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linux/arch/powerpc/kernel/head_40x.S
Benjamin Herrenschmidt a546498f3b powerpc: Call do_page_fault() with interrupts off 
We currently turn interrupts back to their previous state before
calling do_page_fault(). This can be annoying when debugging as
a bad fault will potentially have lost some processor state before
getting into the debugger.

We also end up calling some generic code with interrupts enabled
such as notify_page_fault() with interrupts enabled, which could
be unexpected.

This changes our code to behave more like other architectures,
and make the assembly entry code call into do_page_faults() with
interrupts disabled. They are conditionally re-enabled from
within do_page_fault() in the same spot x86 does it.

While there, add the might_sleep() test in the case of a successful
trylock of the mmap semaphore, again like x86.

Also fix a bug in the existing assembly where r12 (_MSR) could get
clobbered by C calls (the DTL accounting in the exception common
macro and DISABLE_INTS) in some cases.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

v2. Add the r12 clobber fix
2012-03-09 10:55:08 +11:00

999 lines
28 KiB
ArmAsm
Raw Blame History

/*
* 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>
#include <asm/ptrace.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);
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 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_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_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 - available 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.
*/
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 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 one entry into TLB slots 63 */
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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