492 lines
12 KiB
C
492 lines
12 KiB
C
/* $NetBSD: ppc_reloc.c,v 1.10 2001/09/10 06:09:41 mycroft Exp $ */
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/*-
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* Copyright (C) 1998 Tsubai Masanari
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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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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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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
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* OF 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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#include <sys/param.h>
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#include <sys/mman.h>
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#include <errno.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 <machine/cpu.h>
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#include "debug.h"
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#include "rtld.h"
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#define _ppc_ha(x) ((((u_int32_t)(x) & 0x8000) ? \
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((u_int32_t)(x) + 0x10000) : (u_int32_t)(x)) >> 16)
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#define _ppc_la(x) ((u_int32_t)(x) & 0xffff)
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/*
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* Process the R_PPC_COPY relocations
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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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/*
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* COPY relocs are invalid outside of the main program
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*/
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assert(dstobj->mainprog);
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relalim = (const Elf_Rela *) ((caddr_t) dstobj->rela +
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dstobj->relasize);
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for (rela = dstobj->rela; rela < relalim; rela++) {
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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 = NULL;
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Obj_Entry *srcobj;
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if (ELF_R_TYPE(rela->r_info) != R_PPC_COPY) {
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continue;
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}
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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;
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srcobj = srcobj->next) {
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if ((srcsym = symlook_obj(name, hash, srcobj, false))
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!= NULL) {
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break;
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}
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}
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if (srcobj == NULL) {
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_rtld_error("Undefined symbol \"%s\" "
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" 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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dbg("copy_reloc: src=%p,dst=%p,size=%d\n",srcaddr,dstaddr,size);
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}
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return (0);
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}
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/*
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* Perform early relocation of the run-time linker image
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*/
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void
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reloc_non_plt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
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{
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const Elf_Rela *rela = 0, *relalim;
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Elf_Addr relasz = 0;
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Elf_Addr *where;
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/*
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* Extract the rela/relasz values from the dynamic section
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*/
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for (; dynp->d_tag != DT_NULL; dynp++) {
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switch (dynp->d_tag) {
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case DT_RELA:
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rela = (const Elf_Rela *)(relocbase+dynp->d_un.d_ptr);
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break;
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case DT_RELASZ:
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relasz = dynp->d_un.d_val;
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break;
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}
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}
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/*
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* Relocate these values
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*/
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relalim = (const Elf_Rela *)((caddr_t)rela + relasz);
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for (; rela < relalim; rela++) {
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where = (Elf_Addr *)(relocbase + rela->r_offset);
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*where = (Elf_Addr)(relocbase + rela->r_addend);
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}
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}
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/*
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* Relocate a non-PLT object with addend.
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*/
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static int
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reloc_nonplt_object(Obj_Entry *obj_rtld, Obj_Entry *obj, const Elf_Rela *rela,
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SymCache *cache)
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{
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Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
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const Elf_Sym *def;
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const Obj_Entry *defobj;
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Elf_Addr tmp;
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switch (ELF_R_TYPE(rela->r_info)) {
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case R_PPC_NONE:
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break;
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case R_PPC_ADDR32: /* word32 S + A */
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case R_PPC_GLOB_DAT: /* word32 S + A */
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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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return (-1);
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}
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tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
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rela->r_addend);
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/* Don't issue write if unnecessary; avoid COW page fault */
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if (*where != tmp) {
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*where = tmp;
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}
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break;
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case R_PPC_RELATIVE: /* word32 B + A */
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tmp = (Elf_Addr)(obj->relocbase + rela->r_addend);
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/* As above, don't issue write unnecessarily */
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if (*where != tmp) {
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*where = tmp;
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}
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break;
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case R_PPC_COPY:
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/*
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* These are deferred until all other relocations
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* have been done. All we do here is make sure
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* that the COPY relocation is not in a shared
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* library. They are allowed only in executable
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* files.
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*/
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if (!obj->mainprog) {
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_rtld_error("%s: Unexpected R_COPY "
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" relocation in shared library",
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obj->path);
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return (-1);
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}
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break;
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case R_PPC_JMP_SLOT:
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/*
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* These will be handled by the plt/jmpslot routines
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*/
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break;
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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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return (-1);
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}
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return (0);
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}
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/*
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* Process non-PLT relocations
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*/
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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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/*
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* From the SVR4 PPC ABI:
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* "The PowerPC family uses only the Elf32_Rela relocation
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* entries with explicit addends."
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*/
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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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if (reloc_nonplt_object(obj_rtld, obj, rela, cache) < 0)
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goto done;
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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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}
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return (r);
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}
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/*
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* Initialise a PLT slot to the resolving trampoline
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*/
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static int
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reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela)
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{
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Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset);
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Elf_Addr *pltresolve;
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Elf_Addr distance;
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int reloff;
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reloff = rela - obj->pltrela;
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if ((reloff < 0) || (reloff >= 0x8000)) {
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return (-1);
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}
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pltresolve = obj->pltgot + 8;
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distance = (Elf_Addr)pltresolve - (Elf_Addr)(where + 1);
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dbg(" reloc_plt_object: where=%p,pltres=%p,reloff=%x,distance=%x",
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(void *)where, (void *)pltresolve, reloff, distance);
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/* li r11,reloff */
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/* b pltresolve */
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where[0] = 0x39600000 | reloff;
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where[1] = 0x48000000 | (distance & 0x03fffffc);
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/*
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* The icache will be sync'd in init_pltgot, which is called
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* after all the slots have been updated
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*/
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return (0);
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}
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/*
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* Process the PLT relocations.
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*/
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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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if (obj->pltrelasize != 0) {
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relalim = (const Elf_Rela *)((char *)obj->pltrela +
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obj->pltrelasize);
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for (rela = obj->pltrela; rela < relalim; rela++) {
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assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
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if (reloc_plt_object(obj, rela) < 0) {
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return (-1);
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}
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}
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}
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return (0);
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}
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/*
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* LD_BIND_NOW was set - force relocation for all jump slots
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*/
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int
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reloc_jmpslots(Obj_Entry *obj)
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{
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const Obj_Entry *defobj;
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const Elf_Rela *relalim;
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const Elf_Rela *rela;
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const Elf_Sym *def;
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Elf_Addr *where;
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Elf_Addr target;
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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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assert(ELF_R_TYPE(rela->r_info) == R_PPC_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,
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true, NULL);
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if (def == NULL) {
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dbg("reloc_jmpslots: sym not found");
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return (-1);
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}
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target = (Elf_Addr)(defobj->relocbase + def->st_value);
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#if 0
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/* PG XXX */
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dbg("\"%s\" in \"%s\" --> %p in \"%s\"",
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defobj->strtab + def->st_name, basename(obj->path),
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(void *)target, basename(defobj->path));
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#endif
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reloc_jmpslot(where, target, defobj, obj,
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(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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/*
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* Update the value of a PLT jump slot. Branch directly to the target if
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* it is within +/- 32Mb, otherwise go indirectly via the pltcall
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* trampoline call and jump table.
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*/
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Elf_Addr
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reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target, const Obj_Entry *defobj,
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const Obj_Entry *obj, const Elf_Rel *rel)
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{
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Elf_Addr offset;
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const Elf_Rela *rela = (const Elf_Rela *) rel;
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dbg(" reloc_jmpslot: where=%p, target=%p",
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(void *)wherep, (void *)target);
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/*
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* At the PLT entry pointed at by `wherep', construct
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* a direct transfer to the now fully resolved function
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* address.
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*/
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offset = target - (Elf_Addr)wherep;
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if (abs(offset) < 32*1024*1024) { /* inside 32MB? */
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/* b value # branch directly */
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*wherep = 0x48000000 | (offset & 0x03fffffc);
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__syncicache(wherep, 4);
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} else {
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Elf_Addr *pltcall, *jmptab;
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int distance;
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int N = obj->pltrelasize / sizeof(Elf_Rela);
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int reloff = rela - obj->pltrela;
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if ((reloff < 0) || (reloff >= 0x8000)) {
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return (-1);
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}
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pltcall = obj->pltgot;
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dbg(" reloc_jmpslot: indir, reloff=%d, N=%d\n",
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reloff, N);
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jmptab = obj->pltgot + 18 + N * 2;
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jmptab[reloff] = target;
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distance = (Elf_Addr)pltcall - (Elf_Addr)(wherep + 1);
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/* li r11,reloff */
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/* b pltcall # use indirect pltcall routine */
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wherep[0] = 0x39600000 | reloff;
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wherep[1] = 0x48000000 | (distance & 0x03fffffc);
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__syncicache(wherep, 8);
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}
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return (target);
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}
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/*
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* Setup the plt glue routines.
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*/
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#define PLTCALL_SIZE 20
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#define PLTRESOLVE_SIZE 24
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void
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init_pltgot(Obj_Entry *obj)
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{
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Elf_Word *pltcall, *pltresolve;
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Elf_Word *jmptab;
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int N = obj->pltrelasize / sizeof(Elf_Rela);
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pltcall = obj->pltgot;
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if (pltcall == NULL) {
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return;
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}
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/*
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* From the SVR4 PPC ABI:
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*
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* 'The first 18 words (72 bytes) of the PLT are reserved for
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* use by the dynamic linker.
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* ...
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* 'If the executable or shared object requires N procedure
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* linkage table entries, the link editor shall reserve 3*N
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* words (12*N bytes) following the 18 reserved words. The
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* first 2*N of these words are the procedure linkage table
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* entries themselves. The static linker directs calls to bytes
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* (72 + (i-1)*8), for i between 1 and N inclusive. The remaining
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* N words (4*N bytes) are reserved for use by the dynamic linker.'
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*/
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/*
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* Copy the absolute-call assembler stub into the first part of
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* the reserved PLT area.
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*/
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memcpy(pltcall, _rtld_powerpc_pltcall, PLTCALL_SIZE);
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/*
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* Determine the address of the jumptable, which is the dyn-linker
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* reserved area after the call cells. Write the absolute address
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* of the jumptable into the absolute-call assembler code so it
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* can determine this address.
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*/
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jmptab = pltcall + 18 + N * 2;
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pltcall[1] |= _ppc_ha(jmptab); /* addis 11,11,jmptab@ha */
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pltcall[2] |= _ppc_la(jmptab); /* lwz 11,jmptab@l(11) */
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/*
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* Skip down 32 bytes into the initial reserved area and copy
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* in the standard resolving assembler call. Into this assembler,
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* insert the absolute address of the _rtld_bind_start routine
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* and the address of the relocation object.
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*/
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pltresolve = obj->pltgot + 8;
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memcpy(pltresolve, _rtld_powerpc_pltresolve, PLTRESOLVE_SIZE);
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pltresolve[0] |= _ppc_ha(_rtld_bind_start);
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pltresolve[1] |= _ppc_la(_rtld_bind_start);
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pltresolve[3] |= _ppc_ha(obj);
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pltresolve[4] |= _ppc_la(obj);
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/*
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* Sync the icache for the byte range represented by the
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* trampoline routines and call slots.
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*/
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__syncicache(pltcall, 72 + N * 8);
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}
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