/*
* 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/asm-offsets.h>
/* Helpful Macros */
#ifndef CONFIG_MMU
#define EX_HANDLER_STACK_SIZ (4*19)
#endif
#define NUM_TO_REG(num) r ## num
#ifdef CONFIG_MMU
/* FIXME you can't change first load of MSR because there is
* hardcoded jump bri 4 */
#define RESTORE_STATE \
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, r0, TOPHYS(r0_ram + 0);
#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
#elif CONFIG_XILINX_MICROBLAZE0_USE_DIV > 0
#define BSRLI(rD, rA, imm) \
ori rD, r0, (1 << imm); \
idivu rD, rD, rA
#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
* | . |
* | . |
*
* NO_MMU kernel use the same r0_ram pointed space - look to vmlinux.lds.S
* which is used for storing register values - old style was, that value 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 .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(r0_ram + 0); /* GET_SP */
/* Save date to kernel memory. Here is the problem
* when you came from user space */
ori r1, r0, TOPHYS(r0_ram + 28);
#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 r3, resr
nop
mfs r4, rear;
nop
#ifndef CONFIG_MMU
andi r5, r3, 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, r3, 0x1F; /* Extract ESR[EXC] */
#ifdef CONFIG_MMU
/* Calculate exception vector offset = r5 << 2 */
addk r6, r5, r5; /* << 1 */
addk r6, r6, r6; /* << 2 */
/* counting which exception happen */
lwi r5, r0, 0x200 + TOPHYS(r0_ram)
addi r5, r5, 1
swi r5, r0, 0x200 + TOPHYS(r0_ram)
lwi r5, r6, 0x200 + TOPHYS(r0_ram)
addi r5, r5, 1
swi r5, r6, 0x200 + TOPHYS(r0_ram)
/* 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, r3, 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;
/*
* 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
* R3 = ESR
* R4 = EAR
*/
#ifdef CONFIG_MMU
andi r6, r3, 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:
#endif
#ifdef CONFIG_MMU
/* Check if unaligned address is last on a 4k page */
andi r5, r4, 0xffc
xori r5, r5, 0xffc
bnei r5, _unaligned_ex2
_unaligned_ex1:
RESTORE_STATE;
/* Another page must be accessed or physical address not in page table */
bri unaligned_data_trap
_unaligned_ex2:
#endif
andi r6, r3, 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);
#ifdef CONFIG_MMU
/* Get physical address */
/* If we are faulting a kernel address, we have to use the
* kernel page tables.
*/
ori r5, r0, CONFIG_KERNEL_START
cmpu r5, r4, r5
bgti r5, _unaligned_ex3
ori r5, r0, swapper_pg_dir
bri _unaligned_ex4
/* Get the PGD for the current thread. */
_unaligned_ex3: /* user thread */
addi r5 ,CURRENT_TASK, TOPHYS(0); /* get current task address */
lwi r5, r5, TASK_THREAD + PGDIR
_unaligned_ex4:
tophys(r5,r5)
BSRLI(r6,r4,20) /* Create L1 (pgdir/pmd) address */
andi r6, r6, 0xffc
/* Assume pgdir aligned on 4K boundary, no need for "andi r5,r5,0xfffff003" */
or r5, r5, r6
lwi r6, r5, 0 /* Get L1 entry */
andi r5, r6, 0xfffff000 /* Extract L2 (pte) base address. */
beqi r5, _unaligned_ex1 /* Bail if no table */
tophys(r5,r5)
BSRLI(r6,r4,10) /* Compute PTE address */
andi r6, r6, 0xffc
andi r5, r5, 0xfffff003
or r5, r5, r6
lwi r5, r5, 0 /* Get Linux PTE */
andi r6, r5, _PAGE_PRESENT
beqi r6, _unaligned_ex1 /* Bail if no page */
andi r5, r5, 0xfffff000 /* Extract RPN */
andi r4, r4, 0x00000fff /* Extract offset */
or r4, r4, r5 /* Create physical address */
#endif /* CONFIG_MMU */
andi r6, r3, 0x400; /* Extract ESR[S] */
bnei r6, ex_sw;
ex_lw:
andi r6, r3, 0x800; /* Extract ESR[W] */
beqi r6, ex_lhw;
lbui r5, r4, 0; /* Exception address in r4 */
/* 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, r4, 1;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_1);
lbui r5, r4, 2;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_2);
lbui r5, r4, 3;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_3);
/* Get the destination register value into r3 */
lwi r3, r0, TOPHYS(ex_tmp_data_loc_0);
bri ex_lw_tail;
ex_lhw:
lbui r5, r4, 0; /* Exception address in r4 */
/* 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, r4, 1;
sbi r5, r0, TOPHYS(ex_tmp_data_loc_1);
/* Get the destination register value into r3 */
lhui r3, 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)) */
la 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)) */
la 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 r3, r0, TOPHYS(ex_tmp_data_loc_0);
/* Store the word, byte-by-byte into destination address */
lbui r3, r0, TOPHYS(ex_tmp_data_loc_0);
sbi r3, r4, 0;
lbui r3, r0, TOPHYS(ex_tmp_data_loc_1);
sbi r3, r4, 1;
lbui r3, r0, TOPHYS(ex_tmp_data_loc_2);
sbi r3, r4, 2;
lbui r3, r0, TOPHYS(ex_tmp_data_loc_3);
sbi r3, r4, 3;
bri ex_handler_done;
ex_shw:
/* Store the lower half-word, byte-by-byte into destination address */
swi r3, r0, TOPHYS(ex_tmp_data_loc_0);
lbui r3, r0, TOPHYS(ex_tmp_data_loc_2);
sbi r3, r4, 0;
lbui r3, r0, TOPHYS(ex_tmp_data_loc_3);
sbi r3, r4, 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
bri 4
mfs r3, rear /* Get faulting address */
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, 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. */
mfs r4, resr
nop
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. */
mfs r4, resr
nop
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
*/
mfs r3, rear /* Get faulting address */
nop
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 = ESR
*/
mfs r11, rpid
nop
bri 4
mfs r3, rear /* Get faulting address */
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, 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.
*/
andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
bri finish_tlb_load
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
bri 4
mfs r3, rear /* Get faulting address */
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, 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.
*/
andni r4, r4, 0x0ce2 /* Make sure 20, 21 are zero */
bri finish_tlb_load
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.
*/
tlb_index:
.long 1 /* MS: storing last used tlb index */
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, sem
addik r5, r6, 1
sem:
/* 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. */
ex12:
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;
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*/
la r6, r0, ex_tmp_data_loc_0;
sbi r5, r6, 0;
lbui r5, r4, 1;
sbi r5, r6, 1;
lbui r5, r4, 2;
sbi r5, r6, 2;
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 */
la r6, r0, ex_tmp_data_loc_0;
sbi r5, r6, 0;
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:
la 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;
sbi r3, r4, 0;
lbui r3, r5, 1;
sbi r3, r4, 1;
lbui r3, r5, 2;
sbi r3, r4, 2;
lbui r3, r5, 3;
brid ret_from_exc;
sbi r3, r4, 3; /* Delay slot */
ex_shw_vm:
/* Store the lower half-word, byte-by-byte into destination address */
lbui r3, r5, 2;
sbi r3, r4, 0;
lbui r3, r5, 3;
brid ret_from_exc;
sbi r3, r4, 1; /* Delay slot */
ex_sw_end_vm: /* Exception handling of store word, ends. */
.end _unaligned_data_exception
#endif /* CONFIG_MMU */
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 (14);
lw_r15_vm: R3_TO_LWREG_VM_V (15);
lw_r16_vm: R3_TO_LWREG_VM (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 (19);
lw_r20_vm: R3_TO_LWREG_VM (20);
lw_r21_vm: R3_TO_LWREG_VM (21);
lw_r22_vm: R3_TO_LWREG_VM (22);
lw_r23_vm: R3_TO_LWREG_VM (23);
lw_r24_vm: R3_TO_LWREG_VM (24);
lw_r25_vm: R3_TO_LWREG_VM (25);
lw_r26_vm: R3_TO_LWREG_VM (26);
lw_r27_vm: R3_TO_LWREG_VM (27);
lw_r28_vm: R3_TO_LWREG_VM (28);
lw_r29_vm: R3_TO_LWREG_VM (29);
lw_r30_vm: R3_TO_LWREG_VM (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 (14);
sw_r15_vm: SWREG_TO_R3_VM_V (15);
sw_r16_vm: SWREG_TO_R3_VM (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 (19);
sw_r20_vm: SWREG_TO_R3_VM (20);
sw_r21_vm: SWREG_TO_R3_VM (21);
sw_r22_vm: SWREG_TO_R3_VM (22);
sw_r23_vm: SWREG_TO_R3_VM (23);
sw_r24_vm: SWREG_TO_R3_VM (24);
sw_r25_vm: SWREG_TO_R3_VM (25);
sw_r26_vm: SWREG_TO_R3_VM (26);
sw_r27_vm: SWREG_TO_R3_VM (27);
sw_r28_vm: SWREG_TO_R3_VM (28);
sw_r29_vm: SWREG_TO_R3_VM (29);
sw_r30_vm: SWREG_TO_R3_VM (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
