398 lines
10 KiB
C
398 lines
10 KiB
C
/*-
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* Copyright 1996, 1997, 1998, 1999 John D. Polstra.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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/*
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* Dynamic linker for ELF.
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*
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* John Polstra <jdp@polstra.com>.
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*/
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#include <sys/param.h>
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#include <sys/mman.h>
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#include <machine/sysarch.h>
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#include <dlfcn.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "debug.h"
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#include "rtld.h"
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/*
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* Process the special R_X86_64_COPY relocations in the main program. These
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* copy data from a shared object into a region in the main program's BSS
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* segment.
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*
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* Returns 0 on success, -1 on failure.
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*/
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int
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do_copy_relocations(Obj_Entry *dstobj)
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{
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
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relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize);
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for (rela = dstobj->rela; rela < relalim; rela++) {
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if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) {
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void *dstaddr;
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const Elf_Sym *dstsym;
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const char *name;
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unsigned long hash;
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size_t size;
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const void *srcaddr;
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const Elf_Sym *srcsym;
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Obj_Entry *srcobj;
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dstaddr = (void *) (dstobj->relocbase + rela->r_offset);
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dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
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name = dstobj->strtab + dstsym->st_name;
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hash = elf_hash(name);
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size = dstsym->st_size;
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for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next)
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if ((srcsym = symlook_obj(name, hash, srcobj, false)) != NULL)
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break;
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if (srcobj == NULL) {
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_rtld_error("Undefined symbol \"%s\" referenced from COPY"
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" relocation in %s", name, dstobj->path);
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return -1;
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}
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srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value);
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memcpy(dstaddr, srcaddr, size);
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}
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}
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return 0;
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}
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/* Initialize the special GOT entries. */
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void
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init_pltgot(Obj_Entry *obj)
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{
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if (obj->pltgot != NULL) {
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obj->pltgot[1] = (Elf_Addr) obj;
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obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
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}
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}
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/* Process the non-PLT relocations. */
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int
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reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
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{
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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SymCache *cache;
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int bytes = obj->nchains * sizeof(SymCache);
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int r = -1;
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/*
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* The dynamic loader may be called from a thread, we have
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* limited amounts of stack available so we cannot use alloca().
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*/
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cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
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if (cache == MAP_FAILED)
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cache = NULL;
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relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize);
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for (rela = obj->rela; rela < relalim; rela++) {
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Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
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Elf32_Addr *where32 = (Elf32_Addr *)where;
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switch (ELF_R_TYPE(rela->r_info)) {
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case R_X86_64_NONE:
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break;
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case R_X86_64_64:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend);
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}
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break;
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case R_X86_64_PC32:
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/*
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* I don't think the dynamic linker should ever see this
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* type of relocation. But the binutils-2.6 tools sometimes
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* generate it.
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*/
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase +
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def->st_value + rela->r_addend - (Elf_Addr) where);
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}
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break;
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/* missing: R_X86_64_GOT32 R_X86_64_PLT32 */
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case R_X86_64_COPY:
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/*
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* These are deferred until all other relocations have
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* been done. All we do here is make sure that the COPY
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* relocation is not in a shared library. They are allowed
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* only in executable files.
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*/
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if (!obj->mainprog) {
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_rtld_error("%s: Unexpected R_X86_64_COPY relocation"
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" in shared library", obj->path);
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goto done;
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}
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break;
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case R_X86_64_GLOB_DAT:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where = (Elf_Addr) (defobj->relocbase + def->st_value);
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}
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break;
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case R_X86_64_TPOFF64:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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/*
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* We lazily allocate offsets for static TLS as we
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* see the first relocation that references the
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* TLS block. This allows us to support (small
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* amounts of) static TLS in dynamically loaded
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* modules. If we run out of space, we generate an
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* error.
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*/
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if (!defobj->tls_done) {
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if (!allocate_tls_offset((Obj_Entry*) defobj)) {
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_rtld_error("%s: No space available for static "
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"Thread Local Storage", obj->path);
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goto done;
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}
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}
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*where = (Elf_Addr) (def->st_value - defobj->tlsoffset +
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rela->r_addend);
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}
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break;
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case R_X86_64_TPOFF32:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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/*
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* We lazily allocate offsets for static TLS as we
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* see the first relocation that references the
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* TLS block. This allows us to support (small
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* amounts of) static TLS in dynamically loaded
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* modules. If we run out of space, we generate an
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* error.
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*/
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if (!defobj->tls_done) {
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if (!allocate_tls_offset((Obj_Entry*) defobj)) {
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_rtld_error("%s: No space available for static "
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"Thread Local Storage", obj->path);
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goto done;
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}
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}
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*where32 = (Elf32_Addr) (def->st_value -
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defobj->tlsoffset +
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rela->r_addend);
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}
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break;
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case R_X86_64_DTPMOD64:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where += (Elf_Addr) defobj->tlsindex;
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}
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break;
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case R_X86_64_DTPOFF64:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where += (Elf_Addr) (def->st_value + rela->r_addend);
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}
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break;
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case R_X86_64_DTPOFF32:
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{
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
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false, cache);
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if (def == NULL)
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goto done;
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*where32 += (Elf32_Addr) (def->st_value + rela->r_addend);
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}
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break;
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case R_X86_64_RELATIVE:
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*where = (Elf_Addr)(obj->relocbase + rela->r_addend);
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break;
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/* missing: R_X86_64_GOTPCREL, R_X86_64_32, R_X86_64_32S, R_X86_64_16, R_X86_64_PC16, R_X86_64_8, R_X86_64_PC8 */
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default:
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_rtld_error("%s: Unsupported relocation type %d"
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" in non-PLT relocations\n", obj->path,
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ELF_R_TYPE(rela->r_info));
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goto done;
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}
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}
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r = 0;
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done:
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if (cache)
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munmap(cache, bytes);
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return(r);
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}
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/* Process the PLT relocations. */
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int
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reloc_plt(Obj_Entry *obj)
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{
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
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for (rela = obj->pltrela; rela < relalim; rela++) {
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Elf_Addr *where;
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assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
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/* Relocate the GOT slot pointing into the PLT. */
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where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
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*where += (Elf_Addr)obj->relocbase;
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}
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return 0;
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}
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/* Relocate the jump slots in an object. */
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int
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reloc_jmpslots(Obj_Entry *obj)
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{
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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if (obj->jmpslots_done)
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return 0;
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relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
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for (rela = obj->pltrela; rela < relalim; rela++) {
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Elf_Addr *where, target;
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT);
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where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
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def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL);
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if (def == NULL)
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return -1;
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target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
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reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela);
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}
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obj->jmpslots_done = true;
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return 0;
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}
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void
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allocate_initial_tls(Obj_Entry *objs)
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{
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/*
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* Fix the size of the static TLS block by using the maximum
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* offset allocated so far and adding a bit for dynamic modules to
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* use.
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*/
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tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA;
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amd64_set_fsbase(allocate_tls(objs, 0,
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2*sizeof(Elf_Addr), sizeof(Elf_Addr)));
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}
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void *__tls_get_addr(tls_index *ti)
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{
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Elf_Addr** segbase;
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Elf_Addr* dtv;
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__asm __volatile("movq %%fs:0, %0" : "=r" (segbase));
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dtv = segbase[1];
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return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
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}
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