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linux/arch/powerpc/kernel/head_8xx.S
Christophe Leroy 4f94b2c746 powerpc/8xx: Use L1 entry APG to handle _PAGE_ACCESSED for CONFIG_SWAP 
When CONFIG_SWAP is set, the TLB miss handlers have to also take
into account _PAGE_ACCESSED flag. At the moment it is done by
anding _PAGE_ACCESSED into _PAGE_PRESENT using 3 instructions.

This patch uses APG for handling _PAGE_ACCESSED, allowing to
just copy _PAGE_ACCESSED bit into APG field, hence reducing the
action to a single instruction.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-01-16 23:47:15 +11:00

1065 lines
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/*
* 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 <cort@cs.nmt.edu>
* 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 <linux/init.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/cache.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/ptrace.h>
#include <asm/fixmap.h>
#include <asm/export.h>
#if CONFIG_TASK_SIZE <= 0x80000000 && CONFIG_PAGE_OFFSET >= 0x80000000
/* By simply checking Address >= 0x80000000, we know if its a kernel address */
#define SIMPLE_KERNEL_ADDRESS 1
#endif
/*
* We need an ITLB miss handler for kernel addresses if:
* - Either we have modules
* - Or we have not pinned the first 8M
*/
#if defined(CONFIG_MODULES) || !defined(CONFIG_PIN_TLB_TEXT) || \
defined(CONFIG_DEBUG_PAGEALLOC)
#define ITLB_MISS_KERNEL 1
#endif
/*
* Value for the bits that have fixed value in RPN entries.
* Also used for tagging DAR for DTLBerror.
*/
#define RPN_PATTERN 0x00f0
#define PAGE_SHIFT_512K 19
#define PAGE_SHIFT_8M 23
__HEAD
_ENTRY(_stext);
_ENTRY(_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.
*
* -- Dan
*/
.globl __start
__start:
mr r31,r3 /* save device tree ptr */
/* We have to turn on the MMU right away so we get cache modes
* set correctly.
*/
bl initial_mmu
/* We now have the lower 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 SPRN_SRR1,r0
lis r0,start_here@h
ori r0,r0,start_here@l
mtspr SPRN_SRR0,r0
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 SPRN_SPRG_SCRATCH0, r10; \
mtspr SPRN_SPRG_SCRATCH1, r11; \
mfcr r10; \
EXCEPTION_PROLOG_1; \
EXCEPTION_PROLOG_2
#define EXCEPTION_PROLOG_1 \
mfspr r11,SPRN_SRR1; /* check whether user or kernel */ \
andi. r11,r11,MSR_PR; \
tophys(r11,r1); /* use tophys(r1) if kernel */ \
beq 1f; \
mfspr r11,SPRN_SPRG_THREAD; \
lwz r11,THREAD_INFO-THREAD(r11); \
addi r11,r11,THREAD_SIZE; \
tophys(r11,r11); \
1: subi r11,r11,INT_FRAME_SIZE /* alloc exc. frame */
#define EXCEPTION_PROLOG_2 \
stw r10,_CCR(r11); /* save registers */ \
stw r12,GPR12(r11); \
stw r9,GPR9(r11); \
mfspr r10,SPRN_SPRG_SCRATCH0; \
stw r10,GPR10(r11); \
mfspr r12,SPRN_SPRG_SCRATCH1; \
stw r12,GPR11(r11); \
mflr r10; \
stw r10,_LINK(r11); \
mfspr r12,SPRN_SRR0; \
mfspr r9,SPRN_SRR1; \
stw r1,GPR1(r11); \
stw r1,0(r11); \
tovirt(r1,r11); /* set new kernel sp */ \
li r10,MSR_KERNEL & ~(MSR_IR|MSR_DR); /* can take exceptions */ \
mtmsr r10; \
stw r0,GPR0(r11); \
SAVE_4GPRS(3, r11); \
SAVE_2GPRS(7, r11)
/*
* Note: code which follows this uses cr0.eq (set if from kernel),
* r11, r12 (SRR0), and r9 (SRR1).
*
* Note2: once we have set r1 we are in a position to take exceptions
* again, and we could thus set MSR:RI at that point.
*/
/*
* Exception vectors.
*/
#define EXCEPTION(n, label, hdlr, xfer) \
. = n; \
label: \
EXCEPTION_PROLOG; \
addi r3,r1,STACK_FRAME_OVERHEAD; \
xfer(n, hdlr)
#define EXC_XFER_TEMPLATE(n, hdlr, trap, copyee, tfer, ret) \
li r10,trap; \
stw r10,_TRAP(r11); \
li r10,MSR_KERNEL; \
copyee(r10, r9); \
bl tfer; \
i##n: \
.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(n, hdlr, n, NOCOPY, transfer_to_handler_full, \
ret_from_except_full)
#define EXC_XFER_LITE(n, hdlr) \
EXC_XFER_TEMPLATE(n, hdlr, n+1, NOCOPY, transfer_to_handler, \
ret_from_except)
#define EXC_XFER_EE(n, hdlr) \
EXC_XFER_TEMPLATE(n, hdlr, n, COPY_EE, transfer_to_handler_full, \
ret_from_except_full)
#define EXC_XFER_EE_LITE(n, hdlr) \
EXC_XFER_TEMPLATE(n, hdlr, n+1, COPY_EE, transfer_to_handler, \
ret_from_except)
/* System reset */
EXCEPTION(0x100, Reset, system_reset_exception, EXC_XFER_STD)
/* Machine check */
. = 0x200
MachineCheck:
EXCEPTION_PROLOG
mfspr r4,SPRN_DAR
stw r4,_DAR(r11)
li r5,RPN_PATTERN
mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
mfspr r5,SPRN_DSISR
stw r5,_DSISR(r11)
addi r3,r1,STACK_FRAME_OVERHEAD
EXC_XFER_STD(0x200, machine_check_exception)
/* Data access exception.
* This is "never generated" by the MPC8xx.
*/
. = 0x300
DataAccess:
/* Instruction access exception.
* This is "never generated" by the MPC8xx.
*/
. = 0x400
InstructionAccess:
/* External interrupt */
EXCEPTION(0x500, HardwareInterrupt, do_IRQ, EXC_XFER_LITE)
/* Alignment exception */
. = 0x600
Alignment:
EXCEPTION_PROLOG
mfspr r4,SPRN_DAR
stw r4,_DAR(r11)
li r5,RPN_PATTERN
mtspr SPRN_DAR,r5 /* Tag DAR, to be used in DTLB Error */
mfspr r5,SPRN_DSISR
stw r5,_DSISR(r11)
addi r3,r1,STACK_FRAME_OVERHEAD
EXC_XFER_EE(0x600, alignment_exception)
/* Program check exception */
EXCEPTION(0x700, ProgramCheck, program_check_exception, EXC_XFER_STD)
/* No FPU on MPC8xx. This exception is not supposed to happen.
*/
EXCEPTION(0x800, FPUnavailable, unknown_exception, EXC_XFER_STD)
/* Decrementer */
EXCEPTION(0x900, Decrementer, timer_interrupt, EXC_XFER_LITE)
EXCEPTION(0xa00, Trap_0a, unknown_exception, EXC_XFER_EE)
EXCEPTION(0xb00, Trap_0b, unknown_exception, EXC_XFER_EE)
/* System call */
. = 0xc00
SystemCall:
EXCEPTION_PROLOG
EXC_XFER_EE_LITE(0xc00, DoSyscall)
/* Single step - not used on 601 */
EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)
EXCEPTION(0xe00, Trap_0e, unknown_exception, EXC_XFER_EE)
EXCEPTION(0xf00, Trap_0f, unknown_exception, EXC_XFER_EE)
/* On the MPC8xx, this is a software emulation interrupt. It occurs
* for all unimplemented and illegal instructions.
*/
EXCEPTION(0x1000, SoftEmu, program_check_exception, EXC_XFER_STD)
. = 0x1100
/*
* For the MPC8xx, this is a software tablewalk to load the instruction
* TLB. The task switch loads the M_TW register with the pointer to the first
* level table.
* If we discover there is no second level table (value is zero) or if there
* is an invalid pte, we load that into the TLB, which causes another fault
* into the TLB Error interrupt where we can handle such problems.
* We have to use the MD_xxx registers for the tablewalk because the
* equivalent MI_xxx registers only perform the attribute functions.
*/
#ifdef CONFIG_8xx_CPU15
#define INVALIDATE_ADJACENT_PAGES_CPU15(tmp, addr) \
addi tmp, addr, PAGE_SIZE; \
tlbie tmp; \
addi tmp, addr, -PAGE_SIZE; \
tlbie tmp
#else
#define INVALIDATE_ADJACENT_PAGES_CPU15(tmp, addr)
#endif
InstructionTLBMiss:
mtspr SPRN_SPRG_SCRATCH0, r10
mtspr SPRN_SPRG_SCRATCH1, r11
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mtspr SPRN_SPRG_SCRATCH2, r12
#endif
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
mfspr r10, SPRN_SRR0 /* Get effective address of fault */
INVALIDATE_ADJACENT_PAGES_CPU15(r11, r10)
/* Only modules will cause ITLB Misses as we always
* pin the first 8MB of kernel memory */
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mfcr r12
#endif
#ifdef ITLB_MISS_KERNEL
#if defined(SIMPLE_KERNEL_ADDRESS) && defined(CONFIG_PIN_TLB_TEXT)
andis. r11, r10, 0x8000 /* Address >= 0x80000000 */
#else
rlwinm r11, r10, 16, 0xfff8
cmpli cr0, r11, PAGE_OFFSET@h
#ifndef CONFIG_PIN_TLB_TEXT
/* It is assumed that kernel code fits into the first 8M page */
_ENTRY(ITLBMiss_cmp)
cmpli cr7, r11, (PAGE_OFFSET + 0x0800000)@h
#endif
#endif
#endif
mfspr r11, SPRN_M_TW /* Get level 1 table */
#ifdef ITLB_MISS_KERNEL
#if defined(SIMPLE_KERNEL_ADDRESS) && defined(CONFIG_PIN_TLB_TEXT)
beq+ 3f
#else
blt+ 3f
#endif
#ifndef CONFIG_PIN_TLB_TEXT
blt cr7, ITLBMissLinear
#endif
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
#endif
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
/* Extract level 2 index */
rlwinm r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
#ifdef CONFIG_HUGETLB_PAGE
mtcr r11
bt- 28, 10f /* bit 28 = Large page (8M) */
bt- 29, 20f /* bit 29 = Large page (8M or 512k) */
#endif
rlwimi r10, r11, 0, 0, 32 - PAGE_SHIFT - 1 /* Add level 2 base */
lwz r10, 0(r10) /* Get the pte */
4:
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mtcr r12
#endif
#ifdef CONFIG_SWAP
rlwinm r11, r10, 31, _PAGE_ACCESSED >> 1
#endif
/* Load the MI_TWC with the attributes for this "segment." */
mtspr SPRN_MI_TWC, r11 /* Set segment attributes */
li r11, RPN_PATTERN | 0x200
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 20 and 23 must be clear.
* Software indicator bits 22, 24, 25, 26, and 27 must be
* set. All other Linux PTE bits control the behavior
* of the MMU.
*/
rlwimi r11, r10, 4, 0x0400 /* Copy _PAGE_EXEC into bit 21 */
rlwimi r10, r11, 0, 0x0ff0 /* Set 22, 24-27, clear 20,23 */
mtspr SPRN_MI_RPN, r10 /* Update TLB entry */
/* Restore registers */
_ENTRY(itlb_miss_exit_1)
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mfspr r12, SPRN_SPRG_SCRATCH2
#endif
rfi
#ifdef CONFIG_PERF_EVENTS
_ENTRY(itlb_miss_perf)
lis r10, (itlb_miss_counter - PAGE_OFFSET)@ha
lwz r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)
addi r11, r11, 1
stw r11, (itlb_miss_counter - PAGE_OFFSET)@l(r10)
#endif
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
#if defined(ITLB_MISS_KERNEL) || defined(CONFIG_HUGETLB_PAGE)
mfspr r12, SPRN_SPRG_SCRATCH2
#endif
rfi
#ifdef CONFIG_HUGETLB_PAGE
10: /* 8M pages */
#ifdef CONFIG_PPC_16K_PAGES
/* Extract level 2 index */
rlwinm r10, r10, 32 - (PAGE_SHIFT_8M - PAGE_SHIFT), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
/* Add level 2 base */
rlwimi r10, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
#else
/* Level 2 base */
rlwinm r10, r11, 0, ~HUGEPD_SHIFT_MASK
#endif
lwz r10, 0(r10) /* Get the pte */
b 4b
20: /* 512k pages */
/* Extract level 2 index */
rlwinm r10, r10, 32 - (PAGE_SHIFT_512K - PAGE_SHIFT), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
/* Add level 2 base */
rlwimi r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
lwz r10, 0(r10) /* Get the pte */
b 4b
#endif
. = 0x1200
DataStoreTLBMiss:
mtspr SPRN_SPRG_SCRATCH0, r10
mtspr SPRN_SPRG_SCRATCH1, r11
mtspr SPRN_SPRG_SCRATCH2, r12
mfcr r12
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
mfspr r10, SPRN_MD_EPN
rlwinm r11, r10, 16, 0xfff8
cmpli cr0, r11, PAGE_OFFSET@h
mfspr r11, SPRN_M_TW /* Get level 1 table */
blt+ 3f
rlwinm r11, r10, 16, 0xfff8
#ifndef CONFIG_PIN_TLB_IMMR
cmpli cr0, r11, VIRT_IMMR_BASE@h
#endif
_ENTRY(DTLBMiss_cmp)
cmpli cr7, r11, (PAGE_OFFSET + 0x1800000)@h
#ifndef CONFIG_PIN_TLB_IMMR
_ENTRY(DTLBMiss_jmp)
beq- DTLBMissIMMR
#endif
blt cr7, DTLBMissLinear
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
3:
/* Insert level 1 index */
rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
/* We have a pte table, so load fetch the pte from the table.
*/
/* Extract level 2 index */
rlwinm r10, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
#ifdef CONFIG_HUGETLB_PAGE
mtcr r11
bt- 28, 10f /* bit 28 = Large page (8M) */
bt- 29, 20f /* bit 29 = Large page (8M or 512k) */
#endif
rlwimi r10, r11, 0, 0, 32 - PAGE_SHIFT - 1 /* Add level 2 base */
lwz r10, 0(r10) /* Get the pte */
4:
mtcr r12
/* 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 r11, r10, 0, _PAGE_GUARDED
#ifdef CONFIG_SWAP
/* _PAGE_ACCESSED has to be set. We use second APG bit for that, 0
* on that bit will represent a Non Access group
*/
rlwinm r11, r10, 31, _PAGE_ACCESSED >> 1
#endif
mtspr SPRN_MD_TWC, r11
/* The Linux PTE won't go exactly into the MMU TLB.
* Software indicator bits 24, 25, 26, and 27 must be
* set. All other Linux PTE bits control the behavior
* of the MMU.
*/
li r11, RPN_PATTERN
rlwimi r10, r11, 0, 24, 27 /* Set 24-27 */
mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
/* Restore registers */
mtspr SPRN_DAR, r11 /* Tag DAR */
_ENTRY(dtlb_miss_exit_1)
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r12, SPRN_SPRG_SCRATCH2
rfi
#ifdef CONFIG_PERF_EVENTS
_ENTRY(dtlb_miss_perf)
lis r10, (dtlb_miss_counter - PAGE_OFFSET)@ha
lwz r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)
addi r11, r11, 1
stw r11, (dtlb_miss_counter - PAGE_OFFSET)@l(r10)
#endif
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r12, SPRN_SPRG_SCRATCH2
rfi
#ifdef CONFIG_HUGETLB_PAGE
10: /* 8M pages */
/* Extract level 2 index */
#ifdef CONFIG_PPC_16K_PAGES
rlwinm r10, r10, 32 - (PAGE_SHIFT_8M - PAGE_SHIFT), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
/* Add level 2 base */
rlwimi r10, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
#else
/* Level 2 base */
rlwinm r10, r11, 0, ~HUGEPD_SHIFT_MASK
#endif
lwz r10, 0(r10) /* Get the pte */
b 4b
20: /* 512k pages */
/* Extract level 2 index */
rlwinm r10, r10, 32 - (PAGE_SHIFT_512K - PAGE_SHIFT), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
/* Add level 2 base */
rlwimi r10, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
lwz r10, 0(r10) /* Get the pte */
b 4b
#endif
/* 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:
EXCEPTION_PROLOG
mr r4,r12
andis. r5,r9,DSISR_SRR1_MATCH_32S@h /* Filter relevant SRR1 bits */
andis. r10,r9,SRR1_ISI_NOPT@h
beq+ 1f
tlbie r4
itlbie:
/* 0x400 is InstructionAccess exception, needed by bad_page_fault() */
1: EXC_XFER_LITE(0x400, handle_page_fault)
/* This is the data TLB error on the MPC8xx. This could be due to
* many reasons, including a dirty update to a pte. We bail out to
* a higher level function that can handle it.
*/
. = 0x1400
DataTLBError:
mtspr SPRN_SPRG_SCRATCH0, r10
mtspr SPRN_SPRG_SCRATCH1, r11
mfcr r10
mfspr r11, SPRN_DAR
cmpwi cr0, r11, RPN_PATTERN
beq- FixupDAR /* must be a buggy dcbX, icbi insn. */
DARFixed:/* Return from dcbx instruction bug workaround */
EXCEPTION_PROLOG_1
EXCEPTION_PROLOG_2
mfspr r5,SPRN_DSISR
stw r5,_DSISR(r11)
mfspr r4,SPRN_DAR
andis. r10,r5,DSISR_NOHPTE@h
beq+ 1f
tlbie r4
dtlbie:
1: li r10,RPN_PATTERN
mtspr SPRN_DAR,r10 /* Tag DAR, to be used in DTLB Error */
/* 0x300 is DataAccess exception, needed by bad_page_fault() */
EXC_XFER_LITE(0x300, handle_page_fault)
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.
*/
. = 0x1c00
DataBreakpoint:
mtspr SPRN_SPRG_SCRATCH0, r10
mtspr SPRN_SPRG_SCRATCH1, r11
mfcr r10
mfspr r11, SPRN_SRR0
cmplwi cr0, r11, (dtlbie - PAGE_OFFSET)@l
cmplwi cr7, r11, (itlbie - PAGE_OFFSET)@l
beq- cr0, 11f
beq- cr7, 11f
EXCEPTION_PROLOG_1
EXCEPTION_PROLOG_2
addi r3,r1,STACK_FRAME_OVERHEAD
mfspr r4,SPRN_BAR
stw r4,_DAR(r11)
mfspr r5,SPRN_DSISR
EXC_XFER_EE(0x1c00, do_break)
11:
mtcr r10
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
rfi
#ifdef CONFIG_PERF_EVENTS
. = 0x1d00
InstructionBreakpoint:
mtspr SPRN_SPRG_SCRATCH0, r10
mtspr SPRN_SPRG_SCRATCH1, r11
lis r10, (instruction_counter - PAGE_OFFSET)@ha
lwz r11, (instruction_counter - PAGE_OFFSET)@l(r10)
addi r11, r11, -1
stw r11, (instruction_counter - PAGE_OFFSET)@l(r10)
lis r10, 0xffff
ori r10, r10, 0x01
mtspr SPRN_COUNTA, r10
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
rfi
#else
EXCEPTION(0x1d00, Trap_1d, unknown_exception, EXC_XFER_EE)
#endif
EXCEPTION(0x1e00, Trap_1e, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x1f00, Trap_1f, unknown_exception, EXC_XFER_EE)
. = 0x2000
/*
* Bottom part of DataStoreTLBMiss handlers for IMMR area and linear RAM.
* not enough space in the DataStoreTLBMiss area.
*/
DTLBMissIMMR:
mtcr r12
/* Set 512k byte guarded page and mark it valid and accessed */
li r10, MD_PS512K | MD_GUARDED | MD_SVALID | M_APG2
mtspr SPRN_MD_TWC, r10
mfspr r10, SPRN_IMMR /* Get current IMMR */
rlwinm r10, r10, 0, 0xfff80000 /* Get 512 kbytes boundary */
ori r10, r10, 0xf0 | MD_SPS16K | _PAGE_PRIVILEGED | _PAGE_DIRTY | \
_PAGE_PRESENT | _PAGE_NO_CACHE
mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
li r11, RPN_PATTERN
mtspr SPRN_DAR, r11 /* Tag DAR */
_ENTRY(dtlb_miss_exit_2)
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r12, SPRN_SPRG_SCRATCH2
rfi
DTLBMissLinear:
mtcr r12
/* Set 8M byte page and mark it valid and accessed */
li r11, MD_PS8MEG | MD_SVALID | M_APG2
mtspr SPRN_MD_TWC, r11
rlwinm r10, r10, 0, 0x0f800000 /* 8xx supports max 256Mb RAM */
ori r10, r10, 0xf0 | MD_SPS16K | _PAGE_PRIVILEGED | _PAGE_DIRTY | \
_PAGE_PRESENT
mtspr SPRN_MD_RPN, r10 /* Update TLB entry */
li r11, RPN_PATTERN
mtspr SPRN_DAR, r11 /* Tag DAR */
_ENTRY(dtlb_miss_exit_3)
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r12, SPRN_SPRG_SCRATCH2
rfi
#ifndef CONFIG_PIN_TLB_TEXT
ITLBMissLinear:
mtcr r12
/* Set 8M byte page and mark it valid,accessed */
li r11, MI_PS8MEG | MI_SVALID | M_APG2
mtspr SPRN_MI_TWC, r11
rlwinm r10, r10, 0, 0x0f800000 /* 8xx supports max 256Mb RAM */
ori r10, r10, 0xf0 | MI_SPS16K | _PAGE_PRIVILEGED | _PAGE_DIRTY | \
_PAGE_PRESENT
mtspr SPRN_MI_RPN, r10 /* Update TLB entry */
_ENTRY(itlb_miss_exit_2)
mfspr r10, SPRN_SPRG_SCRATCH0
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r12, SPRN_SPRG_SCRATCH2
rfi
#endif
/* This is the procedure to calculate the data EA for buggy dcbx,dcbi instructions
* by decoding the registers used by the dcbx instruction and adding them.
* DAR is set to the calculated address.
*/
/* define if you don't want to use self modifying code */
#define NO_SELF_MODIFYING_CODE
FixupDAR:/* Entry point for dcbx workaround. */
mtspr SPRN_SPRG_SCRATCH2, r10
/* fetch instruction from memory. */
mfspr r10, SPRN_SRR0
rlwinm r11, r10, 16, 0xfff8
cmpli cr0, r11, PAGE_OFFSET@h
mfspr r11, SPRN_M_TW /* Get level 1 table */
blt+ 3f
rlwinm r11, r10, 16, 0xfff8
_ENTRY(FixupDAR_cmp)
cmpli cr7, r11, (PAGE_OFFSET + 0x1800000)@h
/* create physical page address from effective address */
tophys(r11, r10)
blt- cr7, 201f
lis r11, (swapper_pg_dir-PAGE_OFFSET)@ha
/* Insert level 1 index */
3: rlwimi r11, r10, 32 - ((PAGE_SHIFT - 2) << 1), (PAGE_SHIFT - 2) << 1, 29
lwz r11, (swapper_pg_dir-PAGE_OFFSET)@l(r11) /* Get the level 1 entry */
mtcr r11
bt 28,200f /* bit 28 = Large page (8M) */
bt 29,202f /* bit 29 = Large page (8M or 512K) */
rlwinm r11, r11,0,0,19 /* Extract page descriptor page address */
/* Insert level 2 index */
rlwimi r11, r10, 32 - (PAGE_SHIFT - 2), 32 - PAGE_SHIFT, 29
lwz r11, 0(r11) /* Get the pte */
/* concat physical page address(r11) and page offset(r10) */
rlwimi r11, r10, 0, 32 - PAGE_SHIFT, 31
201: lwz r11,0(r11)
/* Check if it really is a dcbx instruction. */
/* dcbt and dcbtst does not generate DTLB Misses/Errors,
* no need to include them here */
xoris r10, r11, 0x7c00 /* check if major OP code is 31 */
rlwinm r10, r10, 0, 21, 5
cmpwi cr0, r10, 2028 /* Is dcbz? */
beq+ 142f
cmpwi cr0, r10, 940 /* Is dcbi? */
beq+ 142f
cmpwi cr0, r10, 108 /* Is dcbst? */
beq+ 144f /* Fix up store bit! */
cmpwi cr0, r10, 172 /* Is dcbf? */
beq+ 142f
cmpwi cr0, r10, 1964 /* Is icbi? */
beq+ 142f
141: mfspr r10,SPRN_SPRG_SCRATCH2
b DARFixed /* Nope, go back to normal TLB processing */
/* concat physical page address(r11) and page offset(r10) */
200:
#ifdef CONFIG_PPC_16K_PAGES
rlwinm r11, r11, 0, 0, 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1) - 1
rlwimi r11, r10, 32 - (PAGE_SHIFT_8M - 2), 32 + PAGE_SHIFT_8M - (PAGE_SHIFT << 1), 29
#else
rlwinm r11, r10, 0, ~HUGEPD_SHIFT_MASK
#endif
lwz r11, 0(r11) /* Get the pte */
/* concat physical page address(r11) and page offset(r10) */
rlwimi r11, r10, 0, 32 - PAGE_SHIFT_8M, 31
b 201b
202:
rlwinm r11, r11, 0, 0, 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1) - 1
rlwimi r11, r10, 32 - (PAGE_SHIFT_512K - 2), 32 + PAGE_SHIFT_512K - (PAGE_SHIFT << 1), 29
lwz r11, 0(r11) /* Get the pte */
/* concat physical page address(r11) and page offset(r10) */
rlwimi r11, r10, 0, 32 - PAGE_SHIFT_512K, 31
b 201b
144: mfspr r10, SPRN_DSISR
rlwinm r10, r10,0,7,5 /* Clear store bit for buggy dcbst insn */
mtspr SPRN_DSISR, r10
142: /* continue, it was a dcbx, dcbi instruction. */
#ifndef NO_SELF_MODIFYING_CODE
andis. r10,r11,0x1f /* test if reg RA is r0 */
li r10,modified_instr@l
dcbtst r0,r10 /* touch for store */
rlwinm r11,r11,0,0,20 /* Zero lower 10 bits */
oris r11,r11,640 /* Transform instr. to a "add r10,RA,RB" */
ori r11,r11,532
stw r11,0(r10) /* store add/and instruction */
dcbf 0,r10 /* flush new instr. to memory. */
icbi 0,r10 /* invalidate instr. cache line */
mfspr r11, SPRN_SPRG_SCRATCH1 /* restore r11 */
mfspr r10, SPRN_SPRG_SCRATCH0 /* restore r10 */
isync /* Wait until new instr is loaded from memory */
modified_instr:
.space 4 /* this is where the add instr. is stored */
bne+ 143f
subf r10,r0,r10 /* r10=r10-r0, only if reg RA is r0 */
143: mtdar r10 /* store faulting EA in DAR */
mfspr r10,SPRN_SPRG_SCRATCH2
b DARFixed /* Go back to normal TLB handling */
#else
mfctr r10
mtdar r10 /* save ctr reg in DAR */
rlwinm r10, r11, 24, 24, 28 /* offset into jump table for reg RB */
addi r10, r10, 150f@l /* add start of table */
mtctr r10 /* load ctr with jump address */
xor r10, r10, r10 /* sum starts at zero */
bctr /* jump into table */
150:
add r10, r10, r0 ;b 151f
add r10, r10, r1 ;b 151f
add r10, r10, r2 ;b 151f
add r10, r10, r3 ;b 151f
add r10, r10, r4 ;b 151f
add r10, r10, r5 ;b 151f
add r10, r10, r6 ;b 151f
add r10, r10, r7 ;b 151f
add r10, r10, r8 ;b 151f
add r10, r10, r9 ;b 151f
mtctr r11 ;b 154f /* r10 needs special handling */
mtctr r11 ;b 153f /* r11 needs special handling */
add r10, r10, r12 ;b 151f
add r10, r10, r13 ;b 151f
add r10, r10, r14 ;b 151f
add r10, r10, r15 ;b 151f
add r10, r10, r16 ;b 151f
add r10, r10, r17 ;b 151f
add r10, r10, r18 ;b 151f
add r10, r10, r19 ;b 151f
add r10, r10, r20 ;b 151f
add r10, r10, r21 ;b 151f
add r10, r10, r22 ;b 151f
add r10, r10, r23 ;b 151f
add r10, r10, r24 ;b 151f
add r10, r10, r25 ;b 151f
add r10, r10, r26 ;b 151f
add r10, r10, r27 ;b 151f
add r10, r10, r28 ;b 151f
add r10, r10, r29 ;b 151f
add r10, r10, r30 ;b 151f
add r10, r10, r31
151:
rlwinm. r11,r11,19,24,28 /* offset into jump table for reg RA */
beq 152f /* if reg RA is zero, don't add it */
addi r11, r11, 150b@l /* add start of table */
mtctr r11 /* load ctr with jump address */
rlwinm r11,r11,0,16,10 /* make sure we don't execute this more than once */
bctr /* jump into table */
152:
mfdar r11
mtctr r11 /* restore ctr reg from DAR */
mtdar r10 /* save fault EA to DAR */
mfspr r10,SPRN_SPRG_SCRATCH2
b DARFixed /* Go back to normal TLB handling */
/* special handling for r10,r11 since these are modified already */
153: mfspr r11, SPRN_SPRG_SCRATCH1 /* load r11 from SPRN_SPRG_SCRATCH1 */
add r10, r10, r11 /* add it */
mfctr r11 /* restore r11 */
b 151b
154: mfspr r11, SPRN_SPRG_SCRATCH0 /* load r10 from SPRN_SPRG_SCRATCH0 */
add r10, r10, r11 /* add it */
mfctr r11 /* restore r11 */
b 151b
#endif
/*
* This is where the main kernel code starts.
*/
start_here:
/* ptr to current */
lis r2,init_task@h
ori r2,r2,init_task@l
/* ptr to phys current thread */
tophys(r4,r2)
addi r4,r4,THREAD /* init task's THREAD */
mtspr SPRN_SPRG_THREAD,r4
/* stack */
lis r1,init_thread_union@ha
addi r1,r1,init_thread_union@l
li r0,0
stwu r0,THREAD_SIZE-STACK_FRAME_OVERHEAD(r1)
bl early_init /* We have to do this with MMU on */
/*
* Decide what sort of machine this is and initialize the MMU.
*/
li r3,0
mr r4,r31
bl machine_init
bl MMU_init
/*
* Go back to running unmapped so we can load up new values
* and change to using our exception vectors.
* On the 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@ha
tophys(r6,r6)
mtspr SPRN_M_TW, 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:
tlbia /* Clear all TLB entries */
sync /* wait for tlbia/tlbie to finish */
/* 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 512k IMMR space. Anything not covered by
* these mappings is mapped by page tables.
*/
initial_mmu:
li r8, 0
mtspr SPRN_MI_CTR, r8 /* remove PINNED ITLB entries */
lis r10, MD_RESETVAL@h
#ifndef CONFIG_8xx_COPYBACK
oris r10, r10, MD_WTDEF@h
#endif
mtspr SPRN_MD_CTR, r10 /* remove PINNED DTLB entries */
tlbia /* Invalidate all TLB entries */
#ifdef CONFIG_PIN_TLB_TEXT
lis r8, MI_RSV4I@h
ori r8, r8, 0x1c00
mtspr SPRN_MI_CTR, r8 /* Set instruction MMU control */
#endif
#ifdef CONFIG_PIN_TLB_DATA
oris r10, r10, MD_RSV4I@h
mtspr SPRN_MD_CTR, r10 /* Set data TLB control */
#endif
/* Now map the lower 8 Meg into the ITLB. */
lis r8, KERNELBASE@h /* Create vaddr for TLB */
ori r8, r8, MI_EVALID /* Mark it valid */
mtspr SPRN_MI_EPN, r8
li r8, MI_PS8MEG /* Set 8M byte page */
ori r8, r8, MI_SVALID | M_APG2 /* Make it valid, APG 2 */
mtspr SPRN_MI_TWC, r8
li r8, MI_BOOTINIT /* Create RPN for address 0 */
mtspr SPRN_MI_RPN, r8 /* Store TLB entry */
lis r8, MI_APG_INIT@h /* Set protection modes */
ori r8, r8, MI_APG_INIT@l
mtspr SPRN_MI_AP, r8
lis r8, MD_APG_INIT@h
ori r8, r8, MD_APG_INIT@l
mtspr SPRN_MD_AP, r8
/* Map a 512k page for the IMMR to get the processor
* internal registers (among other things).
*/
#ifdef CONFIG_PIN_TLB_IMMR
oris r10, r10, MD_RSV4I@h
ori r10, r10, 0x1c00
mtspr SPRN_MD_CTR, r10
mfspr r9, 638 /* Get current IMMR */
andis. r9, r9, 0xfff8 /* Get 512 kbytes boundary */
lis r8, VIRT_IMMR_BASE@h /* Create vaddr for TLB */
ori r8, r8, MD_EVALID /* Mark it valid */
mtspr SPRN_MD_EPN, r8
li r8, MD_PS512K | MD_GUARDED /* Set 512k byte page */
ori r8, r8, MD_SVALID | M_APG2 /* Make it valid and accessed */
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
#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
/* Disable debug mode entry on breakpoints */
mfspr r8, SPRN_DER
#ifdef CONFIG_PERF_EVENTS
rlwinm r8, r8, 0, ~0xc
#else
rlwinm r8, r8, 0, ~0x8
#endif
mtspr SPRN_DER, r8
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
.globl sdata
sdata:
.globl empty_zero_page
.align PAGE_SHIFT
empty_zero_page:
.space PAGE_SIZE
EXPORT_SYMBOL(empty_zero_page)
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
/* 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_PERF_EVENTS
.globl itlb_miss_counter
itlb_miss_counter:
.space 4
.globl dtlb_miss_counter
dtlb_miss_counter:
.space 4
.globl instruction_counter
instruction_counter:
.space 4
#endif
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