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Masahiro Yamada 9371f86ecb bpfilter: match bit size of bpfilter_umh to that of the kernel

bpfilter_umh is built for the default machine bit of the compiler,
which may not match to the bit size of the kernel.

This happens in the scenario below:

You can use biarch GCC that defaults to 64-bit for building the 32-bit
kernel. In this case, Kbuild passes -m32 to teach the compiler to
produce 32-bit kernel space objects. However, it is missing when
building bpfilter_umh. It is built as a 64-bit ELF, and then embedded
into the 32-bit kernel.

The 32-bit kernel and 64-bit umh is a bad combination.

In theory, we can have 32-bit umh running on 64-bit kernel, but we do
not have a good reason to support such a usecase.

The best is to match the bit size between them.

Pass -m32 or -m64 to the umh build command if it is found in
$(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

2020-05-17 18:52:01 +09:00

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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/elfcore.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/nfc.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)/*)))

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