| Message ID | 20200701092644.762234-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | bpfilter: allow to build bpfilter_umh as a module without static library | expand |
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 <mkubecek@suse.cz> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Tested-by: Michal Kubecek <mkubecek@suse.cz> 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 >
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 <mkubecek@suse.cz> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> lgtm Do you mind I'll take it into bpf-next tree? Eric is working on a bunch of patches in this area. I'll take his set into bpf-next as well and then can apply this patch. Just to make sure there are no conflicts.
On Thu, Jul 2, 2020 at 2:46 AM Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote: > > 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 <mkubecek@suse.cz> > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > > lgtm > Do you mind I'll take it into bpf-next tree? > Eric is working on a bunch of patches in this area. I'll take his set > into bpf-next as well and then can apply this patch. > Just to make sure there are no conflicts. Please go ahead. Thank you.
On Wed, Jul 1, 2020 at 10:50 AM Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Thu, Jul 2, 2020 at 2:46 AM Alexei Starovoitov > <alexei.starovoitov@gmail.com> wrote: > > > > 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 <mkubecek@suse.cz> > > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > > > > lgtm > > Do you mind I'll take it into bpf-next tree? > > Eric is working on a bunch of patches in this area. I'll take his set > > into bpf-next as well and then can apply this patch. > > Just to make sure there are no conflicts. > > Please go ahead. I've merged Eric's set and applied yours on top. Thanks
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
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 <mkubecek@suse.cz> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> --- net/bpfilter/Kconfig | 10 ++++++---- net/bpfilter/Makefile | 2 ++ 2 files changed, 8 insertions(+), 4 deletions(-)