On Fri, Dec 8, 2023 at 12:18 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Fri, Dec 08, 2023 at 11:32:07AM -0800, Alexei Starovoitov wrote: > > On Fri, Dec 8, 2023 at 5:41 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > > > On Fri, Dec 08, 2023 at 11:29:40AM +0100, Peter Zijlstra wrote: > > > > The only problem I now have is the one XXX, I'm not entirely sure what > > > > signature to use there. > > > > > > > @@ -119,6 +119,7 @@ int bpf_struct_ops_test_run(struct bpf_p > > > > op_idx = prog->expected_attach_type; > > > > err = bpf_struct_ops_prepare_trampoline(tlinks, link, > > > > &st_ops->func_models[op_idx], > > > > + /* XXX */ NULL, > > > > image, image + PAGE_SIZE); > > > > if (err < 0) > > > > goto out; > > > > > > Duh, that should ofcourse be something of dummy_ops_test_ret_fn type. > > > Let me go fix that. > > > > Right. That should work. > > A bit wasteful to generate real code just to read hash from it > > via cfi_get_func_hash(), but it's a neat idea. > > Right, bit wasteful. But the advantage is that I get a structure with > pointers that exactly mirrors the structure we're writing. > > > I guess it's hard to get kcfi from __ADDRESSABLE in plain C > > and sprinkling asm("cfi_xxx: .long __kcfi_typeid..."); is worse? > > Even if it's a macro ? > > I can try this, but I'm not sure it'll be pretty. Even if I wrap it in a > decent macro, I still get to define a ton of variables and then wrap the > lot into a structure -- one that expects function pointers. > > I'll see how horrible it will become. I mean we don't need to store a pointer to a func in stubs. Can it be, roughly: extern void bpf_tcp_ca_cong_avoid(struct sock *sk, u32 ack, u32 acked); KCFI_MACRO(hash_of_cong_avoid, bpf_tcp_ca_cong_avoid); u32 __array_of_kcfi_hash[] = {hash_of_cong_avoid, hash_of_set_state,...}; .bpf_ops_stubs = __array_of_kcfi_hash,