Re: [PATCH bpf-next 2/6] libbpf: Add BTF_KIND_FLOAT support

[Ilya Leoshkevich <iii@linux.ibm.com>]

On Wed, 2021-02-17 at 23:16 -0800, Yonghong Song wrote:
> On 2/15/21 5:12 PM, Ilya Leoshkevich wrote:
> > The logic follows that of BTF_KIND_INT most of the time.
> > Sanitization
> > replaces BTF_KIND_FLOATs with equally-sized BTF_KIND_INTs on older
> > kernels.
> > 
> > Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
> > ---
> >   tools/lib/bpf/btf.c             | 44
> > +++++++++++++++++++++++++++++++++
> >   tools/lib/bpf/btf.h             |  8 ++++++
> >   tools/lib/bpf/btf_dump.c        |  4 +++
> >   tools/lib/bpf/libbpf.c          | 29 +++++++++++++++++++++-
> >   tools/lib/bpf/libbpf.map        |  5 ++++
> >   tools/lib/bpf/libbpf_internal.h |  2 ++
> >   6 files changed, 91 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
> > index d9c10830d749..07a30e98c3de 100644
> > --- a/tools/lib/bpf/btf.c
> > +++ b/tools/lib/bpf/btf.c

[...]

> > @@ -2445,6 +2450,9 @@ static void bpf_object__sanitize_btf(struct
> > bpf_object *obj, struct btf *btf)
> >                 } else if (!has_func_global && btf_is_func(t)) {
> >                         /* replace BTF_FUNC_GLOBAL with
> > BTF_FUNC_STATIC */
> >                         t->info = BTF_INFO_ENC(BTF_KIND_FUNC, 0,
> > 0);
> > +               } else if (!has_float && btf_is_float(t)) {
> > +                       /* replace FLOAT with INT */
> > +                       t->info = BTF_INFO_ENC(BTF_KIND_FLOAT, 0,
> > 0);
> 
> You can replace float with a "pointer to void" type.

Wouldn't this cause problems with 32-bit floats on 64-bit machines?

[...]