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