On Wed, Sep 22, 2021 at 03:48:55AM IST, Andrii Nakryiko wrote: > On Mon, Sep 20, 2021 at 7:15 AM Kumar Kartikeya Dwivedi > <memxor@xxxxxxxxx> wrote: > > > > This commit moves BTF ID lookup into the newly added registration > > helper, in a way that the bbr, cubic, and dctcp implementation set up > > their sets in the bpf_tcp_ca kfunc_btf_set list, while the ones not > > dependent on modules are looked up from the wrapper function. > > > > This lifts the restriction for them to be compiled as built in objects, > > and can be loaded as modules if required. Also modify Makefile.modfinal > > to resolve_btfids in TCP congestion control modules if the config option > > is set, using the base BTF support added in the previous commit. > > > > See following commits for background on use of: > > > > CONFIG_X86 ifdef: > > 569c484f9995 (bpf: Limit static tcp-cc functions in the .BTF_ids list to x86) > > > > CONFIG_DYNAMIC_FTRACE ifdef: > > 7aae231ac93b (bpf: tcp: Limit calling some tcp cc functions to CONFIG_DYNAMIC_FTRACE) > > > > [ resolve_btfids uses --no-fail because some crypto kernel modules > > under arch/x86/crypto generated from ASM do not have the .BTF sections ] > > > > Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx> > > --- > > include/linux/btf.h | 4 ++++ > > kernel/bpf/btf.c | 3 +++ > > net/ipv4/bpf_tcp_ca.c | 34 +++------------------------------- > > net/ipv4/tcp_bbr.c | 28 +++++++++++++++++++++++++++- > > net/ipv4/tcp_cubic.c | 26 +++++++++++++++++++++++++- > > net/ipv4/tcp_dctcp.c | 26 +++++++++++++++++++++++++- > > scripts/Makefile.modfinal | 1 + > > 7 files changed, 88 insertions(+), 34 deletions(-) > > > > [...] > > > diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal > > index ff805777431c..b4f83533eda6 100644 > > --- a/scripts/Makefile.modfinal > > +++ b/scripts/Makefile.modfinal > > @@ -41,6 +41,7 @@ quiet_cmd_btf_ko = BTF [M] $@ > > cmd_btf_ko = \ > > if [ -f vmlinux ]; then \ > > LLVM_OBJCOPY="$(OBJCOPY)" $(PAHOLE) -J --btf_base vmlinux $@; \ > > + $(RESOLVE_BTFIDS) --no-fail -s vmlinux $@; \ > > I think I've asked that before, but I don't remember this being > answered. Why is this --no-fail? > Sorry, the first time, I missed that mail, and then it was too late so I decided to put the reason in the commit message above. > > [ resolve_btfids uses --no-fail because some crypto kernel modules > > under arch/x86/crypto generated from ASM do not have the .BTF sections ] I could add a mode that fails only when processing a .BTF section present in object fails, would that be better? -- Kartikeya
