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ee43eb788b
The kernel uses SPRG registers for various purposes, typically in low level assembly code as scratch registers or to hold per-cpu global infos such as the PACA or the current thread_info pointer. We want to be able to easily shuffle the usage of those registers as some implementations have specific constraints realted to some of them, for example, some have userspace readable aliases, etc.. and the current choice isn't always the best. This patch should not change any code generation, and replaces the usage of SPRN_SPRGn everywhere in the kernel with a named replacement and adds documentation next to the definition of the names as to what those are used for on each processor family. The only parts that still use the original numbers are bits of KVM or suspend/resume code that just blindly needs to save/restore all the SPRGs. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
882 lines
25 KiB
ArmAsm
882 lines
25 KiB
ArmAsm
/*
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* PowerPC version
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* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
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* Rewritten by Cort Dougan (cort@cs.nmt.edu) for PReP
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* Copyright (C) 1996 Cort Dougan <cort@cs.nmt.edu>
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* Low-level exception handlers and MMU support
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* rewritten by Paul Mackerras.
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* Copyright (C) 1996 Paul Mackerras.
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* MPC8xx modifications by Dan Malek
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* Copyright (C) 1997 Dan Malek (dmalek@jlc.net).
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*
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* This file contains low-level support and setup for PowerPC 8xx
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* embedded processors, including trap and interrupt dispatch.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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*/
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#include <linux/init.h>
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#include <asm/processor.h>
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#include <asm/page.h>
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#include <asm/mmu.h>
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#include <asm/cache.h>
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#include <asm/pgtable.h>
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#include <asm/cputable.h>
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#include <asm/thread_info.h>
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#include <asm/ppc_asm.h>
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#include <asm/asm-offsets.h>
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/* Macro to make the code more readable. */
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#ifdef CONFIG_8xx_CPU6
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#define DO_8xx_CPU6(val, reg) \
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li reg, val; \
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stw reg, 12(r0); \
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lwz reg, 12(r0);
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#else
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#define DO_8xx_CPU6(val, reg)
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#endif
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__HEAD
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_ENTRY(_stext);
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_ENTRY(_start);
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/* MPC8xx
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* This port was done on an MBX board with an 860. Right now I only
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* support an ELF compressed (zImage) boot from EPPC-Bug because the
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* code there loads up some registers before calling us:
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* r3: ptr to board info data
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* r4: initrd_start or if no initrd then 0
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* r5: initrd_end - unused if r4 is 0
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* r6: Start of command line string
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* r7: End of command line string
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*
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* I decided to use conditional compilation instead of checking PVR and
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* adding more processor specific branches around code I don't need.
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* Since this is an embedded processor, I also appreciate any memory
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* savings I can get.
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*
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* The MPC8xx does not have any BATs, but it supports large page sizes.
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* We first initialize the MMU to support 8M byte pages, then load one
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* entry into each of the instruction and data TLBs to map the first
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* 8M 1:1. I also mapped an additional I/O space 1:1 so we can get to
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* the "internal" processor registers before MMU_init is called.
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*
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* The TLB code currently contains a major hack. Since I use the condition
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* code register, I have to save and restore it. I am out of registers, so
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* I just store it in memory location 0 (the TLB handlers are not reentrant).
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* To avoid making any decisions, I need to use the "segment" valid bit
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* in the first level table, but that would require many changes to the
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* Linux page directory/table functions that I don't want to do right now.
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*
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* I used to use SPRG2 for a temporary register in the TLB handler, but it
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* has since been put to other uses. I now use a hack to save a register
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* and the CCR at memory location 0.....Someday I'll fix this.....
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* -- Dan
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*/
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.globl __start
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__start:
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mr r31,r3 /* save parameters */
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mr r30,r4
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mr r29,r5
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mr r28,r6
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mr r27,r7
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/* We have to turn on the MMU right away so we get cache modes
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* set correctly.
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*/
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bl initial_mmu
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/* We now have the lower 8 Meg mapped into TLB entries, and the caches
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* ready to work.
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*/
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turn_on_mmu:
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mfmsr r0
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ori r0,r0,MSR_DR|MSR_IR
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mtspr SPRN_SRR1,r0
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lis r0,start_here@h
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ori r0,r0,start_here@l
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mtspr SPRN_SRR0,r0
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SYNC
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rfi /* enables MMU */
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/*
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* Exception entry code. This code runs with address translation
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* turned off, i.e. using physical addresses.
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* We assume sprg3 has the physical address of the current
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* task's thread_struct.
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*/
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#define EXCEPTION_PROLOG \
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mtspr SPRN_SPRG_SCRATCH0,r10; \
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mtspr SPRN_SPRG_SCRATCH1,r11; \
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mfcr r10; \
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EXCEPTION_PROLOG_1; \
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EXCEPTION_PROLOG_2
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#define EXCEPTION_PROLOG_1 \
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mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \
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andi. r11,r11,MSR_PR; \
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tophys(r11,r1); /* use tophys(r1) if kernel */ \
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beq 1f; \
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mfspr r11,SPRN_SPRG_THREAD; \
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lwz r11,THREAD_INFO-THREAD(r11); \
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addi r11,r11,THREAD_SIZE; \
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tophys(r11,r11); \
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1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */
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#define EXCEPTION_PROLOG_2 \
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CLR_TOP32(r11); \
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stw r10,_CCR(r11); /* save registers */ \
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stw r12,GPR12(r11); \
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stw r9,GPR9(r11); \
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mfspr r10,SPRN_SPRG_SCRATCH0; \
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stw r10,GPR10(r11); \
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mfspr r12,SPRN_SPRG_SCRATCH1; \
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stw r12,GPR11(r11); \
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mflr r10; \
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stw r10,_LINK(r11); \
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mfspr r12,SPRN_SRR0; \
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mfspr r9,SPRN_SRR1; \
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stw r1,GPR1(r11); \
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stw r1,0(r11); \
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tovirt(r1,r11); /* set new kernel sp */ \
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li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \
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MTMSRD(r10); /* (except for mach check in rtas) */ \
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stw r0,GPR0(r11); \
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SAVE_4GPRS(3, r11); \
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SAVE_2GPRS(7, r11)
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/*
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* Note: code which follows this uses cr0.eq (set if from kernel),
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* r11, r12 (SRR0), and r9 (SRR1).
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*
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* Note2: once we have set r1 we are in a position to take exceptions
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* again, and we could thus set MSR:RI at that point.
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*/
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/*
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* Exception vectors.
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*/
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#define EXCEPTION(n, label, hdlr, xfer) \
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. = n; \
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label: \
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EXCEPTION_PROLOG; \
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addi r3,r1,STACK_FRAME_OVERHEAD; \
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xfer(n, hdlr)
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#define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \
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li r10,trap; \
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stw r10,_TRAP(r11); \
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li r10,MSR_KERNEL; \
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copyee(r10, r9); \
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bl tfer; \
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i##n: \
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.long hdlr; \
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.long ret
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#define COPY_EE(d, s) rlwimi d,s,0,16,16
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#define NOCOPY(d, s)
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#define EXC_XFER_STD(n, hdlr) \
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EXC_XFER_TEMPLATE(n, hdlr, n, NOCOPY, transfer_to_handler_full, \
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ret_from_except_full)
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#define EXC_XFER_LITE(n, hdlr) \
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EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \
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ret_from_except)
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#define EXC_XFER_EE(n, hdlr) \
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EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \
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ret_from_except_full)
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#define EXC_XFER_EE_LITE(n, hdlr) \
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EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \
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ret_from_except)
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/* System reset */
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EXCEPTION(0x100, Reset, unknown_exception, EXC_XFER_STD)
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/* Machine check */
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. = 0x200
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MachineCheck:
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EXCEPTION_PROLOG
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mfspr r4,SPRN_DAR
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stw r4,_DAR(r11)
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mfspr r5,SPRN_DSISR
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stw r5,_DSISR(r11)
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addi r3,r1,STACK_FRAME_OVERHEAD
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EXC_XFER_STD(0x200, machine_check_exception)
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/* Data access exception.
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* This is "never generated" by the MPC8xx. We jump to it for other
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* translation errors.
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*/
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. = 0x300
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DataAccess:
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EXCEPTION_PROLOG
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mfspr r10,SPRN_DSISR
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stw r10,_DSISR(r11)
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mr r5,r10
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mfspr r4,SPRN_DAR
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EXC_XFER_EE_LITE(0x300, handle_page_fault)
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/* Instruction access exception.
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* This is "never generated" by the MPC8xx. We jump to it for other
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* translation errors.
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*/
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. = 0x400
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InstructionAccess:
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EXCEPTION_PROLOG
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mr r4,r12
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mr r5,r9
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EXC_XFER_EE_LITE(0x400, handle_page_fault)
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/* External interrupt */
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EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
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/* Alignment exception */
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. = 0x600
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Alignment:
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EXCEPTION_PROLOG
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mfspr r4,SPRN_DAR
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stw r4,_DAR(r11)
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mfspr r5,SPRN_DSISR
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stw r5,_DSISR(r11)
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addi r3,r1,STACK_FRAME_OVERHEAD
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EXC_XFER_EE(0x600, alignment_exception)
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/* Program check exception */
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EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
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/* No FPU on MPC8xx. This exception is not supposed to happen.
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*/
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EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
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/* Decrementer */
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EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
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EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE)
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EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE)
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/* System call */
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. = 0xc00
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SystemCall:
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EXCEPTION_PROLOG
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EXC_XFER_EE_LITE(0xc00, DoSyscall)
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/* Single step - not used on 601 */
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EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
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EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE)
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EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE)
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/* On the MPC8xx, this is a software emulation interrupt. It occurs
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* for all unimplemented and illegal instructions.
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*/
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EXCEPTION(0x1000, SoftEmu, SoftwareEmulation, EXC_XFER_STD)
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. = 0x1100
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/*
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* For the MPC8xx, this is a software tablewalk to load the instruction
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* TLB. It is modelled after the example in the Motorola manual. The task
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* switch loads the M_TWB register with the pointer to the first level table.
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* If we discover there is no second level table (value is zero) or if there
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* is an invalid pte, we load that into the TLB, which causes another fault
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* into the TLB Error interrupt where we can handle such problems.
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* We have to use the MD_xxx registers for the tablewalk because the
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* equivalent MI_xxx registers only perform the attribute functions.
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*/
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InstructionTLBMiss:
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#ifdef CONFIG_8xx_CPU6
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stw r3, 8(r0)
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#endif
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DO_8xx_CPU6(0x3f80, r3)
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mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
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mfcr r10
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stw r10, 0(r0)
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stw r11, 4(r0)
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mfspr r10, SPRN_SRR0 /* Get effective address of fault */
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#ifdef CONFIG_8xx_CPU15
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addi r11, r10, 0x1000
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tlbie r11
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addi r11, r10, -0x1000
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tlbie r11
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#endif
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DO_8xx_CPU6(0x3780, r3)
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mtspr SPRN_MD_EPN, r10 /* Have to use MD_EPN for walk, MI_EPN can't */
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mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */
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/* If we are faulting a kernel address, we have to use the
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* kernel page tables.
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*/
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andi. r11, r10, 0x0800 /* Address >= 0x80000000 */
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beq 3f
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lis r11, swapper_pg_dir@h
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ori r11, r11, swapper_pg_dir@l
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rlwimi r10, r11, 0, 2, 19
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3:
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lwz r11, 0(r10) /* Get the level 1 entry */
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rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
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beq 2f /* If zero, don't try to find a pte */
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/* We have a pte table, so load the MI_TWC with the attributes
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* for this "segment."
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*/
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ori r11,r11,1 /* Set valid bit */
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DO_8xx_CPU6(0x2b80, r3)
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mtspr SPRN_MI_TWC, r11 /* Set segment attributes */
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DO_8xx_CPU6(0x3b80, r3)
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mtspr SPRN_MD_TWC, r11 /* Load pte table base address */
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mfspr r11, SPRN_MD_TWC /* ....and get the pte address */
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lwz r10, 0(r11) /* Get the pte */
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#ifdef CONFIG_SWAP
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/* do not set the _PAGE_ACCESSED bit of a non-present page */
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andi. r11, r10, _PAGE_PRESENT
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beq 4f
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ori r10, r10, _PAGE_ACCESSED
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mfspr r11, SPRN_MD_TWC /* get the pte address again */
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stw r10, 0(r11)
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4:
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#else
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ori r10, r10, _PAGE_ACCESSED
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stw r10, 0(r11)
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#endif
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/* The Linux PTE won't go exactly into the MMU TLB.
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* Software indicator bits 21, 22 and 28 must be clear.
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* Software indicator bits 24, 25, 26, and 27 must be
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* set. All other Linux PTE bits control the behavior
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* of the MMU.
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*/
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2: li r11, 0x00f0
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rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
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DO_8xx_CPU6(0x2d80, r3)
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mtspr SPRN_MI_RPN, r10 /* Update TLB entry */
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mfspr r10, SPRN_M_TW /* Restore registers */
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lwz r11, 0(r0)
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mtcr r11
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lwz r11, 4(r0)
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#ifdef CONFIG_8xx_CPU6
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lwz r3, 8(r0)
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#endif
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rfi
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. = 0x1200
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DataStoreTLBMiss:
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#ifdef CONFIG_8xx_CPU6
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stw r3, 8(r0)
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#endif
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DO_8xx_CPU6(0x3f80, r3)
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mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
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mfcr r10
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stw r10, 0(r0)
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stw r11, 4(r0)
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mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */
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/* If we are faulting a kernel address, we have to use the
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* kernel page tables.
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*/
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andi. r11, r10, 0x0800
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beq 3f
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lis r11, swapper_pg_dir@h
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ori r11, r11, swapper_pg_dir@l
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rlwimi r10, r11, 0, 2, 19
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3:
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lwz r11, 0(r10) /* Get the level 1 entry */
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rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
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beq 2f /* If zero, don't try to find a pte */
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/* We have a pte table, so load fetch the pte from the table.
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*/
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ori r11, r11, 1 /* Set valid bit in physical L2 page */
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DO_8xx_CPU6(0x3b80, r3)
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mtspr SPRN_MD_TWC, r11 /* Load pte table base address */
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mfspr r10, SPRN_MD_TWC /* ....and get the pte address */
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lwz r10, 0(r10) /* Get the pte */
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/* Insert the Guarded flag into the TWC from the Linux PTE.
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* It is bit 27 of both the Linux PTE and the TWC (at least
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* I got that right :-). It will be better when we can put
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* this into the Linux pgd/pmd and load it in the operation
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* above.
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*/
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rlwimi r11, r10, 0, 27, 27
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DO_8xx_CPU6(0x3b80, r3)
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mtspr SPRN_MD_TWC, r11
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#ifdef CONFIG_SWAP
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/* do not set the _PAGE_ACCESSED bit of a non-present page */
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andi. r11, r10, _PAGE_PRESENT
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beq 4f
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ori r10, r10, _PAGE_ACCESSED
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4:
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/* and update pte in table */
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#else
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ori r10, r10, _PAGE_ACCESSED
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#endif
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mfspr r11, SPRN_MD_TWC /* get the pte address again */
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stw r10, 0(r11)
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/* The Linux PTE won't go exactly into the MMU TLB.
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* Software indicator bits 21, 22 and 28 must be clear.
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* Software indicator bits 24, 25, 26, and 27 must be
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* set. All other Linux PTE bits control the behavior
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* of the MMU.
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*/
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2: li r11, 0x00f0
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rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
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DO_8xx_CPU6(0x3d80, r3)
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mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
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mfspr r10, SPRN_M_TW /* Restore registers */
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lwz r11, 0(r0)
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mtcr r11
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lwz r11, 4(r0)
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|
#ifdef CONFIG_8xx_CPU6
|
|
lwz r3, 8(r0)
|
|
#endif
|
|
rfi
|
|
|
|
/* 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)
|
|
#endif
|
|
DO_8xx_CPU6(0x3f80, r3)
|
|
mtspr SPRN_M_TW, r10 /* Save a couple of working registers */
|
|
mfcr r10
|
|
stw r10, 0(r0)
|
|
stw r11, 4(r0)
|
|
|
|
/* First, make sure this was a store operation.
|
|
*/
|
|
mfspr r10, SPRN_DSISR
|
|
andis. r11, r10, 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 r10, SPRN_DAR
|
|
rlwinm r11, r10, 0, 0, 19
|
|
ori r11, r11, MD_EVALID
|
|
mfspr r10, SPRN_M_CASID
|
|
rlwimi r11, r10, 0, 28, 31
|
|
DO_8xx_CPU6(0x3780, r3)
|
|
mtspr SPRN_MD_EPN, r11
|
|
|
|
mfspr r10, SPRN_M_TWB /* Get level 1 table entry address */
|
|
|
|
/* If we are faulting a kernel address, we have to use the
|
|
* kernel page tables.
|
|
*/
|
|
andi. r11, r10, 0x0800
|
|
beq 3f
|
|
lis r11, swapper_pg_dir@h
|
|
ori r11, r11, swapper_pg_dir@l
|
|
rlwimi r10, r11, 0, 2, 19
|
|
3:
|
|
lwz r11, 0(r10) /* Get the level 1 entry */
|
|
rlwinm. r10, r11,0,0,19 /* Extract page descriptor page address */
|
|
beq 2f /* If zero, bail */
|
|
|
|
/* We have a pte table, so fetch the pte from the table.
|
|
*/
|
|
ori r11, r11, 1 /* Set valid bit in physical L2 page */
|
|
DO_8xx_CPU6(0x3b80, r3)
|
|
mtspr SPRN_MD_TWC, r11 /* Load pte table base address */
|
|
mfspr r11, SPRN_MD_TWC /* ....and get the pte address */
|
|
lwz r10, 0(r11) /* Get the pte */
|
|
|
|
andi. r11, r10, _PAGE_RW /* Is it writeable? */
|
|
beq 2f /* Bail out if not */
|
|
|
|
/* Update 'changed', among others.
|
|
*/
|
|
#ifdef CONFIG_SWAP
|
|
ori r10, r10, _PAGE_DIRTY|_PAGE_HWWRITE
|
|
/* do not set the _PAGE_ACCESSED bit of a non-present page */
|
|
andi. r11, r10, _PAGE_PRESENT
|
|
beq 4f
|
|
ori r10, r10, _PAGE_ACCESSED
|
|
4:
|
|
#else
|
|
ori r10, r10, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
|
|
#endif
|
|
mfspr r11, SPRN_MD_TWC /* Get pte address again */
|
|
stw r10, 0(r11) /* 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 r11, 0x00f0
|
|
rlwimi r10, r11, 0, 24, 28 /* Set 24-27, clear 28 */
|
|
DO_8xx_CPU6(0x3d80, r3)
|
|
mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
|
|
|
|
mfspr r10, SPRN_M_TW /* Restore registers */
|
|
lwz r11, 0(r0)
|
|
mtcr r11
|
|
lwz r11, 4(r0)
|
|
#ifdef CONFIG_8xx_CPU6
|
|
lwz r3, 8(r0)
|
|
#endif
|
|
rfi
|
|
2:
|
|
mfspr r10, SPRN_M_TW /* Restore registers */
|
|
lwz r11, 0(r0)
|
|
mtcr r11
|
|
lwz r11, 4(r0)
|
|
#ifdef CONFIG_8xx_CPU6
|
|
lwz r3, 8(r0)
|
|
#endif
|
|
b DataAccess
|
|
|
|
EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1800, Trap_18, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1900, Trap_19, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1a00, Trap_1a, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1b00, Trap_1b, unknown_exception, EXC_XFER_EE)
|
|
|
|
/* On the MPC8xx, these next four traps are used for development
|
|
* support of breakpoints and such. Someday I will get around to
|
|
* using them.
|
|
*/
|
|
EXCEPTION(0x1c00, Trap_1c, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE)
|
|
EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE)
|
|
|
|
. = 0x2000
|
|
|
|
.globl giveup_fpu
|
|
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_SPRG_THREAD,r4
|
|
li r3,0
|
|
/* XXX What is that for ? SPRG2 appears otherwise unused on 8xx */
|
|
mtspr SPRN_SPRG2,r3 /* 0 => r1 has kernel sp */
|
|
|
|
/* 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 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 SPRN_M_TWB, r6
|
|
lis r4,2f@h
|
|
ori r4,r4,2f@l
|
|
tophys(r4,r4)
|
|
li r3,MSR_KERNEL & ~(MSR_IR|MSR_DR)
|
|
mtspr SPRN_SRR0,r4
|
|
mtspr SPRN_SRR1,r3
|
|
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 */
|
|
|
|
/* set up the PTE pointers for the Abatron bdiGDB.
|
|
*/
|
|
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)
|
|
|
|
/* Now turn on the MMU for real! */
|
|
li r4,MSR_KERNEL
|
|
lis r3,start_kernel@h
|
|
ori r3,r3,start_kernel@l
|
|
mtspr SPRN_SRR0,r3
|
|
mtspr SPRN_SRR1,r4
|
|
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).
|
|
* If configured to pin some TLBs, we pin the first 8 Mbytes of kernel,
|
|
* 24 Mbytes of data, and the 8M IMMR space. Anything not covered by
|
|
* these mappings is mapped by page tables.
|
|
*/
|
|
initial_mmu:
|
|
tlbia /* Invalidate all TLB entries */
|
|
#ifdef CONFIG_PIN_TLB
|
|
lis r8, MI_RSV4I@h
|
|
ori r8, r8, 0x1c00
|
|
#else
|
|
li r8, 0
|
|
#endif
|
|
mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
|
|
|
|
#ifdef CONFIG_PIN_TLB
|
|
lis r10, (MD_RSV4I | MD_RESETVAL)@h
|
|
ori r10, r10, 0x1c00
|
|
mr r8, r10
|
|
#else
|
|
lis r10, MD_RESETVAL@h
|
|
#endif
|
|
#ifndef CONFIG_8xx_COPYBACK
|
|
oris r10, r10, MD_WTDEF@h
|
|
#endif
|
|
mtspr SPRN_MD_CTR, r10 /* 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 SPRN_MI_EPN, r8
|
|
mtspr SPRN_MD_EPN, r8
|
|
li r8, MI_PS8MEG /* Set 8M byte page */
|
|
ori r8, r8, MI_SVALID /* Make it valid */
|
|
mtspr SPRN_MI_TWC, r8
|
|
mtspr SPRN_MD_TWC, r8
|
|
li r8, MI_BOOTINIT /* Create RPN for address 0 */
|
|
mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
|
|
mtspr SPRN_MD_RPN, r8
|
|
lis r8, MI_Kp@h /* Set the protection mode */
|
|
mtspr SPRN_MI_AP, r8
|
|
mtspr SPRN_MD_AP, r8
|
|
|
|
/* Map another 8 MByte at the IMMR to get the processor
|
|
* internal registers (among other things).
|
|
*/
|
|
#ifdef CONFIG_PIN_TLB
|
|
addi r10, r10, 0x0100
|
|
mtspr SPRN_MD_CTR, r10
|
|
#endif
|
|
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 SPRN_MD_EPN, r8
|
|
li r8, MD_PS8MEG /* Set 8M byte page */
|
|
ori r8, r8, MD_SVALID /* Make it valid */
|
|
mtspr SPRN_MD_TWC, r8
|
|
mr r8, r9 /* Create paddr for TLB */
|
|
ori r8, r8, MI_BOOTINIT|0x2 /* Inhibit cache -- Cort */
|
|
mtspr SPRN_MD_RPN, r8
|
|
|
|
#ifdef CONFIG_PIN_TLB
|
|
/* Map two more 8M kernel data pages.
|
|
*/
|
|
addi r10, r10, 0x0100
|
|
mtspr SPRN_MD_CTR, r10
|
|
|
|
lis r8, KERNELBASE@h /* Create vaddr for TLB */
|
|
addis r8, r8, 0x0080 /* Add 8M */
|
|
ori r8, r8, MI_EVALID /* Mark it valid */
|
|
mtspr SPRN_MD_EPN, r8
|
|
li r9, MI_PS8MEG /* Set 8M byte page */
|
|
ori r9, r9, MI_SVALID /* Make it valid */
|
|
mtspr SPRN_MD_TWC, r9
|
|
li r11, MI_BOOTINIT /* Create RPN for address 0 */
|
|
addis r11, r11, 0x0080 /* Add 8M */
|
|
mtspr SPRN_MD_RPN, r11
|
|
|
|
addis r8, r8, 0x0080 /* Add 8M */
|
|
mtspr SPRN_MD_EPN, r8
|
|
mtspr SPRN_MD_TWC, r9
|
|
addis r11, r11, 0x0080 /* Add 8M */
|
|
mtspr SPRN_MD_RPN, r11
|
|
#endif
|
|
|
|
/* 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 SPRN_IC_CST, r8
|
|
mtspr SPRN_DC_CST, r8
|
|
lis r8, IDC_ENABLE@h
|
|
mtspr SPRN_IC_CST, r8
|
|
#ifdef CONFIG_8xx_COPYBACK
|
|
mtspr SPRN_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 SPRN_DC_CST, r8
|
|
lis r8, IDC_ENABLE@h
|
|
mtspr SPRN_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 SPRN_M_TWB, r4 /* Update MMU base address */
|
|
li r7, 0x3380
|
|
stw r7, 12(r6)
|
|
lwz r7, 12(r6)
|
|
mtspr SPRN_M_CASID, r3 /* Update context */
|
|
#else
|
|
mtspr SPRN_M_CASID,r3 /* Update context */
|
|
tophys (r4, r4)
|
|
mtspr SPRN_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
|
|
|
|
/* Room for two PTE table poiners, usually the kernel and current user
|
|
* pointer to their respective root page table (pgdir).
|
|
*/
|
|
abatron_pteptrs:
|
|
.space 8
|
|
|
|
#ifdef CONFIG_8xx_CPU6
|
|
.globl cpu6_errata_word
|
|
cpu6_errata_word:
|
|
.space 16
|
|
#endif
|
|
|