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b19de59d62
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
)
377 lines
12 KiB
C
377 lines
12 KiB
C
/* Relocate a shared object and resolve its references to other loaded objects.
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Copyright (C) 1995-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <libintl.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <ldsodefs.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <sys/types.h>
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#include <_itoa.h>
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#include <libc-pointer-arith.h>
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#include "dynamic-link.h"
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/* Statistics function. */
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#ifdef SHARED
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# define bump_num_cache_relocations() ++GL(dl_num_cache_relocations)
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#else
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# define bump_num_cache_relocations() ((void) 0)
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#endif
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/* We are trying to perform a static TLS relocation in MAP, but it was
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dynamically loaded. This can only work if there is enough surplus in
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the static TLS area already allocated for each running thread. If this
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object's TLS segment is too big to fit, we fail with -1. If it fits,
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we set MAP->l_tls_offset and return 0.
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A portion of the surplus static TLS can be optionally used to optimize
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dynamic TLS access (with TLSDESC or powerpc TLS optimizations).
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If OPTIONAL is true then TLS is allocated for such optimization and
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the caller must have a fallback in case the optional portion of surplus
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TLS runs out. If OPTIONAL is false then the entire surplus TLS area is
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considered and the allocation only fails if that runs out. */
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int
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_dl_try_allocate_static_tls (struct link_map *map, bool optional)
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{
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/* If we've already used the variable with dynamic access, or if the
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alignment requirements are too high, fail. */
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if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET
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|| map->l_tls_align > GLRO (dl_tls_static_align))
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{
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fail:
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return -1;
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}
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#if TLS_TCB_AT_TP
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size_t freebytes = GLRO (dl_tls_static_size) - GL(dl_tls_static_used);
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if (freebytes < TLS_TCB_SIZE)
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goto fail;
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freebytes -= TLS_TCB_SIZE;
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size_t blsize = map->l_tls_blocksize + map->l_tls_firstbyte_offset;
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if (freebytes < blsize)
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goto fail;
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size_t n = (freebytes - blsize) / map->l_tls_align;
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/* Account optional static TLS surplus usage. */
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size_t use = freebytes - n * map->l_tls_align - map->l_tls_firstbyte_offset;
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if (optional && use > GL(dl_tls_static_optional))
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goto fail;
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else if (optional)
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GL(dl_tls_static_optional) -= use;
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size_t offset = GL(dl_tls_static_used) + use;
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map->l_tls_offset = GL(dl_tls_static_used) = offset;
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#elif TLS_DTV_AT_TP
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/* dl_tls_static_used includes the TCB at the beginning. */
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size_t offset = (ALIGN_UP(GL(dl_tls_static_used)
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- map->l_tls_firstbyte_offset,
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map->l_tls_align)
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+ map->l_tls_firstbyte_offset);
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size_t used = offset + map->l_tls_blocksize;
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if (used > GLRO (dl_tls_static_size))
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goto fail;
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/* Account optional static TLS surplus usage. */
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size_t use = used - GL(dl_tls_static_used);
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if (optional && use > GL(dl_tls_static_optional))
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goto fail;
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else if (optional)
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GL(dl_tls_static_optional) -= use;
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map->l_tls_offset = offset;
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map->l_tls_firstbyte_offset = GL(dl_tls_static_used);
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GL(dl_tls_static_used) = used;
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#else
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# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
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#endif
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/* If the object is not yet relocated we cannot initialize the
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static TLS region. Delay it. */
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if (map->l_real->l_relocated)
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{
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#ifdef SHARED
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if (__builtin_expect (THREAD_DTV()[0].counter != GL(dl_tls_generation),
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0))
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/* Update the slot information data for at least the generation of
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the DSO we are allocating data for. */
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(void) _dl_update_slotinfo (map->l_tls_modid);
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#endif
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dl_init_static_tls (map);
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}
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else
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map->l_need_tls_init = 1;
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return 0;
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}
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/* This function intentionally does not return any value but signals error
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directly, as static TLS should be rare and code handling it should
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not be inlined as much as possible. */
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void
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__attribute_noinline__
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_dl_allocate_static_tls (struct link_map *map)
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{
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if (map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET
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|| _dl_try_allocate_static_tls (map, false))
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{
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_dl_signal_error (0, map->l_name, NULL, N_("\
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cannot allocate memory in static TLS block"));
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}
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}
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#if !THREAD_GSCOPE_IN_TCB
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/* Initialize static TLS area and DTV for current (only) thread.
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libpthread implementations should provide their own hook
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to handle all threads. */
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void
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_dl_nothread_init_static_tls (struct link_map *map)
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{
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#if TLS_TCB_AT_TP
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void *dest = (char *) THREAD_SELF - map->l_tls_offset;
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#elif TLS_DTV_AT_TP
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void *dest = (char *) THREAD_SELF + map->l_tls_offset + TLS_PRE_TCB_SIZE;
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#else
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# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
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#endif
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/* Initialize the memory. */
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memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
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'\0', map->l_tls_blocksize - map->l_tls_initimage_size);
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}
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#endif /* !THREAD_GSCOPE_IN_TCB */
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/* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */
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#define RESOLVE_MAP(l, scope, ref, version, r_type) \
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((ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL \
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&& __glibc_likely (!dl_symbol_visibility_binds_local_p (*ref))) \
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? ((__glibc_unlikely ((*ref) == l->l_lookup_cache.sym) \
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&& elf_machine_type_class (r_type) == l->l_lookup_cache.type_class) \
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? (bump_num_cache_relocations (), \
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(*ref) = l->l_lookup_cache.ret, \
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l->l_lookup_cache.value) \
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: ({ lookup_t _lr; \
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int _tc = elf_machine_type_class (r_type); \
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l->l_lookup_cache.type_class = _tc; \
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l->l_lookup_cache.sym = (*ref); \
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const struct r_found_version *v = NULL; \
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if ((version) != NULL && (version)->hash != 0) \
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v = (version); \
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_lr = _dl_lookup_symbol_x ((const char *) D_PTR (l, l_info[DT_STRTAB]) + (*ref)->st_name, \
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l, (ref), scope, v, _tc, \
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DL_LOOKUP_ADD_DEPENDENCY \
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| DL_LOOKUP_FOR_RELOCATE, NULL); \
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l->l_lookup_cache.ret = (*ref); \
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l->l_lookup_cache.value = _lr; })) \
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: l)
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#include "dynamic-link.h"
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void
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_dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
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int reloc_mode, int consider_profiling)
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{
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struct textrels
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{
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caddr_t start;
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size_t len;
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int prot;
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struct textrels *next;
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} *textrels = NULL;
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/* Initialize it to make the compiler happy. */
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const char *errstring = NULL;
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int lazy = reloc_mode & RTLD_LAZY;
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int skip_ifunc = reloc_mode & __RTLD_NOIFUNC;
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#ifdef SHARED
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/* If we are auditing, install the same handlers we need for profiling. */
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if ((reloc_mode & __RTLD_AUDIT) == 0)
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consider_profiling |= GLRO(dl_audit) != NULL;
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#elif defined PROF
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/* Never use dynamic linker profiling for gprof profiling code. */
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# define consider_profiling 0
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#endif
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if (l->l_relocated)
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return;
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/* If DT_BIND_NOW is set relocate all references in this object. We
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do not do this if we are profiling, of course. */
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// XXX Correct for auditing?
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if (!consider_profiling
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&& __builtin_expect (l->l_info[DT_BIND_NOW] != NULL, 0))
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lazy = 0;
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if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_RELOC))
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_dl_debug_printf ("\nrelocation processing: %s%s\n",
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DSO_FILENAME (l->l_name), lazy ? " (lazy)" : "");
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/* DT_TEXTREL is now in level 2 and might phase out at some time.
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But we rewrite the DT_FLAGS entry to a DT_TEXTREL entry to make
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testing easier and therefore it will be available at all time. */
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if (__glibc_unlikely (l->l_info[DT_TEXTREL] != NULL))
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{
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/* Bletch. We must make read-only segments writable
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long enough to relocate them. */
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const ElfW(Phdr) *ph;
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for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph)
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if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0)
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{
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struct textrels *newp;
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newp = (struct textrels *) alloca (sizeof (*newp));
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newp->len = ALIGN_UP (ph->p_vaddr + ph->p_memsz, GLRO(dl_pagesize))
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- ALIGN_DOWN (ph->p_vaddr, GLRO(dl_pagesize));
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newp->start = PTR_ALIGN_DOWN (ph->p_vaddr, GLRO(dl_pagesize))
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+ (caddr_t) l->l_addr;
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newp->prot = 0;
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if (ph->p_flags & PF_R)
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newp->prot |= PROT_READ;
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if (ph->p_flags & PF_W)
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newp->prot |= PROT_WRITE;
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if (ph->p_flags & PF_X)
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newp->prot |= PROT_EXEC;
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if (__mprotect (newp->start, newp->len, newp->prot|PROT_WRITE) < 0)
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{
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errstring = N_("cannot make segment writable for relocation");
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call_error:
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_dl_signal_error (errno, l->l_name, NULL, errstring);
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}
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newp->next = textrels;
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textrels = newp;
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}
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}
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{
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/* Do the actual relocation of the object's GOT and other data. */
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ELF_DYNAMIC_RELOCATE (l, scope, lazy, consider_profiling, skip_ifunc);
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#ifndef PROF
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if (__glibc_unlikely (consider_profiling)
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&& l->l_info[DT_PLTRELSZ] != NULL)
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{
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/* Allocate the array which will contain the already found
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relocations. If the shared object lacks a PLT (for example
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if it only contains lead function) the l_info[DT_PLTRELSZ]
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will be NULL. */
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size_t sizeofrel = l->l_info[DT_PLTREL]->d_un.d_val == DT_RELA
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? sizeof (ElfW(Rela))
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: sizeof (ElfW(Rel));
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size_t relcount = l->l_info[DT_PLTRELSZ]->d_un.d_val / sizeofrel;
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l->l_reloc_result = calloc (sizeof (l->l_reloc_result[0]), relcount);
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if (l->l_reloc_result == NULL)
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{
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errstring = N_("\
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%s: out of memory to store relocation results for %s\n");
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_dl_fatal_printf (errstring, RTLD_PROGNAME, l->l_name);
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}
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}
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#endif
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}
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/* Mark the object so we know this work has been done. */
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l->l_relocated = 1;
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/* Undo the segment protection changes. */
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while (__builtin_expect (textrels != NULL, 0))
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{
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if (__mprotect (textrels->start, textrels->len, textrels->prot) < 0)
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{
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errstring = N_("cannot restore segment prot after reloc");
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goto call_error;
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}
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#ifdef CLEAR_CACHE
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CLEAR_CACHE (textrels->start, textrels->start + textrels->len);
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#endif
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textrels = textrels->next;
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}
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/* In case we can protect the data now that the relocations are
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done, do it. */
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if (l->l_relro_size != 0)
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_dl_protect_relro (l);
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}
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void
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_dl_protect_relro (struct link_map *l)
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{
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ElfW(Addr) start = ALIGN_DOWN((l->l_addr
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+ l->l_relro_addr),
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GLRO(dl_pagesize));
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ElfW(Addr) end = ALIGN_DOWN((l->l_addr
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+ l->l_relro_addr
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+ l->l_relro_size),
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GLRO(dl_pagesize));
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if (start != end
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&& __mprotect ((void *) start, end - start, PROT_READ) < 0)
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{
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static const char errstring[] = N_("\
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cannot apply additional memory protection after relocation");
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_dl_signal_error (errno, l->l_name, NULL, errstring);
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}
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}
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void
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__attribute_noinline__
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_dl_reloc_bad_type (struct link_map *map, unsigned int type, int plt)
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{
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#define DIGIT(b) _itoa_lower_digits[(b) & 0xf];
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/* XXX We cannot translate these messages. */
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static const char msg[2][32
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#if __ELF_NATIVE_CLASS == 64
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+ 6
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#endif
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] = { "unexpected reloc type 0x",
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"unexpected PLT reloc type 0x" };
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char msgbuf[sizeof (msg[0])];
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char *cp;
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cp = __stpcpy (msgbuf, msg[plt]);
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#if __ELF_NATIVE_CLASS == 64
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if (__builtin_expect(type > 0xff, 0))
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{
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*cp++ = DIGIT (type >> 28);
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*cp++ = DIGIT (type >> 24);
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*cp++ = DIGIT (type >> 20);
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*cp++ = DIGIT (type >> 16);
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*cp++ = DIGIT (type >> 12);
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*cp++ = DIGIT (type >> 8);
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}
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#endif
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*cp++ = DIGIT (type >> 4);
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*cp++ = DIGIT (type);
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*cp = '\0';
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_dl_signal_error (0, map->l_name, NULL, msgbuf);
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}
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