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