2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright 1996, 1997, 1998, 1999 John D. Polstra.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 * Dynamic linker for ELF.
33 * John Polstra <jdp@polstra.com>.
36 #include <sys/param.h>
38 #include <machine/segments.h>
39 #include <machine/sysarch.h>
56 * Process the special R_386_COPY relocations in the main program. These
57 * copy data from a shared object into a region in the main program's BSS
60 * Returns 0 on success, -1 on failure.
63 do_copy_relocations(Obj_Entry *dstobj)
65 const Elf_Rel *rellim;
68 assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
70 rellim = (const Elf_Rel *)((const char *)dstobj->rel + dstobj->relsize);
71 for (rel = dstobj->rel; rel < rellim; rel++) {
72 if (ELF_R_TYPE(rel->r_info) == R_386_COPY) {
74 const Elf_Sym *dstsym;
78 const Elf_Sym *srcsym;
79 const Obj_Entry *srcobj, *defobj;
83 dstaddr = (void *)(dstobj->relocbase + rel->r_offset);
84 dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info);
85 name = dstobj->strtab + dstsym->st_name;
86 size = dstsym->st_size;
87 symlook_init(&req, name);
88 req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rel->r_info));
89 req.flags = SYMLOOK_EARLY;
91 for (srcobj = globallist_next(dstobj); srcobj != NULL;
92 srcobj = globallist_next(srcobj)) {
93 res = symlook_obj(&req, srcobj);
96 defobj = req.defobj_out;
101 if (srcobj == NULL) {
102 _rtld_error("Undefined symbol \"%s\" referenced from COPY"
103 " relocation in %s", name, dstobj->path);
107 srcaddr = (const void *)(defobj->relocbase + srcsym->st_value);
108 memcpy(dstaddr, srcaddr, size);
115 /* Initialize the special GOT entries. */
117 init_pltgot(Obj_Entry *obj)
119 if (obj->pltgot != NULL) {
120 obj->pltgot[1] = (Elf_Addr) obj;
121 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
125 /* Process the non-PLT relocations. */
127 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags,
128 RtldLockState *lockstate)
130 const Elf_Rel *rellim;
134 const Obj_Entry *defobj;
135 Elf_Addr *where, symval, add;
140 * The dynamic loader may be called from a thread, we have
141 * limited amounts of stack available so we cannot use alloca().
143 if (obj != obj_rtld) {
144 cache = calloc(obj->dynsymcount, sizeof(SymCache));
145 /* No need to check for NULL here */
149 /* Appease some compilers. */
153 rellim = (const Elf_Rel *)((const char *)obj->rel + obj->relsize);
154 for (rel = obj->rel; rel < rellim; rel++) {
155 switch (ELF_R_TYPE(rel->r_info)) {
159 case R_386_TLS_TPOFF:
160 case R_386_TLS_TPOFF32:
161 case R_386_TLS_DTPMOD32:
162 case R_386_TLS_DTPOFF32:
163 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
164 flags, cache, lockstate);
167 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
168 switch (ELF_R_TYPE(rel->r_info)) {
172 if ((flags & SYMLOOK_IFUNC) == 0) {
173 obj->non_plt_gnu_ifunc = true;
176 symval = (Elf_Addr)rtld_resolve_ifunc(
179 case R_386_TLS_TPOFF:
180 case R_386_TLS_TPOFF32:
181 case R_386_TLS_DTPMOD32:
182 case R_386_TLS_DTPOFF32:
183 _rtld_error("%s: IFUNC for TLS reloc",
188 if ((flags & SYMLOOK_IFUNC) != 0)
190 symval = (Elf_Addr)defobj->relocbase +
195 if ((flags & SYMLOOK_IFUNC) != 0)
199 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
201 switch (ELF_R_TYPE(rel->r_info)) {
209 * I don't think the dynamic linker should ever
210 * see this type of relocation. But the
211 * binutils-2.6 tools sometimes generate it.
213 *where += symval - (Elf_Addr)where;
217 * These are deferred until all other
218 * relocations have been done. All we do here
219 * is make sure that the COPY relocation is
220 * not in a shared library. They are allowed
221 * only in executable files.
223 if (!obj->mainprog) {
224 _rtld_error("%s: Unexpected R_386_COPY "
225 "relocation in shared library", obj->path);
233 *where += (Elf_Addr)obj->relocbase;
235 case R_386_TLS_TPOFF:
236 case R_386_TLS_TPOFF32:
238 * We lazily allocate offsets for static TLS
239 * as we see the first relocation that
240 * references the TLS block. This allows us to
241 * support (small amounts of) static TLS in
242 * dynamically loaded modules. If we run out
243 * of space, we generate an error.
245 if (!defobj->tls_done) {
246 if (!allocate_tls_offset(
247 __DECONST(Obj_Entry *, defobj))) {
248 _rtld_error("%s: No space available "
249 "for static Thread Local Storage",
254 add = (Elf_Addr)(def->st_value - defobj->tlsoffset);
255 if (ELF_R_TYPE(rel->r_info) == R_386_TLS_TPOFF)
260 case R_386_TLS_DTPMOD32:
261 *where += (Elf_Addr)defobj->tlsindex;
263 case R_386_TLS_DTPOFF32:
264 *where += (Elf_Addr) def->st_value;
266 case R_386_IRELATIVE:
267 obj->irelative_nonplt = true;
270 _rtld_error("%s: Unsupported relocation type %d"
271 " in non-PLT relocations\n", obj->path,
272 ELF_R_TYPE(rel->r_info));
282 /* Process the PLT relocations. */
284 reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused)
286 const Elf_Rel *rellim;
289 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize);
290 for (rel = obj->pltrel; rel < rellim; rel++) {
291 Elf_Addr *where/*, val*/;
293 switch (ELF_R_TYPE(rel->r_info)) {
295 /* Relocate the GOT slot pointing into the PLT. */
296 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
297 *where += (Elf_Addr)obj->relocbase;
300 case R_386_IRELATIVE:
301 obj->irelative = true;
305 _rtld_error("Unknown relocation type %x in PLT",
306 ELF_R_TYPE(rel->r_info));
313 /* Relocate the jump slots in an object. */
315 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
317 const Elf_Rel *rellim;
320 if (obj->jmpslots_done)
322 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize);
323 for (rel = obj->pltrel; rel < rellim; rel++) {
324 Elf_Addr *where, target;
326 const Obj_Entry *defobj;
328 switch (ELF_R_TYPE(rel->r_info)) {
330 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
331 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
332 SYMLOOK_IN_PLT | flags, NULL, lockstate);
335 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
336 obj->gnu_ifunc = true;
339 target = (Elf_Addr)(defobj->relocbase + def->st_value);
340 reloc_jmpslot(where, target, defobj, obj, rel);
343 case R_386_IRELATIVE:
347 _rtld_error("Unknown relocation type %x in PLT",
348 ELF_R_TYPE(rel->r_info));
353 obj->jmpslots_done = true;
357 /* Fixup the jump slot at "where" to transfer control to "target". */
359 reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
360 const Obj_Entry *obj __unused, const Obj_Entry *refobj __unused,
361 const Elf_Rel *rel __unused)
364 dbg("reloc_jmpslot: *%p = %p", where, (void *)target);
372 reloc_iresolve_one(Obj_Entry *obj, const Elf_Rel *rel,
373 RtldLockState *lockstate)
375 Elf_Addr *where, target;
377 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
378 lock_release(rtld_bind_lock, lockstate);
379 target = call_ifunc_resolver(obj->relocbase + *where);
380 wlock_acquire(rtld_bind_lock, lockstate);
385 reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
387 const Elf_Rel *rellim;
392 obj->irelative = false;
393 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize);
394 for (rel = obj->pltrel; rel < rellim; rel++) {
395 if (ELF_R_TYPE(rel->r_info) == R_386_IRELATIVE)
396 reloc_iresolve_one(obj, rel, lockstate);
402 reloc_iresolve_nonplt(Obj_Entry *obj, RtldLockState *lockstate)
404 const Elf_Rel *rellim;
407 if (!obj->irelative_nonplt)
409 obj->irelative_nonplt = false;
410 rellim = (const Elf_Rel *)((const char *)obj->rel + obj->relsize);
411 for (rel = obj->rel; rel < rellim; rel++) {
412 if (ELF_R_TYPE(rel->r_info) == R_386_IRELATIVE)
413 reloc_iresolve_one(obj, rel, lockstate);
419 reloc_gnu_ifunc(Obj_Entry *obj, int flags, RtldLockState *lockstate)
421 const Elf_Rel *rellim;
426 rellim = (const Elf_Rel *)((const char *)obj->pltrel + obj->pltrelsize);
427 for (rel = obj->pltrel; rel < rellim; rel++) {
428 Elf_Addr *where, target;
430 const Obj_Entry *defobj;
432 switch (ELF_R_TYPE(rel->r_info)) {
434 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
435 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
436 SYMLOOK_IN_PLT | flags, NULL, lockstate);
439 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
441 lock_release(rtld_bind_lock, lockstate);
442 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
443 wlock_acquire(rtld_bind_lock, lockstate);
444 reloc_jmpslot(where, target, defobj, obj, rel);
449 obj->gnu_ifunc = false;
453 uint32_t cpu_feature, cpu_feature2, cpu_stdext_feature, cpu_stdext_feature2;
456 rtld_cpuid_count(int idx, int cnt, u_int *p)
464 : "=a" (p[0]), "=r" (p[1]), "=c" (p[2]), "=d" (p[3])
465 : "0" (idx), "2" (cnt));
469 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused)
471 u_int p[4], cpu_high;
477 " movl %%eax,%%ecx\n"
478 " xorl $0x200000,%%eax\n"
483 " xorl %%eax,%%ecx\n"
489 : "=r" (cpuid_supported) : : "eax", "ecx");
490 if (!cpuid_supported)
493 rtld_cpuid_count(1, 0, p);
496 rtld_cpuid_count(0, 0, p);
499 rtld_cpuid_count(7, 0, p);
500 cpu_stdext_feature = p[1];
501 cpu_stdext_feature2 = p[2];
512 allocate_initial_tls(Obj_Entry *objs)
517 * Fix the size of the static TLS block by using the maximum
518 * offset allocated so far and adding a bit for dynamic modules to
521 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
522 tls = allocate_tls(objs, NULL, 3*sizeof(Elf_Addr), sizeof(Elf_Addr));
523 i386_set_gsbase(tls);
527 __attribute__((__regparm__(1)))
528 void *___tls_get_addr(tls_index *ti)
532 __asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
534 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
538 void *__tls_get_addr(tls_index *ti)
542 __asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
544 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
548 calculate_first_tls_offset(size_t size, size_t align, size_t offset)
552 res = roundup(size, align);
555 res += align - offset;
560 calculate_tls_offset(size_t prev_offset, size_t prev_size __unused, size_t size,
561 size_t align, size_t offset)
565 res = roundup(prev_offset + size, align);
568 res += align - offset;
572 calculate_tls_end(size_t off, size_t size __unused)