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-rw-r--r--arch/microblaze/kernel/hw_exception_handler.S458
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diff --git a/arch/microblaze/kernel/hw_exception_handler.S b/arch/microblaze/kernel/hw_exception_handler.S
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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
+ *
+ * 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 */
+#define EX_HANDLER_STACK_SIZ (4*19)
+#define NUM_TO_REG(num) r ## num
+
+#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;
+
+.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 */
+
+.global _hw_exception_handler
+.section .text
+.align 4
+.ent _hw_exception_handler
+_hw_exception_handler:
+ addik r1, r1, -(EX_HANDLER_STACK_SIZ); /* Create stack frame */
+ swi r3, r1, PT_R3
+ swi r4, r1, PT_R4
+ swi r5, r1, PT_R5
+ swi r6, r1, PT_R6
+
+ mfs r5, rmsr;
+ nop
+ swi r5, r1, 0;
+ mfs r4, rbtr /* Save BTR before jumping to handler */
+ nop
+ mfs r3, resr
+ nop
+
+ 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
+
+ andi r5, r3, 0x1F; /* Extract ESR[EXC] */
+
+ /* 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 */
+
+/* 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 = BTR
+ */
+ mfs r4, rear;
+ nop
+
+ 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);
+
+ 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:
+ 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 */
+
+.end _hw_exception_handler
+
+ex_handler_unhandled:
+/* FIXME add handle function for unhandled exception - dump register */
+ bri 0
+
+.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 (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 (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
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