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_watch.c

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    1 /*-
    2  * Mach Operating System
    3  * Copyright (c) 1991,1990 Carnegie Mellon University
    4  * All Rights Reserved.
    5  *
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  *
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  *
   16  * Carnegie Mellon requests users of this software to return to
   17  *
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  *
   23  * any improvements or extensions that they make and grant Carnegie the
   24  * rights to redistribute these changes.
   25  */
   26 /*
   27  *      Author: Richard P. Draves, Carnegie Mellon University
   28  *      Date:   10/90
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD: releng/11.0/sys/ddb/db_watch.c 283315 2015-05-23 14:59:27Z pfg $");
   33 
   34 #include <sys/param.h>
   35 #include <sys/kernel.h>
   36 #include <sys/lock.h>
   37 #include <sys/proc.h>
   38 
   39 #include <vm/vm.h>
   40 #include <vm/pmap.h>
   41 #include <vm/vm_map.h>
   42 
   43 #include <ddb/ddb.h>
   44 #include <ddb/db_watch.h>
   45 
   46 /*
   47  * Watchpoints.
   48  */
   49 
   50 static bool             db_watchpoints_inserted = true;
   51 
   52 #define NWATCHPOINTS    100
   53 static struct db_watchpoint     db_watch_table[NWATCHPOINTS];
   54 static db_watchpoint_t  db_next_free_watchpoint = &db_watch_table[0];
   55 static db_watchpoint_t  db_free_watchpoints = 0;
   56 static db_watchpoint_t  db_watchpoint_list = 0;
   57 
   58 static db_watchpoint_t  db_watchpoint_alloc(void);
   59 static void             db_watchpoint_free(db_watchpoint_t watch);
   60 static void             db_delete_watchpoint(vm_map_t map, db_addr_t addr);
   61 #ifdef notused
   62 static bool             db_find_watchpoint(vm_map_t map, db_addr_t addr,
   63                                         db_regs_t *regs);
   64 #endif
   65 static void             db_list_watchpoints(void);
   66 static void             db_set_watchpoint(vm_map_t map, db_addr_t addr,
   67                                        vm_size_t size);
   68 
   69 static db_watchpoint_t
   70 db_watchpoint_alloc(void)
   71 {
   72         db_watchpoint_t watch;
   73 
   74         if ((watch = db_free_watchpoints) != 0) {
   75             db_free_watchpoints = watch->link;
   76             return (watch);
   77         }
   78         if (db_next_free_watchpoint == &db_watch_table[NWATCHPOINTS]) {
   79             db_printf("All watchpoints used.\n");
   80             return (0);
   81         }
   82         watch = db_next_free_watchpoint;
   83         db_next_free_watchpoint++;
   84 
   85         return (watch);
   86 }
   87 
   88 static void
   89 db_watchpoint_free(db_watchpoint_t watch)
   90 {
   91         watch->link = db_free_watchpoints;
   92         db_free_watchpoints = watch;
   93 }
   94 
   95 static void
   96 db_set_watchpoint(vm_map_t map, db_addr_t addr, vm_size_t size)
   97 {
   98         db_watchpoint_t watch;
   99 
  100         if (map == NULL) {
  101             db_printf("No map.\n");
  102             return;
  103         }
  104 
  105         /*
  106          *      Should we do anything fancy with overlapping regions?
  107          */
  108 
  109         for (watch = db_watchpoint_list;
  110              watch != 0;
  111              watch = watch->link)
  112             if (db_map_equal(watch->map, map) &&
  113                 (watch->loaddr == addr) &&
  114                 (watch->hiaddr == addr+size)) {
  115                 db_printf("Already set.\n");
  116                 return;
  117             }
  118 
  119         watch = db_watchpoint_alloc();
  120         if (watch == 0) {
  121             db_printf("Too many watchpoints.\n");
  122             return;
  123         }
  124 
  125         watch->map = map;
  126         watch->loaddr = addr;
  127         watch->hiaddr = addr+size;
  128 
  129         watch->link = db_watchpoint_list;
  130         db_watchpoint_list = watch;
  131 
  132         db_watchpoints_inserted = false;
  133 }
  134 
  135 static void
  136 db_delete_watchpoint(vm_map_t map, db_addr_t addr)
  137 {
  138         db_watchpoint_t watch;
  139         db_watchpoint_t *prev;
  140 
  141         for (prev = &db_watchpoint_list;
  142              (watch = *prev) != 0;
  143              prev = &watch->link)
  144             if (db_map_equal(watch->map, map) &&
  145                 (watch->loaddr <= addr) &&
  146                 (addr < watch->hiaddr)) {
  147                 *prev = watch->link;
  148                 db_watchpoint_free(watch);
  149                 return;
  150             }
  151 
  152         db_printf("Not set.\n");
  153 }
  154 
  155 static void
  156 db_list_watchpoints(void)
  157 {
  158         db_watchpoint_t watch;
  159 
  160         if (db_watchpoint_list == 0) {
  161             db_printf("No watchpoints set\n");
  162             return;
  163         }
  164 
  165 #ifdef __LP64__
  166         db_printf(" Map                Address          Size\n");
  167 #else
  168         db_printf(" Map        Address  Size\n");
  169 #endif
  170         for (watch = db_watchpoint_list;
  171              watch != 0;
  172              watch = watch->link)
  173 #ifdef __LP64__
  174             db_printf("%s%16p  %16lx  %lx\n",
  175 #else
  176             db_printf("%s%8p  %8lx  %lx\n",
  177 #endif
  178                       db_map_current(watch->map) ? "*" : " ",
  179                       (void *)watch->map, (long)watch->loaddr,
  180                       (long)watch->hiaddr - (long)watch->loaddr);
  181 }
  182 
  183 /* Delete watchpoint */
  184 /*ARGSUSED*/
  185 void
  186 db_deletewatch_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
  187    char *modif)
  188 {
  189         db_delete_watchpoint(db_map_addr(addr), addr);
  190 }
  191 
  192 /* Set watchpoint */
  193 /*ARGSUSED*/
  194 void
  195 db_watchpoint_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
  196    char *modif)
  197 {
  198         vm_size_t       size;
  199         db_expr_t       value;
  200 
  201         if (db_expression(&value))
  202             size = (vm_size_t) value;
  203         else
  204             size = 4;
  205         db_skip_to_eol();
  206 
  207         db_set_watchpoint(db_map_addr(addr), addr, size);
  208 }
  209 
  210 /*
  211  * At least one non-optional show-command must be implemented using
  212  * DB_SHOW_COMMAND() so that db_show_cmd_set gets created.  Here is one.
  213  */
  214 DB_SHOW_COMMAND(watches, db_listwatch_cmd)
  215 {
  216         db_list_watchpoints();
  217         db_md_list_watchpoints();
  218 }
  219 
  220 void
  221 db_set_watchpoints(void)
  222 {
  223         db_watchpoint_t watch;
  224 
  225         if (!db_watchpoints_inserted) {
  226             for (watch = db_watchpoint_list;
  227                  watch != 0;
  228                  watch = watch->link)
  229                 pmap_protect(watch->map->pmap,
  230                              trunc_page(watch->loaddr),
  231                              round_page(watch->hiaddr),
  232                              VM_PROT_READ);
  233 
  234             db_watchpoints_inserted = true;
  235         }
  236 }
  237 
  238 void
  239 db_clear_watchpoints(void)
  240 {
  241         db_watchpoints_inserted = false;
  242 }
  243 
  244 #ifdef notused
  245 static bool
  246 db_find_watchpoint(vm_map_t map, db_addr_t addr, db_regs_t regs)
  247 {
  248         db_watchpoint_t watch;
  249         db_watchpoint_t found = 0;
  250 
  251         for (watch = db_watchpoint_list;
  252              watch != 0;
  253              watch = watch->link)
  254             if (db_map_equal(watch->map, map)) {
  255                 if ((watch->loaddr <= addr) &&
  256                     (addr < watch->hiaddr))
  257                     return (true);
  258                 else if ((trunc_page(watch->loaddr) <= addr) &&
  259                          (addr < round_page(watch->hiaddr)))
  260                     found = watch;
  261             }
  262 
  263         /*
  264          *      We didn't hit exactly on a watchpoint, but we are
  265          *      in a protected region.  We want to single-step
  266          *      and then re-protect.
  267          */
  268 
  269         if (found) {
  270             db_watchpoints_inserted = false;
  271             db_single_step(regs);
  272         }
  273 
  274         return (false);
  275 }
  276 #endif
  277 
  278 
  279 
  280 /* Delete hardware watchpoint */
  281 /*ARGSUSED*/
  282 void
  283 db_deletehwatch_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
  284    char *modif)
  285 {
  286         int rc;
  287 
  288         if (count < 0)
  289                 count = 4;
  290 
  291         rc = db_md_clr_watchpoint(addr, count);
  292         if (rc < 0)
  293                 db_printf("hardware watchpoint could not be deleted\n");
  294 }
  295 
  296 /* Set hardware watchpoint */
  297 /*ARGSUSED*/
  298 void
  299 db_hwatchpoint_cmd(db_expr_t addr, bool have_addr, db_expr_t count,
  300    char *modif)
  301 {
  302         int rc;
  303 
  304         if (count < 0)
  305                 count = 4;
  306 
  307         rc = db_md_set_watchpoint(addr, count);
  308         if (rc < 0)
  309                 db_printf("hardware watchpoint could not be set\n");
  310 }

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