Re: llvm bpf debug info. Re: [RFC PATCH v4 3/3] bpf: Introduce function for outputing data to perf event

[Alexei Starovoitov <ast@plumgrid.com>]

On 7/29/15 1:00 PM, pi3orama wrote:
> I was wondering if you could give us a hint on adding BPF specific builtins?
>
> Doesn't like other machines, currently there's no Builtins.def for BPF to hold
> builtins for that specific target. If we start creating such builtins, we can bring
> more there. One builtins I want to see should be __builtin_bpf_strcmp(char*, char*),
> with that we can filter events base on name of a task. What I really need is filtering
> events based on comm of the main thread, which should be useful on Android
> since in Android name of working threads are always something like "Binder_?",
> only the main threads names are meaningful. But let's work on strcmp first.

Currently there are 4 of them in IntrinsicsBPF.td
but I don't see how strcmp can work with current no-loops restriction.
As an alternative to filter binder threads you can use
memcmp(ptr, "Binder_", 6) since it will get unrolled fully.