NetBSD-5.0.2/libexec/ld.elf_so/arch/hppa/hppa_reloc.c
/* $NetBSD: hppa_reloc.c,v 1.27 2008/07/24 04:39:25 matt Exp $ */
/*-
* Copyright (c) 2002, 2004 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Matt Fredette and Nick Hudson.
*
* 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``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 FOUNDATION OR CONTRIBUTORS
* 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: hppa_reloc.c,v 1.27 2008/07/24 04:39:25 matt Exp $");
#endif /* not lint */
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/queue.h>
#include <string.h>
#include "rtld.h"
#include "debug.h"
#ifdef RTLD_DEBUG_HPPA
#define hdbg(x) xprintf x
#else
#define hdbg(x) /* nothing */
#endif
caddr_t _rtld_bind(const Obj_Entry *, const Elf_Addr);
void _rtld_bind_start(void);
void __rtld_setup_hppa_pltgot(const Obj_Entry *, Elf_Addr *);
/*
* It is possible for the compiler to emit relocations for unaligned data.
* We handle this situation with these inlines.
*/
#define RELOC_ALIGNED_P(x) \
(((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
static inline Elf_Addr
load_ptr(void *where)
{
if (__predict_true(RELOC_ALIGNED_P(where)))
return *(Elf_Addr *)where;
else {
Elf_Addr res;
(void)memcpy(&res, where, sizeof(res));
return res;
}
}
static inline void
store_ptr(void *where, Elf_Addr val)
{
if (__predict_true(RELOC_ALIGNED_P(where)))
*(Elf_Addr *)where = val;
else
(void)memcpy(where, &val, sizeof(val));
}
/*
* In the runtime architecture (ABI), PLABEL function
* pointers are distinguished from normal function
* pointers by having the next-least-significant bit
* set. (This bit is referred to as the L field in
* HP documentation). The $$dyncall millicode is
* aware of this.
*/
#define RTLD_MAKE_PLABEL(plabel) (((Elf_Addr)(plabel)) | (1 << 1))
#define RTLD_IS_PLABEL(addr) (((Elf_Addr)(addr)) & (1 << 1))
#define RTLD_GET_PLABEL(addr) ((hppa_plabel *) (((Elf_Addr)addr) & ~3))
/*
* This is the PLABEL structure. The function PC and
* shared linkage members must come first, as they are
* the actual PLABEL.
*/
typedef struct _hppa_plabel {
Elf_Addr hppa_plabel_pc;
Elf_Addr hppa_plabel_sl;
SLIST_ENTRY(_hppa_plabel) hppa_plabel_next;
} hppa_plabel;
/*
* For now allocated PLABEL structures are tracked on a
* singly linked list. This maybe should be revisited.
*/
static SLIST_HEAD(hppa_plabel_head, _hppa_plabel) hppa_plabel_list
= SLIST_HEAD_INITIALIZER(hppa_plabel_list);
/*
* Because I'm hesitant to use NEW while relocating self,
* this is a small pool of preallocated PLABELs.
*/
#define HPPA_PLABEL_PRE (12)
static hppa_plabel hppa_plabel_pre[HPPA_PLABEL_PRE];
static int hppa_plabel_pre_next = 0;
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
int _rtld_relocate_plt_objects(const Obj_Entry *);
static inline int _rtld_relocate_plt_object(const Obj_Entry *,
const Elf_Rela *, Elf_Addr *);
/*
* This bootstraps the dynamic linker by relocating its GOT.
* On the hppa, unlike on other architectures, static strings
* are found through the GOT. Static strings are essential
* for RTLD_DEBUG, and I suspect they're used early even when
* !defined(RTLD_DEBUG), making relocating the GOT essential.
*
* It gets worse. Relocating the GOT doesn't mean just walking
* it and adding the relocbase to all of the entries. You must
* find and use the GOT relocations, since those RELA relocations
* have the necessary addends - the GOT comes initialized as
* zeroes.
*/
void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
const Elf_Rela *relafirst, *rela, *relalim;
Elf_Addr relasz;
void *where;
Elf_Addr *pltgot;
const Elf_Rela *plabel_relocs[HPPA_PLABEL_PRE];
int nplabel_relocs = 0;
int i;
const Elf_Sym *symtab, *sym;
unsigned long symnum;
hppa_plabel *plabel;
/*
* Process the DYNAMIC section, looking for the non-PLT relocations.
*/
relafirst = NULL;
relasz = 0;
symtab = NULL;
pltgot = NULL;
for (; dynp->d_tag != DT_NULL; ++dynp) {
switch (dynp->d_tag) {
case DT_RELA:
relafirst = (const Elf_Rela *)
(relocbase + dynp->d_un.d_ptr);
break;
case DT_RELASZ:
relasz = dynp->d_un.d_val;
break;
case DT_SYMTAB:
symtab = (const Elf_Sym *)
(relocbase + dynp->d_un.d_ptr);
break;
case DT_PLTGOT:
pltgot = (Elf_Addr *)
(relocbase + dynp->d_un.d_ptr);
break;
}
}
relalim = (const Elf_Rela *)((caddr_t)relafirst + relasz);
for (rela = relafirst; rela < relalim; rela++) {
symnum = ELF_R_SYM(rela->r_info);
where = (void *)(relocbase + rela->r_offset);
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(DIR32):
if (symnum == 0)
store_ptr(where,
relocbase + rela->r_addend);
else {
sym = symtab + symnum;
store_ptr(where,
relocbase + rela->r_addend + sym->st_value);
}
break;
case R_TYPE(PLABEL32):
/*
* PLABEL32 relocation processing is done in two phases
*
* i) local function relocations (symbol number == 0)
* can be resolved immediately.
*
* ii) external function relocations are deferred until
* we finish all other relocations so that global
* data isn't accessed until all other non-PLT
* relocations have been done.
*/
if (symnum == 0)
*((Elf_Addr *)where) =
relocbase + rela->r_addend;
else
plabel_relocs[nplabel_relocs++] = rela;
break;
default:
break;
}
}
assert(nplabel_relocs < HPPA_PLABEL_PRE);
for (i = 0; i < nplabel_relocs; i++) {
rela = plabel_relocs[i];
where = (void *)(relocbase + rela->r_offset);
sym = symtab + ELF_R_SYM(rela->r_info);
plabel = &hppa_plabel_pre[hppa_plabel_pre_next++];
plabel->hppa_plabel_pc = (Elf_Addr)
(relocbase + sym->st_value + rela->r_addend);
plabel->hppa_plabel_sl = (Elf_Addr)pltgot;
SLIST_INSERT_HEAD(&hppa_plabel_list, plabel, hppa_plabel_next);
*((Elf_Addr *)where) = (Elf_Addr)(RTLD_MAKE_PLABEL(plabel));
}
#if defined(RTLD_DEBUG_HPPA)
for (rela = relafirst; rela < relalim; rela++) {
where = (void *)(relocbase + rela->r_offset);
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(DIR32):
hdbg(("DIR32 rela @%p(%p) -> %p(%p)\n",
(void *)rela->r_offset,
(void *)where,
(void *)rela->r_addend,
(void *)*((Elf_Addr *)where) ));
break;
case R_TYPE(PLABEL32):
symnum = ELF_R_SYM(rela->r_info);
if (symnum == 0) {
hdbg(("PLABEL rela @%p(%p) -> %p(%p)\n",
(void *)rela->r_offset,
(void *)where,
(void *)rela->r_addend,
(void *)*((Elf_Addr *)where) ));
} else {
sym = symtab + symnum;
hdbg(("PLABEL32 rela @%p(%p), symnum=%ld(%p) -> %p(%p)\n",
(void *)rela->r_offset,
(void *)where,
symnum,
(void *)sym->st_value,
(void *)rela->r_addend,
(void *)*((Elf_Addr *)where) ));
}
break;
default:
hdbg(("rela XXX reloc\n"));
break;
}
}
#endif /* RTLD_DEBUG_HPPA */
}
/*
* This allocates a PLABEL. If called with a non-NULL def, the
* plabel is for the function associated with that definition
* in the defining object defobj, plus the given addend. If
* called with a NULL def, the plabel is for the function at
* the (unrelocated) address in addend in the object defobj.
*/
Elf_Addr
_rtld_function_descriptor_alloc(const Obj_Entry *defobj, const Elf_Sym *def,
Elf_Addr addend)
{
Elf_Addr func_pc, func_sl;
hppa_plabel *plabel;
if (def != NULL) {
/*
* We assume that symbols of type STT_NOTYPE
* are undefined. Return NULL for these.
*/
if (ELF_ST_TYPE(def->st_info) == STT_NOTYPE)
return (Elf_Addr)NULL;
/* Otherwise assert that this symbol must be a function. */
assert(ELF_ST_TYPE(def->st_info) == STT_FUNC);
func_pc = (Elf_Addr)(defobj->relocbase + def->st_value +
addend);
} else
func_pc = (Elf_Addr)(defobj->relocbase + addend);
/*
* Search the existing PLABELs for one matching
* this function. If there is one, return it.
*/
func_sl = (Elf_Addr)(defobj->pltgot);
SLIST_FOREACH(plabel, &hppa_plabel_list, hppa_plabel_next)
if (plabel->hppa_plabel_pc == func_pc &&
plabel->hppa_plabel_sl == func_sl)
return RTLD_MAKE_PLABEL(plabel);
/*
* Once we've used up the preallocated set, we start
* using NEW to allocate plabels.
*/
if (hppa_plabel_pre_next < HPPA_PLABEL_PRE)
plabel = &hppa_plabel_pre[hppa_plabel_pre_next++];
else {
plabel = NEW(hppa_plabel);
if (plabel == NULL)
return (Elf_Addr)-1;
}
/* Fill the new entry and insert it on the list. */
plabel->hppa_plabel_pc = func_pc;
plabel->hppa_plabel_sl = func_sl;
SLIST_INSERT_HEAD(&hppa_plabel_list, plabel, hppa_plabel_next);
return RTLD_MAKE_PLABEL(plabel);
}
/*
* If a pointer is a PLABEL, this unwraps it.
*/
const void *
_rtld_function_descriptor_function(const void *addr)
{
return (RTLD_IS_PLABEL(addr) ?
(const void *) RTLD_GET_PLABEL(addr)->hppa_plabel_pc :
addr);
}
/* This sets up an object's GOT. */
void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
__rtld_setup_hppa_pltgot(obj, obj->pltgot);
}
int
_rtld_relocate_nonplt_objects(const Obj_Entry *obj)
{
const Elf_Rela *rela;
for (rela = obj->rela; rela < obj->relalim; rela++) {
Elf_Addr *where;
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr tmp;
unsigned long symnum;
where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
symnum = ELF_R_SYM(rela->r_info);
switch (ELF_R_TYPE(rela->r_info)) {
case R_TYPE(NONE):
break;
case R_TYPE(DIR32):
if (symnum) {
/*
* This is either a DIR32 against a symbol
* (def->st_name != 0), or against a local
* section (def->st_name == 0).
*/
def = obj->symtab + symnum;
defobj = obj;
if (def->st_name != 0)
def = _rtld_find_symdef(symnum, obj,
&defobj, false);
if (def == NULL)
return -1;
tmp = (Elf_Addr)(defobj->relocbase +
def->st_value + rela->r_addend);
if (load_ptr(where) != tmp)
store_ptr(where, tmp);
rdbg(("DIR32 %s in %s --> %p in %s",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)load_ptr(where), defobj->path));
} else {
tmp = (Elf_Addr)(obj->relocbase +
rela->r_addend);
if (load_ptr(where) != tmp)
store_ptr(where, tmp);
rdbg(("DIR32 in %s --> %p", obj->path,
(void *)load_ptr(where)));
}
break;
case R_TYPE(PLABEL32):
if (symnum) {
def = _rtld_find_symdef(symnum, obj, &defobj,
false);
if (def == NULL)
return -1;
tmp = _rtld_function_descriptor_alloc(defobj,
def, rela->r_addend);
if (tmp == (Elf_Addr)-1)
return -1;
if (*where != tmp)
*where = tmp;
rdbg(("PLABEL32 %s in %s --> %p in %s",
obj->strtab + obj->symtab[symnum].st_name,
obj->path, (void *)*where, defobj->path));
} else {
/*
* This is a PLABEL for a static function, and
* the dynamic linker has both allocated a PLT
* entry for this function and told us where it
* is. We can safely use the PLT entry as the
* PLABEL because there should be no other
* PLABEL reloc referencing this function.
* This object should also have an IPLT
* relocation to initialize the PLT entry.
*
* The dynamic linker should also have ensured
* that the addend has the
* next-least-significant bit set; the
* $$dyncall millicode uses this to distinguish
* a PLABEL pointer from a plain function
* pointer.
*/
tmp = (Elf_Addr)
(obj->relocbase + rela->r_addend);
if (*where != tmp)
*where = tmp;
rdbg(("PLABEL32 in %s --> %p", obj->path,
(void *)*where));
}
break;
case R_TYPE(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->isdynamic) {
_rtld_error(
"%s: Unexpected R_COPY relocation in shared library",
obj->path);
return -1;
}
rdbg(("COPY (avoid in main)"));
break;
default:
rdbg(("sym = %lu, type = %lu, offset = %p, "
"addend = %p, contents = %p, symbol = %s",
symnum, (u_long)ELF_R_TYPE(rela->r_info),
(void *)rela->r_offset, (void *)rela->r_addend,
(void *)load_ptr(where),
obj->strtab + obj->symtab[symnum].st_name));
_rtld_error("%s: Unsupported relocation type %ld "
"in non-PLT relocations\n",
obj->path, (u_long) ELF_R_TYPE(rela->r_info));
return -1;
}
}
return 0;
}
int
_rtld_relocate_plt_lazy(const Obj_Entry *obj)
{
const Elf_Rela *rela;
for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
Elf_Addr func_pc, func_sl;
assert(ELF_R_TYPE(rela->r_info) == R_TYPE(IPLT));
/*
* If this is an IPLT reloc for a static function,
* fully resolve the PLT entry now.
*/
if (ELF_R_SYM(rela->r_info) == 0) {
func_pc = (Elf_Addr)(obj->relocbase + rela->r_addend);
func_sl = (Elf_Addr)(obj->pltgot);
}
/*
* Otherwise set up for lazy binding.
*/
else {
/*
* This function pointer points to the PLT
* stub added by the linker, and instead of
* a shared linkage value, we stash this
* relocation's offset. The PLT stub has
* already been set up to transfer to
* _rtld_bind_start.
*/
func_pc = ((Elf_Addr)(obj->pltgot)) - 16;
func_sl = (Elf_Addr)
((caddr_t)rela - (caddr_t)(obj->pltrela));
}
rdbg(("lazy bind %s(%p) --> old=(%p,%p) new=(%p,%p)",
obj->path,
(void *)where,
(void *)where[0], (void *)where[1],
(void *)func_pc, (void *)func_sl));
/*
* Fill this PLT entry and return.
*/
where[0] = func_pc;
where[1] = func_sl;
}
return 0;
}
static inline int
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
{
Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset);
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr func_pc, func_sl;
assert(ELF_R_TYPE(rela->r_info) == R_TYPE(IPLT));
if (ELF_R_SYM(rela->r_info) == 0) {
func_pc = (Elf_Addr)(obj->relocbase + rela->r_addend);
func_sl = (Elf_Addr)(obj->pltgot);
} else {
def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true);
if (def == NULL)
return -1;
func_pc = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
func_sl = (Elf_Addr)(defobj->pltgot);
rdbg(("bind now/fixup in %s --> old=(%p,%p) new=(%p,%p)",
defobj->strtab + def->st_name,
(void *)where[0], (void *)where[1],
(void *)func_pc, (void *)func_sl));
}
/*
* Fill this PLT entry and return.
*/
if (where[0] != func_pc)
where[0] = func_pc;
if (where[1] != func_sl)
where[1] = func_sl;
if (tp)
*tp = (Elf_Addr)where;
return 0;
}
caddr_t
_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
{
const Elf_Rela *rela = (const Elf_Rela *)((caddr_t)obj->pltrela + reloff);
Elf_Addr new_value;
int err;
assert(ELF_R_SYM(rela->r_info) != 0);
err = _rtld_relocate_plt_object(obj, rela, &new_value);
if (err || new_value == 0)
_rtld_die();
return (caddr_t)new_value;
}
int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
const Elf_Rela *rela = obj->pltrela;
for (; rela < obj->pltrelalim; rela++) {
if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
return -1;
}
return 0;
}