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

     /*-
      * SPDX-License-Identifier: MIT-CMU
      *
      * Mach Operating System
      * Copyright (c) 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
     * 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 the
     * rights to redistribute these changes.
     */
    /*
     *      Author: David B. Golub, Carnegie Mellon University
     *      Date:   7/90
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_kstack_pages.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/pcpu.h>
    #include <sys/proc.h>
    #include <sys/smp.h>
    #include <sys/sysent.h>
    
    #include <net/vnet.h>
    
    #include <ddb/ddb.h>
    #include <ddb/db_sym.h>
    #include <ddb/db_variables.h>
    
    #include "opt_ddb.h"
    
    /*
     * Multiple symbol tables
     */
    #ifndef MAXNOSYMTABS
    #define MAXNOSYMTABS    3       /* mach, ux, emulator */
    #endif
    
    static db_symtab_t      db_symtabs[MAXNOSYMTABS] = {{0,},};
    static int db_nsymtab = 0;
    
    static db_symtab_t      *db_last_symtab; /* where last symbol was found */
    
    static c_db_sym_t       db_lookup( const char *symstr);
    static char             *db_qualify(c_db_sym_t sym, char *symtabname);
    static bool             db_symbol_is_ambiguous(c_db_sym_t sym);
    static bool             db_line_at_pc(c_db_sym_t, char **, int *, db_expr_t);
    
    static int db_cpu = -1;
    
    #ifdef VIMAGE
    static void *db_vnet = NULL;
    #endif
    
    /*
     * Validate the CPU number used to interpret per-CPU variables so we can
     * avoid later confusion if an invalid CPU is requested.
     */
    int
    db_var_db_cpu(struct db_variable *vp, db_expr_t *valuep, int op)
    {
    
            switch (op) {
            case DB_VAR_GET:
                    *valuep = db_cpu;
                    return (1);
    
            case DB_VAR_SET:
                    if (*(int *)valuep < -1 || *(int *)valuep > mp_maxid) {
                            db_printf("Invalid value: %d\n", *(int*)valuep);
                            return (0);
                    }
                    db_cpu = *(int *)valuep;
                    return (1);
    
            default:
                    db_printf("db_var_db_cpu: unknown operation\n");
                    return (0);
           }
   }
   
   /*
    * Read-only variable reporting the current CPU, which is what we use when
    * db_cpu is set to -1.
    */
   int
   db_var_curcpu(struct db_variable *vp, db_expr_t *valuep, int op)
   {
   
           switch (op) {
           case DB_VAR_GET:
                   *valuep = curcpu;
                   return (1);
   
           case DB_VAR_SET:
                   db_printf("Read-only variable.\n");
                   return (0);
   
           default:
                   db_printf("db_var_curcpu: unknown operation\n");
                   return (0);
           }
   }
   
   #ifdef VIMAGE
   /*
    * Validate the virtual network pointer used to interpret per-vnet global
    * variable expansion.  Right now we don't do much here, really we should
    * walk the global vnet list to check it's an OK pointer.
    */
   int
   db_var_db_vnet(struct db_variable *vp, db_expr_t *valuep, int op)
   {
   
           switch (op) {
           case DB_VAR_GET:
                   *valuep = (db_expr_t)db_vnet;
                   return (1);
   
           case DB_VAR_SET:
                   db_vnet = *(void **)valuep;
                   return (1);
   
           default:
                   db_printf("db_var_db_vnet: unknown operation\n");
                   return (0);
           }
   }
   
   /*
    * Read-only variable reporting the current vnet, which is what we use when
    * db_vnet is set to NULL.
    */
   int
   db_var_curvnet(struct db_variable *vp, db_expr_t *valuep, int op)
   {
   
           switch (op) {
           case DB_VAR_GET:
                   *valuep = (db_expr_t)curvnet;
                   return (1);
   
           case DB_VAR_SET:
                   db_printf("Read-only variable.\n");
                   return (0);
   
           default:
                   db_printf("db_var_curvnet: unknown operation\n");
                   return (0);
           }
   }
   #endif
   
   /*
    * Add symbol table, with given name, to list of symbol tables.
    */
   void
   db_add_symbol_table(char *start, char *end, char *name, char *ref)
   {
           if (db_nsymtab >= MAXNOSYMTABS) {
                   printf ("No slots left for %s symbol table", name);
                   panic ("db_sym.c: db_add_symbol_table");
           }
   
           db_symtabs[db_nsymtab].start = start;
           db_symtabs[db_nsymtab].end = end;
           db_symtabs[db_nsymtab].name = name;
           db_symtabs[db_nsymtab].private = ref;
           db_nsymtab++;
   }
   
   /*
    *  db_qualify("vm_map", "ux") returns "unix:vm_map".
    *
    *  Note: return value points to static data whose content is
    *  overwritten by each call... but in practice this seems okay.
    */
   static char *
   db_qualify(c_db_sym_t sym, char *symtabname)
   {
           const char      *symname;
           static char     tmp[256];
   
           db_symbol_values(sym, &symname, 0);
           snprintf(tmp, sizeof(tmp), "%s:%s", symtabname, symname);
           return tmp;
   }
   
   bool
   db_eqname(const char *src, const char *dst, int c)
   {
           if (!strcmp(src, dst))
               return (true);
           if (src[0] == c)
               return (!strcmp(src+1,dst));
           return (false);
   }
   
   bool
   db_value_of_name(const char *name, db_expr_t *valuep)
   {
           c_db_sym_t      sym;
   
           sym = db_lookup(name);
           if (sym == C_DB_SYM_NULL)
               return (false);
           db_symbol_values(sym, &name, valuep);
           return (true);
   }
   
   bool
   db_value_of_name_pcpu(const char *name, db_expr_t *valuep)
   {
           static char     tmp[256];
           db_expr_t       value;
           c_db_sym_t      sym;
           int             cpu;
   
           if (db_cpu != -1)
                   cpu = db_cpu;
           else
                   cpu = curcpu;
           snprintf(tmp, sizeof(tmp), "pcpu_entry_%s", name);
           sym = db_lookup(tmp);
           if (sym == C_DB_SYM_NULL)
                   return (false);
           db_symbol_values(sym, &name, &value);
           if (value < DPCPU_START || value >= DPCPU_STOP)
                   return (false);
           *valuep = (db_expr_t)((uintptr_t)value + dpcpu_off[cpu]);
           return (true);
   }
   
   bool
   db_value_of_name_vnet(const char *name, db_expr_t *valuep)
   {
   #ifdef VIMAGE
           static char     tmp[256];
           db_expr_t       value;
           c_db_sym_t      sym;
           struct vnet     *vnet;
   
           if (db_vnet != NULL)
                   vnet = db_vnet;
           else
                   vnet = curvnet;
           snprintf(tmp, sizeof(tmp), "vnet_entry_%s", name);
           sym = db_lookup(tmp);
           if (sym == C_DB_SYM_NULL)
                   return (false);
           db_symbol_values(sym, &name, &value);
           if (value < VNET_START || value >= VNET_STOP)
                   return (false);
           *valuep = (db_expr_t)((uintptr_t)value + vnet->vnet_data_base);
           return (true);
   #else
           return (false);
   #endif
   }
   
   /*
    * Lookup a symbol.
    * If the symbol has a qualifier (e.g., ux:vm_map),
    * then only the specified symbol table will be searched;
    * otherwise, all symbol tables will be searched.
    */
   static c_db_sym_t
   db_lookup(const char *symstr)
   {
           c_db_sym_t sp;
           int i;
           int symtab_start = 0;
           int symtab_end = db_nsymtab;
           const char *cp;
   
           /*
            * Look for, remove, and remember any symbol table specifier.
            */
           for (cp = symstr; *cp; cp++) {
                   if (*cp == ':') {
                           for (i = 0; i < db_nsymtab; i++) {
                                   int n = strlen(db_symtabs[i].name);
   
                                   if (
                                       n == (cp - symstr) &&
                                       strncmp(symstr, db_symtabs[i].name, n) == 0
                                   ) {
                                           symtab_start = i;
                                           symtab_end = i + 1;
                                           break;
                                   }
                           }
                           if (i == db_nsymtab) {
                                   db_error("invalid symbol table name");
                           }
                           symstr = cp+1;
                   }
           }
   
           /*
            * Look in the specified set of symbol tables.
            * Return on first match.
            */
           for (i = symtab_start; i < symtab_end; i++) {
                   sp = X_db_lookup(&db_symtabs[i], symstr);
                   if (sp) {
                           db_last_symtab = &db_symtabs[i];
                           return sp;
                   }
           }
           return 0;
   }
   
   /*
    * If true, check across symbol tables for multiple occurrences
    * of a name.  Might slow things down quite a bit.
    */
   static volatile bool db_qualify_ambiguous_names = false;
   
   /*
    * Does this symbol name appear in more than one symbol table?
    * Used by db_symbol_values to decide whether to qualify a symbol.
    */
   static bool
   db_symbol_is_ambiguous(c_db_sym_t sym)
   {
           const char      *sym_name;
           int             i;
           bool            found_once = false;
   
           if (!db_qualify_ambiguous_names)
                   return (false);
   
           db_symbol_values(sym, &sym_name, 0);
           for (i = 0; i < db_nsymtab; i++) {
                   if (X_db_lookup(&db_symtabs[i], sym_name)) {
                           if (found_once)
                                   return (true);
                           found_once = true;
                   }
           }
           return (false);
   }
   
   /*
    * Find the closest symbol to val, and return its name
    * and the difference between val and the symbol found.
    */
   c_db_sym_t
   db_search_symbol(db_addr_t val, db_strategy_t strategy, db_expr_t *offp)
   {
           unsigned int    diff;
           size_t          newdiff;
           int             i;
           c_db_sym_t      ret, sym;
   
           /*
            * The kernel will never map the first page, so any symbols in that
            * range cannot refer to addresses.  Some third-party assembly files
            * define internal constants which appear in their symbol table.
            * Avoiding the lookup for those symbols avoids replacing small offsets
            * with those symbols during disassembly.
            */
           if (val < PAGE_SIZE) {
                   *offp = 0;
                   return (C_DB_SYM_NULL);
           }
   
           ret = C_DB_SYM_NULL;
           newdiff = diff = val;
           for (i = 0; i < db_nsymtab; i++) {
               sym = X_db_search_symbol(&db_symtabs[i], val, strategy, &newdiff);
               if ((uintmax_t)newdiff < (uintmax_t)diff) {
                   db_last_symtab = &db_symtabs[i];
                   diff = newdiff;
                   ret = sym;
               }
           }
           *offp = diff;
           return ret;
   }
   
   /*
    * Return name and value of a symbol
    */
   void
   db_symbol_values(c_db_sym_t sym, const char **namep, db_expr_t *valuep)
   {
           db_expr_t       value;
   
           if (sym == DB_SYM_NULL) {
                   *namep = NULL;
                   return;
           }
   
           X_db_symbol_values(db_last_symtab, sym, namep, &value);
   
           if (db_symbol_is_ambiguous(sym))
                   *namep = db_qualify(sym, db_last_symtab->name);
           if (valuep)
                   *valuep = value;
   }
   
   /*
    * Print a the closest symbol to 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 "small" (and use plain hex).
    */
   
   db_expr_t       db_maxoff = 0x10000;
   
   void
   db_printsym(db_expr_t off, db_strategy_t strategy)
   {
           db_expr_t       d;
           char            *filename;
           const char      *name;
           int             linenum;
           c_db_sym_t      cursym;
   
           if (off < 0 && off >= -db_maxoff) {
                   db_printf("%+#lr", (long)off);
                   return;
           }
           cursym = db_search_symbol(off, strategy, &d);
           db_symbol_values(cursym, &name, NULL);
           if (name == NULL || d >= (db_addr_t)db_maxoff) {
                   db_printf("%#lr", (unsigned long)off);
                   return;
           }
   #ifdef DDB_NUMSYM
           db_printf("%#lr = %s", (unsigned long)off, name);
   #else
           db_printf("%s", name);
   #endif
           if (d)
                   db_printf("+%+#lr", (long)d);
           if (strategy == DB_STGY_PROC) {
                   if (db_line_at_pc(cursym, &filename, &linenum, off))
                           db_printf(" [%s:%d]", filename, linenum);
           }
   }
   
   static bool
   db_line_at_pc(c_db_sym_t sym, char **filename, int *linenum, db_expr_t pc)
   {
           return (X_db_line_at_pc(db_last_symtab, sym, filename, linenum, pc));
   }
   
   bool
   db_sym_numargs(c_db_sym_t sym, int *nargp, char **argnames)
   {
           return (X_db_sym_numargs(db_last_symtab, sym, nargp, argnames));
   }
   
   void
   db_decode_syscall(struct thread *td, u_int number)
   {
           struct proc *p;
   
           db_printf(" (%u", number);
           p = (td != NULL) ? td->td_proc : NULL;
           if (p != NULL) {
                   db_printf(", %s, %s", p->p_sysent->sv_name,
                       syscallname(p, number));
           }
           db_printf(")");
   }

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