ld.so boot cleanup support:

- put functions and data which are only used before calling the executable's
start function into their own page-aligned segments for unmapping
(only done on amd64, arm64, armv7, powerpc, and sparc64 so far)
- pass .init_array and .preinit_array functions an addition argument which
is a callback to get a structure which includes a function that frees
the boot text and data
- sometimes delay doing RELRO processing: for a shared-object marked
DF_1_INITFIRST do it after the object's .init_array, for the executable
do it after the .preinit_array
- improve test-ld.so to link against libpthread and trigger its initialization
late
libc changes to use this will come later
ok kettenis@

src/etc/rc

@@ -1,4 +1,4 @@
-#	$OpenBSD: rc,v 1.536 2019/04/01 11:39:46 tedu Exp $
+#	$OpenBSD: rc,v 1.537 2019/05/10 13:29:21 guenther Exp $
 
 # System startup script run by init on autoboot or after single-user.
 # Output and error are redirected to console by init, and the console is the
@@ -210,9 +210,11 @@ reorder_libs() {
 		cd $_tmpdir
 		ar x $_liba
 		if [[ $_lib == ld.so ]]; then
-			ld -g -x -e _dl_start \
+			args="-g -x -e _dl_start \
 			    --version-script=Symbols.map --shared -Bsymbolic \
-			    --no-undefined -o ld.so.test $(ls *.o | sort -R)
+			    --no-undefined"
+			[[ -f ld.script ]] && args="$args -T ld.script"
+			ld $args -o ld.so.test $(ls *.o | sort -R)
 			chmod u+x test-ld.so
 			[[ $(./test-ld.so ok) == './test-ld.so: ok!' ]]
 			$_install /usr/libexec/ld.so /usr/libexec/ld.so.save

src/include/tib.h

@@ -1,4 +1,4 @@
-/*	$OpenBSD: tib.h,v 1.6 2017/11/28 18:57:02 kettenis Exp $	*/
+/*	$OpenBSD: tib.h,v 1.7 2019/05/10 13:29:21 guenther Exp $	*/
 /*
  * Copyright (c) 2011,2014 Philip Guenther <guenther@openbsd.org>
  *
@@ -225,6 +225,28 @@ struct tib {
 
 
 __BEGIN_DECLS
+struct dl_info;
+struct dl_phdr_info;
+struct dl_cb_0 {
+	void	*(*dl_allocate_tib)(size_t);
+	void	 (*dl_free_tib)(void *, size_t);
+	void	 (*dl_clean_boot)(void);
+	void	*(*dlopen)(const char *, int);
+	int	 (*dlclose)(void *);
+	void	*(*dlsym)(void *, const char *);
+	int	 (*dladdr)(const void *, struct dl_info *);
+	int	 (*dlctl)(void *, int, void *);
+	char	*(*dlerror)(void);
+	int	 (*dl_iterate_phdr)(int (*)(struct dl_phdr_info *,
+		    size_t, void *), void *);
+};
+
+#define	DL_CB_CUR	0
+typedef	struct dl_cb_0	dl_cb;
+
+/* type of function passed to init functions that returns a dl_cb */
+typedef	const void *dl_cb_cb(int _version);
+
 void	*_dl_allocate_tib(size_t _extra) __dso_public;
 void	_dl_free_tib(void *_tib, size_t _extra) __dso_public;