diff options
Diffstat (limited to 'elf/setup-vdso.h')
| -rw-r--r-- | elf/setup-vdso.h | 119 |
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 +} |