FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_elf.c
1 /* $FreeBSD$ */
2 /* $NetBSD: db_elf.c,v 1.4 1998/05/03 18:49:54 thorpej 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 #if defined(__ELF__) && defined(__alpha__)
42
43 #include "opt_ddb.h"
44
45 #include <sys/types.h>
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/proc.h>
49
50 #include <machine/db_machdep.h>
51
52 #include <ddb/db_sym.h>
53 #include <ddb/db_output.h>
54
55 #include <machine/elf.h>
56
57 static char *db_elf_find_strtab __P((db_symtab_t *));
58
59 #define STAB_TO_SYMSTART(stab) ((Elf_Sym *)((stab)->start))
60 #define STAB_TO_SYMEND(stab) ((Elf_Sym *)((stab)->end))
61 #define STAB_TO_EHDR(stab) ((Elf_Ehdr *)((stab)->private))
62 #define STAB_TO_SHDR(stab, e) ((Elf_Shdr *)((stab)->private + (e)->e_shoff))
63
64 void X_db_sym_init(void *symtab, void *esymtab, char *name);
65
66 /*
67 * Find the symbol table and strings; tell ddb about them.
68 */
69 void
70 X_db_sym_init(symtab, esymtab, name)
71 void *symtab; /* pointer to start of symbol table */
72 void *esymtab; /* pointer to end of string table,
73 for checking - rounded up to integer
74 boundary */
75 char *name;
76 {
77 Elf_Ehdr *elf;
78 Elf_Shdr *shp;
79 Elf_Sym *symp, *symtab_start, *symtab_end;
80 char *strtab_start, *strtab_end;
81 int i;
82
83 if (ALIGNED_POINTER(symtab, long) == 0) {
84 printf("DDB: bad symbol table start address %p\n", symtab);
85 return;
86 }
87
88 symtab_start = symtab_end = NULL;
89 strtab_start = strtab_end = NULL;
90
91 /*
92 * The format of the symbols loaded by the boot program is:
93 *
94 * Elf exec header
95 * first section header
96 * . . .
97 * . . .
98 * last section header
99 * first symbol or string table section
100 * . . .
101 * . . .
102 * last symbol or string table section
103 */
104
105 /*
106 * Validate the Elf header.
107 */
108 elf = (Elf_Ehdr *)symtab;
109 if (elf->e_ident[EI_MAG0] != ELFMAG0
110 || elf->e_ident[EI_MAG1] != ELFMAG1
111 || elf->e_ident[EI_MAG2] != ELFMAG2
112 || elf->e_ident[EI_MAG3] != ELFMAG3)
113 goto badheader;
114
115 if (!ELF_MACHINE_OK(elf->e_machine))
116 goto badheader;
117
118 /*
119 * We need to avoid the section header string table (small string
120 * table which names the sections). We do this by assuming that
121 * the following two conditions will be true:
122 *
123 * (1) .shstrtab will be smaller than one page.
124 * (2) .strtab will be larger than one page.
125 *
126 * When we encounter what we think is the .shstrtab, we change
127 * its section type Elf_sht_null so that it will be ignored
128 * later.
129 */
130 shp = (Elf_Shdr *)((char*)symtab + elf->e_shoff);
131 for (i = 0; i < elf->e_shnum; i++) {
132 if (shp[i].sh_addr || i == elf->e_shstrndx)
133 continue;
134 switch (shp[i].sh_type) {
135 case SHT_STRTAB:
136 if (shp[i].sh_size < PAGE_SIZE) {
137 shp[i].sh_type = SHT_NULL;
138 continue;
139 }
140 if (strtab_start != NULL)
141 goto multiple_strtab;
142 strtab_start = (char *)symtab + shp[i].sh_offset;
143 strtab_end = (char *)symtab + shp[i].sh_offset +
144 shp[i].sh_size;
145 break;
146
147 case SHT_SYMTAB:
148 if (symtab_start != NULL)
149 goto multiple_symtab;
150 symtab_start = (Elf_Sym *)((char*)symtab + shp[i].sh_offset);
151 symtab_end = (Elf_Sym *)((char*)symtab + shp[i].sh_offset +
152 shp[i].sh_size);
153 break;
154
155 default:
156 /* Ignore all other sections. */
157 break;
158 }
159 }
160
161 /*
162 * Now, sanity check the symbols against the string table.
163 */
164 if (symtab_start == NULL || strtab_start == NULL ||
165 ALIGNED_POINTER(symtab_start, long) == 0 ||
166 ALIGNED_POINTER(strtab_start, long) == 0)
167 goto badheader;
168 for (symp = symtab_start; symp < symtab_end; symp++)
169 if (symp->st_name + strtab_start > strtab_end)
170 goto badheader;
171
172 /*
173 * Link the symbol table into the debugger.
174 */
175 db_add_symbol_table((char *)symtab_start,
176 (char *)symtab_end, name, (char *)symtab);
177 printf("[ preserving %lu bytes of %s symbol table ]\n",
178 (u_long)roundup(((char*)esymtab - (char*)symtab), sizeof(u_long)), name);
179 return;
180
181 badheader:
182 printf("[ %s symbol table not valid ]\n", name);
183 return;
184
185 multiple_strtab:
186 printf("[ %s has multiple string tables ]\n", name);
187 return;
188
189 multiple_symtab:
190 printf("[ %s has multiple symbol tables ]\n", name);
191 return;
192 }
193
194 /*
195 * Internal helper function - return a pointer to the string table
196 * for the current symbol table.
197 */
198 static char *
199 db_elf_find_strtab(stab)
200 db_symtab_t *stab;
201 {
202 Elf_Ehdr *elf = STAB_TO_EHDR(stab);
203 Elf_Shdr *shp = STAB_TO_SHDR(stab, elf);
204 int i;
205
206 for (i = 0; i < elf->e_shnum; i++) {
207 if (shp[i].sh_type == SHT_STRTAB
208 && !shp[i].sh_addr && i != elf->e_shstrndx)
209 return (stab->private + shp[i].sh_offset);
210 }
211
212 return (NULL);
213 }
214
215 /*
216 * Lookup the symbol with the given name.
217 */
218 db_sym_t
219 X_db_lookup(stab, symstr)
220 db_symtab_t *stab;
221 char *symstr;
222 {
223 Elf_Sym *symp, *symtab_start, *symtab_end;
224 char *strtab;
225
226 symtab_start = STAB_TO_SYMSTART(stab);
227 symtab_end = STAB_TO_SYMEND(stab);
228
229 strtab = db_elf_find_strtab(stab);
230 if (strtab == NULL)
231 return ((db_sym_t)0);
232
233 for (symp = symtab_start; symp < symtab_end; symp++) {
234 if (symp->st_name != 0 &&
235 db_eqname(strtab + symp->st_name, symstr, 0))
236 return ((db_sym_t)symp);
237 }
238
239 return ((db_sym_t)0);
240 }
241
242 /*
243 * Search for the symbol with the given address (matching within the
244 * provided threshold).
245 */
246 db_sym_t
247 X_db_search_symbol(symtab, off, strategy, diffp)
248 db_symtab_t *symtab;
249 db_addr_t off;
250 db_strategy_t strategy;
251 db_expr_t *diffp; /* in/out */
252 {
253 Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end;
254 db_expr_t diff = *diffp;
255
256 symtab_start = STAB_TO_SYMSTART(symtab);
257 symtab_end = STAB_TO_SYMEND(symtab);
258
259 rsymp = NULL;
260
261 for (symp = symtab_start; symp < symtab_end; symp++) {
262 if (symp->st_name == 0)
263 continue;
264 if (ELF_ST_TYPE(symp->st_info) != STT_OBJECT &&
265 ELF_ST_TYPE(symp->st_info) != STT_FUNC)
266 continue;
267
268 if (off >= symp->st_value) {
269 if ((off - symp->st_value) < diff) {
270 diff = off - symp->st_value;
271 rsymp = symp;
272 if (diff == 0) {
273 if (strategy == DB_STGY_PROC &&
274 ELF_ST_TYPE(symp->st_info) ==
275 STT_FUNC &&
276 ELF_ST_BIND(symp->st_info) !=
277 STB_LOCAL)
278 break;
279 if (strategy == DB_STGY_ANY &&
280 ELF_ST_BIND(symp->st_info) !=
281 STB_LOCAL)
282 break;
283 }
284 } else if ((off - symp->st_value) == diff) {
285 if (rsymp == NULL)
286 rsymp = symp;
287 else if (ELF_ST_BIND(rsymp->st_info) ==
288 STB_LOCAL &&
289 ELF_ST_BIND(symp->st_info) !=
290 STB_LOCAL) {
291 /* pick the external symbol */
292 rsymp = symp;
293 }
294 }
295 }
296 }
297
298 if (rsymp == NULL)
299 *diffp = off;
300 else
301 *diffp = diff;
302
303 return ((db_sym_t)rsymp);
304 }
305
306 /*
307 * Return the name and value for a symbol.
308 */
309 void
310 X_db_symbol_values(symtab, sym, namep, valuep)
311 db_symtab_t *symtab;
312 db_sym_t sym;
313 char **namep;
314 db_expr_t *valuep;
315 {
316 Elf_Sym *symp = (Elf_Sym *)sym;
317 char *strtab;
318
319 if (namep) {
320 strtab = db_elf_find_strtab(symtab);
321 if (strtab == NULL)
322 *namep = NULL;
323 else
324 *namep = strtab + symp->st_name;
325 }
326
327 if (valuep)
328 *valuep = symp->st_value;
329 }
330
331 /*
332 * Return the file and line number of the current program counter
333 * if we can find the appropriate debugging symbol.
334 */
335 boolean_t
336 X_db_line_at_pc(symtab, cursym, filename, linenum, off)
337 db_symtab_t *symtab;
338 db_sym_t cursym;
339 char **filename;
340 int *linenum;
341 db_expr_t off;
342 {
343
344 /*
345 * XXX We don't support this (yet).
346 */
347 return (FALSE);
348 }
349
350 /*
351 * Returns the number of arguments to a function and their
352 * names if we can find the appropriate debugging symbol.
353 */
354 boolean_t
355 X_db_sym_numargs(symtab, cursym, nargp, argnamep)
356 db_symtab_t *symtab;
357 db_sym_t cursym;
358 int *nargp;
359 char **argnamep;
360 {
361
362 /*
363 * XXX We don't support this (yet).
364 */
365 return (FALSE);
366 }
367
368 /*
369 * Initialization routine for Elf files.
370 */
371 extern void *ksym_start, *ksym_end;
372
373 void
374 kdb_init(void)
375 {
376
377 if (ksym_end > ksym_start)
378 X_db_sym_init(ksym_start, ksym_end, "kernel");
379 }
380
381 #endif
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