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Miller" , David Ahern , Dave Hansen , X86 ML , Steven Rostedt , Mathieu Desnoyers , Quentin Monnet , bpf , linux-arm-kernel , LKML , linux-riscv , linux-s390 , Network Development , linux-trace-kernel@vger.kernel.org, "open list:KERNEL SELFTEST FRAMEWORK" , linux-stm32@st-md-mailman.stormreply.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Mar 12, 2024 at 9:51=E2=80=AFAM Alexei Starovoitov wrote: > > On Mon, Mar 11, 2024 at 2:35=E2=80=AFAM Menglong Dong > wrote: > > > > Add target btf to the function args of bpf_check_attach_target(), then > > the caller can specify the btf to check. > > > > Signed-off-by: Menglong Dong > > --- > > include/linux/bpf_verifier.h | 1 + > > kernel/bpf/syscall.c | 6 ++++-- > > kernel/bpf/trampoline.c | 1 + > > kernel/bpf/verifier.c | 8 +++++--- > > 4 files changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.= h > > index 4b0f6600e499..6cb20efcfac3 100644 > > --- a/include/linux/bpf_verifier.h > > +++ b/include/linux/bpf_verifier.h > > @@ -811,6 +811,7 @@ static inline void bpf_trampoline_unpack_key(u64 ke= y, u32 *obj_id, u32 *btf_id) > > int bpf_check_attach_target(struct bpf_verifier_log *log, > > const struct bpf_prog *prog, > > const struct bpf_prog *tgt_prog, > > + struct btf *btf, > > u32 btf_id, > > struct bpf_attach_target_info *tgt_info); > > void bpf_free_kfunc_btf_tab(struct bpf_kfunc_btf_tab *tab); > > diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c > > index d1cd645ef9ac..6128c3131141 100644 > > --- a/kernel/bpf/syscall.c > > +++ b/kernel/bpf/syscall.c > > @@ -3401,9 +3401,11 @@ static int bpf_tracing_prog_attach(struct bpf_pr= og *prog, > > * need a new trampoline and a check for compatibility > > */ > > struct bpf_attach_target_info tgt_info =3D {}; > > + struct btf *btf; > > > > - err =3D bpf_check_attach_target(NULL, prog, tgt_prog, b= tf_id, > > - &tgt_info); > > + btf =3D tgt_prog ? tgt_prog->aux->btf : prog->aux->atta= ch_btf; > > I think it's better to keep this bit inside bpf_check_attach_target(), > since a lot of other code in there is working with if (tgt_prog) ... > so if the caller messes up passing tgt_prog->aux->btf with tgt_prog > the bug will be difficult to debug. In the previous version, I pass the attach_btf with the following way: + origin_btf =3D prog->aux->attach_btf; + /* use the new attach_btf to check the target */ + prog->aux->attach_btf =3D attach_btf; err =3D bpf_check_attach_target(NULL, prog, tgt_prog, btf_id, &tgt_info); + prog->aux->attach_btf =3D origin_btf; And Jiri suggested to add the attach_btf to the function args of bpf_check_attach_target(). Ennn....Should I convert to the old way? Thanks! Menglong Dong > > > + err =3D bpf_check_attach_target(NULL, prog, tgt_prog, b= tf, > > + btf_id, &tgt_info);