[PATCH v8 06/29] KVM: Move export symbol check macros to Makefile.kvm

[Steffen Eiden]

The EXPORT_SYMBOL_GPL/EXPORT_SYMBOL enforcement logic in
arch/x86/kvm/Makefile is useful for any KVM architecture wanting to
restrict the exported symbols. Move the check macros to
virt/kvm/Makefile.kvm so they can be shared.

Arch Makefiles only need to set kvm_exports_allowed to a space-separated
list of symbols that are permitted and then call kvm_check_exports for
each symbol type they want to enforce.

No functional change.

Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
---
 arch/x86/kvm/Makefile | 49 +++++++++----------------------------------
 virt/kvm/Makefile.kvm | 33 +++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 39 deletions(-)

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index c6bf463f5032..1bfd630c0767 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -54,43 +54,14 @@ clean-files += kvm-asm-offsets.h
 # Only a handful of exports intended for other modules (VFIO, KVMGT) should
 # use EXPORT_SYMBOL_GPL, and EXPORT_SYMBOL should never be used.
 ifdef CONFIG_KVM_X86
-# Search recursively for whole words and print line numbers.  Filter out the
-# allowed set of exports, i.e. those that are intended for external usage.
-exports_grep_trailer := --include='*.[ch]' -nrw $(srctree)/virt/kvm $(srctree)/arch/x86/kvm | \
-			grep -v -e kvm_page_track_register_notifier \
-				-e kvm_page_track_unregister_notifier \
-				-e kvm_write_track_add_gfn \
-				-e kvm_write_track_remove_gfn \
-				-e kvm_file_to_kvm_fn
-
-# Force grep to emit a goofy group separator that can in turn be replaced with
-# the above newline macro (newlines in Make are a nightmare).  Note, grep only
-# prints the group separator when N lines of context are requested via -C,
-# a.k.a. --NUM.  Simply request zero lines.  Print the separator only after
-# filtering out expected exports to avoid extra newlines in the error message.
-define get_kvm_exports
-$(shell grep "$(1)" -C0 $(exports_grep_trailer) | grep "$(1)" -C0 --group-separator="!SEP!")
-endef
-
-define check_kvm_exports
-nr_kvm_exports := $(shell grep "$(1)" $(exports_grep_trailer) | wc -l)
-
-ifneq (0,$$(nr_kvm_exports))
-$$(error ERROR ***\
-$$(newline)found $$(nr_kvm_exports) unwanted occurrences of $(1):\
-$$(newline)  $(subst !SEP!,$$(newline) ,$(call get_kvm_exports,$(1)))\
-$$(newline)in directories:\
-$$(newline)  $(srctree)/arch/x86/kvm\
-$$(newline)  $(srctree)/virt/kvm\
-$$(newline)Use EXPORT_SYMBOL_FOR_KVM_INTERNAL, not $(1))
-endif # nr_kvm_exports != 0
-undefine nr_kvm_exports
-endef # check_kvm_exports
-
-$(eval $(call check_kvm_exports,EXPORT_SYMBOL_GPL))
-$(eval $(call check_kvm_exports,EXPORT_SYMBOL))
-
-undefine check_kvm_exports
-undefine get_kvm_exports
-undefine exports_grep_trailer
+kvm_exports_allowed := kvm_page_track_register_notifier \
+		       kvm_page_track_unregister_notifier \
+		       kvm_write_track_add_gfn \
+		       kvm_write_track_remove_gfn \
+		       kvm_file_to_kvm_fn
+
+$(eval $(call kvm_check_exports,EXPORT_SYMBOL_GPL))
+$(eval $(call kvm_check_exports,EXPORT_SYMBOL))
+
+undefine kvm_exports_allowed
 endif # CONFIG_KVM_X86
diff --git a/virt/kvm/Makefile.kvm b/virt/kvm/Makefile.kvm
index d047d4cf58c9..dd40544b8ecb 100644
--- a/virt/kvm/Makefile.kvm
+++ b/virt/kvm/Makefile.kvm
@@ -13,3 +13,36 @@ kvm-$(CONFIG_HAVE_KVM_IRQ_ROUTING) += $(KVM)/irqchip.o
 kvm-$(CONFIG_HAVE_KVM_DIRTY_RING) += $(KVM)/dirty_ring.o
 kvm-$(CONFIG_HAVE_KVM_PFNCACHE) += $(KVM)/pfncache.o
 kvm-$(CONFIG_KVM_GUEST_MEMFD) += $(KVM)/guest_memfd.o
+
+# Force grep to emit a goofy group separator that can in turn be replaced with
+# the above newline macro (newlines in Make are a nightmare).  Note, grep only
+# prints the group separator when N lines of context are requested via -C,
+# a.k.a. --NUM.  Simply request zero lines.  Print the separator only after
+# filtering out expected exports to avoid extra newlines in the error message.
+define __kvm_get_exports
+$(shell grep "$(1)" -C0 --include='*.[ch]' -nrw \
+	$(srctree)/virt/kvm $(srctree)/arch/$(SRCARCH)/kvm \
+	$(addprefix | grep -v -e ,$(kvm_exports_allowed)) \
+	| grep "$(1)" -C0 --group-separator="!SEP!")
+endef
+
+
+KVM_CHECK_EXPORT_DIRS ?= $(srctree)/virt/kvm $(srctree)/arch/$(ARCH)/kvm
+
+# Fail the build if any unwanted $(1) usage is found outside kvm_exports_allowed.
+define kvm_check_exports
+kvm_nr_exports := $(shell grep "$(1)" --include='*.[ch]' -nrw \
+	$(KVM_CHECK_EXPORT_DIRS) \
+	$(addprefix | grep -v -e ,$(kvm_exports_allowed)) | wc -l)
+
+ifneq (0,$$(kvm_nr_exports))
+$$(error ERROR ***\
+$$(newline)found $$(kvm_nr_exports) unwanted occurrences of $(1):\
+$$(newline)  $(subst !SEP!,$$(newline) ,$(call __kvm_get_exports,$(1)))\
+$$(newline)in directories:\
+$$(newline)  $(KVM_CHECK_EXPORT_DIRS)\
+$$(newline)If this is a valid exception add it to kvm_exports_allowed or\
+$$(newline)use EXPORT_SYMBOL_FOR_KVM_INTERNAL, not $(1))
+endif # kvm_nr_exports != 0
+undefine kvm_nr_exports
+endef # kvm_check_exports
-- 
2.53.0