The patch below does not apply to the 4.16-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 6cf09958f32b9667bb3ebadf74367c791112771b Mon Sep 17 00:00:00 2001

From: Martin Schwidefsky schwidefsky@de.ibm.com Date: Fri, 20 Apr 2018 12:48:52 +0200 Subject: [PATCH] s390: correct module section names for expoline code revert

The main linker script vmlinux.lds.S for the kernel image merges the expoline code patch tables into two section ".nospec_call_table" and ".nospec_return_table". This is *not* done for the modules, there the sections retain their original names as generated by gcc: ".s390_indirect_call", ".s390_return_mem" and ".s390_return_reg".

The module_finalize code has to check for the compiler generated section names, otherwise no code patching is done. This slows down the module code in case of "spectre_v2=off".

Cc: stable@vger.kernel.org # 4.16 Fixes: f19fbd5ed6 ("s390: introduce execute-trampolines for branches") Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com

diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c index 5a83be955c70..0dc8ac8548ee 100644 --- a/arch/s390/kernel/module.c +++ b/arch/s390/kernel/module.c @@ -465,11 +465,11 @@ int module_finalize(const Elf_Ehdr *hdr, apply_alternatives(aseg, aseg + s->sh_size);

if (IS_ENABLED(CONFIG_EXPOLINE) && - (!strcmp(".nospec_call_table", secname))) + (!strncmp(".s390_indirect", secname, 14))) nospec_revert(aseg, aseg + s->sh_size);

if (IS_ENABLED(CONFIG_EXPOLINE) && - (!strcmp(".nospec_return_table", secname))) + (!strncmp(".s390_return", secname, 12))) nospec_revert(aseg, aseg + s->sh_size); }