From ad03b821fbc30395b72af438f5bb41676a5f891d Mon Sep 17 00:00:00 2001 From: Philipp Rudo Date: Tue, 26 Jun 2018 12:24:30 +0200 Subject: [PATCH] s390/purgatory: Fix crash with expoline enabled When the kernel is built with CONFIG_EXPOLINE=y and a compiler with indirect branch mitigation enabled the purgatory crashes. The reason for that is that the macros defined for expoline are used in mem.S. These macros define new sections (.text.__s390x_indirect_*) which are marked executable. Due to the missing linker script those sections are linked to address 0, just as the .text section. In combination with the entry point also being at address 0 this causes the purgatory load code (kernel/kexec_file.c: kexec_purgatory_setup_sechdrs) to update the entry point twice. Thus the old kernel jumps to some 'random' address causing the crash. To fix this turn off expolines for the purgatory. There is no problem with this in this case due to the fact that the purgatory only runs once and the tlb is purged (diag 308) in the end. Fixes: 840798a1f5299 ("s390/kexec_file: Add purgatory") Cc: # 4.17 Signed-off-by: Philipp Rudo Reviewed-by: Heiko Carstens Signed-off-by: Martin Schwidefsky --- arch/s390/purgatory/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile index 1ace023cbdce..704e0f3c244a 100644 --- a/arch/s390/purgatory/Makefile +++ b/arch/s390/purgatory/Makefile @@ -23,6 +23,7 @@ KBUILD_CFLAGS += -Wno-pointer-sign -Wno-sign-compare KBUILD_CFLAGS += -fno-zero-initialized-in-bss -fno-builtin -ffreestanding KBUILD_CFLAGS += -c -MD -Os -m64 -msoft-float KBUILD_CFLAGS += $(call cc-option,-fno-PIE) +KBUILD_AFLAGS := $(filter-out -DCC_USING_EXPOLINE,$(KBUILD_AFLAGS)) $(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE $(call if_changed,ld) -- 2.30.2