mirror of
git://sourceware.org/git/glibc.git
synced 2024-12-09 04:11:27 +08:00
73fc4e28b9
And optimize it slightly.
This is commit 8c8510ab27
revised.
In _dl_aux_init in elf/dl-support.c, use an explicit loop
and -fno-tree-loop-distribute-patterns to avoid memset.
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
382 lines
11 KiB
C
382 lines
11 KiB
C
/* Support for dynamic linking code in static libc.
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Copyright (C) 1996-2022 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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/* This file defines some things that for the dynamic linker are defined in
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rtld.c and dl-sysdep.c in ways appropriate to bootstrap dynamic linking. */
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#include <string.h>
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/* Mark symbols hidden in static PIE for early self relocation to work.
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Note: string.h may have ifuncs which cannot be hidden on i686. */
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#if BUILD_PIE_DEFAULT
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# pragma GCC visibility push(hidden)
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#endif
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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 <sys/param.h>
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#include <stdint.h>
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#include <ldsodefs.h>
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#include <dl-machine.h>
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#include <libc-lock.h>
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#include <dl-cache.h>
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#include <dl-librecon.h>
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#include <dl-procinfo.h>
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#include <unsecvars.h>
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#include <hp-timing.h>
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#include <stackinfo.h>
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#include <dl-vdso.h>
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#include <dl-vdso-setup.h>
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#include <dl-auxv.h>
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#include <dl-find_object.h>
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#include <array_length.h>
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extern char *__progname;
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char **_dl_argv = &__progname; /* This is checked for some error messages. */
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/* Name of the architecture. */
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const char *_dl_platform;
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size_t _dl_platformlen;
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int _dl_debug_mask;
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int _dl_lazy;
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int _dl_dynamic_weak;
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/* If nonzero print warnings about problematic situations. */
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int _dl_verbose;
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/* We never do profiling. */
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const char *_dl_profile;
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const char *_dl_profile_output;
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/* Names of shared object for which the RUNPATHs and RPATHs should be
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ignored. */
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const char *_dl_inhibit_rpath;
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/* The map for the object we will profile. */
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struct link_map *_dl_profile_map;
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/* This is the address of the last stack address ever used. */
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void *__libc_stack_end;
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/* Path where the binary is found. */
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const char *_dl_origin_path;
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/* Nonzero if runtime lookup should not update the .got/.plt. */
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int _dl_bind_not;
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/* A dummy link map for the executable, used by dlopen to access the global
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scope. We don't export any symbols ourselves, so this can be minimal. */
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static struct link_map _dl_main_map =
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{
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.l_name = (char *) "",
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.l_real = &_dl_main_map,
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.l_ns = LM_ID_BASE,
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.l_libname = &(struct libname_list) { .name = "", .dont_free = 1 },
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.l_searchlist =
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{
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.r_list = &(struct link_map *) { &_dl_main_map },
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.r_nlist = 1,
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},
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.l_symbolic_searchlist = { .r_list = &(struct link_map *) { NULL } },
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.l_type = lt_executable,
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.l_scope_mem = { &_dl_main_map.l_searchlist },
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.l_scope_max = (sizeof (_dl_main_map.l_scope_mem)
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/ sizeof (_dl_main_map.l_scope_mem[0])),
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.l_scope = _dl_main_map.l_scope_mem,
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.l_local_scope = { &_dl_main_map.l_searchlist },
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.l_used = 1,
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.l_tls_offset = NO_TLS_OFFSET,
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.l_serial = 1,
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};
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/* Namespace information. */
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struct link_namespaces _dl_ns[DL_NNS] =
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{
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[LM_ID_BASE] =
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{
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._ns_loaded = &_dl_main_map,
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._ns_nloaded = 1,
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._ns_main_searchlist = &_dl_main_map.l_searchlist,
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}
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};
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size_t _dl_nns = 1;
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/* Incremented whenever something may have been added to dl_loaded. */
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unsigned long long _dl_load_adds = 1;
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/* Fake scope of the main application. */
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struct r_scope_elem _dl_initial_searchlist =
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{
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.r_list = &(struct link_map *) { &_dl_main_map },
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.r_nlist = 1,
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};
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#ifndef HAVE_INLINED_SYSCALLS
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/* Nonzero during startup. */
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int _dl_starting_up = 1;
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#endif
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/* Random data provided by the kernel. */
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void *_dl_random;
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/* Get architecture specific initializer. */
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#include <dl-procruntime.c>
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#include <dl-procinfo.c>
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size_t _dl_pagesize = EXEC_PAGESIZE;
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size_t _dl_minsigstacksize = CONSTANT_MINSIGSTKSZ;
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int _dl_inhibit_cache;
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unsigned int _dl_osversion;
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/* All known directories in sorted order. */
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struct r_search_path_elem *_dl_all_dirs;
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/* All directories after startup. */
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struct r_search_path_elem *_dl_init_all_dirs;
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/* The object to be initialized first. */
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struct link_map *_dl_initfirst;
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/* Descriptor to write debug messages to. */
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int _dl_debug_fd = STDERR_FILENO;
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int _dl_correct_cache_id = _DL_CACHE_DEFAULT_ID;
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ElfW(auxv_t) *_dl_auxv;
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const ElfW(Phdr) *_dl_phdr;
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size_t _dl_phnum;
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uint64_t _dl_hwcap;
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uint64_t _dl_hwcap2;
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enum dso_sort_algorithm _dl_dso_sort_algo;
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/* The value of the FPU control word the kernel will preset in hardware. */
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fpu_control_t _dl_fpu_control = _FPU_DEFAULT;
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#if !HAVE_TUNABLES
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/* This is not initialized to HWCAP_IMPORTANT, matching the definition
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of _dl_important_hwcaps, below, where no hwcap strings are ever
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used. This mask is still used to mediate the lookups in the cache
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file. Since there is no way to set this nonzero (we don't grok the
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LD_HWCAP_MASK environment variable here), there is no real point in
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setting _dl_hwcap nonzero below, but we do anyway. */
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uint64_t _dl_hwcap_mask;
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#endif
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/* Prevailing state of the stack. Generally this includes PF_X, indicating it's
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* executable but this isn't true for all platforms. */
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ElfW(Word) _dl_stack_flags = DEFAULT_STACK_PERMS;
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#if PTHREAD_IN_LIBC
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list_t _dl_stack_used;
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list_t _dl_stack_user;
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list_t _dl_stack_cache;
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size_t _dl_stack_cache_actsize;
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uintptr_t _dl_in_flight_stack;
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int _dl_stack_cache_lock;
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#else
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/* If loading a shared object requires that we make the stack executable
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when it was not, we do it by calling this function.
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It returns an errno code or zero on success. */
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int (*_dl_make_stack_executable_hook) (void **) = _dl_make_stack_executable;
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void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
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#endif
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struct dl_scope_free_list *_dl_scope_free_list;
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#ifdef NEED_DL_SYSINFO
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/* Needed for improved syscall handling on at least x86/Linux. NB: Don't
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initialize it here to avoid RELATIVE relocation in static PIE. */
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uintptr_t _dl_sysinfo;
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#endif
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#ifdef NEED_DL_SYSINFO_DSO
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/* Address of the ELF headers in the vsyscall page. */
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const ElfW(Ehdr) *_dl_sysinfo_dso;
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struct link_map *_dl_sysinfo_map;
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# include "get-dynamic-info.h"
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#endif
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#include "setup-vdso.h"
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/* Define the vDSO function pointers. */
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#include <dl-vdso-setup.c>
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/* During the program run we must not modify the global data of
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loaded shared object simultanously in two threads. Therefore we
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protect `_dl_open' and `_dl_close' in dl-close.c.
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This must be a recursive lock since the initializer function of
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the loaded object might as well require a call to this function.
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At this time it is not anymore a problem to modify the tables. */
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__rtld_lock_define_initialized_recursive (, _dl_load_lock)
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/* This lock is used to keep __dl_iterate_phdr from inspecting the
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list of loaded objects while an object is added to or removed from
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that list. */
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__rtld_lock_define_initialized_recursive (, _dl_load_write_lock)
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/* This lock protects global and module specific TLS related data.
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E.g. it is held in dlopen and dlclose when GL(dl_tls_generation),
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GL(dl_tls_max_dtv_idx) or GL(dl_tls_dtv_slotinfo_list) are
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accessed and when TLS related relocations are processed for a
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module. It was introduced to keep pthread_create accessing TLS
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state that is being set up. */
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__rtld_lock_define_initialized_recursive (, _dl_load_tls_lock)
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#ifdef HAVE_AUX_VECTOR
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#include <dl-parse_auxv.h>
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int _dl_clktck;
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void
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_dl_aux_init (ElfW(auxv_t) *av)
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{
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#ifdef NEED_DL_SYSINFO
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/* NB: Avoid RELATIVE relocation in static PIE. */
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GL(dl_sysinfo) = DL_SYSINFO_DEFAULT;
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#endif
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_dl_auxv = av;
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dl_parse_auxv_t auxv_values;
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/* Use an explicit initialization loop here because memset may not
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be available yet. */
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for (int i = 0; i < array_length (auxv_values); ++i)
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auxv_values[i] = 0;
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_dl_parse_auxv (av, auxv_values);
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}
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#endif
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void
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_dl_non_dynamic_init (void)
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{
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_dl_main_map.l_origin = _dl_get_origin ();
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_dl_main_map.l_phdr = GL(dl_phdr);
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_dl_main_map.l_phnum = GL(dl_phnum);
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_dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
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/* Set up the data structures for the system-supplied DSO early,
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so they can influence _dl_init_paths. */
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setup_vdso (NULL, NULL);
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/* With vDSO setup we can initialize the function pointers. */
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setup_vdso_pointers ();
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/* Initialize the data structures for the search paths for shared
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objects. */
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_dl_init_paths (getenv ("LD_LIBRARY_PATH"), "LD_LIBRARY_PATH",
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/* No glibc-hwcaps selection support in statically
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linked binaries. */
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NULL, NULL);
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/* Remember the last search directory added at startup. */
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_dl_init_all_dirs = GL(dl_all_dirs);
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_dl_lazy = *(getenv ("LD_BIND_NOW") ?: "") == '\0';
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_dl_bind_not = *(getenv ("LD_BIND_NOT") ?: "") != '\0';
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_dl_dynamic_weak = *(getenv ("LD_DYNAMIC_WEAK") ?: "") == '\0';
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_dl_profile_output = getenv ("LD_PROFILE_OUTPUT");
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if (_dl_profile_output == NULL || _dl_profile_output[0] == '\0')
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_dl_profile_output
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= &"/var/tmp\0/var/profile"[__libc_enable_secure ? 9 : 0];
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if (__libc_enable_secure)
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{
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static const char unsecure_envvars[] =
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UNSECURE_ENVVARS
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#ifdef EXTRA_UNSECURE_ENVVARS
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EXTRA_UNSECURE_ENVVARS
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#endif
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;
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const char *cp = unsecure_envvars;
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while (cp < unsecure_envvars + sizeof (unsecure_envvars))
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{
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__unsetenv (cp);
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cp = (const char *) __rawmemchr (cp, '\0') + 1;
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}
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#if !HAVE_TUNABLES
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if (__access ("/etc/suid-debug", F_OK) != 0)
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__unsetenv ("MALLOC_CHECK_");
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#endif
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}
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#ifdef DL_PLATFORM_INIT
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DL_PLATFORM_INIT;
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#endif
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#ifdef DL_OSVERSION_INIT
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DL_OSVERSION_INIT;
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#endif
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/* Now determine the length of the platform string. */
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if (_dl_platform != NULL)
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_dl_platformlen = strlen (_dl_platform);
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if (_dl_phdr != NULL)
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for (const ElfW(Phdr) *ph = _dl_phdr; ph < &_dl_phdr[_dl_phnum]; ++ph)
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switch (ph->p_type)
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{
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/* Check if the stack is nonexecutable. */
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case PT_GNU_STACK:
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_dl_stack_flags = ph->p_flags;
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break;
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case PT_GNU_RELRO:
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_dl_main_map.l_relro_addr = ph->p_vaddr;
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_dl_main_map.l_relro_size = ph->p_memsz;
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break;
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}
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call_function_static_weak (_dl_find_object_init);
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/* Setup relro on the binary itself. */
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if (_dl_main_map.l_relro_size != 0)
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_dl_protect_relro (&_dl_main_map);
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}
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#ifdef DL_SYSINFO_IMPLEMENTATION
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DL_SYSINFO_IMPLEMENTATION
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#endif
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#if ENABLE_STATIC_PIE
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/* Since relocation to hidden _dl_main_map causes relocation overflow on
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aarch64, a function is used to get the address of _dl_main_map. */
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struct link_map *
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_dl_get_dl_main_map (void)
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{
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return &_dl_main_map;
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}
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#endif
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/* This is used by _dl_runtime_profile, not used on static code. */
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void
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DL_ARCH_FIXUP_ATTRIBUTE
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_dl_audit_pltexit (struct link_map *l, ElfW(Word) reloc_arg,
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const void *inregs, void *outregs)
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{
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}
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