/*- * Copyright 1996, 1997, 1998, 1999 John D. Polstra. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * $FreeBSD: src/libexec/rtld-elf/amd64/reloc.c,v 1.18.8.1 2009/04/15 03:14:26 kensmith Exp $ */ /* * Dynamic linker for ELF. * * John Polstra . */ #include #include #include #include #include #include #include #include #include #include #include #include #include "debug.h" #include "rtld.h" /* * Process the special R_X86_64_COPY relocations in the main program. These * copy data from a shared object into a region in the main program's BSS * segment. * * Returns 0 on success, -1 on failure. */ int do_copy_relocations(Obj_Entry *dstobj) { const Elf_Rela *relalim; const Elf_Rela *rela; assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */ relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela + dstobj->relasize); for (rela = dstobj->rela; rela < relalim; rela++) { if (ELF_R_TYPE(rela->r_info) == R_X86_64_COPY) { void *dstaddr; const Elf_Sym *dstsym; const char *name; unsigned long hash; size_t size; const void *srcaddr; const Elf_Sym *srcsym; Obj_Entry *srcobj; const Ver_Entry *ve; dstaddr = (void *) (dstobj->relocbase + rela->r_offset); dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info); name = dstobj->strtab + dstsym->st_name; hash = elf_hash(name); size = dstsym->st_size; ve = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info)); for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) if ((srcsym = symlook_obj(name, hash, srcobj, ve, 0)) != NULL) break; if (srcobj == NULL) { _rtld_error("Undefined symbol \"%s\" referenced from COPY" " relocation in %s", name, dstobj->path); return -1; } srcaddr = (const void *) (srcobj->relocbase + srcsym->st_value); memcpy(dstaddr, srcaddr, size); } } return 0; } /* Initialize the special GOT entries. */ void init_pltgot(Obj_Entry *obj) { if (obj->pltgot != NULL) { obj->pltgot[1] = (Elf_Addr) obj; obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start; } } /* Process the non-PLT relocations. */ int reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld) { const Elf_Rela *relalim; const Elf_Rela *rela; SymCache *cache; int bytes = obj->nchains * sizeof(SymCache); int r = -1; /* * The dynamic loader may be called from a thread, we have * limited amounts of stack available so we cannot use alloca(). */ int flags = obj->rtld_init ? MAP_LDSO : 0; cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON|flags, -1, 0); if (cache == MAP_FAILED) cache = NULL; relalim = (const Elf_Rela *) ((caddr_t) obj->rela + obj->relasize); for (rela = obj->rela; rela < relalim; rela++) { Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rela->r_offset); Elf32_Addr *where32 = (Elf32_Addr *)where; switch (ELF_R_TYPE(rela->r_info)) { case R_X86_64_NONE: break; case R_X86_64_64: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; *where = (Elf_Addr) (defobj->relocbase + def->st_value + rela->r_addend); } break; case R_X86_64_PC32: /* * I don't think the dynamic linker should ever see this * type of relocation. But the binutils-2.6 tools sometimes * generate it. */ { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; *where32 = (Elf32_Addr) (unsigned long) (defobj->relocbase + def->st_value + rela->r_addend - (Elf_Addr) where); } break; /* missing: R_X86_64_GOT32 R_X86_64_PLT32 */ case R_X86_64_COPY: /* * These are deferred until all other relocations have * been done. All we do here is make sure that the COPY * relocation is not in a shared library. They are allowed * only in executable files. */ if (!obj->mainprog) { _rtld_error("%s: Unexpected R_X86_64_COPY relocation" " in shared library", obj->path); goto done; } break; case R_X86_64_GLOB_DAT: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); /* cbass: Skip undefined symbols */ if (def == NULL || defobj == NULL) continue; *where = (Elf_Addr) (defobj->relocbase + def->st_value); } break; case R_X86_64_TPOFF64: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; /* * We lazily allocate offsets for static TLS as we * see the first relocation that references the * TLS block. This allows us to support (small * amounts of) static TLS in dynamically loaded * modules. If we run out of space, we generate an * error. */ if (!defobj->tls_done) { if (!allocate_tls_offset((Obj_Entry*) defobj)) { _rtld_error("%s: No space available for static " "Thread Local Storage", obj->path); goto done; } } *where = (Elf_Addr) (def->st_value - defobj->tlsoffset + rela->r_addend); } break; case R_X86_64_TPOFF32: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; /* * We lazily allocate offsets for static TLS as we * see the first relocation that references the * TLS block. This allows us to support (small * amounts of) static TLS in dynamically loaded * modules. If we run out of space, we generate an * error. */ if (!defobj->tls_done) { if (!allocate_tls_offset((Obj_Entry*) defobj)) { _rtld_error("%s: No space available for static " "Thread Local Storage", obj->path); goto done; } } *where32 = (Elf32_Addr) (def->st_value - defobj->tlsoffset + rela->r_addend); } break; case R_X86_64_DTPMOD64: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; *where += (Elf_Addr) defobj->tlsindex; } break; case R_X86_64_DTPOFF64: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; *where += (Elf_Addr) (def->st_value + rela->r_addend); } break; case R_X86_64_DTPOFF32: { const Elf_Sym *def; const Obj_Entry *defobj; def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, false, cache); if (def == NULL) goto done; *where32 += (Elf32_Addr) (def->st_value + rela->r_addend); } break; case R_X86_64_RELATIVE: *where = (Elf_Addr)(obj->relocbase + rela->r_addend); break; /* 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 */ default: _rtld_error("%s: Unsupported relocation type %u" " in non-PLT relocations\n", obj->path, (unsigned int)ELF_R_TYPE(rela->r_info)); goto done; } } r = 0; done: /* * Do not unmap if LDSO is in initialization, since some ctors might not * be called, yet. */ if (cache && !(obj->rtld_init)) munmap(cache, bytes); return(r); } /* Process the PLT relocations. */ int reloc_plt(Obj_Entry *obj) { const Elf_Rela *relalim; const Elf_Rela *rela; relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { Elf_Addr *where; assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT); /* Relocate the GOT slot pointing into the PLT. */ where = (Elf_Addr *)(obj->relocbase + rela->r_offset); *where += (Elf_Addr)obj->relocbase; } return 0; } /* Relocate the jump slots in an object. */ int reloc_jmpslots(Obj_Entry *obj) { const Elf_Rela *relalim; const Elf_Rela *rela; if (obj->jmpslots_done) return 0; relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize); for (rela = obj->pltrela; rela < relalim; rela++) { Elf_Addr *where, target; const Elf_Sym *def; const Obj_Entry *defobj; assert(ELF_R_TYPE(rela->r_info) == R_X86_64_JMP_SLOT); where = (Elf_Addr *)(obj->relocbase + rela->r_offset); def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true, NULL); if (def == NULL) return -1; target = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend); reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela); } obj->jmpslots_done = true; return 0; } void allocate_initial_tls(Obj_Entry *objs) { /* * Fix the size of the static TLS block by using the maximum * offset allocated so far and adding a bit for dynamic modules to * use. */ tls_static_space = tls_last_offset + RTLD_STATIC_TLS_EXTRA; amd64_set_fsbase(allocate_tls(objs, 0, 3*sizeof(Elf_Addr), sizeof(Elf_Addr))); } void *__tls_get_addr(tls_index *ti) { Elf_Addr** segbase; Elf_Addr* dtv; __asm __volatile("movq %%fs:0, %0" : "=r" (segbase)); dtv = segbase[1]; return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset); }