Declare the symbols that label the .ctors, .dtors, .eh_frame, and .jcr

sections as extern hidden arrays of indefinite size, so that the compiler
(well, clang) doesn't believe it knows the exact contents and thus optimize
things into infinite loops.  Actually set the symbols to be in the sections
and insert the leading and trailing values via __asm().

Problem pointed out by patrick@
testing and ok kettenis@

7 files changed, 95 insertions, 39 deletions

diff --git a/lib/csu/arm/md_init.h b/lib/csu/arm/md_init.h
index 9e9aaa1fa60..30e7c991473 100644
--- a/lib/csu/arm/md_init.h
+++ b/lib/csu/arm/md_init.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: md_init.h,v 1.9 2016/10/03 22:13:30 kettenis Exp $ */
+/* $OpenBSD: md_init.h,v 1.10 2017/01/21 00:45:13 guenther Exp $ */
 
 /*-
  * Copyright (c) 2001 Ross Harvey
@@ -33,6 +33,28 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 
+/*
+ * arm overrides these because it uses %progbits instead of @progbits
+ */
+#define MD_DATA_SECTION_FLAGS_SYMBOL(section, flags, type, symbol)	\
+	extern __dso_hidden type symbol[];				\
+	__asm("	.section "section",\""flags"\",%progbits		\n" \
+	"	.balign 4						\n" \
+	#symbol":							\n" \
+	"	.previous")
+#define MD_DATA_SECTION_SYMBOL_VALUE(section, type, symbol, value)	\
+	extern __dso_hidden type symbol[];				\
+	__asm("	.section "section",\"aw\",%progbits			\n" \
+	"	.balign 4						\n" \
+	#symbol":							\n" \
+	"	.int "#value"						\n" \
+	"	.previous")
+#define MD_DATA_SECTION_FLAGS_VALUE(section, flags, value)		\
+	__asm("	.section "section",\""flags"\",%progbits		\n" \
+	"	.balign 4						\n" \
+	"	.int "#value"						\n" \
+	"	.previous")
+
 #ifdef __PIC__
 	/* This nastyness derived from gcc3 output */
 #define MD_SECT_CALL_FUNC(section, func) \
diff --git a/lib/csu/crtbegin.c b/lib/csu/crtbegin.c
index 534f4dfb4a1..3d359e62e59 100644
--- a/lib/csu/crtbegin.c
+++ b/lib/csu/crtbegin.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: crtbegin.c,v 1.21 2016/12/22 09:32:04 kettenis Exp $	*/
+/*	$OpenBSD: crtbegin.c,v 1.22 2017/01/21 00:45:13 guenther Exp $	*/
 /*	$NetBSD: crtbegin.c,v 1.1 1996/09/12 16:59:03 cgd Exp $	*/
 
 /*
@@ -56,15 +56,13 @@ void __register_frame_info(const void *begin, struct dwarf2_eh_object *ob)
 {
 }
 
-static const char __EH_FRAME_BEGIN__[]
-    __attribute__((section(".eh_frame"), aligned(4))) = { };
+MD_DATA_SECTION_FLAGS_SYMBOL(".eh_frame", "a", const void *, __EH_FRAME_BEGIN__);
 
 /*
  * java class registration hooks
  */
 
-static void *__JCR_LIST__[]
-    __attribute__((section(".jcr"), aligned(sizeof(void*)))) = { };
+MD_DATA_SECTION_FLAGS_SYMBOL(".jcr", "aw", void *, __JCR_LIST__);
 
 extern void _Jv_RegisterClasses (void *)
     __attribute__((weak));
@@ -83,11 +81,8 @@ __asm(".hidden  __dso_handle");
 
 long __guard_local __dso_hidden __attribute__((section(".openbsd.randomdata")));
 
-
-static init_f __CTOR_LIST__[1]
-    __attribute__((section(".ctors"))) = { (void *)-1 };	/* XXX */
-static init_f __DTOR_LIST__[1]
-    __attribute__((section(".dtors"))) = { (void *)-1 };	/* XXX */
+MD_DATA_SECTION_SYMBOL_VALUE(".ctors", init_f, __CTOR_LIST__, -1);
+MD_DATA_SECTION_SYMBOL_VALUE(".dtors", init_f, __DTOR_LIST__, -1);
 
 static void	__dtors(void) __used;
 static void	__ctors(void) __used;
diff --git a/lib/csu/crtbeginS.c b/lib/csu/crtbeginS.c
index f97d30f22b0..7cc8252e58c 100644
--- a/lib/csu/crtbeginS.c
+++ b/lib/csu/crtbeginS.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: crtbeginS.c,v 1.16 2015/04/07 01:27:06 guenther Exp $	*/
+/*	$OpenBSD: crtbeginS.c,v 1.17 2017/01/21 00:45:13 guenther Exp $	*/
 /*	$NetBSD: crtbegin.c,v 1.1 1996/09/12 16:59:03 cgd Exp $	*/
 
 /*
@@ -50,8 +50,7 @@
  * java class registration hooks
  */
 
-static void *__JCR_LIST__[]
-    __attribute__((section(".jcr"), aligned(sizeof(void*)))) = { };
+MD_DATA_SECTION_FLAGS_SYMBOL(".jcr", "aw", void *, __JCR_LIST__);
 
 extern void _Jv_RegisterClasses (void *)
     __attribute__((weak));
@@ -94,11 +93,8 @@ pthread_atfork(void (*prep)(void), void (*parent)(void), void (*child)(void))
 /* hppa doesn't permit directives in first column, so space after newline */
 asm(".hidden pthread_atfork\n .weak pthread_atfork");
 
-
-static init_f __CTOR_LIST__[1]
-    __attribute__((section(".ctors"))) = { (void *)-1 };	/* XXX */
-static init_f __DTOR_LIST__[1]
-    __attribute__((section(".dtors"))) = { (void *)-1 };	/* XXX */
+MD_DATA_SECTION_SYMBOL_VALUE(".ctors", init_f, __CTOR_LIST__, -1);
+MD_DATA_SECTION_SYMBOL_VALUE(".dtors", init_f, __DTOR_LIST__, -1);
 
 static void	__dtors(void) __used;
 static void	__ctors(void) __used;
diff --git a/lib/csu/crtend.c b/lib/csu/crtend.c
index 6d2ea472a74..566fa0652d6 100644
--- a/lib/csu/crtend.c
+++ b/lib/csu/crtend.c
@@ -1,20 +1,14 @@
-/*	$OpenBSD: crtend.c,v 1.11 2015/04/04 18:05:05 guenther Exp $	*/
+/*	$OpenBSD: crtend.c,v 1.12 2017/01/21 00:45:13 guenther Exp $	*/
 /*	$NetBSD: crtend.c,v 1.1 1996/09/12 16:59:04 cgd Exp $	*/
 
 #include <sys/types.h>
 #include "md_init.h"
 #include "extern.h"
 
-static init_f __CTOR_LIST__[1]
-    __used __attribute__((section(".ctors"))) = { (void *)0 };	/* XXX */
-static init_f __DTOR_LIST__[1]
-    __used __attribute__((section(".dtors"))) = { (void *)0 };	/* XXX */
-
-static const int __EH_FRAME_END__[]
-    __used __attribute__((section(".eh_frame"), aligned(4))) = { 0 };
-
-static void * __JCR_END__[]
-    __used __attribute__((section(".jcr"), aligned(sizeof(void*)))) = { 0 };
+MD_DATA_SECTION_FLAGS_VALUE(".ctors", "aw", 0);
+MD_DATA_SECTION_FLAGS_VALUE(".dtors", "aw", 0);
+MD_DATA_SECTION_FLAGS_VALUE(".eh_frame", "a", 0);
+MD_DATA_SECTION_FLAGS_VALUE(".jcr", "aw", 0);
 
 MD_SECTION_EPILOGUE(".init");
 MD_SECTION_EPILOGUE(".fini");
diff --git a/lib/csu/crtendS.c b/lib/csu/crtendS.c
index d83e6160232..a58b304587a 100644
--- a/lib/csu/crtendS.c
+++ b/lib/csu/crtendS.c
@@ -1,17 +1,13 @@
-/*	$OpenBSD: crtendS.c,v 1.9 2015/04/04 18:05:05 guenther Exp $	*/
+/*	$OpenBSD: crtendS.c,v 1.10 2017/01/21 00:45:13 guenther Exp $	*/
 /*	$NetBSD: crtend.c,v 1.1 1997/04/16 19:38:24 thorpej Exp $	*/
 
 #include <sys/types.h>
 #include "md_init.h"
 #include "extern.h"
 
-static init_f __CTOR_LIST__[1]
-    __used __attribute__((section(".ctors"))) = { (void *)0 };	/* XXX */
-static init_f __DTOR_LIST__[1]
-    __used __attribute__((section(".dtors"))) = { (void *)0 };	/* XXX */
-
-static void * __JCR_END__[]
-    __used __attribute__((section(".jcr"), aligned(sizeof(void*)))) = { 0 };
+MD_DATA_SECTION_FLAGS_VALUE(".ctors", "aw", 0);
+MD_DATA_SECTION_FLAGS_VALUE(".dtors", "aw", 0);
+MD_DATA_SECTION_FLAGS_VALUE(".jcr", "aw", 0);
 
 MD_SECTION_EPILOGUE(".init");
 MD_SECTION_EPILOGUE(".fini");
diff --git a/lib/csu/extern.h b/lib/csu/extern.h
index 53d49a36788..775438fde0c 100644
--- a/lib/csu/extern.h
+++ b/lib/csu/extern.h
@@ -21,3 +21,35 @@ extern void __init(void);
 extern int main(int argc, char *argv[], char *envp[]);
 
 typedef void (*init_f)(void);
+
+/*
+ * Provide default implementations of these.  Only archs with weird
+ * ASM stuff (hppa, arm) need to override them
+ */
+#ifndef MD_DATA_SECTION_FLAGS_SYMBOL
+# ifdef __LP64__
+#  define VALUE_ALIGN		".balign 8"
+#  define VALUE_DIRECTIVE	".quad"
+# else
+#  define VALUE_ALIGN		".balign 4"
+#  define VALUE_DIRECTIVE	".int"
+# endif
+# define MD_DATA_SECTION_FLAGS_SYMBOL(section, flags, type, symbol)	\
+	extern __dso_hidden type symbol[];				\
+	__asm("	.section "section",\""flags"\",@progbits		\n" \
+	"	"VALUE_ALIGN"						\n" \
+	#symbol":							\n" \
+	"	.previous")
+# define MD_DATA_SECTION_SYMBOL_VALUE(section, type, symbol, value)	\
+	extern __dso_hidden type symbol[];				\
+	__asm("	.section "section",\"aw\",@progbits			\n" \
+	"	"VALUE_ALIGN"						\n" \
+	#symbol":							\n" \
+	"	"VALUE_DIRECTIVE" "#value"				\n" \
+	"	.previous")
+# define MD_DATA_SECTION_FLAGS_VALUE(section, flags, value)		\
+	__asm("	.section "section",\""flags"\",@progbits		\n" \
+	"	"VALUE_ALIGN"						\n" \
+	"	"VALUE_DIRECTIVE" "#value"				\n" \
+	"	.previous")
+#endif
diff --git a/lib/csu/hppa/md_init.h b/lib/csu/hppa/md_init.h
index 92ccd465850..f916a6a913d 100644
--- a/lib/csu/hppa/md_init.h
+++ b/lib/csu/hppa/md_init.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: md_init.h,v 1.9 2016/03/20 02:32:39 guenther Exp $ */
+/* $OpenBSD: md_init.h,v 1.10 2017/01/21 00:45:13 guenther Exp $ */
 
 /*
  * Copyright (c) 2003 Dale Rahn. All rights reserved.
@@ -24,6 +24,27 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */  
 
+/*
+ * hppa overrides these because it has different label syntax
+ */
+#define MD_DATA_SECTION_FLAGS_SYMBOL(section, flags, type, symbol)	\
+	extern __dso_hidden type symbol[];				\
+	__asm("	.section "section",\""flags"\",@progbits		\n" \
+	"	.balign 4						\n" \
+	#symbol"							\n" \
+	"	.previous")
+#define MD_DATA_SECTION_SYMBOL_VALUE(section, type, symbol, value)	\
+	extern __dso_hidden type symbol[];				\
+	__asm("	.section "section",\"aw\",@progbits			\n" \
+	"	.balign 4						\n" \
+	#symbol"							\n" \
+	"	.int "#value"						\n" \
+	"	.previous")
+#define MD_DATA_SECTION_FLAGS_VALUE(section, flags, value)		\
+	__asm("	.section "section",\""flags"\",@progbits		\n" \
+	"	.balign 4						\n" \
+	"	.int "#value"						\n" \
+	"	.previous")
 
 #ifdef __PIC__
 #define MD_SECT_CALL_FUNC(section, func)			\