1 /* $NetBSD: mdreloc.c,v 1.38 2025/04/16 17:51:01 riastradh Exp $ */
2
3 /*
4 * Copyright 1996 John D. Polstra.
5 * Copyright 1996 Matt Thomas <matt@3am-software.com>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by John Polstra.
19 * 4. The name of the author may not be used to endorse or promote products
20 * derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 #ifndef lint
36 __RCSID("$NetBSD: mdreloc.c,v 1.38 2025/04/16 17:51:01 riastradh Exp $");
37 #endif /* not lint */
38
39 /*
40 * SuperH ELF relocations.
41 *
42 * Reference:
43 *
44 * [RM0197] SH-4 generic and C specific application binary interface
45 * https://www.st.com/resource/en/reference_manual/rm0197-sh4-generic-and-c-specific-application-binary-interface-stmicroelectronics.pdf
46 */
47
48 #include <sys/types.h>
49 #include <sys/tls.h>
50
51 #include "debug.h"
52 #include "rtld.h"
53
54 void _rtld_bind_start(void);
55 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
56 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
57 static inline int _rtld_relocate_plt_object(const Obj_Entry *,
58 const Elf_Rela *, Elf_Addr *);
59
60 void
_rtld_setup_pltgot(const Obj_Entry * obj)61 _rtld_setup_pltgot(const Obj_Entry *obj)
62 {
63 obj->pltgot[1] = (Elf_Addr) obj;
64 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
65 }
66
67 void
_rtld_relocate_nonplt_self(Elf_Dyn * dynp,Elf_Addr relocbase)68 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
69 {
70 const Elf_Rela *rela = 0, *relalim;
71 Elf_Addr relasz = 0;
72 Elf_Addr *where;
73
74 for (; dynp->d_tag != DT_NULL; dynp++) {
75 switch (dynp->d_tag) {
76 case DT_RELA:
77 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
78 break;
79 case DT_RELASZ:
80 relasz = dynp->d_un.d_val;
81 break;
82 }
83 }
84 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
85 for (; rela < relalim; rela++) {
86 where = (Elf_Addr *)(relocbase + rela->r_offset);
87 *where = (Elf_Addr)(relocbase + rela->r_addend);
88 }
89 }
90
91 int
_rtld_relocate_nonplt_objects(Obj_Entry * obj)92 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
93 {
94 const Elf_Rela *rela;
95 const Elf_Sym *def = NULL;
96 const Obj_Entry *defobj = NULL;
97 unsigned long last_symnum = ULONG_MAX;
98
99 for (rela = obj->rela; rela < obj->relalim; rela++) {
100 Elf_Addr *where;
101 Elf_Addr tmp;
102 unsigned long symnum;
103
104 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
105
106 switch (ELF_R_TYPE(rela->r_info)) {
107 case R_TYPE(GOT32):
108 case R_TYPE(REL32):
109 case R_TYPE(DIR32):
110 case R_TYPE(GLOB_DAT):
111 case R_TYPE(TLS_DTPOFF32):
112 case R_TYPE(TLS_DTPMOD32):
113 case R_TYPE(TLS_TPOFF32):
114 symnum = ELF_R_SYM(rela->r_info);
115 if (last_symnum != symnum) {
116 last_symnum = symnum;
117 def = _rtld_find_symdef(symnum, obj, &defobj,
118 false);
119 if (def == NULL)
120 return -1;
121 }
122 break;
123 default:
124 break;
125 }
126
127 switch (ELF_R_TYPE(rela->r_info)) {
128 case R_TYPE(NONE):
129 break;
130
131 #if 1 /* XXX should not occur */
132 case R_TYPE(GOT32):
133 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
134 rela->r_addend);
135 if (*where != tmp)
136 *where = tmp;
137 rdbg(("GOT32 %s in %s --> %p in %s",
138 obj->strtab + obj->symtab[symnum].st_name,
139 obj->path, (void *)*where, defobj->path));
140 break;
141
142 case R_TYPE(REL32):
143 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
144 rela->r_addend) - (Elf_Addr)where;
145 if (*where != tmp)
146 *where = tmp;
147 rdbg(("PC32 %s in %s --> %p in %s",
148 obj->strtab + obj->symtab[symnum].st_name,
149 obj->path, (void *)*where, defobj->path));
150 break;
151 #endif
152
153 case R_TYPE(DIR32):
154 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
155 rela->r_addend);
156 if (*where != tmp)
157 *where = tmp;
158 rdbg(("32 %s in %s --> %p in %s",
159 obj->strtab + obj->symtab[symnum].st_name,
160 obj->path, (void *)*where, defobj->path));
161 break;
162
163 case R_TYPE(GLOB_DAT):
164 tmp = (Elf_Addr)(defobj->relocbase + def->st_value) +
165 rela->r_addend;
166 if (*where != tmp)
167 *where = tmp;
168 rdbg(("GLOB_DAT %s in %s --> %p in %s",
169 obj->strtab + obj->symtab[symnum].st_name,
170 obj->path, (void *)*where, defobj->path));
171 break;
172
173 case R_TYPE(RELATIVE):
174 if (rela->r_addend)
175 *where = (Elf_Addr)obj->relocbase + rela->r_addend;
176 else
177 *where += (Elf_Addr)obj->relocbase;
178 rdbg(("RELATIVE in %s --> %p", obj->path,
179 (void *)*where));
180 break;
181
182 case R_TYPE(COPY):
183 /*
184 * These are deferred until all other relocations have
185 * been done. All we do here is make sure that the
186 * COPY relocation is not in a shared library. They
187 * are allowed only in executable files.
188 */
189 if (obj->isdynamic) {
190 _rtld_error(
191 "%s: Unexpected R_COPY relocation in shared library",
192 obj->path);
193 return -1;
194 }
195 rdbg(("COPY (avoid in main)"));
196 break;
197
198 case R_TYPE(TLS_DTPOFF32):
199 *where = (Elf_Addr)(def->st_value);
200
201 rdbg(("TLS_DTPOFF32 %s in %s --> %p",
202 obj->strtab + obj->symtab[symnum].st_name,
203 obj->path, (void *)*where));
204
205 break;
206 case R_TYPE(TLS_DTPMOD32):
207 *where = (Elf_Addr)(defobj->tlsindex);
208
209 rdbg(("TLS_DTPMOD32 %s in %s --> %p",
210 obj->strtab + obj->symtab[symnum].st_name,
211 obj->path, (void *)*where));
212
213 break;
214
215 case R_TYPE(TLS_TPOFF32):
216 if (!defobj->tls_static &&
217 _rtld_tls_offset_allocate(__UNCONST(defobj)))
218 return -1;
219
220 *where = (Elf_Addr)def->st_value +
221 rela->r_addend + defobj->tlsoffset +
222 sizeof(struct tls_tcb);
223
224 rdbg(("TLS_TPOFF32 %s in %s --> %p",
225 obj->strtab + obj->symtab[symnum].st_name,
226 obj->path, (void *)*where));
227 break;
228
229 default:
230 rdbg(("sym = %lu, type = %lu, offset = %p, "
231 "addend = %p, contents = %p, symbol = %s",
232 (u_long)ELF_R_SYM(rela->r_info),
233 (u_long)ELF_R_TYPE(rela->r_info),
234 (void *)rela->r_offset, (void *)rela->r_addend,
235 (void *)*where,
236 obj->strtab + obj->symtab[symnum].st_name));
237 _rtld_error("%s: Unsupported relocation type %ld "
238 "in non-PLT relocations",
239 obj->path, (u_long) ELF_R_TYPE(rela->r_info));
240 return -1;
241 }
242 }
243 return 0;
244 }
245
246 int
_rtld_relocate_plt_lazy(Obj_Entry * obj)247 _rtld_relocate_plt_lazy(Obj_Entry *obj)
248 {
249 const Elf_Rela *rela;
250
251 if (!obj->relocbase)
252 return 0;
253
254 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
255 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
256
257 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
258
259 /* Just relocate the GOT slots pointing into the PLT */
260 *where += (Elf_Addr)obj->relocbase;
261 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
262 }
263
264 return 0;
265 }
266
267 caddr_t
_rtld_bind(const Obj_Entry * obj,Elf_Word reloff)268 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
269 {
270 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
271 Elf_Addr new_value;
272 int err;
273
274 new_value = 0; /* XXX gcc */
275
276 _rtld_shared_enter();
277 err = _rtld_relocate_plt_object(obj, rela, &new_value);
278 if (err)
279 _rtld_die();
280 _rtld_shared_exit();
281
282 return (caddr_t)new_value;
283 }
284
285 int
_rtld_relocate_plt_objects(const Obj_Entry * obj)286 _rtld_relocate_plt_objects(const Obj_Entry *obj)
287 {
288 const Elf_Rela *rela = obj->pltrela;
289
290 for (; rela < obj->pltrelalim; rela++)
291 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
292 return -1;
293
294 return 0;
295 }
296
297 static inline int
_rtld_relocate_plt_object(const Obj_Entry * obj,const Elf_Rela * rela,Elf_Addr * tp)298 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
299 {
300 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
301 Elf_Addr new_value;
302 const Elf_Sym *def;
303 const Obj_Entry *defobj;
304 unsigned long info = rela->r_info;
305
306 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
307
308 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
309 if (__predict_false(def == NULL))
310 return -1;
311 if (__predict_false(def == &_rtld_sym_zero))
312 return 0;
313
314 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
315 if (tp == NULL)
316 return 0;
317 new_value = _rtld_resolve_ifunc(defobj, def);
318 } else {
319 new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
320 }
321 rdbg(("bind now/fixup in %s --> old=%p new=%p",
322 defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
323 if (*where != new_value)
324 *where = new_value;
325
326 if (tp)
327 *tp = new_value;
328
329 return 0;
330 }
331