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Diffstat (limited to 'sysdeps/x86_64/tlsdesc.c')
| -rw-r--r-- | sysdeps/x86_64/tlsdesc.c | 151 |
1 files changed, 151 insertions, 0 deletions
diff --git a/sysdeps/x86_64/tlsdesc.c b/sysdeps/x86_64/tlsdesc.c new file mode 100644 index 0000000000..0cc32aab69 --- /dev/null +++ b/sysdeps/x86_64/tlsdesc.c @@ -0,0 +1,151 @@ +/* Manage TLS descriptors. x86_64 version. + Copyright (C) 2005, 2008 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <link.h> +#include <ldsodefs.h> +#include <elf/dynamic-link.h> +#include <tls.h> +#include <dl-tlsdesc.h> +#include <tlsdeschtab.h> + +/* The following 2 functions take a caller argument, that contains the + address expected to be in the TLS descriptor. If it's changed, we + want to return immediately. */ + +/* This function is used to lazily resolve TLS_DESC RELA relocations. + The argument location is used to hold a pointer to the relocation. */ + +void +attribute_hidden +_dl_tlsdesc_resolve_rela_fixup (struct tlsdesc volatile *td, + struct link_map *l) +{ + const ElfW(Rela) *reloc = td->arg; + + if (_dl_tlsdesc_resolve_early_return_p + (td, (void*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_PLT)]) + l->l_addr))) + return; + + /* The code below was borrowed from _dl_fixup(). */ + const ElfW(Sym) *const symtab + = (const void *) D_PTR (l, l_info[DT_SYMTAB]); + const char *strtab = (const void *) D_PTR (l, l_info[DT_STRTAB]); + const ElfW(Sym) *sym = &symtab[ELFW(R_SYM) (reloc->r_info)]; + lookup_t result; + + /* Look up the target symbol. If the normal lookup rules are not + used don't look in the global scope. */ + if (ELFW(ST_BIND) (sym->st_info) != STB_LOCAL + && __builtin_expect (ELFW(ST_VISIBILITY) (sym->st_other), 0) == 0) + { + const struct r_found_version *version = NULL; + + if (l->l_info[VERSYMIDX (DT_VERSYM)] != NULL) + { + const ElfW(Half) *vernum = + (const void *) D_PTR (l, l_info[VERSYMIDX (DT_VERSYM)]); + ElfW(Half) ndx = vernum[ELFW(R_SYM) (reloc->r_info)] & 0x7fff; + version = &l->l_versions[ndx]; + if (version->hash == 0) + version = NULL; + } + + result = _dl_lookup_symbol_x (strtab + sym->st_name, l, &sym, + l->l_scope, version, ELF_RTYPE_CLASS_PLT, + DL_LOOKUP_ADD_DEPENDENCY, NULL); + } + else + { + /* We already found the symbol. The module (and therefore its load + address) is also known. */ + result = l; + } + + if (! sym) + { + td->arg = (void*)reloc->r_addend; + td->entry = _dl_tlsdesc_undefweak; + } + else + { +# ifndef SHARED + CHECK_STATIC_TLS (l, result); +# else + if (!TRY_STATIC_TLS (l, result)) + { + td->arg = _dl_make_tlsdesc_dynamic (result, sym->st_value + + reloc->r_addend); + td->entry = _dl_tlsdesc_dynamic; + } + else +# endif + { + td->arg = (void*)(sym->st_value - result->l_tls_offset + + reloc->r_addend); + td->entry = _dl_tlsdesc_return; + } + } + + _dl_tlsdesc_wake_up_held_fixups (); +} + +/* This function is used to avoid busy waiting for other threads to + complete the lazy relocation. Once another thread wins the race to + relocate a TLS descriptor, it sets the descriptor up such that this + function is called to wait until the resolver releases the + lock. */ + +void +attribute_hidden +_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td, + void *caller) +{ + /* Maybe we're lucky and can return early. */ + if (caller != td->entry) + return; + + /* Locking here will stop execution until the running resolver runs + _dl_tlsdesc_wake_up_held_fixups(), releasing the lock. + + FIXME: We'd be better off waiting on a condition variable, such + that we didn't have to hold the lock throughout the relocation + processing. */ + __rtld_lock_lock_recursive (GL(dl_load_lock)); + __rtld_lock_unlock_recursive (GL(dl_load_lock)); +} + +/* Unmap the dynamic object, but also release its TLS descriptor table + if there is one. */ + +void +internal_function +_dl_unmap (struct link_map *map) +{ + __munmap ((void *) (map)->l_map_start, + (map)->l_map_end - (map)->l_map_start); + +#if SHARED + /* _dl_unmap is only called for dlopen()ed libraries, for which + calling free() is safe, or before we've completed the initial + relocation, in which case calling free() is probably pointless, + but still safe. */ + if (map->l_mach.tlsdesc_table) + htab_delete (map->l_mach.tlsdesc_table); +#endif +} |