On Wed, Jul 01, 2020 at 06:26:44PM +0900, Masahiro Yamada wrote:
> Originally, bpfilter_umh was linked with -static only when
> CONFIG_BPFILTER_UMH=y.
>
> Commit 8a2cc0505cc4 ("bpfilter: use 'userprogs' syntax to build
> bpfilter_umh") silently, accidentally dropped the CONFIG_BPFILTER_UMH=y
> test in the Makefile. Revive it in order to link it dynamically when
> CONFIG_BPFILTER_UMH=m.
>
> Since commit b1183b6dca3e ("bpfilter: check if $(CC) can link static
> libc in Kconfig"), the compiler must be capable of static linking to
> enable CONFIG_BPFILTER_UMH, but it requires more than needed.
>
> To loosen the compiler requirement, I changed the dependency as follows:
>
> depends on CC_CAN_LINK
> depends on m || CC_CAN_LINK_STATIC
>
> If CONFIG_CC_CAN_LINK_STATIC in unset, CONFIG_BPFILTER_UMH is restricted
> to 'm' or 'n'.
>
> In theory, CONFIG_CC_CAN_LINK is not required for CONFIG_BPFILTER_UMH=y,
> but I did not come up with a good way to describe it.
>
> Fixes: 8a2cc0505cc4 ("bpfilter: use 'userprogs' syntax to build bpfilter_umh")
> Reported-by: Michal Kubecek <[email protected]>
> Signed-off-by: Masahiro Yamada <[email protected]>Tested-by: Michal Kubecek <[email protected]> Thank you, Michal > --- > > net/bpfilter/Kconfig | 10 ++++++---- > net/bpfilter/Makefile | 2 ++ > 2 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/net/bpfilter/Kconfig b/net/bpfilter/Kconfig > index 84015ef3ee27..73d0b12789f1 100644 > --- a/net/bpfilter/Kconfig > +++ b/net/bpfilter/Kconfig > @@ -9,12 +9,14 @@ menuconfig BPFILTER > if BPFILTER > config BPFILTER_UMH > tristate "bpfilter kernel module with user mode helper" > - depends on CC_CAN_LINK_STATIC > + depends on CC_CAN_LINK > + depends on m || CC_CAN_LINK_STATIC > default m > help > This builds bpfilter kernel module with embedded user mode helper > > - Note: your toolchain must support building static binaries, since > - rootfs isn't mounted at the time when __init functions are called > - and do_execv won't be able to find the elf interpreter. > + Note: To compile this as built-in, your toolchain must support > + building static binaries, since rootfs isn't mounted at the time > + when __init functions are called and do_execv won't be able to find > + the elf interpreter. > endif > diff --git a/net/bpfilter/Makefile b/net/bpfilter/Makefile > index f23b53294fba..cdac82b8c53a 100644 > --- a/net/bpfilter/Makefile > +++ b/net/bpfilter/Makefile > @@ -7,10 +7,12 @@ userprogs := bpfilter_umh > bpfilter_umh-objs := main.o > userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi > > +ifeq ($(CONFIG_BPFILTER_UMH), y) > # builtin bpfilter_umh should be linked with -static > # since rootfs isn't mounted at the time of __init > # function is called and do_execv won't find elf interpreter > userldflags += -static > +endif > > $(obj)/bpfilter_umh_blob.o: $(obj)/bpfilter_umh > > -- > 2.25.1 >
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