This is a note to let you know that I've just added the patch titled
ARM: kvm: fix building with gcc-8
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
arm-kvm-fix-building-with-gcc-8.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 67870eb1204223598ea6d8a4467b482e9f5875b5 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@xxxxxxxx>
Date: Fri, 2 Feb 2018 16:07:34 +0100
Subject: ARM: kvm: fix building with gcc-8
From: Arnd Bergmann <arnd@xxxxxxxx>
commit 67870eb1204223598ea6d8a4467b482e9f5875b5 upstream.
In banked-sr.c, we use a top-level '__asm__(".arch_extension virt")'
statement to allow compilation of a multi-CPU kernel for ARMv6
and older ARMv7-A that don't normally support access to the banked
registers.
This is considered to be a programming error by the gcc developers
and will no longer work in gcc-8, where we now get a build error:
/tmp/cc4Qy7GR.s:34: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_usr'
/tmp/cc4Qy7GR.s:41: Error: Banked registers are not available with this architecture. -- `mrs r3,ELR_hyp'
/tmp/cc4Qy7GR.s:55: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_svc'
/tmp/cc4Qy7GR.s:62: Error: Banked registers are not available with this architecture. -- `mrs r3,LR_svc'
/tmp/cc4Qy7GR.s:69: Error: Banked registers are not available with this architecture. -- `mrs r3,SPSR_svc'
/tmp/cc4Qy7GR.s:76: Error: Banked registers are not available with this architecture. -- `mrs r3,SP_abt'
Passign the '-march-armv7ve' flag to gcc works, and is ok here, because
we know the functions won't ever be called on pre-ARMv7VE machines.
Unfortunately, older compiler versions (4.8 and earlier) do not understand
that flag, so we still need to keep the asm around.
Backporting to stable kernels (4.6+) is needed to allow those to be built
with future compilers as well.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84129
Fixes: 33280b4cd1dc ("ARM: KVM: Add banked registers save/restore")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kvm/hyp/Makefile | 5 +++++
arch/arm/kvm/hyp/banked-sr.c | 4 ++++
2 files changed, 9 insertions(+)
--- a/arch/arm/kvm/hyp/Makefile
+++ b/arch/arm/kvm/hyp/Makefile
@@ -7,6 +7,8 @@ ccflags-y += -fno-stack-protector -DDISA
KVM=../../../../virt/kvm
+CFLAGS_ARMV7VE :=$(call cc-option, -march=armv7ve)
+
obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v2-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/vgic-v3-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/hyp/timer-sr.o
@@ -15,7 +17,10 @@ obj-$(CONFIG_KVM_ARM_HOST) += tlb.o
obj-$(CONFIG_KVM_ARM_HOST) += cp15-sr.o
obj-$(CONFIG_KVM_ARM_HOST) += vfp.o
obj-$(CONFIG_KVM_ARM_HOST) += banked-sr.o
+CFLAGS_banked-sr.o += $(CFLAGS_ARMV7VE)
+
obj-$(CONFIG_KVM_ARM_HOST) += entry.o
obj-$(CONFIG_KVM_ARM_HOST) += hyp-entry.o
obj-$(CONFIG_KVM_ARM_HOST) += switch.o
+CFLAGS_switch.o += $(CFLAGS_ARMV7VE)
obj-$(CONFIG_KVM_ARM_HOST) += s2-setup.o
--- a/arch/arm/kvm/hyp/banked-sr.c
+++ b/arch/arm/kvm/hyp/banked-sr.c
@@ -20,6 +20,10 @@
#include <asm/kvm_hyp.h>
+/*
+ * gcc before 4.9 doesn't understand -march=armv7ve, so we have to
+ * trick the assembler.
+ */
__asm__(".arch_extension virt");
void __hyp_text __banked_save_state(struct kvm_cpu_context *ctxt)
Patches currently in stable-queue which might be from arnd@xxxxxxxx are
queue-4.15/ipv6-sit-work-around-bogus-gcc-8-wrestrict-warning.patch
queue-4.15/arm-kvm-fix-building-with-gcc-8.patch
queue-4.15/arm-orion-fix-orion_ge00_switch_board_info-initialization.patch