Fix build for arm with gcc 8

2 files changed, 166 insertions, 0 deletions

diff --git a/arm-gcc-8-build-fixes.patch b/arm-gcc-8-build-fixes.patch
new file mode 100644
index 000000000..82b3165c3
--- /dev/null
+++ b/arm-gcc-8-build-fixes.patch
@@ -0,0 +1,164 @@
+From patchwork Fri Feb  2 15:07:34 2018
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [1/2] ARM: kvm: fix building with gcc-8
+From: Arnd Bergmann <arnd@arndb.de>
+X-Patchwork-Id: 10196985
+Message-Id: <20180202150756.420422-1-arnd@arndb.de>
+To: Christoffer Dall <christoffer.dall@linaro.org>,
+ Marc Zyngier <marc.zyngier@arm.com>, Russell King <linux@armlinux.org.uk>
+Cc: Nicolas Pitre <nico@linaro.org>, Andi Kleen <ak@linux.intel.com>,
+ Richard Earnshaw <rearnsha@gcc.gnu.org>,
+ Tamar Christina <tnfchris@gcc.gnu.org>,
+ Arnd Bergmann <arnd@arndb.de>, stable@vger.kernel.org,
+ Julien Thierry <julien.thierry@arm.com>,
+ linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu,
+ linux-kernel@vger.kernel.org
+Date: Fri,  2 Feb 2018 16:07:34 +0100
+
+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@vger.kernel.org
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
+---
+ arch/arm/kvm/hyp/Makefile    | 5 +++++
+ arch/arm/kvm/hyp/banked-sr.c | 4 ++++
+ 2 files changed, 9 insertions(+)
+
+diff --git a/arch/arm/kvm/hyp/Makefile b/arch/arm/kvm/hyp/Makefile
+index 5638ce0c9524..63d6b404d88e 100644
+--- a/arch/arm/kvm/hyp/Makefile
++++ b/arch/arm/kvm/hyp/Makefile
+@@ -7,6 +7,8 @@ ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING
+ 
+ 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
+diff --git a/arch/arm/kvm/hyp/banked-sr.c b/arch/arm/kvm/hyp/banked-sr.c
+index 111bda8cdebd..be4b8b0a40ad 100644
+--- 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)
+From patchwork Fri Feb  2 15:07:35 2018
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+Subject: [2/2] ARM: xscale: fix gcc-8 build
+From: Arnd Bergmann <arnd@arndb.de>
+X-Patchwork-Id: 10196991
+Message-Id: <20180202150756.420422-2-arnd@arndb.de>
+To: Russell King <linux@armlinux.org.uk>
+Cc: Nicolas Pitre <nico@linaro.org>, Andi Kleen <ak@linux.intel.com>,
+ Richard Earnshaw <rearnsha@gcc.gnu.org>,
+ Tamar Christina <tnfchris@gcc.gnu.org>, Arnd Bergmann <arnd@arndb.de>,
+ linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
+Date: Fri,  2 Feb 2018 16:07:35 +0100
+
+We use a hack in xscale-cp0.c to allow building it for ARMv4 while
+also using ARMv5TE and iWMMXt specific inline assembly, by
+adding a top-level asm statement.
+
+Unfortunately that hack no longer works with gcc-8, since it will
+revert back to the normal architecture. The recommended way of
+handling this is to use __attribute__((target("armv5te"))) on the
+functions that need it, or #pragma GCC target("arch=armv5te").
+Either of those work with gcc-8, but not earlier versions, and
+it seems worse to combine that with the old hack.
+
+Instead, this adds the .arch statement to each inline assembler
+statement that needs it individually. That is also slightly uglier
+than the previous hack, but it works with all compiler versions
+and documents better why we need the override in the first place.
+
+Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84129
+Signed-off-by: Arnd Bergmann <arnd@arndb.de>
+Acked-by: Nicolas Pitre <nico@linaro.org>
+---
+ arch/arm/kernel/xscale-cp0.c | 7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+
+diff --git a/arch/arm/kernel/xscale-cp0.c b/arch/arm/kernel/xscale-cp0.c
+index 77a2eef72115..e06a2f6dac4f 100644
+--- a/arch/arm/kernel/xscale-cp0.c
++++ b/arch/arm/kernel/xscale-cp0.c
+@@ -17,11 +17,10 @@
+ #include <asm/thread_notify.h>
+ #include <asm/cputype.h>
+ 
+-asm("	.arch armv5te\n");
+-
+ static inline void dsp_save_state(u32 *state)
+ {
+ 	__asm__ __volatile__ (
++		".arch	armv5te\n\t"
+ 		"mrrc	p0, 0, %0, %1, c0\n"
+ 		: "=r" (state[0]), "=r" (state[1]));
+ }
+@@ -29,6 +28,7 @@ static inline void dsp_save_state(u32 *state)
+ static inline void dsp_load_state(u32 *state)
+ {
+ 	__asm__ __volatile__ (
++		".arch	armv5te\n\t"
+ 		"mcrr	p0, 0, %0, %1, c0\n"
+ 		: : "r" (state[0]), "r" (state[1]));
+ }
+@@ -134,7 +134,8 @@ static int __init cpu_has_iwmmxt(void)
+ 	 *	tmrrc	%0, %1, wR0
+ 	 */
+ 	__asm__ __volatile__ (
+-		"mcrr	p0, 0, %2, %3, c0\n"
++		".arch	armv5te\n\t"
++		"mcrr	p0, 0, %2, %3, c0\n\t"
+ 		"mrrc	p0, 0, %0, %1, c0\n"
+ 		: "=r" (lo), "=r" (hi)
+ 		: "r" (0), "r" (0x100));
diff --git a/kernel.spec b/kernel.spec
index 8a5d8d428..3419a6c95 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -507,6 +507,8 @@ Patch001: 0001-tools-lib-subcmd-pager.c-do-not-alias-select-params.patch
 # ongoing complaint, full discussion delayed until ksummit/plumbers
 Patch002: 0001-iio-Use-event-header-from-kernel-tree.patch
 
+Patch003: arm-gcc-8-build-fixes.patch
+
 %if !%{nopatches}
 
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