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Diffstat (limited to 'arch/powerpc/kernel/head_40x.S')
| -rw-r--r-- | arch/powerpc/kernel/head_40x.S | 718 |
1 files changed, 718 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S new file mode 100644 index 000000000..088f50089 --- /dev/null +++ b/arch/powerpc/kernel/head_40x.S @@ -0,0 +1,718 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright (c) 1995-1996 Gary Thomas <gdt@linuxppc.org> + * Initial PowerPC version. + * Copyright (c) 1996 Cort Dougan <cort@cs.nmt.edu> + * Rewritten for PReP + * Copyright (c) 1996 Paul Mackerras <paulus@cs.anu.edu.au> + * Low-level exception handers, MMU support, and rewrite. + * Copyright (c) 1997 Dan Malek <dmalek@jlc.net> + * PowerPC 8xx modifications. + * Copyright (c) 1998-1999 TiVo, Inc. + * PowerPC 403GCX modifications. + * Copyright (c) 1999 Grant Erickson <grant@lcse.umn.edu> + * PowerPC 403GCX/405GP modifications. + * Copyright 2000 MontaVista Software Inc. + * PPC405 modifications + * PowerPC 403GCX/405GP modifications. + * Author: MontaVista Software, Inc. + * frank_rowand@mvista.com or source@mvista.com + * debbie_chu@mvista.com + * + * Module name: head_4xx.S + * + * Description: + * Kernel execution entry point code. + */ + +#include <linux/init.h> +#include <linux/pgtable.h> +#include <linux/sizes.h> +#include <asm/processor.h> +#include <asm/page.h> +#include <asm/mmu.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/export.h> + +#include "head_32.h" + +/* As with the other PowerPC ports, it is expected that when code + * execution begins here, the following registers contain valid, yet + * optional, information: + * + * r3 - Board info structure pointer (DRAM, frequency, MAC address, etc.) + * r4 - Starting address of the init RAM disk + * r5 - Ending address of the init RAM disk + * r6 - Start of kernel command line string (e.g. "mem=96m") + * r7 - End of kernel command line string + * + * This is all going to change RSN when we add bi_recs....... -- Dan + */ + __HEAD +_GLOBAL(_stext); +_GLOBAL(_start); + + mr r31,r3 /* save device tree ptr */ + + /* We have to turn on the MMU right away so we get cache modes + * set correctly. + */ + bl initial_mmu + +/* We now have the lower 16 Meg mapped into TLB entries, and the caches + * ready to work. + */ +turn_on_mmu: + lis r0,MSR_KERNEL@h + ori r0,r0,MSR_KERNEL@l + mtspr SPRN_SRR1,r0 + lis r0,start_here@h + ori r0,r0,start_here@l + mtspr SPRN_SRR0,r0 + rfi /* enables MMU */ + b . /* prevent prefetch past rfi */ + +/* + * This area is used for temporarily saving registers during the + * critical exception prolog. + */ + . = 0xc0 +crit_save: +_GLOBAL(crit_r10) + .space 4 +_GLOBAL(crit_r11) + .space 4 +_GLOBAL(crit_srr0) + .space 4 +_GLOBAL(crit_srr1) + .space 4 +_GLOBAL(crit_r1) + .space 4 +_GLOBAL(crit_dear) + .space 4 +_GLOBAL(crit_esr) + .space 4 + +/* + * Exception prolog for critical exceptions. This is a little different + * from the normal exception prolog above since a critical exception + * can potentially occur at any point during normal exception processing. + * Thus we cannot use the same SPRG registers as the normal prolog above. + * Instead we use a couple of words of memory at low physical addresses. + * This is OK since we don't support SMP on these processors. + */ +.macro CRITICAL_EXCEPTION_PROLOG trapno name + stw r10,crit_r10@l(0) /* save two registers to work with */ + stw r11,crit_r11@l(0) + mfspr r10,SPRN_SRR0 + mfspr r11,SPRN_SRR1 + stw r10,crit_srr0@l(0) + stw r11,crit_srr1@l(0) + mfspr r10,SPRN_DEAR + mfspr r11,SPRN_ESR + stw r10,crit_dear@l(0) + stw r11,crit_esr@l(0) + mfcr r10 /* save CR in r10 for now */ + mfspr r11,SPRN_SRR3 /* check whether user or kernel */ + andi. r11,r11,MSR_PR + lis r11,(critirq_ctx-PAGE_OFFSET)@ha + lwz r11,(critirq_ctx-PAGE_OFFSET)@l(r11) + beq 1f + /* COMING FROM USER MODE */ + mfspr r11,SPRN_SPRG_THREAD /* if from user, start at top of */ + lwz r11,TASK_STACK-THREAD(r11) /* this thread's kernel stack */ +1: stw r1,crit_r1@l(0) + addi r1,r11,THREAD_SIZE-INT_FRAME_SIZE /* Alloc an excpt frm */ + LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)) /* re-enable MMU */ + mtspr SPRN_SRR1, r11 + lis r11, 1f@h + ori r11, r11, 1f@l + mtspr SPRN_SRR0, r11 + rfi + + .text +1: +\name\()_virt: + lwz r11,crit_r1@l(0) + stw r11,GPR1(r1) + stw r11,0(r1) + mr r11,r1 + stw r10,_CCR(r11) /* save various registers */ + stw r12,GPR12(r11) + stw r9,GPR9(r11) + mflr r10 + stw r10,_LINK(r11) + lis r9,PAGE_OFFSET@ha + lwz r10,crit_r10@l(r9) + lwz r12,crit_r11@l(r9) + stw r10,GPR10(r11) + stw r12,GPR11(r11) + lwz r12,crit_dear@l(r9) + lwz r9,crit_esr@l(r9) + stw r12,_DEAR(r11) /* since they may have had stuff */ + stw r9,_ESR(r11) /* exception was taken */ + mfspr r12,SPRN_SRR2 + mfspr r9,SPRN_SRR3 + rlwinm r9,r9,0,14,12 /* clear MSR_WE (necessary?) */ + COMMON_EXCEPTION_PROLOG_END \trapno + 2 +_ASM_NOKPROBE_SYMBOL(\name\()_virt) +.endm + + /* + * State at this point: + * r9 saved in stack frame, now saved SRR3 & ~MSR_WE + * r10 saved in crit_r10 and in stack frame, trashed + * r11 saved in crit_r11 and in stack frame, + * now phys stack/exception frame pointer + * r12 saved in stack frame, now saved SRR2 + * CR saved in stack frame, CR0.EQ = !SRR3.PR + * LR, DEAR, ESR in stack frame + * r1 saved in stack frame, now virt stack/excframe pointer + * r0, r3-r8 saved in stack frame + */ + +/* + * Exception vectors. + */ +#define CRITICAL_EXCEPTION(n, label, hdlr) \ + START_EXCEPTION(n, label); \ + CRITICAL_EXCEPTION_PROLOG n label; \ + prepare_transfer_to_handler; \ + bl hdlr; \ + b ret_from_crit_exc + +/* + * 0x0100 - Critical Interrupt Exception + */ + CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, unknown_exception) + +/* + * 0x0200 - Machine Check Exception + */ + CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception) + +/* + * 0x0300 - Data Storage Exception + * This happens for just a few reasons. U0 set (but we don't do that), + * or zone protection fault (user violation, write to protected page). + * The other Data TLB exceptions bail out to this point + * if they can't resolve the lightweight TLB fault. + */ + START_EXCEPTION(0x0300, DataStorage) + EXCEPTION_PROLOG 0x300 DataStorage handle_dar_dsisr=1 + prepare_transfer_to_handler + bl do_page_fault + b interrupt_return + +/* + * 0x0400 - Instruction Storage Exception + * This is caused by a fetch from non-execute or guarded pages. + */ + START_EXCEPTION(0x0400, InstructionAccess) + EXCEPTION_PROLOG 0x400 InstructionAccess + li r5,0 + stw r5, _ESR(r11) /* Zero ESR */ + stw r12, _DEAR(r11) /* SRR0 as DEAR */ + prepare_transfer_to_handler + bl do_page_fault + b interrupt_return + +/* 0x0500 - External Interrupt Exception */ + EXCEPTION(0x0500, HardwareInterrupt, do_IRQ) + +/* 0x0600 - Alignment Exception */ + START_EXCEPTION(0x0600, Alignment) + EXCEPTION_PROLOG 0x600 Alignment handle_dar_dsisr=1 + prepare_transfer_to_handler + bl alignment_exception + REST_NVGPRS(r1) + b interrupt_return + +/* 0x0700 - Program Exception */ + START_EXCEPTION(0x0700, ProgramCheck) + EXCEPTION_PROLOG 0x700 ProgramCheck handle_dar_dsisr=1 + prepare_transfer_to_handler + bl program_check_exception + REST_NVGPRS(r1) + b interrupt_return + + EXCEPTION(0x0800, Trap_08, unknown_exception) + EXCEPTION(0x0900, Trap_09, unknown_exception) + EXCEPTION(0x0A00, Trap_0A, unknown_exception) + EXCEPTION(0x0B00, Trap_0B, unknown_exception) + +/* 0x0C00 - System Call Exception */ + START_EXCEPTION(0x0C00, SystemCall) + SYSCALL_ENTRY 0xc00 +/* Trap_0D is commented out to get more space for system call exception */ + +/* EXCEPTION(0x0D00, Trap_0D, unknown_exception) */ + EXCEPTION(0x0E00, Trap_0E, unknown_exception) + EXCEPTION(0x0F00, Trap_0F, unknown_exception) + +/* 0x1000 - Programmable Interval Timer (PIT) Exception */ + START_EXCEPTION(0x1000, DecrementerTrap) + b Decrementer + +/* 0x1010 - Fixed Interval Timer (FIT) Exception */ + START_EXCEPTION(0x1010, FITExceptionTrap) + b FITException + +/* 0x1020 - Watchdog Timer (WDT) Exception */ + START_EXCEPTION(0x1020, WDTExceptionTrap) + b WDTException + +/* 0x1100 - Data TLB Miss Exception + * As the name implies, translation is not in the MMU, so search the + * page tables and fix it. The only purpose of this function is to + * load TLB entries from the page table if they exist. + */ + START_EXCEPTION(0x1100, DTLBMiss) + mtspr SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */ + mtspr SPRN_SPRG_SCRATCH6, r11 + mtspr SPRN_SPRG_SCRATCH3, r12 + mtspr SPRN_SPRG_SCRATCH4, r9 + mfcr r12 + mfspr r9, SPRN_PID + rlwimi r12, r9, 0, 0xff + mfspr r10, SPRN_DEAR /* Get faulting address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + lis r11, PAGE_OFFSET@h + cmplw r10, r11 + blt+ 3f + lis r11, swapper_pg_dir@h + ori r11, r11, swapper_pg_dir@l + li r9, 0 + mtspr SPRN_PID, r9 /* TLB will have 0 TID */ + b 4f + + /* Get the PGD for the current thread. + */ +3: + mfspr r11,SPRN_SPRG_THREAD + lwz r11,PGDIR(r11) +#ifdef CONFIG_PPC_KUAP + rlwinm. r9, r9, 0, 0xff + beq 5f /* Kuap fault */ +#endif +4: + tophys(r11, r11) + rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ + lwz r11, 0(r11) /* Get L1 entry */ + andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ + beq 2f /* Bail if no table */ + + rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ + lwz r11, 0(r11) /* Get Linux PTE */ + li r9, _PAGE_PRESENT | _PAGE_ACCESSED + andc. r9, r9, r11 /* Check permission */ + bne 5f + + rlwinm r9, r11, 1, _PAGE_RW /* dirty => rw */ + and r9, r9, r11 /* hwwrite = dirty & rw */ + rlwimi r11, r9, 0, _PAGE_RW /* replace rw by hwwrite */ + + /* Create TLB tag. This is the faulting address plus a static + * set of bits. These are size, valid, E, U0. + */ + li r9, 0x00c0 + rlwimi r10, r9, 0, 20, 31 + + b finish_tlb_load + +2: /* Check for possible large-page pmd entry */ + rlwinm. r9, r11, 2, 22, 24 + beq 5f + + /* Create TLB tag. This is the faulting address, plus a static + * set of bits (valid, E, U0) plus the size from the PMD. + */ + ori r9, r9, 0x40 + rlwimi r10, r9, 0, 20, 31 + + b finish_tlb_load + +5: + /* The bailout. Restore registers to pre-exception conditions + * and call the heavyweights to help us out. + */ + mtspr SPRN_PID, r12 + mtcrf 0x80, r12 + mfspr r9, SPRN_SPRG_SCRATCH4 + mfspr r12, SPRN_SPRG_SCRATCH3 + mfspr r11, SPRN_SPRG_SCRATCH6 + mfspr r10, SPRN_SPRG_SCRATCH5 + b DataStorage + +/* 0x1200 - Instruction TLB Miss Exception + * Nearly the same as above, except we get our information from different + * registers and bailout to a different point. + */ + START_EXCEPTION(0x1200, ITLBMiss) + mtspr SPRN_SPRG_SCRATCH5, r10 /* Save some working registers */ + mtspr SPRN_SPRG_SCRATCH6, r11 + mtspr SPRN_SPRG_SCRATCH3, r12 + mtspr SPRN_SPRG_SCRATCH4, r9 + mfcr r12 + mfspr r9, SPRN_PID + rlwimi r12, r9, 0, 0xff + mfspr r10, SPRN_SRR0 /* Get faulting address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + lis r11, PAGE_OFFSET@h + cmplw r10, r11 + blt+ 3f + lis r11, swapper_pg_dir@h + ori r11, r11, swapper_pg_dir@l + li r9, 0 + mtspr SPRN_PID, r9 /* TLB will have 0 TID */ + b 4f + + /* Get the PGD for the current thread. + */ +3: + mfspr r11,SPRN_SPRG_THREAD + lwz r11,PGDIR(r11) +#ifdef CONFIG_PPC_KUAP + rlwinm. r9, r9, 0, 0xff + beq 5f /* Kuap fault */ +#endif +4: + tophys(r11, r11) + rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ + lwz r11, 0(r11) /* Get L1 entry */ + andi. r9, r11, _PMD_PRESENT /* Check if it points to a PTE page */ + beq 2f /* Bail if no table */ + + rlwimi r11, r10, 22, 20, 29 /* Compute PTE address */ + lwz r11, 0(r11) /* Get Linux PTE */ + li r9, _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC + andc. r9, r9, r11 /* Check permission */ + bne 5f + + rlwinm r9, r11, 1, _PAGE_RW /* dirty => rw */ + and r9, r9, r11 /* hwwrite = dirty & rw */ + rlwimi r11, r9, 0, _PAGE_RW /* replace rw by hwwrite */ + + /* Create TLB tag. This is the faulting address plus a static + * set of bits. These are size, valid, E, U0. + */ + li r9, 0x00c0 + rlwimi r10, r9, 0, 20, 31 + + b finish_tlb_load + +2: /* Check for possible large-page pmd entry */ + rlwinm. r9, r11, 2, 22, 24 + beq 5f + + /* Create TLB tag. This is the faulting address, plus a static + * set of bits (valid, E, U0) plus the size from the PMD. + */ + ori r9, r9, 0x40 + rlwimi r10, r9, 0, 20, 31 + + b finish_tlb_load + +5: + /* The bailout. Restore registers to pre-exception conditions + * and call the heavyweights to help us out. + */ + mtspr SPRN_PID, r12 + mtcrf 0x80, r12 + mfspr r9, SPRN_SPRG_SCRATCH4 + mfspr r12, SPRN_SPRG_SCRATCH3 + mfspr r11, SPRN_SPRG_SCRATCH6 + mfspr r10, SPRN_SPRG_SCRATCH5 + b InstructionAccess + + EXCEPTION(0x1300, Trap_13, unknown_exception) + EXCEPTION(0x1400, Trap_14, unknown_exception) + EXCEPTION(0x1500, Trap_15, unknown_exception) + EXCEPTION(0x1600, Trap_16, unknown_exception) + EXCEPTION(0x1700, Trap_17, unknown_exception) + EXCEPTION(0x1800, Trap_18, unknown_exception) + EXCEPTION(0x1900, Trap_19, unknown_exception) + EXCEPTION(0x1A00, Trap_1A, unknown_exception) + EXCEPTION(0x1B00, Trap_1B, unknown_exception) + EXCEPTION(0x1C00, Trap_1C, unknown_exception) + EXCEPTION(0x1D00, Trap_1D, unknown_exception) + EXCEPTION(0x1E00, Trap_1E, unknown_exception) + EXCEPTION(0x1F00, Trap_1F, unknown_exception) + +/* Check for a single step debug exception while in an exception + * handler before state has been saved. This is to catch the case + * where an instruction that we are trying to single step causes + * an exception (eg ITLB/DTLB miss) and thus the first instruction of + * the exception handler generates a single step debug exception. + * + * If we get a debug trap on the first instruction of an exception handler, + * we reset the MSR_DE in the _exception handler's_ MSR (the debug trap is + * a critical exception, so we are using SPRN_CSRR1 to manipulate the MSR). + * The exception handler was handling a non-critical interrupt, so it will + * save (and later restore) the MSR via SPRN_SRR1, which will still have + * the MSR_DE bit set. + */ + /* 0x2000 - Debug Exception */ + START_EXCEPTION(0x2000, DebugTrap) + CRITICAL_EXCEPTION_PROLOG 0x2000 DebugTrap + + /* + * If this is a single step or branch-taken exception in an + * exception entry sequence, it was probably meant to apply to + * the code where the exception occurred (since exception entry + * doesn't turn off DE automatically). We simulate the effect + * of turning off DE on entry to an exception handler by turning + * off DE in the SRR3 value and clearing the debug status. + */ + mfspr r10,SPRN_DBSR /* check single-step/branch taken */ + andis. r10,r10,DBSR_IC@h + beq+ 2f + + andi. r10,r9,MSR_IR|MSR_PR /* check supervisor + MMU off */ + beq 1f /* branch and fix it up */ + + mfspr r10,SPRN_SRR2 /* Faulting instruction address */ + cmplwi r10,0x2100 + bgt+ 2f /* address above exception vectors */ + + /* here it looks like we got an inappropriate debug exception. */ +1: rlwinm r9,r9,0,~MSR_DE /* clear DE in the SRR3 value */ + lis r10,DBSR_IC@h /* clear the IC event */ + mtspr SPRN_DBSR,r10 + /* restore state and get out */ + lwz r10,_CCR(r11) + lwz r0,GPR0(r11) + lwz r1,GPR1(r11) + mtcrf 0x80,r10 + mtspr SPRN_SRR2,r12 + mtspr SPRN_SRR3,r9 + lwz r9,GPR9(r11) + lwz r12,GPR12(r11) + lwz r10,crit_r10@l(0) + lwz r11,crit_r11@l(0) + rfci + b . + + /* continue normal handling for a critical exception... */ +2: mfspr r4,SPRN_DBSR + stw r4,_ESR(r11) /* DebugException takes DBSR in _ESR */ + prepare_transfer_to_handler + bl DebugException + b ret_from_crit_exc + + /* Programmable Interval Timer (PIT) Exception. (from 0x1000) */ + __HEAD +Decrementer: + EXCEPTION_PROLOG 0x1000 Decrementer + lis r0,TSR_PIS@h + mtspr SPRN_TSR,r0 /* Clear the PIT exception */ + prepare_transfer_to_handler + bl timer_interrupt + b interrupt_return + + /* Fixed Interval Timer (FIT) Exception. (from 0x1010) */ + __HEAD +FITException: + EXCEPTION_PROLOG 0x1010 FITException + prepare_transfer_to_handler + bl unknown_exception + b interrupt_return + + /* Watchdog Timer (WDT) Exception. (from 0x1020) */ + __HEAD +WDTException: + CRITICAL_EXCEPTION_PROLOG 0x1020 WDTException + prepare_transfer_to_handler + bl WatchdogException + b ret_from_crit_exc + +/* Other PowerPC processors, namely those derived from the 6xx-series + * have vectors from 0x2100 through 0x2F00 defined, but marked as reserved. + * However, for the 4xx-series processors these are neither defined nor + * reserved. + */ + + __HEAD + /* Damn, I came up one instruction too many to fit into the + * exception space :-). Both the instruction and data TLB + * miss get to this point to load the TLB. + * r10 - TLB_TAG value + * r11 - Linux PTE + * r9 - available to use + * PID - loaded with proper value when we get here + * Upon exit, we reload everything and RFI. + * Actually, it will fit now, but oh well.....a common place + * to load the TLB. + */ +tlb_4xx_index: + .long 0 +finish_tlb_load: + /* + * Clear out the software-only bits in the PTE to generate the + * TLB_DATA value. These are the bottom 2 bits of the RPM, the + * top 3 bits of the zone field, and M. + */ + li r9, 0x0ce2 + andc r11, r11, r9 + + /* load the next available TLB index. */ + lwz r9, tlb_4xx_index@l(0) + addi r9, r9, 1 + andi. r9, r9, PPC40X_TLB_SIZE - 1 + stw r9, tlb_4xx_index@l(0) + + tlbwe r11, r9, TLB_DATA /* Load TLB LO */ + tlbwe r10, r9, TLB_TAG /* Load TLB HI */ + + /* Done...restore registers and get out of here. + */ + mtspr SPRN_PID, r12 + mtcrf 0x80, r12 + mfspr r9, SPRN_SPRG_SCRATCH4 + mfspr r12, SPRN_SPRG_SCRATCH3 + mfspr r11, SPRN_SPRG_SCRATCH6 + mfspr r10, SPRN_SPRG_SCRATCH5 + rfi /* Should sync shadow TLBs */ + b . /* prevent prefetch past rfi */ + +/* This is where the main kernel code starts. + */ +start_here: + + /* ptr to current */ + lis r2,init_task@h + ori r2,r2,init_task@l + + /* ptr to phys current thread */ + tophys(r4,r2) + addi r4,r4,THREAD /* init task's THREAD */ + mtspr SPRN_SPRG_THREAD,r4 + + /* stack */ + lis r1,init_thread_union@ha + addi r1,r1,init_thread_union@l + li r0,0 + stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1) + + bl early_init /* We have to do this with MMU on */ + +/* + * Decide what sort of machine this is and initialize the MMU. + */ +#ifdef CONFIG_KASAN + bl kasan_early_init +#endif + li r3,0 + mr r4,r31 + bl machine_init + bl MMU_init + +/* Go back to running unmapped so we can load up new values + * and change to using our exception vectors. + * On the 4xx, all we have to do is invalidate the TLB to clear + * the old 16M byte TLB mappings. + */ + lis r4,2f@h + ori r4,r4,2f@l + tophys(r4,r4) + lis r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@h + ori r3,r3,(MSR_KERNEL & ~(MSR_IR|MSR_DR))@l + mtspr SPRN_SRR0,r4 + mtspr SPRN_SRR1,r3 + rfi + b . /* prevent prefetch past rfi */ + +/* Load up the kernel context */ +2: + sync /* Flush to memory before changing TLB */ + tlbia + isync /* Flush shadow TLBs */ + + /* set up the PTE pointers for the Abatron bdiGDB. + */ + lis r6, swapper_pg_dir@h + ori r6, r6, swapper_pg_dir@l + lis r5, abatron_pteptrs@h + ori r5, r5, abatron_pteptrs@l + stw r5, 0xf0(0) /* Must match your Abatron config file */ + tophys(r5,r5) + stw r6, 0(r5) + +/* Now turn on the MMU for real! */ + lis r4,MSR_KERNEL@h + ori r4,r4,MSR_KERNEL@l + lis r3,start_kernel@h + ori r3,r3,start_kernel@l + mtspr SPRN_SRR0,r3 + mtspr SPRN_SRR1,r4 + rfi /* enable MMU and jump to start_kernel */ + b . /* prevent prefetch past rfi */ + +/* Set up the initial MMU state so we can do the first level of + * kernel initialization. This maps the first 32 MBytes of memory 1:1 + * virtual to physical and more importantly sets the cache mode. + */ +initial_mmu: + tlbia /* Invalidate all TLB entries */ + isync + + /* We should still be executing code at physical address 0x0000xxxx + * at this point. However, start_here is at virtual address + * 0xC000xxxx. So, set up a TLB mapping to cover this once + * translation is enabled. + */ + + lis r3,KERNELBASE@h /* Load the kernel virtual address */ + ori r3,r3,KERNELBASE@l + tophys(r4,r3) /* Load the kernel physical address */ + + iccci r0,r3 /* Invalidate the i-cache before use */ + + /* Load the kernel PID. + */ + li r0,0 + mtspr SPRN_PID,r0 + sync + + /* Configure and load one entry into TLB slots 63 */ + clrrwi r4,r4,10 /* Mask off the real page number */ + ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */ + + clrrwi r3,r3,10 /* Mask off the effective page number */ + ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M)) + + li r0,63 /* TLB slot 63 */ + + tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */ + tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */ + + li r0,62 /* TLB slot 62 */ + addis r4,r4,SZ_16M@h + addis r3,r3,SZ_16M@h + tlbwe r4,r0,TLB_DATA /* Load the data portion of the entry */ + tlbwe r3,r0,TLB_TAG /* Load the tag portion of the entry */ + + isync + + /* Establish the exception vector base + */ + lis r4,KERNELBASE@h /* EVPR only uses the high 16-bits */ + tophys(r0,r4) /* Use the physical address */ + mtspr SPRN_EVPR,r0 + + blr + +_GLOBAL(abort) + mfspr r13,SPRN_DBCR0 + oris r13,r13,DBCR0_RST_SYSTEM@h + mtspr SPRN_DBCR0,r13 |