Implement a BSD licensed crtbegin/crtend

These are needed for .ctors/.dtors and .jcr handling. The former needs
all the function pointers to be called in the correct order from the
.init/.fini section. The latter just needs to call a gcj specific function
if it exists with a pointer to the start of the .jcr section.

This is currently disabled until __dso_handle support is added.

Reviewed by:	emaste
MFC after:	1 month
Sponsored by:	DARPA, AFRL
Differential Revision:	https://reviews.freebsd.org/D17587

1 files changed, 99 insertions, 0 deletions

diff --git a/lib/csu/common/crtbegin.c b/lib/csu/common/crtbegin.c
new file mode 100644
index 000000000000..46e604927ac0
--- /dev/null
+++ b/lib/csu/common/crtbegin.c
@@ -0,0 +1,99 @@
+/*-
+ * SPDX-License-Identifier: BSD-1-Clause
+ *
+ * Copyright 2018 Andrew Turner
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+
+#include "crt.h"
+
+typedef void (*crt_func)(void);
+
+/*
+ * On some architectures and toolchains we may need to call the .dtors.
+ * These are called in the order they are in the ELF file.
+ */
+#ifdef HAVE_CTORS
+static void __do_global_dtors_aux(void) __used;
+
+crt_func __CTOR_LIST__[] __section(".ctors") __hidden = {
+	(crt_func)-1
+};
+crt_func __DTOR_LIST__[] __section(".dtors") __hidden = {
+	(crt_func)-1
+};
+
+static void
+__do_global_dtors_aux(void)
+{
+	crt_func fn;
+	int n;
+
+	for (n = 1;; n++) {
+		fn = __DTOR_LIST__[n];
+		if (fn == (crt_func)0 || fn == (crt_func)-1)
+			break;
+		fn();
+	}
+}
+
+asm (
+    ".pushsection .fini		\n"
+    "\t" INIT_CALL_SEQ(__do_global_dtors_aux) "\n"
+    ".popsection		\n"
+);
+#endif
+
+/*
+ * Handler for gcj. These provide a _Jv_RegisterClasses function and fill
+ * out the .jcr section. We just need to call this function with a pointer
+ * to the appropriate section.
+ */
+extern void _Jv_RegisterClasses(void *) __weak_symbol;
+static void register_classes(void) __used;
+
+crt_func __JCR_LIST__[] __section(".jcr") __used __hidden = { };
+
+#ifndef CTORS_CONSTRUCTORS
+__attribute__((constructor))
+#endif
+static void
+register_classes(void)
+{
+
+	if (_Jv_RegisterClasses != NULL && __JCR_LIST__[0] != 0)
+		_Jv_RegisterClasses(__JCR_LIST__);
+}
+
+/*
+ * We can't use constructors when they use the .ctors section as they may be
+ * placed before __CTOR_LIST__.
+ */
+#ifdef CTORS_CONSTRUCTORS
+asm (
+    ".pushsection .init		\n"
+    "\t" INIT_CALL_SEQ(register_classes) "\n"
+    ".popsection		\n"
+);
+#endif