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glibc/sysdeps/powerpc/powerpc32/dl-machine.h

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/* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
Copyright (C) 1995-2002, 2003 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#ifndef dl_machine_h
#define dl_machine_h
#define ELF_MACHINE_NAME "powerpc"
#include <assert.h>
#include <dl-tls.h>
/* 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 link-time address of _DYNAMIC, stored as
the first value in the GOT. */
static inline Elf32_Addr
elf_machine_dynamic (void)
{
Elf32_Addr *got;
asm (" bl _GLOBAL_OFFSET_TABLE_-4@local"
: "=l"(got));
return *got;
}
/* Return the run-time load address of the shared object. */
static inline Elf32_Addr
elf_machine_load_address (void)
{
unsigned int *got;
unsigned int *branchaddr;
/* 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 ("bl 0f ;"
"b _DYNAMIC@local;"
"0:"
: "=l"(branchaddr));
/* ... and the address of the GOT. */
asm (" bl _GLOBAL_OFFSET_TABLE_-4@local"
: "=l"(got));
/* 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. */
return ((Elf32_Addr)branchaddr - *got
+ ((int)(*branchaddr << 6 & 0xffffff00) >> 6));
}
#define ELF_MACHINE_BEFORE_RTLD_RELOC(dynamic_info) /* nothing */
/* The PLT uses Elf32_Rela relocs. */
#define elf_machine_relplt elf_machine_rela
/* This code is used in dl-runtime.c to call the `fixup' function
and then redirect to the address it returns. It is called
from code built in the PLT by elf_machine_runtime_setup. */
#if !defined PROF
#define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\
.section \".text\" \n\
.align 2 \n\
.globl _dl_runtime_resolve \n\
.type _dl_runtime_resolve,@function \n\
_dl_runtime_resolve: \n\
# We need to save the registers used to pass parameters, and register 0,\n\
# which is used by _mcount; the registers are saved in a stack frame.\n\
stwu 1,-64(1) \n\
stw 0,12(1) \n\
stw 3,16(1) \n\
stw 4,20(1) \n\
# The code that calls this has put parameters for `fixup' in r12 and r11.\n\
mr 3,12 \n\
stw 5,24(1) \n\
mr 4,11 \n\
stw 6,28(1) \n\
mflr 0 \n\
# We also need to save some of the condition register fields.\n\
stw 7,32(1) \n\
stw 0,48(1) \n\
stw 8,36(1) \n\
mfcr 0 \n\
stw 9,40(1) \n\
stw 10,44(1) \n\
stw 0,8(1) \n\
bl fixup@local \n\
# 'fixup' returns the address we want to branch to.\n\
mtctr 3 \n\
# Put the registers back...\n\
lwz 0,48(1) \n\
lwz 10,44(1) \n\
lwz 9,40(1) \n\
mtlr 0 \n\
lwz 8,36(1) \n\
lwz 0,8(1) \n\
lwz 7,32(1) \n\
lwz 6,28(1) \n\
mtcrf 0xFF,0 \n\
lwz 5,24(1) \n\
lwz 4,20(1) \n\
lwz 3,16(1) \n\
lwz 0,12(1) \n\
# ...unwind the stack frame, and jump to the PLT entry we updated.\n\
addi 1,1,64 \n\
bctr \n\
.size _dl_runtime_resolve,.-_dl_runtime_resolve \n\
\n\
.align 2 \n\
.globl _dl_prof_resolve \n\
.type _dl_prof_resolve,@function \n\
_dl_prof_resolve: \n\
# We need to save the registers used to pass parameters, and register 0,\n\
# which is used by _mcount; the registers are saved in a stack frame.\n\
stwu 1,-64(1) \n\
stw 0,12(1) \n\
stw 3,16(1) \n\
stw 4,20(1) \n\
# The code that calls this has put parameters for `fixup' in r12 and r11.\n\
mr 3,12 \n\
stw 5,24(1) \n\
mr 4,11 \n\
stw 6,28(1) \n\
mflr 5 \n\
# We also need to save some of the condition register fields.\n\
stw 7,32(1) \n\
stw 5,48(1) \n\
stw 8,36(1) \n\
mfcr 0 \n\
stw 9,40(1) \n\
stw 10,44(1) \n\
stw 0,8(1) \n\
bl profile_fixup@local \n\
# 'fixup' returns the address we want to branch to.\n\
mtctr 3 \n\
# Put the registers back...\n\
lwz 0,48(1) \n\
lwz 10,44(1) \n\
lwz 9,40(1) \n\
mtlr 0 \n\
lwz 8,36(1) \n\
lwz 0,8(1) \n\
lwz 7,32(1) \n\
lwz 6,28(1) \n\
mtcrf 0xFF,0 \n\
lwz 5,24(1) \n\
lwz 4,20(1) \n\
lwz 3,16(1) \n\
lwz 0,12(1) \n\
# ...unwind the stack frame, and jump to the PLT entry we updated.\n\
addi 1,1,64 \n\
bctr \n\
.size _dl_prof_resolve,.-_dl_prof_resolve \n\
# Undo '.section text'.\n\
.previous \n\
");
#else
# define ELF_MACHINE_RUNTIME_TRAMPOLINE asm ("\n\
.section \".text\" \n\
.align 2 \n\
.globl _dl_runtime_resolve \n\
.globl _dl_prof_resolve \n\
.type _dl_runtime_resolve,@function \n\
.type _dl_prof_resolve,@function \n\
_dl_runtime_resolve: \n\
_dl_prof_resolve: \n\
# We need to save the registers used to pass parameters, and register 0,\n\
# which is used by _mcount; the registers are saved in a stack frame.\n\
stwu 1,-64(1) \n\
stw 0,12(1) \n\
stw 3,16(1) \n\
stw 4,20(1) \n\
# The code that calls this has put parameters for `fixup' in r12 and r11.\n\
mr 3,12 \n\
stw 5,24(1) \n\
mr 4,11 \n\
stw 6,28(1) \n\
mflr 0 \n\
# We also need to save some of the condition register fields.\n\
stw 7,32(1) \n\
stw 0,48(1) \n\
stw 8,36(1) \n\
mfcr 0 \n\
stw 9,40(1) \n\
stw 10,44(1) \n\
stw 0,8(1) \n\
bl fixup@local \n\
# 'fixup' returns the address we want to branch to.\n\
mtctr 3 \n\
# Put the registers back...\n\
lwz 0,48(1) \n\
lwz 10,44(1) \n\
lwz 9,40(1) \n\
mtlr 0 \n\
lwz 8,36(1) \n\
lwz 0,8(1) \n\
lwz 7,32(1) \n\
lwz 6,28(1) \n\
mtcrf 0xFF,0 \n\
lwz 5,24(1) \n\
lwz 4,20(1) \n\
lwz 3,16(1) \n\
lwz 0,12(1) \n\
# ...unwind the stack frame, and jump to the PLT entry we updated.\n\
addi 1,1,64 \n\
bctr \n\
.size _dl_runtime_resolve,.-_dl_runtime_resolve \n\
");
#endif
/* 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_NOCOPY 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. */
#if defined USE_TLS && (!defined RTLD_BOOTSTRAP || USE___THREAD)
#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))
#else
#define elf_machine_type_class(type) \
((((type) == R_PPC_JMP_SLOT \
|| (type) == R_PPC_REL24 \
|| (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \
| (((type) == R_PPC_COPY) * ELF_RTYPE_CLASS_COPY))
#endif
/* 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
/* Set up the loaded object described by L 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);
#define elf_machine_runtime_setup __elf_machine_runtime_setup
/* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
const Elf32_Rela *reloc,
Elf32_Addr *reloc_addr,
Elf32_Addr finaladdr);
static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
const Elf32_Rela *reloc,
Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
{
return __elf_machine_fixup_plt (map, reloc, reloc_addr, 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;
}
#endif /* dl_machine_h */
#ifdef RESOLVE
/* 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. */
inline void
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)
{
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 (__builtin_expect (r_type == R_PPC_NONE, 0))
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)
value = map->l_addr;
else
{
# if defined USE_TLS && !defined RTLD_BOOTSTRAP
sym_map = RESOLVE_MAP (&sym, version, r_type);
value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
# else
value = RESOLVE (&sym, version, r_type);
# ifndef RTLD_BOOTSTRAP
if (sym != NULL)
# endif
value += sym->st_value;
# endif
}
value += reloc->r_addend;
#else
value = reloc->r_addend;
#endif
/* 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;
#if defined USE_TLS && (!defined RTLD_BOOTSTRAP || USE___THREAD) \
&& !defined RESOLVE_CONFLICT_FIND_MAP
# ifdef RTLD_BOOTSTRAP
# define NOT_BOOTSTRAP 0
# else
# define NOT_BOOTSTRAP 1
# endif
case R_PPC_DTPMOD32:
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:
/* 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 /* USE_TLS etc. */
#ifdef RESOLVE_CONFLICT_FIND_MAP
case R_PPC_JMP_SLOT:
RESOLVE_CONFLICT_FIND_MAP (map, reloc_addr);
/* FALLTHROUGH */
#endif
default:
__process_machine_rela (map, reloc, sym_map, sym, refsym,
reloc_addr, value, r_type);
}
}
static inline void
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;
}
static inline void
elf_machine_lazy_rel (struct link_map *map,
Elf32_Addr l_addr, const Elf32_Rela *reloc)
{
/* elf_machine_runtime_setup handles this. */
}
/* The SVR4 ABI specifies that the JMPREL relocs must be inside the
DT_RELA table. */
#define ELF_MACHINE_PLTREL_OVERLAP 1
#endif /* RESOLVE */
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