The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_break.c

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    1 /*-
    2  * SPDX-License-Identifier: MIT-CMU
    3  *
    4  * Mach Operating System
    5  * Copyright (c) 1991,1990 Carnegie Mellon University
    6  * All Rights Reserved.
    7  *
    8  * Permission to use, copy, modify and distribute this software and its
    9  * documentation is hereby granted, provided that both the copyright
   10  * notice and this permission notice appear in all copies of the
   11  * software, derivative works or modified versions, and any portions
   12  * thereof, and that both notices appear in supporting documentation.
   13  *
   14  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
   15  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   16  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   17  *
   18  * Carnegie Mellon requests users of this software to return to
   19  *
   20  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   21  *  School of Computer Science
   22  *  Carnegie Mellon University
   23  *  Pittsburgh PA 15213-3890
   24  *
   25  * any improvements or extensions that they make and grant Carnegie the
   26  * rights to redistribute these changes.
   27  *
   28  */
   29 /*
   30  *      Author: David B. Golub, Carnegie Mellon University
   31  *      Date:   7/90
   32  */
   33 /*
   34  * Breakpoints.
   35  */
   36 
   37 #include <sys/cdefs.h>
   38 __FBSDID("$FreeBSD$");
   39 
   40 #include <sys/param.h>
   41 
   42 #include <vm/vm.h>
   43 #include <vm/vm_kern.h>
   44 
   45 #include <ddb/ddb.h>
   46 #include <ddb/db_break.h>
   47 #include <ddb/db_access.h>
   48 #include <ddb/db_sym.h>
   49 
   50 #define NBREAKPOINTS    100
   51 static struct db_breakpoint     db_break_table[NBREAKPOINTS];
   52 static db_breakpoint_t          db_next_free_breakpoint = &db_break_table[0];
   53 static db_breakpoint_t          db_free_breakpoints = 0;
   54 static db_breakpoint_t          db_breakpoint_list = 0;
   55 
   56 static db_breakpoint_t  db_breakpoint_alloc(void);
   57 static void     db_breakpoint_free(db_breakpoint_t bkpt);
   58 static void     db_delete_breakpoint(vm_map_t map, db_addr_t addr);
   59 static db_breakpoint_t  db_find_breakpoint(vm_map_t map, db_addr_t addr);
   60 static void     db_list_breakpoints(void);
   61 static void     db_set_breakpoint(vm_map_t map, db_addr_t addr, int count);
   62 
   63 static db_breakpoint_t
   64 db_breakpoint_alloc(void)
   65 {
   66         register db_breakpoint_t        bkpt;
   67 
   68         if ((bkpt = db_free_breakpoints) != 0) {
   69             db_free_breakpoints = bkpt->link;
   70             return (bkpt);
   71         }
   72         if (db_next_free_breakpoint == &db_break_table[NBREAKPOINTS]) {
   73             db_printf("All breakpoints used.\n");
   74             return (0);
   75         }
   76         bkpt = db_next_free_breakpoint;
   77         db_next_free_breakpoint++;
   78 
   79         return (bkpt);
   80 }
   81 
   82 static void
   83 db_breakpoint_free(db_breakpoint_t bkpt)
   84 {
   85         bkpt->link = db_free_breakpoints;
   86         db_free_breakpoints = bkpt;
   87 }
   88 
   89 static void
   90 db_set_breakpoint(vm_map_t map, db_addr_t addr, int count)
   91 {
   92         register db_breakpoint_t        bkpt;
   93 
   94         if (db_find_breakpoint(map, addr)) {
   95             db_printf("Already set.\n");
   96             return;
   97         }
   98 
   99         bkpt = db_breakpoint_alloc();
  100         if (bkpt == 0) {
  101             db_printf("Too many breakpoints.\n");
  102             return;
  103         }
  104 
  105         bkpt->map = map;
  106         bkpt->address = addr;
  107         bkpt->flags = 0;
  108         bkpt->init_count = count;
  109         bkpt->count = count;
  110 
  111         bkpt->link = db_breakpoint_list;
  112         db_breakpoint_list = bkpt;
  113 }
  114 
  115 static void
  116 db_delete_breakpoint(vm_map_t map, db_addr_t addr)
  117 {
  118         register db_breakpoint_t        bkpt;
  119         register db_breakpoint_t        *prev;
  120 
  121         for (prev = &db_breakpoint_list;
  122              (bkpt = *prev) != 0;
  123              prev = &bkpt->link) {
  124             if (db_map_equal(bkpt->map, map) &&
  125                 (bkpt->address == addr)) {
  126                 *prev = bkpt->link;
  127                 break;
  128             }
  129         }
  130         if (bkpt == 0) {
  131             db_printf("Not set.\n");
  132             return;
  133         }
  134 
  135         db_breakpoint_free(bkpt);
  136 }
  137 
  138 static db_breakpoint_t
  139 db_find_breakpoint(vm_map_t map, db_addr_t addr)
  140 {
  141         register db_breakpoint_t        bkpt;
  142 
  143         for (bkpt = db_breakpoint_list;
  144              bkpt != 0;
  145              bkpt = bkpt->link)
  146         {
  147             if (db_map_equal(bkpt->map, map) &&
  148                 (bkpt->address == addr))
  149                 return (bkpt);
  150         }
  151         return (0);
  152 }
  153 
  154 db_breakpoint_t
  155 db_find_breakpoint_here(db_addr_t addr)
  156 {
  157         return db_find_breakpoint(db_map_addr(addr), addr);
  158 }
  159 
  160 static bool     db_breakpoints_inserted = true;
  161 
  162 #ifndef BKPT_WRITE
  163 #define BKPT_WRITE(addr, storage)                               \
  164 do {                                                            \
  165         *storage = db_get_value(addr, BKPT_SIZE, false);        \
  166         db_put_value(addr, BKPT_SIZE, BKPT_SET(*storage));      \
  167 } while (0)
  168 #endif
  169 
  170 #ifndef BKPT_CLEAR
  171 #define BKPT_CLEAR(addr, storage) \
  172         db_put_value(addr, BKPT_SIZE, *storage)
  173 #endif
  174 
  175 void
  176 db_set_breakpoints(void)
  177 {
  178         register db_breakpoint_t        bkpt;
  179 
  180         if (!db_breakpoints_inserted) {
  181 
  182                 for (bkpt = db_breakpoint_list;
  183                      bkpt != 0;
  184                      bkpt = bkpt->link)
  185                         if (db_map_current(bkpt->map)) {
  186                                 BKPT_WRITE(bkpt->address, &bkpt->bkpt_inst);
  187                         }
  188                 db_breakpoints_inserted = true;
  189         }
  190 }
  191 
  192 void
  193 db_clear_breakpoints(void)
  194 {
  195         register db_breakpoint_t        bkpt;
  196 
  197         if (db_breakpoints_inserted) {
  198 
  199                 for (bkpt = db_breakpoint_list;
  200                      bkpt != 0;
  201                      bkpt = bkpt->link)
  202                         if (db_map_current(bkpt->map)) {
  203                                 BKPT_CLEAR(bkpt->address, &bkpt->bkpt_inst);
  204                         }
  205                 db_breakpoints_inserted = false;
  206         }
  207 }
  208 
  209 #ifdef SOFTWARE_SSTEP
  210 /*
  211  * Set a temporary breakpoint.
  212  * The instruction is changed immediately,
  213  * so the breakpoint does not have to be on the breakpoint list.
  214  */
  215 db_breakpoint_t
  216 db_set_temp_breakpoint(db_addr_t addr)
  217 {
  218         register db_breakpoint_t        bkpt;
  219 
  220         bkpt = db_breakpoint_alloc();
  221         if (bkpt == 0) {
  222             db_printf("Too many breakpoints.\n");
  223             return 0;
  224         }
  225 
  226         bkpt->map = NULL;
  227         bkpt->address = addr;
  228         bkpt->flags = BKPT_TEMP;
  229         bkpt->init_count = 1;
  230         bkpt->count = 1;
  231 
  232         BKPT_WRITE(bkpt->address, &bkpt->bkpt_inst);
  233         return bkpt;
  234 }
  235 
  236 void
  237 db_delete_temp_breakpoint(db_breakpoint_t bkpt)
  238 {
  239         BKPT_CLEAR(bkpt->address, &bkpt->bkpt_inst);
  240         db_breakpoint_free(bkpt);
  241 }
  242 #endif /* SOFTWARE_SSTEP */
  243 
  244 /*
  245  * List breakpoints.
  246  */
  247 static void
  248 db_list_breakpoints(void)
  249 {
  250         register db_breakpoint_t        bkpt;
  251 
  252         if (db_breakpoint_list == 0) {
  253             db_printf("No breakpoints set\n");
  254             return;
  255         }
  256 
  257         db_printf(" Map      Count    Address\n");
  258         for (bkpt = db_breakpoint_list;
  259              bkpt != 0;
  260              bkpt = bkpt->link) {
  261             db_printf("%s%8p %5d    ",
  262                       db_map_current(bkpt->map) ? "*" : " ",
  263                       (void *)bkpt->map, bkpt->init_count);
  264             db_printsym(bkpt->address, DB_STGY_PROC);
  265             db_printf("\n");
  266         }
  267 }
  268 
  269 /* Delete breakpoint */
  270 /*ARGSUSED*/
  271 void
  272 db_delete_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
  273 {
  274         db_delete_breakpoint(db_map_addr(addr), (db_addr_t)addr);
  275 }
  276 
  277 /* Set breakpoint with skip count */
  278 /*ARGSUSED*/
  279 void
  280 db_breakpoint_cmd(db_expr_t addr, bool have_addr, db_expr_t count, char *modif)
  281 {
  282         if (count == -1)
  283             count = 1;
  284 
  285         db_set_breakpoint(db_map_addr(addr), (db_addr_t)addr, count);
  286 }
  287 
  288 /* list breakpoints */
  289 void
  290 db_listbreak_cmd(db_expr_t dummy1, bool dummy2, db_expr_t dummy3, char *dummy4)
  291 {
  292         db_list_breakpoints();
  293 }
  294 
  295 /*
  296  *      We want ddb to be usable before most of the kernel has been
  297  *      initialized.  In particular, current_thread() or kernel_map
  298  *      (or both) may be null.
  299  */
  300 
  301 bool
  302 db_map_equal(vm_map_t map1, vm_map_t map2)
  303 {
  304         return ((map1 == map2) ||
  305                 ((map1 == NULL) && (map2 == kernel_map)) ||
  306                 ((map1 == kernel_map) && (map2 == NULL)));
  307 }
  308 
  309 bool
  310 db_map_current(vm_map_t map)
  311 {
  312 #if 0
  313         thread_t        thread;
  314 
  315         return ((map == NULL) ||
  316                 (map == kernel_map) ||
  317                 (((thread = current_thread()) != NULL) &&
  318                  (map == thread->task->map)));
  319 #else
  320         return (true);
  321 #endif
  322 }
  323 
  324 vm_map_t
  325 db_map_addr(vm_offset_t addr)
  326 {
  327 #if 0
  328         thread_t        thread;
  329 
  330         /*
  331          *      We want to return kernel_map for all
  332          *      non-user addresses, even when debugging
  333          *      kernel tasks with their own maps.
  334          */
  335 
  336         if ((VM_MIN_ADDRESS <= addr) &&
  337             (addr < VM_MAX_ADDRESS) &&
  338             ((thread = current_thread()) != NULL))
  339             return thread->task->map;
  340         else
  341 #endif
  342             return kernel_map;
  343 }

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