b3113cfdfe
attempt to IPI other cpus when entering the debugger in order to stop them while in the debugger. The default remains to issue the stop; however, that can result in a hang if another cpu has interrupts disabled and is spinning, since the IPI won't be received and the KDB will wait indefinitely. We probably need to add a timeout, but this is a useful stopgap in the mean time. Reviewed by: marcel
430 lines
9.0 KiB
C
430 lines
9.0 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 <sys/param.h>
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#include <sys/systm.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/smp.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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int kdb_active = 0;
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void *kdb_jmpbufp = NULL;
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struct kdb_dbbe *kdb_dbbe = NULL;
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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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KDB_BACKEND(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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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, 0, 0,
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kdb_sysctl_available, "A", "list of available KDB backends");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0,
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kdb_sysctl_current, "A", "currently selected KDB backend");
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SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
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kdb_sysctl_enter, "I", "set to enter the debugger");
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/*
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* Flag indicating whether or not to IPI the other CPUs to stop them on
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* entering the debugger. Sometimes, this will result in a deadlock as
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* stop_cpus() waits for the other cpus to stop, so we allow it to be
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* disabled.
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*/
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#ifdef SMP
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static int kdb_stop_cpus = 1;
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SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW,
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&kdb_stop_cpus, 0, "");
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#endif
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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 *be, **iter;
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char *avail, *p;
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ssize_t len, sz;
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int error;
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sz = 0;
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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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sz += strlen(be->dbbe_name) + 1;
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}
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sz++;
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avail = malloc(sz, M_TEMP, M_WAITOK);
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p = avail;
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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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len = snprintf(p, sz, "%s ", be->dbbe_name);
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p += len;
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sz -= len;
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}
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}
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KASSERT(sz >= 0, ("%s", __func__));
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error = sysctl_handle_string(oidp, avail, 0, req);
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free(avail, M_TEMP);
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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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strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
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buf[sizeof(buf) - 1] = '\0';
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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("sysctl debug.kdb.enter");
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return (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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int
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kdb_alt_break(int key, int *state)
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{
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int brk;
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brk = 0;
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switch (key) {
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case KEY_CR:
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*state = KEY_TILDE;
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break;
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case KEY_TILDE:
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*state = (*state == KEY_TILDE) ? KEY_CRTLB : 0;
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break;
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case KEY_CRTLB:
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if (*state == KEY_CRTLB)
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brk = 1;
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/* FALLTHROUGH */
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default:
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*state = 0;
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break;
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}
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return (brk);
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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()
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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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}
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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().
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*/
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void
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kdb_enter(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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breakpoint();
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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()
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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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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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return ((thr == curthread) ? &kdb_pcb : thr->td_pcb);
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}
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struct thread *
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kdb_thr_first(void)
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{
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struct proc *p;
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struct thread *thr;
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p = LIST_FIRST(&allproc);
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while (p != NULL) {
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if (p->p_sflag & PS_INMEM) {
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thr = FIRST_THREAD_IN_PROC(p);
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if (thr != NULL)
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return (thr);
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}
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p = LIST_NEXT(p, p_list);
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}
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return (NULL);
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}
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struct thread *
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kdb_thr_from_pid(pid_t pid)
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{
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struct proc *p;
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p = LIST_FIRST(&allproc);
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while (p != NULL) {
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if (p->p_sflag & PS_INMEM && p->p_pid == pid)
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return (FIRST_THREAD_IN_PROC(p));
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p = LIST_NEXT(p, p_list);
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}
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return (NULL);
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}
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struct thread *
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kdb_thr_lookup(lwpid_t tid)
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{
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struct thread *thr;
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thr = kdb_thr_first();
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while (thr != NULL && thr->td_tid != tid)
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thr = kdb_thr_next(thr);
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return (thr);
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}
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struct thread *
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kdb_thr_next(struct thread *thr)
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{
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struct proc *p;
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p = thr->td_proc;
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thr = TAILQ_NEXT(thr, td_plist);
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do {
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if (thr != NULL)
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return (thr);
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p = LIST_NEXT(p, p_list);
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if (p != NULL && (p->p_sflag & PS_INMEM))
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thr = FIRST_THREAD_IN_PROC(p);
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} while (p != NULL);
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return (NULL);
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}
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int
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kdb_thr_select(struct thread *thr)
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{
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if (thr == NULL)
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return (EINVAL);
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kdb_thread = thr;
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kdb_thrctx = kdb_thr_ctx(thr);
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return (0);
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}
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/*
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* Enter the debugger due to a trap.
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*/
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int
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kdb_trap(int type, int code, struct trapframe *tf)
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{
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#ifdef SMP
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int did_stop_cpus;
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#endif
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int handled;
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if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL)
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return (0);
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/* We reenter the debugger through kdb_reenter(). */
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if (kdb_active)
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return (0);
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makectx(tf, &kdb_pcb);
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critical_enter();
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kdb_active++;
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kdb_frame = tf;
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kdb_thr_select(curthread);
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#ifdef SMP
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if ((did_stop_cpus = kdb_stop_cpus) != 0)
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stop_cpus(PCPU_GET(other_cpus));
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#endif
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/* Let MD code do its thing first... */
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kdb_cpu_trap(type, code);
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handled = kdb_dbbe->dbbe_trap(type, code);
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#ifdef SMP
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if (did_stop_cpus)
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restart_cpus(stopped_cpus);
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#endif
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kdb_active--;
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critical_exit();
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return (handled);
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}
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