Prepare for radical source tree reorganization.zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 268 insertions, 0 deletions

diff --git a/REORG.TODO/sysdeps/i386/tlsdesc.c b/REORG.TODO/sysdeps/i386/tlsdesc.c
new file mode 100644
index 0000000000..90de2bb05e
--- /dev/null
+++ b/REORG.TODO/sysdeps/i386/tlsdesc.c
@@ -0,0 +1,268 @@
+/* Manage TLS descriptors.  i386 version.
+   Copyright (C) 2005-2017 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 <dl-unmap-segments.h>
+#include <tlsdeschtab.h>
+
+/* The following 4 functions take an entry_check_offset argument.
+   It's computed by the caller as an offset between its entry point
+   and the call site, such that by adding the built-in return address
+   that is implicitly passed to the function with this offset, we can
+   easily obtain the caller's entry point to compare with the entry
+   point given in the TLS descriptor.  If it's changed, we want to
+   return immediately.  */
+
+/* This function is used to lazily resolve TLS_DESC REL relocations
+   that reference the *ABS* segment in their own link maps.  The
+   argument is the addend originally stored there.  */
+
+void
+__attribute__ ((regparm (3))) attribute_hidden
+_dl_tlsdesc_resolve_abs_plus_addend_fixup (struct tlsdesc volatile *td,
+					   struct link_map *l,
+					   ptrdiff_t entry_check_offset)
+{
+  ptrdiff_t addend = (ptrdiff_t) td->arg;
+
+  if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
+					  - entry_check_offset))
+    return;
+
+#ifndef SHARED
+  CHECK_STATIC_TLS (l, l);
+#else
+  if (!TRY_STATIC_TLS (l, l))
+    {
+      td->arg = _dl_make_tlsdesc_dynamic (l, addend);
+      td->entry = _dl_tlsdesc_dynamic;
+    }
+  else
+#endif
+    {
+      td->arg = (void*) (addend - l->l_tls_offset);
+      td->entry = _dl_tlsdesc_return;
+    }
+
+  _dl_tlsdesc_wake_up_held_fixups ();
+}
+
+/* This function is used to lazily resolve TLS_DESC REL relocations
+   that originally had zero addends.  The argument location, that
+   originally held the addend, is used to hold a pointer to the
+   relocation, but it has to be restored before we call the function
+   that applies relocations.  */
+
+void
+__attribute__ ((regparm (3))) attribute_hidden
+_dl_tlsdesc_resolve_rel_fixup (struct tlsdesc volatile *td,
+			       struct link_map *l,
+			       ptrdiff_t entry_check_offset)
+{
+  const ElfW(Rel) *reloc = td->arg;
+
+  if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
+					  - entry_check_offset))
+    return;
+
+  /* The code below was borrowed from _dl_fixup(),
+     except for checking for STB_LOCAL.  */
+  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 = 0;
+      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);
+	  td->entry = _dl_tlsdesc_dynamic;
+	}
+      else
+#  endif
+	{
+	  td->arg = (void*)(sym->st_value - result->l_tls_offset);
+	  td->entry = _dl_tlsdesc_return;
+	}
+    }
+
+  _dl_tlsdesc_wake_up_held_fixups ();
+}
+
+/* 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__ ((regparm (3))) attribute_hidden
+_dl_tlsdesc_resolve_rela_fixup (struct tlsdesc volatile *td,
+				struct link_map *l,
+				ptrdiff_t entry_check_offset)
+{
+  const ElfW(Rela) *reloc = td->arg;
+
+  if (_dl_tlsdesc_resolve_early_return_p (td, __builtin_return_address (0)
+					  - entry_check_offset))
+    return;
+
+  /* The code below was borrowed from _dl_fixup(),
+     except for checking for STB_LOCAL.  */
+  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__ ((regparm (3))) attribute_hidden
+_dl_tlsdesc_resolve_hold_fixup (struct tlsdesc volatile *td,
+				struct link_map *l __attribute__((__unused__)),
+				ptrdiff_t entry_check_offset)
+{
+  /* Maybe we're lucky and can return early.  */
+  if (__builtin_return_address (0) - entry_check_offset != 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)
+{
+  _dl_unmap_segments (map);
+
+#ifdef SHARED
+  if (map->l_mach.tlsdesc_table)
+    htab_delete (map->l_mach.tlsdesc_table);
+#endif
+}