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      1 /*	$NetBSD: x86.c,v 1.4 2018/08/12 16:00:41 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2009 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Andrew Doran.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #ifndef lint
     34 __RCSID("$NetBSD: x86.c,v 1.4 2018/08/12 16:00:41 christos Exp $");
     35 #endif /* not lint */
     36 
     37 #include <ddb/ddb.h>
     38 
     39 #include <kvm.h>
     40 #include <nlist.h>
     41 #include <err.h>
     42 #include <stdlib.h>
     43 
     44 #include <machine/frame.h>
     45 #include <machine/pcb.h>
     46 #include <x86/db_machdep.h>
     47 
     48 #include "extern.h"
     49 
     50 #ifdef VM_MIN_KERNEL_ADDRESS_DEFAULT
     51 vaddr_t vm_min_kernel_address = VM_MIN_KERNEL_ADDRESS_DEFAULT;
     52 #endif
     53 
     54 static struct nlist nl[] = {
     55 	{ .n_name = "_dumppcb" },
     56 #ifdef VM_MIN_KERNEL_ADDRESS_DEFAULT
     57 	{ .n_name = "vm_min_kernel_address" },
     58 #endif
     59 	{ .n_name = NULL },
     60 };
     61 
     62 struct pcb	pcb;
     63 
     64 void
     65 db_mach_init(kvm_t *kd)
     66 {
     67 
     68 	if (kvm_nlist(kd, nl) == -1) {
     69 		errx(EXIT_FAILURE, "kvm_nlist: %s", kvm_geterr(kd));
     70 	}
     71 	if ((size_t)kvm_read(kd, nl[0].n_value, &pcb, sizeof(pcb)) !=
     72 	    sizeof(pcb)) {
     73 		errx(EXIT_FAILURE, "cannot read dumppcb: %s", kvm_geterr(kd));
     74 	}
     75 #ifdef VM_MIN_KERNEL_ADDRESS_DEFAULT
     76 	if ((size_t)kvm_read(kd, nl[1].n_value, &vm_min_kernel_address,
     77 	    sizeof(vm_min_kernel_address)) != sizeof(vm_min_kernel_address)) {
     78 		errx(EXIT_FAILURE, "cannot read vm_min_kernel_address: %s",
     79 		    kvm_geterr(kd));
     80 	}
     81 #endif
     82         ddb_regs.tf_sp = pcb.pcb_sp;
     83         ddb_regs.tf_bp = pcb.pcb_bp;
     84         if (ddb_regs.tf_bp != 0 && ddb_regs.tf_sp != 0) {
     85         	printf("Backtrace from time of crash is available.\n");
     86 	}
     87 }
     88