On Tue, Aug 27, 2024 at 2:01 PM Alexei Starovoitov
<alexei.starovoitov@xxxxxxxxx> wrote:
>
> On Mon, Aug 26, 2024 at 3:48 PM JP Kobryn <inwardvessel@xxxxxxxxx> wrote:
> >
> > The additional hooks (and prog-to-hook mapping) for tracepoint and perf
> > event programs allow for registering kfuncs to be used within these
> > program types.
> >
> > Signed-off-by: JP Kobryn <inwardvessel@xxxxxxxxx>
> > ---
> > kernel/bpf/btf.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> > index 520f49f422fe..4816e309314e 100644
> > --- a/kernel/bpf/btf.c
> > +++ b/kernel/bpf/btf.c
> > @@ -210,6 +210,7 @@ enum btf_kfunc_hook {
> > BTF_KFUNC_HOOK_TC,
> > BTF_KFUNC_HOOK_STRUCT_OPS,
> > BTF_KFUNC_HOOK_TRACING,
> > + BTF_KFUNC_HOOK_TRACEPOINT,
> > BTF_KFUNC_HOOK_SYSCALL,
> > BTF_KFUNC_HOOK_FMODRET,
> > BTF_KFUNC_HOOK_CGROUP_SKB,
> > @@ -219,6 +220,7 @@ enum btf_kfunc_hook {
> > BTF_KFUNC_HOOK_LWT,
> > BTF_KFUNC_HOOK_NETFILTER,
> > BTF_KFUNC_HOOK_KPROBE,
> > + BTF_KFUNC_HOOK_PERF_EVENT,
> > BTF_KFUNC_HOOK_MAX,
> > };
> >
> > @@ -8306,6 +8308,8 @@ static int bpf_prog_type_to_kfunc_hook(enum bpf_prog_type prog_type)
> > case BPF_PROG_TYPE_TRACING:
> > case BPF_PROG_TYPE_LSM:
> > return BTF_KFUNC_HOOK_TRACING;
> > + case BPF_PROG_TYPE_TRACEPOINT:
> > + return BTF_KFUNC_HOOK_TRACEPOINT;
>
> why special case tp and perf_event and only limit them to cpumask?
> The following would be equally safe, no?
Assuming we don't have kfuncs that accepts program context (like
bpf_get_stack(), if it was a kfunc) and that doesn't access
bpf_run_ctx (like bpf_get_func_ip()). We just need to be careful about
adding new special kfuncs like that going forward (not sure how to
best ensure we don't forget, though). Other than that I agree that
it's all "tracing".
> case BPF_PROG_TYPE_TRACING:
> case BPF_PROG_TYPE_LSM:
> + case BPF_PROG_TYPE_TRACEPOINT:
> + case BPF_PROG_TYPE_PERF_EVENT:
> return BTF_KFUNC_HOOK_TRACING;
> ?
