/* * BK Id: %F% %I% %G% %U% %#% */ /* * arch/ppc/kernel/except_8xx.S * * 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 * Low-level exception handlers and MMU support * rewritten by Paul Mackerras. * Copyright (C) 1996 Paul Mackerras. * MPC8xx modifications by Dan Malek * Copyright (C) 1997 Dan Malek (dmalek@jlc.net). * * This file contains low-level support and setup for PowerPC 8xx * embedded processors, including trap and interrupt dispatch. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. * */ #include #include #include #include #include #include #include #include #include "ppc_defs.h" .text .globl _stext _stext: /* * _start is defined this way because the XCOFF loader in the OpenFirmware * on the powermac expects the entry point to be a procedure descriptor. */ .text .globl _start _start: /* MPC8xx * This port was done on an MBX board with an 860. Right now I only * support an ELF compressed (zImage) boot from EPPC-Bug because the * code there loads up some registers before calling us: * r3: ptr to board info 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 * * I decided to use conditional compilation instead of checking PVR and * adding more processor specific branches around code I don't need. * Since this is an embedded processor, I also appreciate any memory * savings I can get. * * The MPC8xx does not have any BATs, but it supports large page sizes. * We first initialize the MMU to support 8M byte pages, then load one * entry into each of the instruction and data TLBs to map the first * 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to * the "internal" processor registers before MMU_init is called. * * The TLB code currently contains a major hack. Since I use the condition * code register, I have to save and restore it. I am out of registers, so * I just store it in memory location 0 (the TLB handlers are not reentrant). * To avoid making any decisions, I need to use the "segment" valid bit * in the first level table, but that would require many changes to the * Linux page directory/table functions that I don't want to do right now. * * I used to use SPRG2 for a temporary register in the TLB handler, but it * has since been put to other uses. I now use a hack to save a register * and the CCR at memory location 0.....Someday I'll fix this..... * -- Dan */ .globl __start __start: mr r31,r3 /* save parameters */ mr r30,r4 mr r29,r5 mr r28,r6 mr r27,r7 li r24,0 /* cpu # */ /* We have to turn on the MMU right away so we get cache modes * set correctly. */ bl initial_mmu /* We now have the lower 8 Meg mapped into TLB entries, and the caches * ready to work. */ turn_on_mmu: mfmsr r0 ori r0,r0,MSR_DR|MSR_IR mtspr SRR1,r0 lis r0,start_here@h ori r0,r0,start_here@l mtspr SRR0,r0 SYNC rfi /* enables MMU */ /* * Exception entry code. This code runs with address translation * turned off, i.e. using physical addresses. * We assume sprg3 has the physical address of the current * task's thread_struct. */ #define EXCEPTION_PROLOG \ mtspr SPRG0,r20; \ mtspr SPRG1,r21; \ mfcr r20; \ mfspr r21,SPRG2; /* exception stack to use from */ \ cmpwi 0,r21,0; /* user mode or RTAS */ \ bne 1f; \ tophys(r21,r1); /* use tophys(kernel sp) otherwise */ \ subi r21,r21,INT_FRAME_SIZE; /* alloc exc. frame */\ 1: stw r20,_CCR(r21); /* save registers */ \ stw r22,GPR22(r21); \ stw r23,GPR23(r21); \ mfspr r20,SPRG0; \ stw r20,GPR20(r21); \ mfspr r22,SPRG1; \ stw r22,GPR21(r21); \ mflr r20; \ stw r20,_LINK(r21); \ mfctr r22; \ stw r22,_CTR(r21); \ mfspr r20,XER; \ stw r20,_XER(r21); \ mfspr r22,SRR0; \ mfspr r23,SRR1; \ stw r0,GPR0(r21); \ stw r1,GPR1(r21); \ stw r2,GPR2(r21); \ stw r1,0(r21); \ tovirt(r1,r21); /* set new kernel sp */ \ SAVE_4GPRS(3, r21); \ SAVE_GPR(7, r21); /* * Note: code which follows this uses cr0.eq (set if from kernel), * r21, r22 (SRR0), and r23 (SRR1). */ /* * Exception vectors. */ #define FINISH_EXCEPTION(func) \ bl transfer_to_handler; \ .long func; \ .long ret_from_except #define STD_EXCEPTION(n, label, hdlr) \ . = n; \ label: \ EXCEPTION_PROLOG; \ addi r3,r1,STACK_FRAME_OVERHEAD; \ li r20,MSR_KERNEL; \ FINISH_EXCEPTION(hdlr) /* System reset */ STD_EXCEPTION(0x100, Reset, UnknownException) /* Machine check */ STD_EXCEPTION(0x200, MachineCheck, MachineCheckException) /* Data access exception. * This is "never generated" by the MPC8xx. We jump to it for other * translation errors. */ . = 0x300 DataAccess: EXCEPTION_PROLOG mfspr r20,DSISR stw r20,_DSISR(r21) mr r5,r20 mfspr r4,DAR stw r4,_DAR(r21) addi r3,r1,STACK_FRAME_OVERHEAD li r20,MSR_KERNEL rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ FINISH_EXCEPTION(do_page_fault) /* Instruction access exception. * This is "never generated" by the MPC8xx. We jump to it for other * translation errors. */ . = 0x400 InstructionAccess: EXCEPTION_PROLOG addi r3,r1,STACK_FRAME_OVERHEAD mr r4,r22 mr r5,r23 li r20,MSR_KERNEL rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ FINISH_EXCEPTION(do_page_fault) /* External interrupt */ . = 0x500; HardwareInterrupt: EXCEPTION_PROLOG; addi r3,r1,STACK_FRAME_OVERHEAD li r20,MSR_KERNEL li r4,0 bl transfer_to_handler .globl do_IRQ_intercept do_IRQ_intercept: .long do_IRQ; .long ret_from_intercept /* Alignment exception */ . = 0x600 Alignment: EXCEPTION_PROLOG mfspr r4,DAR stw r4,_DAR(r21) mfspr r5,DSISR stw r5,_DSISR(r21) addi r3,r1,STACK_FRAME_OVERHEAD li r20,MSR_KERNEL rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ FINISH_EXCEPTION(AlignmentException) /* Program check exception */ . = 0x700 ProgramCheck: EXCEPTION_PROLOG addi r3,r1,STACK_FRAME_OVERHEAD li r20,MSR_KERNEL rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ FINISH_EXCEPTION(ProgramCheckException) /* No FPU on MPC8xx. This exception is not supposed to happen. */ STD_EXCEPTION(0x800, FPUnavailable, UnknownException) . = 0x900 Decrementer: EXCEPTION_PROLOG addi r3,r1,STACK_FRAME_OVERHEAD li r20,MSR_KERNEL bl transfer_to_handler .globl timer_interrupt_intercept timer_interrupt_intercept: .long timer_interrupt .long ret_from_intercept STD_EXCEPTION(0xa00, Trap_0a, UnknownException) STD_EXCEPTION(0xb00, Trap_0b, UnknownException) /* System call */ . = 0xc00 SystemCall: EXCEPTION_PROLOG stw r3,ORIG_GPR3(r21) li r20,MSR_KERNEL rlwimi r20,r23,0,16,16 /* copy EE bit from saved MSR */ FINISH_EXCEPTION(DoSyscall) /* Single step - not used on 601 */ STD_EXCEPTION(0xd00, SingleStep, SingleStepException) STD_EXCEPTION(0xe00, Trap_0e, UnknownException) STD_EXCEPTION(0xf00, Trap_0f, UnknownException) /* On the MPC8xx, this is a software emulation interrupt. It occurs * for all unimplemented and illegal instructions. */ STD_EXCEPTION(0x1000, SoftEmu, SoftwareEmulation) . = 0x1100 /* * For the MPC8xx, this is a software tablewalk to load the instruction * TLB. It is modelled after the example in the Motorola manual. The task * switch loads the M_TWB register with the pointer to the first level table. * If we discover there is no second level table (the value is zero), the * plan was to load that into the TLB, which causes another fault into the * TLB Error interrupt where we can handle such problems. However, that did * not work, so if we discover there is no second level table, we restore * registers and branch to the error exception. We have to use the MD_xxx * registers for the tablewalk because the equivalent MI_xxx registers * only perform the attribute functions. */ InstructionTLBMiss: #ifdef CONFIG_8xx_CPU6 stw r3, 8(r0) li r3, 0x3f80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr M_TW, r20 /* Save a couple of working registers */ mfcr r20 stw r20, 0(r0) stw r21, 4(r0) mfspr r20, SRR0 /* Get effective address of fault */ #ifdef CONFIG_8xx_CPU6 li r3, 0x3780 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_EPN, r20 /* Have to use MD_EPN for walk, MI_EPN can't */ mfspr r20, M_TWB /* Get level 1 table entry address */ /* If we are faulting a kernel address, we have to use the * kernel page tables. */ andi. r21, r20, 0x0800 /* Address >= 0x80000000 */ beq 3f lis r21, swapper_pg_dir@h ori r21, r21, swapper_pg_dir@l rlwimi r20, r21, 0, 2, 19 3: lwz r21, 0(r20) /* Get the level 1 entry */ rlwinm. r20, r21,0,0,19 /* Extract page descriptor page address */ beq 2f /* If zero, don't try to find a pte */ /* We have a pte table, so load the MI_TWC with the attributes * for this page, which has only bit 31 set. */ tophys(r21,r21) ori r21,r21,1 /* Set valid bit */ #ifdef CONFIG_8xx_CPU6 li r3, 0x2b80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MI_TWC, r21 /* Set page attributes */ #ifdef CONFIG_8xx_CPU6 li r3, 0x3b80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_TWC, r21 /* Load pte table base address */ mfspr r21, MD_TWC /* ....and get the pte address */ lwz r20, 0(r21) /* Get the pte */ ori r20, r20, _PAGE_ACCESSED stw r20, 0(r21) /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 21, 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ li r21, 0x0600 andc r20, r20, r21 /* Clear 21, 22 */ li r21, 0x00f0 rlwimi r20, r21, 0, 24, 28 /* Set 24-27, clear 28 */ #ifdef CONFIG_8xx_CPU6 li r3, 0x2d80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MI_RPN, r20 /* Update TLB entry */ mfspr r20, M_TW /* Restore registers */ lwz r21, 0(r0) mtcr r21 lwz r21, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif rfi 2: mfspr r20, M_TW /* Restore registers */ lwz r21, 0(r0) mtcr r21 lwz r21, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif b InstructionAccess . = 0x1200 DataStoreTLBMiss: #ifdef CONFIG_8xx_CPU6 stw r3, 8(r0) li r3, 0x3f80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr M_TW, r20 /* Save a couple of working registers */ mfcr r20 stw r20, 0(r0) stw r21, 4(r0) mfspr r20, M_TWB /* Get level 1 table entry address */ /* If we are faulting a kernel address, we have to use the * kernel page tables. */ andi. r21, r20, 0x0800 beq 3f lis r21, swapper_pg_dir@h ori r21, r21, swapper_pg_dir@l rlwimi r20, r21, 0, 2, 19 3: lwz r21, 0(r20) /* Get the level 1 entry */ rlwinm. r20, r21,0,0,19 /* Extract page descriptor page address */ beq 2f /* If zero, don't try to find a pte */ /* We have a pte table, so load fetch the pte from the table. */ tophys(r21, r21) ori r21, r21, 1 /* Set valid bit in physical L2 page */ #ifdef CONFIG_8xx_CPU6 li r3, 0x3b80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_TWC, r21 /* Load pte table base address */ mfspr r20, MD_TWC /* ....and get the pte address */ lwz r20, 0(r20) /* Get the pte */ /* Insert the Guarded flag into the TWC from the Linux PTE. * It is bit 27 of both the Linux PTE and the TWC (at least * I got that right :-). It will be better when we can put * this into the Linux pgd/pmd and load it in the operation * above. */ rlwimi r21, r20, 0, 27, 27 #ifdef CONFIG_8xx_CPU6 li r3, 0x3b80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_TWC, r21 mfspr r21, MD_TWC /* get the pte address again */ ori r20, r20, _PAGE_ACCESSED stw r20, 0(r21) /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 21, 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ li r21, 0x0600 andc r20, r20, r21 /* Clear 21, 22 */ li r21, 0x00f0 rlwimi r20, r21, 0, 24, 28 /* Set 24-27, clear 28 */ #ifdef CONFIG_8xx_CPU6 li r3, 0x3d80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_RPN, r20 /* Update TLB entry */ mfspr r20, M_TW /* Restore registers */ lwz r21, 0(r0) mtcr r21 lwz r21, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif rfi 2: mfspr r20, M_TW /* Restore registers */ lwz r21, 0(r0) mtcr r21 lwz r21, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif b DataAccess /* This is an instruction TLB error on the MPC8xx. This could be due * to many reasons, such as executing guarded memory or illegal instruction * addresses. There is nothing to do but handle a big time error fault. */ . = 0x1300 InstructionTLBError: b InstructionAccess /* This is the data TLB error on the MPC8xx. This could be due to * many reasons, including a dirty update to a pte. We can catch that * one here, but anything else is an error. First, we track down the * Linux pte. If it is valid, write access is allowed, but the * page dirty bit is not set, we will set it and reload the TLB. For * any other case, we bail out to a higher level function that can * handle it. */ . = 0x1400 DataTLBError: #ifdef CONFIG_8xx_CPU6 stw r3, 8(r0) li r3, 0x3f80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr M_TW, r20 /* Save a couple of working registers */ mfcr r20 stw r20, 0(r0) stw r21, 4(r0) /* First, make sure this was a store operation. */ mfspr r20, DSISR andis. r21, r20, 0x0200 /* If set, indicates store op */ beq 2f /* The EA of a data TLB miss is automatically stored in the MD_EPN * register. The EA of a data TLB error is automatically stored in * the DAR, but not the MD_EPN register. We must copy the 20 most * significant bits of the EA from the DAR to MD_EPN before we * start walking the page tables. We also need to copy the CASID * value from the M_CASID register. * Addendum: The EA of a data TLB error is _supposed_ to be stored * in DAR, but it seems that this doesn't happen in some cases, such * as when the error is due to a dcbi instruction to a page with a * TLB that doesn't have the changed bit set. In such cases, there * does not appear to be any way to recover the EA of the error * since it is neither in DAR nor MD_EPN. As a workaround, the * _PAGE_HWWRITE bit is set for all kernel data pages when the PTEs * are initialized in mapin_ram(). This will avoid the problem, * assuming we only use the dcbi instruction on kernel addresses. */ mfspr r20, DAR rlwinm r21, r20, 0, 0, 19 ori r21, r21, MD_EVALID mfspr r20, M_CASID rlwimi r21, r20, 0, 28, 31 #ifdef CONFIG_8xx_CPU6 li r3, 0x3780 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_EPN, r21 mfspr r20, M_TWB /* Get level 1 table entry address */ /* If we are faulting a kernel address, we have to use the * kernel page tables. */ andi. r21, r20, 0x0800 beq 3f lis r21, swapper_pg_dir@h ori r21, r21, swapper_pg_dir@l rlwimi r20, r21, 0, 2, 19 3: lwz r21, 0(r20) /* Get the level 1 entry */ rlwinm. r20, r21,0,0,19 /* Extract page descriptor page address */ beq 2f /* If zero, bail */ /* We have a pte table, so fetch the pte from the table. */ tophys(r21, r21) ori r21, r21, 1 /* Set valid bit in physical L2 page */ #ifdef CONFIG_8xx_CPU6 li r3, 0x3b80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_TWC, r21 /* Load pte table base address */ mfspr r21, MD_TWC /* ....and get the pte address */ lwz r20, 0(r21) /* Get the pte */ andi. r21, r20, _PAGE_RW /* Is it writeable? */ beq 2f /* Bail out if not */ /* Update 'changed', among others. */ ori r20, r20, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE mfspr r21, MD_TWC /* Get pte address again */ stw r20, 0(r21) /* and update pte in table */ /* The Linux PTE won't go exactly into the MMU TLB. * Software indicator bits 21, 22 and 28 must be clear. * Software indicator bits 24, 25, 26, and 27 must be * set. All other Linux PTE bits control the behavior * of the MMU. */ li r21, 0x0600 andc r20, r20, r21 /* Clear 21, 22 */ li r21, 0x00f0 rlwimi r20, r21, 0, 24, 28 /* Set 24-27, clear 28 */ #ifdef CONFIG_8xx_CPU6 li r3, 0x3d80 stw r3, 12(r0) lwz r3, 12(r0) #endif mtspr MD_RPN, r20 /* Update TLB entry */ mfspr r20, M_TW /* Restore registers */ lwz r21, 0(r0) mtcr r21 lwz r21, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif rfi 2: mfspr r20, M_TW /* Restore registers */ lwz r21, 0(r0) mtcr r21 lwz r21, 4(r0) #ifdef CONFIG_8xx_CPU6 lwz r3, 8(r0) #endif b DataAccess STD_EXCEPTION(0x1500, Trap_15, UnknownException) STD_EXCEPTION(0x1600, Trap_16, UnknownException) STD_EXCEPTION(0x1700, Trap_17, TAUException) STD_EXCEPTION(0x1800, Trap_18, UnknownException) STD_EXCEPTION(0x1900, Trap_19, UnknownException) STD_EXCEPTION(0x1a00, Trap_1a, UnknownException) STD_EXCEPTION(0x1b00, Trap_1b, UnknownException) /* On the MPC8xx, these next four traps are used for development * support of breakpoints and such. Someday I will get around to * using them. */ STD_EXCEPTION(0x1c00, Trap_1c, UnknownException) STD_EXCEPTION(0x1d00, Trap_1d, UnknownException) STD_EXCEPTION(0x1e00, Trap_1e, UnknownException) STD_EXCEPTION(0x1f00, Trap_1f, UnknownException) . = 0x2000 /* * This code finishes saving the registers to the exception frame * and jumps to the appropriate handler for the exception, turning * on address translation. */ .globl transfer_to_handler transfer_to_handler: stw r22,_NIP(r21) lis r22,MSR_POW@h andc r23,r23,r22 stw r23,_MSR(r21) SAVE_4GPRS(8, r21) SAVE_8GPRS(12, r21) SAVE_8GPRS(24, r21) andi. r23,r23,MSR_PR mfspr r23,SPRG3 /* if from user, fix up THREAD.regs */ beq 2f addi r24,r1,STACK_FRAME_OVERHEAD stw r24,PT_REGS(r23) 2: addi r2,r23,-THREAD /* set r2 to current */ tovirt(r2,r2) mflr r23 andi. r24,r23,0x3f00 /* get vector offset */ stw r24,TRAP(r21) li r22,0 stw r22,RESULT(r21) mtspr SPRG2,r22 /* r1 is now kernel sp */ addi r24,r2,TASK_STRUCT_SIZE /* check for kernel stack overflow */ cmplw 0,r1,r2 cmplw 1,r1,r24 crand 1,1,4 bgt- stack_ovf /* if r2 < r1 < r2+TASK_STRUCT_SIZE */ lwz r24,0(r23) /* virtual address of handler */ lwz r23,4(r23) /* where to go when done */ mtspr SRR0,r24 mtspr SRR1,r20 mtlr r23 SYNC rfi /* jump to handler, enable MMU */ /* * On kernel stack overflow, load up an initial stack pointer * and call StackOverflow(regs), which should not return. */ stack_ovf: addi r3,r1,STACK_FRAME_OVERHEAD lis r1,init_task_union@ha addi r1,r1,init_task_union@l addi r1,r1,TASK_UNION_SIZE-STACK_FRAME_OVERHEAD lis r24,StackOverflow@ha addi r24,r24,StackOverflow@l li r20,MSR_KERNEL mtspr SRR0,r24 mtspr SRR1,r20 SYNC rfi .globl giveup_fpu giveup_fpu: blr /* Maybe someday....... */ _GLOBAL(__setup_cpu_8xx) blr /* * This is where the main kernel code starts. */ start_here: /* ptr to current */ lis r2,init_task_union@h ori r2,r2,init_task_union@l /* ptr to phys current thread */ tophys(r4,r2) addi r4,r4,THREAD /* init task's THREAD */ mtspr SPRG3,r4 li r3,0 mtspr SPRG2,r3 /* 0 => r1 has kernel sp */ /* stack */ addi r1,r2,TASK_UNION_SIZE li r0,0 stwu r0,-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. */ mr r3,r31 mr r4,r30 mr r5,r29 mr r6,r28 mr r7,r27 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 8xx, all we have to do is invalidate the TLB to clear * the old 8M byte TLB mappings and load the page table base register. */ /* The right way to do this would be to track it down through * init's THREAD like the context switch code does, but this is * easier......until someone changes init's static structures. */ lis r6, swapper_pg_dir@h ori r6, r6, swapper_pg_dir@l tophys(r6,r6) #ifdef CONFIG_8xx_CPU6 lis r4, cpu6_errata_word@h ori r4, r4, cpu6_errata_word@l li r3, 0x3980 stw r3, 12(r4) lwz r3, 12(r4) #endif mtspr M_TWB, r6 lis r4,2f@h ori r4,r4,2f@l tophys(r4,r4) li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR) mtspr SRR0,r4 mtspr SRR1,r3 rfi /* Load up the kernel context */ 2: SYNC /* Force all PTE updates to finish */ tlbia /* Clear all TLB entries */ sync /* wait for tlbia/tlbie to finish */ TLBSYNC /* ... on all CPUs */ #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. */ tovirt(r6,r6) lis r5, abatron_pteptrs@h ori r5, r5, abatron_pteptrs@l stw r5, 0xf0(r0) /* Must match your Abatron config file */ tophys(r5,r5) stw r6, 0(r5) #endif /* Now turn on the MMU for real! */ li r4,MSR_KERNEL lis r3,start_kernel@h ori r3,r3,start_kernel@l mtspr SRR0,r3 mtspr SRR1,r4 rfi /* enable MMU and jump to start_kernel */ /* Set up the initial MMU state so we can do the first level of * kernel initialization. This maps the first 8 MBytes of memory 1:1 * virtual to physical. Also, set the cache mode since that is defined * by TLB entries and perform any additional mapping (like of the IMMR). */ initial_mmu: tlbia /* Invalidate all TLB entries */ li r8, 0 mtspr MI_CTR, r8 /* Set instruction control to zero */ lis r8, MD_RESETVAL@h #ifndef CONFIG_8xx_COPYBACK oris r8, r8, MD_WTDEF@h #endif mtspr MD_CTR, r8 /* Set data TLB control */ /* Now map the lower 8 Meg into the TLBs. For this quick hack, * we can load the instruction and data TLB registers with the * same values. */ lis r8, KERNELBASE@h /* Create vaddr for TLB */ ori r8, r8, MI_EVALID /* Mark it valid */ mtspr MI_EPN, r8 mtspr MD_EPN, r8 li r8, MI_PS8MEG /* Set 8M byte page */ ori r8, r8, MI_SVALID /* Make it valid */ mtspr MI_TWC, r8 mtspr MD_TWC, r8 li r8, MI_BOOTINIT /* Create RPN for address 0 */ mtspr MI_RPN, r8 /* Store TLB entry */ mtspr MD_RPN, r8 lis r8, MI_Kp@h /* Set the protection mode */ mtspr MI_AP, r8 mtspr MD_AP, r8 /* Map another 8 MByte at the IMMR to get the processor * internal registers (among other things). */ mfspr r9, 638 /* Get current IMMR */ andis. r9, r9, 0xff80 /* Get 8Mbyte boundary */ mr r8, r9 /* Create vaddr for TLB */ ori r8, r8, MD_EVALID /* Mark it valid */ mtspr MD_EPN, r8 li r8, MD_PS8MEG /* Set 8M byte page */ ori r8, r8, MD_SVALID /* Make it valid */ mtspr MD_TWC, r8 mr r8, r9 /* Create paddr for TLB */ ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */ mtspr MD_RPN, r8 /* Since the cache is enabled according to the information we * just loaded into the TLB, invalidate and enable the caches here. * We should probably check/set other modes....later. */ lis r8, IDC_INVALL@h mtspr IC_CST, r8 mtspr DC_CST, r8 lis r8, IDC_ENABLE@h mtspr IC_CST, r8 #ifdef CONFIG_8xx_COPYBACK mtspr DC_CST, r8 #else /* For a debug option, I left this here to easily enable * the write through cache mode */ lis r8, DC_SFWT@h mtspr DC_CST, r8 lis r8, IDC_ENABLE@h mtspr DC_CST, r8 #endif blr /* * Set up to use a given MMU context. * r3 is context number, r4 is PGD pointer. * * We place the physical address of the new task page directory loaded * into the MMU base register, and set the ASID compare register with * the new "context." */ _GLOBAL(set_context) #ifdef CONFIG_BDI_SWITCH /* Context switch the PTE pointer for the Abatron BDI2000. * The PGDIR is passed as second argument. */ lis r5, KERNELBASE@h lwz r5, 0xf0(r5) stw r4, 0x4(r5) #endif #ifdef CONFIG_8xx_CPU6 lis r6, cpu6_errata_word@h ori r6, r6, cpu6_errata_word@l tophys (r4, r4) li r7, 0x3980 stw r7, 12(r6) lwz r7, 12(r6) mtspr M_TWB, r4 /* Update MMU base address */ li r7, 0x3380 stw r7, 12(r6) lwz r7, 12(r6) mtspr M_CASID, r3 /* Update context */ #else mtspr M_CASID,r3 /* Update context */ tophys (r4, r4) mtspr M_TWB, r4 /* and pgd */ #endif SYNC blr #ifdef CONFIG_8xx_CPU6 /* It's here because it is unique to the 8xx. * It is important we get called with interrupts disabled. I used to * do that, but it appears that all code that calls this already had * interrupt disabled. */ .globl set_dec_cpu6 set_dec_cpu6: lis r7, cpu6_errata_word@h ori r7, r7, cpu6_errata_word@l li r4, 0x2c00 stw r4, 8(r7) lwz r4, 8(r7) mtspr 22, r3 /* Update Decrementer */ SYNC 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 .globl swapper_pg_dir swapper_pg_dir: .space 4096 /* * This space gets a copy of optional info passed to us by the bootstrap * Used to pass parameters into the kernel like root=/dev/sda1, etc. */ .globl cmd_line cmd_line: .space 512 #ifdef CONFIG_BDI_SWITCH /* Room for two PTE table poiners, usually the kernel and current user * pointer to their respective root page table (pgdir). */ abatron_pteptrs: .space 8 #endif #ifdef CONFIG_8xx_CPU6 .globl cpu6_errata_word cpu6_errata_word: .space 16 #endif