
	mtspr	SPRN_DBAT0L,r10
	mtspr	SPRN_DBAT1U,r10
	mtspr	SPRN_DBAT1L,r10
	mtspr	SPRN_DBAT2U,r10
	mtspr	SPRN_DBAT2L,r10
	mtspr	SPRN_DBAT3U,r10
	mtspr	SPRN_DBAT3L,r10
#endif
	mtspr	SPRN_IBAT0U,r10
	mtspr	SPRN_IBAT0L,r10
	mtspr	SPRN_IBAT1U,r10
	mtspr	SPRN_IBAT1L,r10
	mtspr	SPRN_IBAT2U,r10
	mtspr	SPRN_IBAT2L,r10
	mtspr	SPRN_IBAT3U,r10
	mtspr	SPRN_IBAT3L,r10
BEGIN_MMU_FTR_SECTION
	/* Here's a tweak: at this point, CPU setup have
	 * not been called yet, so HIGH_BAT_EN may not be
	 * set in HID0 for the 745x processors. However, it
	 * seems that doesn't affect our ability to actually
	 * write to these SPRs.
	 */
	mtspr	SPRN_DBAT4U,r10
	mtspr	SPRN_DBAT4L,r10
	mtspr	SPRN_DBAT5U,r10
	mtspr	SPRN_DBAT5L,r10
	mtspr	SPRN_DBAT6U,r10
	mtspr	SPRN_DBAT6L,r10
	mtspr	SPRN_DBAT7U,r10
	mtspr	SPRN_DBAT7L,r10
	mtspr	SPRN_IBAT4U,r10
	mtspr	SPRN_IBAT4L,r10
	mtspr	SPRN_IBAT5U,r10
	mtspr	SPRN_IBAT5L,r10
	mtspr	SPRN_IBAT6U,r10
	mtspr	SPRN_IBAT6L,r10
	mtspr	SPRN_IBAT7U,r10
	mtspr	SPRN_IBAT7L,r10
END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_HIGH_BATS)
	blr

_ENTRY(update_bats)
	lis	r4, 1f@h
	ori	r4, r4, 1f@l
	tophys(r4, r4)
	mfmsr	r6
	mflr	r7
	li	r3, MSR_KERNEL & ~(MSR_IR | MSR_DR)
	rlwinm	r0, r6, 0, ~MSR_RI
	rlwinm	r0, r0, 0, ~MSR_EE
	mtmsr	r0
	mtspr	SPRN_SRR0, r4
	mtspr	SPRN_SRR1, r3
	SYNC
	RFI
1:	bl	clear_bats
	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)
BEGIN_MMU_FTR_SECTION
	LOAD_BAT(4, r3, r4, r5)
	LOAD_BAT(5, r3, r4, r5)
	LOAD_BAT(6, r3, r4, r5)
	LOAD_BAT(7, r3, r4, r5)
END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_HIGH_BATS)
	li	r3, MSR_KERNEL & ~(MSR_IR | MSR_DR | MSR_RI)
	mtmsr	r3
	mtspr	SPRN_SRR0, r7
	mtspr	SPRN_SRR1, r6
	SYNC
	RFI

flush_tlbs:
	lis	r10, 0x40
1:	addic.	r10, r10, -0x1000
	tlbie	r10
	bgt	1b
	sync
	blr

mmu_off:
 	addi	r4, r3, __after_mmu_off - _start
	mfmsr	r3
	andi.	r0,r3,MSR_DR|MSR_IR		/* MMU enabled? */
	beqlr
	andc	r3,r3,r0
	mtspr	SPRN_SRR0,r4
	mtspr	SPRN_SRR1,r3
	sync
	RFI

/*
 * On 601, we use 3 BATs to map up to 24M of RAM at _PAGE_OFFSET
 * (we keep one for debugging) and on others, we use one 256M BAT.
 */
initial_bats:
	lis	r11,PAGE_OFFSET@h
#ifdef CONFIG_PPC_BOOK3S_601
	ori	r11,r11,4		/* set up BAT registers for 601 */
	li	r8,0x7f			/* valid, block length = 8MB */
	mtspr	SPRN_IBAT0U,r11		/* N.B. 601 has valid bit in */
	mtspr	SPRN_IBAT0L,r8		/* lower BAT register */
	addis	r11,r11,0x800000@h
	addis	r8,r8,0x800000@h
	mtspr	SPRN_IBAT1U,r11
	mtspr	SPRN_IBAT1L,r8
	addis	r11,r11,0x800000@h
	addis	r8,r8,0x800000@h
	mtspr	SPRN_IBAT2U,r11
	mtspr	SPRN_IBAT2L,r8
#else
	tophys(r8,r11)
#ifdef CONFIG_SMP
	ori	r8,r8,0x12		/* R/W access, M=1 */
#else
	ori	r8,r8,2			/* R/W access */
#endif /* CONFIG_SMP */
	ori	r11,r11,BL_256M<<2|0x2	/* set up BAT registers for 604 */

	mtspr	SPRN_DBAT0L,r8		/* N.B. 6xx (not 601) have valid */
	mtspr	SPRN_DBAT0U,r11		/* bit in upper BAT register */
	mtspr	SPRN_IBAT0L,r8
	mtspr	SPRN_IBAT0U,r11
#endif
	isync
	blr

#ifdef CONFIG_BOOTX_TEXT
setup_disp_bat:
	/*
	 * setup the display bat prepared for us in prom.c
	 */
	mflr	r8
	bl	reloc_offset
	mtlr	r8
	addis	r8,r3,disp_BAT@ha
	addi	r8,r8,disp_BAT@l
	cmpwi	cr0,r8,0
	beqlr
	lwz	r11,0(r8)
	lwz	r8,4(r8)
#ifndef CONFIG_PPC_BOOK3S_601
	mtspr	SPRN_DBAT3L,r8
	mtspr	SPRN_DBAT3U,r11
#else
	mtspr	SPRN_IBAT3L,r8
	mtspr	SPRN_IBAT3U,r11
#endif
	blr
#endif /* CONFIG_BOOTX_TEXT */

#ifdef CONFIG_PPC_EARLY_DEBUG_CPM
setup_cpm_bat:
	lis	r8, 0xf000
	ori	r8, r8,	0x002a
	mtspr	SPRN_DBAT1L, r8

	lis	r11, 0xf000
	ori	r11, r11, (BL_1M << 2) | 2
	mtspr	SPRN_DBAT1U, r11

	blr
#endif

#ifdef CONFIG_PPC_EARLY_DEBUG_USBGECKO
setup_usbgecko_bat:
	/* prepare a BAT for early io */
#if defined(CONFIG_GAMECUBE)
	lis	r8, 0x0c00
#elif defined(CONFIG_WII)
	lis	r8, 0x0d00
#else
#error Invalid platform for USB Gecko based early debugging.
#endif
	/*
	 * The virtual address used must match the virtual address
	 * associated to the fixmap entry FIX_EARLY_DEBUG_BASE.
	 */
	lis	r11, 0xfffe	/* top 128K */
	ori	r8, r8, 0x002a	/* uncached, guarded ,rw */
	ori	r11, r11, 0x2	/* 128K, Vs=1, Vp=0 */
	mtspr	SPRN_DBAT1L, r8
	mtspr	SPRN_DBAT1U, r11
	blr
#endif

#ifdef CONFIG_8260
/* Jump into the system reset for the rom.
 * We first disable the MMU, and then jump to the ROM reset address.
 *
 * r3 is the board info structure, r4 is the location for starting.
 * I use this for building a small kernel that can load other kernels,
 * rather than trying to write or rely on a rom monitor that can tftp load.
 */
       .globl  m8260_gorom
m8260_gorom:
	mfmsr	r0
	rlwinm	r0,r0,0,17,15	/* clear MSR_EE in r0 */
	sync
	mtmsr	r0
	sync
	mfspr	r11, SPRN_HID0
	lis	r10, 0
	ori	r10,r10,HID0_ICE|HID0_DCE
	andc	r11, r11, r10
	mtspr	SPRN_HID0, r11
	isync
	li	r5, MSR_ME|MSR_RI
	lis	r6,2f@h
	addis	r6,r6,-KERNELBASE@h
	ori	r6,r6,2f@l
	mtspr	SPRN_SRR0,r6
	mtspr	SPRN_SRR1,r5
	isync
	sync
	rfi
2:
	mtlr	r4
	blr
#endif


/*
 * 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
EXPORT_SYMBOL(empty_zero_page)

	.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