kvisc/vm/pc/except.c

// The OS/K Team licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

#include <pc/device.h>

int dying = 0;

void _except(ctx_t *ctx, int _code, char *fmt, ...)
{
    va_list ap;
    ulong handler;
    uint code = _code;
    uint effcode;

    ulong orig_frame;

    //
    // Interrupted earlier?
    //

    if (dying)
    {
        logerr("Exception thrown while dying=1\n");
        exit(-12);
    }

    if (code >= IDT_SLOTS || code == 1023)
        goto actually_die;

    //
    // Check for E/I handlers
    //
    if (idt[code] == 0)
    {
        if (code == E_DBF)
            effcode = E_DBF;

        else if (code < 512)
            effcode = 0;

        else if (code < 768)
            effcode = 512;

        else
            effcode = 768;
    }

    else
        effcode = code;

    handler = idt[effcode];

    // Found nothing?
    if (handler == 0)
        goto actually_die; // oh well

    // Is another handler already running?
    if (idt_handling[code] > 0)
    {
        // Triple fault?
        if (code == E_DBF)
            goto actually_die;

        // Double fault then?
        if (code < 512)
            _except(ctx, E_DBF, "Double Fault; previously handling: #%u", code);

        // Todo: queue INTs
        else
            goto actually_die;
    }

    // Is this a valid frame?
    if (rfs[handler] != NULL)
    {
        if (ctx->dumpsw)
        {
            trace("\nException %u - ", code);

            va_start(ap, fmt);
            vprintf(fmt, ap);
            va_end(ap);

            trace("\n\n");
        }

        orig_frame = rfs_current_idx;

        ctx->rf = rfs[handler];
        rfs_current_idx = handler;

        R(R12) = code;
        R(R13) = effcode;
        R(R14) = orig_frame;
        R(R15) = R(RIP);

        idt_handling[effcode]++;

        longjmp(exc_jmp_buf, code);

        __builtin_unreachable();
    }

actually_die:
    logerr("\nException %u - ", code);

    va_start(ap, fmt);
    vfprintf(stderr, fmt, ap);
    va_end(ap);

    logerr("\n\n");

    dying = 1;

    dumpregs(ctx);
    logerr("\n");

    die(code);
}