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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sys/ddb/db_sym.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: David B. Golub, Carnegie Mellon University
   28  *      Date:   7/90
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD: releng/9.1/sys/ddb/db_sym.c 206639 2010-04-14 23:06:07Z julian $");
   33 
   34 #include <sys/param.h>
   35 #include <sys/pcpu.h>
   36 #include <sys/smp.h>
   37 #include <sys/systm.h>
   38 
   39 #include <net/vnet.h>
   40 
   41 #include <ddb/ddb.h>
   42 #include <ddb/db_sym.h>
   43 #include <ddb/db_variables.h>
   44 
   45 #include <opt_ddb.h>
   46 
   47 /*
   48  * Multiple symbol tables
   49  */
   50 #ifndef MAXNOSYMTABS
   51 #define MAXNOSYMTABS    3       /* mach, ux, emulator */
   52 #endif
   53 
   54 static db_symtab_t      db_symtabs[MAXNOSYMTABS] = {{0,},};
   55 static int db_nsymtab = 0;
   56 
   57 static db_symtab_t      *db_last_symtab; /* where last symbol was found */
   58 
   59 static c_db_sym_t       db_lookup( const char *symstr);
   60 static char             *db_qualify(c_db_sym_t sym, char *symtabname);
   61 static boolean_t        db_symbol_is_ambiguous(c_db_sym_t sym);
   62 static boolean_t        db_line_at_pc(c_db_sym_t, char **, int *, db_expr_t);
   63 
   64 static int db_cpu = -1;
   65 
   66 #ifdef VIMAGE
   67 static void *db_vnet = NULL;
   68 #endif
   69 
   70 /*
   71  * Validate the CPU number used to interpret per-CPU variables so we can
   72  * avoid later confusion if an invalid CPU is requested.
   73  */
   74 int
   75 db_var_db_cpu(struct db_variable *vp, db_expr_t *valuep, int op)
   76 {
   77 
   78         switch (op) {
   79         case DB_VAR_GET:
   80                 *valuep = db_cpu;
   81                 return (1);
   82 
   83         case DB_VAR_SET:
   84                 if (*(int *)valuep < -1 && *(int *)valuep > mp_maxid) {
   85                         db_printf("Invalid value: %d", *(int*)valuep);
   86                         return (0);
   87                 }
   88                 db_cpu = *(int *)valuep;
   89                 return (1);
   90 
   91         default:
   92                 db_printf("db_var_db_cpu: unknown operation\n");
   93                 return (0);
   94         }
   95 }
   96 
   97 /*
   98  * Read-only variable reporting the current CPU, which is what we use when
   99  * db_cpu is set to -1.
  100  */
  101 int
  102 db_var_curcpu(struct db_variable *vp, db_expr_t *valuep, int op)
  103 {
  104 
  105         switch (op) {
  106         case DB_VAR_GET:
  107                 *valuep = curcpu;
  108                 return (1);
  109 
  110         case DB_VAR_SET:
  111                 db_printf("Read-only variable.\n");
  112                 return (0);
  113 
  114         default:
  115                 db_printf("db_var_curcpu: unknown operation\n");
  116                 return (0);
  117         }
  118 }
  119 
  120 #ifdef VIMAGE
  121 /*
  122  * Validate the virtual network pointer used to interpret per-vnet global
  123  * variable expansion.  Right now we don't do much here, really we should
  124  * walk the global vnet list to check it's an OK pointer.
  125  */
  126 int
  127 db_var_db_vnet(struct db_variable *vp, db_expr_t *valuep, int op)
  128 {
  129 
  130         switch (op) {
  131         case DB_VAR_GET:
  132                 *valuep = (db_expr_t)db_vnet;
  133                 return (1);
  134 
  135         case DB_VAR_SET:
  136                 db_vnet = *(void **)valuep;
  137                 return (1);
  138 
  139         default:
  140                 db_printf("db_var_db_vnet: unknown operation\n");
  141                 return (0);
  142         }
  143 }
  144 
  145 /*
  146  * Read-only variable reporting the current vnet, which is what we use when
  147  * db_vnet is set to NULL.
  148  */
  149 int
  150 db_var_curvnet(struct db_variable *vp, db_expr_t *valuep, int op)
  151 {
  152 
  153         switch (op) {
  154         case DB_VAR_GET:
  155                 *valuep = (db_expr_t)curvnet;
  156                 return (1);
  157 
  158         case DB_VAR_SET:
  159                 db_printf("Read-only variable.\n");
  160                 return (0);
  161 
  162         default:
  163                 db_printf("db_var_curcpu: unknown operation\n");
  164                 return (0);
  165         }
  166 }
  167 #endif
  168 
  169 /*
  170  * Add symbol table, with given name, to list of symbol tables.
  171  */
  172 void
  173 db_add_symbol_table(start, end, name, ref)
  174         char *start;
  175         char *end;
  176         char *name;
  177         char *ref;
  178 {
  179         if (db_nsymtab >= MAXNOSYMTABS) {
  180                 printf ("No slots left for %s symbol table", name);
  181                 panic ("db_sym.c: db_add_symbol_table");
  182         }
  183 
  184         db_symtabs[db_nsymtab].start = start;
  185         db_symtabs[db_nsymtab].end = end;
  186         db_symtabs[db_nsymtab].name = name;
  187         db_symtabs[db_nsymtab].private = ref;
  188         db_nsymtab++;
  189 }
  190 
  191 /*
  192  *  db_qualify("vm_map", "ux") returns "unix:vm_map".
  193  *
  194  *  Note: return value points to static data whose content is
  195  *  overwritten by each call... but in practice this seems okay.
  196  */
  197 static char *
  198 db_qualify(sym, symtabname)
  199         c_db_sym_t      sym;
  200         register char   *symtabname;
  201 {
  202         const char      *symname;
  203         static char     tmp[256];
  204 
  205         db_symbol_values(sym, &symname, 0);
  206         snprintf(tmp, sizeof(tmp), "%s:%s", symtabname, symname);
  207         return tmp;
  208 }
  209 
  210 
  211 boolean_t
  212 db_eqname(src, dst, c)
  213         const char *src;
  214         const char *dst;
  215         int c;
  216 {
  217         if (!strcmp(src, dst))
  218             return (TRUE);
  219         if (src[0] == c)
  220             return (!strcmp(src+1,dst));
  221         return (FALSE);
  222 }
  223 
  224 boolean_t
  225 db_value_of_name(name, valuep)
  226         const char      *name;
  227         db_expr_t       *valuep;
  228 {
  229         c_db_sym_t      sym;
  230 
  231         sym = db_lookup(name);
  232         if (sym == C_DB_SYM_NULL)
  233             return (FALSE);
  234         db_symbol_values(sym, &name, valuep);
  235         return (TRUE);
  236 }
  237 
  238 boolean_t
  239 db_value_of_name_pcpu(name, valuep)
  240         const char      *name;
  241         db_expr_t       *valuep;
  242 {
  243         static char     tmp[256];
  244         db_expr_t       value;
  245         c_db_sym_t      sym;
  246         int             cpu;
  247 
  248         if (db_cpu != -1)
  249                 cpu = db_cpu;
  250         else
  251                 cpu = curcpu;
  252         snprintf(tmp, sizeof(tmp), "pcpu_entry_%s", name);
  253         sym = db_lookup(tmp);
  254         if (sym == C_DB_SYM_NULL)
  255                 return (FALSE);
  256         db_symbol_values(sym, &name, &value);
  257         if (value < DPCPU_START || value >= DPCPU_STOP)
  258                 return (FALSE);
  259         *valuep = (db_expr_t)((uintptr_t)value + dpcpu_off[cpu]);
  260         return (TRUE);
  261 }
  262 
  263 boolean_t
  264 db_value_of_name_vnet(name, valuep)
  265         const char      *name;
  266         db_expr_t       *valuep;
  267 {
  268 #ifdef VIMAGE
  269         static char     tmp[256];
  270         db_expr_t       value;
  271         c_db_sym_t      sym;
  272         struct vnet     *vnet;
  273 
  274         if (db_vnet != NULL)
  275                 vnet = db_vnet;
  276         else
  277                 vnet = curvnet;
  278         snprintf(tmp, sizeof(tmp), "vnet_entry_%s", name);
  279         sym = db_lookup(tmp);
  280         if (sym == C_DB_SYM_NULL)
  281                 return (FALSE);
  282         db_symbol_values(sym, &name, &value);
  283         if (value < VNET_START || value >= VNET_STOP)
  284                 return (FALSE);
  285         *valuep = (db_expr_t)((uintptr_t)value + vnet->vnet_data_base);
  286         return (TRUE);
  287 #else
  288         return (FALSE);
  289 #endif
  290 }
  291 
  292 /*
  293  * Lookup a symbol.
  294  * If the symbol has a qualifier (e.g., ux:vm_map),
  295  * then only the specified symbol table will be searched;
  296  * otherwise, all symbol tables will be searched.
  297  */
  298 static c_db_sym_t
  299 db_lookup(symstr)
  300         const char *symstr;
  301 {
  302         c_db_sym_t sp;
  303         register int i;
  304         int symtab_start = 0;
  305         int symtab_end = db_nsymtab;
  306         register const char *cp;
  307 
  308         /*
  309          * Look for, remove, and remember any symbol table specifier.
  310          */
  311         for (cp = symstr; *cp; cp++) {
  312                 if (*cp == ':') {
  313                         for (i = 0; i < db_nsymtab; i++) {
  314                                 int n = strlen(db_symtabs[i].name);
  315 
  316                                 if (
  317                                     n == (cp - symstr) &&
  318                                     strncmp(symstr, db_symtabs[i].name, n) == 0
  319                                 ) {
  320                                         symtab_start = i;
  321                                         symtab_end = i + 1;
  322                                         break;
  323                                 }
  324                         }
  325                         if (i == db_nsymtab) {
  326                                 db_error("invalid symbol table name");
  327                         }
  328                         symstr = cp+1;
  329                 }
  330         }
  331 
  332         /*
  333          * Look in the specified set of symbol tables.
  334          * Return on first match.
  335          */
  336         for (i = symtab_start; i < symtab_end; i++) {
  337                 sp = X_db_lookup(&db_symtabs[i], symstr);
  338                 if (sp) {
  339                         db_last_symtab = &db_symtabs[i];
  340                         return sp;
  341                 }
  342         }
  343         return 0;
  344 }
  345 
  346 /*
  347  * If TRUE, check across symbol tables for multiple occurrences
  348  * of a name.  Might slow things down quite a bit.
  349  */
  350 static volatile boolean_t db_qualify_ambiguous_names = FALSE;
  351 
  352 /*
  353  * Does this symbol name appear in more than one symbol table?
  354  * Used by db_symbol_values to decide whether to qualify a symbol.
  355  */
  356 static boolean_t
  357 db_symbol_is_ambiguous(sym)
  358         c_db_sym_t      sym;
  359 {
  360         const char      *sym_name;
  361         register int    i;
  362         register
  363         boolean_t       found_once = FALSE;
  364 
  365         if (!db_qualify_ambiguous_names)
  366                 return FALSE;
  367 
  368         db_symbol_values(sym, &sym_name, 0);
  369         for (i = 0; i < db_nsymtab; i++) {
  370                 if (X_db_lookup(&db_symtabs[i], sym_name)) {
  371                         if (found_once)
  372                                 return TRUE;
  373                         found_once = TRUE;
  374                 }
  375         }
  376         return FALSE;
  377 }
  378 
  379 /*
  380  * Find the closest symbol to val, and return its name
  381  * and the difference between val and the symbol found.
  382  */
  383 c_db_sym_t
  384 db_search_symbol( val, strategy, offp)
  385         register db_addr_t      val;
  386         db_strategy_t           strategy;
  387         db_expr_t               *offp;
  388 {
  389         register
  390         unsigned int    diff;
  391         size_t          newdiff;
  392         register int    i;
  393         c_db_sym_t      ret = C_DB_SYM_NULL, sym;
  394 
  395         newdiff = diff = ~0;
  396         for (i = 0; i < db_nsymtab; i++) {
  397             sym = X_db_search_symbol(&db_symtabs[i], val, strategy, &newdiff);
  398             if (newdiff < diff) {
  399                 db_last_symtab = &db_symtabs[i];
  400                 diff = newdiff;
  401                 ret = sym;
  402             }
  403         }
  404         *offp = diff;
  405         return ret;
  406 }
  407 
  408 /*
  409  * Return name and value of a symbol
  410  */
  411 void
  412 db_symbol_values(sym, namep, valuep)
  413         c_db_sym_t      sym;
  414         const char      **namep;
  415         db_expr_t       *valuep;
  416 {
  417         db_expr_t       value;
  418 
  419         if (sym == DB_SYM_NULL) {
  420                 *namep = 0;
  421                 return;
  422         }
  423 
  424         X_db_symbol_values(db_last_symtab, sym, namep, &value);
  425 
  426         if (db_symbol_is_ambiguous(sym))
  427                 *namep = db_qualify(sym, db_last_symtab->name);
  428         if (valuep)
  429                 *valuep = value;
  430 }
  431 
  432 
  433 /*
  434  * Print a the closest symbol to value
  435  *
  436  * After matching the symbol according to the given strategy
  437  * we print it in the name+offset format, provided the symbol's
  438  * value is close enough (eg smaller than db_maxoff).
  439  * We also attempt to print [filename:linenum] when applicable
  440  * (eg for procedure names).
  441  *
  442  * If we could not find a reasonable name+offset representation,
  443  * then we just print the value in hex.  Small values might get
  444  * bogus symbol associations, e.g. 3 might get some absolute
  445  * value like _INCLUDE_VERSION or something, therefore we do
  446  * not accept symbols whose value is "small" (and use plain hex).
  447  */
  448 
  449 db_expr_t       db_maxoff = 0x10000;
  450 
  451 void
  452 db_printsym(off, strategy)
  453         db_expr_t       off;
  454         db_strategy_t   strategy;
  455 {
  456         db_expr_t       d;
  457         char            *filename;
  458         const char      *name;
  459         db_expr_t       value;
  460         int             linenum;
  461         c_db_sym_t      cursym;
  462 
  463         cursym = db_search_symbol(off, strategy, &d);
  464         db_symbol_values(cursym, &name, &value);
  465         if (name == 0)
  466                 value = off;
  467         if (value >= DB_SMALL_VALUE_MIN && value <= DB_SMALL_VALUE_MAX) {
  468                 db_printf("%+#lr", (long)off);
  469                 return;
  470         }
  471         if (name == 0 || d >= (unsigned long)db_maxoff) {
  472                 db_printf("%#lr", (unsigned long)off);
  473                 return;
  474         }
  475 #ifdef DDB_NUMSYM
  476         db_printf("%#lr = %s", (unsigned long)off, name);
  477 #else
  478         db_printf("%s", name);
  479 #endif
  480         if (d)
  481                 db_printf("+%+#lr", (long)d);
  482         if (strategy == DB_STGY_PROC) {
  483                 if (db_line_at_pc(cursym, &filename, &linenum, off))
  484                         db_printf(" [%s:%d]", filename, linenum);
  485         }
  486 }
  487 
  488 static boolean_t
  489 db_line_at_pc( sym, filename, linenum, pc)
  490         c_db_sym_t      sym;
  491         char            **filename;
  492         int             *linenum;
  493         db_expr_t       pc;
  494 {
  495         return X_db_line_at_pc( db_last_symtab, sym, filename, linenum, pc);
  496 }
  497 
  498 int
  499 db_sym_numargs(sym, nargp, argnames)
  500         c_db_sym_t      sym;
  501         int             *nargp;
  502         char            **argnames;
  503 {
  504         return X_db_sym_numargs(db_last_symtab, sym, nargp, argnames);
  505 }

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