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authorH.J. Lu <hjl.tools@gmail.com>2012-10-05 10:20:39 -0700
committerH.J. Lu <hjl.tools@gmail.com>2012-10-05 10:20:39 -0700
commit9cee55856438b714fa1efa45d8b7c1857467f4ca (patch)
tree450926ee00a192c70e6591d5fa4ebeded76d02f1 /elf/setup-vdso.h
parent28234b077ec6667b5dd0a6b60c6d8dbd9e28f6e1 (diff)
Set up the data structures for vDSO in libc.a
Diffstat (limited to 'elf/setup-vdso.h')
-rw-r--r--elf/setup-vdso.h119
1 files changed, 119 insertions, 0 deletions
diff --git a/elf/setup-vdso.h b/elf/setup-vdso.h
new file mode 100644
index 0000000000..1b969a0718
--- /dev/null
+++ b/elf/setup-vdso.h
@@ -0,0 +1,119 @@
+/* Set up the data structures for the system-supplied DSO.
+ Copyright (C) 2012 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
+ <http://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)))
+{
+#if defined NEED_DL_SYSINFO || defined 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 (__builtin_expect (l != NULL, 1))
+ {
+ 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);
+ 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);
+
+# ifdef 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;
+# 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
+}