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+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * 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.
+ */
+
+/*
+ * 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 <linux/pgtable.h>
+
+#include <asm/mmu.h>
+#include <asm/signal.h>
+#include <asm/registers.h>
+#include <asm/asm-offsets.h>
+
+#undef DEBUG
+
+/* Helpful Macros */
+#define NUM_TO_REG(num) r ## num
+
+ #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;
+
+#define LWREG_NOP \
+ bri ex_handler_unhandled; \
+ nop;
+
+#define SWREG_NOP \
+ bri ex_handler_unhandled; \
+ nop;
+
+/* 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;
+
+ #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
+ /* Only the used shift constants defined here - add more if needed */
+ #define BSRLI2(rD, rA) \
+ srl rD, rA; /* << 1 */ \
+ srl rD, rD; /* << 2 */
+ #define BSRLI4(rD, rA) \
+ BSRLI2(rD, rA); \
+ BSRLI2(rD, rD)
+ #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)
+
+ .macro bsrli, rD, rA, IMM
+ .if (\IMM) == 2
+ BSRLI2(\rD, \rA)
+ .elseif (\IMM) == 10
+ BSRLI10(\rD, \rA)
+ .elseif (\IMM) == 12
+ BSRLI2(\rD, \rA)
+ BSRLI10(\rD, \rD)
+ .elseif (\IMM) == 14
+ BSRLI4(\rD, \rA)
+ BSRLI10(\rD, \rD)
+ .elseif (\IMM) == 20
+ BSRLI20(\rD, \rA)
+ .elseif (\IMM) == 24
+ BSRLI4(\rD, \rA)
+ BSRLI20(\rD, \rD)
+ .elseif (\IMM) == 28
+ BSRLI4(\rD, \rA)
+ BSRLI4(\rD, \rD)
+ BSRLI20(\rD, \rD)
+ .else
+ .error "BSRLI shift macros \IMM"
+ .endif
+ .endm
+ #endif
+
+
+.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 CONFIG_MMU=n)
+ * ----------------------------------------
+ *
+ * +-------------+ + 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 */
+.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)
+
+.global _hw_exception_handler
+.section .text
+.align 4
+.ent _hw_exception_handler
+_hw_exception_handler:
+ 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);
+ swi r3, r1, PT_R3
+ swi r4, r1, PT_R4
+ swi r5, r1, PT_R5
+ swi r6, r1, PT_R6
+
+ swi r11, r1, PT_R11
+ swi r31, r1, PT_R31
+ lwi r31, r0, TOPHYS(PER_CPU(CURRENT_SAVE)) /* get saved current */
+
+ mfs r5, rmsr;
+ nop
+ swi r5, r1, 0;
+ mfs r4, resr
+ nop
+ mfs r3, rear;
+ nop
+
+ andi r5, r4, 0x1F; /* Extract ESR[EXC] */
+
+ /* 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
+
+/* 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
+ */
+ 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
+
+ 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:
+ RESTORE_STATE;
+ rted r17, 0
+ nop
+
+ /* 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, ESR_DIZ /* 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, ESR_DIZ /* 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)
+ /* Create L1 (pgdir/pmd) address */
+ bsrli r5, r3, PGDIR_SHIFT - 2
+ andi r5, r5, PAGE_SIZE - 4
+/* 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, PAGE_MASK /* Extract L2 (pte) base address */
+ beqi r5, ex2 /* Bail if no table */
+
+ tophys(r5,r5)
+ bsrli r6, r3, PTE_SHIFT /* Compute PTE address */
+ andi r6, r6, PAGE_SIZE - 4
+ 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.
+ */
+/* Ignore memory coherent, just LSB on ZSEL is used + EX/WR */
+ andi r4, r4, PAGE_MASK | TLB_EX | TLB_WR | \
+ TLB_ZSEL(1) | TLB_ATTR_MASK
+ 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)
+ /* Create L1 (pgdir/pmd) address */
+ bsrli r5, r3, PGDIR_SHIFT - 2
+ andi r5, r5, PAGE_SIZE - 4
+/* 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, PAGE_MASK /* Extract L2 (pte) base address */
+ beqi r5, ex7 /* Bail if no table */
+
+ tophys(r5,r5)
+ bsrli r6, r3, PTE_SHIFT /* Compute PTE address */
+ andi r6, r6, PAGE_SIZE - 4
+ 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
+ andi r4, r4, PAGE_MASK | TLB_EX | TLB_WR | \
+ TLB_ZSEL(1) | TLB_ATTR_MASK
+ 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)
+ /* Create L1 (pgdir/pmd) address */
+ bsrli r5, r3, PGDIR_SHIFT - 2
+ andi r5, r5, PAGE_SIZE - 4
+/* 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, PAGE_MASK /* Extract L2 (pte) base address */
+ beqi r5, ex10 /* Bail if no table */
+
+ tophys(r5,r5)
+ bsrli r6, r3, PTE_SHIFT /* Compute PTE address */
+ andi r6, r6, PAGE_SIZE - 4
+ 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
+ andi r4, r4, PAGE_MASK | TLB_EX | TLB_WR | \
+ TLB_ZSEL(1) | TLB_ATTR_MASK
+ 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, PAGE_MASK
+ ori r3, r3, TLB_VALID | TLB_PAGESZ(PAGESZ_4K)
+ 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
+
+.end _hw_exception_handler
+
+/* 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
+
+.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);
+lw_r31: R3_TO_LWREG_V (31);
+
+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);
+sw_r31: SWREG_TO_R3_V (31);
+
+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);
+
+/* 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