1 /*-
2 * Copyright (c) 2014-2015 The FreeBSD Foundation
3 * All rights reserved.
4 *
5 * Portions of this software were developed by Andrew Turner
6 * under sponsorship from the FreeBSD Foundation.
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 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32
33 #include <sys/types.h>
34
35 #include <stdlib.h>
36
37 #include "debug.h"
38 #include "rtld.h"
39 #include "rtld_printf.h"
40
41 /*
42 * It is possible for the compiler to emit relocations for unaligned data.
43 * We handle this situation with these inlines.
44 */
45 #define RELOC_ALIGNED_P(x) \
46 (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
47
48 /*
49 * This is not the correct prototype, but we only need it for
50 * a function pointer to a simple asm function.
51 */
52 void *_rtld_tlsdesc(void *);
53 void *_rtld_tlsdesc_dynamic(void *);
54
55 void _exit(int);
56
57 void
init_pltgot(Obj_Entry * obj)58 init_pltgot(Obj_Entry *obj)
59 {
60
61 if (obj->pltgot != NULL) {
62 obj->pltgot[1] = (Elf_Addr) obj;
63 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
64 }
65 }
66
67 int
do_copy_relocations(Obj_Entry * dstobj)68 do_copy_relocations(Obj_Entry *dstobj)
69 {
70 const Obj_Entry *srcobj, *defobj;
71 const Elf_Rela *relalim;
72 const Elf_Rela *rela;
73 const Elf_Sym *srcsym;
74 const Elf_Sym *dstsym;
75 const void *srcaddr;
76 const char *name;
77 void *dstaddr;
78 SymLook req;
79 size_t size;
80 int res;
81
82 /*
83 * COPY relocs are invalid outside of the main program
84 */
85 assert(dstobj->mainprog);
86
87 relalim = (const Elf_Rela *)((char *)dstobj->rela +
88 dstobj->relasize);
89 for (rela = dstobj->rela; rela < relalim; rela++) {
90 if (ELF_R_TYPE(rela->r_info) != R_AARCH64_COPY)
91 continue;
92
93 dstaddr = (void *)(dstobj->relocbase + rela->r_offset);
94 dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
95 name = dstobj->strtab + dstsym->st_name;
96 size = dstsym->st_size;
97
98 symlook_init(&req, name);
99 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info));
100 req.flags = SYMLOOK_EARLY;
101
102 for (srcobj = dstobj->next; srcobj != NULL;
103 srcobj = srcobj->next) {
104 res = symlook_obj(&req, srcobj);
105 if (res == 0) {
106 srcsym = req.sym_out;
107 defobj = req.defobj_out;
108 break;
109 }
110 }
111 if (srcobj == NULL) {
112 _rtld_error(
113 "Undefined symbol \"%s\" referenced from COPY relocation in %s",
114 name, dstobj->path);
115 return (-1);
116 }
117
118 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value);
119 memcpy(dstaddr, srcaddr, size);
120 }
121
122 return (0);
123 }
124
125 struct tls_data {
126 int64_t index;
127 Obj_Entry *obj;
128 const Elf_Rela *rela;
129 };
130
131 static struct tls_data *
reloc_tlsdesc_alloc(Obj_Entry * obj,const Elf_Rela * rela)132 reloc_tlsdesc_alloc(Obj_Entry *obj, const Elf_Rela *rela)
133 {
134 struct tls_data *tlsdesc;
135
136 tlsdesc = xmalloc(sizeof(struct tls_data));
137 tlsdesc->index = -1;
138 tlsdesc->obj = obj;
139 tlsdesc->rela = rela;
140
141 return (tlsdesc);
142 }
143
144 /*
145 * Look up the symbol to find its tls index
146 */
147 static int64_t
rtld_tlsdesc_handle_locked(struct tls_data * tlsdesc,int flags,RtldLockState * lockstate)148 rtld_tlsdesc_handle_locked(struct tls_data *tlsdesc, int flags,
149 RtldLockState *lockstate)
150 {
151 const Elf_Rela *rela;
152 const Elf_Sym *def;
153 const Obj_Entry *defobj;
154 Obj_Entry *obj;
155
156 rela = tlsdesc->rela;
157 obj = tlsdesc->obj;
158
159 def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, flags, NULL,
160 lockstate);
161 if (def == NULL)
162 rtld_die();
163
164 tlsdesc->index = defobj->tlsoffset + def->st_value + rela->r_addend;
165
166 return (tlsdesc->index);
167 }
168
169 int64_t
rtld_tlsdesc_handle(struct tls_data * tlsdesc,int flags)170 rtld_tlsdesc_handle(struct tls_data *tlsdesc, int flags)
171 {
172 RtldLockState lockstate;
173
174 /* We have already found the index, return it */
175 if (tlsdesc->index >= 0)
176 return (tlsdesc->index);
177
178 wlock_acquire(rtld_bind_lock, &lockstate);
179 /* tlsdesc->index may have been set by another thread */
180 if (tlsdesc->index == -1)
181 rtld_tlsdesc_handle_locked(tlsdesc, flags, &lockstate);
182 lock_release(rtld_bind_lock, &lockstate);
183
184 return (tlsdesc->index);
185 }
186
187 /*
188 * Process the PLT relocations.
189 */
190 int
reloc_plt(Obj_Entry * obj)191 reloc_plt(Obj_Entry *obj)
192 {
193 const Elf_Rela *relalim;
194 const Elf_Rela *rela;
195
196 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
197 for (rela = obj->pltrela; rela < relalim; rela++) {
198 Elf_Addr *where;
199
200 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
201
202 switch(ELF_R_TYPE(rela->r_info)) {
203 case R_AARCH64_JUMP_SLOT:
204 *where += (Elf_Addr)obj->relocbase;
205 break;
206 case R_AARCH64_TLSDESC:
207 if (ELF_R_SYM(rela->r_info) == 0) {
208 where[0] = (Elf_Addr)_rtld_tlsdesc;
209 where[1] = obj->tlsoffset + rela->r_addend;
210 } else {
211 where[0] = (Elf_Addr)_rtld_tlsdesc_dynamic;
212 where[1] = (Elf_Addr)reloc_tlsdesc_alloc(obj,
213 rela);
214 }
215 break;
216 default:
217 _rtld_error("Unknown relocation type %u in PLT",
218 (unsigned int)ELF_R_TYPE(rela->r_info));
219 return (-1);
220 }
221 }
222
223 return (0);
224 }
225
226 /*
227 * LD_BIND_NOW was set - force relocation for all jump slots
228 */
229 int
reloc_jmpslots(Obj_Entry * obj,int flags,RtldLockState * lockstate)230 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
231 {
232 const Obj_Entry *defobj;
233 const Elf_Rela *relalim;
234 const Elf_Rela *rela;
235 const Elf_Sym *def;
236 struct tls_data *tlsdesc;
237
238 relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
239 for (rela = obj->pltrela; rela < relalim; rela++) {
240 Elf_Addr *where;
241
242 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
243 switch(ELF_R_TYPE(rela->r_info)) {
244 case R_AARCH64_JUMP_SLOT:
245 def = find_symdef(ELF_R_SYM(rela->r_info), obj,
246 &defobj, SYMLOOK_IN_PLT | flags, NULL, lockstate);
247 if (def == NULL) {
248 dbg("reloc_jmpslots: sym not found");
249 return (-1);
250 }
251
252 *where = (Elf_Addr)(defobj->relocbase + def->st_value);
253 break;
254 case R_AARCH64_TLSDESC:
255 if (ELF_R_SYM(rela->r_info) != 0) {
256 tlsdesc = (struct tls_data *)where[1];
257 if (tlsdesc->index == -1)
258 rtld_tlsdesc_handle_locked(tlsdesc,
259 SYMLOOK_IN_PLT | flags, lockstate);
260 }
261 break;
262 default:
263 _rtld_error("Unknown relocation type %x in jmpslot",
264 (unsigned int)ELF_R_TYPE(rela->r_info));
265 return (-1);
266 }
267 }
268
269 return (0);
270 }
271
272 int
reloc_iresolve(Obj_Entry * obj,struct Struct_RtldLockState * lockstate)273 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate)
274 {
275
276 /* XXX not implemented */
277 return (0);
278 }
279
280 int
reloc_gnu_ifunc(Obj_Entry * obj,int flags,struct Struct_RtldLockState * lockstate)281 reloc_gnu_ifunc(Obj_Entry *obj, int flags,
282 struct Struct_RtldLockState *lockstate)
283 {
284
285 /* XXX not implemented */
286 return (0);
287 }
288
289 Elf_Addr
reloc_jmpslot(Elf_Addr * where,Elf_Addr target,const Obj_Entry * defobj,const Obj_Entry * obj,const Elf_Rel * rel)290 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *defobj,
291 const Obj_Entry *obj, const Elf_Rel *rel)
292 {
293
294 assert(ELF_R_TYPE(rel->r_info) == R_AARCH64_JUMP_SLOT);
295
296 if (*where != target)
297 *where = target;
298
299 return target;
300 }
301
302 /*
303 * Process non-PLT relocations
304 */
305 int
reloc_non_plt(Obj_Entry * obj,Obj_Entry * obj_rtld,int flags,RtldLockState * lockstate)306 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags,
307 RtldLockState *lockstate)
308 {
309 const Obj_Entry *defobj;
310 const Elf_Rela *relalim;
311 const Elf_Rela *rela;
312 const Elf_Sym *def;
313 SymCache *cache;
314 Elf_Addr *where;
315 unsigned long symnum;
316
317 if ((flags & SYMLOOK_IFUNC) != 0)
318 /* XXX not implemented */
319 return (0);
320
321 /*
322 * The dynamic loader may be called from a thread, we have
323 * limited amounts of stack available so we cannot use alloca().
324 */
325 if (obj == obj_rtld)
326 cache = NULL;
327 else
328 cache = calloc(obj->dynsymcount, sizeof(SymCache));
329 /* No need to check for NULL here */
330
331 relalim = (const Elf_Rela *)((caddr_t)obj->rela + obj->relasize);
332 for (rela = obj->rela; rela < relalim; rela++) {
333 where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
334 symnum = ELF_R_SYM(rela->r_info);
335
336 switch (ELF_R_TYPE(rela->r_info)) {
337 case R_AARCH64_ABS64:
338 case R_AARCH64_GLOB_DAT:
339 def = find_symdef(symnum, obj, &defobj, flags, cache,
340 lockstate);
341 if (def == NULL)
342 return (-1);
343
344 *where = (Elf_Addr)defobj->relocbase + def->st_value +
345 rela->r_addend;
346 break;
347 case R_AARCH64_COPY:
348 /*
349 * These are deferred until all other relocations have
350 * been done. All we do here is make sure that the
351 * COPY relocation is not in a shared library. They
352 * are allowed only in executable files.
353 */
354 if (!obj->mainprog) {
355 _rtld_error("%s: Unexpected R_AARCH64_COPY "
356 "relocation in shared library", obj->path);
357 return (-1);
358 }
359 break;
360 case R_AARCH64_TLS_TPREL64:
361 def = find_symdef(symnum, obj, &defobj, flags, cache,
362 lockstate);
363 if (def == NULL)
364 return (-1);
365
366 /*
367 * We lazily allocate offsets for static TLS as we
368 * see the first relocation that references the
369 * TLS block. This allows us to support (small
370 * amounts of) static TLS in dynamically loaded
371 * modules. If we run out of space, we generate an
372 * error.
373 */
374 if (!defobj->tls_done) {
375 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
376 _rtld_error(
377 "%s: No space available for static "
378 "Thread Local Storage", obj->path);
379 return (-1);
380 }
381 }
382
383 *where = def->st_value + rela->r_addend +
384 defobj->tlsoffset;
385 break;
386 case R_AARCH64_RELATIVE:
387 *where = (Elf_Addr)(obj->relocbase + rela->r_addend);
388 break;
389 default:
390 rtld_printf("%s: Unhandled relocation %lu\n",
391 obj->path, ELF_R_TYPE(rela->r_info));
392 return (-1);
393 }
394 }
395
396 return (0);
397 }
398
399 void
allocate_initial_tls(Obj_Entry * objs)400 allocate_initial_tls(Obj_Entry *objs)
401 {
402 Elf_Addr **tp;
403
404 /*
405 * Fix the size of the static TLS block by using the maximum
406 * offset allocated so far and adding a bit for dynamic modules to
407 * use.
408 */
409 tls_static_space = tls_last_offset + tls_last_size +
410 RTLD_STATIC_TLS_EXTRA;
411
412 tp = (Elf_Addr **) allocate_tls(objs, NULL, TLS_TCB_SIZE, 16);
413
414 asm volatile("msr tpidr_el0, %0" : : "r"(tp));
415 }
416