db_main.c

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    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 }

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FreeBSD/Linux Kernel Cross Reference sys/ddb/db_main.c

FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_main.c