FreeBSD/Linux Kernel Cross Reference
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 struct db_private {
52 char* strtab;
53 vm_offset_t relbase;
54 };
55 typedef struct db_private *db_private_t;
56
57 #define DB_PRIVATE(x) ((db_private_t)(x->private))
58
59 SYSCTL_NODE(_debug, OID_AUTO, ddb, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
60 "DDB settings");
61
62 static dbbe_init_f db_init;
63 static dbbe_trap_f db_trap;
64 static dbbe_trace_f db_trace_self_wrapper;
65 static dbbe_trace_thread_f db_trace_thread_wrapper;
66
67 KDB_BACKEND(ddb, db_init, db_trace_self_wrapper, db_trace_thread_wrapper,
68 db_trap);
69
70 /*
71 * Symbols can be loaded by specifying the exact addresses of
72 * the symtab and strtab in memory. This is used when loaded from
73 * boot loaders different than the native one (like Xen).
74 */
75 vm_offset_t ksymtab, kstrtab, ksymtab_size, ksymtab_relbase;
76 static struct db_private ksymtab_private;
77
78 bool
79 X_db_line_at_pc(db_symtab_t *symtab, c_db_sym_t sym, char **file, int *line,
80 db_expr_t off)
81 {
82 return (false);
83 }
84
85 c_db_sym_t
86 X_db_lookup(db_symtab_t *symtab, const char *symbol)
87 {
88 c_linker_sym_t lsym;
89 Elf_Sym *sym;
90
91 if (symtab->private == NULL) {
92 return ((c_db_sym_t)((!linker_ddb_lookup(symbol, &lsym))
93 ? lsym : NULL));
94 } else {
95 sym = (Elf_Sym *)symtab->start;
96 while ((char *)sym < symtab->end) {
97 if (sym->st_name != 0 &&
98 !strcmp(DB_PRIVATE(symtab)->strtab +
99 sym->st_name, symbol))
100 return ((c_db_sym_t)sym);
101 sym++;
102 }
103 }
104 return (NULL);
105 }
106
107 c_db_sym_t
108 X_db_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strat,
109 db_expr_t *diffp)
110 {
111 c_linker_sym_t lsym;
112 Elf_Sym *sym, *match;
113 unsigned long diff;
114 db_addr_t stoffs = off;
115
116 if (symtab->private == NULL) {
117 if (!linker_ddb_search_symbol((caddr_t)off, &lsym, &diff)) {
118 *diffp = (db_expr_t)diff;
119 return ((c_db_sym_t)lsym);
120 }
121 return (NULL);
122 }
123 else
124 stoffs -= DB_PRIVATE(symtab)->relbase;
125
126 diff = ~0UL;
127 match = NULL;
128 for (sym = (Elf_Sym*)symtab->start; (char*)sym < symtab->end; sym++) {
129 if (sym->st_name == 0 || sym->st_shndx == SHN_UNDEF)
130 continue;
131 if (stoffs < sym->st_value)
132 continue;
133 if (ELF_ST_TYPE(sym->st_info) != STT_OBJECT &&
134 ELF_ST_TYPE(sym->st_info) != STT_FUNC &&
135 ELF_ST_TYPE(sym->st_info) != STT_NOTYPE)
136 continue;
137 if ((stoffs - sym->st_value) > diff)
138 continue;
139 if ((stoffs - sym->st_value) < diff) {
140 diff = stoffs - sym->st_value;
141 match = sym;
142 } else {
143 if (match == NULL)
144 match = sym;
145 else if (ELF_ST_BIND(match->st_info) == STB_LOCAL &&
146 ELF_ST_BIND(sym->st_info) != STB_LOCAL)
147 match = sym;
148 }
149 if (diff == 0) {
150 if (strat == DB_STGY_PROC &&
151 ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
152 ELF_ST_BIND(sym->st_info) != STB_LOCAL)
153 break;
154 if (strat == DB_STGY_ANY &&
155 ELF_ST_BIND(sym->st_info) != STB_LOCAL)
156 break;
157 }
158 }
159
160 *diffp = (match == NULL) ? off : diff;
161 return ((c_db_sym_t)match);
162 }
163
164 bool
165 X_db_sym_numargs(db_symtab_t *symtab, c_db_sym_t sym, int *nargp,
166 char **argp)
167 {
168 return (false);
169 }
170
171 void
172 X_db_symbol_values(db_symtab_t *symtab, c_db_sym_t sym, const char **namep,
173 db_expr_t *valp)
174 {
175 linker_symval_t lval;
176
177 if (symtab->private == NULL) {
178 linker_ddb_symbol_values((c_linker_sym_t)sym, &lval);
179 if (namep != NULL)
180 *namep = (const char*)lval.name;
181 if (valp != NULL)
182 *valp = (db_expr_t)lval.value;
183 } else {
184 if (namep != NULL)
185 *namep = (const char *)DB_PRIVATE(symtab)->strtab +
186 ((const Elf_Sym *)sym)->st_name;
187 if (valp != NULL)
188 *valp = (db_expr_t)((const Elf_Sym *)sym)->st_value +
189 DB_PRIVATE(symtab)->relbase;
190 }
191 }
192
193 int
194 db_fetch_ksymtab(vm_offset_t ksym_start, vm_offset_t ksym_end,
195 vm_offset_t relbase)
196 {
197 Elf_Size strsz;
198
199 if (ksym_end > ksym_start && ksym_start != 0) {
200 ksymtab = ksym_start;
201 ksymtab_size = *(Elf_Size*)ksymtab;
202 ksymtab += sizeof(Elf_Size);
203 kstrtab = ksymtab + ksymtab_size;
204 strsz = *(Elf_Size*)kstrtab;
205 kstrtab += sizeof(Elf_Size);
206 ksymtab_relbase = relbase;
207 if (kstrtab + strsz > ksym_end) {
208 /* Sizes doesn't match, unset everything. */
209 ksymtab = ksymtab_size = kstrtab = ksymtab_relbase
210 = 0;
211 }
212 }
213
214 if (ksymtab == 0 || ksymtab_size == 0 || kstrtab == 0)
215 return (-1);
216
217 return (0);
218 }
219
220 static int
221 db_init(void)
222 {
223
224 db_command_init();
225
226 if (ksymtab != 0 && kstrtab != 0 && ksymtab_size != 0) {
227 ksymtab_private.strtab = (char *)kstrtab;
228 ksymtab_private.relbase = ksymtab_relbase;
229 db_add_symbol_table((char *)ksymtab,
230 (char *)(ksymtab + ksymtab_size), "elf", (char *)&ksymtab_private);
231 }
232 db_add_symbol_table(NULL, NULL, "kld", NULL);
233 return (1); /* We're the default debugger. */
234 }
235
236 static int
237 db_trap(int type, int code)
238 {
239 jmp_buf jb;
240 void *prev_jb;
241 bool bkpt, watchpt;
242 const char *why;
243
244 /*
245 * Don't handle the trap if the console is unavailable (i.e. it
246 * is in graphics mode).
247 */
248 if (cnunavailable())
249 return (0);
250
251 if (db_stop_at_pc(type, code, &bkpt, &watchpt)) {
252 if (db_inst_count) {
253 db_printf("After %d instructions (%d loads, %d stores),\n",
254 db_inst_count, db_load_count, db_store_count);
255 }
256 prev_jb = kdb_jmpbuf(jb);
257 if (setjmp(jb) == 0) {
258 db_dot = PC_REGS();
259 db_print_thread();
260 if (bkpt)
261 db_printf("Breakpoint at\t");
262 else if (watchpt)
263 db_printf("Watchpoint at\t");
264 else
265 db_printf("Stopped at\t");
266 db_print_loc_and_inst(db_dot);
267 }
268 why = kdb_why;
269 db_script_kdbenter(why != KDB_WHY_UNSET ? why : "unknown");
270 db_command_loop();
271 (void)kdb_jmpbuf(prev_jb);
272 }
273
274 db_restart_at_pc(watchpt);
275
276 return (1);
277 }
278
279 static void
280 db_trace_self_wrapper(void)
281 {
282 jmp_buf jb;
283 void *prev_jb;
284
285 prev_jb = kdb_jmpbuf(jb);
286 if (setjmp(jb) == 0)
287 db_trace_self();
288 (void)kdb_jmpbuf(prev_jb);
289 }
290
291 static void
292 db_trace_thread_wrapper(struct thread *td)
293 {
294 jmp_buf jb;
295 void *prev_jb;
296
297 prev_jb = kdb_jmpbuf(jb);
298 if (setjmp(jb) == 0)
299 db_trace_thread(td, -1);
300 (void)kdb_jmpbuf(prev_jb);
301 }
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