diff options
Diffstat (limited to 'arch/ppc/kernel/head_4xx.S')
| -rw-r--r-- | arch/ppc/kernel/head_4xx.S | 1010 |
1 files changed, 1010 insertions, 0 deletions
diff --git a/arch/ppc/kernel/head_4xx.S b/arch/ppc/kernel/head_4xx.S new file mode 100644 index 00000000000..6f5d380e234 --- /dev/null +++ b/arch/ppc/kernel/head_4xx.S @@ -0,0 +1,1010 @@ +/* + * 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. + * + * 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 <linux/config.h> +#include <asm/processor.h> +#include <asm/page.h> +#include <asm/mmu.h> +#include <asm/pgtable.h> +#include <asm/ibm4xx.h> +#include <asm/cputable.h> +#include <asm/thread_info.h> +#include <asm/ppc_asm.h> +#include <asm/offsets.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 + */ + .text +_GLOBAL(_stext) +_GLOBAL(_start) + + /* Save parameters we are passed. + */ + mr r31,r3 + mr r30,r4 + mr r29,r5 + mr r28,r6 + mr r27,r7 + + /* 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 + SYNC + 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 + +/* + * Exception vector 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 thread_struct. + * Note that we have to have decremented r1 before we write to any fields + * of the exception frame, since a critical interrupt could occur at any + * time, and it will write to the area immediately below the current r1. + */ +#define NORMAL_EXCEPTION_PROLOG \ + mtspr SPRN_SPRG0,r10; /* save two registers to work with */\ + mtspr SPRN_SPRG1,r11; \ + mtspr SPRN_SPRG2,r1; \ + mfcr r10; /* save CR in r10 for now */\ + mfspr r11,SPRN_SRR1; /* check whether user or kernel */\ + andi. r11,r11,MSR_PR; \ + beq 1f; \ + mfspr r1,SPRN_SPRG3; /* if from user, start at top of */\ + lwz r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack */\ + addi r1,r1,THREAD_SIZE; \ +1: subi r1,r1,INT_FRAME_SIZE; /* Allocate an exception frame */\ + tophys(r11,r1); \ + stw r10,_CCR(r11); /* save various registers */\ + stw r12,GPR12(r11); \ + stw r9,GPR9(r11); \ + mfspr r10,SPRN_SPRG0; \ + stw r10,GPR10(r11); \ + mfspr r12,SPRN_SPRG1; \ + stw r12,GPR11(r11); \ + mflr r10; \ + stw r10,_LINK(r11); \ + mfspr r10,SPRN_SPRG2; \ + mfspr r12,SPRN_SRR0; \ + stw r10,GPR1(r11); \ + mfspr r9,SPRN_SRR1; \ + stw r10,0(r11); \ + rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\ + stw r0,GPR0(r11); \ + SAVE_4GPRS(3, r11); \ + SAVE_2GPRS(7, r11) + +/* + * 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. + */ +#define CRITICAL_EXCEPTION_PROLOG \ + stw r10,crit_r10@l(0); /* save two registers to work with */\ + stw r11,crit_r11@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,critical_stack_top@h; \ + ori r11,r11,critical_stack_top@l; \ + beq 1f; \ + /* COMING FROM USER MODE */ \ + mfspr r11,SPRN_SPRG3; /* if from user, start at top of */\ + lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\ + addi r11,r11,THREAD_SIZE; \ +1: subi r11,r11,INT_FRAME_SIZE; /* Allocate an exception frame */\ + tophys(r11,r11); \ + stw r10,_CCR(r11); /* save various registers */\ + stw r12,GPR12(r11); \ + stw r9,GPR9(r11); \ + mflr r10; \ + stw r10,_LINK(r11); \ + mfspr r12,SPRN_DEAR; /* save DEAR and ESR in the frame */\ + stw r12,_DEAR(r11); /* since they may have had stuff */\ + mfspr r9,SPRN_ESR; /* in them at the point where the */\ + stw r9,_ESR(r11); /* exception was taken */\ + mfspr r12,SPRN_SRR2; \ + stw r1,GPR1(r11); \ + mfspr r9,SPRN_SRR3; \ + stw r1,0(r11); \ + tovirt(r1,r11); \ + rlwinm r9,r9,0,14,12; /* clear MSR_WE (necessary?) */\ + stw r0,GPR0(r11); \ + SAVE_4GPRS(3, r11); \ + SAVE_2GPRS(7, r11) + + /* + * 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 START_EXCEPTION(n, label) \ + . = n; \ +label: + +#define EXCEPTION(n, label, hdlr, xfer) \ + START_EXCEPTION(n, label); \ + NORMAL_EXCEPTION_PROLOG; \ + addi r3,r1,STACK_FRAME_OVERHEAD; \ + xfer(n, hdlr) + +#define CRITICAL_EXCEPTION(n, label, hdlr) \ + START_EXCEPTION(n, label); \ + CRITICAL_EXCEPTION_PROLOG; \ + addi r3,r1,STACK_FRAME_OVERHEAD; \ + EXC_XFER_TEMPLATE(hdlr, n+2, (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \ + NOCOPY, crit_transfer_to_handler, \ + ret_from_crit_exc) + +#define EXC_XFER_TEMPLATE(hdlr, trap, msr, copyee, tfer, ret) \ + li r10,trap; \ + stw r10,TRAP(r11); \ + lis r10,msr@h; \ + ori r10,r10,msr@l; \ + copyee(r10, r9); \ + bl tfer; \ + .long hdlr; \ + .long ret + +#define COPY_EE(d, s) rlwimi d,s,0,16,16 +#define NOCOPY(d, s) + +#define EXC_XFER_STD(n, hdlr) \ + EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, NOCOPY, transfer_to_handler_full, \ + ret_from_except_full) + +#define EXC_XFER_LITE(n, hdlr) \ + EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \ + ret_from_except) + +#define EXC_XFER_EE(n, hdlr) \ + EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \ + ret_from_except_full) + +#define EXC_XFER_EE_LITE(n, hdlr) \ + EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, COPY_EE, transfer_to_handler, \ + ret_from_except) + + +/* + * 0x0100 - Critical Interrupt Exception + */ + CRITICAL_EXCEPTION(0x0100, CriticalInterrupt, UnknownException) + +/* + * 0x0200 - Machine Check Exception + */ + CRITICAL_EXCEPTION(0x0200, MachineCheck, MachineCheckException) + +/* + * 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). + * If this is just an update of modified status, we do that quickly + * and exit. Otherwise, we call heavywight functions to do the work. + */ + START_EXCEPTION(0x0300, DataStorage) + mtspr SPRN_SPRG0, r10 /* Save some working registers */ + mtspr SPRN_SPRG1, r11 +#ifdef CONFIG_403GCX + stw r12, 0(r0) + stw r9, 4(r0) + mfcr r11 + mfspr r12, SPRN_PID + stw r11, 8(r0) + stw r12, 12(r0) +#else + mtspr SPRN_SPRG4, r12 + mtspr SPRN_SPRG5, r9 + mfcr r11 + mfspr r12, SPRN_PID + mtspr SPRN_SPRG7, r11 + mtspr SPRN_SPRG6, r12 +#endif + + /* First, check if it was a zone fault (which means a user + * tried to access a kernel or read-protected page - always + * a SEGV). All other faults here must be stores, so no + * need to check ESR_DST as well. */ + mfspr r10, SPRN_ESR + andis. r10, r10, ESR_DIZ@h + bne 2f + + mfspr r10, SPRN_DEAR /* Get faulting address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + andis. r11, r10, 0x8000 + beq 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_SPRG3 + lwz r11,PGDIR(r11) +4: + tophys(r11, r11) + rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ + lwz r11, 0(r11) /* Get L1 entry */ + rlwinm. r12, r11, 0, 0, 19 /* Extract L2 (pte) base address */ + beq 2f /* Bail if no table */ + + rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */ + lwz r11, 0(r12) /* Get Linux PTE */ + + andi. r9, r11, _PAGE_RW /* Is it writeable? */ + beq 2f /* Bail if not */ + + /* Update 'changed'. + */ + ori r11, r11, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE + stw r11, 0(r12) /* Update Linux page table */ + + /* Most of the Linux PTE is ready to load into the TLB LO. + * We set ZSEL, where only the LS-bit determines user access. + * We set execute, because we don't have the granularity to + * properly set this at the page level (Linux problem). + * If shared is set, we cause a zero PID->TID load. + * Many of these bits are software only. Bits we don't set + * here we (properly should) assume have the appropriate value. + */ + li r12, 0x0ce2 + andc r11, r11, r12 /* Make sure 20, 21 are zero */ + + /* find the TLB index that caused the fault. It has to be here. + */ + tlbsx r9, 0, r10 + + tlbwe r11, r9, TLB_DATA /* Load TLB LO */ + + /* Done...restore registers and get out of here. + */ +#ifdef CONFIG_403GCX + lwz r12, 12(r0) + lwz r11, 8(r0) + mtspr SPRN_PID, r12 + mtcr r11 + lwz r9, 4(r0) + lwz r12, 0(r0) +#else + mfspr r12, SPRN_SPRG6 + mfspr r11, SPRN_SPRG7 + mtspr SPRN_PID, r12 + mtcr r11 + mfspr r9, SPRN_SPRG5 + mfspr r12, SPRN_SPRG4 +#endif + mfspr r11, SPRN_SPRG1 + mfspr r10, SPRN_SPRG0 + PPC405_ERR77_SYNC + rfi /* Should sync shadow TLBs */ + b . /* prevent prefetch past rfi */ + +2: + /* The bailout. Restore registers to pre-exception conditions + * and call the heavyweights to help us out. + */ +#ifdef CONFIG_403GCX + lwz r12, 12(r0) + lwz r11, 8(r0) + mtspr SPRN_PID, r12 + mtcr r11 + lwz r9, 4(r0) + lwz r12, 0(r0) +#else + mfspr r12, SPRN_SPRG6 + mfspr r11, SPRN_SPRG7 + mtspr SPRN_PID, r12 + mtcr r11 + mfspr r9, SPRN_SPRG5 + mfspr r12, SPRN_SPRG4 +#endif + mfspr r11, SPRN_SPRG1 + mfspr r10, SPRN_SPRG0 + b DataAccess + +/* + * 0x0400 - Instruction Storage Exception + * This is caused by a fetch from non-execute or guarded pages. + */ + START_EXCEPTION(0x0400, InstructionAccess) + NORMAL_EXCEPTION_PROLOG + mr r4,r12 /* Pass SRR0 as arg2 */ + li r5,0 /* Pass zero as arg3 */ + EXC_XFER_EE_LITE(0x400, handle_page_fault) + +/* 0x0500 - External Interrupt Exception */ + EXCEPTION(0x0500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE) + +/* 0x0600 - Alignment Exception */ + START_EXCEPTION(0x0600, Alignment) + NORMAL_EXCEPTION_PROLOG + mfspr r4,SPRN_DEAR /* Grab the DEAR and save it */ + stw r4,_DEAR(r11) + addi r3,r1,STACK_FRAME_OVERHEAD + EXC_XFER_EE(0x600, AlignmentException) + +/* 0x0700 - Program Exception */ + START_EXCEPTION(0x0700, ProgramCheck) + NORMAL_EXCEPTION_PROLOG + mfspr r4,SPRN_ESR /* Grab the ESR and save it */ + stw r4,_ESR(r11) + addi r3,r1,STACK_FRAME_OVERHEAD + EXC_XFER_STD(0x700, ProgramCheckException) + + EXCEPTION(0x0800, Trap_08, UnknownException, EXC_XFER_EE) + EXCEPTION(0x0900, Trap_09, UnknownException, EXC_XFER_EE) + EXCEPTION(0x0A00, Trap_0A, UnknownException, EXC_XFER_EE) + EXCEPTION(0x0B00, Trap_0B, UnknownException, EXC_XFER_EE) + +/* 0x0C00 - System Call Exception */ + START_EXCEPTION(0x0C00, SystemCall) + NORMAL_EXCEPTION_PROLOG + EXC_XFER_EE_LITE(0xc00, DoSyscall) + + EXCEPTION(0x0D00, Trap_0D, UnknownException, EXC_XFER_EE) + EXCEPTION(0x0E00, Trap_0E, UnknownException, EXC_XFER_EE) + EXCEPTION(0x0F00, Trap_0F, UnknownException, EXC_XFER_EE) + +/* 0x1000 - Programmable Interval Timer (PIT) Exception */ + START_EXCEPTION(0x1000, Decrementer) + NORMAL_EXCEPTION_PROLOG + lis r0,TSR_PIS@h + mtspr SPRN_TSR,r0 /* Clear the PIT exception */ + addi r3,r1,STACK_FRAME_OVERHEAD + EXC_XFER_LITE(0x1000, timer_interrupt) + +#if 0 +/* NOTE: + * FIT and WDT handlers are not implemented yet. + */ + +/* 0x1010 - Fixed Interval Timer (FIT) Exception +*/ + STND_EXCEPTION(0x1010, FITException, UnknownException) + +/* 0x1020 - Watchdog Timer (WDT) Exception +*/ + + CRITICAL_EXCEPTION(0x1020, WDTException, UnknownException) +#endif + +/* 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_SPRG0, r10 /* Save some working registers */ + mtspr SPRN_SPRG1, r11 +#ifdef CONFIG_403GCX + stw r12, 0(r0) + stw r9, 4(r0) + mfcr r11 + mfspr r12, SPRN_PID + stw r11, 8(r0) + stw r12, 12(r0) +#else + mtspr SPRN_SPRG4, r12 + mtspr SPRN_SPRG5, r9 + mfcr r11 + mfspr r12, SPRN_PID + mtspr SPRN_SPRG7, r11 + mtspr SPRN_SPRG6, r12 +#endif + mfspr r10, SPRN_DEAR /* Get faulting address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + andis. r11, r10, 0x8000 + beq 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_SPRG3 + lwz r11,PGDIR(r11) +4: + tophys(r11, r11) + rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ + lwz r12, 0(r11) /* Get L1 entry */ + andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */ + beq 2f /* Bail if no table */ + + rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */ + lwz r11, 0(r12) /* Get Linux PTE */ + andi. r9, r11, _PAGE_PRESENT + beq 5f + + ori r11, r11, _PAGE_ACCESSED + stw r11, 0(r12) + + /* Create TLB tag. This is the faulting address plus a static + * set of bits. These are size, valid, E, U0. + */ + li r12, 0x00c0 + rlwimi r10, r12, 0, 20, 31 + + b finish_tlb_load + +2: /* Check for possible large-page pmd entry */ + rlwinm. r9, r12, 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 + mr r11, r12 + + b finish_tlb_load + +5: + /* The bailout. Restore registers to pre-exception conditions + * and call the heavyweights to help us out. + */ +#ifdef CONFIG_403GCX + lwz r12, 12(r0) + lwz r11, 8(r0) + mtspr SPRN_PID, r12 + mtcr r11 + lwz r9, 4(r0) + lwz r12, 0(r0) +#else + mfspr r12, SPRN_SPRG6 + mfspr r11, SPRN_SPRG7 + mtspr SPRN_PID, r12 + mtcr r11 + mfspr r9, SPRN_SPRG5 + mfspr r12, SPRN_SPRG4 +#endif + mfspr r11, SPRN_SPRG1 + mfspr r10, SPRN_SPRG0 + b DataAccess + +/* 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_SPRG0, r10 /* Save some working registers */ + mtspr SPRN_SPRG1, r11 +#ifdef CONFIG_403GCX + stw r12, 0(r0) + stw r9, 4(r0) + mfcr r11 + mfspr r12, SPRN_PID + stw r11, 8(r0) + stw r12, 12(r0) +#else + mtspr SPRN_SPRG4, r12 + mtspr SPRN_SPRG5, r9 + mfcr r11 + mfspr r12, SPRN_PID + mtspr SPRN_SPRG7, r11 + mtspr SPRN_SPRG6, r12 +#endif + mfspr r10, SPRN_SRR0 /* Get faulting address */ + + /* If we are faulting a kernel address, we have to use the + * kernel page tables. + */ + andis. r11, r10, 0x8000 + beq 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_SPRG3 + lwz r11,PGDIR(r11) +4: + tophys(r11, r11) + rlwimi r11, r10, 12, 20, 29 /* Create L1 (pgdir/pmd) address */ + lwz r12, 0(r11) /* Get L1 entry */ + andi. r9, r12, _PMD_PRESENT /* Check if it points to a PTE page */ + beq 2f /* Bail if no table */ + + rlwimi r12, r10, 22, 20, 29 /* Compute PTE address */ + lwz r11, 0(r12) /* Get Linux PTE */ + andi. r9, r11, _PAGE_PRESENT + beq 5f + + ori r11, r11, _PAGE_ACCESSED + stw r11, 0(r12) + + /* Create TLB tag. This is the faulting address plus a static + * set of bits. These are size, valid, E, U0. + */ + li r12, 0x00c0 + rlwimi r10, r12, 0, 20, 31 + + b finish_tlb_load + +2: /* Check for possible large-page pmd entry */ + rlwinm. r9, r12, 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 + mr r11, r12 + + b finish_tlb_load + +5: + /* The bailout. Restore registers to pre-exception conditions + * and call the heavyweights to help us out. + */ +#ifdef CONFIG_403GCX + lwz r12, 12(r0) + lwz r11, 8(r0) + mtspr SPRN_PID, r12 + mtcr r11 + lwz r9, 4(r0) + lwz r12, 0(r0) +#else + mfspr r12, SPRN_SPRG6 + mfspr r11, SPRN_SPRG7 + mtspr SPRN_PID, r12 + mtcr r11 + mfspr r9, SPRN_SPRG5 + mfspr r12, SPRN_SPRG4 +#endif + mfspr r11, SPRN_SPRG1 + mfspr r10, SPRN_SPRG0 + b InstructionAccess + + EXCEPTION(0x1300, Trap_13, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1400, Trap_14, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1500, Trap_15, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1600, Trap_16, UnknownException, EXC_XFER_EE) +#ifdef CONFIG_IBM405_ERR51 + /* 405GP errata 51 */ + START_EXCEPTION(0x1700, Trap_17) + b DTLBMiss +#else + EXCEPTION(0x1700, Trap_17, UnknownException, EXC_XFER_EE) +#endif + EXCEPTION(0x1800, Trap_18, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1900, Trap_19, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1A00, Trap_1A, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1B00, Trap_1B, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1C00, Trap_1C, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1D00, Trap_1D, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1E00, Trap_1E, UnknownException, EXC_XFER_EE) + EXCEPTION(0x1F00, Trap_1F, UnknownException, EXC_XFER_EE) + +/* 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 + + /* + * 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) + PPC405_ERR77_SYNC + rfci + b . + + /* continue normal handling for a critical exception... */ +2: mfspr r4,SPRN_DBSR + addi r3,r1,STACK_FRAME_OVERHEAD + EXC_XFER_TEMPLATE(DebugException, 0x2002, \ + (MSR_KERNEL & ~(MSR_ME|MSR_DE|MSR_CE)), \ + NOCOPY, crit_transfer_to_handler, ret_from_crit_exc) + +/* + * The other Data TLB exceptions bail out to this point + * if they can't resolve the lightweight TLB fault. + */ +DataAccess: + NORMAL_EXCEPTION_PROLOG + mfspr r5,SPRN_ESR /* Grab the ESR, save it, pass arg3 */ + stw r5,_ESR(r11) + mfspr r4,SPRN_DEAR /* Grab the DEAR, save it, pass arg2 */ + EXC_XFER_EE_LITE(0x300, handle_page_fault) + +/* 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. + */ + + /* 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 + * r12, r9 - avilable 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: + /* load the next available TLB index. + */ + lwz r9, tlb_4xx_index@l(0) + addi r9, r9, 1 + andi. r9, r9, (PPC4XX_TLB_SIZE-1) + stw r9, tlb_4xx_index@l(0) + +6: + /* + * 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 r12, 0x0ce2 + andc r11, r11, r12 + + tlbwe r11, r9, TLB_DATA /* Load TLB LO */ + tlbwe r10, r9, TLB_TAG /* Load TLB HI */ + + /* Done...restore registers and get out of here. + */ +#ifdef CONFIG_403GCX + lwz r12, 12(r0) + lwz r11, 8(r0) + mtspr SPRN_PID, r12 + mtcr r11 + lwz r9, 4(r0) + lwz r12, 0(r0) +#else + mfspr r12, SPRN_SPRG6 + mfspr r11, SPRN_SPRG7 + mtspr SPRN_PID, r12 + mtcr r11 + mfspr r9, SPRN_SPRG5 + mfspr r12, SPRN_SPRG4 +#endif + mfspr r11, SPRN_SPRG1 + mfspr r10, SPRN_SPRG0 + PPC405_ERR77_SYNC + rfi /* Should sync shadow TLBs */ + b . /* prevent prefetch past rfi */ + +/* extern void giveup_fpu(struct task_struct *prev) + * + * The PowerPC 4xx family of processors do not have an FPU, so this just + * returns. + */ +_GLOBAL(giveup_fpu) + 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 + + /* ptr to phys current thread */ + tophys(r4,r2) + addi r4,r4,THREAD /* init task's THREAD */ + mtspr SPRN_SPRG3,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. + */ + 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 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(r0) /* 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 16 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 two entries into TLB slots 62 and 63. + * In case we are pinning TLBs, these are reserved in by the + * other TLB functions. If not reserving, then it doesn't + * matter where they are loaded. + */ + 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 */ + +#if defined(CONFIG_SERIAL_TEXT_DEBUG) && defined(SERIAL_DEBUG_IO_BASE) + + /* Load a TLB entry for the UART, so that ppc4xx_progress() can use + * the UARTs nice and early. We use a 4k real==virtual mapping. */ + + lis r3,SERIAL_DEBUG_IO_BASE@h + ori r3,r3,SERIAL_DEBUG_IO_BASE@l + mr r4,r3 + clrrwi r4,r4,12 + ori r4,r4,(TLB_WR|TLB_I|TLB_M|TLB_G) + + clrrwi r3,r3,12 + ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_4K)) + + li r0,0 /* TLB slot 0 */ + tlbwe r4,r0,TLB_DATA + tlbwe r3,r0,TLB_TAG +#endif /* CONFIG_SERIAL_DEBUG_TEXT && SERIAL_DEBUG_IO_BASE */ + + 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 + +_GLOBAL(set_context) + +#ifdef CONFIG_BDI_SWITCH + /* Context switch the PTE pointer for the Abatron BDI2000. + * The PGDIR is the second parameter. + */ + lis r5, KERNELBASE@h + lwz r5, 0xf0(r5) + stw r4, 0x4(r5) +#endif + sync + mtspr SPRN_PID,r3 + isync /* Need an isync to flush shadow */ + /* TLBs after changing PID */ + 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 +_GLOBAL(sdata) +_GLOBAL(empty_zero_page) + .space 4096 +_GLOBAL(swapper_pg_dir) + .space 4096 + + +/* Stack for handling critical exceptions from kernel mode */ + .section .bss + .align 12 +exception_stack_bottom: + .space 4096 +critical_stack_top: +_GLOBAL(exception_stack_top) + +/* This space gets a copy of optional info passed to us by the bootstrap + * which is used to pass parameters into the kernel like root=/dev/sda1, etc. + */ +_GLOBAL(cmd_line) + .space 512 + +/* Room for two PTE pointers, usually the kernel and current user pointers + * to their respective root page table. + */ +abatron_pteptrs: + .space 8 |