If gapdummy.c is compiled with -fcf-protection=branch, clang 13

creates and additional section .note.gnu.property.  With that the
linker creates a section .plt in gap.o.  In the end, a .plt section
is also present in the kernel.  There it does not make sense.  As
a quick fix explcitly disable cf protection when compiling gapdummy.c
to gapdummy.o.  There is no code to protect anyway.
OK deraadt@

diff --git a/sys/arch/amd64/conf/Makefile.amd64 b/sys/arch/amd64/conf/Makefile.amd64
index 7fd82c3..7759b87 100644 (file)
--- a/sys/arch/amd64/conf/Makefile.amd64
+++ b/sys/arch/amd64/conf/Makefile.amd64
@@ -1,4 +1,4 @@
-#      $OpenBSD: Makefile.amd64,v 1.131 2023/04/17 01:14:24 deraadt Exp $
+#      $OpenBSD: Makefile.amd64,v 1.132 2023/04/21 13:24:20 bluhm Exp $
 
 # For instructions on building kernels consult the config(8) and options(4)
 # manual pages.
@@ -177,7 +177,7 @@ ld.script: ${_machdir}/conf/ld.script
 
 gapdummy.o:
        echo '__asm(".section .rodata,\"a\"");' > gapdummy.c
-       ${CC} -c ${CFLAGS} ${CPPFLAGS} gapdummy.c -o $@
+       ${CC} -c ${CFLAGS} ${CPPFLAGS} -fcf-protection=none gapdummy.c -o $@
 
 makegap.sh:
        cp $S/conf/makegap.sh $@