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genode/repos/os/src/lib/ldso/contrib/amd64/reloc.c

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/*-
* 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 <jdp@polstra.com>.
*/
#include <sys/param.h>
#include <sys/mman.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_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);
}
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