2 files changed, 113 insertions, 0 deletions
diff --git a/usr/include/.gitignore b/usr/include/.gitignore
new file mode 100644
index 000000000..d2fab782c
--- /dev/null
+++ b/usr/include/.gitignore
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+*
+!.gitignore
+!Makefile
diff --git a/usr/include/Makefile b/usr/include/Makefile
new file mode 100644
index 000000000..703a255cd
--- /dev/null
+++ b/usr/include/Makefile
@@ -0,0 +1,109 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+# Unlike the kernel space, exported headers are written in standard C.
+#  - Forbid C++ style comments
+#  - Use '__inline__', '__asm__' instead of 'inline', 'asm'
+#
+# -std=c90 (equivalent to -ansi) catches the violation of those.
+# We cannot go as far as adding -Wpedantic since it emits too many warnings.
+UAPI_CFLAGS := -std=c90 -Wall -Werror=implicit-function-declaration
+
+# In theory, we do not care -m32 or -m64 for header compile tests.
+# It is here just because CONFIG_CC_CAN_LINK is tested with -m32 or -m64.
+UAPI_CFLAGS += $(filter -m32 -m64, $(KBUILD_CFLAGS))
+
+override c_flags = $(UAPI_CFLAGS) -Wp,-MMD,$(depfile) -I$(objtree)/usr/include
+
+# The following are excluded for now because they fail to build.
+#
+# Do not add a new header to the blacklist without legitimate reason.
+# Please consider to fix the header first.
+#
+# Sorted alphabetically.
+no-header-test += asm/shmbuf.h
+no-header-test += asm/signal.h
+no-header-test += asm/ucontext.h
+no-header-test += drm/vmwgfx_drm.h
+no-header-test += linux/am437x-vpfe.h
+no-header-test += linux/android/binder.h
+no-header-test += linux/android/binderfs.h
+no-header-test += linux/coda.h
+no-header-test += linux/errqueue.h
+no-header-test += linux/fsmap.h
+no-header-test += linux/hdlc/ioctl.h
+no-header-test += linux/ivtv.h
+no-header-test += linux/kexec.h
+no-header-test += linux/matroxfb.h
+no-header-test += linux/omap3isp.h
+no-header-test += linux/omapfb.h
+no-header-test += linux/patchkey.h
+no-header-test += linux/phonet.h
+no-header-test += linux/reiserfs_xattr.h
+no-header-test += linux/sctp.h
+no-header-test += linux/signal.h
+no-header-test += linux/sysctl.h
+no-header-test += linux/usb/audio.h
+no-header-test += linux/v4l2-mediabus.h
+no-header-test += linux/v4l2-subdev.h
+no-header-test += linux/videodev2.h
+no-header-test += linux/vm_sockets.h
+no-header-test += sound/asequencer.h
+no-header-test += sound/asoc.h
+no-header-test += sound/asound.h
+no-header-test += sound/compress_offload.h
+no-header-test += sound/emu10k1.h
+no-header-test += sound/sfnt_info.h
+no-header-test += xen/evtchn.h
+no-header-test += xen/gntdev.h
+no-header-test += xen/privcmd.h
+
+# More headers are broken in some architectures
+
+ifeq ($(SRCARCH),arc)
+no-header-test += linux/bpf_perf_event.h
+endif
+
+ifeq ($(SRCARCH),ia64)
+no-header-test += asm/setup.h
+no-header-test += asm/sigcontext.h
+no-header-test += asm/perfmon.h
+no-header-test += asm/perfmon_default_smpl.h
+no-header-test += linux/if_bonding.h
+endif
+
+ifeq ($(SRCARCH),mips)
+no-header-test += asm/stat.h
+endif
+
+ifeq ($(SRCARCH),powerpc)
+no-header-test += asm/stat.h
+no-header-test += linux/bpf_perf_event.h
+endif
+
+ifeq ($(SRCARCH),riscv)
+no-header-test += linux/bpf_perf_event.h
+endif
+
+ifeq ($(SRCARCH),sparc)
+no-header-test += asm/stat.h
+no-header-test += asm/uctx.h
+no-header-test += asm/fbio.h
+endif
+
+# asm-generic/*.h is used by asm/*.h, and should not be included directly
+no-header-test += asm-generic/%
+
+extra-y := $(patsubst $(obj)/%.h,%.hdrtest, $(shell find $(obj) -name '*.h' 2>/dev/null))
+
+# Include the header twice to detect missing include guard.
+quiet_cmd_hdrtest = HDRTEST $<
+      cmd_hdrtest = \
+		$(CC) $(c_flags) -S -o /dev/null -x c /dev/null \
+			$(if $(filter-out $(no-header-test), $*.h), -include $< -include $<); \
+		$(PERL) $(srctree)/scripts/headers_check.pl $(obj) $(SRCARCH) $<; \
+		touch $@
+
+$(obj)/%.hdrtest: $(obj)/%.h FORCE
+	$(call if_changed_dep,hdrtest)
+
+clean-files += $(filter-out Makefile, $(notdir $(wildcard $(obj)/*)))