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/* Set up the data structures for the system-supplied DSO.
Copyright (C) 2012-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
static inline void __attribute__ ((always_inline))
setup_vdso (struct link_map *main_map __attribute__ ((unused)),
struct link_map ***first_preload __attribute__ ((unused)))
{
#ifdef NEED_DL_SYSINFO_DSO
if (GLRO(dl_sysinfo_dso) == NULL)
return;
/* Do an abridged version of the work _dl_map_object_from_fd would do
to map in the object. It's already mapped and prelinked (and
better be, since it's read-only and so we couldn't relocate it).
We just want our data structures to describe it as if we had just
mapped and relocated it normally. */
struct link_map *l = _dl_new_object ((char *) "", "", lt_library, NULL,
0, LM_ID_BASE);
if (__glibc_likely (l != NULL))
{
static ElfW(Dyn) dyn_temp[DL_RO_DYN_TEMP_CNT] attribute_relro;
l->l_phdr = ((const void *) GLRO(dl_sysinfo_dso)
+ GLRO(dl_sysinfo_dso)->e_phoff);
l->l_phnum = GLRO(dl_sysinfo_dso)->e_phnum;
for (uint_fast16_t i = 0; i < l->l_phnum; ++i)
{
const ElfW(Phdr) *const ph = &l->l_phdr[i];
if (ph->p_type == PT_DYNAMIC)
{
l->l_ld = (void *) ph->p_vaddr;
l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn));
}
else if (ph->p_type == PT_LOAD)
{
if (! l->l_addr)
l->l_addr = ph->p_vaddr;
if (ph->p_vaddr + ph->p_memsz >= l->l_map_end)
l->l_map_end = ph->p_vaddr + ph->p_memsz;
if ((ph->p_flags & PF_X)
&& ph->p_vaddr + ph->p_memsz >= l->l_text_end)
l->l_text_end = ph->p_vaddr + ph->p_memsz;
}
else
/* There must be no TLS segment. */
assert (ph->p_type != PT_TLS);
}
l->l_map_start = (ElfW(Addr)) GLRO(dl_sysinfo_dso);
l->l_addr = l->l_map_start - l->l_addr;
l->l_map_end += l->l_addr;
l->l_text_end += l->l_addr;
l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr);
elf_get_dynamic_info (l, dyn_temp);
_dl_setup_hash (l);
l->l_relocated = 1;
/* The vDSO is always used. */
l->l_used = 1;
/* Initialize l_local_scope to contain just this map. This allows
the use of dl_lookup_symbol_x to resolve symbols within the vdso.
So we create a single entry list pointing to l_real as its only
element */
l->l_local_scope[0]->r_nlist = 1;
l->l_local_scope[0]->r_list = &l->l_real;
/* Now that we have the info handy, use the DSO image's soname
so this object can be looked up by name. Note that we do not
set l_name here. That field gives the file name of the DSO,
and this DSO is not associated with any file. */
if (l->l_info[DT_SONAME] != NULL)
{
/* Work around a kernel problem. The kernel cannot handle
addresses in the vsyscall DSO pages in writev() calls. */
const char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB])
+ l->l_info[DT_SONAME]->d_un.d_val);
size_t len = strlen (dsoname) + 1;
char *copy = malloc (len);
if (copy == NULL)
_dl_fatal_printf ("out of memory\n");
l->l_libname->name = l->l_name = memcpy (copy, dsoname, len);
}
/* Add the vDSO to the object list. */
_dl_add_to_namespace_list (l, LM_ID_BASE);
# if IS_IN (rtld)
/* Rearrange the list so this DSO appears after rtld_map. */
assert (l->l_next == NULL);
assert (l->l_prev == main_map);
GL(dl_rtld_map).l_next = l;
l->l_prev = &GL(dl_rtld_map);
*first_preload = &l->l_next;
# else
GL(dl_nns) = 1;
# endif
/* We have a prelinked DSO preloaded by the system. */
GLRO(dl_sysinfo_map) = l;
# ifdef NEED_DL_SYSINFO
if (GLRO(dl_sysinfo) == DL_SYSINFO_DEFAULT)
GLRO(dl_sysinfo) = GLRO(dl_sysinfo_dso)->e_entry + l->l_addr;
# endif
}
#endif
}
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