xref: /freebsd/libexec/rtld-elf/powerpc64/reloc.c (revision 1de7b4b805ddbf2429da511c053686ac4591ed89)
1 /*      $NetBSD: ppc_reloc.c,v 1.10 2001/09/10 06:09:41 mycroft Exp $   */
2 
3 /*-
4  * SPDX-License-Identifier: BSD-2-Clause-NetBSD
5  *
6  * Copyright (C) 1998   Tsubai Masanari
7  * All rights reserved.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  * 3. The name of the author may not be used to endorse or promote products
18  *    derived from this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
29  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30  *
31  * $FreeBSD$
32  */
33 
34 #include <sys/param.h>
35 #include <sys/mman.h>
36 
37 #include <errno.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <unistd.h>
42 #include <machine/cpu.h>
43 #include <machine/md_var.h>
44 
45 #include "debug.h"
46 #include "rtld.h"
47 
48 #if !defined(_CALL_ELF) || _CALL_ELF == 1
49 struct funcdesc {
50 	Elf_Addr addr;
51 	Elf_Addr toc;
52 	Elf_Addr env;
53 };
54 #endif
55 
56 /*
57  * Process the R_PPC_COPY relocations
58  */
59 int
60 do_copy_relocations(Obj_Entry *dstobj)
61 {
62 	const Elf_Rela *relalim;
63 	const Elf_Rela *rela;
64 
65 	/*
66 	 * COPY relocs are invalid outside of the main program
67 	 */
68 	assert(dstobj->mainprog);
69 
70 	relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela +
71 	    dstobj->relasize);
72 	for (rela = dstobj->rela;  rela < relalim;  rela++) {
73 		void *dstaddr;
74 		const Elf_Sym *dstsym;
75 		const char *name;
76 		size_t size;
77 		const void *srcaddr;
78 		const Elf_Sym *srcsym = NULL;
79 		const Obj_Entry *srcobj, *defobj;
80 		SymLook req;
81 		int res;
82 
83 		if (ELF_R_TYPE(rela->r_info) != R_PPC_COPY) {
84 			continue;
85 		}
86 
87 		dstaddr = (void *) (dstobj->relocbase + rela->r_offset);
88 		dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
89 		name = dstobj->strtab + dstsym->st_name;
90 		size = dstsym->st_size;
91 		symlook_init(&req, name);
92 		req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info));
93 		req.flags = SYMLOOK_EARLY;
94 
95 		for (srcobj = globallist_next(dstobj); srcobj != NULL;
96 		     srcobj = globallist_next(srcobj)) {
97 			res = symlook_obj(&req, srcobj);
98 			if (res == 0) {
99 				srcsym = req.sym_out;
100 				defobj = req.defobj_out;
101 				break;
102 			}
103 		}
104 
105 		if (srcobj == NULL) {
106 			_rtld_error("Undefined symbol \"%s\" "
107 				    " referenced from COPY"
108 				    " relocation in %s", name, dstobj->path);
109 			return (-1);
110 		}
111 
112 		srcaddr = (const void *) (defobj->relocbase+srcsym->st_value);
113 		memcpy(dstaddr, srcaddr, size);
114 		dbg("copy_reloc: src=%p,dst=%p,size=%zd\n",srcaddr,dstaddr,size);
115 	}
116 
117 	return (0);
118 }
119 
120 
121 /*
122  * Perform early relocation of the run-time linker image
123  */
124 void
125 reloc_non_plt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
126 {
127 	const Elf_Rela *rela = NULL, *relalim;
128 	Elf_Addr relasz = 0;
129 	Elf_Addr *where;
130 
131 	/*
132 	 * Extract the rela/relasz values from the dynamic section
133 	 */
134 	for (; dynp->d_tag != DT_NULL; dynp++) {
135 		switch (dynp->d_tag) {
136 		case DT_RELA:
137 			rela = (const Elf_Rela *)(relocbase+dynp->d_un.d_ptr);
138 			break;
139 		case DT_RELASZ:
140 			relasz = dynp->d_un.d_val;
141 			break;
142 		}
143 	}
144 
145 	/*
146 	 * Relocate these values
147 	 */
148 	relalim = (const Elf_Rela *)((caddr_t)rela + relasz);
149 	for (; rela < relalim; rela++) {
150 		where = (Elf_Addr *)(relocbase + rela->r_offset);
151 		*where = (Elf_Addr)(relocbase + rela->r_addend);
152 	}
153 }
154 
155 
156 /*
157  * Relocate a non-PLT object with addend.
158  */
159 static int
160 reloc_nonplt_object(Obj_Entry *obj_rtld, Obj_Entry *obj, const Elf_Rela *rela,
161     SymCache *cache, int flags, RtldLockState *lockstate)
162 {
163 	Elf_Addr        *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
164 	const Elf_Sym   *def;
165 	const Obj_Entry *defobj;
166 	Elf_Addr         tmp;
167 
168 	switch (ELF_R_TYPE(rela->r_info)) {
169 
170 	case R_PPC_NONE:
171 		break;
172 
173         case R_PPC64_UADDR64:    /* doubleword64 S + A */
174         case R_PPC64_ADDR64:
175         case R_PPC_GLOB_DAT:
176 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
177 		    flags, cache, lockstate);
178 		if (def == NULL) {
179 			return (-1);
180 		}
181 
182                 tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
183                     rela->r_addend);
184 
185 		/* Don't issue write if unnecessary; avoid COW page fault */
186                 if (*where != tmp) {
187                         *where = tmp;
188 		}
189                 break;
190 
191         case R_PPC_RELATIVE:  /* doubleword64 B + A */
192 		tmp = (Elf_Addr)(obj->relocbase + rela->r_addend);
193 
194 		/* As above, don't issue write unnecessarily */
195 		if (*where != tmp) {
196 			*where = tmp;
197 		}
198 		break;
199 
200 	case R_PPC_COPY:
201 		/*
202 		 * These are deferred until all other relocations
203 		 * have been done.  All we do here is make sure
204 		 * that the COPY relocation is not in a shared
205 		 * library.  They are allowed only in executable
206 		 * files.
207 		 */
208 		if (!obj->mainprog) {
209 			_rtld_error("%s: Unexpected R_COPY "
210 				    " relocation in shared library",
211 				    obj->path);
212 			return (-1);
213 		}
214 		break;
215 
216 	case R_PPC_JMP_SLOT:
217 		/*
218 		 * These will be handled by the plt/jmpslot routines
219 		 */
220 		break;
221 
222 	case R_PPC64_DTPMOD64:
223 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
224 		    flags, cache, lockstate);
225 
226 		if (def == NULL)
227 			return (-1);
228 
229 		*where = (Elf_Addr) defobj->tlsindex;
230 
231 		break;
232 
233 	case R_PPC64_TPREL64:
234 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
235 		    flags, cache, lockstate);
236 
237 		if (def == NULL)
238 			return (-1);
239 
240 		/*
241 		 * We lazily allocate offsets for static TLS as we
242 		 * see the first relocation that references the
243 		 * TLS block. This allows us to support (small
244 		 * amounts of) static TLS in dynamically loaded
245 		 * modules. If we run out of space, we generate an
246 		 * error.
247 		 */
248 		if (!defobj->tls_done) {
249 			if (!allocate_tls_offset((Obj_Entry*) defobj)) {
250 				_rtld_error("%s: No space available for static "
251 				    "Thread Local Storage", obj->path);
252 				return (-1);
253 			}
254 		}
255 
256 		*(Elf_Addr **)where = *where * sizeof(Elf_Addr)
257 		    + (Elf_Addr *)(def->st_value + rela->r_addend
258 		    + defobj->tlsoffset - TLS_TP_OFFSET);
259 
260 		break;
261 
262 	case R_PPC64_DTPREL64:
263 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
264 		    flags, cache, lockstate);
265 
266 		if (def == NULL)
267 			return (-1);
268 
269 		*where += (Elf_Addr)(def->st_value + rela->r_addend
270 		    - TLS_DTV_OFFSET);
271 
272 		break;
273 
274 	default:
275 		_rtld_error("%s: Unsupported relocation type %ld"
276 			    " in non-PLT relocations\n", obj->path,
277 			    ELF_R_TYPE(rela->r_info));
278 		return (-1);
279         }
280 	return (0);
281 }
282 
283 
284 /*
285  * Process non-PLT relocations
286  */
287 int
288 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags,
289     RtldLockState *lockstate)
290 {
291 	const Elf_Rela *relalim;
292 	const Elf_Rela *rela;
293 	SymCache *cache;
294 	int bytes = obj->dynsymcount * sizeof(SymCache);
295 	int r = -1;
296 
297 	if ((flags & SYMLOOK_IFUNC) != 0)
298 		/* XXX not implemented */
299 		return (0);
300 
301 	/*
302 	 * The dynamic loader may be called from a thread, we have
303 	 * limited amounts of stack available so we cannot use alloca().
304 	 */
305 	if (obj != obj_rtld) {
306 		cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON,
307 		    -1, 0);
308 		if (cache == MAP_FAILED)
309 			cache = NULL;
310 	} else
311 		cache = NULL;
312 
313 	/*
314 	 * From the SVR4 PPC ABI:
315 	 * "The PowerPC family uses only the Elf32_Rela relocation
316 	 *  entries with explicit addends."
317 	 */
318 	relalim = (const Elf_Rela *)((caddr_t)obj->rela + obj->relasize);
319 	for (rela = obj->rela; rela < relalim; rela++) {
320 		if (reloc_nonplt_object(obj_rtld, obj, rela, cache, flags,
321 		    lockstate) < 0)
322 			goto done;
323 	}
324 	r = 0;
325 done:
326 	if (cache)
327 		munmap(cache, bytes);
328 
329 	/* Synchronize icache for text seg in case we made any changes */
330 	__syncicache(obj->mapbase, obj->textsize);
331 
332 	return (r);
333 }
334 
335 
336 /*
337  * Initialise a PLT slot to the resolving trampoline
338  */
339 static int
340 reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela)
341 {
342 	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
343 	long reloff;
344 
345 	reloff = rela - obj->pltrela;
346 
347 	dbg(" reloc_plt_object: where=%p,reloff=%lx,glink=%#lx", (void *)where,
348 	    reloff, obj->glink);
349 
350 #if !defined(_CALL_ELF) || _CALL_ELF == 1
351 	/* Glink code is 3 instructions after the first 32k, 2 before */
352 	*where = (Elf_Addr)obj->glink + 32 +
353 	    8*((reloff < 0x8000) ? reloff : 0x8000) +
354 	    12*((reloff < 0x8000) ? 0 : (reloff - 0x8000));
355 #else
356 	*where = (Elf_Addr)obj->glink + 4*reloff + 32;
357 #endif
358 
359 	return (0);
360 }
361 
362 
363 /*
364  * Process the PLT relocations.
365  */
366 int
367 reloc_plt(Obj_Entry *obj)
368 {
369 	const Elf_Rela *relalim;
370 	const Elf_Rela *rela;
371 
372 	if (obj->pltrelasize != 0) {
373 		relalim = (const Elf_Rela *)((char *)obj->pltrela +
374 		    obj->pltrelasize);
375 		for (rela = obj->pltrela;  rela < relalim;  rela++) {
376 			assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
377 
378 			if (reloc_plt_object(obj, rela) < 0) {
379 				return (-1);
380 			}
381 		}
382 	}
383 
384 	return (0);
385 }
386 
387 
388 /*
389  * LD_BIND_NOW was set - force relocation for all jump slots
390  */
391 int
392 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
393 {
394 	const Obj_Entry *defobj;
395 	const Elf_Rela *relalim;
396 	const Elf_Rela *rela;
397 	const Elf_Sym *def;
398 	Elf_Addr *where;
399 	Elf_Addr target;
400 
401 	relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
402 	for (rela = obj->pltrela; rela < relalim; rela++) {
403 		assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
404 		where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
405 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
406 		    SYMLOOK_IN_PLT | flags, NULL, lockstate);
407 		if (def == NULL) {
408 			dbg("reloc_jmpslots: sym not found");
409 			return (-1);
410 		}
411 
412 		target = (Elf_Addr)(defobj->relocbase + def->st_value);
413 
414 		if (def == &sym_zero) {
415 			/* Zero undefined weak symbols */
416 #if !defined(_CALL_ELF) || _CALL_ELF == 1
417 			bzero(where, sizeof(struct funcdesc));
418 #else
419 			*where = 0;
420 #endif
421 		} else {
422 			reloc_jmpslot(where, target, defobj, obj,
423 			    (const Elf_Rel *) rela);
424 		}
425 	}
426 
427 	obj->jmpslots_done = true;
428 
429 	return (0);
430 }
431 
432 
433 /*
434  * Update the value of a PLT jump slot.
435  */
436 Elf_Addr
437 reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target, const Obj_Entry *defobj,
438     const Obj_Entry *obj, const Elf_Rel *rel)
439 {
440 
441 	/*
442 	 * At the PLT entry pointed at by `wherep', construct
443 	 * a direct transfer to the now fully resolved function
444 	 * address.
445 	 */
446 
447 #if !defined(_CALL_ELF) || _CALL_ELF == 1
448 	dbg(" reloc_jmpslot: where=%p, target=%p (%#lx + %#lx)",
449 	    (void *)wherep, (void *)target, *(Elf_Addr *)target,
450 	    (Elf_Addr)defobj->relocbase);
451 
452 	if (ld_bind_not)
453 		goto out;
454 
455 	/*
456 	 * For the trampoline, the second two elements of the function
457 	 * descriptor are unused, so we are fine replacing those at any time
458 	 * with the real ones with no thread safety implications. However, we
459 	 * need to make sure the main entry point pointer ([0]) is seen to be
460 	 * modified *after* the second two elements. This can't be done in
461 	 * general, since there are no barriers in the reading code, but put in
462 	 * some isyncs to at least make it a little better.
463 	 */
464 	memcpy(wherep, (void *)target, sizeof(struct funcdesc));
465 	wherep[2] = ((Elf_Addr *)target)[2];
466 	wherep[1] = ((Elf_Addr *)target)[1];
467 	__asm __volatile ("isync" : : : "memory");
468 	wherep[0] = ((Elf_Addr *)target)[0];
469 	__asm __volatile ("isync" : : : "memory");
470 
471 	if (((struct funcdesc *)(wherep))->addr < (Elf_Addr)defobj->relocbase) {
472 		/*
473 		 * It is possible (LD_BIND_NOW) that the function
474 		 * descriptor we are copying has not yet been relocated.
475 		 * If this happens, fix it. Don't worry about threading in
476 		 * this case since LD_BIND_NOW makes it irrelevant.
477 		 */
478 
479 		((struct funcdesc *)(wherep))->addr +=
480 		    (Elf_Addr)defobj->relocbase;
481 		((struct funcdesc *)(wherep))->toc +=
482 		    (Elf_Addr)defobj->relocbase;
483 	}
484 out:
485 #else
486 	dbg(" reloc_jmpslot: where=%p, target=%p", (void *)wherep,
487 	    (void *)target);
488 
489 	if (!ld_bind_not)
490 		*wherep = target;
491 #endif
492 
493 	return (target);
494 }
495 
496 int
497 reloc_iresolve(Obj_Entry *obj, struct Struct_RtldLockState *lockstate)
498 {
499 
500 	/* XXX not implemented */
501 	return (0);
502 }
503 
504 int
505 reloc_gnu_ifunc(Obj_Entry *obj, int flags,
506     struct Struct_RtldLockState *lockstate)
507 {
508 
509 	/* XXX not implemented */
510 	return (0);
511 }
512 
513 void
514 init_pltgot(Obj_Entry *obj)
515 {
516 	Elf_Addr *pltcall;
517 
518 	pltcall = obj->pltgot;
519 
520 	if (pltcall == NULL) {
521 		return;
522 	}
523 
524 #if defined(_CALL_ELF) && _CALL_ELF == 2
525 	pltcall[0] = (Elf_Addr)&_rtld_bind_start;
526 	pltcall[1] = (Elf_Addr)obj;
527 #else
528 	memcpy(pltcall, _rtld_bind_start, sizeof(struct funcdesc));
529 	pltcall[2] = (Elf_Addr)obj;
530 #endif
531 }
532 
533 void
534 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused)
535 {
536 }
537 
538 void
539 allocate_initial_tls(Obj_Entry *list)
540 {
541 	Elf_Addr **tp;
542 
543 	/*
544 	* Fix the size of the static TLS block by using the maximum
545 	* offset allocated so far and adding a bit for dynamic modules to
546 	* use.
547 	*/
548 
549 	tls_static_space = tls_last_offset + tls_last_size + RTLD_STATIC_TLS_EXTRA;
550 
551 	tp = (Elf_Addr **) ((char *)allocate_tls(list, NULL, TLS_TCB_SIZE, 16)
552 	    + TLS_TP_OFFSET + TLS_TCB_SIZE);
553 
554 	__asm __volatile("mr 13,%0" :: "r"(tp));
555 }
556 
557 void*
558 __tls_get_addr(tls_index* ti)
559 {
560 	Elf_Addr **tp;
561 	char *p;
562 
563 	__asm __volatile("mr %0,13" : "=r"(tp));
564 	p = tls_get_addr_common((Elf_Addr**)((Elf_Addr)tp - TLS_TP_OFFSET
565 	    - TLS_TCB_SIZE), ti->ti_module, ti->ti_offset);
566 
567 	return (p + TLS_DTV_OFFSET);
568 }
569