On Fri, Sep 02, 2022 at 07:20:40PM +0200, Peter Zijlstra wrote: > On Fri, Sep 02, 2022 at 06:53:38PM +0200, Jiri Olsa wrote: > > > Are you sure you want the notrace x86_64 only? > > > > > > That is, perhaps something like this... > > > > > > +#ifdef CONFIG_X86_64 > > > +#define BPF_DISPATCHER_ATTRIBUTES __attribute__((patchable_function_entry(5))) > > > +#else > > > +#define BPF_DISPATCHER_ATTRIBUTES > > > +#endif > > > + > > > #define DEFINE_BPF_DISPATCHER(name) \ > > > + notrace BPF_DISPATCHER_ATTRIBUTES \ > > > noinline __nocfi unsigned int bpf_dispatcher_##name##_func( \ > > > > > > > that's also an option.. but I don't this it's big deal that the function > > is traceable on other arches, because the dispatcher image is generated > > only on x86, so no other arch is touching that function entry, so it's > > safe for ftrace to attach > > It just seems like a pointless difference. ok, I'll use notrace as default > > From a code-gen POV you don't strictly need the notrace; without it > it'll generate: > > bpf_dispatcher_name_func: > nop > nop > nop > nop > nop > call __fentry__ > RET > > It'll just function 'weird', but it'll 'work'. I'll use notrace for all archs as you suggests, so there's less surprise in future if some other arch implements dispatcher image thanks, jirka
