From 91b31c100b5eb30c59f2f78dd10922e7e0b2c6e2 Mon Sep 17 00:00:00 2001
From: Alex Richardson <arichardson@FreeBSD.org>
Date: Tue, 11 Aug 2020 16:47:00 +0000
Subject: [PATCH] Allow linking the kernel with a linker that doesn't support
 -z ifunc-noplt

This can happen when linking with upstream LLD < 9.0.

Reviewed By:	markj
Differential Revision: https://reviews.freebsd.org/D25985
---
 share/mk/bsd.linker.mk | 3 +++
 sys/conf/kern.pre.mk   | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/share/mk/bsd.linker.mk b/share/mk/bsd.linker.mk
index 1a2339390990..5ecd6b8b969c 100644
--- a/share/mk/bsd.linker.mk
+++ b/share/mk/bsd.linker.mk
@@ -94,6 +94,9 @@ ${X_}LINKER_FEATURES+=	riscv-relaxations
 .if ${${X_}LINKER_TYPE} == "lld" && ${${X_}LINKER_VERSION} >= 60000
 ${X_}LINKER_FEATURES+=	retpoline
 .endif
+.if ${${X_}LINKER_TYPE} == "lld" && ${${X_}LINKER_VERSION} >= 90000
+${X_}LINKER_FEATURES+=	ifunc-noplt
+.endif
 .endif
 .else
 # Use LD's values
diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index 2436269c893c..16910042af8b 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -166,9 +166,13 @@ LDFLAGS+=	-z max-page-size=2097152
 .if ${LINKER_TYPE} != "lld"
 LDFLAGS+=	-z common-page-size=4096
 .else
+.if defined(LINKER_FEATURES) && !${LINKER_FEATURES:Mifunc-noplt}
+.warning "Linker ${LD} does not support -z ifunc-noplt -> ifunc calls are unoptimized."
+.else
 LDFLAGS+=	-z notext -z ifunc-noplt
 .endif
 .endif
+.endif  # ${MACHINE_CPUARCH} == "amd64"
 
 .if ${MACHINE_CPUARCH} == "riscv"
 # Hack: Work around undefined weak symbols being out of range when linking with