1 /* $NetBSD: mdreloc.c,v 1.37 2025/04/18 12:56:47 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 /*
35 * m68k ELF relocations.
36 *
37 * References:
38 *
39 * [M68KSYSVABI] System V Application Binary Interface: Motorola
40 * 68000 Processor Family Supplement, 1990, AT&T.
41 * https://people.debian.org/~glaubitz/m68k-sysv-abi.pdf
42 * https://web.archive.org/web/20250317195959/https://people.debian.org/~glaubitz/m68k-sysv-abi.pdf
43 */
44
45 #include <sys/cdefs.h>
46 #ifndef lint
47 __RCSID("$NetBSD: mdreloc.c,v 1.37 2025/04/18 12:56:47 riastradh Exp $");
48 #endif /* not lint */
49
50 #include <sys/types.h>
51
52 #include "debug.h"
53 #include "rtld.h"
54
55 #include <machine/lwp_private.h>
56
57 void _rtld_bind_start(void);
58 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
59 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
60 static inline int _rtld_relocate_plt_object(const Obj_Entry *,
61 const Elf_Rela *, Elf_Addr *);
62
63
64 void
_rtld_setup_pltgot(const Obj_Entry * obj)65 _rtld_setup_pltgot(const Obj_Entry *obj)
66 {
67 obj->pltgot[1] = (Elf_Addr) obj;
68 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
69 }
70
71 void
_rtld_relocate_nonplt_self(Elf_Dyn * dynp,Elf_Addr relocbase)72 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
73 {
74 const Elf_Rela *rela = 0, *relalim;
75 Elf_Addr relasz = 0;
76 Elf_Addr *where;
77
78 for (; dynp->d_tag != DT_NULL; dynp++) {
79 switch (dynp->d_tag) {
80 case DT_RELA:
81 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
82 break;
83 case DT_RELASZ:
84 relasz = dynp->d_un.d_val;
85 break;
86 }
87 }
88 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
89 for (; rela < relalim; rela++) {
90 where = (Elf_Addr *)(relocbase + rela->r_offset);
91 *where += (Elf_Addr)relocbase;
92 }
93 }
94
95 int
_rtld_relocate_nonplt_objects(Obj_Entry * obj)96 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
97 {
98 const Elf_Rela *rela;
99 const Elf_Sym *def = NULL;
100 const Obj_Entry *defobj = NULL;
101 unsigned long last_symnum = ULONG_MAX;
102
103 for (rela = obj->rela; rela < obj->relalim; rela++) {
104 Elf_Addr *where;
105 Elf_Addr tmp;
106 unsigned long symnum;
107
108 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
109
110 switch (ELF_R_TYPE(rela->r_info)) {
111 case R_TYPE(PC32):
112 case R_TYPE(GOT32):
113 case R_TYPE(32):
114 case R_TYPE(GLOB_DAT):
115 case R_TYPE(TLS_DTPMOD32):
116 case R_TYPE(TLS_DTPREL32):
117 case R_TYPE(TLS_TPREL32):
118 symnum = ELF_R_SYM(rela->r_info);
119 if (last_symnum != symnum) {
120 last_symnum = symnum;
121 def = _rtld_find_symdef(symnum, obj, &defobj,
122 false);
123 if (def == NULL)
124 return -1;
125 }
126 break;
127 default:
128 break;
129 }
130
131 switch (ELF_R_TYPE(rela->r_info)) {
132 case R_TYPE(NONE):
133 break;
134
135 #if 1 /* XXX should not occur */
136 case R_TYPE(PC32):
137 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
138 rela->r_addend) - (Elf_Addr)where;
139 if (*where != tmp)
140 *where = tmp;
141 rdbg(("PC32 %s in %s --> %p in %s",
142 obj->strtab + obj->symtab[symnum].st_name,
143 obj->path, (void *)*where, defobj->path));
144 break;
145
146 case R_TYPE(GOT32):
147 #endif
148 case R_TYPE(32):
149 case R_TYPE(GLOB_DAT):
150 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
151 rela->r_addend);
152 if (*where != tmp)
153 *where = tmp;
154 rdbg(("32/GLOB_DAT %s in %s --> %p in %s",
155 obj->strtab + obj->symtab[symnum].st_name,
156 obj->path, (void *)*where, defobj->path));
157 break;
158
159 case R_TYPE(RELATIVE):
160 *where += (Elf_Addr)obj->relocbase;
161 rdbg(("RELATIVE in %s --> %p", obj->path,
162 (void *)*where));
163 break;
164
165 case R_TYPE(COPY):
166 /*
167 * These are deferred until all other relocations have
168 * been done. All we do here is make sure that the
169 * COPY relocation is not in a shared library. They
170 * are allowed only in executable files.
171 */
172 if (obj->isdynamic) {
173 _rtld_error(
174 "%s: Unexpected R_COPY relocation in shared library",
175 obj->path);
176 return -1;
177 }
178 rdbg(("COPY (avoid in main)"));
179 break;
180
181 case R_TYPE(TLS_DTPMOD32):
182 *where = (Elf_Addr)defobj->tlsindex;
183 rdbg(("DTPMOD32 %s in %s --> %p in %s",
184 obj->strtab + obj->symtab[symnum].st_name,
185 obj->path, (void *)*where, defobj->path));
186 break;
187
188 case R_TYPE(TLS_DTPREL32):
189 *where = (Elf_Addr)(def->st_value + rela->r_addend
190 - TLS_DTV_OFFSET);
191 rdbg(("DTPREL32 %s in %s --> %p in %s",
192 obj->strtab + obj->symtab[symnum].st_name,
193 obj->path, (void *)*where, defobj->path));
194 break;
195
196 case R_TYPE(TLS_TPREL32):
197 if (!defobj->tls_static &&
198 _rtld_tls_offset_allocate(__UNCONST(defobj)))
199 return -1;
200
201 *where = (Elf_Addr)(def->st_value + rela->r_addend
202 + defobj->tlsoffset - TLS_TP_OFFSET);
203 rdbg(("TPREL32 %s in %s --> %p in %s",
204 obj->strtab + obj->symtab[symnum].st_name,
205 obj->path, (void *)*where, defobj->path));
206 break;
207
208 default:
209 rdbg(("sym = %lu, type = %lu, offset = %p, "
210 "addend = %p, contents = %p, symbol = %s",
211 (u_long)ELF_R_SYM(rela->r_info),
212 (u_long)ELF_R_TYPE(rela->r_info),
213 (void *)rela->r_offset, (void *)rela->r_addend,
214 (void *)*where,
215 obj->strtab + obj->symtab[symnum].st_name));
216 _rtld_error("%s: Unsupported relocation type %ld "
217 "in non-PLT relocations",
218 obj->path, (u_long) ELF_R_TYPE(rela->r_info));
219 return -1;
220 }
221 }
222 return 0;
223 }
224
225 int
_rtld_relocate_plt_lazy(Obj_Entry * obj)226 _rtld_relocate_plt_lazy(Obj_Entry *obj)
227 {
228 const Elf_Rela *rela;
229
230 if (!obj->relocbase)
231 return 0;
232
233 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
234 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
235
236 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
237
238 /* Just relocate the GOT slots pointing into the PLT */
239 *where += (Elf_Addr)obj->relocbase;
240 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
241 }
242
243 return 0;
244 }
245
246 static inline int
_rtld_relocate_plt_object(const Obj_Entry * obj,const Elf_Rela * rela,Elf_Addr * tp)247 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela,
248 Elf_Addr *tp)
249 {
250 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
251 Elf_Addr new_value;
252 const Elf_Sym *def;
253 const Obj_Entry *defobj;
254 unsigned long info = rela->r_info;
255
256 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
257
258 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
259 if (__predict_false(def == NULL))
260 return -1;
261 if (__predict_false(def == &_rtld_sym_zero))
262 return 0;
263
264 assert(rela->r_addend == 0);
265 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
266 if (tp == NULL)
267 return 0;
268 new_value = _rtld_resolve_ifunc(defobj, def);
269 } else {
270 new_value = (Elf_Addr)(defobj->relocbase + def->st_value +
271 rela->r_addend);
272 }
273 rdbg(("bind now/fixup in %s --> old=%p new=%p",
274 defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
275 if (*where != new_value)
276 *where = new_value;
277
278 if (tp)
279 *tp = new_value - rela->r_addend;
280
281 return 0;
282 }
283
284 caddr_t
_rtld_bind(const Obj_Entry * obj,Elf_Word reloff)285 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
286 {
287 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
288 Elf_Addr result;
289 int err;
290
291 result = 0; /* XXX gcc */
292
293 _rtld_shared_enter();
294 err = _rtld_relocate_plt_object(obj, rela, &result);
295 if (err)
296 _rtld_die();
297 _rtld_shared_exit();
298
299 return (caddr_t)result;
300 }
301
302 int
_rtld_relocate_plt_objects(const Obj_Entry * obj)303 _rtld_relocate_plt_objects(const Obj_Entry *obj)
304 {
305 const Elf_Rela *rela;
306
307 for (rela = obj->pltrela; rela < obj->pltrelalim; rela++)
308 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
309 return -1;
310
311 return 0;
312 }
313