1 /* $NetBSD: mdreloc.c,v 1.38 2014/08/25 20:40:52 joerg Exp $ */
2
3 #include <sys/cdefs.h>
4 #ifndef lint
5 __RCSID("$NetBSD: mdreloc.c,v 1.38 2014/08/25 20:40:52 joerg Exp $");
6 #endif /* not lint */
7
8 #include <sys/types.h>
9 #include <string.h>
10
11 #include "debug.h"
12 #include "rtld.h"
13
14 void _rtld_bind_start(void);
15 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
16 caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
17
18 void
_rtld_setup_pltgot(const Obj_Entry * obj)19 _rtld_setup_pltgot(const Obj_Entry *obj)
20 {
21 obj->pltgot[1] = (Elf_Addr) obj;
22 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
23 }
24
25 void
_rtld_relocate_nonplt_self(Elf_Dyn * dynp,Elf_Addr relocbase)26 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
27 {
28 const Elf_Rel *rel = 0, *rellim;
29 Elf_Addr relsz = 0;
30 Elf_Addr *where;
31
32 for (; dynp->d_tag != DT_NULL; dynp++) {
33 switch (dynp->d_tag) {
34 case DT_REL:
35 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
36 break;
37 case DT_RELSZ:
38 relsz = dynp->d_un.d_val;
39 break;
40 }
41 }
42 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz);
43 for (; rel < rellim; rel++) {
44 where = (Elf_Addr *)(relocbase + rel->r_offset);
45 *where += (Elf_Addr)relocbase;
46 }
47 }
48
49 /*
50 * It is possible for the compiler to emit relocations for unaligned data.
51 * We handle this situation with these inlines.
52 */
53 #define RELOC_ALIGNED_P(x) \
54 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
55
56 static inline Elf_Addr
load_ptr(void * where)57 load_ptr(void *where)
58 {
59 Elf_Addr res;
60
61 memcpy(&res, where, sizeof(res));
62
63 return (res);
64 }
65
66 static inline void
store_ptr(void * where,Elf_Addr val)67 store_ptr(void *where, Elf_Addr val)
68 {
69
70 memcpy(where, &val, sizeof(val));
71 }
72
73 int
_rtld_relocate_nonplt_objects(Obj_Entry * obj)74 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
75 {
76 const Elf_Rel *rel;
77
78 for (rel = obj->rel; rel < obj->rellim; rel++) {
79 Elf_Addr *where;
80 const Elf_Sym *def;
81 const Obj_Entry *defobj;
82 Elf_Addr tmp;
83 unsigned long symnum;
84
85 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
86 symnum = ELF_R_SYM(rel->r_info);
87
88 switch (ELF_R_TYPE(rel->r_info)) {
89 case R_TYPE(NONE):
90 break;
91
92 #if 1 /* XXX should not occur */
93 case R_TYPE(PC24): { /* word32 S - P + A */
94 Elf32_Sword addend;
95
96 /*
97 * Extract addend and sign-extend if needed.
98 */
99 addend = *where;
100 if (addend & 0x00800000)
101 addend |= 0xff000000;
102
103 def = _rtld_find_symdef(symnum, obj, &defobj, false);
104 if (def == NULL)
105 return -1;
106 tmp = (Elf_Addr)obj->relocbase + def->st_value
107 - (Elf_Addr)where + (addend << 2);
108 if ((tmp & 0xfe000000) != 0xfe000000 &&
109 (tmp & 0xfe000000) != 0) {
110 _rtld_error(
111 "%s: R_ARM_PC24 relocation @ %p to %s failed "
112 "(displacement %ld (%#lx) out of range)",
113 obj->path, where,
114 obj->strtab + obj->symtab[symnum].st_name,
115 (long) tmp, (long) tmp);
116 return -1;
117 }
118 tmp >>= 2;
119 *where = (*where & 0xff000000) | (tmp & 0x00ffffff);
120 rdbg(("PC24 %s in %s --> %p @ %p in %s",
121 obj->strtab + obj->symtab[symnum].st_name,
122 obj->path, (void *)*where, where, defobj->path));
123 break;
124 }
125 #endif
126
127 case R_TYPE(ABS32): /* word32 B + S + A */
128 case R_TYPE(GLOB_DAT): /* word32 B + S */
129 def = _rtld_find_symdef(symnum, obj, &defobj, false);
130 if (def == NULL)
131 return -1;
132 if (__predict_true(RELOC_ALIGNED_P(where))) {
133 tmp = *where + (Elf_Addr)defobj->relocbase +
134 def->st_value;
135 /* Set the Thumb bit, if needed. */
136 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC)
137 tmp |= 1;
138 *where = tmp;
139 } else {
140 tmp = load_ptr(where) +
141 (Elf_Addr)defobj->relocbase +
142 def->st_value;
143 /* Set the Thumb bit, if needed. */
144 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC)
145 tmp |= 1;
146 store_ptr(where, tmp);
147 }
148 rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s",
149 obj->strtab + obj->symtab[symnum].st_name,
150 obj->path, (void *)tmp, where, defobj->path));
151 break;
152
153 case R_TYPE(RELATIVE): /* word32 B + A */
154 if (__predict_true(RELOC_ALIGNED_P(where))) {
155 tmp = *where + (Elf_Addr)obj->relocbase;
156 *where = tmp;
157 } else {
158 tmp = load_ptr(where) +
159 (Elf_Addr)obj->relocbase;
160 store_ptr(where, tmp);
161 }
162 rdbg(("RELATIVE in %s --> %p", obj->path,
163 (void *)tmp));
164 break;
165
166 case R_TYPE(COPY):
167 /*
168 * These are deferred until all other relocations have
169 * been done. All we do here is make sure that the
170 * COPY relocation is not in a shared library. They
171 * are allowed only in executable files.
172 */
173 if (obj->isdynamic) {
174 _rtld_error(
175 "%s: Unexpected R_COPY relocation in shared library",
176 obj->path);
177 return -1;
178 }
179 rdbg(("COPY (avoid in main)"));
180 break;
181
182 #if defined(__minix) && defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
183 case R_TYPE(TLS_DTPOFF32):
184 def = _rtld_find_symdef(symnum, obj, &defobj, false);
185 if (def == NULL)
186 return -1;
187
188 tmp = (Elf_Addr)(def->st_value);
189 if (__predict_true(RELOC_ALIGNED_P(where)))
190 *where = tmp;
191 else
192 store_ptr(where, tmp);
193
194 rdbg(("TLS_DTPOFF32 %s in %s --> %p",
195 obj->strtab + obj->symtab[symnum].st_name,
196 obj->path, (void *)tmp));
197
198 break;
199 case R_TYPE(TLS_DTPMOD32):
200 def = _rtld_find_symdef(symnum, obj, &defobj, false);
201 if (def == NULL)
202 return -1;
203
204 tmp = (Elf_Addr)(defobj->tlsindex);
205 if (__predict_true(RELOC_ALIGNED_P(where)))
206 *where = tmp;
207 else
208 store_ptr(where, tmp);
209
210 rdbg(("TLS_DTPMOD32 %s in %s --> %p",
211 obj->strtab + obj->symtab[symnum].st_name,
212 obj->path, (void *)tmp));
213
214 break;
215
216 case R_TYPE(TLS_TPOFF32):
217 def = _rtld_find_symdef(symnum, obj, &defobj, false);
218 if (def == NULL)
219 return -1;
220
221 if (!defobj->tls_done &&
222 _rtld_tls_offset_allocate(obj))
223 return -1;
224
225 tmp = (Elf_Addr)def->st_value + defobj->tlsoffset +
226 sizeof(struct tls_tcb);
227 if (__predict_true(RELOC_ALIGNED_P(where)))
228 *where = tmp;
229 else
230 store_ptr(where, tmp);
231 rdbg(("TLS_TPOFF32 %s in %s --> %p",
232 obj->strtab + obj->symtab[symnum].st_name,
233 obj->path, (void *)tmp));
234 break;
235 #endif /* defined(__minix) && defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II) */
236
237 default:
238 rdbg(("sym = %lu, type = %lu, offset = %p, "
239 "contents = %p, symbol = %s",
240 symnum, (u_long)ELF_R_TYPE(rel->r_info),
241 (void *)rel->r_offset, (void *)load_ptr(where),
242 obj->strtab + obj->symtab[symnum].st_name));
243 _rtld_error("%s: Unsupported relocation type %ld "
244 "in non-PLT relocations",
245 obj->path, (u_long) ELF_R_TYPE(rel->r_info));
246 return -1;
247 }
248 }
249 return 0;
250 }
251
252 int
_rtld_relocate_plt_lazy(const Obj_Entry * obj)253 _rtld_relocate_plt_lazy(const Obj_Entry *obj)
254 {
255 const Elf_Rel *rel;
256
257 if (!obj->relocbase)
258 return 0;
259
260 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
261 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
262
263 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT));
264
265 /* Just relocate the GOT slots pointing into the PLT */
266 *where += (Elf_Addr)obj->relocbase;
267 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
268 }
269
270 return 0;
271 }
272
273 static int
_rtld_relocate_plt_object(const Obj_Entry * obj,const Elf_Rel * rel,Elf_Addr * tp)274 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel,
275 Elf_Addr *tp)
276 {
277 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
278 Elf_Addr new_value;
279 const Elf_Sym *def;
280 const Obj_Entry *defobj;
281 unsigned long info = rel->r_info;
282
283 assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT));
284
285 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
286 if (__predict_false(def == NULL))
287 return -1;
288 if (__predict_false(def == &_rtld_sym_zero))
289 return 0;
290
291 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
292 if (tp == NULL)
293 return 0;
294 new_value = _rtld_resolve_ifunc(defobj, def);
295 } else {
296 new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
297 }
298 /* Set the Thumb bit, if needed. */
299 if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC)
300 new_value |= 1;
301 rdbg(("bind now/fixup in %s --> old=%p new=%p",
302 defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
303 if (*where != new_value)
304 *where = new_value;
305 if (tp)
306 *tp = new_value;
307
308 return 0;
309 }
310
311 caddr_t
_rtld_bind(const Obj_Entry * obj,Elf_Word reloff)312 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
313 {
314 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel + reloff);
315 Elf_Addr new_value = 0; /* XXX gcc */
316 int err;
317
318 _rtld_shared_enter();
319 err = _rtld_relocate_plt_object(obj, rel, &new_value);
320 if (err)
321 _rtld_die();
322 _rtld_shared_exit();
323
324 return (caddr_t)new_value;
325 }
326 int
_rtld_relocate_plt_objects(const Obj_Entry * obj)327 _rtld_relocate_plt_objects(const Obj_Entry *obj)
328 {
329 const Elf_Rel *rel;
330 int err = 0;
331
332 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
333 err = _rtld_relocate_plt_object(obj, rel, NULL);
334 if (err)
335 break;
336 }
337
338 return err;
339 }
340