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
 104         if (symtab->private == NULL) {
 105                 if (!linker_ddb_search_symbol((caddr_t)off, &lsym, &diff)) {
 106                         *diffp = (db_expr_t)diff;
 107                         return ((c_db_sym_t)lsym);
 108                 }
 109                 return (NULL);
 110         }
 111
 112         diff = ~0UL;
 113         match = NULL;
 114         for (sym = (Elf_Sym*)symtab->start; (char*)sym < symtab->end; sym++) {
 115                 if (sym->st_name == 0 || sym->st_shndx == SHN_UNDEF)
 116                         continue;
 117                 if (off < sym->st_value)
 118                         continue;
 119                 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
 120                     ELF_ST_TYPE(sym->st_info) != STT_FUNC &&
 121                     ELF_ST_TYPE(sym->st_info) != STT_NOTYPE)
 122                         continue;
 123                 if ((off - sym->st_value) > diff)
 124                         continue;
 125                 if ((off - sym->st_value) < diff) {
 126                         diff = off - sym->st_value;
 127                         match = sym;
 128                 } else {
 129                         if (match == NULL)
 130                                 match = sym;
 131                         else if (ELF_ST_BIND(match->st_info) == STB_LOCAL &&
 132                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 133                                 match = sym;
 134                 }
 135                 if (diff == 0) {
 136                         if (strat == DB_STGY_PROC &&
 137                             ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 138                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 139                                 break;
 140                         if (strat == DB_STGY_ANY &&
 141                             ELF_ST_BIND(sym->st_info) != STB_LOCAL)
 142                                 break;
 143                 }
 144         }
 145
 146         *diffp = (match == NULL) ? off : diff;
 147         return ((c_db_sym_t)match);
 148 }
 149
 150 bool
 151 X_db_sym_numargs(db_symtab_t *symtab, c_db_sym_t sym, int *nargp,
 152     char **argp)
 153 {
 154         return (false);
 155 }
 156
 157 void
 158 X_db_symbol_values(db_symtab_t *symtab, c_db_sym_t sym, const char **namep,
 159     db_expr_t *valp)
 160 {
 161         linker_symval_t lval;
 162
 163         if (symtab->private == NULL) {
 164                 linker_ddb_symbol_values((c_linker_sym_t)sym, &lval);
 165                 if (namep != NULL)
 166                         *namep = (const char*)lval.name;
 167                 if (valp != NULL)
 168                         *valp = (db_expr_t)lval.value;
 169         } else {
 170                 if (namep != NULL)
 171                         *namep = (const char *)symtab->private +
 172                             ((const Elf_Sym *)sym)->st_name;
 173                 if (valp != NULL)
 174                         *valp = (db_expr_t)((const Elf_Sym *)sym)->st_value;
 175         }
 176 }
 177
 178 int
 179 db_fetch_ksymtab(vm_offset_t ksym_start, vm_offset_t ksym_end)
 180 {
 181         Elf_Size strsz;
 182
 183         if (ksym_end > ksym_start && ksym_start != 0) {
 184                 ksymtab = ksym_start;
 185                 ksymtab_size = *(Elf_Size*)ksymtab;
 186                 ksymtab += sizeof(Elf_Size);
 187                 kstrtab = ksymtab + ksymtab_size;
 188                 strsz = *(Elf_Size*)kstrtab;
 189                 kstrtab += sizeof(Elf_Size);
 190                 if (kstrtab + strsz > ksym_end) {
 191                         /* Sizes doesn't match, unset everything. */
 192                         ksymtab = ksymtab_size = kstrtab = 0;
 193                 }
 194         }
 195
 196         if (ksymtab == 0 || ksymtab_size == 0 || kstrtab == 0)
 197                 return (-1);
 198
 199         return (0);
 200 }
 201
 202 static int
 203 db_init(void)
 204 {
 205
 206         db_command_init();
 207
 208         if (ksymtab != 0 && kstrtab != 0 && ksymtab_size != 0) {
 209                 db_add_symbol_table((char *)ksymtab,
 210                     (char *)(ksymtab + ksymtab_size), "elf", (char *)kstrtab);
 211         }
 212         db_add_symbol_table(NULL, NULL, "kld", NULL);
 213         return (1);     /* We're the default debugger. */
 214 }
 215
 216 static int
 217 db_trap(int type, int code)
 218 {
 219         jmp_buf jb;
 220         void *prev_jb;
 221         bool bkpt, watchpt;
 222         const char *why;
 223
 224         /*
 225          * Don't handle the trap if the console is unavailable (i.e. it
 226          * is in graphics mode).
 227          */
 228         if (cnunavailable())
 229                 return (0);
 230
 231         if (db_stop_at_pc(type, code, &bkpt, &watchpt)) {
 232                 if (db_inst_count) {
 233                         db_printf("After %d instructions (%d loads, %d stores),\n",
 234                             db_inst_count, db_load_count, db_store_count);
 235                 }
 236                 prev_jb = kdb_jmpbuf(jb);
 237                 if (setjmp(jb) == 0) {
 238                         db_dot = PC_REGS();
 239                         db_print_thread();
 240                         if (bkpt)
 241                                 db_printf("Breakpoint at\t");
 242                         else if (watchpt)
 243                                 db_printf("Watchpoint at\t");
 244                         else
 245                                 db_printf("Stopped at\t");
 246                         db_print_loc_and_inst(db_dot);
 247                 }
 248                 why = kdb_why;
 249                 db_script_kdbenter(why != KDB_WHY_UNSET ? why : "unknown");
 250                 db_command_loop();
 251                 (void)kdb_jmpbuf(prev_jb);
 252         }
 253
 254         db_restart_at_pc(watchpt);
 255
 256         return (1);
 257 }
 258
 259 static void
 260 db_trace_self_wrapper(void)
 261 {
 262         jmp_buf jb;
 263         void *prev_jb;
 264
 265         prev_jb = kdb_jmpbuf(jb);
 266         if (setjmp(jb) == 0)
 267                 db_trace_self();
 268         (void)kdb_jmpbuf(prev_jb);
 269 }
 270
 271 static void
 272 db_trace_thread_wrapper(struct thread *td)
 273 {
 274         jmp_buf jb;
 275         void *prev_jb;
 276
 277         prev_jb = kdb_jmpbuf(jb);
 278         if (setjmp(jb) == 0)
 279                 db_trace_thread(td, -1);
 280         (void)kdb_jmpbuf(prev_jb);
 281 }