From: kettenis <kettenis@openbsd.org>
Date: Mon, 9 Jan 2023 13:45:55 +0000 (+0000)
Subject: In preparation for upcoming execute-only support, change the magic branch
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=4bd9ff11abf2fd7ac677cb497a9eea39a0dc4060;p=openbsd

In preparation for upcoming execute-only support, change the magic branch
instruction used by __canonicalize_funcptr_for_compare() from "bl" into "b".
This allows __canonicalize_funcptr_for_compare() to execute the branch
instead of decoding the instruction to find the address of _dl_bind().

This is the first step in the transition to a new ABI.  Once an updated
ld.so has been installed, we can change __canonicalize_funcptr_for_compare()
(which lives in libgcc) and rebuild everything with a new libgcc.  Only
then we can actually make ld.so executable-only.

ok deraadt@, miod@
---

diff --git a/libexec/ld.so/hppa/ldasm.S b/libexec/ld.so/hppa/ldasm.S
index 13621295ef4..4d19f9bfecb 100644
--- a/libexec/ld.so/hppa/ldasm.S
+++ b/libexec/ld.so/hppa/ldasm.S
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ldasm.S,v 1.24 2017/08/27 21:59:52 deraadt Exp $	*/
+/*	$OpenBSD: ldasm.S,v 1.25 2023/01/09 13:45:55 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2004 Michael Shalayeff
@@ -113,7 +113,7 @@ EXIT(_hppa_dl_set_dp)
  * __canonicalize_funcptr_for_compare() function to fixup relocations
  * in order to do function pointer comparisons.
  */
-	bl	_dl_bind, rp
+	b	_dl_bind
 
 ENTRY(_dl_bind_start,32)
 	copy	r3, r1