source: mainline/arch/mips/src/exception.c@ 9c0a9b3

/*
 * Copyright (C) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <arch/exception.h>
#include <arch/interrupt.h>
#include <panic.h>
#include <arch/cp0.h>
#include <arch/types.h>
#include <arch.h>

void exception(void)
{
        int excno;
        __u32 epc;
        __u32 epc_shift = 0;
        pri_t pri;
        
        pri = cpu_priority_high();
        epc = cp0_epc_read();
        cp0_status_write(cp0_status_read() & ~ cp0_status_exl_exception_bit);

        if (THREAD) {
                THREAD->saved_pri = pri;
                THREAD->saved_epc = epc;
        }
        /* decode exception number and process the exception */
        switch (excno = (cp0_cause_read() >> 2) & 0x1f) {
                case EXC_Int:
                        interrupt();
                        break;
                case EXC_TLBL:
                case EXC_TLBS:
                        tlb_invalid();
                        break;
                case EXC_Mod:
                        panic("unhandled TLB Modification Exception\n");
                        break;
                case EXC_AdEL:
                        panic("unhandled Address Error Exception - load or instruction fetch\n");
                        break;
                case EXC_AdES:
                        panic("unhandled Address Error Exception - store\n");
                        break;
                case EXC_IBE:
                        panic("unhandled Bus Error Exception - fetch instruction\n");
                        break;
                case EXC_DBE:
                        panic("unhandled Bus Error Exception - data reference: load or store\n");
                        break;
                case EXC_Bp:
                        /* it is necessary to not re-execute BREAK instruction after returning from Exception handler
                           (see page 138 in R4000 Manual for more information) */
                        epc_shift = 4;
                        break;
                case EXC_RI:
                        panic("unhandled Reserved Instruction Exception\n");
                        break;
                case EXC_CpU:
                        panic("unhandled Coprocessor Unusable Exception\n");
                        break;
                case EXC_Ov:
                        panic("unhandled Arithmetic Overflow Exception\n");
                        break;
                case EXC_Tr:
                        panic("unhandled Trap Exception\n");
                        break;
                case EXC_VCEI:
                        panic("unhandled Virtual Coherency Exception - instruction\n");
                        break;
                case EXC_FPE:
                        panic("unhandled Floating-Point Exception\n");
                        break;
                case EXC_WATCH:
                        panic("unhandled reference to WatchHi/WatchLo address\n");
                        break;
                case EXC_VCED:
                        panic("unhandled Virtual Coherency Exception - data\n");
                        break;
                default:
                        panic("unhandled exception %d\n", excno);
        }
        
        if (THREAD) {
                pri = THREAD->saved_pri;
                epc = THREAD->saved_epc;
        }

        cp0_epc_write(epc + epc_shift);
        cp0_status_write(cp0_status_read() | cp0_status_exl_exception_bit);
        cpu_priority_restore(pri);
}