cbc174356c
in which multiple (presumably different) debugger backends can be configured and which provides basic services to those backends. Besides providing services to backends, it also serves as the single point of contact for any and all code that wants to make use of the debugger functions, such as entering the debugger or handling of the alternate break sequence. For this purpose, the frontend has been made non-optional. All debugger requests are forwarded or handed over to the current backend, if applicable. Selection of the current backend is done by the debug.kdb.current sysctl. A list of configured backends can be obtained with the debug.kdb.available sysctl. One can enter the debugger by writing to the debug.kdb.enter sysctl.
385 lines
8.1 KiB
C
385 lines
8.1 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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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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struct kdb_dbbe *be, **iter;
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int error;
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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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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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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, buf) == 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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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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* 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_lookup(pid_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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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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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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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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