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alistair23-linux/arch/powerpc/kernel/head_40x.S
Benjamin Herrenschmidt ee43eb788b powerpc: Use names rather than numbers for SPRGs (v2) 
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>
2009-08-20 10:12:27 +10:00

1011 lines
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/*
* 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/init.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/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
*/
__HEAD
_ENTRY(_stext);
_ENTRY(_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:
_ENTRY(crit_r10)
.space 4
_ENTRY(crit_r11)
.space 4
_ENTRY(crit_srr0)
.space 4
_ENTRY(crit_srr1)
.space 4
_ENTRY(saved_ksp_limit)
.space 4
/*
* Exception vector entry code. This code runs with address translation
* turned off (i.e. using physical addresses). We assume SPRG_THREAD 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_SPRG_SCRATCH0,r10; /* save two registers to work with */\
mtspr SPRN_SPRG_SCRATCH1,r11; \
mtspr SPRN_SPRG_SCRATCH2,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_SPRG_THREAD; /* 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_SPRG_SCRATCH0; \
stw r10,GPR10(r11); \
mfspr r12,SPRN_SPRG_SCRATCH1; \
stw r12,GPR11(r11); \
mflr r10; \
stw r10,_LINK(r11); \
mfspr r10,SPRN_SPRG_SCRATCH2; \
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,critirq_ctx@ha; \
tophys(r11,r11); \
lwz r11,critirq_ctx@l(r11); \
beq 1f; \
/* COMING FROM USER MODE */ \
mfspr r11,SPRN_SPRG_THREAD; /* if from user, start at top of */\
lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
1: addi r11,r11,THREAD_SIZE-INT_FRAME_SIZE; /* Alloc an excpt frm */\
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, unknown_exception)
/*
* 0x0200 - Machine Check Exception
*/
CRITICAL_EXCEPTION(0x0200, MachineCheck, machine_check_exception)
/*
* 0x0300 - Data Storage Exception
* This happens for just a few reasons. U0 set (but we don't do that),
* or zone protection fault (user violation, write to protected page).
* 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_SPRG_SCRATCH0, r10 /* Save some working registers */
mtspr SPRN_SPRG_SCRATCH1, 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_SPRG_SCRATCH3, r12
mtspr SPRN_SPRG_SCRATCH4, r9
mfcr r11
mfspr r12, SPRN_PID
mtspr SPRN_SPRG_SCRATCH6, r11
mtspr SPRN_SPRG_SCRATCH5, 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.
*/
lis r11, PAGE_OFFSET@h
cmplw r10, r11
blt+ 3f
lis r11, swapper_pg_dir@h
ori r11, r11, swapper_pg_dir@l
li r9, 0
mtspr SPRN_PID, r9 /* TLB will have 0 TID */
b 4f
/* Get the PGD for the current thread.
*/
3:
mfspr r11,SPRN_SPRG_THREAD
lwz r11,PGDIR(r11)
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_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12
mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3
#endif
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r10, SPRN_SPRG_SCRATCH0
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_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12
mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3
#endif
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r10, SPRN_SPRG_SCRATCH0
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, alignment_exception)
/* 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, program_check_exception)
EXCEPTION(0x0800, Trap_08, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x0900, Trap_09, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x0A00, Trap_0A, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x0B00, Trap_0B, unknown_exception, EXC_XFER_EE)
/* 0x0C00 - System Call Exception */
START_EXCEPTION(0x0C00, SystemCall)
NORMAL_EXCEPTION_PROLOG
EXC_XFER_EE_LITE(0xc00, DoSyscall)
EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x0F00, Trap_0F, unknown_exception, 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, unknown_exception)
/* 0x1020 - Watchdog Timer (WDT) Exception
*/
#ifdef CONFIG_BOOKE_WDT
CRITICAL_EXCEPTION(0x1020, WDTException, WatchdogException)
#else
CRITICAL_EXCEPTION(0x1020, WDTException, unknown_exception)
#endif
#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_SPRG_SCRATCH0, r10 /* Save some working registers */
mtspr SPRN_SPRG_SCRATCH1, 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_SPRG_SCRATCH3, r12
mtspr SPRN_SPRG_SCRATCH4, r9
mfcr r11
mfspr r12, SPRN_PID
mtspr SPRN_SPRG_SCRATCH6, r11
mtspr SPRN_SPRG_SCRATCH5, r12
#endif
mfspr r10, SPRN_DEAR /* Get faulting address */
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
lis r11, PAGE_OFFSET@h
cmplw r10, r11
blt+ 3f
lis r11, swapper_pg_dir@h
ori r11, r11, swapper_pg_dir@l
li r9, 0
mtspr SPRN_PID, r9 /* TLB will have 0 TID */
b 4f
/* Get the PGD for the current thread.
*/
3:
mfspr r11,SPRN_SPRG_THREAD
lwz r11,PGDIR(r11)
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_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12
mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3
#endif
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r10, SPRN_SPRG_SCRATCH0
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_SPRG_SCRATCH0, r10 /* Save some working registers */
mtspr SPRN_SPRG_SCRATCH1, 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_SPRG_SCRATCH3, r12
mtspr SPRN_SPRG_SCRATCH4, r9
mfcr r11
mfspr r12, SPRN_PID
mtspr SPRN_SPRG_SCRATCH6, r11
mtspr SPRN_SPRG_SCRATCH5, r12
#endif
mfspr r10, SPRN_SRR0 /* Get faulting address */
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
lis r11, PAGE_OFFSET@h
cmplw r10, r11
blt+ 3f
lis r11, swapper_pg_dir@h
ori r11, r11, swapper_pg_dir@l
li r9, 0
mtspr SPRN_PID, r9 /* TLB will have 0 TID */
b 4f
/* Get the PGD for the current thread.
*/
3:
mfspr r11,SPRN_SPRG_THREAD
lwz r11,PGDIR(r11)
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_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12
mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3
#endif
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r10, SPRN_SPRG_SCRATCH0
b InstructionAccess
EXCEPTION(0x1300, Trap_13, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x1400, Trap_14, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x1500, Trap_15, unknown_exception, EXC_XFER_EE)
EXCEPTION(0x1600, Trap_16, unknown_exception, EXC_XFER_EE)
#ifdef CONFIG_IBM405_ERR51
/* 405GP errata 51 */
START_EXCEPTION(0x1700, Trap_17)
b DTLBMiss
#else
EXCEPTION(0x1700, Trap_17, unknown_exception, EXC_XFER_EE)
#endif
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)
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)
/* 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, (PPC40X_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_SPRG_SCRATCH5
mfspr r11, SPRN_SPRG_SCRATCH6
mtspr SPRN_PID, r12
mtcr r11
mfspr r9, SPRN_SPRG_SCRATCH4
mfspr r12, SPRN_SPRG_SCRATCH3
#endif
mfspr r11, SPRN_SPRG_SCRATCH1
mfspr r10, SPRN_SPRG_SCRATCH0
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.
*/
_ENTRY(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
/* 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
.align 12
.globl sdata
sdata:
.globl empty_zero_page
empty_zero_page:
.space 4096
.globl swapper_pg_dir
swapper_pg_dir:
.space PGD_TABLE_SIZE
/* Room for two PTE pointers, usually the kernel and current user pointers
* to their respective root page table.
*/
abatron_pteptrs:
.space 8
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