xref: /freebsd/libexec/rtld-elf/powerpc64/reloc.c (revision a25896ca1270e25b657ceaa8d47d5699515f5c25)
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 *)((const char *) 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 *)((const char *)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 __unused, Obj_Entry *obj,
161     const Elf_Rela *rela, 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(
250 				    __DECONST(Obj_Entry *, defobj))) {
251 				_rtld_error("%s: No space available for static "
252 				    "Thread Local Storage", obj->path);
253 				return (-1);
254 			}
255 		}
256 
257 		*(Elf_Addr **)where = *where * sizeof(Elf_Addr)
258 		    + (Elf_Addr *)(def->st_value + rela->r_addend
259 		    + defobj->tlsoffset - TLS_TP_OFFSET);
260 
261 		break;
262 
263 	case R_PPC64_DTPREL64:
264 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
265 		    flags, cache, lockstate);
266 
267 		if (def == NULL)
268 			return (-1);
269 
270 		*where += (Elf_Addr)(def->st_value + rela->r_addend
271 		    - TLS_DTV_OFFSET);
272 
273 		break;
274 
275 	default:
276 		_rtld_error("%s: Unsupported relocation type %ld"
277 			    " in non-PLT relocations\n", obj->path,
278 			    ELF_R_TYPE(rela->r_info));
279 		return (-1);
280         }
281 	return (0);
282 }
283 
284 
285 /*
286  * Process non-PLT relocations
287  */
288 int
289 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags,
290     RtldLockState *lockstate)
291 {
292 	const Elf_Rela *relalim;
293 	const Elf_Rela *rela;
294 	const Elf_Phdr *phdr;
295 	SymCache *cache;
296 	int bytes = obj->dynsymcount * sizeof(SymCache);
297 	int r = -1;
298 
299 	if ((flags & SYMLOOK_IFUNC) != 0)
300 		/* XXX not implemented */
301 		return (0);
302 
303 	/*
304 	 * The dynamic loader may be called from a thread, we have
305 	 * limited amounts of stack available so we cannot use alloca().
306 	 */
307 	if (obj != obj_rtld) {
308 		cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON,
309 		    -1, 0);
310 		if (cache == MAP_FAILED)
311 			cache = NULL;
312 	} else
313 		cache = NULL;
314 
315 	/*
316 	 * From the SVR4 PPC ABI:
317 	 * "The PowerPC family uses only the Elf32_Rela relocation
318 	 *  entries with explicit addends."
319 	 */
320 	relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize);
321 	for (rela = obj->rela; rela < relalim; rela++) {
322 		if (reloc_nonplt_object(obj_rtld, obj, rela, cache, flags,
323 		    lockstate) < 0)
324 			goto done;
325 	}
326 	r = 0;
327 done:
328 	if (cache)
329 		munmap(cache, bytes);
330 
331 	/*
332 	 * Synchronize icache for executable segments in case we made
333 	 * any changes.
334 	 */
335 	for (phdr = obj->phdr;
336 	    (const char *)phdr < (const char *)obj->phdr + obj->phsize;
337 	    phdr++) {
338 		if (phdr->p_type == PT_LOAD && (phdr->p_flags & PF_X) != 0) {
339 			__syncicache(obj->relocbase + phdr->p_vaddr,
340 			    phdr->p_memsz);
341 		}
342 	}
343 
344 	return (r);
345 }
346 
347 
348 /*
349  * Initialise a PLT slot to the resolving trampoline
350  */
351 static int
352 reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela)
353 {
354 	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
355 	long reloff;
356 
357 	reloff = rela - obj->pltrela;
358 
359 	dbg(" reloc_plt_object: where=%p,reloff=%lx,glink=%#lx", (void *)where,
360 	    reloff, obj->glink);
361 
362 #if !defined(_CALL_ELF) || _CALL_ELF == 1
363 	/* Glink code is 3 instructions after the first 32k, 2 before */
364 	*where = (Elf_Addr)obj->glink + 32 +
365 	    8*((reloff < 0x8000) ? reloff : 0x8000) +
366 	    12*((reloff < 0x8000) ? 0 : (reloff - 0x8000));
367 #else
368 	*where = (Elf_Addr)obj->glink + 4*reloff + 32;
369 #endif
370 
371 	return (0);
372 }
373 
374 
375 /*
376  * Process the PLT relocations.
377  */
378 int
379 reloc_plt(Obj_Entry *obj)
380 {
381 	const Elf_Rela *relalim;
382 	const Elf_Rela *rela;
383 
384 	if (obj->pltrelasize != 0) {
385 		relalim = (const Elf_Rela *)((const char *)obj->pltrela +
386 		    obj->pltrelasize);
387 		for (rela = obj->pltrela;  rela < relalim;  rela++) {
388 			assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
389 
390 			if (reloc_plt_object(obj, rela) < 0) {
391 				return (-1);
392 			}
393 		}
394 	}
395 
396 	return (0);
397 }
398 
399 
400 /*
401  * LD_BIND_NOW was set - force relocation for all jump slots
402  */
403 int
404 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
405 {
406 	const Obj_Entry *defobj;
407 	const Elf_Rela *relalim;
408 	const Elf_Rela *rela;
409 	const Elf_Sym *def;
410 	Elf_Addr *where;
411 	Elf_Addr target;
412 
413 	relalim = (const Elf_Rela *)((const char *)obj->pltrela +
414 	    obj->pltrelasize);
415 	for (rela = obj->pltrela; rela < relalim; rela++) {
416 		assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
417 		where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
418 		def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
419 		    SYMLOOK_IN_PLT | flags, NULL, lockstate);
420 		if (def == NULL) {
421 			dbg("reloc_jmpslots: sym not found");
422 			return (-1);
423 		}
424 
425 		target = (Elf_Addr)(defobj->relocbase + def->st_value);
426 
427 		if (def == &sym_zero) {
428 			/* Zero undefined weak symbols */
429 #if !defined(_CALL_ELF) || _CALL_ELF == 1
430 			bzero(where, sizeof(struct funcdesc));
431 #else
432 			*where = 0;
433 #endif
434 		} else {
435 			reloc_jmpslot(where, target, defobj, obj,
436 			    (const Elf_Rel *) rela);
437 		}
438 	}
439 
440 	obj->jmpslots_done = true;
441 
442 	return (0);
443 }
444 
445 
446 /*
447  * Update the value of a PLT jump slot.
448  */
449 Elf_Addr
450 reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target, const Obj_Entry *defobj,
451     const Obj_Entry *obj __unused, const Elf_Rel *rel __unused)
452 {
453 
454 	/*
455 	 * At the PLT entry pointed at by `wherep', construct
456 	 * a direct transfer to the now fully resolved function
457 	 * address.
458 	 */
459 
460 #if !defined(_CALL_ELF) || _CALL_ELF == 1
461 	dbg(" reloc_jmpslot: where=%p, target=%p (%#lx + %#lx)",
462 	    (void *)wherep, (void *)target, *(Elf_Addr *)target,
463 	    (Elf_Addr)defobj->relocbase);
464 
465 	if (ld_bind_not)
466 		goto out;
467 
468 	/*
469 	 * For the trampoline, the second two elements of the function
470 	 * descriptor are unused, so we are fine replacing those at any time
471 	 * with the real ones with no thread safety implications. However, we
472 	 * need to make sure the main entry point pointer ([0]) is seen to be
473 	 * modified *after* the second two elements. This can't be done in
474 	 * general, since there are no barriers in the reading code, but put in
475 	 * some isyncs to at least make it a little better.
476 	 */
477 	memcpy(wherep, (void *)target, sizeof(struct funcdesc));
478 	wherep[2] = ((Elf_Addr *)target)[2];
479 	wherep[1] = ((Elf_Addr *)target)[1];
480 	__asm __volatile ("isync" : : : "memory");
481 	wherep[0] = ((Elf_Addr *)target)[0];
482 	__asm __volatile ("isync" : : : "memory");
483 
484 	if (((struct funcdesc *)(wherep))->addr < (Elf_Addr)defobj->relocbase) {
485 		/*
486 		 * It is possible (LD_BIND_NOW) that the function
487 		 * descriptor we are copying has not yet been relocated.
488 		 * If this happens, fix it. Don't worry about threading in
489 		 * this case since LD_BIND_NOW makes it irrelevant.
490 		 */
491 
492 		((struct funcdesc *)(wherep))->addr +=
493 		    (Elf_Addr)defobj->relocbase;
494 		((struct funcdesc *)(wherep))->toc +=
495 		    (Elf_Addr)defobj->relocbase;
496 	}
497 out:
498 #else
499 	dbg(" reloc_jmpslot: where=%p, target=%p", (void *)wherep,
500 	    (void *)target);
501 
502 	if (!ld_bind_not)
503 		*wherep = target;
504 #endif
505 
506 	return (target);
507 }
508 
509 int
510 reloc_iresolve(Obj_Entry *obj __unused,
511     struct Struct_RtldLockState *lockstate __unused)
512 {
513 
514 	/* XXX not implemented */
515 	return (0);
516 }
517 
518 int
519 reloc_gnu_ifunc(Obj_Entry *obj __unused, int flags __unused,
520     struct Struct_RtldLockState *lockstate __unused)
521 {
522 
523 	/* XXX not implemented */
524 	return (0);
525 }
526 
527 void
528 init_pltgot(Obj_Entry *obj)
529 {
530 	Elf_Addr *pltcall;
531 
532 	pltcall = obj->pltgot;
533 
534 	if (pltcall == NULL) {
535 		return;
536 	}
537 
538 #if defined(_CALL_ELF) && _CALL_ELF == 2
539 	pltcall[0] = (Elf_Addr)&_rtld_bind_start;
540 	pltcall[1] = (Elf_Addr)obj;
541 #else
542 	memcpy(pltcall, _rtld_bind_start, sizeof(struct funcdesc));
543 	pltcall[2] = (Elf_Addr)obj;
544 #endif
545 }
546 
547 void
548 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused)
549 {
550 
551 }
552 
553 void
554 pre_init(void)
555 {
556 
557 }
558 
559 void
560 allocate_initial_tls(Obj_Entry *list)
561 {
562 	Elf_Addr **tp;
563 
564 	/*
565 	* Fix the size of the static TLS block by using the maximum
566 	* offset allocated so far and adding a bit for dynamic modules to
567 	* use.
568 	*/
569 
570 	tls_static_space = tls_last_offset + tls_last_size + RTLD_STATIC_TLS_EXTRA;
571 
572 	tp = (Elf_Addr **)((char *)allocate_tls(list, NULL, TLS_TCB_SIZE, 16)
573 	    + TLS_TP_OFFSET + TLS_TCB_SIZE);
574 
575 	__asm __volatile("mr 13,%0" :: "r"(tp));
576 }
577 
578 void*
579 __tls_get_addr(tls_index* ti)
580 {
581 	Elf_Addr **tp;
582 	char *p;
583 
584 	__asm __volatile("mr %0,13" : "=r"(tp));
585 	p = tls_get_addr_common((Elf_Addr**)((Elf_Addr)tp - TLS_TP_OFFSET
586 	    - TLS_TCB_SIZE), ti->ti_module, ti->ti_offset);
587 
588 	return (p + TLS_DTV_OFFSET);
589 }
590