elf: Fix dynamic-link.h usage on rtld.c

The 4af6982e4c fix does not fully handle RTLD_BOOTSTRAP usage on
rtld.c due two issues:

  1. RTLD_BOOTSTRAP is also used on dl-machine.h on various
     architectures and it changes the semantics of various machine
     relocation functions.

  2. The elf_get_dynamic_info() change was done sideways, previously
     to 490e6c62aa get-dynamic-info.h was included by the first
     dynamic-link.h include *without* RTLD_BOOTSTRAP being defined.
     It means that the code within elf_get_dynamic_info() that uses
     RTLD_BOOTSTRAP is in fact unused.

To fix 1. this patch now includes dynamic-link.h only once with
RTLD_BOOTSTRAP defined.  The ELF_DYNAMIC_RELOCATE call will now have
the relocation fnctions with the expected semantics for the loader.

And to fix 2. part of 4af6982e4c is reverted (the check argument
elf_get_dynamic_info() is not required) and the RTLD_BOOTSTRAP
pieces are removed.

To reorganize the includes the static TLS definition is moved to
its own header to avoid a circular dependency (it is defined on
dynamic-link.h and dl-machine.h requires it at same time other
dynamic-link.h definition requires dl-machine.h defitions).

Also ELF_MACHINE_NO_REL, ELF_MACHINE_NO_RELA, and ELF_MACHINE_PLT_REL
are moved to its own header.  Only ancient ABIs need special values
(arm, i386, and mips), so a generic one is used as default.

The powerpc Elf64_FuncDesc is also moved to its own header, since
csu code required its definition (which would require either include
elf/ folder or add a full path with elf/).

Checked on x86_64, i686, aarch64, armhf, powerpc64, powerpc32,
and powerpc64le.

Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>

1 files changed, 51 insertions, 0 deletions

diff --git a/elf/dl-static-tls.h b/elf/dl-static-tls.h
new file mode 100644
index 0000000000..730924fc01
--- /dev/null
+++ b/elf/dl-static-tls.h
@@ -0,0 +1,51 @@
+/* Inline functions for dynamic linking.
+   Copyright (C) 1995-2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _DL_STATIC_TLS_H
+#define _DL_STATIC_TLS_H
+
+/* This macro is used as a callback from elf_machine_rel{a,} when a
+   static TLS reloc is about to be performed.  Since (in dl-load.c) we
+   permit dynamic loading of objects that might use such relocs, we
+   have to check whether each use is actually doable.  If the object
+   whose TLS segment the reference resolves to was allocated space in
+   the static TLS block at startup, then it's ok.  Otherwise, we make
+   an attempt to allocate it in surplus space on the fly.  If that
+   can't be done, we fall back to the error that DF_STATIC_TLS is
+   intended to produce.  */
+#define HAVE_STATIC_TLS(map, sym_map)					\
+    (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET		\
+		       && ((sym_map)->l_tls_offset			\
+			   != FORCED_DYNAMIC_TLS_OFFSET), 1))
+
+#define CHECK_STATIC_TLS(map, sym_map)					\
+    do {								\
+      if (!HAVE_STATIC_TLS (map, sym_map))				\
+	_dl_allocate_static_tls (sym_map);				\
+    } while (0)
+
+#define TRY_STATIC_TLS(map, sym_map)					\
+    (__builtin_expect ((sym_map)->l_tls_offset				\
+		       != FORCED_DYNAMIC_TLS_OFFSET, 1)			\
+     && (__builtin_expect ((sym_map)->l_tls_offset != NO_TLS_OFFSET, 1)	\
+	 || _dl_try_allocate_static_tls (sym_map, true) == 0))
+
+int _dl_try_allocate_static_tls (struct link_map *map, bool optional)
+  attribute_hidden;
+
+#endif