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b19de59d62
glibc/sysdeps/m68k/dl-machine.h
Fangrui Song b19de59d62 elf: Avoid nested functions in the loader [BZ #27220] 
dynamic-link.h is included more than once in some elf/ files (rtld.c,
dl-conflict.c, dl-reloc.c, dl-reloc-static-pie.c) and uses GCC nested
functions. This harms readability and the nested functions usage
is the biggest obstacle prevents Clang build (Clang doesn't support GCC
nested functions).

The key idea for unnesting is to add extra parameters (struct link_map
*and struct r_scope_elm *[]) to RESOLVE_MAP,
ELF_MACHINE_BEFORE_RTLD_RELOC, ELF_DYNAMIC_RELOCATE, elf_machine_rel[a],
elf_machine_lazy_rel, and elf_machine_runtime_setup. (This is inspired
by Stan Shebs' ppc64/x86-64 implementation in the
google/grte/v5-2.27/master which uses mixed extra parameters and static
variables.)

Future simplification:
* If mips elf_machine_runtime_setup no longer needs RESOLVE_GOTSYM,
  elf_machine_runtime_setup can drop the `scope` parameter.
* If TLSDESC no longer need to be in elf_machine_lazy_rel,
  elf_machine_lazy_rel can drop the `scope` parameter.

Tested on aarch64, i386, x86-64, powerpc64le, powerpc64, powerpc32,
sparc64, sparcv9, s390x, s390, hppa, ia64, armhf, alpha, and mips64.
In addition, tested build-many-glibcs.py with {arc,csky,microblaze,nios2}-linux-gnu
and riscv64-linux-gnu-rv64imafdc-lp64d.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
(cherry picked from commit 490e6c62aa)
2022-04-08 14:18:11 -04:00

330 lines
10 KiB
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/* Machine-dependent ELF dynamic relocation inline functions. m68k version.
Copyright (C) 1996-2021 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
<https://www.gnu.org/licenses/>. */
#ifndef dl_machine_h
#define dl_machine_h
#define ELF_MACHINE_NAME "m68k"
#include <sys/param.h>
#include <sysdep.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_68K;
}
/* Return the link-time address of _DYNAMIC.
This must be inlined in a function which uses global data. */
static inline Elf32_Addr
elf_machine_dynamic (void)
{
Elf32_Addr addr;
asm ("move.l _DYNAMIC@GOT.w(%%a5), %0"
: "=a" (addr));
return addr;
}
/* Return the run-time load address of the shared object. */
static inline Elf32_Addr
elf_machine_load_address (void)
{
Elf32_Addr addr;
#ifdef SHARED
asm (PCREL_OP ("lea", "_dl_start", "%0", "%0", "%%pc") "\n\t"
"sub.l _dl_start@GOT.w(%%a5), %0"
: "=a" (addr));
#else
asm (PCREL_OP ("lea", "_dl_relocate_static_pie", "%0", "%0", "%%pc") "\n\t"
"sub.l _dl_relocate_static_pie@GOT.w(%%a5), %0"
: "=a" (addr));
#endif
return addr;
}
/* 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. */
static inline int __attribute__ ((always_inline))
elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
int lazy, int profile)
{
Elf32_Addr *got;
extern void _dl_runtime_resolve (Elf32_Word);
extern void _dl_runtime_profile (Elf32_Word);
if (l->l_info[DT_JMPREL] && lazy)
{
/* The GOT entries for functions in the PLT have not yet been
filled in. Their initial contents will arrange when called
to push an offset into the .rela.plt section, push
_GLOBAL_OFFSET_TABLE_[1], and then jump to
_GLOBAL_OFFSET_TABLE_[2]. */
got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
got[1] = (Elf32_Addr) l; /* Identify this shared object. */
/* The got[2] entry contains the address of a function which gets
called to get the address of a so far unresolved function and
jump to it. The profiling extension of the dynamic linker allows
to intercept the calls to collect information. In this case we
don't store the address in the GOT so that all future calls also
end in this function. */
if (profile)
{
got[2] = (Elf32_Addr) &_dl_runtime_profile;
if (GLRO(dl_profile) != NULL
&& _dl_name_match_p (GLRO(dl_profile), l))
{
/* This is the object we are looking for. Say that we really
want profiling and the timers are started. */
GL(dl_profile_map) = l;
}
}
else
/* This function will get called to fix up the GOT entry indicated by
the offset on the stack, and then jump to the resolved address. */
got[2] = (Elf32_Addr) &_dl_runtime_resolve;
}
return lazy;
}
#define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
#define ELF_MACHINE_RUNTIME_FIXUP_PARAMS save_a0, save_a1
/* Mask identifying addresses reserved for the user program,
where the dynamic linker should not map anything. */
#define ELF_MACHINE_USER_ADDRESS_MASK 0x80000000UL
/* Initial entry point code for the dynamic linker.
The C function `_dl_start' is the real entry point;
its return value is the user program's entry point. */
#define RTLD_START asm ("\
.text\n\
.globl _start\n\
.type _start,@function\n\
_start:\n\
sub.l %fp, %fp\n\
move.l %sp, -(%sp)\n\
jbsr _dl_start\n\
addq.l #4, %sp\n\
/* FALLTHRU */\n\
\n\
.globl _dl_start_user\n\
.type _dl_start_user,@function\n\
_dl_start_user:\n\
| Save the user entry point address in %a4.\n\
move.l %d0, %a4\n\
| See if we were run as a command with the executable file\n\
| name as an extra leading argument.\n\
" PCREL_OP ("move.l", "_dl_skip_args", "%d0", "%d0", "%pc") "\n\
| Pop the original argument count\n\
move.l (%sp)+, %d1\n\
| Subtract _dl_skip_args from it.\n\
sub.l %d0, %d1\n\
| Adjust the stack pointer to skip _dl_skip_args words.\n\
lea (%sp, %d0*4), %sp\n\
| Push back the modified argument count.\n\
move.l %d1, -(%sp)\n\
# Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
pea 8(%sp, %d1*4)\n\
pea 8(%sp)\n\
move.l %d1, -(%sp)\n\
" PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
jbsr _dl_init\n\
addq.l #8, %sp\n\
addq.l #8, %sp\n\
| Pass our finalizer function to the user in %a1.\n\
" PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
| Initialize %fp with the stack pointer.\n\
move.l %sp, %fp\n\
| Jump to the user's entry point.\n\
jmp (%a4)\n\
.size _dl_start_user, . - _dl_start_user\n\
.previous");
/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
TLS variable, so undefined references 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. */
#define elf_machine_type_class(type) \
((((type) == R_68K_JMP_SLOT \
|| (type) == R_68K_TLS_DTPMOD32 \
|| (type) == R_68K_TLS_DTPREL32 \
|| (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT) \
| (((type) == R_68K_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_68K_JMP_SLOT
/* The m68k never uses Elf32_Rel relocations. */
#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0
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, Elf32_Addr value)
{
return *reloc_addr = value;
}
/* Return the final value of a plt relocation. On the m68k the JMP_SLOT
relocation ignores the addend. */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
Elf32_Addr value)
{
return value;
}
/* Names of the architecture-specific auditing callback functions. */
#define ARCH_LA_PLTENTER m68k_gnu_pltenter
#define ARCH_LA_PLTEXIT m68k_gnu_pltexit
#endif /* !dl_machine_h */
#ifdef RESOLVE_MAP
/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
MAP is the object containing the reloc. */
static inline void __attribute__ ((unused, always_inline))
elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
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 unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
*reloc_addr = map->l_addr + reloc->r_addend;
else
{
const Elf32_Sym *const refsym = sym;
struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version,
r_type);
Elf32_Addr value = SYMBOL_ADDRESS (sym_map, sym, true);
switch (r_type)
{
case R_68K_COPY:
if (sym == NULL)
/* This can happen in trace mode if an object could not be
found. */
break;
if (sym->st_size > refsym->st_size
|| (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
{
const char *strtab;
strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
_dl_error_printf ("\
%s: Symbol `%s' has different size in shared object, consider re-linking\n",
RTLD_PROGNAME, strtab + refsym->st_name);
}
memcpy (reloc_addr_arg, (void *) value,
MIN (sym->st_size, refsym->st_size));
break;
case R_68K_GLOB_DAT:
case R_68K_JMP_SLOT:
*reloc_addr = value;
break;
case R_68K_8:
*(char *) reloc_addr = value + reloc->r_addend;
break;
case R_68K_16:
*(short *) reloc_addr = value + reloc->r_addend;
break;
case R_68K_32:
*reloc_addr = value + reloc->r_addend;
break;
case R_68K_PC8:
*(char *) reloc_addr
= value + reloc->r_addend - (Elf32_Addr) reloc_addr;
break;
case R_68K_PC16:
*(short *) reloc_addr
= value + reloc->r_addend - (Elf32_Addr) reloc_addr;
break;
case R_68K_PC32:
*reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
break;
#ifndef RTLD_BOOTSTRAP
case R_68K_TLS_DTPMOD32:
/* Get the information from the link map returned by the
resolv function. */
if (sym_map != NULL)
*reloc_addr = sym_map->l_tls_modid;
break;
case R_68K_TLS_DTPREL32:
if (sym != NULL)
*reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
break;
case R_68K_TLS_TPREL32:
if (sym != NULL)
{
CHECK_STATIC_TLS (map, sym_map);
*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
}
break;
#endif /* !RTLD_BOOTSTRAP */
case R_68K_NONE: /* Alright, Wilbur. */
break;
default:
_dl_reloc_bad_type (map, r_type, 0);
break;
}
}
}
static inline void __attribute__ ((unused, 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;
}
static inline void __attribute__ ((unused, always_inline))
elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
Elf32_Addr l_addr, const Elf32_Rela *reloc,
int skip_ifunc)
{
Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
*reloc_addr += l_addr;
else
_dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
}
#endif /* RESOLVE_MAP */
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