Merge branch 'kvm-arm64/el2-obj-v4.1' into kvmarm-master/next

Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/kvm/hyp/nvhe/Makefile

@@ -20,8 +20,28 @@ $(obj)/%.hyp.tmp.o: $(src)/%.S FORCE
 $(obj)/%.hyp.o: $(obj)/%.hyp.tmp.o FORCE
 	$(call if_changed,hypcopy)
 
+# Disable reordering functions by GCC (enabled at -O2).
+# This pass puts functions into '.text.*' sections to aid the linker
+# in optimizing ELF layout. See HYPCOPY comment below for more info.
+ccflags-y += $(call cc-option,-fno-reorder-functions)
+
+# The HYPCOPY command uses `objcopy` to prefix all ELF symbol names
+# and relevant ELF section names to avoid clashes with VHE code/data.
+#
+# Hyp code is assumed to be in the '.text' section of the input object
+# files (with the exception of specialized sections such as
+# '.hyp.idmap.text'). This assumption may be broken by a compiler that
+# divides code into sections like '.text.unlikely' so as to optimize
+# ELF layout. HYPCOPY checks that no such sections exist in the input
+# using `objdump`, otherwise they would be linked together with other
+# kernel code and not memory-mapped correctly at runtime.
 quiet_cmd_hypcopy = HYPCOPY $@
-      cmd_hypcopy = $(OBJCOPY)	--prefix-symbols=__kvm_nvhe_		\
+      cmd_hypcopy =							\
+	if $(OBJDUMP) -h $< | grep -F '.text.'; then			\
+		echo "$@: function reordering not supported in nVHE hyp code" >&2; \
+		/bin/false;						\
+	fi;								\
+	$(OBJCOPY) --prefix-symbols=__kvm_nvhe_				\
 		   --rename-section=.text=.hyp.text			\
 		   $< $@