minix/libexec/ld.elf_so/arch/mips/mips_reloc.c

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/* $NetBSD: mips_reloc.c,v 1.60 2010/09/24 15:20:52 matt Exp $ */
/*
* Copyright 1997 Michael L. Hitch <mhitch@montana.edu>
* Portions copyright 2002 Charles M. Hannum <root@ihack.net>
* 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: mips_reloc.c,v 1.60 2010/09/24 15:20:52 matt Exp $");
#endif /* not lint */
#include <sys/types.h>
#include <sys/endian.h>
#include <stdlib.h>
#include <string.h>
#include "debug.h"
#include "rtld.h"
#ifdef __mips_o32
#define SUPPORT_OLD_BROKEN_LD
#endif
void _rtld_bind_start(void);
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
caddr_t _rtld_bind(Elf_Word, Elf_Addr, Elf_Addr, Elf_Addr);
/*
* It is possible for the compiler to emit relocations for unaligned data.
* We handle this situation with these inlines.
*/
#if ELFSIZE == 64
/*
* ELF64 MIPS encodes the relocs uniquely. The first 32-bits of info contain
* the symbol index. The top 32-bits contain three relocation types encoded
* in big-endian integer with first relocation in LSB. This means for little
* endian we have to byte swap that interger (r_type).
*/
#define Elf_Sxword Elf64_Sxword
#define ELF_R_NXTTYPE_64_P(r_type) ((((r_type) >> 8) & 0xff) == R_TYPE(64))
#if BYTE_ORDER == LITTLE_ENDIAN
#undef ELF_R_SYM
#undef ELF_R_TYPE
#define ELF_R_SYM(r_info) ((r_info) & 0xffffffff)
#define ELF_R_TYPE(r_info) bswap32((r_info) >> 32)
#endif
#else
#define ELF_R_NXTTYPE_64_P(r_type) (0)
#define Elf_Sxword Elf32_Sword
#endif
#define GOT1_MASK (~(Elf_Addr)0 >> 1)
static inline Elf_Sxword
load_ptr(void *where, size_t len)
{
Elf_Sxword val;
if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
#if ELFSIZE == 64
if (len == sizeof(Elf_Sxword))
return *(Elf_Sxword *)where;
#endif
return *(Elf_Sword *)where;
}
val = 0;
#if BYTE_ORDER == LITTLE_ENDIAN
(void)memcpy(&val, where, len);
#endif
#if BYTE_ORDER == BIG_ENDIAN
(void)memcpy((uint8_t *)((&val)+1) - len, where, len);
#endif
return (len == sizeof(Elf_Sxword)) ? val : (Elf_Sword)val;
}
static inline void
store_ptr(void *where, Elf_Sxword val, size_t len)
{
if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
#if ELFSIZE == 64
if (len == sizeof(Elf_Sxword)) {
*(Elf_Sxword *)where = val;
return;
}
#endif
*(Elf_Sword *)where = val;
return;
}
#if BYTE_ORDER == LITTLE_ENDIAN
(void)memcpy(where, &val, len);
#endif
#if BYTE_ORDER == BIG_ENDIAN
(void)memcpy(where, (const uint8_t *)((&val)+1) - len, len);
#endif
}
void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
/* XXX only if obj->pltgot[1] & 0x80000000 ?? */
obj->pltgot[1] |= (Elf_Addr) obj;
}
void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
const Elf_Rel *rel = 0, *rellim;
Elf_Addr relsz = 0;
void *where;
const Elf_Sym *symtab = NULL, *sym;
Elf_Addr *got = NULL;
Elf_Word local_gotno = 0, symtabno = 0, gotsym = 0;
size_t i;
for (; dynp->d_tag != DT_NULL; dynp++) {
switch (dynp->d_tag) {
case DT_REL:
rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
break;
case DT_RELSZ:
relsz = dynp->d_un.d_val;
break;
case DT_SYMTAB:
symtab = (const Elf_Sym *)(relocbase + dynp->d_un.d_ptr);
break;
case DT_PLTGOT:
got = (Elf_Addr *)(relocbase + dynp->d_un.d_ptr);
break;
case DT_MIPS_LOCAL_GOTNO:
local_gotno = dynp->d_un.d_val;
break;
case DT_MIPS_SYMTABNO:
symtabno = dynp->d_un.d_val;
break;
case DT_MIPS_GOTSYM:
gotsym = dynp->d_un.d_val;
break;
}
}
i = (got[1] & 0x80000000) ? 2 : 1;
/* Relocate the local GOT entries */
got += i;
for (; i < local_gotno; i++)
*got++ += relocbase;
sym = symtab + gotsym;
/* Now do the global GOT entries */
for (i = gotsym; i < symtabno; i++) {
*got = sym->st_value + relocbase;
++sym;
++got;
}
rellim = (const Elf_Rel *)((uintptr_t)rel + relsz);
for (; rel < rellim; rel++) {
Elf_Word r_symndx, r_type;
where = (void *)(relocbase + rel->r_offset);
r_symndx = ELF_R_SYM(rel->r_info);
r_type = ELF_R_TYPE(rel->r_info);
switch (r_type & 0xff) {
case R_TYPE(REL32): {
const size_t rlen =
ELF_R_NXTTYPE_64_P(r_type)
? sizeof(Elf_Sxword)
: sizeof(Elf_Sword);
Elf_Sxword old = load_ptr(where, rlen);
Elf_Sxword val = old;
#if ELFSIZE == 64
assert(r_type == R_TYPE(REL32)
|| r_type == (R_TYPE(REL32)|(R_TYPE(64) << 8)));
#endif
assert(r_symndx < gotsym);
sym = symtab + r_symndx;
assert(ELF_ST_BIND(sym->st_info) == STB_LOCAL);
val += relocbase;
store_ptr(where, val, sizeof(Elf_Sword));
rdbg(("REL32/L(%p) %p -> %p in <self>",
where, (void *)old, (void *)val));
store_ptr(where, val, rlen);
break;
}
case R_TYPE(GPREL32):
case R_TYPE(NONE):
break;
default:
abort();
}
}
}
int
_rtld_relocate_nonplt_objects(Obj_Entry *obj)
{
const Elf_Rel *rel;
Elf_Addr *got = obj->pltgot;
const Elf_Sym *sym, *def;
const Obj_Entry *defobj;
Elf_Word i;
#ifdef SUPPORT_OLD_BROKEN_LD
int broken;
#endif
#ifdef SUPPORT_OLD_BROKEN_LD
broken = 0;
sym = obj->symtab;
for (i = 1; i < 12; i++)
if (sym[i].st_info == ELF_ST_INFO(STB_LOCAL, STT_NOTYPE))
broken = 1;
dbg(("%s: broken=%d", obj->path, broken));
#endif
i = (got[1] & 0x80000000) ? 2 : 1;
/* Relocate the local GOT entries */
got += i;
for (; i < obj->local_gotno; i++)
*got++ += (Elf_Addr)obj->relocbase;
sym = obj->symtab + obj->gotsym;
/* Now do the global GOT entries */
for (i = obj->gotsym; i < obj->symtabno; i++) {
rdbg((" doing got %d sym %p (%s, %lx)", i - obj->gotsym, sym,
sym->st_name + obj->strtab, (u_long) *got));
#ifdef SUPPORT_OLD_BROKEN_LD
if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
broken && sym->st_shndx == SHN_UNDEF) {
/*
* XXX DANGER WILL ROBINSON!
* You might think this is stupid, as it intentionally
* defeats lazy binding -- and you'd be right.
* Unfortunately, for lazy binding to work right, we
* need to a way to force the GOT slots used for
* function pointers to be resolved immediately. This
* is supposed to be done automatically by the linker,
* by not outputting a PLT slot and setting st_value
* to 0 if there are non-PLT references, but older
* versions of GNU ld do not do this.
*/
def = _rtld_find_symdef(i, obj, &defobj, false);
if (def == NULL)
return -1;
*got = def->st_value + (Elf_Addr)defobj->relocbase;
} else
#endif
if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
sym->st_value != 0 && sym->st_shndx == SHN_UNDEF) {
/*
* If there are non-PLT references to the function,
* st_value should be 0, forcing us to resolve the
* address immediately.
*
* XXX DANGER WILL ROBINSON!
* The linker is not outputting PLT slots for calls to
* functions that are defined in the same shared
* library. This is a bug, because it can screw up
* link ordering rules if the symbol is defined in
* more than one module. For now, if there is a
* definition, we fail the test above and force a full
* symbol lookup. This means that all intra-module
* calls are bound immediately. - mycroft, 2003/09/24
*/
*got = sym->st_value + (Elf_Addr)obj->relocbase;
} else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) {
/* Symbols with index SHN_ABS are not relocated. */
if (sym->st_shndx != SHN_ABS)
*got = sym->st_value +
(Elf_Addr)obj->relocbase;
} else {
def = _rtld_find_symdef(i, obj, &defobj, false);
if (def == NULL)
return -1;
*got = def->st_value + (Elf_Addr)defobj->relocbase;
}
rdbg((" --> now %lx", (u_long) *got));
++sym;
++got;
}
got = obj->pltgot;
for (rel = obj->rel; rel < obj->rellim; rel++) {
Elf_Word r_symndx, r_type;
void *where;
where = obj->relocbase + rel->r_offset;
r_symndx = ELF_R_SYM(rel->r_info);
r_type = ELF_R_TYPE(rel->r_info);
switch (r_type & 0xff) {
case R_TYPE(NONE):
break;
case R_TYPE(REL32): {
/* 32-bit PC-relative reference */
const size_t rlen =
ELF_R_NXTTYPE_64_P(r_type)
? sizeof(Elf_Sxword)
: sizeof(Elf_Sword);
Elf_Sxword old = load_ptr(where, rlen);
Elf_Sxword val = old;
def = obj->symtab + r_symndx;
if (r_symndx >= obj->gotsym) {
val += got[obj->local_gotno + r_symndx - obj->gotsym];
rdbg(("REL32/G(%p) %p --> %p (%s) in %s",
where, (void *)old, (void *)val,
obj->strtab + def->st_name,
obj->path));
} else {
/*
* XXX: ABI DIFFERENCE!
*
* Old NetBSD binutils would generate shared
* libs with section-relative relocations being
* already adjusted for the start address of
* the section.
*
* New binutils, OTOH, generate shared libs
* with the same relocations being based at
* zero, so we need to add in the start address
* of the section.
*
* --rkb, Oct 6, 2001
*/
if (def->st_info ==
ELF_ST_INFO(STB_LOCAL, STT_SECTION)
#ifdef SUPPORT_OLD_BROKEN_LD
&& !broken
#endif
)
val += (Elf_Addr)def->st_value;
val += (Elf_Addr)obj->relocbase;
rdbg(("REL32/L(%p) %p -> %p (%s) in %s",
where, (void *)old, (void *)val,
obj->strtab + def->st_name, obj->path));
}
store_ptr(where, val, rlen);
break;
}
default:
rdbg(("sym = %lu, type = %lu, offset = %p, "
"contents = %p, symbol = %s",
(u_long)r_symndx, (u_long)ELF_R_TYPE(rel->r_info),
(void *)rel->r_offset,
(void *)load_ptr(where, sizeof(Elf_Sword)),
obj->strtab + obj->symtab[r_symndx].st_name));
_rtld_error("%s: Unsupported relocation type %ld "
"in non-PLT relocations",
obj->path, (u_long) ELF_R_TYPE(rel->r_info));
return -1;
}
}
return 0;
}
int
_rtld_relocate_plt_lazy(const Obj_Entry *obj)
{
/* PLT fixups were done above in the GOT relocation. */
return 0;
}
static inline int
_rtld_relocate_plt_object(const Obj_Entry *obj, Elf_Word sym, Elf_Addr *tp)
{
Elf_Addr *got = obj->pltgot;
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr new_value;
def = _rtld_find_plt_symdef(sym, obj, &defobj, tp != NULL);
if (__predict_false(def == NULL))
return -1;
if (__predict_false(def == &_rtld_sym_zero))
return 0;
new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
rdbg(("bind now/fixup in %s --> new=%p",
defobj->strtab + def->st_name, (void *)new_value));
got[obj->local_gotno + sym - obj->gotsym] = new_value;
if (tp)
*tp = new_value;
return 0;
}
caddr_t
_rtld_bind(Elf_Word a0, Elf_Addr a1, Elf_Addr a2, Elf_Addr a3)
{
Elf_Addr *got = (Elf_Addr *)(a2 - 0x7ff0);
const Obj_Entry *obj = (Obj_Entry *)(got[1] & GOT1_MASK);
Elf_Addr new_value = 0; /* XXX gcc */
int err;
err = _rtld_relocate_plt_object(obj, a0, &new_value);
if (err)
_rtld_die();
return (caddr_t)new_value;
}
int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
const Elf_Sym *sym = obj->symtab + obj->gotsym;
Elf_Word i;
for (i = obj->gotsym; i < obj->symtabno; i++, sym++) {
if (ELF_ST_TYPE(sym->st_info) == STT_FUNC)
if (_rtld_relocate_plt_object(obj, i, NULL) < 0)
return -1;
}
return 0;
}