sys/ddb/db_main.c

   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 #include <sys/cdefs.h>
  30 __FBSDID("$FreeBSD$");
  31
  32 #include <sys/param.h>
  33 #include <sys/systm.h>
  34 #include <sys/cons.h>
  35 #include <sys/linker.h>
  36 #include <sys/kdb.h>
  37 #include <sys/kernel.h>
  38 #include <sys/pcpu.h>
  39 #include <sys/proc.h>
  40 #include <sys/reboot.h>
  41 #include <sys/sysctl.h>
  42
  43 #include <machine/kdb.h>
  44 #include <machine/pcb.h>
  45 #include <machine/setjmp.h>
  46
  47 #include <ddb/ddb.h>
  48 #include <ddb/db_command.h>
  49 #include <ddb/db_sym.h>
  50
  51 struct db_private {
  52         char*           strtab;
  53         vm_offset_t     relbase;
  54 };
  55 typedef struct db_private *db_private_t;
  56
  57 #define DB_PRIVATE(x) ((db_private_t)(x->private))
  58
  59 SYSCTL_NODE(_debug, OID_AUTO, ddb, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
  60     "DDB settings");
  61
  62 static dbbe_init_f db_init;
  63 static dbbe_trap_f db_trap;
  64 static dbbe_trace_f db_trace_self_wrapper;
  65 static dbbe_trace_thread_f db_trace_thread_wrapper;
  66
  67 KDB_BACKEND(ddb, db_init, db_trace_self_wrapper, db_trace_thread_wrapper,
  68     db_trap);
  69
  70 /*
  71  * Symbols can be loaded by specifying the exact addresses of
  72  * the symtab and strtab in memory. This is used when loaded from
  73  * boot loaders different than the native one (like Xen).
  74  */
  75 vm_offset_t ksymtab, kstrtab, ksymtab_size, ksymtab_relbase;
  76 static struct db_private ksymtab_private;
  77
  78 bool
  79 X_db_line_at_pc(db_symtab_t *symtab, c_db_sym_t sym, char **file, int *line,
  80     db_expr_t off)
  81 {
  82         return (false);
  83 }
  84
  85 c_db_sym_t
  86 X_db_lookup(db_symtab_t *symtab, const char *symbol)
  87 {
  88         c_linker_sym_t lsym;
  89         Elf_Sym *sym;
  90
  91         if (symtab->private == NULL) {
  92                 return ((c_db_sym_t)((!linker_ddb_lookup(symbol, &lsym))
  93                         ? lsym : NULL));
  94         } else {
  95                 sym = (Elf_Sym *)symtab->start;
  96                 while ((char *)sym < symtab->end) {
  97                         if (sym->st_name != 0 &&
  98                             !strcmp(DB_PRIVATE(symtab)->strtab +
  99                             sym->st_name, symbol))
 100                                 return ((c_db_sym_t)sym);
 101                         sym++;
 102                 }
 103         }
 104         return (NULL);
 105 }
 106
 107 c_db_sym_t
 108 X_db_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strat,
 109     db_expr_t *diffp)
 110 {
 111         c_linker_sym_t lsym;
 112         Elf_Sym *sym, *match;
 113         unsigned long diff;
 114         db_addr_t stoffs = off;
 115
 116         if (symtab->private == NULL) {
 117                 if (!linker_ddb_search_symbol((caddr_t)off, &lsym, &diff)) {
 118                         *diffp = (db_expr_t)diff;
 119                         return ((c_db_sym_t)lsym);
 120                 }
 121                 return (NULL);
 122         }
 123         else
 124                 stoffs -= DB_PRIVATE(symtab)->relbase;
 125
 126         diff = ~0UL;
 127         match = NULL;
 128         for (sym = (Elf_Sym*)symtab->start; (char*)sym < symtab->end; sym++) {
 129                 if (sym->st_name == 0 || sym->st_shndx == SHN_UNDEF)
 130                         continue;
 131                 if (stoffs < sym->st_value)
 132                         continue;
 133                 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
 134                     ELF_ST_TYPE(sym->st_info) != STT_FUNC &&
 135                     ELF_ST_TYPE(sym->st_info) != STT_NOTYPE)
 136                         continue;
 137                 if ((stoffs - sym->st_value) > diff)
 138                         continue;
 139                 if ((stoffs - sym->st_value) < diff) {
 140                         diff = stoffs - sym->st_value;
 141                         match = sym;
 142                 } else {
 143                         if (match == NULL)
 144                                 match = sym;
 145                         else if (ELF_ST_BIND(match->st_info) == STB_LOCAL &&
 146                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 147                                 match = sym;
 148                 }
 149                 if (diff == 0) {
 150                         if (strat == DB_STGY_PROC &&
 151                             ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 152                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 153                                 break;
 154                         if (strat == DB_STGY_ANY &&
 155                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 156                                 break;
 157                 }
 158         }
 159
 160         *diffp = (match == NULL) ? off : diff;
 161         return ((c_db_sym_t)match);
 162 }
 163
 164 bool
 165 X_db_sym_numargs(db_symtab_t *symtab, c_db_sym_t sym, int *nargp,
 166     char **argp)
 167 {
 168         return (false);
 169 }
 170
 171 void
 172 X_db_symbol_values(db_symtab_t *symtab, c_db_sym_t sym, const char **namep,
 173     db_expr_t *valp)
 174 {
 175         linker_symval_t lval;
 176
 177         if (symtab->private == NULL) {
 178                 linker_ddb_symbol_values((c_linker_sym_t)sym, &lval);
 179                 if (namep != NULL)
 180                         *namep = (const char*)lval.name;
 181                 if (valp != NULL)
 182                         *valp = (db_expr_t)lval.value;
 183         } else {
 184                 if (namep != NULL)
 185                         *namep = (const char *)DB_PRIVATE(symtab)->strtab +
 186                             ((const Elf_Sym *)sym)->st_name;
 187                 if (valp != NULL)
 188                         *valp = (db_expr_t)((const Elf_Sym *)sym)->st_value +
 189                             DB_PRIVATE(symtab)->relbase;
 190         }
 191 }
 192
 193 int
 194 db_fetch_ksymtab(vm_offset_t ksym_start, vm_offset_t ksym_end,
 195     vm_offset_t relbase)
 196 {
 197         Elf_Size strsz;
 198
 199         if (ksym_end > ksym_start && ksym_start != 0) {
 200                 ksymtab = ksym_start;
 201                 ksymtab_size = *(Elf_Size*)ksymtab;
 202                 ksymtab += sizeof(Elf_Size);
 203                 kstrtab = ksymtab + ksymtab_size;
 204                 strsz = *(Elf_Size*)kstrtab;
 205                 kstrtab += sizeof(Elf_Size);
 206                 ksymtab_relbase = relbase;
 207                 if (kstrtab + strsz > ksym_end) {
 208                         /* Sizes doesn't match, unset everything. */
 209                         ksymtab = ksymtab_size = kstrtab = ksymtab_relbase
 210                             = 0;
 211                 }
 212         }
 213
 214         if (ksymtab == 0 || ksymtab_size == 0 || kstrtab == 0)
 215                 return (-1);
 216
 217         return (0);
 218 }
 219
 220 static int
 221 db_init(void)
 222 {
 223
 224         db_command_init();
 225
 226         if (ksymtab != 0 && kstrtab != 0 && ksymtab_size != 0) {
 227                 ksymtab_private.strtab = (char *)kstrtab;
 228                 ksymtab_private.relbase = ksymtab_relbase;
 229                 db_add_symbol_table((char *)ksymtab,
 230                     (char *)(ksymtab + ksymtab_size), "elf", (char *)&ksymtab_private);
 231         }
 232         db_add_symbol_table(NULL, NULL, "kld", NULL);
 233         return (1);     /* We're the default debugger. */
 234 }
 235
 236 static int
 237 db_trap(int type, int code)
 238 {
 239         jmp_buf jb;
 240         void *prev_jb;
 241         bool bkpt, watchpt;
 242         const char *why;
 243
 244         /*
 245          * Don't handle the trap if the console is unavailable (i.e. it
 246          * is in graphics mode).
 247          */
 248         if (cnunavailable())
 249                 return (0);
 250
 251         if (db_stop_at_pc(type, code, &bkpt, &watchpt)) {
 252                 if (db_inst_count) {
 253                         db_printf("After %d instructions (%d loads, %d stores),\n",
 254                             db_inst_count, db_load_count, db_store_count);
 255                 }
 256                 prev_jb = kdb_jmpbuf(jb);
 257                 if (setjmp(jb) == 0) {
 258                         db_dot = PC_REGS();
 259                         db_print_thread();
 260                         if (bkpt)
 261                                 db_printf("Breakpoint at\t");
 262                         else if (watchpt)
 263                                 db_printf("Watchpoint at\t");
 264                         else
 265                                 db_printf("Stopped at\t");
 266                         db_print_loc_and_inst(db_dot);
 267                 }
 268                 why = kdb_why;
 269                 db_script_kdbenter(why != KDB_WHY_UNSET ? why : "unknown");
 270                 db_command_loop();
 271                 (void)kdb_jmpbuf(prev_jb);
 272         }
 273
 274         db_restart_at_pc(watchpt);
 275
 276         return (1);
 277 }
 278
 279 static void
 280 db_trace_self_wrapper(void)
 281 {
 282         jmp_buf jb;
 283         void *prev_jb;
 284
 285         prev_jb = kdb_jmpbuf(jb);
 286         if (setjmp(jb) == 0)
 287                 db_trace_self();
 288         (void)kdb_jmpbuf(prev_jb);
 289 }
 290
 291 static void
 292 db_trace_thread_wrapper(struct thread *td)
 293 {
 294         jmp_buf jb;
 295         void *prev_jb;
 296
 297         prev_jb = kdb_jmpbuf(jb);
 298         if (setjmp(jb) == 0)
 299                 db_trace_thread(td, -1);
 300         (void)kdb_jmpbuf(prev_jb);
 301 }