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| author | Masahiro Yamada <masahiroy@kernel.org> | 2020-04-29 06:45:13 +0300 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2020-05-17 12:52:01 +0300 |
| commit | 9371f86ecb60f6f1f120e3d93fe892bbb70d04c0 (patch) | |
| tree | 3bf829d594785687c136b1d8295197f58b2038ef /net/bpfilter | |
| parent | 59721d4eb7f66f27440ad74f875b97e64133ee3b (diff) | |
| download | linux-9371f86ecb60f6f1f120e3d93fe892bbb70d04c0.tar.xz | |
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>
Diffstat (limited to 'net/bpfilter')
| -rw-r--r-- | net/bpfilter/Makefile | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile index 36580301da70..f6209e4827b9 100644 --- a/net/bpfilter/Makefile +++ b/net/bpfilter/Makefile @@ -5,14 +5,15 @@ hostprogs := bpfilter_umh bpfilter_umh-objs := main.o -KBUILD_HOSTCFLAGS += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi +KBUILD_HOSTCFLAGS += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \ + $(filter -m32 -m64, $(KBUILD_CFLAGS)) HOSTCC := $(CC) ifeq ($(CONFIG_BPFILTER_UMH), y) # builtin bpfilter_umh should be compiled with -static # since rootfs isn't mounted at the time of __init # function is called and do_execv won't find elf interpreter -KBUILD_HOSTLDFLAGS += -static +KBUILD_HOSTLDFLAGS += -static $(filter -m32 -m64, $(KBUILD_CFLAGS)) endif $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh |