@@ -41,6 +41,9 @@ ALL_OBJS-y += $(BASEDIR)/xsm/built_in.o
ALL_OBJS-y += $(BASEDIR)/arch/$(TARGET_ARCH)/built_in.o
ALL_OBJS-$(CONFIG_CRYPTO) += $(BASEDIR)/crypto/built_in.o
+# Initialise some variables
+CFLAGS_UBSAN :=
+
ifeq ($(CONFIG_DEBUG),y)
CFLAGS += -O1
else
@@ -138,7 +141,10 @@ $(filter-out %.init.o $(nocov-y),$(obj-y) $(obj-bin-y) $(extra-y)): CFLAGS += $(
endif
ifeq ($(CONFIG_UBSAN),y)
-$(filter-out %.init.o $(noubsan-y),$(obj-y) $(obj-bin-y) $(extra-y)): CFLAGS += -fsanitize=undefined
+CFLAGS_UBSAN += -fsanitize=undefined
+# Any -fno-sanitize= options need to come after any -fsanitize= options
+$(filter-out %.init.o $(noubsan-y),$(obj-y) $(obj-bin-y) $(extra-y)): \
+CFLAGS += $(filter-out -fno-%,$(CFLAGS_UBSAN)) $(filter -fno-%,$(CFLAGS_UBSAN))
endif
ifeq ($(CONFIG_LTO),y)
@@ -57,6 +57,14 @@ endif
$(call cc-option-add,CFLAGS-stack-boundary,CC,-mpreferred-stack-boundary=3)
CFLAGS += $(CFLAGS-stack-boundary)
+ifeq ($(CONFIG_UBSAN),y)
+# Don't enable alignment sanitisation. x86 has efficient unaligned accesses,
+# and various things (ACPI tables, hypercall pages, stubs, etc) are wont-fix.
+# It also causes an as-yet-unidentified crash on native boot before the
+# console starts.
+$(call cc-option-add,CFLAGS_UBSAN,CC,-fno-sanitize=alignment)
+endif
+
# Set up the assembler include path properly for older toolchains.
CFLAGS += -Wa,-I$(BASEDIR)/include
GCC 5 introduced -fsanitize=alignment which is enabled by default by CONFIG_UBSAN. This trips a load of wont-fix cases in the ACPI tables and the hypercall page and stubs writing logic. It also causes the native Xen boot to crash before the console is set up, for an as-yet unidentified reason (most likley a wont-fix case earlier on boot). Disable alignment sanitisation on compilers which would try using it. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Wei Liu <wl@xen.org> CC: Roger Pau Monné <roger.pau@citrix.com> CC: Stefano Stabellini <sstabellini@kernel.org> CC: Julien Grall <julien.grall@arm.com> v2: * Avoid using -fno-sanitize=alignment for ARM v3: * Use CFLAGS_UBSAN, initialised to empty first. * Leave a comment explaining why we use -fno-sanitize=alignment The reason why x86 has a ifeq ($(CONFIG_UBSAN),y) is to avoid yet another cc-option-add evaluated for every translation uint in the default case. This will all go away when we update to a recent version of Kconfig which moves all the toolchain checks into that phase. --- xen/Rules.mk | 8 +++++++- xen/arch/x86/Rules.mk | 8 ++++++++ 2 files changed, 15 insertions(+), 1 deletion(-)