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linux/arch/microblaze/kernel/hw_exception_handler.S
Michal Simek e02db0aa3e microblaze: Handle TLB skip size dynamically 
This patch fix the problem with rootfs on JFFS2 with early printk
console turned on.

The origin version used TLB63 for temporary early printk mapping.
The code expect that kernel is not able to use all 64 TLB entries
till early printk console is remapped by ioremap. After that
temporary mapping on TLB63 is silently lost.
This expectation give the opportunity to have early console pretty
early.

Microblaze systems with JFFS2 rootfs with early printk console turned on
used more than 64 TLB entries before kernel can remap early console.
Based on that kernel does access to bad area because early printk mapping
is rewritten.

This patch introduces tlb_skip variable which dynamically stores number
of skipped TLB entries from the TLB0. skip_tlb=2 means that TLB0 and TLB1
should be skipped.

MICROBLAZE_TLB_SKIP defines how many TLB is skipped at the kernel start.
They can be used for user purpose.

TLB 63 is used for temporary LMB mapping (MICROBLAZE_LMB_TLB_ID).

Also clean TLBLO when kernel starts.

For specific kernel sizes kernel can use just one TLB. Detect this case
and use the second TLB for general purpose.

Change _tlbia function to flush TLB entries from tlb_skip to TLB_SIZE.

Export tlb_skip size through debugfs.

Signed-off-by: Michal Simek <monstr@monstr.eu>
2012-03-23 09:28:19 +01:00

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/*
* Exception handling for Microblaze
*
* Rewriten interrupt handling
*
* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2008-2009 PetaLogix
*
* uClinux customisation (C) 2005 John Williams
*
* MMU code derived from arch/ppc/kernel/head_4xx.S:
* 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
*
* Original code
* Copyright (C) 2004 Xilinx, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*/
/*
* Here are the handlers which don't require enabling translation
* and calling other kernel code thus we can keep their design very simple
* and do all processing in real mode. All what they need is a valid current
* (that is an issue for the CONFIG_REGISTER_TASK_PTR case)
* This handlers use r3,r4,r5,r6 and optionally r[current] to work therefore
* these registers are saved/restored
* The handlers which require translation are in entry.S --KAA
*
* Microblaze HW Exception Handler
* - Non self-modifying exception handler for the following exception conditions
* - Unalignment
* - Instruction bus error
* - Data bus error
* - Illegal instruction opcode
* - Divide-by-zero
*
* - Privileged instruction exception (MMU)
* - Data storage exception (MMU)
* - Instruction storage exception (MMU)
* - Data TLB miss exception (MMU)
* - Instruction TLB miss exception (MMU)
*
* Note we disable interrupts during exception handling, otherwise we will
* possibly get multiple re-entrancy if interrupt handles themselves cause
* exceptions. JW
*/
#include <asm/exceptions.h>
#include <asm/unistd.h>
#include <asm/page.h>
#include <asm/entry.h>
#include <asm/current.h>
#include <linux/linkage.h>
#include <asm/mmu.h>
#include <asm/pgtable.h>
#include <asm/signal.h>
#include <asm/asm-offsets.h>
#undef DEBUG
/* Helpful Macros */
#define NUM_TO_REG(num) r ## num
#ifdef CONFIG_MMU
#define RESTORE_STATE \
lwi r5, r1, 0; \
mts rmsr, r5; \
nop; \
lwi r3, r1, PT_R3; \
lwi r4, r1, PT_R4; \
lwi r5, r1, PT_R5; \
lwi r6, r1, PT_R6; \
lwi r11, r1, PT_R11; \
lwi r31, r1, PT_R31; \
lwi r1, r1, PT_R1;
#endif /* CONFIG_MMU */
#define LWREG_NOP \
bri ex_handler_unhandled; \
nop;
#define SWREG_NOP \
bri ex_handler_unhandled; \
nop;
/* FIXME this is weird - for noMMU kernel is not possible to use brid
* instruction which can shorten executed time
*/
/* r3 is the source */
#define R3_TO_LWREG_V(regnum) \
swi r3, r1, 4 * regnum; \
bri ex_handler_done;
/* r3 is the source */
#define R3_TO_LWREG(regnum) \
or NUM_TO_REG (regnum), r0, r3; \
bri ex_handler_done;
/* r3 is the target */
#define SWREG_TO_R3_V(regnum) \
lwi r3, r1, 4 * regnum; \
bri ex_sw_tail;
/* r3 is the target */
#define SWREG_TO_R3(regnum) \
or r3, r0, NUM_TO_REG (regnum); \
bri ex_sw_tail;
#ifdef CONFIG_MMU
#define R3_TO_LWREG_VM_V(regnum) \
brid ex_lw_end_vm; \
swi r3, r7, 4 * regnum;
#define R3_TO_LWREG_VM(regnum) \
brid ex_lw_end_vm; \
or NUM_TO_REG (regnum), r0, r3;
#define SWREG_TO_R3_VM_V(regnum) \
brid ex_sw_tail_vm; \
lwi r3, r7, 4 * regnum;
#define SWREG_TO_R3_VM(regnum) \
brid ex_sw_tail_vm; \
or r3, r0, NUM_TO_REG (regnum);
/* Shift right instruction depending on available configuration */
#if CONFIG_XILINX_MICROBLAZE0_USE_BARREL > 0
#define BSRLI(rD, rA, imm) \
bsrli rD, rA, imm
#else
#define BSRLI(rD, rA, imm) BSRLI ## imm (rD, rA)
/* Only the used shift constants defined here - add more if needed */
#define BSRLI2(rD, rA) \
srl rD, rA; /* << 1 */ \
srl rD, rD; /* << 2 */
#define BSRLI10(rD, rA) \
srl rD, rA; /* << 1 */ \
srl rD, rD; /* << 2 */ \
srl rD, rD; /* << 3 */ \
srl rD, rD; /* << 4 */ \
srl rD, rD; /* << 5 */ \
srl rD, rD; /* << 6 */ \
srl rD, rD; /* << 7 */ \
srl rD, rD; /* << 8 */ \
srl rD, rD; /* << 9 */ \
srl rD, rD /* << 10 */
#define BSRLI20(rD, rA) \
BSRLI10(rD, rA); \
BSRLI10(rD, rD)
#endif
#endif /* CONFIG_MMU */
.extern other_exception_handler /* Defined in exception.c */
/*
* hw_exception_handler - Handler for exceptions
*
* Exception handler notes:
* - Handles all exceptions
* - Does not handle unaligned exceptions during load into r17, r1, r0.
* - Does not handle unaligned exceptions during store from r17 (cannot be
* done) and r1 (slows down common case)
*
* Relevant register structures
*
* EAR - |----|----|----|----|----|----|----|----|
* - < ## 32 bit faulting address ## >
*
* ESR - |----|----|----|----|----| - | - |-----|-----|
* - W S REG EXC
*
*
* STACK FRAME STRUCTURE (for NO_MMU)
* ---------------------------------
*
* +-------------+ + 0
* | MSR |
* +-------------+ + 4
* | r1 |
* | . |
* | . |
* | . |
* | . |
* | r18 |
* +-------------+ + 76
* | . |
* | . |
*
* MMU kernel uses the same 'pt_pool_space' pointed space
* which is used for storing register values - noMMu style was, that values were
* stored in stack but in case of failure you lost information about register.
* Currently you can see register value in memory in specific place.
* In compare to with previous solution the speed should be the same.
*
* MMU exception handler has different handling compare to no MMU kernel.
* Exception handler use jump table for directing of what happen. For MMU kernel
* is this approach better because MMU relate exception are handled by asm code
* in this file. In compare to with MMU expect of unaligned exception
* is everything handled by C code.
*/
/*
* every of these handlers is entered having R3/4/5/6/11/current saved on stack
* and clobbered so care should be taken to restore them if someone is going to
* return from exception
*/
/* wrappers to restore state before coming to entry.S */
#ifdef CONFIG_MMU
.section .data
.align 4
pt_pool_space:
.space PT_SIZE
#ifdef DEBUG
/* Create space for exception counting. */
.section .data
.global exception_debug_table
.align 4
exception_debug_table:
/* Look at exception vector table. There is 32 exceptions * word size */
.space (32 * 4)
#endif /* DEBUG */
.section .rodata
.align 4
_MB_HW_ExceptionVectorTable:
/* 0 - Undefined */
.long TOPHYS(ex_handler_unhandled)
/* 1 - Unaligned data access exception */
.long TOPHYS(handle_unaligned_ex)
/* 2 - Illegal op-code exception */
.long TOPHYS(full_exception_trapw)
/* 3 - Instruction bus error exception */
.long TOPHYS(full_exception_trapw)
/* 4 - Data bus error exception */
.long TOPHYS(full_exception_trapw)
/* 5 - Divide by zero exception */
.long TOPHYS(full_exception_trapw)
/* 6 - Floating point unit exception */
.long TOPHYS(full_exception_trapw)
/* 7 - Privileged instruction exception */
.long TOPHYS(full_exception_trapw)
/* 8 - 15 - Undefined */
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
/* 16 - Data storage exception */
.long TOPHYS(handle_data_storage_exception)
/* 17 - Instruction storage exception */
.long TOPHYS(handle_instruction_storage_exception)
/* 18 - Data TLB miss exception */
.long TOPHYS(handle_data_tlb_miss_exception)
/* 19 - Instruction TLB miss exception */
.long TOPHYS(handle_instruction_tlb_miss_exception)
/* 20 - 31 - Undefined */
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
.long TOPHYS(ex_handler_unhandled)
#endif
.global _hw_exception_handler
.section .text
.align 4
.ent _hw_exception_handler
_hw_exception_handler:
#ifndef CONFIG_MMU
addik r1, r1, -(EX_HANDLER_STACK_SIZ); /* Create stack frame */
#else
swi r1, r0, TOPHYS(pt_pool_space + PT_R1); /* GET_SP */
/* Save date to kernel memory. Here is the problem
* when you came from user space */
ori r1, r0, TOPHYS(pt_pool_space);
#endif
swi r3, r1, PT_R3
swi r4, r1, PT_R4
swi r5, r1, PT_R5
swi r6, r1, PT_R6
#ifdef CONFIG_MMU
swi r11, r1, PT_R11
swi r31, r1, PT_R31
lwi r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE)) /* get saved current */
#endif
mfs r5, rmsr;
nop
swi r5, r1, 0;
mfs r4, resr
nop
mfs r3, rear;
nop
#ifndef CONFIG_MMU
andi r5, r4, 0x1000; /* Check ESR[DS] */
beqi r5, not_in_delay_slot; /* Branch if ESR[DS] not set */
mfs r17, rbtr; /* ESR[DS] set - return address in BTR */
nop
not_in_delay_slot:
swi r17, r1, PT_R17
#endif
andi r5, r4, 0x1F; /* Extract ESR[EXC] */
#ifdef CONFIG_MMU
/* Calculate exception vector offset = r5 << 2 */
addk r6, r5, r5; /* << 1 */
addk r6, r6, r6; /* << 2 */
#ifdef DEBUG
/* counting which exception happen */
lwi r5, r0, TOPHYS(exception_debug_table)
addi r5, r5, 1
swi r5, r0, TOPHYS(exception_debug_table)
lwi r5, r6, TOPHYS(exception_debug_table)
addi r5, r5, 1
swi r5, r6, TOPHYS(exception_debug_table)
#endif
/* end */
/* Load the HW Exception vector */
lwi r6, r6, TOPHYS(_MB_HW_ExceptionVectorTable)
bra r6
full_exception_trapw:
RESTORE_STATE
bri full_exception_trap
#else
/* Exceptions enabled here. This will allow nested exceptions */
mfs r6, rmsr;
nop
swi r6, r1, 0; /* RMSR_OFFSET */
ori r6, r6, 0x100; /* Turn ON the EE bit */
andi r6, r6, ~2; /* Disable interrupts */
mts rmsr, r6;
nop
xori r6, r5, 1; /* 00001 = Unaligned Exception */
/* Jump to unalignment exception handler */
beqi r6, handle_unaligned_ex;
handle_other_ex: /* Handle Other exceptions here */
/* Save other volatiles before we make procedure calls below */
swi r7, r1, PT_R7
swi r8, r1, PT_R8
swi r9, r1, PT_R9
swi r10, r1, PT_R10
swi r11, r1, PT_R11
swi r12, r1, PT_R12
swi r14, r1, PT_R14
swi r15, r1, PT_R15
swi r18, r1, PT_R18
or r5, r1, r0
andi r6, r4, 0x1F; /* Load ESR[EC] */
lwi r7, r0, PER_CPU(KM) /* MS: saving current kernel mode to regs */
swi r7, r1, PT_MODE
mfs r7, rfsr
nop
addk r8, r17, r0; /* Load exception address */
bralid r15, full_exception; /* Branch to the handler */
nop;
mts rfsr, r0; /* Clear sticky fsr */
nop
/*
* Trigger execution of the signal handler by enabling
* interrupts and calling an invalid syscall.
*/
mfs r5, rmsr;
nop
ori r5, r5, 2;
mts rmsr, r5; /* enable interrupt */
nop
addi r12, r0, __NR_syscalls;
brki r14, 0x08;
mfs r5, rmsr; /* disable interrupt */
nop
andi r5, r5, ~2;
mts rmsr, r5;
nop
lwi r7, r1, PT_R7
lwi r8, r1, PT_R8
lwi r9, r1, PT_R9
lwi r10, r1, PT_R10
lwi r11, r1, PT_R11
lwi r12, r1, PT_R12
lwi r14, r1, PT_R14
lwi r15, r1, PT_R15
lwi r18, r1, PT_R18
bri ex_handler_done; /* Complete exception handling */
#endif
/* 0x01 - Unaligned data access exception
* This occurs when a word access is not aligned on a word boundary,
* or when a 16-bit access is not aligned on a 16-bit boundary.
* This handler perform the access, and returns, except for MMU when
* the unaligned address is last on a 4k page or the physical address is
* not found in the page table, in which case unaligned_data_trap is called.
*/
handle_unaligned_ex:
/* Working registers already saved: R3, R4, R5, R6
* R4 = ESR
* R3 = EAR
*/
#ifdef CONFIG_MMU
andi r6, r4, 0x1000 /* Check ESR[DS] */
beqi r6, _no_delayslot /* Branch if ESR[DS] not set */
mfs r17, rbtr; /* ESR[DS] set - return address in BTR */
nop
_no_delayslot:
/* jump to high level unaligned handler */
RESTORE_STATE;
bri unaligned_data_trap
#endif
andi r6, r4, 0x3E0; /* Mask and extract the register operand */
srl r6, r6; /* r6 >> 5 */
srl r6, r6;
srl r6, r6;
srl r6, r6;
srl r6, r6;
/* Store the register operand in a temporary location */
sbi r6, r0, TOPHYS(ex_reg_op);
andi r6, r4, 0x400; /* Extract ESR[S] */
bnei r6, ex_sw;
ex_lw:
andi r6, r4, 0x800; /* Extract ESR[W] */
beqi r6, ex_lhw;
lbui r5, r3, 0; /* Exception address in r3 */
/* Load a word, byte-by-byte from destination address
and save it in tmp space */
sbi r5, r0, TOPHYS(ex_tmp_data_loc_0);
lbui r5, r3, 1;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_1);
lbui r5, r3, 2;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_2);
lbui r5, r3, 3;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_3);
/* Get the destination register value into r4 */
lwi r4, r0, TOPHYS(ex_tmp_data_loc_0);
bri ex_lw_tail;
ex_lhw:
lbui r5, r3, 0; /* Exception address in r3 */
/* Load a half-word, byte-by-byte from destination
address and save it in tmp space */
sbi r5, r0, TOPHYS(ex_tmp_data_loc_0);
lbui r5, r3, 1;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_1);
/* Get the destination register value into r4 */
lhui r4, r0, TOPHYS(ex_tmp_data_loc_0);
ex_lw_tail:
/* Get the destination register number into r5 */
lbui r5, r0, TOPHYS(ex_reg_op);
/* Form load_word jump table offset (lw_table + (8 * regnum)) */
addik r6, r0, TOPHYS(lw_table);
addk r5, r5, r5;
addk r5, r5, r5;
addk r5, r5, r5;
addk r5, r5, r6;
bra r5;
ex_lw_end: /* Exception handling of load word, ends */
ex_sw:
/* Get the destination register number into r5 */
lbui r5, r0, TOPHYS(ex_reg_op);
/* Form store_word jump table offset (sw_table + (8 * regnum)) */
addik r6, r0, TOPHYS(sw_table);
add r5, r5, r5;
add r5, r5, r5;
add r5, r5, r5;
add r5, r5, r6;
bra r5;
ex_sw_tail:
mfs r6, resr;
nop
andi r6, r6, 0x800; /* Extract ESR[W] */
beqi r6, ex_shw;
/* Get the word - delay slot */
swi r4, r0, TOPHYS(ex_tmp_data_loc_0);
/* Store the word, byte-by-byte into destination address */
lbui r4, r0, TOPHYS(ex_tmp_data_loc_0);
sbi r4, r3, 0;
lbui r4, r0, TOPHYS(ex_tmp_data_loc_1);
sbi r4, r3, 1;
lbui r4, r0, TOPHYS(ex_tmp_data_loc_2);
sbi r4, r3, 2;
lbui r4, r0, TOPHYS(ex_tmp_data_loc_3);
sbi r4, r3, 3;
bri ex_handler_done;
ex_shw:
/* Store the lower half-word, byte-by-byte into destination address */
swi r4, r0, TOPHYS(ex_tmp_data_loc_0);
lbui r4, r0, TOPHYS(ex_tmp_data_loc_2);
sbi r4, r3, 0;
lbui r4, r0, TOPHYS(ex_tmp_data_loc_3);
sbi r4, r3, 1;
ex_sw_end: /* Exception handling of store word, ends. */
ex_handler_done:
#ifndef CONFIG_MMU
lwi r5, r1, 0 /* RMSR */
mts rmsr, r5
nop
lwi r3, r1, PT_R3
lwi r4, r1, PT_R4
lwi r5, r1, PT_R5
lwi r6, r1, PT_R6
lwi r17, r1, PT_R17
rted r17, 0
addik r1, r1, (EX_HANDLER_STACK_SIZ); /* Restore stack frame */
#else
RESTORE_STATE;
rted r17, 0
nop
#endif
#ifdef CONFIG_MMU
/* Exception vector entry code. This code runs with address translation
* turned off (i.e. using physical addresses). */
/* Exception vectors. */
/* 0x10 - 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 heavyweight functions to do the work.
*/
handle_data_storage_exception:
/* Working registers already saved: R3, R4, R5, R6
* R3 = ESR
*/
mfs r11, rpid
nop
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
ori r5, r0, CONFIG_KERNEL_START
cmpu r5, r3, r5
bgti r5, ex3
/* 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_S as well. */
andi r4, r4, 0x800 /* ESR_Z - zone protection */
bnei r4, ex2
ori r4, r0, swapper_pg_dir
mts rpid, r0 /* TLB will have 0 TID */
nop
bri ex4
/* Get the PGD for the current thread. */
ex3:
/* 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_S as well. */
andi r4, r4, 0x800 /* ESR_Z */
bnei r4, ex2
/* get current task address */
addi r4 ,CURRENT_TASK, TOPHYS(0);
lwi r4, r4, TASK_THREAD+PGDIR
ex4:
tophys(r4,r4)
BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */
andi r5, r5, 0xffc
/* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */
or r4, r4, r5
lwi r4, r4, 0 /* Get L1 entry */
andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */
beqi r5, ex2 /* Bail if no table */
tophys(r5,r5)
BSRLI(r6,r3,10) /* Compute PTE address */
andi r6, r6, 0xffc
andi r5, r5, 0xfffff003
or r5, r5, r6
lwi r4, r5, 0 /* Get Linux PTE */
andi r6, r4, _PAGE_RW /* Is it writeable? */
beqi r6, ex2 /* Bail if not */
/* Update 'changed' */
ori r4, r4, _PAGE_DIRTY|_PAGE_ACCESSED|_PAGE_HWWRITE
swi r4, r5, 0 /* 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.
*/
andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
ori r4, r4, _PAGE_HWEXEC /* make it executable */
/* find the TLB index that caused the fault. It has to be here*/
mts rtlbsx, r3
nop
mfs r5, rtlbx /* DEBUG: TBD */
nop
mts rtlblo, r4 /* Load TLB LO */
nop
/* Will sync shadow TLBs */
/* Done...restore registers and get out of here. */
mts rpid, r11
nop
bri 4
RESTORE_STATE;
rted r17, 0
nop
ex2:
/* The bailout. Restore registers to pre-exception conditions
* and call the heavyweights to help us out. */
mts rpid, r11
nop
bri 4
RESTORE_STATE;
bri page_fault_data_trap
/* 0x11 - Instruction Storage Exception
* This is caused by a fetch from non-execute or guarded pages. */
handle_instruction_storage_exception:
/* Working registers already saved: R3, R4, R5, R6
* R3 = ESR
*/
RESTORE_STATE;
bri page_fault_instr_trap
/* 0x12 - 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.
*/
handle_data_tlb_miss_exception:
/* Working registers already saved: R3, R4, R5, R6
* R3 = EAR, R4 = ESR
*/
mfs r11, rpid
nop
/* If we are faulting a kernel address, we have to use the
* kernel page tables. */
ori r6, r0, CONFIG_KERNEL_START
cmpu r4, r3, r6
bgti r4, ex5
ori r4, r0, swapper_pg_dir
mts rpid, r0 /* TLB will have 0 TID */
nop
bri ex6
/* Get the PGD for the current thread. */
ex5:
/* get current task address */
addi r4 ,CURRENT_TASK, TOPHYS(0);
lwi r4, r4, TASK_THREAD+PGDIR
ex6:
tophys(r4,r4)
BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */
andi r5, r5, 0xffc
/* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */
or r4, r4, r5
lwi r4, r4, 0 /* Get L1 entry */
andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */
beqi r5, ex7 /* Bail if no table */
tophys(r5,r5)
BSRLI(r6,r3,10) /* Compute PTE address */
andi r6, r6, 0xffc
andi r5, r5, 0xfffff003
or r5, r5, r6
lwi r4, r5, 0 /* Get Linux PTE */
andi r6, r4, _PAGE_PRESENT
beqi r6, ex7
ori r4, r4, _PAGE_ACCESSED
swi r4, r5, 0
/* 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.
*/
brid finish_tlb_load
andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
ex7:
/* The bailout. Restore registers to pre-exception conditions
* and call the heavyweights to help us out.
*/
mts rpid, r11
nop
bri 4
RESTORE_STATE;
bri page_fault_data_trap
/* 0x13 - Instruction TLB Miss Exception
* Nearly the same as above, except we get our information from
* different registers and bailout to a different point.
*/
handle_instruction_tlb_miss_exception:
/* Working registers already saved: R3, R4, R5, R6
* R3 = ESR
*/
mfs r11, rpid
nop
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
ori r4, r0, CONFIG_KERNEL_START
cmpu r4, r3, r4
bgti r4, ex8
ori r4, r0, swapper_pg_dir
mts rpid, r0 /* TLB will have 0 TID */
nop
bri ex9
/* Get the PGD for the current thread. */
ex8:
/* get current task address */
addi r4 ,CURRENT_TASK, TOPHYS(0);
lwi r4, r4, TASK_THREAD+PGDIR
ex9:
tophys(r4,r4)
BSRLI(r5,r3,20) /* Create L1 (pgdir/pmd) address */
andi r5, r5, 0xffc
/* Assume pgdir aligned on 4K boundary, no need for "andi r4,r4,0xfffff003" */
or r4, r4, r5
lwi r4, r4, 0 /* Get L1 entry */
andi r5, r4, 0xfffff000 /* Extract L2 (pte) base address */
beqi r5, ex10 /* Bail if no table */
tophys(r5,r5)
BSRLI(r6,r3,10) /* Compute PTE address */
andi r6, r6, 0xffc
andi r5, r5, 0xfffff003
or r5, r5, r6
lwi r4, r5, 0 /* Get Linux PTE */
andi r6, r4, _PAGE_PRESENT
beqi r6, ex10
ori r4, r4, _PAGE_ACCESSED
swi r4, r5, 0
/* 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.
*/
brid finish_tlb_load
andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
ex10:
/* The bailout. Restore registers to pre-exception conditions
* and call the heavyweights to help us out.
*/
mts rpid, r11
nop
bri 4
RESTORE_STATE;
bri page_fault_instr_trap
/* Both the instruction and data TLB miss get to this point to load the TLB.
* r3 - EA of fault
* r4 - TLB LO (info from Linux PTE)
* r5, r6 - available to use
* PID - loaded with proper value when we get here
* Upon exit, we reload everything and RFI.
* A common place to load the TLB.
*/
.section .data
.align 4
.global tlb_skip
tlb_skip:
.long MICROBLAZE_TLB_SKIP
tlb_index:
/* MS: storing last used tlb index */
.long MICROBLAZE_TLB_SIZE/2
.previous
finish_tlb_load:
/* MS: load the last used TLB index. */
lwi r5, r0, TOPHYS(tlb_index)
addik r5, r5, 1 /* MS: inc tlb_index -> use next one */
/* MS: FIXME this is potential fault, because this is mask not count */
andi r5, r5, MICROBLAZE_TLB_SIZE - 1
ori r6, r0, 1
cmp r31, r5, r6
blti r31, ex12
lwi r5, r0, TOPHYS(tlb_skip)
ex12:
/* MS: save back current TLB index */
swi r5, r0, TOPHYS(tlb_index)
ori r4, r4, _PAGE_HWEXEC /* make it executable */
mts rtlbx, r5 /* MS: save current TLB */
nop
mts rtlblo, r4 /* MS: save to TLB LO */
nop
/* Create EPN. This is the faulting address plus a static
* set of bits. These are size, valid, E, U0, and ensure
* bits 20 and 21 are zero.
*/
andi r3, r3, 0xfffff000
ori r3, r3, 0x0c0
mts rtlbhi, r3 /* Load TLB HI */
nop
/* Done...restore registers and get out of here. */
mts rpid, r11
nop
bri 4
RESTORE_STATE;
rted r17, 0
nop
/* extern void giveup_fpu(struct task_struct *prev)
*
* The MicroBlaze processor may have an FPU, so this should not just
* return: TBD.
*/
.globl giveup_fpu;
.align 4;
giveup_fpu:
bralid r15,0 /* TBD */
nop
/* At present, this routine just hangs. - extern void abort(void) */
.globl abort;
.align 4;
abort:
br r0
.globl set_context;
.align 4;
set_context:
mts rpid, r5 /* Shadow TLBs are automatically */
nop
bri 4 /* flushed by changing PID */
rtsd r15,8
nop
#endif
.end _hw_exception_handler
#ifdef CONFIG_MMU
/* Unaligned data access exception last on a 4k page for MMU.
* When this is called, we are in virtual mode with exceptions enabled
* and registers 1-13,15,17,18 saved.
*
* R3 = ESR
* R4 = EAR
* R7 = pointer to saved registers (struct pt_regs *regs)
*
* This handler perform the access, and returns via ret_from_exc.
*/
.global _unaligned_data_exception
.ent _unaligned_data_exception
_unaligned_data_exception:
andi r8, r3, 0x3E0; /* Mask and extract the register operand */
BSRLI(r8,r8,2); /* r8 >> 2 = register operand * 8 */
andi r6, r3, 0x400; /* Extract ESR[S] */
bneid r6, ex_sw_vm;
andi r6, r3, 0x800; /* Extract ESR[W] - delay slot */
ex_lw_vm:
beqid r6, ex_lhw_vm;
load1: lbui r5, r4, 0; /* Exception address in r4 - delay slot */
/* Load a word, byte-by-byte from destination address and save it in tmp space*/
addik r6, r0, ex_tmp_data_loc_0;
sbi r5, r6, 0;
load2: lbui r5, r4, 1;
sbi r5, r6, 1;
load3: lbui r5, r4, 2;
sbi r5, r6, 2;
load4: lbui r5, r4, 3;
sbi r5, r6, 3;
brid ex_lw_tail_vm;
/* Get the destination register value into r3 - delay slot */
lwi r3, r6, 0;
ex_lhw_vm:
/* Load a half-word, byte-by-byte from destination address and
* save it in tmp space */
addik r6, r0, ex_tmp_data_loc_0;
sbi r5, r6, 0;
load5: lbui r5, r4, 1;
sbi r5, r6, 1;
lhui r3, r6, 0; /* Get the destination register value into r3 */
ex_lw_tail_vm:
/* Form load_word jump table offset (lw_table_vm + (8 * regnum)) */
addik r5, r8, lw_table_vm;
bra r5;
ex_lw_end_vm: /* Exception handling of load word, ends */
brai ret_from_exc;
ex_sw_vm:
/* Form store_word jump table offset (sw_table_vm + (8 * regnum)) */
addik r5, r8, sw_table_vm;
bra r5;
ex_sw_tail_vm:
addik r5, r0, ex_tmp_data_loc_0;
beqid r6, ex_shw_vm;
swi r3, r5, 0; /* Get the word - delay slot */
/* Store the word, byte-by-byte into destination address */
lbui r3, r5, 0;
store1: sbi r3, r4, 0;
lbui r3, r5, 1;
store2: sbi r3, r4, 1;
lbui r3, r5, 2;
store3: sbi r3, r4, 2;
lbui r3, r5, 3;
brid ret_from_exc;
store4: sbi r3, r4, 3; /* Delay slot */
ex_shw_vm:
/* Store the lower half-word, byte-by-byte into destination address */
#ifdef __MICROBLAZEEL__
lbui r3, r5, 0;
store5: sbi r3, r4, 0;
lbui r3, r5, 1;
brid ret_from_exc;
store6: sbi r3, r4, 1; /* Delay slot */
#else
lbui r3, r5, 2;
store5: sbi r3, r4, 0;
lbui r3, r5, 3;
brid ret_from_exc;
store6: sbi r3, r4, 1; /* Delay slot */
#endif
ex_sw_end_vm: /* Exception handling of store word, ends. */
/* We have to prevent cases that get/put_user macros get unaligned pointer
* to bad page area. We have to find out which origin instruction caused it
* and called fixup for that origin instruction not instruction in unaligned
* handler */
ex_unaligned_fixup:
ori r5, r7, 0 /* setup pointer to pt_regs */
lwi r6, r7, PT_PC; /* faulting address is one instruction above */
addik r6, r6, -4 /* for finding proper fixup */
swi r6, r7, PT_PC; /* a save back it to PT_PC */
addik r7, r0, SIGSEGV
/* call bad_page_fault for finding aligned fixup, fixup address is saved
* in PT_PC which is used as return address from exception */
addik r15, r0, ret_from_exc-8 /* setup return address */
brid bad_page_fault
nop
/* We prevent all load/store because it could failed any attempt to access */
.section __ex_table,"a";
.word load1,ex_unaligned_fixup;
.word load2,ex_unaligned_fixup;
.word load3,ex_unaligned_fixup;
.word load4,ex_unaligned_fixup;
.word load5,ex_unaligned_fixup;
.word store1,ex_unaligned_fixup;
.word store2,ex_unaligned_fixup;
.word store3,ex_unaligned_fixup;
.word store4,ex_unaligned_fixup;
.word store5,ex_unaligned_fixup;
.word store6,ex_unaligned_fixup;
.previous;
.end _unaligned_data_exception
#endif /* CONFIG_MMU */
.global ex_handler_unhandled
ex_handler_unhandled:
/* FIXME add handle function for unhandled exception - dump register */
bri 0
/*
* hw_exception_handler Jump Table
* - Contains code snippets for each register that caused the unalign exception
* - Hence exception handler is NOT self-modifying
* - Separate table for load exceptions and store exceptions.
* - Each table is of size: (8 * 32) = 256 bytes
*/
.section .text
.align 4
lw_table:
lw_r0: R3_TO_LWREG (0);
lw_r1: LWREG_NOP;
lw_r2: R3_TO_LWREG (2);
lw_r3: R3_TO_LWREG_V (3);
lw_r4: R3_TO_LWREG_V (4);
lw_r5: R3_TO_LWREG_V (5);
lw_r6: R3_TO_LWREG_V (6);
lw_r7: R3_TO_LWREG (7);
lw_r8: R3_TO_LWREG (8);
lw_r9: R3_TO_LWREG (9);
lw_r10: R3_TO_LWREG (10);
lw_r11: R3_TO_LWREG (11);
lw_r12: R3_TO_LWREG (12);
lw_r13: R3_TO_LWREG (13);
lw_r14: R3_TO_LWREG (14);
lw_r15: R3_TO_LWREG (15);
lw_r16: R3_TO_LWREG (16);
lw_r17: LWREG_NOP;
lw_r18: R3_TO_LWREG (18);
lw_r19: R3_TO_LWREG (19);
lw_r20: R3_TO_LWREG (20);
lw_r21: R3_TO_LWREG (21);
lw_r22: R3_TO_LWREG (22);
lw_r23: R3_TO_LWREG (23);
lw_r24: R3_TO_LWREG (24);
lw_r25: R3_TO_LWREG (25);
lw_r26: R3_TO_LWREG (26);
lw_r27: R3_TO_LWREG (27);
lw_r28: R3_TO_LWREG (28);
lw_r29: R3_TO_LWREG (29);
lw_r30: R3_TO_LWREG (30);
#ifdef CONFIG_MMU
lw_r31: R3_TO_LWREG_V (31);
#else
lw_r31: R3_TO_LWREG (31);
#endif
sw_table:
sw_r0: SWREG_TO_R3 (0);
sw_r1: SWREG_NOP;
sw_r2: SWREG_TO_R3 (2);
sw_r3: SWREG_TO_R3_V (3);
sw_r4: SWREG_TO_R3_V (4);
sw_r5: SWREG_TO_R3_V (5);
sw_r6: SWREG_TO_R3_V (6);
sw_r7: SWREG_TO_R3 (7);
sw_r8: SWREG_TO_R3 (8);
sw_r9: SWREG_TO_R3 (9);
sw_r10: SWREG_TO_R3 (10);
sw_r11: SWREG_TO_R3 (11);
sw_r12: SWREG_TO_R3 (12);
sw_r13: SWREG_TO_R3 (13);
sw_r14: SWREG_TO_R3 (14);
sw_r15: SWREG_TO_R3 (15);
sw_r16: SWREG_TO_R3 (16);
sw_r17: SWREG_NOP;
sw_r18: SWREG_TO_R3 (18);
sw_r19: SWREG_TO_R3 (19);
sw_r20: SWREG_TO_R3 (20);
sw_r21: SWREG_TO_R3 (21);
sw_r22: SWREG_TO_R3 (22);
sw_r23: SWREG_TO_R3 (23);
sw_r24: SWREG_TO_R3 (24);
sw_r25: SWREG_TO_R3 (25);
sw_r26: SWREG_TO_R3 (26);
sw_r27: SWREG_TO_R3 (27);
sw_r28: SWREG_TO_R3 (28);
sw_r29: SWREG_TO_R3 (29);
sw_r30: SWREG_TO_R3 (30);
#ifdef CONFIG_MMU
sw_r31: SWREG_TO_R3_V (31);
#else
sw_r31: SWREG_TO_R3 (31);
#endif
#ifdef CONFIG_MMU
lw_table_vm:
lw_r0_vm: R3_TO_LWREG_VM (0);
lw_r1_vm: R3_TO_LWREG_VM_V (1);
lw_r2_vm: R3_TO_LWREG_VM_V (2);
lw_r3_vm: R3_TO_LWREG_VM_V (3);
lw_r4_vm: R3_TO_LWREG_VM_V (4);
lw_r5_vm: R3_TO_LWREG_VM_V (5);
lw_r6_vm: R3_TO_LWREG_VM_V (6);
lw_r7_vm: R3_TO_LWREG_VM_V (7);
lw_r8_vm: R3_TO_LWREG_VM_V (8);
lw_r9_vm: R3_TO_LWREG_VM_V (9);
lw_r10_vm: R3_TO_LWREG_VM_V (10);
lw_r11_vm: R3_TO_LWREG_VM_V (11);
lw_r12_vm: R3_TO_LWREG_VM_V (12);
lw_r13_vm: R3_TO_LWREG_VM_V (13);
lw_r14_vm: R3_TO_LWREG_VM_V (14);
lw_r15_vm: R3_TO_LWREG_VM_V (15);
lw_r16_vm: R3_TO_LWREG_VM_V (16);
lw_r17_vm: R3_TO_LWREG_VM_V (17);
lw_r18_vm: R3_TO_LWREG_VM_V (18);
lw_r19_vm: R3_TO_LWREG_VM_V (19);
lw_r20_vm: R3_TO_LWREG_VM_V (20);
lw_r21_vm: R3_TO_LWREG_VM_V (21);
lw_r22_vm: R3_TO_LWREG_VM_V (22);
lw_r23_vm: R3_TO_LWREG_VM_V (23);
lw_r24_vm: R3_TO_LWREG_VM_V (24);
lw_r25_vm: R3_TO_LWREG_VM_V (25);
lw_r26_vm: R3_TO_LWREG_VM_V (26);
lw_r27_vm: R3_TO_LWREG_VM_V (27);
lw_r28_vm: R3_TO_LWREG_VM_V (28);
lw_r29_vm: R3_TO_LWREG_VM_V (29);
lw_r30_vm: R3_TO_LWREG_VM_V (30);
lw_r31_vm: R3_TO_LWREG_VM_V (31);
sw_table_vm:
sw_r0_vm: SWREG_TO_R3_VM (0);
sw_r1_vm: SWREG_TO_R3_VM_V (1);
sw_r2_vm: SWREG_TO_R3_VM_V (2);
sw_r3_vm: SWREG_TO_R3_VM_V (3);
sw_r4_vm: SWREG_TO_R3_VM_V (4);
sw_r5_vm: SWREG_TO_R3_VM_V (5);
sw_r6_vm: SWREG_TO_R3_VM_V (6);
sw_r7_vm: SWREG_TO_R3_VM_V (7);
sw_r8_vm: SWREG_TO_R3_VM_V (8);
sw_r9_vm: SWREG_TO_R3_VM_V (9);
sw_r10_vm: SWREG_TO_R3_VM_V (10);
sw_r11_vm: SWREG_TO_R3_VM_V (11);
sw_r12_vm: SWREG_TO_R3_VM_V (12);
sw_r13_vm: SWREG_TO_R3_VM_V (13);
sw_r14_vm: SWREG_TO_R3_VM_V (14);
sw_r15_vm: SWREG_TO_R3_VM_V (15);
sw_r16_vm: SWREG_TO_R3_VM_V (16);
sw_r17_vm: SWREG_TO_R3_VM_V (17);
sw_r18_vm: SWREG_TO_R3_VM_V (18);
sw_r19_vm: SWREG_TO_R3_VM_V (19);
sw_r20_vm: SWREG_TO_R3_VM_V (20);
sw_r21_vm: SWREG_TO_R3_VM_V (21);
sw_r22_vm: SWREG_TO_R3_VM_V (22);
sw_r23_vm: SWREG_TO_R3_VM_V (23);
sw_r24_vm: SWREG_TO_R3_VM_V (24);
sw_r25_vm: SWREG_TO_R3_VM_V (25);
sw_r26_vm: SWREG_TO_R3_VM_V (26);
sw_r27_vm: SWREG_TO_R3_VM_V (27);
sw_r28_vm: SWREG_TO_R3_VM_V (28);
sw_r29_vm: SWREG_TO_R3_VM_V (29);
sw_r30_vm: SWREG_TO_R3_VM_V (30);
sw_r31_vm: SWREG_TO_R3_VM_V (31);
#endif /* CONFIG_MMU */
/* Temporary data structures used in the handler */
.section .data
.align 4
ex_tmp_data_loc_0:
.byte 0
ex_tmp_data_loc_1:
.byte 0
ex_tmp_data_loc_2:
.byte 0
ex_tmp_data_loc_3:
.byte 0
ex_reg_op:
.byte 0
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