source: mainline/arch/mips32/src/exception.c@ e07fe0c

/*
 * Copyright (C) 2003-2004 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>
#include <debug.h>
#include <proc/thread.h>
#include <symtab.h>
#include <print.h>
#include <interrupt.h>
#include <func.h>
#include <console/kconsole.h>

static char * exctable[] = {
        "Interrupt","TLB Modified","TLB Invalid","TLB Invalid Store",
                "Address Error - load/instr. fetch",
                "Address Error - store",
                "Bus Error - fetch instruction",
                "Bus Error - data reference",
                "Syscall",
                "BreakPoint",
                "Reserved Instruction",
                "Coprocessor Unusable",
                "Arithmetic Overflow",
                "Trap",
                "Virtual Coherency - instruction",
                "Floating Point",
                NULL, NULL, NULL, NULL, NULL, NULL, NULL,
                "WatchHi/WatchLo", /* 23 */
                NULL, NULL, NULL, NULL, NULL, NULL, NULL,
                "Virtual Coherency - data",
};

static void print_regdump(struct exception_regdump *pstate)
{
        char *pcsymbol = "";
        char *rasymbol = "";

        char *s = get_symtab_entry(pstate->epc);
        if (s)
                pcsymbol = s;
        s = get_symtab_entry(pstate->ra);
        if (s)
                rasymbol = s;
        
        printf("PC: %X(%s) RA: %X(%s)\n",pstate->epc,pcsymbol,
               pstate->ra,rasymbol);
}

static void unhandled_exception(int n, void *data)
{
        struct exception_regdump *pstate = (struct exception_regdump *)data;

        print_regdump(pstate);
        panic("unhandled exception %s\n", exctable[n]);
}

static void breakpoint_exception(int n, void *data)
{
        struct exception_regdump *pstate = (struct exception_regdump *)data;
        char *symbol = get_symtab_entry(pstate->epc);

#ifdef CONFIG_DEBUG     
        printf("***Breakpoint %p in %s.\n", pstate->epc, symbol);
        printf("***Type 'exit' to exit kconsole.\n");
        /* Umm..we should rather set some 'debugstate' here */
        haltstate = 1;
        kconsole("debug");
        haltstate = 0;
#endif

        /* it is necessary to not re-execute BREAK instruction after 
           returning from Exception handler
           (see page 138 in R4000 Manual for more information) */
        pstate->epc += 4;
}

static void tlbmod_exception(int n, void *data)
{
        struct exception_regdump *pstate = (struct exception_regdump *)data;
        tlb_modified(pstate);
}

static void tlbinv_exception(int n, void *data)
{
        struct exception_regdump *pstate = (struct exception_regdump *)data;
        tlb_invalid(pstate);
}

static void cpuns_exception(int n, void *data)
{
        if (cp0_cause_coperr(cp0_cause_read()) == fpu_cop_id)
                scheduler_fpu_lazy_request();
        else
                panic("unhandled Coprocessor Unusable Exception\n");
}

static void interrupt_exception(int n, void *pstate)
{
        __u32 cause;
        int i;
        
        /* decode interrupt number and process the interrupt */
        cause = (cp0_cause_read() >> 8) &0xff;
        
        for (i = 0; i < 8; i++)
                if (cause & (1 << i))
                        exc_dispatch(i+INT_OFFSET, pstate);
}


void exception(struct exception_regdump *pstate)
{
        int cause;
        int excno;
        __u32 epc_shift = 0;

        ASSERT(CPU != NULL);

        /*
         * NOTE ON OPERATION ORDERING
         *
         * On entry, interrupts_disable() must be called before 
         * exception bit is cleared.
         */

        interrupts_disable();
        cp0_status_write(cp0_status_read() & ~ (cp0_status_exl_exception_bit |
                                                cp0_status_um_bit));

        /* Save pstate so that the threads can access it */
        /* If THREAD->pstate is set, this is nested exception,
         * do not rewrite it
         */
        if (THREAD && !THREAD->pstate)
                THREAD->pstate = pstate;

        cause = cp0_cause_read();
        excno = cp0_cause_excno(cause);
        /* Dispatch exception */
        exc_dispatch(excno, pstate);

        /* Set to NULL, so that we can still support nested
         * exceptions
         * TODO: We should probably set EXL bit before this command,
         * nesting. On the other hand, if some exception occurs between
         * here and ERET, it won't set anything on the pstate anyway.
         */
        if (THREAD)
                THREAD->pstate = NULL;
}

void exception_init(void)
{
        int i;

        /* Clear exception table */
        for (i=0;i < IVT_ITEMS; i++)
                exc_register(i, "undef", unhandled_exception);
        exc_register(EXC_Bp, "bkpoint", breakpoint_exception);
        exc_register(EXC_Mod, "tlb_mod", tlbmod_exception);
        exc_register(EXC_TLBL, "tlbinvl", tlbinv_exception);
        exc_register(EXC_TLBS, "tlbinvl", tlbinv_exception);
        exc_register(EXC_Int, "interrupt", interrupt_exception);
#ifdef CONFIG_FPU_LAZY
        exc_register(EXC_CpU, "cpunus", cpuns_exception);
#endif
}