sys/ddb/db_main.c

   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 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  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 SYSCTL_NODE(_debug, OID_AUTO, ddb, CTLFLAG_RW, 0, "DDB settings");
  50
  51 static dbbe_init_f db_init;
  52 static dbbe_trap_f db_trap;
  53 static dbbe_trace_f db_trace_self_wrapper;
  54 static dbbe_trace_thread_f db_trace_thread_wrapper;
  55
  56 KDB_BACKEND(ddb, db_init, db_trace_self_wrapper, db_trace_thread_wrapper,
  57     db_trap);
  58
  59 /*
  60  * Symbols can be loaded by specifying the exact addresses of
  61  * the symtab and strtab in memory. This is used when loaded from
  62  * boot loaders different than the native one (like Xen).
  63  */
  64 vm_offset_t ksymtab, kstrtab, ksymtab_size;
  65
  66 bool
  67 X_db_line_at_pc(db_symtab_t *symtab, c_db_sym_t sym, char **file, int *line,
  68     db_expr_t off)
  69 {
  70         return (false);
  71 }
  72
  73 c_db_sym_t
  74 X_db_lookup(db_symtab_t *symtab, const char *symbol)
  75 {
  76         c_linker_sym_t lsym;
  77         Elf_Sym *sym;
  78
  79         if (symtab->private == NULL) {
  80                 return ((c_db_sym_t)((!linker_ddb_lookup(symbol, &lsym))
  81                         ? lsym : NULL));
  82         } else {
  83                 sym = (Elf_Sym *)symtab->start;
  84                 while ((char *)sym < symtab->end) {
  85                         if (sym->st_name != 0 &&
  86                             !strcmp(symtab->private + sym->st_name, symbol))
  87                                 return ((c_db_sym_t)sym);
  88                         sym++;
  89                 }
  90         }
  91         return (NULL);
  92 }
  93
  94 c_db_sym_t
  95 X_db_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strat,
  96     db_expr_t *diffp)
  97 {
  98         c_linker_sym_t lsym;
  99         Elf_Sym *sym, *match;
 100         unsigned long diff;
 101
 102         if (symtab->private == NULL) {
 103                 if (!linker_ddb_search_symbol((caddr_t)off, &lsym, &diff)) {
 104                         *diffp = (db_expr_t)diff;
 105                         return ((c_db_sym_t)lsym);
 106                 }
 107                 return (NULL);
 108         }
 109
 110         diff = ~0UL;
 111         match = NULL;
 112         for (sym = (Elf_Sym*)symtab->start; (char*)sym < symtab->end; sym++) {
 113                 if (sym->st_name == 0 || sym->st_shndx == SHN_UNDEF)
 114                         continue;
 115                 if (off < sym->st_value)
 116                         continue;
 117                 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
 118                     ELF_ST_TYPE(sym->st_info) != STT_FUNC &&
 119                     ELF_ST_TYPE(sym->st_info) != STT_NOTYPE)
 120                         continue;
 121                 if ((off - sym->st_value) > diff)
 122                         continue;
 123                 if ((off - sym->st_value) < diff) {
 124                         diff = off - sym->st_value;
 125                         match = sym;
 126                 } else {
 127                         if (match == NULL)
 128                                 match = sym;
 129                         else if (ELF_ST_BIND(match->st_info) == STB_LOCAL &&
 130                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 131                                 match = sym;
 132                 }
 133                 if (diff == 0) {
 134                         if (strat == DB_STGY_PROC &&
 135                             ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 136                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 137                                 break;
 138                         if (strat == DB_STGY_ANY &&
 139                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 140                                 break;
 141                 }
 142         }
 143
 144         *diffp = (match == NULL) ? off : diff;
 145         return ((c_db_sym_t)match);
 146 }
 147
 148 bool
 149 X_db_sym_numargs(db_symtab_t *symtab, c_db_sym_t sym, int *nargp,
 150     char **argp)
 151 {
 152         return (false);
 153 }
 154
 155 void
 156 X_db_symbol_values(db_symtab_t *symtab, c_db_sym_t sym, const char **namep,
 157     db_expr_t *valp)
 158 {
 159         linker_symval_t lval;
 160
 161         if (symtab->private == NULL) {
 162                 linker_ddb_symbol_values((c_linker_sym_t)sym, &lval);
 163                 if (namep != NULL)
 164                         *namep = (const char*)lval.name;
 165                 if (valp != NULL)
 166                         *valp = (db_expr_t)lval.value;
 167         } else {
 168                 if (namep != NULL)
 169                         *namep = (const char *)symtab->private +
 170                             ((const Elf_Sym *)sym)->st_name;
 171                 if (valp != NULL)
 172                         *valp = (db_expr_t)((const Elf_Sym *)sym)->st_value;
 173         }
 174 }
 175
 176 int
 177 db_fetch_ksymtab(vm_offset_t ksym_start, vm_offset_t ksym_end)
 178 {
 179         Elf_Size strsz;
 180
 181         if (ksym_end > ksym_start && ksym_start != 0) {
 182                 ksymtab = ksym_start;
 183                 ksymtab_size = *(Elf_Size*)ksymtab;
 184                 ksymtab += sizeof(Elf_Size);
 185                 kstrtab = ksymtab + ksymtab_size;
 186                 strsz = *(Elf_Size*)kstrtab;
 187                 kstrtab += sizeof(Elf_Size);
 188                 if (kstrtab + strsz > ksym_end) {
 189                         /* Sizes doesn't match, unset everything. */
 190                         ksymtab = ksymtab_size = kstrtab = 0;
 191                 }
 192         }
 193
 194         if (ksymtab == 0 || ksymtab_size == 0 || kstrtab == 0)
 195                 return (-1);
 196
 197         return (0);
 198 }
 199
 200 static int
 201 db_init(void)
 202 {
 203
 204         db_command_init();
 205
 206         if (ksymtab != 0 && kstrtab != 0 && ksymtab_size != 0) {
 207                 db_add_symbol_table((char *)ksymtab,
 208                     (char *)(ksymtab + ksymtab_size), "elf", (char *)kstrtab);
 209         }
 210         db_add_symbol_table(NULL, NULL, "kld", NULL);
 211         return (1);     /* We're the default debugger. */
 212 }
 213
 214 static int
 215 db_trap(int type, int code)
 216 {
 217         jmp_buf jb;
 218         void *prev_jb;
 219         bool bkpt, watchpt;
 220         const char *why;
 221
 222         /*
 223          * Don't handle the trap if the console is unavailable (i.e. it
 224          * is in graphics mode).
 225          */
 226         if (cnunavailable())
 227                 return (0);
 228
 229         if (db_stop_at_pc(type, code, &bkpt, &watchpt)) {
 230                 if (db_inst_count) {
 231                         db_printf("After %d instructions (%d loads, %d stores),\n",
 232                             db_inst_count, db_load_count, db_store_count);
 233                 }
 234                 prev_jb = kdb_jmpbuf(jb);
 235                 if (setjmp(jb) == 0) {
 236                         db_dot = PC_REGS();
 237                         db_print_thread();
 238                         if (bkpt)
 239                                 db_printf("Breakpoint at\t");
 240                         else if (watchpt)
 241                                 db_printf("Watchpoint at\t");
 242                         else
 243                                 db_printf("Stopped at\t");
 244                         db_print_loc_and_inst(db_dot);
 245                 }
 246                 why = kdb_why;
 247                 db_script_kdbenter(why != KDB_WHY_UNSET ? why : "unknown");
 248                 db_command_loop();
 249                 (void)kdb_jmpbuf(prev_jb);
 250         }
 251
 252         db_restart_at_pc(watchpt);
 253
 254         return (1);
 255 }
 256
 257 static void
 258 db_trace_self_wrapper(void)
 259 {
 260         jmp_buf jb;
 261         void *prev_jb;
 262
 263         prev_jb = kdb_jmpbuf(jb);
 264         if (setjmp(jb) == 0)
 265                 db_trace_self();
 266         (void)kdb_jmpbuf(prev_jb);
 267 }
 268
 269 static void
 270 db_trace_thread_wrapper(struct thread *td)
 271 {
 272         jmp_buf jb;
 273         void *prev_jb;
 274
 275         prev_jb = kdb_jmpbuf(jb);
 276         if (setjmp(jb) == 0)
 277                 db_trace_thread(td, -1);
 278         (void)kdb_jmpbuf(prev_jb);
 279 }