On Wed, Jul 07, 2021 at 05:06:17PM -0700, Andrii Nakryiko wrote:
> On Wed, Jul 7, 2021 at 2:53 PM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> >
> > Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs,
> > specifically for all trampoline attach types.
> >
> > The trampoline's caller IP address is stored in (ctx - 8) address.
> > so there's no reason to actually call the helper, but rather fixup
> > the call instruction and return [ctx - 8] value directly (suggested
> > by Alexei).
> >
> > [fixed has_get_func_ip wrong return type]
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > ---
> > include/uapi/linux/bpf.h | 7 +++++
> > kernel/bpf/verifier.c | 53 ++++++++++++++++++++++++++++++++++
> > kernel/trace/bpf_trace.c | 15 ++++++++++
> > tools/include/uapi/linux/bpf.h | 7 +++++
> > 4 files changed, 82 insertions(+)
> >
>
> [...]
>
> > static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
> > int *insn_idx_p)
> > {
> > @@ -6225,6 +6256,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
> > if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
> > env->prog->call_get_stack = true;
> >
> > + if (func_id == BPF_FUNC_get_func_ip) {
> > + if (has_get_func_ip(env))
>
> from has_xxx name I'd expect it returns true/false, so this reads
> super confusing. check_get_func_ip would be a bit more consistent with
> other cases like this (still reads confusing to me, but that's ok)
ok, will change
jirka
>
> > + return -ENOTSUPP;
> > + env->prog->call_get_func_ip = true;
> > + }
> > +
> > if (changes_data)
> > clear_all_pkt_pointers(env);
> > return 0;
>
> [...]
>
