/* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
Copyright (C) 1995-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#ifndef dl_machine_h
#define dl_machine_h
#define ELF_MACHINE_NAME "powerpc"
#include <assert.h>
#include <dl-tls.h>
#include <dl-irel.h>
#include <hwcapinfo.h>
/* Translate a processor specific dynamic tag to the index
in l_info array. */
#define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM)
/* Return nonzero iff ELF header is compatible with the running host. */
static inline int
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
return ehdr->e_machine == EM_PPC;
}
/* Return the value of the GOT pointer. */
static inline Elf32_Addr * __attribute__ ((const))
ppc_got (void)
{
Elf32_Addr *got;
asm ("bcl 20,31,1f\n"
"1: mflr %0\n"
" addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n"
" addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n"
: "=b" (got) : : "lr");
return got;
}
/* Return the link-time address of _DYNAMIC, stored as
the first value in the GOT. */
static inline Elf32_Addr __attribute__ ((const))
elf_machine_dynamic (void)
{
return *ppc_got ();
}
/* Return the run-time load address of the shared object. */
static inline Elf32_Addr __attribute__ ((const))
elf_machine_load_address (void)
{
Elf32_Addr *branchaddr;
Elf32_Addr runtime_dynamic;
/* This is much harder than you'd expect. Possibly I'm missing something.
The 'obvious' way:
Apparently, "bcl 20,31,$+4" is what should be used to load LR
with the address of the next instruction.
I think this is so that machines that do bl/blr pairing don't
get confused.
asm ("bcl 20,31,0f ;"
"0: mflr 0 ;"
"lis %0,0b@ha;"
"addi %0,%0,0b@l;"
"subf %0,%0,0"
: "=b" (addr) : : "r0", "lr");
doesn't work, because the linker doesn't have to (and in fact doesn't)
update the @ha and @l references; the loader (which runs after this
code) will do that.
Instead, we use the following trick:
The linker puts the _link-time_ address of _DYNAMIC at the first
word in the GOT. We could branch to that address, if we wanted,
by using an @local reloc; the linker works this out, so it's safe
to use now. We can't, of course, actually branch there, because
we'd cause an illegal instruction exception; so we need to compute
the address ourselves. That gives us the following code: */
/* Get address of the 'b _DYNAMIC@local'... */
asm ("bcl 20,31,0f;"
"b _DYNAMIC@local;"
"0:"
: "=l" (branchaddr));
/* So now work out the difference between where the branch actually points,
and the offset of that location in memory from the start of the file. */
runtime_dynamic = ((Elf32_Addr) branchaddr
+ ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6));
return runtime_dynamic - elf_machine_dynamic ();
}
#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */
/* The PLT uses Elf32_Rela relocs. */
#define elf_machine_relplt elf_machine_rela
/* Mask identifying addresses reserved for the user program,
where the dynamic linker should not map anything. */
#define ELF_MACHINE_USER_ADDRESS_MASK 0xf0000000UL
/* The actual _start code is in dl-start.S. Use a really
ugly bit of assembler to let dl-start.o see _dl_start. */
#define RTLD_START asm (".globl _dl_start");
/* Decide where a relocatable object should be loaded. */
extern ElfW(Addr)
__elf_preferred_address(struct link_map *loader, size_t maplength,
ElfW(Addr) mapstartpref);
#define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
__elf_preferred_address (loader, maplength, mapstartpref)
/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
PLT entries should not be allowed to define the value.
ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
of the main executable's symbols, as for a COPY reloc. */
/* We never want to use a PLT entry as the destination of a
reloc, when what is being relocated is a branch. This is
partly for efficiency, but mostly so we avoid loops. */
#define elf_machine_type_class(type) \
((((type) == R_PPC_JMP_SLOT \
|| (type) == R_PPC_REL24 \
|| ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */ \
&& (type) <= R_PPC_DTPREL32) \
|| (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \
| (((type) == R_PPC_COPY) * ELF_RTYPE_CLASS_COPY))
/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
#define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
/* The PowerPC never uses REL relocations. */
#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0
/* We define an initialization function to initialize HWCAP/HWCAP2 and
platform data so it can be copied into the TCB later. This is called
very early in _dl_sysdep_start for dynamically linked binaries. */
#ifdef SHARED
# define DL_PLATFORM_INIT dl_platform_init ()
static inline void __attribute__ ((unused))
dl_platform_init (void)
{
__tcb_parse_hwcap_and_convert_at_platform ();
}
#endif
/* Set up the loaded object described by MAP so its unrelocated PLT
entries will jump to the on-demand fixup code in dl-runtime.c.
Also install a small trampoline to be used by entries that have
been relocated to an address too far away for a single branch. */
extern int __elf_machine_runtime_setup (struct link_map *map,
int lazy, int profile);
static inline int
elf_machine_runtime_setup (struct link_map *map,
int lazy, int profile)
{
if (map->l_info[DT_JMPREL] == 0)
return lazy;
if (map->l_info[DT_PPC(GOT)] == 0)
/* Handle old style PLT. */
return __elf_machine_runtime_setup (map, lazy, profile);
/* New style non-exec PLT consisting of an array of addresses. */
map->l_info[DT_PPC(GOT)]->d_un.d_ptr += map->l_addr;
if (lazy)
{
Elf32_Addr *plt, *got, glink;
Elf32_Word num_plt_entries;
void (*dlrr) (void);
extern void _dl_runtime_resolve (void);
extern void _dl_prof_resolve (void);
if (__glibc_likely (!profile))
dlrr = _dl_runtime_resolve;
else
{
if (GLRO(dl_profile) != NULL
&&_dl_name_match_p (GLRO(dl_profile), map))
GL(dl_profile_map) = map;
dlrr = _dl_prof_resolve;
}
got = (Elf32_Addr *) map->l_info[DT_PPC(GOT)]->d_un.d_ptr;
glink = got[1];
got[1] = (Elf32_Addr) dlrr;
got[2] = (Elf32_Addr) map;
/* Relocate everything in .plt by the load address offset. */
plt = (Elf32_Addr *) D_PTR (map, l_info[DT_PLTGOT]);
num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
/ sizeof (Elf32_Rela));
/* If a library is prelinked but we have to relocate anyway,
we have to be able to undo the prelinking of .plt section.
The prelinker saved us at got[1] address of .glink
section's start. */
if (glink)
{
glink += map->l_addr;
while (num_plt_entries-- != 0)
*plt++ = glink, glink += 4;
}
else
while (num_plt_entries-- != 0)
*plt++ += map->l_addr;
}
return lazy;
}
/* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
Elf32_Addr *reloc_addr,
Elf32_Addr finaladdr);
static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
const Elf32_Rela *reloc,
Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
{
if (map->l_info[DT_PPC(GOT)] == 0)
/* Handle old style PLT. */
return __elf_machine_fixup_plt (map, reloc_addr, finaladdr);
*reloc_addr = finaladdr;
return finaladdr;
}
/* Return the final value of a plt relocation. */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
Elf32_Addr value)
{
return value + reloc->r_addend;
}
/* Names of the architecture-specific auditing callback functions. */
#define ARCH_LA_PLTENTER ppc32_gnu_pltenter
#define ARCH_LA_PLTEXIT ppc32_gnu_pltexit
#endif /* dl_machine_h */
#ifdef RESOLVE_MAP
/* Do the actual processing of a reloc, once its target address
has been determined. */
extern void __process_machine_rela (struct link_map *map,
const Elf32_Rela *reloc,
struct link_map *sym_map,
const Elf32_Sym *sym,
const Elf32_Sym *refsym,
Elf32_Addr *const reloc_addr,
Elf32_Addr finaladdr,
int rinfo) attribute_hidden;
/* Call _dl_signal_error when a resolved value overflows a relocated area. */
extern void _dl_reloc_overflow (struct link_map *map,
const char *name,
Elf32_Addr *const reloc_addr,
const Elf32_Sym *refsym) attribute_hidden;
/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
LOADADDR is the load address of the object; INFO is an array indexed
by DT_* of the .dynamic section info. */
auto inline void __attribute__ ((always_inline))
elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
const Elf32_Sym *sym, const struct r_found_version *version,
void *const reloc_addr_arg, int skip_ifunc)
{
Elf32_Addr *const reloc_addr = reloc_addr_arg;
const Elf32_Sym *const refsym = sym;
Elf32_Addr value;
const int r_type = ELF32_R_TYPE (reloc->r_info);
struct link_map *sym_map = NULL;
#ifndef RESOLVE_CONFLICT_FIND_MAP
if (r_type == R_PPC_RELATIVE)
{
*reloc_addr = map->l_addr + reloc->r_addend;
return;
}
if (__glibc_unlikely (r_type == R_PPC_NONE))
return;
/* binutils on ppc32 includes st_value in r_addend for relocations
against local symbols. */
if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0)
&& sym->st_shndx != SHN_UNDEF)
{
sym_map = map;
value = map->l_addr;
}
else
{
sym_map = RESOLVE_MAP (&sym, version, r_type);
value = SYMBOL_ADDRESS (sym_map, sym, true);
}
value += reloc->r_addend;
#else
value = reloc->r_addend;
#endif
if (sym != NULL
&& __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
&& __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
&& __builtin_expect (!skip_ifunc, 1))
value = elf_ifunc_invoke (value);
/* A small amount of code is duplicated here for speed. In libc,
more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
wouldn't usually handle). As an bonus, doing this here allows
the switch statement in __process_machine_rela to work. */
switch (r_type)
{
case R_PPC_GLOB_DAT:
case R_PPC_ADDR32:
*reloc_addr = value;
break;
#ifndef RESOLVE_CONFLICT_FIND_MAP
# ifdef RTLD_BOOTSTRAP
# define NOT_BOOTSTRAP 0
# else
# define NOT_BOOTSTRAP 1
# endif
case R_PPC_DTPMOD32:
if (map->l_info[DT_PPC(OPT)]
&& (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
{
if (!NOT_BOOTSTRAP)
{
reloc_addr[0] = 0;
reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
+ TLS_DTV_OFFSET);
break;
}
else if (sym_map != NULL)
{
# ifndef SHARED
CHECK_STATIC_TLS (map, sym_map);
# else
if (TRY_STATIC_TLS (map, sym_map))
# endif
{
reloc_addr[0] = 0;
/* Set up for local dynamic. */
reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
+ TLS_DTV_OFFSET);
break;
}
}
}
if (!NOT_BOOTSTRAP)
/* During startup the dynamic linker is always index 1. */
*reloc_addr = 1;
else if (sym_map != NULL)
/* Get the information from the link map returned by the
RESOLVE_MAP function. */
*reloc_addr = sym_map->l_tls_modid;
break;
case R_PPC_DTPREL32:
if (map->l_info[DT_PPC(OPT)]
&& (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
{
if (!NOT_BOOTSTRAP)
{
*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
break;
}
else if (sym_map != NULL)
{
/* This reloc is always preceded by R_PPC_DTPMOD32. */
# ifndef SHARED
assert (HAVE_STATIC_TLS (map, sym_map));
# else
if (HAVE_STATIC_TLS (map, sym_map))
# endif
{
*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
break;
}
}
}
/* During relocation all TLS symbols are defined and used.
Therefore the offset is already correct. */
if (NOT_BOOTSTRAP && sym_map != NULL)
*reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
break;
case R_PPC_TPREL32:
if (!NOT_BOOTSTRAP || sym_map != NULL)
{
if (NOT_BOOTSTRAP)
CHECK_STATIC_TLS (map, sym_map);
*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
}
break;
#endif
case R_PPC_JMP_SLOT:
#ifdef RESOLVE_CONFLICT_FIND_MAP
RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr);
#endif
if (map->l_info[DT_PPC(GOT)] != 0)
{
*reloc_addr = value;
break;
}
/* FALLTHROUGH */
default:
__process_machine_rela (map, reloc, sym_map, sym, refsym,
reloc_addr, value, r_type);
}
}
auto inline void __attribute__ ((always_inline))
elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
void *const reloc_addr_arg)
{
Elf32_Addr *const reloc_addr = reloc_addr_arg;
*reloc_addr = l_addr + reloc->r_addend;
}
auto inline void __attribute__ ((always_inline))
elf_machine_lazy_rel (struct link_map *map,
Elf32_Addr l_addr, const Elf32_Rela *reloc,
int skip_ifunc)
{
/* elf_machine_runtime_setup handles this. */
}
#endif /* RESOLVE_MAP */