Introduce new csu0 variant for -static -pie binaries to use called

rcsu0.o where the initial 'r' is for relocatable. rcsu0.o performs
self-relocation on static pie binaries by calling a slightly modified
copy of ld.so's _dl_boot_bind() in boot.h.

The first arch implementatation is also included for amd64 where
__start calls _dl_boot_bind() and then calls ___start(). Includes
parts from kettenis@ to help get R_X86_64_64 relocations working
and proper handling for undefined weak symbols.

This is the first part of several to get static pie self-relocating
binaries working. binutils, gcc and kernel changes are forthcoming
to complete the solution, then per-arch implementations are needed
for MD_RCRT0_START in csu.

okay kettenis@ pascal@ deraadt@

1 files changed, 8 insertions, 1 deletions

diff --git a/lib/csu/crt0.c b/lib/csu/crt0.c
index aaef64a7a57..965eba66e97 100644
--- a/lib/csu/crt0.c
+++ b/lib/csu/crt0.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: crt0.c,v 1.2 2013/12/12 08:12:08 guenther Exp $	*/
+/*	$OpenBSD: crt0.c,v 1.3 2014/12/22 03:51:08 kurt Exp $	*/
 
 /*
  * Copyright (c) 1995 Christopher G. Demetriou
@@ -35,6 +35,7 @@
 #include <limits.h>
 
 #include "md_init.h"
+#include "boot.h"
 
 /* some defaults */
 #ifndef	MD_START_ARGS
@@ -64,9 +65,15 @@ extern void	_mcleanup(void);
 extern unsigned char _etext, _eprol;
 #endif /* MCRT0 */
 
+#ifdef RCRT0
+#ifdef MD_RCRT0_START
+MD_RCRT0_START;
+#endif
+#else
 #ifdef MD_CRT0_START
 MD_CRT0_START;
 #endif
+#endif
 
 void
 MD_START(MD_START_ARGS)