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@

3 files changed, 18 insertions, 6 deletions

diff --git a/lib/csu/boot.h b/lib/csu/boot.h
index c899af9303b..6ec5256bb06 100644
--- a/lib/csu/boot.h
+++ b/lib/csu/boot.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: boot.h,v 1.29 2018/11/22 21:37:29 guenther Exp $ */
+/*	$OpenBSD: boot.h,v 1.30 2019/05/10 13:29:21 guenther Exp $ */
 
 /*
  * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
@@ -81,6 +81,14 @@ struct boot_dyn {
 #endif
 };
 
+static void *relro_addr;
+static size_t relro_size;
+#define RCRT0_RELRO()							\
+	do {								\
+		if (relro_addr != NULL && relro_size != 0)		\
+			mprotect(relro_addr, relro_size, PROT_READ);	\
+	} while (0)
+
 /*
  * Local decls.
  */
@@ -220,8 +228,8 @@ _dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynamicp)
 			break;
 #endif
 		case PT_GNU_RELRO:
-			mprotect((void *)(phdp->p_vaddr + loff), phdp->p_memsz,
-			    PROT_READ);
+			relro_addr = (void *)(phdp->p_vaddr + loff);
+			relro_size = phdp->p_memsz;
 			/*
 			 * GNU_RELRO (a) covers the GOT, and (b) comes after
 			 * all LOAD sections, so if we found it then we're done
diff --git a/lib/csu/crt0.c b/lib/csu/crt0.c
index ac2966b5490..2c113e73428 100644
--- a/lib/csu/crt0.c
+++ b/lib/csu/crt0.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: crt0.c,v 1.13 2019/05/08 20:27:29 guenther Exp $	*/
+/*	$OpenBSD: crt0.c,v 1.14 2019/05/10 13:29:21 guenther Exp $	*/
 
 /*
  * Copyright (c) 1995 Christopher G. Demetriou
@@ -49,6 +49,9 @@ static void		___start(MD_START_ARGS) __used;
 #ifndef	MD_EPROL_LABEL
 #define	MD_EPROL_LABEL	__asm("  .text\n_eprol:")
 #endif
+#ifndef RCRT0_RELRO
+#define RCRT0_RELRO()	do {} while (0)
+#endif
 
 char	***_csu_finish(char **_argv, char **_envp, void (*_cleanup)(void));
 
@@ -89,6 +92,7 @@ ___start(MD_START_ARGS)
 		size = __preinit_array_end - __preinit_array_start;
 		for (i = 0; i < size; i++)
 			__preinit_array_start[i](argc, argv, envp, NULL);
+		RCRT0_RELRO();
 		size = __init_array_end - __init_array_start;
 		for (i = 0; i < size; i++)
 			__init_array_start[i](argc, argv, envp, NULL);
diff --git a/lib/csu/extern.h b/lib/csu/extern.h
index 5cc17413c8a..92dc12a0437 100644
--- a/lib/csu/extern.h
+++ b/lib/csu/extern.h
@@ -17,8 +17,8 @@
 void	__init(void) __dso_hidden;
 int	main(int argc, char *argv[], char *envp[]);
 
-struct dl_cb;
-typedef void (*initarray_f)(int, char **, char **, const struct dl_cb *);
+typedef const void *dl_cb_cb(int);
+typedef void (*initarray_f)(int, char **, char **, dl_cb_cb *);
 typedef void (*init_f)(void);
 
 /*