1 /* $OpenBSD: db_elf.c,v 1.7 2006/03/13 06:23:20 jsg Exp $ */
2 /* $NetBSD: db_elf.c,v 1.13 2000/07/07 21:55:18 jhawk Exp $ */
3
4 /*-
5 * Copyright (c) 1997 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
10 * NASA Ames Research Center.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 * This product includes software developed by the NetBSD
23 * Foundation, Inc. and its contributors.
24 * 4. Neither the name of The NetBSD Foundation nor the names of its
25 * contributors may be used to endorse or promote products derived
26 * from this software without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
29 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
30 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
31 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
32 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
33 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
34 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
35 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
36 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
37 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
38 * POSSIBILITY OF SUCH DAMAGE.
39 */
40
41 #include <sys/types.h>
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/proc.h>
45 #include <sys/exec.h>
46
47 #include <machine/db_machdep.h>
48
49 #include <ddb/db_sym.h>
50 #include <ddb/db_output.h>
51 #include <ddb/db_extern.h>
52
53 #ifdef DB_ELF_SYMBOLS
54
55 #ifndef DB_ELFSIZE
56 #error Must define DB_ELFSIZE!
57 #endif
58
59 #define ELFSIZE DB_ELFSIZE
60
61 #include <sys/exec_elf.h>
62
63 static char *db_elf_find_strtab(db_symtab_t *);
64
65 #define STAB_TO_SYMSTART(stab) ((Elf_Sym *)((stab)->start))
66 #define STAB_TO_SYMEND(stab) ((Elf_Sym *)((stab)->end))
67 #define STAB_TO_EHDR(stab) ((Elf_Ehdr *)((stab)->private))
68 #define STAB_TO_SHDR(stab, e) ((Elf_Shdr *)((stab)->private + (e)->e_shoff))
69
70 boolean_t db_elf_sym_init(int, void *, void *, const char *);
71 db_sym_t db_elf_lookup(db_symtab_t *, char *);
72 db_sym_t db_elf_search_symbol(db_symtab_t *, db_addr_t,
73 db_strategy_t, db_expr_t *);
74 void db_elf_symbol_values(db_symtab_t *, db_sym_t,
75 char **, db_expr_t *);
76 boolean_t db_elf_line_at_pc(db_symtab_t *, db_sym_t,
77 char **, int *, db_expr_t);
78 boolean_t db_elf_sym_numargs(db_symtab_t *, db_sym_t, int *,
79 char **);
80 void db_elf_forall(db_symtab_t *,
81 db_forall_func_t db_forall_func, void *);
82
83 db_symformat_t db_symformat_elf = {
84 "ELF",
85 db_elf_sym_init,
86 db_elf_lookup,
87 db_elf_search_symbol,
88 db_elf_symbol_values,
89 db_elf_line_at_pc,
90 db_elf_sym_numargs,
91 db_elf_forall
92 };
93
94 /*
95 * Find the symbol table and strings; tell ddb about them.
96 *
97 * symsize: size of symbol table
98 * symtab: pointer to start of symbol table
99 * esymtab: pointer to end of string table, for checking - rounded up to
100 * integer boundry
101 */
102 boolean_t
103 db_elf_sym_init(int symsize, void *symtab, void *esymtab, const char *name)
104 {
105 Elf_Ehdr *elf;
106 Elf_Shdr *shp;
107 Elf_Sym *symp, *symtab_start, *symtab_end;
108 char *shstrtab, *strtab_start, *strtab_end;
109 int i;
110 char *errstr = "";
111
112 if (ALIGNED_POINTER(symtab, long) == 0) {
113 printf("[ %s symbol table has bad start address %p ]\n",
114 name, symtab);
115 return (FALSE);
116 }
117
118 symtab_start = symtab_end = NULL;
119 strtab_start = strtab_end = NULL;
120
121 /*
122 * The format of the symbols loaded by the boot program is:
123 *
124 * Elf exec header
125 * first section header
126 * . . .
127 * . . .
128 * last section header
129 * first symbol or string table section
130 * . . .
131 * . . .
132 * last symbol or string table section
133 */
134
135 /*
136 * Validate the Elf header.
137 */
138 elf = (Elf_Ehdr *)symtab;
139 if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 ||
140 elf->e_ident[EI_CLASS] != ELFCLASS) {
141 errstr = "bad magic";
142 goto badheader;
143 }
144
145 if (elf->e_machine != ELF_TARG_MACH) {
146 errstr = "bad e_machine";
147 goto badheader;
148 }
149
150 /*
151 * Find the section header string table (.shstrtab), and look up
152 * the symbol table (.symtab) and string table (.strtab) via their
153 * names in shstrtab, rather than by table type.
154 * This works in the presence of multiple string tables, such as
155 * stabs data found when booting bsd.gdb.
156 */
157 shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff);
158 shstrtab = (char *)symtab + shp[elf->e_shstrndx].sh_offset;
159 for (i = 0; i < elf->e_shnum; i++) {
160 if (shp[i].sh_type == SHT_SYMTAB) {
161 int j;
162
163 if (shp[i].sh_offset == 0)
164 continue;
165 symtab_start = (Elf_Sym *)((char *)symtab +
166 shp[i].sh_offset);
167 symtab_end = (Elf_Sym *)((char *)symtab +
168 shp[i].sh_offset + shp[i].sh_size);
169 j = shp[i].sh_link;
170 if (shp[j].sh_offset == 0)
171 continue;
172 strtab_start = (char *)symtab + shp[j].sh_offset;
173 strtab_end = (char *)symtab + shp[j].sh_offset +
174 shp[j].sh_size;
175 break;
176 }
177
178 /*
179 * This is the old way of doing things.
180 * XXX - verify that it's not needed.
181 */
182 if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) {
183 strtab_start = (char *)symtab + shp[i].sh_offset;
184 strtab_end = (char *)symtab + shp[i].sh_offset +
185 shp[i].sh_size;
186 } else if (strcmp(".symtab", shstrtab+shp[i].sh_name) == 0) {
187 symtab_start = (Elf_Sym *)((char *)symtab +
188 shp[i].sh_offset);
189 symtab_end = (Elf_Sym *)((char *)symtab +
190 shp[i].sh_offset + shp[i].sh_size);
191 }
192 }
193
194 /*
195 * Now, sanity check the symbols against the string table.
196 */
197 if (symtab_start == NULL || strtab_start == NULL ||
198 ALIGNED_POINTER(symtab_start, long) == 0 ||
199 ALIGNED_POINTER(strtab_start, long) == 0) {
200 errstr = "symtab unaligned";
201 goto badheader;
202 }
203 for (symp = symtab_start; symp < symtab_end; symp++)
204 if (symp->st_name + strtab_start > strtab_end) {
205 errstr = "symtab corrupted";
206 goto badheader;
207 }
208
209 /*
210 * Link the symbol table into the debugger.
211 */
212 if (db_add_symbol_table((char *)symtab_start,
213 (char *)symtab_end, name, (char *)symtab) != -1) {
214 printf("[ using %lu bytes of %s ELF symbol table ]\n",
215 (u_long)roundup(((char *)esymtab - (char *)symtab),
216 sizeof(u_long)), name);
217 return (TRUE);
218 }
219
220 return (FALSE);
221
222 badheader:
223 printf("[ %s ELF symbol table not valid: %s ]\n", name, errstr);
224 return (FALSE);
225 }
226
227 /*
228 * Internal helper function - return a pointer to the string table
229 * for the current symbol table.
230 */
231 static char *
232 db_elf_find_strtab(db_symtab_t *stab)
233 {
234 Elf_Ehdr *elf = STAB_TO_EHDR(stab);
235 Elf_Shdr *shp = STAB_TO_SHDR(stab, elf);
236 char *shstrtab;
237 int i;
238
239 shstrtab = (char *)elf + shp[elf->e_shstrndx].sh_offset;
240 for (i = 0; i < elf->e_shnum; i++) {
241 if (shp[i].sh_type == SHT_SYMTAB)
242 return ((char *)elf + shp[shp[i].sh_link].sh_offset);
243 if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0)
244 return ((char *)elf + shp[i].sh_offset);
245 }
246
247 return (NULL);
248 }
249
250 /*
251 * Lookup the symbol with the given name.
252 */
253 db_sym_t
254 db_elf_lookup(db_symtab_t *stab, char *symstr)
255 {
256 Elf_Sym *symp, *symtab_start, *symtab_end;
257 char *strtab;
258
259 symtab_start = STAB_TO_SYMSTART(stab);
260 symtab_end = STAB_TO_SYMEND(stab);
261
262 strtab = db_elf_find_strtab(stab);
263 if (strtab == NULL)
264 return ((db_sym_t)0);
265
266 for (symp = symtab_start; symp < symtab_end; symp++) {
267 if (symp->st_name != 0 &&
268 db_eqname(strtab + symp->st_name, symstr, 0))
269 return ((db_sym_t)symp);
270 }
271
272 return ((db_sym_t)0);
273 }
274
275 /*
276 * Search for the symbol with the given address (matching within the
277 * provided threshold).
278 */
279 db_sym_t
280 db_elf_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strategy,
281 db_expr_t *diffp)
282 {
283 Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end;
284 db_expr_t diff = *diffp;
285
286 symtab_start = STAB_TO_SYMSTART(symtab);
287 symtab_end = STAB_TO_SYMEND(symtab);
288
289 rsymp = NULL;
290
291 for (symp = symtab_start; symp < symtab_end; symp++) {
292 if (symp->st_name == 0)
293 continue;
294 #if 0
295 /* This prevents me from seeing anythin in locore.s -- eeh */
296 if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object &&
297 ELF_SYM_TYPE(symp->st_info) != Elf_estt_func)
298 continue;
299 #endif
300
301 if (off >= symp->st_value) {
302 if ((off - symp->st_value) < diff) {
303 diff = off - symp->st_value;
304 rsymp = symp;
305 if (diff == 0) {
306 if (strategy == DB_STGY_PROC &&
307 ELFDEFNNAME(ST_TYPE)(symp->st_info)
308 == STT_FUNC &&
309 ELFDEFNNAME(ST_BIND)(symp->st_info)
310 != STB_LOCAL)
311 break;
312 if (strategy == DB_STGY_ANY &&
313 ELFDEFNNAME(ST_BIND)(symp->st_info)
314 != STB_LOCAL)
315 break;
316 }
317 } else if ((off - symp->st_value) == diff) {
318 if (rsymp == NULL)
319 rsymp = symp;
320 else if (ELFDEFNNAME(ST_BIND)(rsymp->st_info)
321 == STB_LOCAL &&
322 ELFDEFNNAME(ST_BIND)(symp->st_info)
323 != STB_LOCAL) {
324 /* pick the external symbol */
325 rsymp = symp;
326 }
327 }
328 }
329 }
330
331 if (rsymp == NULL)
332 *diffp = off;
333 else
334 *diffp = diff;
335
336 return ((db_sym_t)rsymp);
337 }
338
339 /*
340 * Return the name and value for a symbol.
341 */
342 void
343 db_elf_symbol_values(db_symtab_t *symtab, db_sym_t sym, char **namep,
344 db_expr_t *valuep)
345 {
346 Elf_Sym *symp = (Elf_Sym *)sym;
347 char *strtab;
348
349 if (namep) {
350 strtab = db_elf_find_strtab(symtab);
351 if (strtab == NULL)
352 *namep = NULL;
353 else
354 *namep = strtab + symp->st_name;
355 }
356
357 if (valuep)
358 *valuep = symp->st_value;
359 }
360
361 /*
362 * Return the file and line number of the current program counter
363 * if we can find the appropriate debugging symbol.
364 */
365 boolean_t
366 db_elf_line_at_pc(db_symtab_t *symtab, db_sym_t cursym, char **filename,
367 int *linenum, db_expr_t off)
368 {
369
370 /*
371 * XXX We don't support this (yet).
372 */
373 return (FALSE);
374 }
375
376 /*
377 * Returns the number of arguments to a function and their
378 * names if we can find the appropriate debugging symbol.
379 */
380 boolean_t
381 db_elf_sym_numargs(db_symtab_t *symtab, db_sym_t cursym, int *nargp,
382 char **argnamep)
383 {
384
385 /*
386 * XXX We don't support this (yet).
387 */
388 return (FALSE);
389 }
390
391 void
392 db_elf_forall(db_symtab_t *stab, db_forall_func_t db_forall_func, void *arg)
393 {
394 char *strtab;
395 static char suffix[2];
396 Elf_Sym *symp, *symtab_start, *symtab_end;
397
398 symtab_start = STAB_TO_SYMSTART(stab);
399 symtab_end = STAB_TO_SYMEND(stab);
400
401 strtab = db_elf_find_strtab(stab);
402 if (strtab == NULL)
403 return;
404
405 for (symp = symtab_start; symp < symtab_end; symp++)
406 if (symp->st_name != 0) {
407 suffix[1] = '\0';
408 switch (ELFDEFNNAME(ST_TYPE)(symp->st_info)) {
409 case STT_OBJECT:
410 suffix[0] = '+';
411 break;
412 case STT_FUNC:
413 suffix[0] = '*';
414 break;
415 case STT_SECTION:
416 suffix[0] = '&';
417 break;
418 case STT_FILE:
419 suffix[0] = '/';
420 break;
421 default:
422 suffix[0] = '\0';
423 }
424 (*db_forall_func)(stab, (db_sym_t)symp,
425 strtab + symp->st_name, suffix, 0, arg);
426 }
427 return;
428 }
429 #endif /* DB_ELF_SYMBOLS */