usr/src/sys/i386/i386/kgdb_glue.c

/*
 * Copyright (c) 1991 Regents of the University of California.
 * All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Lawrence Berkeley Laboratories.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)kgdb_glue.c 7.4 (Berkeley) %G%
 */

/*
 * This file must be compiled with gcc -fno-defer-pop.
 */

#ifdef KGDB

#include <sys/param.h>
#include <machine/frame.h>
#include <machine/reg.h>

#ifndef lint
static char rcsid[] =
    "@(#) $Header: /u/donn/c/gdb/kernel/RCS/kgdb_glue.c,v 1.2 91/03/31 16:04:52 donn Exp Locker: donn $ (LBL)";
#endif

#define KGDB_STACKSIZE 0x800
#define KGDB_STACKWORDS (KGDB_STACKSIZE / sizeof(u_long))

u_long kgdb_stack[KGDB_STACKWORDS];

#define getsp(v) asm volatile ("movl %%esp,%0" : "=r" (v))
#define setsp(v) asm volatile ("movl %0,%%esp" :: "r" (v))

static inline void
copywords(src, dst, nbytes)
        register u_long *src, *dst;
        register u_int nbytes;
{
        u_long *limit = src + (nbytes / sizeof(u_long));

        do {
                *dst++ = *src++;
        } while (src < limit);
        if (nbytes & 2)
                *(u_short *)dst = *(u_short *)src;
}

kgdb_trap_glue(frame)
        struct trapframe frame;
{
        u_long osp, nsp;
        u_int s;

        /*
         * On internal traps, the hardware doesn't push ss and esp.
         */
        u_int fsize = sizeof frame - 2 * sizeof (int);
#ifdef DONN
        extern int kgdb_debug;

        if (kgdb_debug > 3)
                pg("kgdb_trap_glue: entered, fsize = %d\n", fsize);
#endif

        /*
         * After a kernel mode trap, the saved sp doesn't point to the right
         * place.  The correct value is the top of the frame.
         */
        frame.tf_isp = (u_long)(&frame) + fsize;

        /*
         * Copy the interrupt context and frame to the new stack.
         * We're throwing away trap()'s frame since we're going to do
         * our own iret.
         */
        nsp = (u_long)(&kgdb_stack[KGDB_STACKWORDS]) - fsize;

        copywords((u_long *)&frame, (u_long *)nsp, fsize);

        s = splhigh();

        getsp(osp);
        setsp(nsp);

        if (kgdb_trap(frame.tf_trapno, (struct frame *)nsp) == 0) {
                /*
                 * Get back on kernel stack.  This thread of control
                 * will return back up through trap().  If kgdb_trap()
                 * returns 0, it didn't handle the trap at all so
                 * the stack is still intact and everything will
                 * unwind okay from here up.
                 */
                setsp(osp);
                splx(s);
                return 0;
        }

        /*
         * Copy back context, which has possibly changed.  Even the
         * sp might have changed.
         */
        osp = ((struct trapframe *)nsp)->tf_isp - fsize;
        copywords((u_long *)nsp, (u_long *)osp, fsize);
        setsp(osp);

        /*
         * Restore the possible new context from frame.
         */
        asm volatile ("pop %es; pop %ds; popal; nop; addl $8,%esp; iret");
}

int kgdb_testval;

kgdb_test(i)
{
        ++kgdb_testval;
        return i + 1;
}

#endif