676 lines
14 KiB
C
676 lines
14 KiB
C
/*-
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* Copyright (c) 2004 The FreeBSD Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kdb.h"
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#include "opt_stack.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/cons.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/malloc.h>
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#include <sys/pcpu.h>
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#include <sys/proc.h>
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#include <sys/sbuf.h>
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#include <sys/smp.h>
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#include <sys/stack.h>
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#include <sys/sysctl.h>
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#include <machine/kdb.h>
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#include <machine/pcb.h>
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#ifdef SMP
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#include <machine/smp.h>
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#endif
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int kdb_active = 0;
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static void *kdb_jmpbufp = NULL;
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struct kdb_dbbe *kdb_dbbe = NULL;
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static struct pcb kdb_pcb;
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struct pcb *kdb_thrctx = NULL;
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struct thread *kdb_thread = NULL;
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struct trapframe *kdb_frame = NULL;
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#ifdef BREAK_TO_DEBUGGER
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#define KDB_BREAK_TO_DEBUGGER 1
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#else
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#define KDB_BREAK_TO_DEBUGGER 0
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#endif
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#ifdef ALT_BREAK_TO_DEBUGGER
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#define KDB_ALT_BREAK_TO_DEBUGGER 1
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#else
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#define KDB_ALT_BREAK_TO_DEBUGGER 0
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#endif
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static int kdb_break_to_debugger = KDB_BREAK_TO_DEBUGGER;
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static int kdb_alt_break_to_debugger = KDB_ALT_BREAK_TO_DEBUGGER;
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KDB_BACKEND(null, NULL, NULL, NULL, NULL);
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SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
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static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
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static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
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static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
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static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
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static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
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static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
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static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, NULL,
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0, kdb_sysctl_available, "A", "list of available KDB backends");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, NULL,
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0, kdb_sysctl_current, "A", "currently selected KDB backend");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, enter,
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CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
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kdb_sysctl_enter, "I", "set to enter the debugger");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, panic,
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CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
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kdb_sysctl_panic, "I", "set to panic the kernel");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, trap,
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CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
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kdb_sysctl_trap, "I", "set to cause a page fault via data access");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
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CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
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kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
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SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
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CTLFLAG_RWTUN | CTLFLAG_SECURE,
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&kdb_break_to_debugger, 0, "Enable break to debugger");
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SYSCTL_INT(_debug_kdb, OID_AUTO, alt_break_to_debugger,
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CTLFLAG_RWTUN | CTLFLAG_SECURE,
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&kdb_alt_break_to_debugger, 0, "Enable alternative break to debugger");
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/*
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* Flag to indicate to debuggers why the debugger was entered.
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*/
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const char * volatile kdb_why = KDB_WHY_UNSET;
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static int
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kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
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{
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struct kdb_dbbe **iter;
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struct sbuf sbuf;
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int error;
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sbuf_new_for_sysctl(&sbuf, NULL, 64, req);
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SET_FOREACH(iter, kdb_dbbe_set) {
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if ((*iter)->dbbe_active == 0)
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sbuf_printf(&sbuf, "%s ", (*iter)->dbbe_name);
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}
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error = sbuf_finish(&sbuf);
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sbuf_delete(&sbuf);
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return (error);
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}
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static int
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kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
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{
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char buf[16];
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int error;
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if (kdb_dbbe != NULL)
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strlcpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
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else
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*buf = '\0';
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error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (kdb_active)
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return (EBUSY);
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return (kdb_dbbe_select(buf));
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}
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static int
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kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
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{
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int error, i;
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error = sysctl_wire_old_buffer(req, sizeof(int));
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if (error == 0) {
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i = 0;
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error = sysctl_handle_int(oidp, &i, 0, req);
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}
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (kdb_active)
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return (EBUSY);
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kdb_enter(KDB_WHY_SYSCTL, "sysctl debug.kdb.enter");
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return (0);
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}
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static int
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kdb_sysctl_panic(SYSCTL_HANDLER_ARGS)
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{
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int error, i;
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error = sysctl_wire_old_buffer(req, sizeof(int));
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if (error == 0) {
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i = 0;
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error = sysctl_handle_int(oidp, &i, 0, req);
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}
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if (error != 0 || req->newptr == NULL)
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return (error);
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panic("kdb_sysctl_panic");
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return (0);
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}
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static int
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kdb_sysctl_trap(SYSCTL_HANDLER_ARGS)
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{
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int error, i;
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int *addr = (int *)0x10;
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error = sysctl_wire_old_buffer(req, sizeof(int));
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if (error == 0) {
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i = 0;
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error = sysctl_handle_int(oidp, &i, 0, req);
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}
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if (error != 0 || req->newptr == NULL)
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return (error);
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return (*addr);
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}
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static int
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kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
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{
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int error, i;
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void (*fp)(u_int, u_int, u_int) = (void *)0xdeadc0de;
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error = sysctl_wire_old_buffer(req, sizeof(int));
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if (error == 0) {
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i = 0;
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error = sysctl_handle_int(oidp, &i, 0, req);
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}
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if (error != 0 || req->newptr == NULL)
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return (error);
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(*fp)(0x11111111, 0x22222222, 0x33333333);
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return (0);
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}
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void
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kdb_panic(const char *msg)
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{
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printf("KDB: panic\n");
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panic("%s", msg);
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}
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void
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kdb_reboot(void)
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{
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printf("KDB: reboot requested\n");
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shutdown_nice(0);
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}
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/*
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* Solaris implements a new BREAK which is initiated by a character sequence
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* CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
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* Remote Console.
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*
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* Note that this function may be called from almost anywhere, with interrupts
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* disabled and with unknown locks held, so it must not access data other than
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* its arguments. Its up to the caller to ensure that the state variable is
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* consistent.
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*/
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#define KEY_CR 13 /* CR '\r' */
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#define KEY_TILDE 126 /* ~ */
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#define KEY_CRTLB 2 /* ^B */
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#define KEY_CRTLP 16 /* ^P */
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#define KEY_CRTLR 18 /* ^R */
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/* States of th KDB "alternate break sequence" detecting state machine. */
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enum {
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KDB_ALT_BREAK_SEEN_NONE,
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KDB_ALT_BREAK_SEEN_CR,
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KDB_ALT_BREAK_SEEN_CR_TILDE,
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};
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int
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kdb_break(void)
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{
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if (!kdb_break_to_debugger)
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return (0);
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kdb_enter(KDB_WHY_BREAK, "Break to debugger");
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return (KDB_REQ_DEBUGGER);
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}
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static int
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kdb_alt_break_state(int key, int *state)
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{
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int brk;
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/* All states transition to KDB_ALT_BREAK_SEEN_CR on a CR. */
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if (key == KEY_CR) {
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*state = KDB_ALT_BREAK_SEEN_CR;
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return (0);
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}
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brk = 0;
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switch (*state) {
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case KDB_ALT_BREAK_SEEN_CR:
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*state = KDB_ALT_BREAK_SEEN_NONE;
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if (key == KEY_TILDE)
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*state = KDB_ALT_BREAK_SEEN_CR_TILDE;
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break;
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case KDB_ALT_BREAK_SEEN_CR_TILDE:
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*state = KDB_ALT_BREAK_SEEN_NONE;
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if (key == KEY_CRTLB)
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brk = KDB_REQ_DEBUGGER;
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else if (key == KEY_CRTLP)
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brk = KDB_REQ_PANIC;
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else if (key == KEY_CRTLR)
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brk = KDB_REQ_REBOOT;
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break;
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case KDB_ALT_BREAK_SEEN_NONE:
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default:
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*state = KDB_ALT_BREAK_SEEN_NONE;
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break;
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}
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return (brk);
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}
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static int
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kdb_alt_break_internal(int key, int *state, int force_gdb)
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{
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int brk;
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if (!kdb_alt_break_to_debugger)
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return (0);
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brk = kdb_alt_break_state(key, state);
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switch (brk) {
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case KDB_REQ_DEBUGGER:
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if (force_gdb)
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kdb_dbbe_select("gdb");
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kdb_enter(KDB_WHY_BREAK, "Break to debugger");
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break;
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case KDB_REQ_PANIC:
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if (force_gdb)
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kdb_dbbe_select("gdb");
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kdb_panic("Panic sequence on console");
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break;
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case KDB_REQ_REBOOT:
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kdb_reboot();
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break;
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}
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return (0);
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}
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int
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kdb_alt_break(int key, int *state)
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{
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return (kdb_alt_break_internal(key, state, 0));
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}
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/*
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* This variation on kdb_alt_break() is used only by dcons, which has its own
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* configuration flag to force GDB use regardless of the global KDB
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* configuration.
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*/
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int
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kdb_alt_break_gdb(int key, int *state)
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{
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return (kdb_alt_break_internal(key, state, 1));
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}
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/*
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* Print a backtrace of the calling thread. The backtrace is generated by
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* the selected debugger, provided it supports backtraces. If no debugger
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* is selected or the current debugger does not support backtraces, this
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* function silently returns.
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*/
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void
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kdb_backtrace(void)
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{
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if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
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printf("KDB: stack backtrace:\n");
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kdb_dbbe->dbbe_trace();
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}
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#ifdef STACK
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else {
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struct stack st;
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printf("KDB: stack backtrace:\n");
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stack_zero(&st);
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stack_save(&st);
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stack_print_ddb(&st);
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}
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#endif
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}
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/*
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* Similar to kdb_backtrace() except that it prints a backtrace of an
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* arbitrary thread rather than the calling thread.
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*/
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void
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kdb_backtrace_thread(struct thread *td)
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{
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if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace_thread != NULL) {
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printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
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kdb_dbbe->dbbe_trace_thread(td);
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}
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#ifdef STACK
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else {
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struct stack st;
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printf("KDB: stack backtrace of thread %d:\n", td->td_tid);
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stack_zero(&st);
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stack_save_td(&st, td);
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stack_print_ddb(&st);
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}
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#endif
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}
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/*
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* Set/change the current backend.
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*/
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int
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kdb_dbbe_select(const char *name)
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{
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struct kdb_dbbe *be, **iter;
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SET_FOREACH(iter, kdb_dbbe_set) {
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be = *iter;
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if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
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kdb_dbbe = be;
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return (0);
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}
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}
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return (EINVAL);
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}
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/*
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* Enter the currently selected debugger. If a message has been provided,
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* it is printed first. If the debugger does not support the enter method,
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* it is entered by using breakpoint(), which enters the debugger through
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* kdb_trap(). The 'why' argument will contain a more mechanically usable
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* string than 'msg', and is relied upon by DDB scripting to identify the
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* reason for entering the debugger so that the right script can be run.
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*/
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void
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kdb_enter(const char *why, const char *msg)
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{
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if (kdb_dbbe != NULL && kdb_active == 0) {
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if (msg != NULL)
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printf("KDB: enter: %s\n", msg);
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kdb_why = why;
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breakpoint();
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kdb_why = KDB_WHY_UNSET;
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}
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}
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/*
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* Initialize the kernel debugger interface.
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*/
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void
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kdb_init(void)
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{
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struct kdb_dbbe *be, **iter;
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int cur_pri, pri;
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kdb_active = 0;
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kdb_dbbe = NULL;
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cur_pri = -1;
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SET_FOREACH(iter, kdb_dbbe_set) {
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be = *iter;
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pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
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be->dbbe_active = (pri >= 0) ? 0 : -1;
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if (pri > cur_pri) {
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cur_pri = pri;
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kdb_dbbe = be;
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}
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}
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if (kdb_dbbe != NULL) {
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printf("KDB: debugger backends:");
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SET_FOREACH(iter, kdb_dbbe_set) {
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be = *iter;
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if (be->dbbe_active == 0)
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printf(" %s", be->dbbe_name);
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}
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printf("\n");
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printf("KDB: current backend: %s\n",
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kdb_dbbe->dbbe_name);
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}
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}
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/*
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* Handle contexts.
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*/
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void *
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kdb_jmpbuf(jmp_buf new)
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{
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void *old;
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old = kdb_jmpbufp;
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kdb_jmpbufp = new;
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return (old);
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}
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void
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kdb_reenter(void)
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{
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if (!kdb_active || kdb_jmpbufp == NULL)
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return;
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printf("KDB: reentering\n");
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kdb_backtrace();
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longjmp(kdb_jmpbufp, 1);
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/* NOTREACHED */
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}
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/*
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* Thread related support functions.
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*/
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struct pcb *
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kdb_thr_ctx(struct thread *thr)
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{
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#if defined(SMP) && defined(KDB_STOPPEDPCB)
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struct pcpu *pc;
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#endif
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if (thr == curthread)
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return (&kdb_pcb);
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#if defined(SMP) && defined(KDB_STOPPEDPCB)
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STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
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if (pc->pc_curthread == thr &&
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CPU_ISSET(pc->pc_cpuid, &stopped_cpus))
|
|
return (KDB_STOPPEDPCB(pc));
|
|
}
|
|
#endif
|
|
return (thr->td_pcb);
|
|
}
|
|
|
|
struct thread *
|
|
kdb_thr_first(void)
|
|
{
|
|
struct proc *p;
|
|
struct thread *thr;
|
|
|
|
p = LIST_FIRST(&allproc);
|
|
while (p != NULL) {
|
|
if (p->p_flag & P_INMEM) {
|
|
thr = FIRST_THREAD_IN_PROC(p);
|
|
if (thr != NULL)
|
|
return (thr);
|
|
}
|
|
p = LIST_NEXT(p, p_list);
|
|
}
|
|
return (NULL);
|
|
}
|
|
|
|
struct thread *
|
|
kdb_thr_from_pid(pid_t pid)
|
|
{
|
|
struct proc *p;
|
|
|
|
p = LIST_FIRST(&allproc);
|
|
while (p != NULL) {
|
|
if (p->p_flag & P_INMEM && p->p_pid == pid)
|
|
return (FIRST_THREAD_IN_PROC(p));
|
|
p = LIST_NEXT(p, p_list);
|
|
}
|
|
return (NULL);
|
|
}
|
|
|
|
struct thread *
|
|
kdb_thr_lookup(lwpid_t tid)
|
|
{
|
|
struct thread *thr;
|
|
|
|
thr = kdb_thr_first();
|
|
while (thr != NULL && thr->td_tid != tid)
|
|
thr = kdb_thr_next(thr);
|
|
return (thr);
|
|
}
|
|
|
|
struct thread *
|
|
kdb_thr_next(struct thread *thr)
|
|
{
|
|
struct proc *p;
|
|
|
|
p = thr->td_proc;
|
|
thr = TAILQ_NEXT(thr, td_plist);
|
|
do {
|
|
if (thr != NULL)
|
|
return (thr);
|
|
p = LIST_NEXT(p, p_list);
|
|
if (p != NULL && (p->p_flag & P_INMEM))
|
|
thr = FIRST_THREAD_IN_PROC(p);
|
|
} while (p != NULL);
|
|
return (NULL);
|
|
}
|
|
|
|
int
|
|
kdb_thr_select(struct thread *thr)
|
|
{
|
|
if (thr == NULL)
|
|
return (EINVAL);
|
|
kdb_thread = thr;
|
|
kdb_thrctx = kdb_thr_ctx(thr);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Enter the debugger due to a trap.
|
|
*/
|
|
|
|
int
|
|
kdb_trap(int type, int code, struct trapframe *tf)
|
|
{
|
|
#ifdef SMP
|
|
cpuset_t other_cpus;
|
|
#endif
|
|
struct kdb_dbbe *be;
|
|
register_t intr;
|
|
int handled;
|
|
#ifdef SMP
|
|
int did_stop_cpus;
|
|
#endif
|
|
|
|
be = kdb_dbbe;
|
|
if (be == NULL || be->dbbe_trap == NULL)
|
|
return (0);
|
|
|
|
/* We reenter the debugger through kdb_reenter(). */
|
|
if (kdb_active)
|
|
return (0);
|
|
|
|
intr = intr_disable();
|
|
|
|
#ifdef SMP
|
|
if (!SCHEDULER_STOPPED()) {
|
|
other_cpus = all_cpus;
|
|
CPU_CLR(PCPU_GET(cpuid), &other_cpus);
|
|
stop_cpus_hard(other_cpus);
|
|
did_stop_cpus = 1;
|
|
} else
|
|
did_stop_cpus = 0;
|
|
#endif
|
|
|
|
kdb_active++;
|
|
|
|
kdb_frame = tf;
|
|
|
|
/* Let MD code do its thing first... */
|
|
kdb_cpu_trap(type, code);
|
|
|
|
makectx(tf, &kdb_pcb);
|
|
kdb_thr_select(curthread);
|
|
|
|
cngrab();
|
|
|
|
for (;;) {
|
|
handled = be->dbbe_trap(type, code);
|
|
if (be == kdb_dbbe)
|
|
break;
|
|
be = kdb_dbbe;
|
|
if (be == NULL || be->dbbe_trap == NULL)
|
|
break;
|
|
printf("Switching to %s back-end\n", be->dbbe_name);
|
|
}
|
|
|
|
cnungrab();
|
|
|
|
kdb_active--;
|
|
|
|
#ifdef SMP
|
|
if (did_stop_cpus)
|
|
restart_cpus(stopped_cpus);
|
|
#endif
|
|
|
|
intr_restore(intr);
|
|
|
|
return (handled);
|
|
}
|