mirror/glibc
2
0
Fork 0
mirror of git://sourceware.org/git/glibc.git synced 2024-12-27 04:41:02 +08:00
Code Issues Packages Projects Releases Wiki Activity
7f3e75f87a
glibc/ports/sysdeps/arm/dl-machine.h

682 lines
20 KiB
C
Raw Blame History

/* Machine-dependent ELF dynamic relocation inline functions. ARM version.
Copyright (C) 1995-2013 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 "ARM"
#include <sys/param.h>
#include <tls.h>
#include <dl-tlsdesc.h>
#include <dl-irel.h>
#ifndef CLEAR_CACHE
# error CLEAR_CACHE definition required to handle TEXTREL
#endif
/* Return nonzero iff ELF header is compatible with the running host. */
static inline int __attribute__ ((unused))
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
return ehdr->e_machine == EM_ARM;
}
/* Return the link-time address of _DYNAMIC. Conveniently, this is the
first element of the GOT. We used to use the PIC register to do this
without a constant pool reference, but GCC 4.2 will use a pseudo-register
for the PIC base, so it may not be in r10. */
static inline Elf32_Addr __attribute__ ((unused))
elf_machine_dynamic (void)
{
Elf32_Addr dynamic;
#ifdef __thumb2__
long tmp;
asm ("ldr\t%0, 1f\n\t"
"adr\t%1, 1f\n\t"
"ldr\t%0, [%0, %1]\n\t"
"b 2f\n"
".align 2\n"
"1: .word _GLOBAL_OFFSET_TABLE_ - 1b\n"
"2:" : "=r" (dynamic), "=r"(tmp));
#else
asm ("ldr %0, 2f\n"
"1: ldr %0, [pc, %0]\n"
"b 3f\n"
"2: .word _GLOBAL_OFFSET_TABLE_ - (1b+8)\n"
"3:" : "=r" (dynamic));
#endif
return dynamic;
}
/* Return the run-time load address of the shared object. */
static inline Elf32_Addr __attribute__ ((unused))
elf_machine_load_address (void)
{
extern Elf32_Addr internal_function __dl_start (void *) asm ("_dl_start");
Elf32_Addr got_addr = (Elf32_Addr) &__dl_start;
Elf32_Addr pcrel_addr;
#ifdef __thumb__
/* Clear the low bit of the funciton address. */
got_addr &= ~(Elf32_Addr) 1;
#endif
asm ("adr %0, _dl_start" : "=r" (pcrel_addr));
return pcrel_addr - got_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__ ((unused))
elf_machine_runtime_setup (struct link_map *l, 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)
{
/* patb: this is different than i386 */
/* The GOT entries for functions in the PLT have not yet been filled
in. Their initial contents will arrange when called to push an
index into the .got section, load ip with &_GLOBAL_OFFSET_TABLE_[3],
and then jump to _GLOBAL_OFFSET_TABLE[2]. */
got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
/* If a library is prelinked but we have to relocate anyway,
we have to be able to undo the prelinking of .got.plt.
The prelinker saved us here address of .plt. */
if (got[1])
l->l_mach.plt = got[1] + l->l_addr;
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))
/* 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;
}
if (l->l_info[ADDRIDX (DT_TLSDESC_GOT)] && lazy)
*(Elf32_Addr*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_GOT)]) + l->l_addr)
= (Elf32_Addr) &_dl_tlsdesc_lazy_resolver;
return lazy;
}
#if defined(__USE_BX__)
#define BX(x) "bx\t" #x
#else
#define BX(x) "mov\tpc, " #x
#endif
/* Mask identifying addresses reserved for the user program,
where the dynamic linker should not map anything. */
#define ELF_MACHINE_USER_ADDRESS_MASK 0xf8000000UL
/* 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\
.globl _dl_start_user\n\
.type _dl_start_user, %function\n\
_start:\n\
@ we are PIC code, so get global offset table\n\
ldr sl, .L_GET_GOT\n\
@ See if we were run as a command with the executable file\n\
@ name as an extra leading argument.\n\
ldr r4, .L_SKIP_ARGS\n\
@ at start time, all the args are on the stack\n\
mov r0, sp\n\
bl _dl_start\n\
@ returns user entry point in r0\n\
_dl_start_user:\n\
adr r6, .L_GET_GOT\n\
add sl, sl, r6\n\
ldr r4, [sl, r4]\n\
@ save the entry point in another register\n\
mov r6, r0\n\
@ get the original arg count\n\
ldr r1, [sp]\n\
@ get the argv address\n\
add r2, sp, #4\n\
@ Fix up the stack if necessary.\n\
cmp r4, #0\n\
bne .L_fixup_stack\n\
.L_done_fixup:\n\
@ compute envp\n\
add r3, r2, r1, lsl #2\n\
add r3, r3, #4\n\
@ now we call _dl_init\n\
ldr r0, .L_LOADED\n\
ldr r0, [sl, r0]\n\
@ call _dl_init\n\
bl _dl_init_internal(PLT)\n\
@ load the finalizer function\n\
ldr r0, .L_FINI_PROC\n\
add r0, sl, r0\n\
@ jump to the user_s entry point\n\
" BX(r6) "\n\
\n\
@ iWMMXt and EABI targets require the stack to be eight byte\n\
@ aligned - shuffle arguments etc.\n\
.L_fixup_stack:\n\
@ subtract _dl_skip_args from original arg count\n\
sub r1, r1, r4\n\
@ store the new argc in the new stack location\n\
str r1, [sp]\n\
@ find the first unskipped argument\n\
mov r3, r2\n\
add r4, r2, r4, lsl #2\n\
@ shuffle argv down\n\
1: ldr r5, [r4], #4\n\
str r5, [r3], #4\n\
cmp r5, #0\n\
bne 1b\n\
@ shuffle envp down\n\
1: ldr r5, [r4], #4\n\
str r5, [r3], #4\n\
cmp r5, #0\n\
bne 1b\n\
@ shuffle auxv down\n\
1: ldmia r4!, {r0, r5}\n\
stmia r3!, {r0, r5}\n\
cmp r0, #0\n\
bne 1b\n\
@ Update _dl_argv\n\
ldr r3, .L_ARGV\n\
str r2, [sl, r3]\n\
b .L_done_fixup\n\
\n\
.L_GET_GOT:\n\
.word _GLOBAL_OFFSET_TABLE_ - .L_GET_GOT\n\
.L_SKIP_ARGS:\n\
.word _dl_skip_args(GOTOFF)\n\
.L_FINI_PROC:\n\
.word _dl_fini(GOTOFF)\n\
.L_ARGV:\n\
.word _dl_argv(GOTOFF)\n\
.L_LOADED:\n\
.word _rtld_local(GOTOFF)\n\
.previous\n\
");
/* 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_NOCOPY iff TYPE should not be allowed to resolve to one
of the main executable's symbols, as for a COPY reloc. */
#ifndef RTLD_BOOTSTRAP
# define elf_machine_type_class(type) \
((((type) == R_ARM_JUMP_SLOT || (type) == R_ARM_TLS_DTPMOD32 \
|| (type) == R_ARM_TLS_DTPOFF32 || (type) == R_ARM_TLS_TPOFF32 \
|| (type) == R_ARM_TLS_DESC) \
* ELF_RTYPE_CLASS_PLT) \
| (((type) == R_ARM_COPY) * ELF_RTYPE_CLASS_COPY))
#else
#define elf_machine_type_class(type) \
((((type) == R_ARM_JUMP_SLOT) * ELF_RTYPE_CLASS_PLT) \
| (((type) == R_ARM_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_ARM_JUMP_SLOT
/* ARM never uses Elf32_Rela relocations for the dynamic linker.
Prelinked libraries may use Elf32_Rela though. */
#define ELF_MACHINE_PLT_REL 1
/* We define an initialization functions. This is called very early in
_dl_sysdep_start. */
#define DL_PLATFORM_INIT dl_platform_init ()
static inline void __attribute__ ((unused))
dl_platform_init (void)
{
if (GLRO(dl_platform) != NULL && *GLRO(dl_platform) == '\0')
/* Avoid an empty string which would disturb us. */
GLRO(dl_platform) = NULL;
}
static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
const Elf32_Rel *reloc,
Elf32_Addr *reloc_addr, Elf32_Addr value)
{
return *reloc_addr = value;
}
/* Return the final value of a plt relocation. */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rel *reloc,
Elf32_Addr value)
{
return value;
}
#endif /* !dl_machine_h */
/* ARM never uses Elf32_Rela relocations for the dynamic linker.
Prelinked libraries may use Elf32_Rela though. */
#define ELF_MACHINE_NO_RELA defined RTLD_BOOTSTRAP
/* Names of the architecture-specific auditing callback functions. */
#define ARCH_LA_PLTENTER arm_gnu_pltenter
#define ARCH_LA_PLTEXIT arm_gnu_pltexit
#ifdef RESOLVE_MAP
/* Handle a PC24 reloc, including the out-of-range case. */
auto void
relocate_pc24 (struct link_map *map, Elf32_Addr value,
Elf32_Addr *const reloc_addr, Elf32_Sword addend)
{
Elf32_Addr new_value;
/* Set NEW_VALUE based on V, and return true iff it overflows 24 bits. */
inline bool set_new_value (Elf32_Addr v)
{
new_value = v + addend - (Elf32_Addr) reloc_addr;
Elf32_Addr topbits = new_value & 0xfe000000;
return topbits != 0xfe000000 && topbits != 0x00000000;
}
if (set_new_value (value))
{
/* The PC-relative address doesn't fit in 24 bits! */
static void *fix_page;
static size_t fix_offset;
if (fix_page == NULL)
{
void *new_page = __mmap (NULL, GLRO(dl_pagesize),
PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANON, -1, 0);
if (new_page == MAP_FAILED)
_dl_signal_error (0, map->l_name, NULL,
"could not map page for fixup");
fix_page = new_page;
assert (fix_offset == 0);
}
Elf32_Word *fix_address = fix_page + fix_offset;
fix_address[0] = 0xe51ff004; /* ldr pc, [pc, #-4] */
fix_address[1] = value;
fix_offset += sizeof fix_address[0] * 2;
if (fix_offset >= GLRO(dl_pagesize))
{
fix_page = NULL;
fix_offset = 0;
}
if (set_new_value ((Elf32_Addr) fix_address))
_dl_signal_error (0, map->l_name, NULL,
"R_ARM_PC24 relocation out of range");
}
*reloc_addr = (*reloc_addr & 0xff000000) | ((new_value >> 2) & 0x00ffffff);
}
/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
MAP is the object containing the reloc. */
auto inline void
__attribute__ ((always_inline))
elf_machine_rel (struct link_map *map, const Elf32_Rel *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 !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
if (__builtin_expect (r_type == R_ARM_RELATIVE, 0))
{
# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
/* This is defined in rtld.c, but nowhere in the static libc.a;
make the reference weak so static programs can still link.
This declaration cannot be done when compiling rtld.c
(i.e. #ifdef RTLD_BOOTSTRAP) because rtld.c contains the
common defn for _dl_rtld_map, which is incompatible with a
weak decl in the same file. */
# ifndef SHARED
weak_extern (_dl_rtld_map);
# endif
if (map != &GL(dl_rtld_map)) /* Already done in rtld itself. */
# endif
*reloc_addr += map->l_addr;
}
# ifndef RTLD_BOOTSTRAP
else if (__builtin_expect (r_type == R_ARM_NONE, 0))
return;
# endif
else
#endif
{
const Elf32_Sym *const refsym = sym;
struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
Elf32_Addr value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value;
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);
switch (r_type)
{
case R_ARM_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
|| (GLRO(dl_verbose) && sym->st_size < refsym->st_size))
{
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 ?: "<program name unknown>",
strtab + refsym->st_name);
}
memcpy (reloc_addr_arg, (void *) value,
MIN (sym->st_size, refsym->st_size));
break;
case R_ARM_GLOB_DAT:
case R_ARM_JUMP_SLOT:
# ifdef RTLD_BOOTSTRAP
/* Fix weak undefined references. */
if (sym != NULL && sym->st_value == 0)
*reloc_addr = 0;
else
# endif
*reloc_addr = value;
break;
case R_ARM_ABS32:
{
struct unaligned
{
Elf32_Addr x;
} __attribute__ ((packed, may_alias));
# ifndef RTLD_BOOTSTRAP
/* This is defined in rtld.c, but nowhere in the static
libc.a; make the reference weak so static programs can
still link. This declaration cannot be done when
compiling rtld.c (i.e. #ifdef RTLD_BOOTSTRAP) because
rtld.c contains the common defn for _dl_rtld_map, which
is incompatible with a weak decl in the same file. */
# ifndef SHARED
weak_extern (_dl_rtld_map);
# endif
if (map == &GL(dl_rtld_map))
/* Undo the relocation done here during bootstrapping.
Now we will relocate it anew, possibly using a
binding found in the user program or a loaded library
rather than the dynamic linker's built-in definitions
used while loading those libraries. */
value -= map->l_addr + refsym->st_value;
# endif
/* Support relocations on mis-aligned offsets. */
((struct unaligned *) reloc_addr)->x += value;
break;
}
case R_ARM_TLS_DESC:
{
struct tlsdesc volatile *td =
(struct tlsdesc volatile *)reloc_addr;
# ifndef RTLD_BOOTSTRAP
if (! sym)
td->entry = _dl_tlsdesc_undefweak;
else
# endif
{
value = sym->st_value + td->argument.value;
# ifndef RTLD_BOOTSTRAP
# ifndef SHARED
CHECK_STATIC_TLS (map, sym_map);
# else
if (!TRY_STATIC_TLS (map, sym_map))
{
td->argument.pointer
= _dl_make_tlsdesc_dynamic (sym_map, value);
td->entry = _dl_tlsdesc_dynamic;
}
else
# endif
# endif
{
td->argument.value = value + sym_map->l_tls_offset;
td->entry = _dl_tlsdesc_return;
}
}
}
break;
case R_ARM_PC24:
relocate_pc24 (map, value, reloc_addr,
/* Sign-extend the 24-bit addend in the
instruction (which counts instructions), and
then shift it up two so as to count bytes. */
(((Elf32_Sword) *reloc_addr << 8) >> 8) << 2);
break;
#if !defined RTLD_BOOTSTRAP
case R_ARM_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_ARM_TLS_DTPOFF32:
if (sym != NULL)
*reloc_addr += sym->st_value;
break;
case R_ARM_TLS_TPOFF32:
if (sym != NULL)
{
CHECK_STATIC_TLS (map, sym_map);
*reloc_addr += sym->st_value + sym_map->l_tls_offset;
}
break;
case R_ARM_IRELATIVE:
value = map->l_addr + *reloc_addr;
value = ((Elf32_Addr (*) (void)) value) ();
*reloc_addr = value;
break;
#endif
default:
_dl_reloc_bad_type (map, r_type, 0);
break;
}
}
}
# ifndef RTLD_BOOTSTRAP
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 unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
if (__builtin_expect (r_type == R_ARM_RELATIVE, 0))
*reloc_addr = map->l_addr + reloc->r_addend;
else if (__builtin_expect (r_type == R_ARM_NONE, 0))
return;
else
{
# ifndef RESOLVE_CONFLICT_FIND_MAP
const Elf32_Sym *const refsym = sym;
# endif
struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
Elf32_Addr value = sym_map == NULL ? 0 : sym_map->l_addr + sym->st_value;
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);
switch (r_type)
{
# ifndef RESOLVE_CONFLICT_FIND_MAP
/* Not needed for dl-conflict.c. */
case R_ARM_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
|| (GLRO(dl_verbose) && sym->st_size < refsym->st_size))
{
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 ?: "<program name unknown>",
strtab + refsym->st_name);
}
memcpy (reloc_addr_arg, (void *) value,
MIN (sym->st_size, refsym->st_size));
break;
# endif /* !RESOLVE_CONFLICT_FIND_MAP */
case R_ARM_GLOB_DAT:
case R_ARM_JUMP_SLOT:
case R_ARM_ABS32:
*reloc_addr = value + reloc->r_addend;
break;
case R_ARM_PC24:
relocate_pc24 (map, value, reloc_addr, reloc->r_addend);
break;
#if !defined RTLD_BOOTSTRAP
case R_ARM_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_ARM_TLS_DTPOFF32:
*reloc_addr = (sym == NULL ? 0 : sym->st_value) + reloc->r_addend;
break;
case R_ARM_TLS_TPOFF32:
if (sym != NULL)
{
CHECK_STATIC_TLS (map, sym_map);
*reloc_addr = (sym->st_value + sym_map->l_tls_offset
+ reloc->r_addend);
}
break;
case R_ARM_IRELATIVE:
value = map->l_addr + *reloc_addr;
value = ((Elf32_Addr (*) (void)) value) ();
*reloc_addr = value;
break;
#endif
default:
_dl_reloc_bad_type (map, r_type, 0);
break;
}
}
}
# endif
auto inline void
__attribute__ ((always_inline))
elf_machine_rel_relative (Elf32_Addr l_addr, const Elf32_Rel *reloc,
void *const reloc_addr_arg)
{
Elf32_Addr *const reloc_addr = reloc_addr_arg;
*reloc_addr += l_addr;
}
# ifndef RTLD_BOOTSTRAP
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;
}
# endif
auto inline void
__attribute__ ((always_inline))
elf_machine_lazy_rel (struct link_map *map,
Elf32_Addr l_addr, const Elf32_Rel *reloc,
int skip_ifunc)
{
Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
/* Check for unexpected PLT reloc type. */
if (__builtin_expect (r_type == R_ARM_JUMP_SLOT, 1))
{
if (__builtin_expect (map->l_mach.plt, 0) == 0)
*reloc_addr += l_addr;
else
*reloc_addr = map->l_mach.plt;
}
else if (__builtin_expect (r_type == R_ARM_TLS_DESC, 1))
{
struct tlsdesc volatile *td =
(struct tlsdesc volatile *)reloc_addr;
/* The linker must have given us the parameter we need in the
first GOT entry, and left the second one empty. We fill the
last with the resolver address */
assert (td->entry == 0);
td->entry = (void*)(D_PTR (map, l_info[ADDRIDX (DT_TLSDESC_PLT)])
+ map->l_addr);
}
else
_dl_reloc_bad_type (map, r_type, 1);
}
#endif /* RESOLVE_MAP */
Reference in New Issue View Git Blame Copy Permalink