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| Current File : //usr/src/libexec/rtld-elf/i386/reloc.c |
/*-
* 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: release/9.1.0/libexec/rtld-elf/i386/reloc.c 235396 2012-05-13 12:50:42Z kib $
*/
/*
* Dynamic linker for ELF.
*
* John Polstra <jdp@polstra.com>.
*/
#include <sys/param.h>
#include <sys/mman.h>
#include <machine/segments.h>
#include <machine/sysarch.h>
#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "debug.h"
#include "rtld.h"
/*
* Process the special R_386_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_Rel *rellim;
const Elf_Rel *rel;
assert(dstobj->mainprog); /* COPY relocations are invalid elsewhere */
rellim = (const Elf_Rel *) ((caddr_t) dstobj->rel + dstobj->relsize);
for (rel = dstobj->rel; rel < rellim; rel++) {
if (ELF_R_TYPE(rel->r_info) == R_386_COPY) {
void *dstaddr;
const Elf_Sym *dstsym;
const char *name;
size_t size;
const void *srcaddr;
const Elf_Sym *srcsym;
const Obj_Entry *srcobj, *defobj;
SymLook req;
int res;
dstaddr = (void *) (dstobj->relocbase + rel->r_offset);
dstsym = dstobj->symtab + ELF_R_SYM(rel->r_info);
name = dstobj->strtab + dstsym->st_name;
size = dstsym->st_size;
symlook_init(&req, name);
req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rel->r_info));
req.flags = SYMLOOK_EARLY;
for (srcobj = dstobj->next; srcobj != NULL; srcobj = srcobj->next) {
res = symlook_obj(&req, srcobj);
if (res == 0) {
srcsym = req.sym_out;
defobj = req.defobj_out;
break;
}
}
if (srcobj == NULL) {
_rtld_error("Undefined symbol \"%s\" referenced from COPY"
" relocation in %s", name, dstobj->path);
return -1;
}
srcaddr = (const void *) (defobj->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, int flags,
RtldLockState *lockstate)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
SymCache *cache;
int r = -1;
/*
* The dynamic loader may be called from a thread, we have
* limited amounts of stack available so we cannot use alloca().
*/
if (obj != obj_rtld) {
cache = calloc(obj->dynsymcount, sizeof(SymCache));
/* No need to check for NULL here */
} else
cache = NULL;
rellim = (const Elf_Rel *) ((caddr_t) obj->rel + obj->relsize);
for (rel = obj->rel; rel < rellim; rel++) {
Elf_Addr *where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
switch (ELF_R_TYPE(rel->r_info)) {
case R_386_NONE:
break;
case R_386_32:
{
const Elf_Sym *def;
const Obj_Entry *defobj;
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
flags, cache, lockstate);
if (def == NULL)
goto done;
*where += (Elf_Addr) (defobj->relocbase + def->st_value);
}
break;
case R_386_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(rel->r_info), obj, &defobj,
flags, cache, lockstate);
if (def == NULL)
goto done;
*where +=
(Elf_Addr) (defobj->relocbase + def->st_value) -
(Elf_Addr) where;
}
break;
case R_386_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_386_COPY relocation"
" in shared library", obj->path);
goto done;
}
break;
case R_386_GLOB_DAT:
{
const Elf_Sym *def;
const Obj_Entry *defobj;
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
flags, cache, lockstate);
if (def == NULL)
goto done;
*where = (Elf_Addr) (defobj->relocbase + def->st_value);
}
break;
case R_386_RELATIVE:
*where += (Elf_Addr) obj->relocbase;
break;
case R_386_TLS_TPOFF:
case R_386_TLS_TPOFF32:
{
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr add;
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
flags, cache, lockstate);
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;
}
}
add = (Elf_Addr) (def->st_value - defobj->tlsoffset);
if (ELF_R_TYPE(rel->r_info) == R_386_TLS_TPOFF)
*where += add;
else
*where -= add;
}
break;
case R_386_TLS_DTPMOD32:
{
const Elf_Sym *def;
const Obj_Entry *defobj;
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
flags, cache, lockstate);
if (def == NULL)
goto done;
*where += (Elf_Addr) defobj->tlsindex;
}
break;
case R_386_TLS_DTPOFF32:
{
const Elf_Sym *def;
const Obj_Entry *defobj;
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
flags, cache, lockstate);
if (def == NULL)
goto done;
*where += (Elf_Addr) def->st_value;
}
break;
default:
_rtld_error("%s: Unsupported relocation type %d"
" in non-PLT relocations\n", obj->path,
ELF_R_TYPE(rel->r_info));
goto done;
}
}
r = 0;
done:
if (cache != NULL)
free(cache);
return (r);
}
/* Process the PLT relocations. */
int
reloc_plt(Obj_Entry *obj)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
for (rel = obj->pltrel; rel < rellim; rel++) {
Elf_Addr *where/*, val*/;
switch (ELF_R_TYPE(rel->r_info)) {
case R_386_JMP_SLOT:
/* Relocate the GOT slot pointing into the PLT. */
where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
*where += (Elf_Addr)obj->relocbase;
break;
case R_386_IRELATIVE:
obj->irelative = true;
break;
default:
_rtld_error("Unknown relocation type %x in PLT",
ELF_R_TYPE(rel->r_info));
return (-1);
}
}
return 0;
}
/* Relocate the jump slots in an object. */
int
reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
if (obj->jmpslots_done)
return 0;
rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
for (rel = obj->pltrel; rel < rellim; rel++) {
Elf_Addr *where, target;
const Elf_Sym *def;
const Obj_Entry *defobj;
switch (ELF_R_TYPE(rel->r_info)) {
case R_386_JMP_SLOT:
where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
SYMLOOK_IN_PLT | flags, NULL, lockstate);
if (def == NULL)
return (-1);
if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
obj->gnu_ifunc = true;
continue;
}
target = (Elf_Addr)(defobj->relocbase + def->st_value);
reloc_jmpslot(where, target, defobj, obj, rel);
break;
case R_386_IRELATIVE:
break;
default:
_rtld_error("Unknown relocation type %x in PLT",
ELF_R_TYPE(rel->r_info));
return (-1);
}
}
obj->jmpslots_done = true;
return 0;
}
int
reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
Elf_Addr *where, target;
if (!obj->irelative)
return (0);
rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
for (rel = obj->pltrel; rel < rellim; rel++) {
switch (ELF_R_TYPE(rel->r_info)) {
case R_386_IRELATIVE:
where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
lock_release(rtld_bind_lock, lockstate);
target = ((Elf_Addr (*)(void))(obj->relocbase + *where))();
wlock_acquire(rtld_bind_lock, lockstate);
*where = target;
break;
}
}
obj->irelative = false;
return (0);
}
int
reloc_gnu_ifunc(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
const Elf_Rel *rellim;
const Elf_Rel *rel;
if (!obj->gnu_ifunc)
return (0);
rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
for (rel = obj->pltrel; rel < rellim; rel++) {
Elf_Addr *where, target;
const Elf_Sym *def;
const Obj_Entry *defobj;
switch (ELF_R_TYPE(rel->r_info)) {
case R_386_JMP_SLOT:
where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj,
SYMLOOK_IN_PLT | flags, NULL, lockstate);
if (def == NULL)
return (-1);
if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
continue;
lock_release(rtld_bind_lock, lockstate);
target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
wlock_acquire(rtld_bind_lock, lockstate);
reloc_jmpslot(where, target, defobj, obj, rel);
break;
}
}
obj->gnu_ifunc = false;
return (0);
}
void
allocate_initial_tls(Obj_Entry *objs)
{
void* tls;
/*
* 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;
tls = allocate_tls(objs, NULL, 3*sizeof(Elf_Addr), sizeof(Elf_Addr));
i386_set_gsbase(tls);
}
/* GNU ABI */
__attribute__((__regparm__(1)))
void *___tls_get_addr(tls_index *ti)
{
Elf_Addr** segbase;
Elf_Addr* dtv;
__asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
dtv = segbase[1];
return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
}
/* Sun ABI */
void *__tls_get_addr(tls_index *ti)
{
Elf_Addr** segbase;
Elf_Addr* dtv;
__asm __volatile("movl %%gs:0, %0" : "=r" (segbase));
dtv = segbase[1];
return tls_get_addr_common(&segbase[1], ti->ti_module, ti->ti_offset);
}