/* Elf relocation routines. Copyright 1996, 1997 Linux International. Contributed by Richard Henderson This file is part of the Linux modutils. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #ident "$Id: obj_reloc.c,v 1.2 1999/09/11 15:43:58 msw Exp $" #include #include #include #include #include /*======================================================================*/ int obj_string_patch(struct obj_file *f, int secidx, ElfW(Addr) offset, const char *string) { struct obj_string_patch_struct *p; struct obj_section *strsec; size_t len = strlen(string)+1; char *loc; p = xmalloc(sizeof(*p)); p->next = f->string_patches; p->reloc_secidx = secidx; p->reloc_offset = offset; f->string_patches = p; strsec = obj_find_section(f, ".kstrtab"); if (strsec == NULL) { strsec = obj_create_alloced_section(f, ".kstrtab", 1, len); p->string_offset = 0; loc = strsec->contents; } else { p->string_offset = strsec->header.sh_size; loc = obj_extend_section(strsec, len); } memcpy(loc, string, len); return 1; } int obj_symbol_patch(struct obj_file *f, int secidx, ElfW(Addr) offset, struct obj_symbol *sym) { struct obj_symbol_patch_struct *p; p = xmalloc(sizeof(*p)); p->next = f->symbol_patches; p->reloc_secidx = secidx; p->reloc_offset = offset; p->sym = sym; f->symbol_patches = p; return 1; } int obj_check_undefineds(struct obj_file *f) { unsigned long i; int ret = 1; for (i = 0; i < HASH_BUCKETS; ++i) { struct obj_symbol *sym; for (sym = f->symtab[i]; sym ; sym = sym->next) if (sym->secidx == SHN_UNDEF) { if (ELFW(ST_BIND)(sym->info) == STB_WEAK) { sym->secidx = SHN_ABS; sym->value = 0; } else { error("unresolved symbol %s", sym->name); ret = 0; } } } return ret; } void obj_allocate_commons(struct obj_file *f) { struct common_entry { struct common_entry *next; struct obj_symbol *sym; } *common_head = NULL; unsigned long i; for (i = 0; i < HASH_BUCKETS; ++i) { struct obj_symbol *sym; for (sym = f->symtab[i]; sym ; sym = sym->next) if (sym->secidx == SHN_COMMON) { /* Collect all COMMON symbols and sort them by size so as to minimize space wasted by alignment requirements. */ { struct common_entry **p, *n; for (p = &common_head; *p ; p = &(*p)->next) if (sym->size <= (*p)->sym->size) break; n = alloca(sizeof(*n)); n->next = *p; n->sym = sym; *p = n; } } } for (i = 1; i < f->local_symtab_size; ++i) { struct obj_symbol *sym = f->local_symtab[i]; if (sym && sym->secidx == SHN_COMMON) { struct common_entry **p, *n; for (p = &common_head; *p ; p = &(*p)->next) if (sym == (*p)->sym) break; else if (sym->size < (*p)->sym->size) { n = alloca(sizeof(*n)); n->next = *p; n->sym = sym; *p = n; break; } } } if (common_head) { /* Find the bss section. */ for (i = 0; i < f->header.e_shnum; ++i) if (f->sections[i]->header.sh_type == SHT_NOBITS) break; /* If for some reason there hadn't been one, create one. */ if (i == f->header.e_shnum) { struct obj_section *sec; f->sections = xrealloc(f->sections, (i+1) * sizeof(sec)); f->sections[i] = sec = arch_new_section(); f->header.e_shnum = i+1; memset(sec, 0, sizeof(*sec)); sec->header.sh_type = SHT_PROGBITS; sec->header.sh_flags = SHF_WRITE|SHF_ALLOC; sec->name = ".bss"; sec->idx = i; } /* Allocate the COMMONS. */ { ElfW(Addr) bss_size = f->sections[i]->header.sh_size; ElfW(Addr) max_align = f->sections[i]->header.sh_addralign; struct common_entry *c; for (c = common_head; c ; c = c->next) { ElfW(Addr) align = c->sym->value; if (align > max_align) max_align = align; if (bss_size & (align - 1)) bss_size = (bss_size | (align - 1)) + 1; c->sym->secidx = i; c->sym->value = bss_size; bss_size += c->sym->size; } f->sections[i]->header.sh_size = bss_size; f->sections[i]->header.sh_addralign = max_align; } } /* For the sake of patch relocation and parameter initialization, allocate zeroed data for NOBITS sections now. Note that after this we cannot assume NOBITS are really empty. */ for (i = 0; i < f->header.e_shnum; ++i) { struct obj_section *s = f->sections[i]; if (s->header.sh_type == SHT_NOBITS) { s->contents = memset(xmalloc(s->header.sh_size), 0, s->header.sh_size); s->header.sh_type = SHT_PROGBITS; } } } unsigned long obj_load_size (struct obj_file *f) { unsigned long dot = 0; struct obj_section *sec; /* Finalize the positions of the sections relative to one another. */ for (sec = f->load_order; sec ; sec = sec->load_next) { ElfW(Addr) align; align = sec->header.sh_addralign; if (align && (dot & (align - 1))) dot = (dot | (align - 1)) + 1; sec->header.sh_addr = dot; dot += sec->header.sh_size; } return dot; } int obj_relocate (struct obj_file *f, ElfW(Addr) base) { int i, n = f->header.e_shnum; int ret = 1; /* Finalize the addresses of the sections. */ f->baseaddr = base; for (i = 0; i < n; ++i) f->sections[i]->header.sh_addr += base; /* And iterate over all of the relocations. */ for (i = 0; i < n; ++i) { struct obj_section *relsec, *symsec, *targsec, *strsec; ElfW(RelM) *rel, *relend; ElfW(Sym) *symtab; const char *strtab; relsec = f->sections[i]; if (relsec->header.sh_type != SHT_RELM) continue; symsec = f->sections[relsec->header.sh_link]; targsec = f->sections[relsec->header.sh_info]; strsec = f->sections[symsec->header.sh_link]; rel = (ElfW(RelM) *)relsec->contents; relend = rel + (relsec->header.sh_size / sizeof(ElfW(RelM))); symtab = (ElfW(Sym) *)symsec->contents; strtab = (const char *)strsec->contents; for (; rel < relend; ++rel) { ElfW(Addr) value = 0; struct obj_symbol *intsym = NULL; unsigned long symndx; ElfW(Sym) *extsym = 0; const char *errmsg; /* Attempt to find a value to use for this relocation. */ symndx = ELFW(R_SYM)(rel->r_info); if (symndx) { /* Note we've already checked for undefined symbols. */ extsym = &symtab[symndx]; if (ELFW(ST_BIND)(extsym->st_info) == STB_LOCAL) { /* Local symbols we look up in the local table to be sure we get the one that is really intended. */ intsym = f->local_symtab[symndx]; } else { /* Others we look up in the hash table. */ const char *name; if (extsym->st_name) name = strtab + extsym->st_name; else name = f->sections[extsym->st_shndx]->name; intsym = obj_find_symbol(f, name); } value = obj_symbol_final_value(f, intsym); intsym->referenced = 1; } #if SHT_RELM == SHT_RELA #if defined(__alpha__) && defined(AXP_BROKEN_GAS) /* Work around a nasty GAS bug, that is fixed as of 2.7.0.9. */ if (!extsym || !extsym->st_name || ELFW(ST_BIND)(extsym->st_info) != STB_LOCAL) #endif value += rel->r_addend; #endif /* Do it! */ switch (arch_apply_relocation(f,targsec,symsec,intsym,rel,value)) { case obj_reloc_ok: break; case obj_reloc_overflow: errmsg = "Relocation overflow"; goto bad_reloc; case obj_reloc_dangerous: errmsg = "Dangerous relocation"; goto bad_reloc; case obj_reloc_unhandled: errmsg = "Unhandled relocation"; bad_reloc: if (extsym) { error("%s of type %ld for %s", errmsg, (long)ELFW(R_TYPE)(rel->r_info), strtab + extsym->st_name); } else { error("%s of type %ld", errmsg, (long)ELFW(R_TYPE)(rel->r_info)); } ret = 0; break; } } } /* Finally, take care of the patches. */ if (f->string_patches) { struct obj_string_patch_struct *p; struct obj_section *strsec; ElfW(Addr) strsec_base; strsec = obj_find_section(f, ".kstrtab"); strsec_base = strsec->header.sh_addr; for (p = f->string_patches; p ; p = p->next) { struct obj_section *targsec = f->sections[p->reloc_secidx]; *(ElfW(Addr) *)(targsec->contents + p->reloc_offset) = strsec_base + p->string_offset; } } if (f->symbol_patches) { struct obj_symbol_patch_struct *p; for (p = f->symbol_patches; p; p = p->next) { struct obj_section *targsec = f->sections[p->reloc_secidx]; *(ElfW(Addr) *)(targsec->contents + p->reloc_offset) = obj_symbol_final_value(f, p->sym); } } return ret; } int obj_create_image (struct obj_file *f, char *image) { struct obj_section *sec; ElfW(Addr) base = f->baseaddr; for (sec = f->load_order; sec ; sec = sec->load_next) { char *secimg; if (sec->header.sh_size == 0) continue; secimg = image + (sec->header.sh_addr - base); /* Note that we allocated data for NOBITS sections earlier. */ memcpy(secimg, sec->contents, sec->header.sh_size); } return 1; }