From: Paul E. Murphy <murp@ibm.com>
Date: Fri, 19 Aug 2022 14:20:02 +0000 (-0500)
Subject: [release-branch.go1.18] runtime: fix ppc64 startup on newer linux kernels
X-Git-Tag: go1.18.6~3
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=da8a3502014c8edf84492267cba1bfdd8e313b3e;p=gostls13.git

[release-branch.go1.18] runtime: fix ppc64 startup on newer linux kernels

R0 needs to be cleared at startup as it may not always be cleared
by the kernel on newer kernels.

Fixes #54664

Change-Id: Id7055699aaa8d8b193b7e3e784f075ce29ac3f1d
Reviewed-on: https://go-review.googlesource.com/c/go/+/424927
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Paul Murphy <murp@ibm.com>
Reviewed-on: https://go-review.googlesource.com/c/go/+/425369
Reviewed-by: Ian Lance Taylor <iant@google.com>
---

diff --git a/src/runtime/rt0_linux_ppc64.s b/src/runtime/rt0_linux_ppc64.s
index 897d61052a..c9300a9caf 100644
--- a/src/runtime/rt0_linux_ppc64.s
+++ b/src/runtime/rt0_linux_ppc64.s
@@ -22,6 +22,7 @@ TEXT _main<>(SB),NOSPLIT,$-8
 	// There is no TLS base pointer.
 	//
 	// TODO(austin): Support ABI v1 dynamic linking entry point
+	XOR	R0, R0 // Note, newer kernels may not always set R0 to 0.
 	MOVD	$runtime·rt0_go(SB), R12
 	MOVD	R12, CTR
 	MOVBZ	runtime·iscgo(SB), R5