On Mon, 19 Jul 2021, Andrii Nakryiko wrote: > On Mon, Jul 19, 2021 at 2:41 PM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote: > > > > __int128 is not supported for some 32-bit platforms (arm and i386). > > __int128 was used in carrying out computations on bitfields which > > aid display, but the same calculations could be done with __u64 > > with the small effect of not supporting 128-bit bitfields. > > > > With these changes, a big-endian issue with casting 128-bit integers > > to 64-bit for enum bitfields is solved also, as we now use 64-bit > > integers for bitfield calculations. > > > > Reported-by: Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> > > Reported-by: Linux Kernel Functional Testing <lkft@xxxxxxxxxx> > > Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx> > > --- > > Changes look good to me, thanks. But they didn't appear in patchworks > yet so I can't easily test and apply them. It might be because of > patchworks delay or due to a very long CC list. Try trimming the cc > list down and re-submit? > Done, looks like the v2 with the trimmed cc list made it into patchwork this time. > Also, while I agree that supporting 128-bit bitfields isn't important, > I wonder if we should warn/error on that (instead of shifting by > negative amount and reporting some garbage value), what do you think? > Is there one place in the code where we can error out early if the > type actually has bitfield with > 64 bits? I'd prefer to keep > btf_dump_bitfield_get_data() itself non-failing though. > Sorry, I missed the last part and made that function fail since it's probably the easiest place to capture too-large bitfields. I renamed it to btf_dump_get_bitfield_value() to match btf_dump_get_enum_value() which as a similar function signature (return int, pass in a pointer to the value we want to retrieve). We can't localize bitfield size checking to btf_dump_type_data_check_zero() because - depending on flags - the associated checks might not be carried out. So duplication of bitfield size checks between the zero checking and bitfield/enum bitfield display seems inevitable, and that being the case, the extra error checking required around btf_dump_get_bitfield_value() seems to be required. I might be missing a better approach here of course; let me know what you think. Thanks again! Alan
