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372 lines
12 KiB
C
372 lines
12 KiB
C
/* Relocate a shared object and resolve its references to other loaded objects.
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Copyright (C) 1995-2006, 2008-2010, 2011 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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#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 "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. If it fits,
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we set MAP->l_tls_offset and return.
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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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int
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internal_function
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_dl_try_allocate_static_tls (struct link_map *map)
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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 > GL(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 = GL(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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size_t offset = GL(dl_tls_static_used) + (freebytes - n * map->l_tls_align
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- map->l_tls_firstbyte_offset);
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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 = (((GL(dl_tls_static_used)
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- map->l_tls_firstbyte_offset
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+ map->l_tls_align - 1) & -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 > GL(dl_tls_static_size))
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goto fail;
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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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GL(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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void
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internal_function __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))
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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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/* 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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/* Fill in the DTV slot so that a later LD/GD access will find it. */
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dtv_t *dtv = THREAD_DTV ();
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assert (map->l_tls_modid <= dtv[-1].counter);
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dtv[map->l_tls_modid].pointer.val = dest;
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dtv[map->l_tls_modid].pointer.is_static = true;
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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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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 (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_RELOC, 0))
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_dl_debug_printf ("\nrelocation processing: %s%s\n",
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l->l_name[0] ? l->l_name : rtld_progname,
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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 (__builtin_expect (l->l_info[DT_TEXTREL] != NULL, 0))
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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 = (((ph->p_vaddr + ph->p_memsz + GLRO(dl_pagesize) - 1)
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& ~(GLRO(dl_pagesize) - 1))
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- (ph->p_vaddr & ~(GLRO(dl_pagesize) - 1)));
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newp->start = ((ph->p_vaddr & ~(GLRO(dl_pagesize) - 1))
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+ (caddr_t) l->l_addr);
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if (__mprotect (newp->start, newp->len, PROT_READ|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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#if (PF_R | PF_W | PF_X) == 7 && (PROT_READ | PROT_WRITE | PROT_EXEC) == 7
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newp->prot = (PF_TO_PROT
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>> ((ph->p_flags & (PF_R | PF_W | PF_X)) * 4)) & 0xf;
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#else
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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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#endif
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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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/* String table object symbols. */
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const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]);
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/* This macro is used as a callback from the ELF_DYNAMIC_RELOCATE code. */
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#define RESOLVE_MAP(ref, version, r_type) \
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(ELFW(ST_BIND) ((*ref)->st_info) != STB_LOCAL \
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? ((__builtin_expect ((*ref) == l->l_lookup_cache.sym, 0) \
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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 (strtab + (*ref)->st_name, l, (ref), \
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scope, v, _tc, \
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DL_LOOKUP_ADD_DEPENDENCY, 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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ELF_DYNAMIC_RELOCATE (l, lazy, consider_profiling, skip_ifunc);
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#ifndef PROF
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if (__builtin_expect (consider_profiling, 0))
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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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if (l->l_info[DT_PLTRELSZ] == NULL)
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{
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errstring = N_("%s: no PLTREL found in object %s\n");
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fatal:
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_dl_fatal_printf (errstring,
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rtld_progname ?: "<program name unknown>",
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l->l_name);
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}
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l->l_reloc_result = calloc (sizeof (l->l_reloc_result[0]),
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l->l_info[DT_PLTRELSZ]->d_un.d_val);
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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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goto fatal;
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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 internal_function
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_dl_protect_relro (struct link_map *l)
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{
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ElfW(Addr) start = ((l->l_addr + l->l_relro_addr)
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& ~(GLRO(dl_pagesize) - 1));
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ElfW(Addr) end = ((l->l_addr + l->l_relro_addr + l->l_relro_size)
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& ~(GLRO(dl_pagesize) - 1));
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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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internal_function __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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extern const char INTUSE(_itoa_lower_digits)[] attribute_hidden;
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#define DIGIT(b) INTUSE(_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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