From adc0b7fbf6fe9967505c0254d9535ec7288186ae Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Mon, 28 Sep 2015 22:47:42 +0200 Subject: s390/boot/decompression: disable floating point in decompressor my gcc 5.1 used an ldgr instruction with a register != 0,2,4,6 for spilling/filling into a floating point register in our decompressor. This will cause an AFP-register data exception as the decompressor did not setup the additional floating point registers via cr0. That causes a program check loop that looked like a hang with one "Uncompressing Linux... " message (directly booted via kvm) or a loop of "Uncompressing Linux... " messages (when booted via zipl boot loader). The offending code in my build was 48e400: e3 c0 af ff ff 71 lay %r12,-1(%r10) -->48e406: b3 c1 00 1c ldgr %f1,%r12 48e40a: ec 6c 01 22 02 7f clij %r6,2,12,0x48e64e but gcc could do spilling into an fpr at any function. We can simply disable floating point support at that early stage. Signed-off-by: Christian Borntraeger Acked-by: Heiko Carstens Cc: stable@vger.kernel.org --- arch/s390/boot/compressed/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/s390/boot/compressed/Makefile b/arch/s390/boot/compressed/Makefile index d4788111c161..fac6ac9790fa 100644 --- a/arch/s390/boot/compressed/Makefile +++ b/arch/s390/boot/compressed/Makefile @@ -10,7 +10,7 @@ targets += misc.o piggy.o sizes.h head.o KBUILD_CFLAGS := -m64 -D__KERNEL__ $(LINUX_INCLUDE) -O2 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING -KBUILD_CFLAGS += $(cflags-y) -fno-delete-null-pointer-checks +KBUILD_CFLAGS += $(cflags-y) -fno-delete-null-pointer-checks -msoft-float KBUILD_CFLAGS += $(call cc-option,-mpacked-stack) KBUILD_CFLAGS += $(call cc-option,-ffreestanding) -- cgit v1.2.3