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      1 /*	$NetBSD: kgdb_glue.c,v 1.10 2007/10/17 19:58:04 garbled Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This software was developed by the Computer Systems Engineering group
      8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      9  * contributed to Berkeley.
     10  *
     11  * All advertising materials mentioning features or use of this software
     12  * must display the following acknowledgement:
     13  *	This product includes software developed by the University of
     14  *	California, Lawrence Berkeley Laboratories.
     15  *
     16  * Redistribution and use in source and binary forms, with or without
     17  * modification, are permitted provided that the following conditions
     18  * are met:
     19  * 1. Redistributions of source code must retain the above copyright
     20  *    notice, this list of conditions and the following disclaimer.
     21  * 2. Redistributions in binary form must reproduce the above copyright
     22  *    notice, this list of conditions and the following disclaimer in the
     23  *    documentation and/or other materials provided with the distribution.
     24  * 3. Neither the name of the University nor the names of its contributors
     25  *    may be used to endorse or promote products derived from this software
     26  *    without specific prior written permission.
     27  *
     28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     38  * SUCH DAMAGE.
     39  *
     40  *	@(#)kgdb_glue.c	8.2 (Berkeley) 1/12/94
     41  */
     42 
     43 /*
     44  * This file must be compiled with gcc -fno-defer-pop.
     45  */
     46 
     47 #include <sys/cdefs.h>
     48 __KERNEL_RCSID(0, "$NetBSD: kgdb_glue.c,v 1.10 2007/10/17 19:58:04 garbled Exp $");
     49 
     50 #include "opt_kgdb.h"
     51 
     52 #ifdef KGDB
     53 
     54 #include <sys/param.h>
     55 
     56 #include <machine/frame.h>
     57 #include <machine/reg.h>
     58 
     59 #ifndef lint
     60 static char rcsid[] = "$NetBSD: kgdb_glue.c,v 1.10 2007/10/17 19:58:04 garbled Exp $";
     61 #endif
     62 
     63 #define KGDB_STACKSIZE 0x800
     64 #define KGDB_STACKWORDS (KGDB_STACKSIZE / sizeof(u_long))
     65 
     66 u_long kgdb_stack[KGDB_STACKWORDS];
     67 
     68 #define getsp(v) __asm("movl %%sp, %0" : "=r" (v))
     69 #define setsp(v) __asm("movl %0, %%sp" :: "r" (v))
     70 
     71 static inline void
     72 copywords(u_long *src, u_long *dst, u_int nbytes)
     73 {
     74 	u_long *limit = src + (nbytes / sizeof(u_long));
     75 
     76 	do {
     77 		*dst++ = *src++;
     78 	} while (src < limit);
     79 	if (nbytes & 2)
     80 		*(u_short *)dst = *(u_short *)src;
     81 }
     82 
     83 int
     84 kgdb_trap_glue(int type, struct frame frame)
     85 {
     86 	u_long osp, nsp;
     87 	u_int fsize, s;
     88 	extern short exframesize[];
     89 
     90 	/*
     91 	 * After a kernel mode trap, the saved sp doesn't point to the right
     92 	 * place.  The correct value is the top of the frame (i.e. before the
     93 	 * KGDB trap).
     94 	 *
     95 	 * XXX this may have to change if we implement an interrupt stack.
     96 	 */
     97 	fsize = sizeof(frame) - sizeof(frame.F_u) + exframesize[frame.f_format];
     98 	frame.f_regs[SP] = (u_long)&frame + fsize;
     99 
    100 	/*
    101 	 * Copy the interrupt context and frame to the new stack.
    102 	 * We're throwing away trap()'s frame since we're going to do
    103 	 * our own rte.
    104 	 */
    105 	nsp = (u_long)&kgdb_stack[KGDB_STACKWORDS] -
    106 	      roundup(fsize, sizeof(u_long));
    107 
    108 	copywords((u_long *)&frame, (u_long *)nsp, fsize);
    109 
    110 	s = splhigh();
    111 
    112 	getsp(osp);
    113 	setsp(nsp);
    114 
    115 	if (kgdb_trap(type, (struct frame *)nsp) == 0) {
    116 		/*
    117 		 * Get back on kernel stack.  This thread of control
    118 		 * will return back up through trap().  If kgdb_trap()
    119 		 * returns 0, it didn't handle the trap at all so
    120 		 * the stack is still intact and everything will
    121 		 * unwind okay from here up.
    122 		 */
    123 		setsp(osp);
    124 		splx(s);
    125 		return 0;
    126 	}
    127 	/*
    128 	 * Copy back context, which has possibly changed.  Even the
    129 	 * sp might have changed.
    130 	 */
    131 	osp = ((struct frame *)nsp)->f_regs[SP] - fsize;
    132 	copywords((u_long *)nsp, (u_long *)osp, fsize);
    133 	setsp(osp);
    134 
    135 	/*
    136 	 * Restore the possible new context from frame, pop the
    137 	 * unneeded usp (we trapped from kernel mode) and pad word,
    138 	 * and return to the trapped thread.
    139 	 */
    140 	__asm("moveml %sp@+,#0x7FFF; addql #8,sp; rte");
    141 }
    142 
    143 int kgdb_testval;
    144 
    145 int
    146 kgdb_test(int i)
    147 {
    148 	++kgdb_testval;
    149 	return (i + 1);
    150 }
    151 #endif /* KGDB */
    152