> On Thu, Nov 09, 2023 at 03:49:49PM +0000, Qing Zhao wrote: >> Is it reasonable to add one option to disable the “counted_by” attribute? >> (then no insertion of the new .ACCESS_WITH_SIZE into IL). >> >> The major reason is: some users might want to ignore all the “counted_by” >> attribute added in the source code, >> We need to provide them a way to disable this feature. > > -D'counted_by(x)=' > and/or > -D'__counted_by__(x)=' > ?
The insertion of .ACCESS_WITH_SIZE collides with the BPF CO-RE preserve_access_index implementation. I don't think this will be a problem in practice (the BPF program can define counted_by to the empty string as Jakub suggests) but we ought to at least detect when a data structure featuring a counted_by FMA is accessed with access index preservation (either attribute or builtin) and either error out or warning out and try to accomodate by turning the .ACCESS_WTIH_INDEX back to plain accesses. We can do either with BPF specific backend code.
