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

     /*      $OpenBSD: db_sym.c,v 1.56 2021/07/09 20:59:17 jasper Exp $      */
     /*      $NetBSD: db_sym.c,v 1.24 2000/08/11 22:50:47 tv Exp $   */
     
     /*
      * Mach Operating System
      * Copyright (c) 1993,1992,1991,1990 Carnegie Mellon University
      * All Rights Reserved.
      *
      * Permission to use, copy, modify and distribute this software and its
     * documentation is hereby granted, provided that both the copyright
     * notice and this permission notice appear in all copies of the
     * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     *
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
     * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     *
     * Carnegie Mellon requests users of this software to return to
     *
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     *
     * any improvements or extensions that they make and grant Carnegie Mellon
     * the rights to redistribute these changes.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    
    #include <machine/db_machdep.h>
    
    #include <ddb/db_lex.h>
    #include <ddb/db_sym.h>
    #include <ddb/db_output.h>
    #include <ddb/db_command.h>
    
    extern char end[];
    
    /*
     * Initialize the kernel debugger by initializing the master symbol
     * table.  Note that if initializing the master symbol table fails,
     * no other symbol tables can be loaded.
     */
    void
    ddb_init(void)
    {
            const char *name = "bsd";
            extern char *esym;
    #if defined(__sparc64__) || defined(__mips__) || defined(__amd64__) || \
        defined(__i386__)
            extern char *ssym;
    #endif
            char *xssym, *xesym;
    
            xesym = esym;
    #if defined(__sparc64__) || defined(__mips__) || defined(__amd64__) || \
        defined(__i386__)
            xssym = ssym;
    #else
            xssym = (char *)&end;
    #endif
            /*
             * Do this check now for the master symbol table to avoid printing
             * the message N times.
             */
            if ((((vaddr_t)xssym) & (sizeof(long) - 1)) != 0) {
                    printf("[ %s symbol table has bad start address %p ]\n",
                        name, xssym);
                    return;
            }
    
            if (xesym != NULL && xesym != xssym) {
                    if (db_elf_sym_init((vaddr_t)xesym - (vaddr_t)xssym, xssym,
                        xesym, name) == 1)
                            return;
            }
    
            printf("[ no symbol table formats found ]\n");
    }
    
    int
    db_eqname(char *src, char *dst, int c)
    {
            if (!strcmp(src, dst))
                    return (1);
            if (src[0] == c)
                    return (!strcmp(src+1,dst));
            return (0);
    }
    
    /*
     * Find the closest symbol to val, and return its name
     * and the difference between val and the symbol found.
     */
    Elf_Sym *
    db_search_symbol(vaddr_t val, db_strategy_t strategy, db_expr_t *offp)
   {
           unsigned int    diff;
           db_expr_t       newdiff;
           Elf_Sym         *ret = NULL, *sym;
   
           newdiff = diff = ~0;
           sym = db_elf_sym_search(val, strategy, &newdiff);
           if (newdiff < diff) {
                   diff = newdiff;
                   ret = sym;
           }
           *offp = diff;
           return ret;
   }
   
   /*
    * Print the closest symbol to a value.
    *
    * After matching the symbol according to the given strategy
    * we print it in the name+offset format, provided the symbol's
    * value is close enough (eg smaller than db_maxoff).
    * We also attempt to print [filename:linenum] when applicable
    * (eg for procedure names).
    *
    * If we could not find a reasonable name+offset representation,
    * then we just print the value in hex.  Small values might get
    * bogus symbol associations, e.g. 3 might get some absolute
    * value like _INCLUDE_VERSION or something, therefore we do
    * not accept symbols whose value is zero (and use plain hex).
    * Also, avoid printing as "end+0x????" which is useless.
    * The variable db_lastsym is used instead of "end" in case we
    * add support for symbols in loadable driver modules.
    */
   unsigned long   db_lastsym = (unsigned long)end;
   unsigned int    db_maxoff = 0x10000000;
   
   
   void
   db_printsym(db_expr_t off, db_strategy_t strategy,
       int (*pr)(const char *, ...))
   {
           db_expr_t       d;
           char            *filename;
           char            *name;
           db_expr_t       value;
           int             linenum;
           Elf_Sym         *cursym;
           char            buf[DB_FORMAT_BUF_SIZE];
   
           if (off <= db_lastsym) {
                   cursym = db_search_symbol(off, strategy, &d);
                   db_symbol_values(cursym, &name, &value);
                   if (name && (d < db_maxoff) && value) {
                           (*pr)("%s", name);
                           if (d) {
                                   (*pr)("+%s", db_format(buf, sizeof(buf),
                                       d, DB_FORMAT_R, 1, 0));
                           }
                           if (strategy == DB_STGY_PROC) {
                                   if (db_elf_line_at_pc(cursym, &filename,
                                       &linenum, off))
                                           (*pr)(" [%s:%d]", filename, linenum);
                           }
                           return;
                   }
           }
   
           (*pr)("%s", db_format(buf, sizeof(buf), off, DB_FORMAT_N, 1, 0));
           return;
   }

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