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95e7cf295e
Long ago static startup did not parse the auxiliary vector and therefore
could not get at any `AT_FPUCW' tag to check whether upon FPU context
allocation the kernel would use a FPU control word setting different to
that provided by the `__fpu_control' variable. Static startup therefore
always initialized the FPU control word, forcing immediate FPU context
allocation even for binaries that otherwise never used the FPU.
As from GIT commit f8f900ecb9
static
startup supports parsing the auxiliary vector, so now it can avoid
explicit initialization of the FPU control word, just as can dynamic
startup, in the usual case where the setting written to the FPU control
word would be the same as the kernel uses. This defers FPU context
allocation until the binary itself actually pokes at the FPU.
Note that the `AT_FPUCW' tag is usually absent from the auxiliary vector
in which case _FPU_DEFAULT is assumed to be the kernel default.
387 lines
10 KiB
C
387 lines
10 KiB
C
/* Support for dynamic linking code in static libc.
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Copyright (C) 1996-2013 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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<http://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 <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 <bits/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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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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ElfW(Addr) _dl_use_load_bias = -2;
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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-procinfo.c>
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/* We expect less than a second for relocation. */
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#ifdef HP_SMALL_TIMING_AVAIL
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# undef HP_TIMING_AVAIL
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# define HP_TIMING_AVAIL HP_SMALL_TIMING_AVAIL
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#endif
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/* Initial value of the CPU clock. */
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#ifndef HP_TIMING_NONAVAIL
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hp_timing_t _dl_cpuclock_offset;
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#endif
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void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
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size_t _dl_pagesize = EXEC_PAGESIZE;
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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 __attribute__ ((nocommon));
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uint64_t _dl_hwcap2 __attribute__ ((nocommon));
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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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/* 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 __attribute__ ((nocommon));
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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 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 **) internal_function
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= _dl_make_stack_executable;
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/* Function in libpthread to wait for termination of lookups. */
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void (*_dl_wait_lookup_done) (void);
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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. */
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uintptr_t _dl_sysinfo = DL_SYSINFO_DEFAULT;
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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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/* 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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#ifdef HAVE_AUX_VECTOR
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int _dl_clktck;
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void
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internal_function
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_dl_aux_init (ElfW(auxv_t) *av)
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{
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int seen = 0;
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uid_t uid = 0;
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gid_t gid = 0;
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_dl_auxv = av;
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for (; av->a_type != AT_NULL; ++av)
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switch (av->a_type)
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{
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case AT_PAGESZ:
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if (av->a_un.a_val != 0)
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GLRO(dl_pagesize) = av->a_un.a_val;
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break;
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case AT_CLKTCK:
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GLRO(dl_clktck) = av->a_un.a_val;
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break;
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case AT_PHDR:
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GL(dl_phdr) = (const void *) av->a_un.a_val;
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break;
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case AT_PHNUM:
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GL(dl_phnum) = av->a_un.a_val;
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break;
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case AT_HWCAP:
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GLRO(dl_hwcap) = (unsigned long int) av->a_un.a_val;
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break;
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case AT_HWCAP2:
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GLRO(dl_hwcap2) = (unsigned long int) av->a_un.a_val;
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break;
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case AT_FPUCW:
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GLRO(dl_fpu_control) = av->a_un.a_val;
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break;
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#ifdef NEED_DL_SYSINFO
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case AT_SYSINFO:
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GL(dl_sysinfo) = av->a_un.a_val;
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break;
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#endif
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#ifdef NEED_DL_SYSINFO_DSO
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case AT_SYSINFO_EHDR:
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GL(dl_sysinfo_dso) = (void *) av->a_un.a_val;
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break;
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#endif
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case AT_UID:
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uid ^= av->a_un.a_val;
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seen |= 1;
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break;
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case AT_EUID:
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uid ^= av->a_un.a_val;
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seen |= 2;
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break;
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case AT_GID:
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gid ^= av->a_un.a_val;
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seen |= 4;
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break;
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case AT_EGID:
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gid ^= av->a_un.a_val;
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seen |= 8;
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break;
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case AT_SECURE:
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seen = -1;
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__libc_enable_secure = av->a_un.a_val;
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__libc_enable_secure_decided = 1;
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break;
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case AT_RANDOM:
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_dl_random = (void *) av->a_un.a_val;
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break;
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# ifdef DL_PLATFORM_AUXV
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DL_PLATFORM_AUXV
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# endif
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}
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if (seen == 0xf)
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{
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__libc_enable_secure = uid != 0 || gid != 0;
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__libc_enable_secure_decided = 1;
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}
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}
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#endif
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void
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internal_function
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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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if (HP_TIMING_AVAIL)
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HP_TIMING_NOW (_dl_cpuclock_offset);
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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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/* 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"));
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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 (__access ("/etc/suid-debug", F_OK) != 0)
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__unsetenv ("MALLOC_CHECK_");
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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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/* Scan for a program header telling us the stack is nonexecutable. */
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if (_dl_phdr != NULL)
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for (uint_fast16_t i = 0; i < _dl_phnum; ++i)
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if (_dl_phdr[i].p_type == PT_GNU_STACK)
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{
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_dl_stack_flags = _dl_phdr[i].p_flags;
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break;
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}
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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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