1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
24 */
25
26 #include <stdio.h>
27 #include <string.h>
28 #include <link.h>
29 #include <debug.h>
30 #include "msg.h"
31 #include "_libld.h"
32
33 /*
34 * Determine whether a (COMDAT) group has already been encountered. If so,
35 * indicate that the group descriptor has an overriding group (gd_oisc). This
36 * indication triggers the ld_place_section() to discard this group, while the
37 * gd_oisc information provides for complete diagnostics of the override.
38 * Otherwise, this is the first occurrence of this group, therefore the group
39 * descriptor is saved for future comparisons.
40 */
41 static uintptr_t
gpavl_loaded(Ofl_desc * ofl,Group_desc * gdp)42 gpavl_loaded(Ofl_desc *ofl, Group_desc *gdp)
43 {
44 Isd_node isd, *isdp;
45 avl_tree_t *avlt;
46 avl_index_t where;
47
48 /*
49 * Create a groups avl tree if required.
50 */
51 if ((avlt = ofl->ofl_groups) == NULL) {
52 if ((avlt = libld_calloc(1, sizeof (avl_tree_t))) == NULL)
53 return (S_ERROR);
54 avl_create(avlt, isdavl_compare, sizeof (Isd_node),
55 SGSOFFSETOF(Isd_node, isd_avl));
56 ofl->ofl_groups = avlt;
57 }
58
59 /*
60 * An SHT_GROUP section is identified by the name of its signature
61 * symbol rather than section name. Although the section names are
62 * often unique, this is not required, and some compilers set it to
63 * a generic name like ".group".
64 */
65 isd.isd_name = gdp->gd_name;
66 isd.isd_hash = sgs_str_hash(isd.isd_name);
67
68 if ((isdp = avl_find(avlt, &isd, &where)) != NULL) {
69 gdp->gd_oisc = isdp->isd_isp;
70 return (1);
71 }
72
73 /*
74 * This is a new group - so keep it.
75 */
76 if ((isdp = libld_calloc(1, sizeof (Isd_node))) == NULL)
77 return (S_ERROR);
78
79 isdp->isd_name = isd.isd_name;
80 isdp->isd_hash = isd.isd_hash;
81 isdp->isd_isp = gdp->gd_isc;
82
83 avl_insert(avlt, isdp, where);
84 return (0);
85 }
86
87 Group_desc *
ld_get_group(Ofl_desc * ofl,Is_desc * isp)88 ld_get_group(Ofl_desc *ofl, Is_desc *isp)
89 {
90 Ifl_desc *ifl = isp->is_file;
91 uint_t scnndx = isp->is_scnndx;
92 Group_desc *gdp;
93 Aliste idx;
94
95 /*
96 * Scan the GROUP sections associated with this file to find the
97 * matching group section.
98 */
99 for (ALIST_TRAVERSE(ifl->ifl_groups, idx, gdp)) {
100 size_t ndx;
101 Word *data;
102
103 if (isp->is_shdr->sh_type == SHT_GROUP) {
104 if (isp->is_scnndx == gdp->gd_isc->is_scnndx)
105 return (gdp);
106 continue;
107 }
108
109 data = gdp->gd_data;
110 for (ndx = 1; ndx < gdp->gd_cnt; ndx++) {
111 if (data[ndx] == scnndx)
112 return (gdp);
113 }
114 }
115
116 ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_ELF_NOGROUPSECT),
117 ifl->ifl_name, EC_WORD(isp->is_scnndx), isp->is_name);
118 return (NULL);
119 }
120
121 /*
122 * When creating a .debug_macro section, in an attempt to make certain DWARF
123 * macro information shareable, the GNU compiler must construct group sections
124 * with a repeatable signature symbol while nevertheless having no actual
125 * symbol to refer to (because it relates to macros).
126 *
127 * We use this as yet another way to clue ourselves in that sloppy relocation
128 * will likely be required.
129 *
130 * The format of these gensym'd names is:
131 * wm<offset size>.<encoded path name>.<lineno>.<32byte hash>
132 * Where the encoded file name may be absent.
133 */
134 static boolean_t
is_header_gensym(const char * name)135 is_header_gensym(const char *name)
136 {
137 const char *c = NULL;
138 size_t len = strlen(name);
139
140 /* No room for leader, hash, and periods */
141 if (len < 37)
142 return (B_FALSE);
143
144 if ((strncmp(name, "wm4.", 4) != 0) &&
145 strncmp(name, "wm8.", 4) != 0)
146 return (B_FALSE);
147
148 c = &name[len - 33];
149 if (*c++ != '.')
150 return (B_FALSE);
151
152 for (; *c != '\0'; c++) {
153 if (!(((*c >= 'a') && (*c <= 'f')) ||
154 ((*c >= '0') && (*c <= '9')))) {
155 return (B_FALSE);
156 }
157 }
158
159 return (B_TRUE);
160 }
161
162 uintptr_t
ld_group_process(Is_desc * gisc,Ofl_desc * ofl)163 ld_group_process(Is_desc *gisc, Ofl_desc *ofl)
164 {
165 Ifl_desc *gifl = gisc->is_file;
166 Shdr *sshdr, *gshdr = gisc->is_shdr;
167 Word *new_data = NULL;
168 Shdr *new_shdr = NULL;
169 Is_desc *isc;
170 Sym *sym;
171 const char *str;
172 Group_desc gd;
173 size_t ndx;
174 int gnu_stt_section;
175
176 /*
177 * Confirm that the sh_link points to a valid section.
178 */
179 if ((gshdr->sh_link == SHN_UNDEF) ||
180 (gshdr->sh_link >= gifl->ifl_shnum) ||
181 ((isc = gifl->ifl_isdesc[gshdr->sh_link]) == NULL)) {
182 ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHLINK),
183 gifl->ifl_name, EC_WORD(gisc->is_scnndx),
184 gisc->is_name, EC_XWORD(gshdr->sh_link));
185 return (0);
186 }
187 if (gshdr->sh_entsize == 0) {
188 ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHENTSIZE),
189 gifl->ifl_name, EC_WORD(gisc->is_scnndx), gisc->is_name,
190 EC_XWORD(gshdr->sh_entsize));
191 return (0);
192 }
193
194 /*
195 * Get the associated symbol table. Sanity check the sh_info field
196 * (which points to the signature symbol table entry) against the size
197 * of the symbol table.
198 */
199 sshdr = isc->is_shdr;
200 sym = (Sym *)isc->is_indata->d_buf;
201
202 if ((sshdr->sh_info == SHN_UNDEF) ||
203 (gshdr->sh_info >= (Word)(sshdr->sh_size / sshdr->sh_entsize)) ||
204 ((isc = gifl->ifl_isdesc[sshdr->sh_link]) == NULL)) {
205 ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHINFO),
206 gifl->ifl_name, EC_WORD(gisc->is_scnndx), gisc->is_name,
207 EC_XWORD(gshdr->sh_info));
208 return (0);
209 }
210
211 sym += gshdr->sh_info;
212
213 /*
214 * Get the symbol name from the associated string table.
215 */
216 str = (char *)isc->is_indata->d_buf;
217 str += sym->st_name;
218
219 /*
220 * The GNU assembler can use section symbols as the signature symbol
221 * as described by this comment in the gold linker (found via google):
222 *
223 * It seems that some versions of gas will create a section group
224 * associated with a section symbol, and then fail to give a name
225 * to the section symbol. In such a case, use the name of the
226 * section.
227 *
228 * In order to support such objects, we do the same.
229 */
230 gnu_stt_section = ((sym->st_name == 0) || (*str == '\0')) &&
231 (ELF_ST_TYPE(sym->st_info) == STT_SECTION);
232 if (gnu_stt_section)
233 str = gisc->is_name;
234
235
236 /*
237 * Generate a group descriptor.
238 */
239 gd.gd_isc = gisc;
240 gd.gd_oisc = NULL;
241 gd.gd_name = str;
242 gd.gd_data = gisc->is_indata->d_buf;
243 gd.gd_cnt = gisc->is_indata->d_size / sizeof (Word);
244
245 /*
246 * If the signature symbol is a name generated by the GNU compiler to
247 * refer to a header, we need sloppy relocation.
248 */
249 if (is_header_gensym(str)) {
250 if ((ofl->ofl_flags1 & FLG_OF1_NRLXREL) == 0)
251 ofl->ofl_flags1 |= FLG_OF1_RLXREL;
252 DBG_CALL(Dbg_sec_gnu_comdat(ofl->ofl_lml, gisc, TRUE,
253 (ofl->ofl_flags1 & FLG_OF1_RLXREL) != 0));
254 }
255
256 /*
257 * Validate the section indices within the group. If this is a COMDAT
258 * group, mark each section as COMDAT.
259 */
260 for (ndx = (gd.gd_cnt - 1); ndx >= 1; ndx--) {
261 Word gndx = gd.gd_data[ndx];
262
263 if ((gndx == 0) || (gndx >= gifl->ifl_shnum)) {
264 ld_eprintf(ofl, ERR_FATAL,
265 MSG_INTL(MSG_GRP_INVALNDX), gifl->ifl_name,
266 EC_WORD(gisc->is_scnndx), gisc->is_name, ndx, gndx);
267 return (0);
268 }
269
270 /*
271 * If we reach here the group was valid but has been damaged
272 * by FLG_OF_STRIP. That is, this section in the group exists
273 * but was ignored during input processing.
274 *
275 * If this entry is NULL, remove it from the group. You might
276 * think we can make consuming code careful to be aware that
277 * entries in a group may not exist, but if we are linking a
278 * relocatable object (-r -s), the group must survive, and a
279 * bogus entry must not be written out.
280 */
281 if (gifl->ifl_isdesc[gndx] == NULL) {
282 /*
283 * We need to allocate new data for the group and the
284 * shdr, the existing data is mapped from the file.
285 */
286 if (new_data == NULL) {
287 if ((new_data = libld_calloc(sizeof (Word),
288 gd.gd_cnt)) == NULL)
289 return (S_ERROR);
290
291 /*
292 * Copy up the whole thing, we'll shrink it in
293 * a moment.
294 */
295 memcpy(new_data, gd.gd_data,
296 sizeof (Word) * gd.gd_cnt);
297 gisc->is_indata->d_buf = gd.gd_data = new_data;
298
299 new_shdr = libld_malloc(sizeof (Shdr));
300 if (new_shdr == NULL)
301 return (S_ERROR);
302
303 memcpy(new_shdr, gisc->is_shdr, sizeof (Shdr));
304 gisc->is_shdr = new_shdr;
305 }
306
307 /* If there're entries after us, copy them down */
308 if (ndx < (gd.gd_cnt - 1)) {
309 memmove(&gd.gd_data[ndx], &gd.gd_data[ndx + 1],
310 (gd.gd_cnt - (ndx + 1)) * sizeof (Word));
311 }
312
313 gisc->is_indata->d_size -= sizeof (Word);
314 gisc->is_shdr->sh_size -= sizeof (Word);
315 gd.gd_cnt -= 1;
316 continue;
317 }
318
319 if (gd.gd_data[0] & GRP_COMDAT)
320 gifl->ifl_isdesc[gndx]->is_flags |= FLG_IS_COMDAT;
321 }
322
323 /*
324 * If we're left with only one item in the group -- the header --
325 * discard it.
326 */
327 if (gd.gd_cnt == 1)
328 gisc->is_flags |= FLG_IS_DISCARD;
329
330 /*
331 * If this is a COMDAT group, determine whether this group has already
332 * been encountered, or whether this is the first instance of the group.
333 */
334 if ((gd.gd_data[0] & GRP_COMDAT) &&
335 (gpavl_loaded(ofl, &gd) == S_ERROR))
336 return (S_ERROR);
337
338 /*
339 * Associate the group descriptor with this input file.
340 */
341 if (alist_append(&(gifl->ifl_groups), &gd, sizeof (Group_desc),
342 AL_CNT_IFL_GROUPS) == NULL)
343 return (S_ERROR);
344
345 return (1);
346 }
347