/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Kernel execution entry point code.
 *
 *    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
 *    Copyright 2002-2005 MontaVista Software, Inc.
 *      PowerPC 44x support, Matt Porter <mporter@kernel.crashing.org>
 */

#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>
#include <asm/synch.h>
#include <asm/export.h>
#include <asm/code-patching-asm.h>
#include "head_booke.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=128")
 *   r7 - End of kernel command line string
 *
 */
        __HEAD
_ENTRY(_stext);
_ENTRY(_start);
        /*
         * Reserve a word at a fixed location to store the address
         * of abatron_pteptrs
         */
        nop
        mr      r31,r3          /* save device tree ptr */
        li      r24,0           /* CPU number */

#ifdef CONFIG_RELOCATABLE
/*
 * Relocate ourselves to the current runtime address.
 * This is called only by the Boot CPU.
 * "relocate" is called with our current runtime virutal
 * address.
 * r21 will be loaded with the physical runtime address of _stext
 */
        bl      0f                              /* Get our runtime address */
0:      mflr    r21                             /* Make it accessible */
        addis   r21,r21,(_stext - 0b)@ha
        addi    r21,r21,(_stext - 0b)@l         /* Get our current runtime base */

        /*
         * We have the runtime (virutal) address of our base.
         * We calculate our shift of offset from a 256M page.
         * We could map the 256M page we belong to at PAGE_OFFSET and
         * get going from there.
         */
        lis     r4,KERNELBASE@h
        ori     r4,r4,KERNELBASE@l
        rlwinm  r6,r21,0,4,31                   /* r6 = PHYS_START % 256M */
        rlwinm  r5,r4,0,4,31                    /* r5 = KERNELBASE % 256M */
        subf    r3,r5,r6                        /* r3 = r6 - r5 */
        add     r3,r4,r3                        /* Required Virutal Address */

        bl      relocate
#endif

        bl      init_cpu_state

        /*
         * This is where the main kernel code starts.
         */

        /* ptr to current */
        lis     r2,init_task@h
        ori     r2,r2,init_task@l

        /* ptr to current thread */
        addi    r4,r2,THREAD    /* init task's THREAD */
        mtspr   SPRN_SPRG_THREAD,r4

        /* stack */
        lis     r1,init_thread_union@h
        ori     r1,r1,init_thread_union@l
        li      r0,0
        stwu    r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)

        bl      early_init

#ifdef CONFIG_RELOCATABLE
        /*
         * Relocatable kernel support based on processing of dynamic
         * relocation entries.
         *
         * r25 will contain RPN/ERPN for the start address of memory
         * r21 will contain the current offset of _stext
         */
        lis     r3,kernstart_addr@ha
        la      r3,kernstart_addr@l(r3)

        /*
         * Compute the kernstart_addr.
         * kernstart_addr => (r6,r8)
         * kernstart_addr & ~0xfffffff => (r6,r7)
         */
        rlwinm  r6,r25,0,28,31  /* ERPN. Bits 32-35 of Address */
        rlwinm  r7,r25,0,0,3    /* RPN - assuming 256 MB page size */
        rlwinm  r8,r21,0,4,31   /* r8 = (_stext & 0xfffffff) */
        or      r8,r7,r8        /* Compute the lower 32bit of kernstart_addr */

        /* Store kernstart_addr */
        stw     r6,0(r3)        /* higher 32bit */
        stw     r8,4(r3)        /* lower 32bit  */

        /*
         * Compute the virt_phys_offset :
         * virt_phys_offset = stext.run - kernstart_addr
         *
         * stext.run = (KERNELBASE & ~0xfffffff) + (kernstart_addr & 0xfffffff)
         * When we relocate, we have :
         *
         *      (kernstart_addr & 0xfffffff) = (stext.run & 0xfffffff)
         *
         * hence:
         *  virt_phys_offset = (KERNELBASE & ~0xfffffff) - (kernstart_addr & ~0xfffffff)
         *
         */

        /* KERNELBASE&~0xfffffff => (r4,r5) */
        li      r4, 0           /* higer 32bit */
        lis     r5,KERNELBASE@h
        rlwinm  r5,r5,0,0,3     /* Align to 256M, lower 32bit */

        /*
         * 64bit subtraction.
         */
        subfc   r5,r7,r5
        subfe   r4,r6,r4

        /* Store virt_phys_offset */
        lis     r3,virt_phys_offset@ha
        la      r3,virt_phys_offset@l(r3)

        stw     r4,0(r3)
        stw     r5,4(r3)

#elif defined(CONFIG_DYNAMIC_MEMSTART)
        /*
         * Mapping based, page aligned dynamic kernel loading.
         *
         * r25 will contain RPN/ERPN for the start address of memory
         *
         * Add the difference between KERNELBASE and PAGE_OFFSET to the
         * start of physical memory to get kernstart_addr.
         */
        lis     r3,kernstart_addr@ha
        la      r3,kernstart_addr@l(r3)

        lis     r4,KERNELBASE@h
        ori     r4,r4,KERNELBASE@l
        lis     r5,PAGE_OFFSET@h
        ori     r5,r5,PAGE_OFFSET@l
        subf    r4,r5,r4

        rlwinm  r6,r25,0,28,31  /* ERPN */
        rlwinm  r7,r25,0,0,3    /* RPN - assuming 256 MB page size */
        add     r7,r7,r4

        stw     r6,0(r3)
        stw     r7,4(r3)
#endif

/*
 * Decide what sort of machine this is and initialize the MMU.
 */
#ifdef CONFIG_KASAN
        bl      kasan_early_init
#endif
        li      r3,0
        mr      r4,r31
        bl      machine_init
        bl      MMU_init

        /* Setup 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
        lis     r4, KERNELBASE@h
        ori     r4, r4, KERNELBASE@l
        stw     r5, 0(r4)       /* Save abatron_pteptrs at a fixed location */
        stw     r6, 0(r5)

        /* Clear the Machine Check Syndrome Register */
        li      r0,0
        mtspr   SPRN_MCSR,r0

        /* Let's move on */
        lis     r4,start_kernel@h
        ori     r4,r4,start_kernel@l
        lis     r3,MSR_KERNEL@h
        ori     r3,r3,MSR_KERNEL@l
        mtspr   SPRN_SRR0,r4
        mtspr   SPRN_SRR1,r3
        rfi                     /* change context and jump to start_kernel */

/*
 * Interrupt vector entry code
 *
 * The Book E MMUs are always on so we don't need to handle
 * interrupts in real mode as with previous PPC processors. In
 * this case we handle interrupts in the kernel virtual address
 * space.
 *
 * Interrupt vectors are dynamically placed relative to the
 * interrupt prefix as determined by the address of interrupt_base.
 * The interrupt vectors offsets are programmed using the labels
 * for each interrupt vector entry.
 *
 * Interrupt vectors must be aligned on a 16 byte boundary.
 * We align on a 32 byte cache line boundary for good measure.
 */

interrupt_base:
        /* Critical Input Interrupt */
        CRITICAL_EXCEPTION(0x0100, CRITICAL, CriticalInput, unknown_exception)

        /* Machine Check Interrupt */
        CRITICAL_EXCEPTION(0x0200, MACHINE_CHECK, MachineCheck, \
                           machine_check_exception)
        MCHECK_EXCEPTION(0x0210, MachineCheckA, machine_check_exception)

        /* Data Storage Interrupt */
        DATA_STORAGE_EXCEPTION

                /* Instruction Storage Interrupt */
        INSTRUCTION_STORAGE_EXCEPTION

        /* External Input Interrupt */
        EXCEPTION(0x0500, BOOKE_INTERRUPT_EXTERNAL, ExternalInput, \
                  do_IRQ, EXC_XFER_LITE)

        /* Alignment Interrupt */
        ALIGNMENT_EXCEPTION

        /* Program Interrupt */
        PROGRAM_EXCEPTION

        /* Floating Point Unavailable Interrupt */
#ifdef CONFIG_PPC_FPU
        FP_UNAVAILABLE_EXCEPTION
#else
        EXCEPTION(0x2010, BOOKE_INTERRUPT_FP_UNAVAIL, \
                  FloatingPointUnavailable, unknown_exception, EXC_XFER_STD)
#endif
        /* System Call Interrupt */
        START_EXCEPTION(SystemCall)
        SYSCALL_ENTRY   0xc00 BOOKE_INTERRUPT_SYSCALL

        /* Auxiliary Processor Unavailable Interrupt */
        EXCEPTION(0x2020, BOOKE_INTERRUPT_AP_UNAVAIL, \
                  AuxillaryProcessorUnavailable, unknown_exception, EXC_XFER_STD)

        /* Decrementer Interrupt */
        DECREMENTER_EXCEPTION

        /* Fixed Internal Timer Interrupt */
        /* TODO: Add FIT support */
        EXCEPTION(0x1010, BOOKE_INTERRUPT_FIT, FixedIntervalTimer, \
                  unknown_exception, EXC_XFER_STD)

        /* Watchdog Timer Interrupt */
        /* TODO: Add watchdog support */
#ifdef CONFIG_BOOKE_WDT
        CRITICAL_EXCEPTION(0x1020, WATCHDOG, WatchdogTimer, WatchdogException)
#else
        CRITICAL_EXCEPTION(0x1020, WATCHDOG, WatchdogTimer, unknown_exception)
#endif

        /* Data TLB Error Interrupt */
        START_EXCEPTION(DataTLBError44x)
        mtspr   SPRN_SPRG_WSCRATCH0, r10                /* Save some working registers */
        mtspr   SPRN_SPRG_WSCRATCH1, r11
        mtspr   SPRN_SPRG_WSCRATCH2, r12
        mtspr   SPRN_SPRG_WSCRATCH3, r13
        mfcr    r11
        mtspr   SPRN_SPRG_WSCRATCH4, r11
        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

        mfspr   r12,SPRN_MMUCR
        rlwinm  r12,r12,0,0,23          /* Clear TID */

        b       4f

        /* Get the PGD for the current thread */
3:
        mfspr   r11,SPRN_SPRG_THREAD
        lwz     r11,PGDIR(r11)

        /* Load PID into MMUCR TID */
        mfspr   r12,SPRN_MMUCR
        mfspr   r13,SPRN_PID            /* Get PID */
        rlwimi  r12,r13,0,24,31         /* Set TID */

4:
        mtspr   SPRN_MMUCR,r12

        /* Mask of required permission bits. Note that while we
         * do copy ESR:ST to _PAGE_RW position as trying to write
         * to an RO page is pretty common, we don't do it with
         * _PAGE_DIRTY. We could do it, but it's a fairly rare
         * event so I'd rather take the overhead when it happens
         * rather than adding an instruction here. We should measure
         * whether the whole thing is worth it in the first place
         * as we could avoid loading SPRN_ESR completely in the first
         * place...
         *
         * TODO: Is it worth doing that mfspr & rlwimi in the first
         *       place or can we save a couple of instructions here ?
         */
        mfspr   r12,SPRN_ESR
        li      r13,_PAGE_PRESENT|_PAGE_ACCESSED
        rlwimi  r13,r12,10,30,30

        /* Load the PTE */
        /* Compute pgdir/pmd offset */
        rlwinm  r12, r10, PPC44x_PGD_OFF_SHIFT, PPC44x_PGD_OFF_MASK_BIT, 29
        lwzx    r11, r12, r11           /* Get pgd/pmd entry */
        rlwinm. r12, r11, 0, 0, 20      /* Extract pt base address */
        beq     2f                      /* Bail if no table */

        /* Compute pte address */
        rlwimi  r12, r10, PPC44x_PTE_ADD_SHIFT, PPC44x_PTE_ADD_MASK_BIT, 28
        lwz     r11, 0(r12)             /* Get high word of pte entry */
        lwz     r12, 4(r12)             /* Get low word of pte entry */

        lis     r10,tlb_44x_index@ha

        andc.   r13,r13,r12             /* Check permission */

        /* Load the next available TLB index */
        lwz     r13,tlb_44x_index@l(r10)

        bne     2f                      /* Bail if permission mismach */

        /* Increment, rollover, and store TLB index */
        addi    r13,r13,1

        patch_site 0f, patch__tlb_44x_hwater_D
        /* Compare with watermark (instruction gets patched) */
0:      cmpwi   0,r13,1                 /* reserve entries */
        ble     5f
        li      r13,0
5:
        /* Store the next available TLB index */
        stw     r13,tlb_44x_index@l(r10)

        /* Re-load the faulting address */
        mfspr   r10,SPRN_DEAR

         /* Jump to common tlb load */
        b       finish_tlb_load_44x

2:
        /* The bailout.  Restore registers to pre-exception conditions
         * and call the heavyweights to help us out.
         */
        mfspr   r11, SPRN_SPRG_RSCRATCH4
        mtcr    r11
        mfspr   r13, SPRN_SPRG_RSCRATCH3
        mfspr   r12, SPRN_SPRG_RSCRATCH2
        mfspr   r11, SPRN_SPRG_RSCRATCH1
        mfspr   r10, SPRN_SPRG_RSCRATCH0
        b       DataStorage

        /* Instruction TLB Error Interrupt */
        /*
         * Nearly the same as above, except we get our
         * information from different registers and bailout
         * to a different point.
         */
        START_EXCEPTION(InstructionTLBError44x)
        mtspr   SPRN_SPRG_WSCRATCH0, r10 /* Save some working registers */
        mtspr   SPRN_SPRG_WSCRATCH1, r11
        mtspr   SPRN_SPRG_WSCRATCH2, r12
        mtspr   SPRN_SPRG_WSCRATCH3, r13
        mfcr    r11
        mtspr   SPRN_SPRG_WSCRATCH4, r11
        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

        mfspr   r12,SPRN_MMUCR
        rlwinm  r12,r12,0,0,23          /* Clear TID */

        b       4f

        /* Get the PGD for the current thread */
3:
        mfspr   r11,SPRN_SPRG_THREAD
        lwz     r11,PGDIR(r11)

        /* Load PID into MMUCR TID */
        mfspr   r12,SPRN_MMUCR
        mfspr   r13,SPRN_PID            /* Get PID */
        rlwimi  r12,r13,0,24,31         /* Set TID */

4:
        mtspr   SPRN_MMUCR,r12

        /* Make up the required permissions */
        li      r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC

        /* Compute pgdir/pmd offset */
        rlwinm  r12, r10, PPC44x_PGD_OFF_SHIFT, PPC44x_PGD_OFF_MASK_BIT, 29
        lwzx    r11, r12, r11           /* Get pgd/pmd entry */
        rlwinm. r12, r11, 0, 0, 20      /* Extract pt base address */
        beq     2f                      /* Bail if no table */

        /* Compute pte address */
        rlwimi  r12, r10, PPC44x_PTE_ADD_SHIFT, PPC44x_PTE_ADD_MASK_BIT, 28
        lwz     r11, 0(r12)             /* Get high word of pte entry */
        lwz     r12, 4(r12)             /* Get low word of pte entry */

        lis     r10,tlb_44x_index@ha

        andc.   r13,r13,r12             /* Check permission */

        /* Load the next available TLB index */
        lwz     r13,tlb_44x_index@l(r10)

        bne     2f                      /* Bail if permission mismach */

        /* Increment, rollover, and store TLB index */
        addi    r13,r13,1

        patch_site 0f, patch__tlb_44x_hwater_I
        /* Compare with watermark (instruction gets patched) */
0:      cmpwi   0,r13,1                 /* reserve entries */
        ble     5f
        li      r13,0
5:
        /* Store the next available TLB index */
        stw     r13,tlb_44x_index@l(r10)

        /* Re-load the faulting address */
        mfspr   r10,SPRN_SRR0

        /* Jump to common TLB load point */
        b       finish_tlb_load_44x

2:
        /* The bailout.  Restore registers to pre-exception conditions
         * and call the heavyweights to help us out.
         */
        mfspr   r11, SPRN_SPRG_RSCRATCH4
        mtcr    r11
        mfspr   r13, SPRN_SPRG_RSCRATCH3
        mfspr   r12, SPRN_SPRG_RSCRATCH2
        mfspr   r11, SPRN_SPRG_RSCRATCH1
        mfspr   r10, SPRN_SPRG_RSCRATCH0
        b       InstructionStorage

/*
 * Both the instruction and data TLB miss get to this
 * point to load the TLB.
 *      r10 - EA of fault
 *      r11 - PTE high word value
 *      r12 - PTE low word value
 *      r13 - TLB index
 *      MMUCR - loaded with proper value when we get here
 *      Upon exit, we reload everything and RFI.
 */
finish_tlb_load_44x:
        /* Combine RPN & ERPN an write WS 0 */
        rlwimi  r11,r12,0,0,31-PAGE_SHIFT
        tlbwe   r11,r13,PPC44x_TLB_XLAT

        /*
         * Create WS1. This is the faulting address (EPN),
         * page size, and valid flag.
         */
        li      r11,PPC44x_TLB_VALID | PPC44x_TLBE_SIZE
        /* Insert valid and page size */
        rlwimi  r10,r11,0,PPC44x_PTE_ADD_MASK_BIT,31
        tlbwe   r10,r13,PPC44x_TLB_PAGEID       /* Write PAGEID */

        /* And WS 2 */
        li      r10,0xf85                       /* Mask to apply from PTE */
        rlwimi  r10,r12,29,30,30                /* DIRTY -> SW position */
        and     r11,r12,r10                     /* Mask PTE bits to keep */
        andi.   r10,r12,_PAGE_USER              /* User page ? */
        beq     1f                              /* nope, leave U bits empty */
        rlwimi  r11,r11,3,26,28                 /* yes, copy S bits to U */
1:      tlbwe   r11,r13,PPC44x_TLB_ATTRIB       /* Write ATTRIB */

        /* Done...restore registers and get out of here.
        */
        mfspr   r11, SPRN_SPRG_RSCRATCH4
        mtcr    r11
        mfspr   r13, SPRN_SPRG_RSCRATCH3
        mfspr   r12, SPRN_SPRG_RSCRATCH2
        mfspr   r11, SPRN_SPRG_RSCRATCH1
        mfspr   r10, SPRN_SPRG_RSCRATCH0
        rfi                                     /* Force context change */

/* TLB error interrupts for 476
 */
#ifdef CONFIG_PPC_47x
        START_EXCEPTION(DataTLBError47x)
        mtspr   SPRN_SPRG_WSCRATCH0,r10 /* Save some working registers */
        mtspr   SPRN_SPRG_WSCRATCH1,r11
        mtspr   SPRN_SPRG_WSCRATCH2,r12
        mtspr   SPRN_SPRG_WSCRATCH3,r13
        mfcr    r11
        mtspr   SPRN_SPRG_WSCRATCH4,r11
        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   cr0,r10,r11
        blt+    3f
        lis     r11,swapper_pg_dir@h
        ori     r11,r11, swapper_pg_dir@l
        li      r12,0                   /* MMUCR = 0 */
        b       4f

        /* Get the PGD for the current thread and setup MMUCR */
3:      mfspr   r11,SPRN_SPRG3
        lwz     r11,PGDIR(r11)
        mfspr   r12,SPRN_PID            /* Get PID */
4:      mtspr   SPRN_MMUCR,r12          /* Set MMUCR */

        /* Mask of required permission bits. Note that while we
         * do copy ESR:ST to _PAGE_RW position as trying to write
         * to an RO page is pretty common, we don't do it with
         * _PAGE_DIRTY. We could do it, but it's a fairly rare
         * event so I'd rather take the overhead when it happens
         * rather than adding an instruction here. We should measure
         * whether the whole thing is worth it in the first place
         * as we could avoid loading SPRN_ESR completely in the first
         * place...
         *
         * TODO: Is it worth doing that mfspr & rlwimi in the first
         *       place or can we save a couple of instructions here ?
         */
        mfspr   r12,SPRN_ESR
        li      r13,_PAGE_PRESENT|_PAGE_ACCESSED
        rlwimi  r13,r12,10,30,30

        /* Load the PTE */
        /* Compute pgdir/pmd offset */
        rlwinm  r12,r10,PPC44x_PGD_OFF_SHIFT,PPC44x_PGD_OFF_MASK_BIT,29
        lwzx    r11,r12,r11             /* Get pgd/pmd entry */

        /* Word 0 is EPN,V,TS,DSIZ */
        li      r12,PPC47x_TLB0_VALID | PPC47x_TLBE_SIZE
        rlwimi  r10,r12,0,32-PAGE_SHIFT,31      /* Insert valid and page size*/
        li      r12,0
        tlbwe   r10,r12,0

        /* XXX can we do better ? Need to make sure tlbwe has established
         * latch V bit in MMUCR0 before the PTE is loaded further down */
#ifdef CONFIG_SMP
        isync
#endif

        rlwinm. r12,r11,0,0,20          /* Extract pt base address */
        /* Compute pte address */
        rlwimi  r12,r10,PPC44x_PTE_ADD_SHIFT,PPC44x_PTE_ADD_MASK_BIT,28
        beq     2f                      /* Bail if no table */
        lwz     r11,0(r12)              /* Get high word of pte entry */

        /* XXX can we do better ? maybe insert a known 0 bit from r11 into the
         * bottom of r12 to create a data dependency... We can also use r10
         * as destination nowadays
         */
#ifdef CONFIG_SMP
        lwsync
#endif
        lwz     r12,4(r12)              /* Get low word of pte entry */

        andc.   r13,r13,r12             /* Check permission */

         /* Jump to common tlb load */
        beq     finish_tlb_load_47x

2:      /* The bailout.  Restore registers to pre-exception conditions
         * and call the heavyweights to help us out.
         */
        mfspr   r11,SPRN_SPRG_RSCRATCH4
        mtcr    r11
        mfspr   r13,SPRN_SPRG_RSCRATCH3
        mfspr   r12,SPRN_SPRG_RSCRATCH2
        mfspr   r11,SPRN_SPRG_RSCRATCH1
        mfspr   r10,SPRN_SPRG_RSCRATCH0
        b       DataStorage

        /* Instruction TLB Error Interrupt */
        /*
         * Nearly the same as above, except we get our
         * information from different registers and bailout
         * to a different point.
         */
        START_EXCEPTION(InstructionTLBError47x)
        mtspr   SPRN_SPRG_WSCRATCH0,r10 /* Save some working registers */
        mtspr   SPRN_SPRG_WSCRATCH1,r11
        mtspr   SPRN_SPRG_WSCRATCH2,r12
        mtspr   SPRN_SPRG_WSCRATCH3,r13
        mfcr    r11
        mtspr   SPRN_SPRG_WSCRATCH4,r11
        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   cr0,r10,r11
        blt+    3f
        lis     r11,swapper_pg_dir@h
        ori     r11,r11, swapper_pg_dir@l
        li      r12,0                   /* MMUCR = 0 */
        b       4f

        /* Get the PGD for the current thread and setup MMUCR */
3:      mfspr   r11,SPRN_SPRG_THREAD
        lwz     r11,PGDIR(r11)
        mfspr   r12,SPRN_PID            /* Get PID */
4:      mtspr   SPRN_MMUCR,r12          /* Set MMUCR */

        /* Make up the required permissions */
        li      r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC

        /* Load PTE */
        /* Compute pgdir/pmd offset */
        rlwinm  r12,r10,PPC44x_PGD_OFF_SHIFT,PPC44x_PGD_OFF_MASK_BIT,29
        lwzx    r11,r12,r11             /* Get pgd/pmd entry */

        /* Word 0 is EPN,V,TS,DSIZ */
        li      r12,PPC47x_TLB0_VALID | PPC47x_TLBE_SIZE
        rlwimi  r10,r12,0,32-PAGE_SHIFT,31      /* Insert valid and page size*/
        li      r12,0
        tlbwe   r10,r12,0

        /* XXX can we do better ? Need to make sure tlbwe has established
         * latch V bit in MMUCR0 before the PTE is loaded further down */
#ifdef CONFIG_SMP
        isync
#endif

        rlwinm. r12,r11,0,0,20          /* Extract pt base address */
        /* Compute pte address */
        rlwimi  r12,r10,PPC44x_PTE_ADD_SHIFT,PPC44x_PTE_ADD_MASK_BIT,28
        beq     2f                      /* Bail if no table */

        lwz     r11,0(r12)              /* Get high word of pte entry */
        /* XXX can we do better ? maybe insert a known 0 bit from r11 into the
         * bottom of r12 to create a data dependency... We can also use r10
         * as destination nowadays
         */
#ifdef CONFIG_SMP
        lwsync
#endif
        lwz     r12,4(r12)              /* Get low word of pte entry */

        andc.   r13,r13,r12             /* Check permission */

        /* Jump to common TLB load point */
        beq     finish_tlb_load_47x

2:      /* The bailout.  Restore registers to pre-exception conditions
         * and call the heavyweights to help us out.
         */
        mfspr   r11, SPRN_SPRG_RSCRATCH4
        mtcr    r11
        mfspr   r13, SPRN_SPRG_RSCRATCH3
        mfspr   r12, SPRN_SPRG_RSCRATCH2
        mfspr   r11, SPRN_SPRG_RSCRATCH1
        mfspr   r10, SPRN_SPRG_RSCRATCH0
        b       InstructionStorage

/*
 * Both the instruction and data TLB miss get to this
 * point to load the TLB.
 *      r10 - free to use
 *      r11 - PTE high word value
 *      r12 - PTE low word value
 *      r13 - free to use
 *      MMUCR - loaded with proper value when we get here
 *      Upon exit, we reload everything and RFI.
 */
finish_tlb_load_47x:
        /* Combine RPN & ERPN an write WS 1 */
        rlwimi  r11,r12,0,0,31-PAGE_SHIFT
        tlbwe   r11,r13,1

        /* And make up word 2 */
        li      r10,0xf85                       /* Mask to apply from PTE */
        rlwimi  r10,r12,29,30,30                /* DIRTY -> SW position */
        and     r11,r12,r10                     /* Mask PTE bits to keep */
        andi.   r10,r12,_PAGE_USER              /* User page ? */
        beq     1f                              /* nope, leave U bits empty */
        rlwimi  r11,r11,3,26,28                 /* yes, copy S bits to U */
1:      tlbwe   r11,r13,2

        /* Done...restore registers and get out of here.
        */
        mfspr   r11, SPRN_SPRG_RSCRATCH4
        mtcr    r11
        mfspr   r13, SPRN_SPRG_RSCRATCH3
        mfspr   r12, SPRN_SPRG_RSCRATCH2
        mfspr   r11, SPRN_SPRG_RSCRATCH1
        mfspr   r10, SPRN_SPRG_RSCRATCH0
        rfi

#endif /* CONFIG_PPC_47x */

        /* Debug Interrupt */
        /*
         * This statement needs to exist at the end of the IVPR
         * definition just in case you end up taking a debug
         * exception within another exception.
         */
        DEBUG_CRIT_EXCEPTION

interrupt_end:

/*
 * Global functions
 */

/*
 * Adjust the machine check IVOR on 440A cores
 */
_GLOBAL(__fixup_440A_mcheck)
        li      r3,MachineCheckA@l
        mtspr   SPRN_IVOR1,r3
        sync
        blr

_GLOBAL(set_context)

#ifdef CONFIG_BDI_SWITCH
        /* Context switch the PTE pointer for the Abatron BDI2000.
         * The PGDIR is the second parameter.
         */
        lis     r5, abatron_pteptrs@h
        ori     r5, r5, abatron_pteptrs@l
        stw     r4, 0x4(r5)
#endif
        mtspr   SPRN_PID,r3
        isync                   /* Force context change */
        blr

/*
 * Init CPU state. This is called at boot time or for secondary CPUs
 * to setup initial TLB entries, setup IVORs, etc...
 *
 */
_GLOBAL(init_cpu_state)
        mflr    r22
#ifdef CONFIG_PPC_47x
        /* We use the PVR to differentiate 44x cores from 476 */
        mfspr   r3,SPRN_PVR
        srwi    r3,r3,16
        cmplwi  cr0,r3,PVR_476FPE@h
        beq     head_start_47x
        cmplwi  cr0,r3,PVR_476@h
        beq     head_start_47x
        cmplwi  cr0,r3,PVR_476_ISS@h
        beq     head_start_47x
#endif /* CONFIG_PPC_47x */

/*
 * In case the firmware didn't do it, we apply some workarounds
 * that are good for all 440 core variants here
 */
        mfspr   r3,SPRN_CCR0
        rlwinm  r3,r3,0,0,27    /* disable icache prefetch */
        isync
        mtspr   SPRN_CCR0,r3
        isync
        sync

/*
 * Set up the initial MMU state for 44x
 *
 * We are still executing code at the virtual address
 * mappings set by the firmware for the base of RAM.
 *
 * We first invalidate all TLB entries but the one
 * we are running from.  We then load the KERNELBASE
 * mappings so we can begin to use kernel addresses
 * natively and so the interrupt vector locations are
 * permanently pinned (necessary since Book E
 * implementations always have translation enabled).
 *
 * TODO: Use the known TLB entry we are running from to
 *       determine which physical region we are located
 *       in.  This can be used to determine where in RAM
 *       (on a shared CPU system) or PCI memory space
 *       (on a DRAMless system) we are located.
 *       For now, we assume a perfect world which means
 *       we are located at the base of DRAM (physical 0).
 */

/*
 * Search TLB for entry that we are currently using.
 * Invalidate all entries but the one we are using.
 */
        /* Load our current PID->MMUCR TID and MSR IS->MMUCR STS */
        mfspr   r3,SPRN_PID                     /* Get PID */
        mfmsr   r4                              /* Get MSR */
        andi.   r4,r4,MSR_IS@l                  /* TS=1? */
        beq     wmmucr                          /* If not, leave STS=0 */
        oris    r3,r3,PPC44x_MMUCR_STS@h        /* Set STS=1 */
wmmucr: mtspr   SPRN_MMUCR,r3                   /* Put MMUCR */
        sync

        bl      invstr                          /* Find our address */
invstr: mflr    r5                              /* Make it accessible */
        tlbsx   r23,0,r5                        /* Find entry we are in */
        li      r4,0                            /* Start at TLB entry 0 */
        li      r3,0                            /* Set PAGEID inval value */
1:      cmpw    r23,r4                          /* Is this our entry? */
        beq     skpinv                          /* If so, skip the inval */
        tlbwe   r3,r4,PPC44x_TLB_PAGEID         /* If not, inval the entry */
skpinv: addi    r4,r4,1                         /* Increment */
        cmpwi   r4,64                           /* Are we done? */
        bne     1b                              /* If not, repeat */
        isync                                   /* If so, context change */

/*
 * Configure and load pinned entry into TLB slot 63.
 */
#ifdef CONFIG_NONSTATIC_KERNEL
        /*
         * In case of a NONSTATIC_KERNEL we reuse the TLB XLAT
         * entries of the initial mapping set by the boot loader.
         * The XLAT entry is stored in r25
         */

        /* Read the XLAT entry for our current mapping */
        tlbre   r25,r23,PPC44x_TLB_XLAT

        lis     r3,KERNELBASE@h
        ori     r3,r3,KERNELBASE@l

        /* Use our current RPN entry */
        mr      r4,r25
#else

        lis     r3,PAGE_OFFSET@h
        ori     r3,r3,PAGE_OFFSET@l

        /* Kernel is at the base of RAM */
        li r4, 0                        /* Load the kernel physical address */
#endif

        /* Load the kernel PID = 0 */
        li      r0,0
        mtspr   SPRN_PID,r0
        sync

        /* Initialize MMUCR */
        li      r5,0
        mtspr   SPRN_MMUCR,r5
        sync

        /* pageid fields */
        clrrwi  r3,r3,10                /* Mask off the effective page number */
        ori     r3,r3,PPC44x_TLB_VALID | PPC44x_TLB_256M

        /* xlat fields */
        clrrwi  r4,r4,10                /* Mask off the real page number */
                                        /* ERPN is 0 for first 4GB page */

        /* attrib fields */
        /* Added guarded bit to protect against speculative loads/stores */
        li      r5,0
        ori     r5,r5,(PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G)

        li      r0,63                    /* TLB slot 63 */

        tlbwe   r3,r0,PPC44x_TLB_PAGEID /* Load the pageid fields */
        tlbwe   r4,r0,PPC44x_TLB_XLAT   /* Load the translation fields */
        tlbwe   r5,r0,PPC44x_TLB_ATTRIB /* Load the attrib/access fields */

        /* Force context change */
        mfmsr   r0
        mtspr   SPRN_SRR1, r0
        lis     r0,3f@h
        ori     r0,r0,3f@l
        mtspr   SPRN_SRR0,r0
        sync
        rfi

        /* If necessary, invalidate original entry we used */
3:      cmpwi   r23,63
        beq     4f
        li      r6,0
        tlbwe   r6,r23,PPC44x_TLB_PAGEID
        isync

4:
#ifdef CONFIG_PPC_EARLY_DEBUG_44x
        /* Add UART mapping for early debug. */

        /* pageid fields */
        lis     r3,PPC44x_EARLY_DEBUG_VIRTADDR@h
        ori     r3,r3,PPC44x_TLB_VALID|PPC44x_TLB_TS|PPC44x_TLB_64K

        /* xlat fields */
        lis     r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW@h
        ori     r4,r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSHIGH

        /* attrib fields */
        li      r5,(PPC44x_TLB_SW|PPC44x_TLB_SR|PPC44x_TLB_I|PPC44x_TLB_G)
        li      r0,62                    /* TLB slot 0 */

        tlbwe   r3,r0,PPC44x_TLB_PAGEID
        tlbwe   r4,r0,PPC44x_TLB_XLAT
        tlbwe   r5,r0,PPC44x_TLB_ATTRIB

        /* Force context change */
        isync
#endif /* CONFIG_PPC_EARLY_DEBUG_44x */

        /* Establish the interrupt vector offsets */
        SET_IVOR(0,  CriticalInput);
        SET_IVOR(1,  MachineCheck);
        SET_IVOR(2,  DataStorage);
        SET_IVOR(3,  InstructionStorage);
        SET_IVOR(4,  ExternalInput);
        SET_IVOR(5,  Alignment);
        SET_IVOR(6,  Program);
        SET_IVOR(7,  FloatingPointUnavailable);
        SET_IVOR(8,  SystemCall);
        SET_IVOR(9,  AuxillaryProcessorUnavailable);
        SET_IVOR(10, Decrementer);
        SET_IVOR(11, FixedIntervalTimer);
        SET_IVOR(12, WatchdogTimer);
        SET_IVOR(13, DataTLBError44x);
        SET_IVOR(14, InstructionTLBError44x);
        SET_IVOR(15, DebugCrit);

        b       head_start_common


#ifdef CONFIG_PPC_47x

#ifdef CONFIG_SMP

/* Entry point for secondary 47x processors */
_GLOBAL(start_secondary_47x)
        mr      r24,r3          /* CPU number */

        bl      init_cpu_state

        /* Now we need to bolt the rest of kernel memory which
         * is done in C code. We must be careful because our task
         * struct or our stack can (and will probably) be out
         * of reach of the initial 256M TLB entry, so we use a
         * small temporary stack in .bss for that. This works
         * because only one CPU at a time can be in this code
         */
        lis     r1,temp_boot_stack@h
        ori     r1,r1,temp_boot_stack@l
        addi    r1,r1,1024-STACK_FRAME_OVERHEAD
        li      r0,0
        stw     r0,0(r1)
        bl      mmu_init_secondary

        /* Now we can get our task struct and real stack pointer */

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

        /* Current stack pointer */
        addi    r1,r1,THREAD_SIZE-STACK_FRAME_OVERHEAD
        li      r0,0
        stw     r0,0(r1)

        /* Kernel stack for exception entry in SPRG3 */
        addi    r4,r2,THREAD    /* init task's THREAD */
        mtspr   SPRN_SPRG3,r4

        b       start_secondary

#endif /* CONFIG_SMP */

/*
 * Set up the initial MMU state for 44x
 *
 * We are still executing code at the virtual address
 * mappings set by the firmware for the base of RAM.
 */

head_start_47x:
        /* Load our current PID->MMUCR TID and MSR IS->MMUCR STS */
        mfspr   r3,SPRN_PID                     /* Get PID */
        mfmsr   r4                              /* Get MSR */
        andi.   r4,r4,MSR_IS@l                  /* TS=1? */
        beq     1f                              /* If not, leave STS=0 */
        oris    r3,r3,PPC47x_MMUCR_STS@h        /* Set STS=1 */
1:      mtspr   SPRN_MMUCR,r3                   /* Put MMUCR */
        sync

        /* Find the entry we are running from */
        bl      1f
1:      mflr    r23
        tlbsx   r23,0,r23
        tlbre   r24,r23,0
        tlbre   r25,r23,1
        tlbre   r26,r23,2

/*
 * Cleanup time
 */

        /* Initialize MMUCR */
        li      r5,0
        mtspr   SPRN_MMUCR,r5
        sync

clear_all_utlb_entries:

        #; Set initial values.

        addis           r3,0,0x8000
        addi            r4,0,0
        addi            r5,0,0
        b               clear_utlb_entry

        #; Align the loop to speed things up.

        .align          6

clear_utlb_entry:

        tlbwe           r4,r3,0
        tlbwe           r5,r3,1
        tlbwe           r5,r3,2
        addis           r3,r3,0x2000
        cmpwi           r3,0
        bne             clear_utlb_entry
        addis           r3,0,0x8000
        addis           r4,r4,0x100
        cmpwi           r4,0
        bne             clear_utlb_entry

        #; Restore original entry.

        oris    r23,r23,0x8000  /* specify the way */
        tlbwe           r24,r23,0
        tlbwe           r25,r23,1
        tlbwe           r26,r23,2

/*
 * Configure and load pinned entry into TLB for the kernel core
 */

        lis     r3,PAGE_OFFSET@h
        ori     r3,r3,PAGE_OFFSET@l

        /* Load the kernel PID = 0 */
        li      r0,0
        mtspr   SPRN_PID,r0
        sync

        /* Word 0 */
        clrrwi  r3,r3,12                /* Mask off the effective page number */
        ori     r3,r3,PPC47x_TLB0_VALID | PPC47x_TLB0_256M

        /* Word 1 - use r25.  RPN is the same as the original entry */

        /* Word 2 */
        li      r5,0
        ori     r5,r5,PPC47x_TLB2_S_RWX
#ifdef CONFIG_SMP
        ori     r5,r5,PPC47x_TLB2_M
#endif

        /* We write to way 0 and bolted 0 */
        lis     r0,0x8800
        tlbwe   r3,r0,0
        tlbwe   r25,r0,1
        tlbwe   r5,r0,2

/*
 * Configure SSPCR, ISPCR and USPCR for now to search everything, we can fix
 * them up later
 */
        LOAD_REG_IMMEDIATE(r3, 0x9abcdef0)
        mtspr   SPRN_SSPCR,r3
        mtspr   SPRN_USPCR,r3
        LOAD_REG_IMMEDIATE(r3, 0x12345670)
        mtspr   SPRN_ISPCR,r3

        /* Force context change */
        mfmsr   r0
        mtspr   SPRN_SRR1, r0
        lis     r0,3f@h
        ori     r0,r0,3f@l
        mtspr   SPRN_SRR0,r0
        sync
        rfi

        /* Invalidate original entry we used */
3:
        rlwinm  r24,r24,0,21,19 /* clear the "valid" bit */
        tlbwe   r24,r23,0
        addi    r24,0,0
        tlbwe   r24,r23,1
        tlbwe   r24,r23,2
        isync                   /* Clear out the shadow TLB entries */

#ifdef CONFIG_PPC_EARLY_DEBUG_44x
        /* Add UART mapping for early debug. */

        /* Word 0 */
        lis     r3,PPC44x_EARLY_DEBUG_VIRTADDR@h
        ori     r3,r3,PPC47x_TLB0_VALID | PPC47x_TLB0_TS | PPC47x_TLB0_1M

        /* Word 1 */
        lis     r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSLOW@h
        ori     r4,r4,CONFIG_PPC_EARLY_DEBUG_44x_PHYSHIGH

        /* Word 2 */
        li      r5,(PPC47x_TLB2_S_RW | PPC47x_TLB2_IMG)

        /* Bolted in way 0, bolt slot 5, we -hope- we don't hit the same
         * congruence class as the kernel, we need to make sure of it at
         * some point
         */
        lis     r0,0x8d00
        tlbwe   r3,r0,0
        tlbwe   r4,r0,1
        tlbwe   r5,r0,2

        /* Force context change */
        isync
#endif /* CONFIG_PPC_EARLY_DEBUG_44x */

        /* Establish the interrupt vector offsets */
        SET_IVOR(0,  CriticalInput);
        SET_IVOR(1,  MachineCheckA);
        SET_IVOR(2,  DataStorage);
        SET_IVOR(3,  InstructionStorage);
        SET_IVOR(4,  ExternalInput);
        SET_IVOR(5,  Alignment);
        SET_IVOR(6,  Program);
        SET_IVOR(7,  FloatingPointUnavailable);
        SET_IVOR(8,  SystemCall);
        SET_IVOR(9,  AuxillaryProcessorUnavailable);
        SET_IVOR(10, Decrementer);
        SET_IVOR(11, FixedIntervalTimer);
        SET_IVOR(12, WatchdogTimer);
        SET_IVOR(13, DataTLBError47x);
        SET_IVOR(14, InstructionTLBError47x);
        SET_IVOR(15, DebugCrit);

        /* We configure icbi to invalidate 128 bytes at a time since the
         * current 32-bit kernel code isn't too happy with icache != dcache
         * block size. We also disable the BTAC as this can cause errors
         * in some circumstances (see IBM Erratum 47).
         */
        mfspr   r3,SPRN_CCR0
        oris    r3,r3,0x0020
        ori     r3,r3,0x0040
        mtspr   SPRN_CCR0,r3
        isync

#endif /* CONFIG_PPC_47x */

/*
 * Here we are back to code that is common between 44x and 47x
 *
 * We proceed to further kernel initialization and return to the
 * main kernel entry
 */
head_start_common:
        /* Establish the interrupt vector base */
        lis     r4,interrupt_base@h     /* IVPR only uses the high 16-bits */
        mtspr   SPRN_IVPR,r4

        /*
         * If the kernel was loaded at a non-zero 256 MB page, we need to
         * mask off the most significant 4 bits to get the relative address
         * from the start of physical memory
         */
        rlwinm  r22,r22,0,4,31
        addis   r22,r22,PAGE_OFFSET@h
        mtlr    r22
        isync
        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  PAGE_SHIFT
        .globl  sdata
sdata:
        .globl  empty_zero_page
empty_zero_page:
        .space  PAGE_SIZE
EXPORT_SYMBOL(empty_zero_page)

/*
 * To support >32-bit physical addresses, we use an 8KB pgdir.
 */
        .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

#ifdef CONFIG_SMP
        .align  12
temp_boot_stack:
        .space  1024
#endif /* CONFIG_SMP */