diff options
Diffstat (limited to 'sysdeps/arm/tlsdesc.c')
| -rw-r--r-- | sysdeps/arm/tlsdesc.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/sysdeps/arm/tlsdesc.c b/sysdeps/arm/tlsdesc.c new file mode 100644 index 0000000000..fc754d6c42 --- /dev/null +++ b/sysdeps/arm/tlsdesc.c @@ -0,0 +1,160 @@ +/* Manage TLS descriptors. ARM version. + Copyright (C) 2005-2014 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/>. */ + +#include <link.h> +#include <ldsodefs.h> +#include <elf/dynamic-link.h> +#include <tls.h> +#include <dl-tlsdesc.h> +#include <tlsdeschtab.h> + +/* This function is used to lazily resolve TLS_DESC REL relocations + Besides the TLS descriptor itself, we get the module's got address + as the second parameter. */ + +void +attribute_hidden +_dl_tlsdesc_lazy_resolver_fixup (struct tlsdesc volatile *td, + Elf32_Addr *got) +{ + struct link_map *l = (struct link_map *)got[1]; + lookup_t result; + unsigned long value; + + if (_dl_tlsdesc_resolve_early_return_p + (td, (void*)(D_PTR (l, l_info[ADDRIDX (DT_TLSDESC_PLT)]) + l->l_addr))) + return; + + if (td->argument.value & 0x80000000) + { + /* A global symbol, this is the symbol index. */ + /* The code below was borrowed from _dl_fixup(). */ + const Elf_Symndx symndx = td->argument.value ^ 0x80000000; + 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[symndx]; + + /* 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[symndx] & 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); + if (sym) + value = sym->st_value; + else + { + td->entry = _dl_tlsdesc_undefweak; + goto done; + } + } + else + { + /* We already found the symbol. The module (and therefore its load + address) is also known. */ + result = l; + value = sym->st_value; + } + } + else + { + /* A local symbol, this is the offset within our tls section. + */ + value = td->argument.value; + result = l; + } + +#ifndef SHARED + CHECK_STATIC_TLS (l, result); +#else + if (!TRY_STATIC_TLS (l, result)) + { + td->argument.pointer = _dl_make_tlsdesc_dynamic (result, value); + td->entry = _dl_tlsdesc_dynamic; + } + else +#endif + { + td->argument.value = value + result->l_tls_offset; + td->entry = _dl_tlsdesc_return; + } + + done: + _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 +} |