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 *) ((caddr_t) 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 rellim = (const Elf_Rel *)((caddr_t) obj->rel + obj->relsize);
150 for (rel = obj->rel; rel < rellim; rel++) {
151 switch (ELF_R_TYPE(rel->r_info)) {
155 case R_386_TLS_TPOFF:
156 case R_386_TLS_TPOFF32:
157 case R_386_TLS_DTPMOD32:
158 case R_386_TLS_DTPOFF32:
159 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
160 flags, cache, lockstate);
163 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
164 switch (ELF_R_TYPE(rel->r_info)) {
168 if ((flags & SYMLOOK_IFUNC) == 0) {
169 obj->non_plt_gnu_ifunc = true;
172 symval = (Elf_Addr)rtld_resolve_ifunc(
175 case R_386_TLS_TPOFF:
176 case R_386_TLS_TPOFF32:
177 case R_386_TLS_DTPMOD32:
178 case R_386_TLS_DTPOFF32:
179 _rtld_error("%s: IFUNC for TLS reloc",
184 if ((flags & SYMLOOK_IFUNC) != 0)
186 symval = (Elf_Addr)defobj->relocbase +
191 if ((flags & SYMLOOK_IFUNC) != 0)
195 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
197 switch (ELF_R_TYPE(rel->r_info)) {
205 * I don't think the dynamic linker should ever
206 * see this type of relocation. But the
207 * binutils-2.6 tools sometimes generate it.
209 *where += symval - (Elf_Addr)where;
213 * These are deferred until all other
214 * relocations have been done. All we do here
215 * is make sure that the COPY relocation is
216 * not in a shared library. They are allowed
217 * only in executable files.
219 if (!obj->mainprog) {
220 _rtld_error("%s: Unexpected R_386_COPY "
221 "relocation in shared library", obj->path);
229 *where += (Elf_Addr)obj->relocbase;
231 case R_386_TLS_TPOFF:
232 case R_386_TLS_TPOFF32:
234 * We lazily allocate offsets for static TLS
235 * as we see the first relocation that
236 * references the TLS block. This allows us to
237 * support (small amounts of) static TLS in
238 * dynamically loaded modules. If we run out
239 * of space, we generate an error.
241 if (!defobj->tls_done) {
242 if (!allocate_tls_offset((Obj_Entry*) defobj)) {
243 _rtld_error("%s: No space available "
244 "for static Thread Local Storage",
249 add = (Elf_Addr)(def->st_value - defobj->tlsoffset);
250 if (ELF_R_TYPE(rel->r_info) == R_386_TLS_TPOFF)
255 case R_386_TLS_DTPMOD32:
256 *where += (Elf_Addr)defobj->tlsindex;
258 case R_386_TLS_DTPOFF32:
259 *where += (Elf_Addr) def->st_value;
262 _rtld_error("%s: Unsupported relocation type %d"
263 " in non-PLT relocations\n", obj->path,
264 ELF_R_TYPE(rel->r_info));
274 /* Process the PLT relocations. */
276 reloc_plt(Obj_Entry *obj)
278 const Elf_Rel *rellim;
281 rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
282 for (rel = obj->pltrel; rel < rellim; rel++) {
283 Elf_Addr *where/*, val*/;
285 switch (ELF_R_TYPE(rel->r_info)) {
287 /* Relocate the GOT slot pointing into the PLT. */
288 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
289 *where += (Elf_Addr)obj->relocbase;
292 case R_386_IRELATIVE:
293 obj->irelative = true;
297 _rtld_error("Unknown relocation type %x in PLT",
298 ELF_R_TYPE(rel->r_info));
305 /* Relocate the jump slots in an object. */
307 reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
309 const Elf_Rel *rellim;
312 if (obj->jmpslots_done)
314 rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
315 for (rel = obj->pltrel; rel < rellim; rel++) {
316 Elf_Addr *where, target;
318 const Obj_Entry *defobj;
320 switch (ELF_R_TYPE(rel->r_info)) {
322 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
323 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
324 SYMLOOK_IN_PLT | flags, NULL, lockstate);
327 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
328 obj->gnu_ifunc = true;
331 target = (Elf_Addr)(defobj->relocbase + def->st_value);
332 reloc_jmpslot(where, target, defobj, obj, rel);
335 case R_386_IRELATIVE:
339 _rtld_error("Unknown relocation type %x in PLT",
340 ELF_R_TYPE(rel->r_info));
345 obj->jmpslots_done = true;
349 /* Fixup the jump slot at "where" to transfer control to "target". */
351 reloc_jmpslot(Elf_Addr *where, Elf_Addr target,
352 const struct Struct_Obj_Entry *obj, const struct Struct_Obj_Entry *refobj,
356 dbg("reloc_jmpslot: *%p = %p", where, (void *)target);
364 reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
366 const Elf_Rel *rellim;
368 Elf_Addr *where, target;
372 rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
373 for (rel = obj->pltrel; rel < rellim; rel++) {
374 switch (ELF_R_TYPE(rel->r_info)) {
375 case R_386_IRELATIVE:
376 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
377 lock_release(rtld_bind_lock, lockstate);
378 target = call_ifunc_resolver(obj->relocbase + *where);
379 wlock_acquire(rtld_bind_lock, lockstate);
384 obj->irelative = false;
389 reloc_gnu_ifunc(Obj_Entry *obj, int flags, RtldLockState *lockstate)
391 const Elf_Rel *rellim;
396 rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
397 for (rel = obj->pltrel; rel < rellim; rel++) {
398 Elf_Addr *where, target;
400 const Obj_Entry *defobj;
402 switch (ELF_R_TYPE(rel->r_info)) {
404 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
405 def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
406 SYMLOOK_IN_PLT | flags, NULL, lockstate);
409 if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
411 lock_release(rtld_bind_lock, lockstate);
412 target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
413 wlock_acquire(rtld_bind_lock, lockstate);
414 reloc_jmpslot(where, target, defobj, obj, rel);
419 obj->gnu_ifunc = false;
423 uint32_t cpu_feature, cpu_feature2, cpu_stdext_feature, cpu_stdext_feature2;
426 rtld_cpuid_count(int idx, int cnt, u_int *p)
434 : "=a" (p[0]), "=r" (p[1]), "=c" (p[2]), "=d" (p[3])
435 : "0" (idx), "2" (cnt));
439 ifunc_init(Elf_Auxinfo aux_info[__min_size(AT_COUNT)] __unused)
441 u_int p[4], cpu_high;
447 " movl %%eax,%%ecx\n"
448 " xorl $0x200000,%%eax\n"
453 " xorl %%eax,%%ecx\n"
459 : "=r" (cpuid_supported) : : "eax", "ecx");
460 if (!cpuid_supported)
463 rtld_cpuid_count(1, 0, p);
466 rtld_cpuid_count(0, 0, p);
469 rtld_cpuid_count(7, 0, p);
470 cpu_stdext_feature = p[1];
471 cpu_stdext_feature2 = p[2];
476 allocate_initial_tls(Obj_Entry *objs)
481 * Fix the size of the static TLS block by using the maximum
482 * offset allocated so far and adding a bit for dynamic modules to
485 tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
486 tls = allocate_tls(objs, NULL, 3*sizeof(Elf_Addr), sizeof(Elf_Addr));
487 i386_set_gsbase(tls);
491 __attribute__((__regparm__(1)))
492 void *___tls_get_addr(tls_index *ti)
496 __asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
498 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
502 void *__tls_get_addr(tls_index *ti)
506 __asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
508 return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);