subr_kdb.c

Version: - FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
    1 /*-
    2  * Copyright (c) 2004 The FreeBSD Project
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  *
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
   16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   18  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: src/sys/kern/subr_kdb.c,v 1.5.2.5 2005/10/02 10:20:04 rwatson Exp $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/systm.h>
   32 #include <sys/kdb.h>
   33 #include <sys/kernel.h>
   34 #include <sys/malloc.h>
   35 #include <sys/pcpu.h>
   36 #include <sys/proc.h>
   37 #include <sys/smp.h>
   38 #include <sys/sysctl.h>
   39 
   40 #include <machine/kdb.h>
   41 #include <machine/pcb.h>
   42 
   43 #ifdef KDB_STOP_NMI
   44 #include <machine/smp.h>
   45 #endif
   46 
   47 /* 
   48  * KDB_STOP_NMI requires SMP to pick up the right dependencies
   49  * (And isn't useful on UP anyway) 
   50  */
   51 #if defined(KDB_STOP_NMI) && !defined(SMP)
   52 #error "options KDB_STOP_NMI" requires "options SMP"
   53 #endif
   54 
   55 int kdb_active = 0;
   56 void *kdb_jmpbufp = NULL;
   57 struct kdb_dbbe *kdb_dbbe = NULL;
   58 struct pcb kdb_pcb;
   59 struct pcb *kdb_thrctx = NULL;
   60 struct thread *kdb_thread = NULL;
   61 struct trapframe *kdb_frame = NULL;
   62 
   63 KDB_BACKEND(null, NULL, NULL, NULL);
   64 SET_DECLARE(kdb_dbbe_set, struct kdb_dbbe);
   65 
   66 static int kdb_sysctl_available(SYSCTL_HANDLER_ARGS);
   67 static int kdb_sysctl_current(SYSCTL_HANDLER_ARGS);
   68 static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
   69 
   70 SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
   71 
   72 SYSCTL_PROC(_debug_kdb, OID_AUTO, available, CTLTYPE_STRING | CTLFLAG_RD, 0, 0,
   73     kdb_sysctl_available, "A", "list of available KDB backends");
   74 
   75 SYSCTL_PROC(_debug_kdb, OID_AUTO, current, CTLTYPE_STRING | CTLFLAG_RW, 0, 0,
   76     kdb_sysctl_current, "A", "currently selected KDB backend");
   77 
   78 SYSCTL_PROC(_debug_kdb, OID_AUTO, enter, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
   79     kdb_sysctl_enter, "I", "set to enter the debugger");
   80 
   81 /*
   82  * Flag indicating whether or not to IPI the other CPUs to stop them on
   83  * entering the debugger.  Sometimes, this will result in a deadlock as
   84  * stop_cpus() waits for the other cpus to stop, so we allow it to be
   85  * disabled.
   86  */
   87 #ifdef SMP
   88 static int kdb_stop_cpus = 1;
   89 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW,
   90     &kdb_stop_cpus, 0, "");
   91 TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus);
   92 
   93 #ifdef KDB_STOP_NMI
   94 /* 
   95  * Provide an alternate method of stopping other CPUs. If another CPU has
   96  * disabled interrupts the conventional STOP IPI will be blocked. This 
   97  * NMI-based stop should get through in that case.
   98  */
   99 static int kdb_stop_cpus_with_nmi = 1;
  100 SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus_with_nmi, CTLTYPE_INT | CTLFLAG_RW,
  101     &kdb_stop_cpus_with_nmi, 0, "");
  102 TUNABLE_INT("debug.kdb.stop_cpus_with_nmi", &kdb_stop_cpus_with_nmi);
  103 #endif /* KDB_STOP_NMI */
  104 
  105 #endif
  106 
  107 static int
  108 kdb_sysctl_available(SYSCTL_HANDLER_ARGS)
  109 {
  110         struct kdb_dbbe *be, **iter;
  111         char *avail, *p;
  112         ssize_t len, sz;
  113         int error;
  114 
  115         sz = 0;
  116         SET_FOREACH(iter, kdb_dbbe_set) {
  117                 be = *iter;
  118                 if (be->dbbe_active == 0)
  119                         sz += strlen(be->dbbe_name) + 1;
  120         }
  121         sz++;
  122         avail = malloc(sz, M_TEMP, M_WAITOK);
  123         p = avail;
  124         *p = '\0';
  125 
  126         SET_FOREACH(iter, kdb_dbbe_set) {
  127                 be = *iter;
  128                 if (be->dbbe_active == 0) {
  129                         len = snprintf(p, sz, "%s ", be->dbbe_name);
  130                         p += len;
  131                         sz -= len;
  132                 }
  133         }
  134         KASSERT(sz >= 0, ("%s", __func__));
  135         error = sysctl_handle_string(oidp, avail, 0, req);
  136         free(avail, M_TEMP);
  137         return (error);
  138 }
  139 
  140 static int
  141 kdb_sysctl_current(SYSCTL_HANDLER_ARGS)
  142 {
  143         char buf[16];
  144         int error;
  145 
  146         if (kdb_dbbe != NULL) {
  147                 strncpy(buf, kdb_dbbe->dbbe_name, sizeof(buf));
  148                 buf[sizeof(buf) - 1] = '\0';
  149         } else
  150                 *buf = '\0';
  151         error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
  152         if (error != 0 || req->newptr == NULL)
  153                 return (error);
  154         if (kdb_active)
  155                 return (EBUSY);
  156         return (kdb_dbbe_select(buf));
  157 }
  158 
  159 static int
  160 kdb_sysctl_enter(SYSCTL_HANDLER_ARGS)
  161 {
  162         int error, i;
  163 
  164         error = sysctl_wire_old_buffer(req, sizeof(int));
  165         if (error == 0) {
  166                 i = 0;
  167                 error = sysctl_handle_int(oidp, &i, 0, req);
  168         }
  169         if (error != 0 || req->newptr == NULL)
  170                 return (error);
  171         if (kdb_active)
  172                 return (EBUSY);
  173         kdb_enter("sysctl debug.kdb.enter");
  174         return (0);
  175 }
  176 
  177 /*
  178  * Solaris implements a new BREAK which is initiated by a character sequence
  179  * CR ~ ^b which is similar to a familiar pattern used on Sun servers by the
  180  * Remote Console.
  181  *
  182  * Note that this function may be called from almost anywhere, with interrupts
  183  * disabled and with unknown locks held, so it must not access data other than
  184  * its arguments.  Its up to the caller to ensure that the state variable is
  185  * consistent.
  186  */
  187 
  188 #define KEY_CR          13      /* CR '\r' */
  189 #define KEY_TILDE       126     /* ~ */
  190 #define KEY_CRTLB       2       /* ^B */
  191 
  192 int
  193 kdb_alt_break(int key, int *state)
  194 {
  195         int brk;
  196 
  197         brk = 0;
  198         switch (key) {
  199         case KEY_CR:
  200                 *state = KEY_TILDE;
  201                 break;
  202         case KEY_TILDE:
  203                 *state = (*state == KEY_TILDE) ? KEY_CRTLB : 0;
  204                 break;
  205         case KEY_CRTLB:
  206                 if (*state == KEY_CRTLB)
  207                         brk = 1;
  208                 /* FALLTHROUGH */
  209         default:
  210                 *state = 0;
  211                 break;
  212         }
  213         return (brk);
  214 }
  215 
  216 /*
  217  * Print a backtrace of the calling thread. The backtrace is generated by
  218  * the selected debugger, provided it supports backtraces. If no debugger
  219  * is selected or the current debugger does not support backtraces, this
  220  * function silently returns.
  221  */
  222 
  223 void
  224 kdb_backtrace()
  225 {
  226 
  227         if (kdb_dbbe != NULL && kdb_dbbe->dbbe_trace != NULL) {
  228                 printf("KDB: stack backtrace:\n");
  229                 kdb_dbbe->dbbe_trace();
  230         }
  231 }
  232 
  233 /*
  234  * Set/change the current backend.
  235  */
  236 
  237 int
  238 kdb_dbbe_select(const char *name)
  239 {
  240         struct kdb_dbbe *be, **iter;
  241 
  242         SET_FOREACH(iter, kdb_dbbe_set) {
  243                 be = *iter;
  244                 if (be->dbbe_active == 0 && strcmp(be->dbbe_name, name) == 0) {
  245                         kdb_dbbe = be;
  246                         return (0);
  247                 }
  248         }
  249         return (EINVAL);
  250 }
  251 
  252 /*
  253  * Enter the currently selected debugger. If a message has been provided,
  254  * it is printed first. If the debugger does not support the enter method,
  255  * it is entered by using breakpoint(), which enters the debugger through
  256  * kdb_trap().
  257  */
  258 
  259 void
  260 kdb_enter(const char *msg)
  261 {
  262 
  263         if (kdb_dbbe != NULL && kdb_active == 0) {
  264                 if (msg != NULL)
  265                         printf("KDB: enter: %s\n", msg);
  266                 breakpoint();
  267         }
  268 }
  269 
  270 /*
  271  * Initialize the kernel debugger interface.
  272  */
  273 
  274 void
  275 kdb_init()
  276 {
  277         struct kdb_dbbe *be, **iter;
  278         int cur_pri, pri;
  279 
  280         kdb_active = 0;
  281         kdb_dbbe = NULL;
  282         cur_pri = -1;
  283         SET_FOREACH(iter, kdb_dbbe_set) {
  284                 be = *iter;
  285                 pri = (be->dbbe_init != NULL) ? be->dbbe_init() : -1;
  286                 be->dbbe_active = (pri >= 0) ? 0 : -1;
  287                 if (pri > cur_pri) {
  288                         cur_pri = pri;
  289                         kdb_dbbe = be;
  290                 }
  291         }
  292         if (kdb_dbbe != NULL) {
  293                 printf("KDB: debugger backends:");
  294                 SET_FOREACH(iter, kdb_dbbe_set) {
  295                         be = *iter;
  296                         if (be->dbbe_active == 0)
  297                                 printf(" %s", be->dbbe_name);
  298                 }
  299                 printf("\n");
  300                 printf("KDB: current backend: %s\n",
  301                     kdb_dbbe->dbbe_name);
  302         }
  303 }
  304 
  305 /*
  306  * Handle contexts.
  307  */
  308 
  309 void *
  310 kdb_jmpbuf(jmp_buf new)
  311 {
  312         void *old;
  313 
  314         old = kdb_jmpbufp;
  315         kdb_jmpbufp = new;
  316         return (old);
  317 }
  318 
  319 void
  320 kdb_reenter(void)
  321 {
  322 
  323         if (!kdb_active || kdb_jmpbufp == NULL)
  324                 return;
  325 
  326         longjmp(kdb_jmpbufp, 1);
  327         /* NOTREACHED */
  328 }
  329 
  330 /*
  331  * Thread related support functions.
  332  */
  333 
  334 struct pcb *
  335 kdb_thr_ctx(struct thread *thr)
  336 #ifdef KDB_STOP_NMI
  337 {  
  338   u_int         cpuid;
  339   struct pcpu *pc;
  340   
  341   if (thr == curthread) 
  342     return &kdb_pcb;
  343 
  344   SLIST_FOREACH(pc, &cpuhead, pc_allcpu)  {
  345     cpuid = pc->pc_cpuid;
  346     if (pc->pc_curthread == thr && (atomic_load_acq_int(&stopped_cpus) & (1 << cpuid)))
  347       return &stoppcbs[cpuid];
  348   }
  349 
  350   return  thr->td_pcb;
  351 }
  352 #else
  353 {
  354         return ((thr == curthread) ? &kdb_pcb : thr->td_pcb);
  355 }
  356 #endif /* KDB_STOP_NMI */
  357 
  358 struct thread *
  359 kdb_thr_first(void)
  360 {
  361         struct proc *p;
  362         struct thread *thr;
  363 
  364         p = LIST_FIRST(&allproc);
  365         while (p != NULL) {
  366                 if (p->p_sflag & PS_INMEM) {
  367                         thr = FIRST_THREAD_IN_PROC(p);
  368                         if (thr != NULL)
  369                                 return (thr);
  370                 }
  371                 p = LIST_NEXT(p, p_list);
  372         }
  373         return (NULL);
  374 }
  375 
  376 struct thread *
  377 kdb_thr_from_pid(pid_t pid)
  378 {
  379         struct proc *p;
  380 
  381         p = LIST_FIRST(&allproc);
  382         while (p != NULL) {
  383                 if (p->p_sflag & PS_INMEM && p->p_pid == pid)
  384                         return (FIRST_THREAD_IN_PROC(p));
  385                 p = LIST_NEXT(p, p_list);
  386         }
  387         return (NULL);
  388 }
  389 
  390 struct thread *
  391 kdb_thr_lookup(lwpid_t tid)
  392 {
  393         struct thread *thr;
  394 
  395         thr = kdb_thr_first();
  396         while (thr != NULL && thr->td_tid != tid)
  397                 thr = kdb_thr_next(thr);
  398         return (thr);
  399 }
  400 
  401 struct thread *
  402 kdb_thr_next(struct thread *thr)
  403 {
  404         struct proc *p;
  405 
  406         p = thr->td_proc;
  407         thr = TAILQ_NEXT(thr, td_plist);
  408         do {
  409                 if (thr != NULL)
  410                         return (thr);
  411                 p = LIST_NEXT(p, p_list);
  412                 if (p != NULL && (p->p_sflag & PS_INMEM))
  413                         thr = FIRST_THREAD_IN_PROC(p);
  414         } while (p != NULL);
  415         return (NULL);
  416 }
  417 
  418 int
  419 kdb_thr_select(struct thread *thr)
  420 {
  421         if (thr == NULL)
  422                 return (EINVAL);
  423         kdb_thread = thr;
  424         kdb_thrctx = kdb_thr_ctx(thr);
  425         return (0);
  426 }
  427 
  428 /*
  429  * Enter the debugger due to a trap.
  430  */
  431 
  432 int
  433 kdb_trap(int type, int code, struct trapframe *tf)
  434 {
  435 #ifdef SMP
  436         int did_stop_cpus;
  437 #endif
  438         int handled;
  439 
  440         if (kdb_dbbe == NULL || kdb_dbbe->dbbe_trap == NULL)
  441                 return (0);
  442 
  443         /* We reenter the debugger through kdb_reenter(). */
  444         if (kdb_active)
  445                 return (0);
  446 
  447         makectx(tf, &kdb_pcb);
  448 
  449         critical_enter();
  450 
  451         kdb_active++;
  452         kdb_frame = tf;
  453         kdb_thr_select(curthread);
  454 
  455 #ifdef SMP
  456         if ((did_stop_cpus = kdb_stop_cpus) != 0)
  457           {
  458 #ifdef KDB_STOP_NMI
  459             if(kdb_stop_cpus_with_nmi)
  460               stop_cpus_nmi(PCPU_GET(other_cpus));
  461             else
  462 #endif /* KDB_STOP_NMI */
  463                 stop_cpus(PCPU_GET(other_cpus));
  464           }
  465 #endif
  466 
  467         /* Let MD code do its thing first... */
  468         kdb_cpu_trap(type, code);
  469 
  470         handled = kdb_dbbe->dbbe_trap(type, code);
  471 
  472 #ifdef SMP
  473         if (did_stop_cpus)
  474                 restart_cpus(stopped_cpus);
  475 #endif
  476 
  477         kdb_active--;
  478 
  479         critical_exit();
  480 
  481         return (handled);
  482 }
Cache object: c9c9dce12cd94ce8bd0a384f854ae509
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.
FreeBSD/Linux Kernel Cross Reference sys/kern/subr_kdb.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_kdb.c
