On Tue, Apr 25, 2023 at 11:10 AM Yonghong Song <yhs@xxxxxxxx> wrote:
>
>
>
> On 4/25/23 10:04 AM, Stanislav Fomichev wrote:
> > On Mon, Apr 24, 2023 at 6:56 PM Yonghong Song <yhs@xxxxxxxx> wrote:
> >>
> >>
> >>
> >> On 4/24/23 5:01 PM, Stanislav Fomichev wrote:
> >>> From: Peng Wei <pengweiprc@xxxxxxxxxx>
> >>>
> >>> Compiling C++ BPF programs with existing bpf_helper_defs.h is not
>
> Just curious, why you want to compile BPF programs with C++?
> The patch looks good to me. But it would be great to know
> some reasoning since a lot of stuff, e.g., some CORE related
> intrinsics, not available for C++.
Can you share more? What's not available? Any pointers to the docs maybe?
People here want to try to use c++ to see if templating helps with v4
vs v6 handling.
We have a bunch of copy-paste around this place and would like to see
whether c++ could make it a bit more readable.
> >>> possible due to stricter C++ type conversions. C++ complains
> >>> about (void *) type conversions:
> >>>
> >>> bpf_helper_defs.h:57:67: error: invalid conversion from ‘void*’ to ‘void* (*)(void*, const void*)’ [-fpermissive]
> >>> 57 | static void *(*bpf_map_lookup_elem)(void *map, const void *key) = (void *) 1;
> >>> | ^~~~~~~~~~
> >>> | |
> >>> | void*
> >>>
> >>> Extend bpf_doc.py to use proper function type instead of void.
> >>
> >> Could you specify what exactly the compilation command triggering the
> >> above error?
> >
> > The following does it for me:
> > clang++ --include linux/types.h ./tools/lib/bpf/bpf_helper_defs.h
>
> Thanks. It would be good if you add the above compilation command
> in the commit message.
Sure, will add.
> >
> >
> >>>
> >>> Before:
> >>> static void *(*bpf_map_lookup_elem)(void *map, const void *key) = (void *) 1;
> >>>
> >>> After:
> >>> static void *(*bpf_map_lookup_elem)(void *map, const void *key) = (void *(*)(void *map, const void *key)) 1;
> >>>
> >>> Signed-off-by: Peng Wei <pengweiprc@xxxxxxxxxx>
> >>> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> >>> ---
> >>> scripts/bpf_doc.py | 7 ++++++-
> >>> 1 file changed, 6 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py
> >>> index eaae2ce78381..fa21137a90e7 100755
> >>> --- a/scripts/bpf_doc.py
> >>> +++ b/scripts/bpf_doc.py
> >>> @@ -827,6 +827,9 @@ COMMANDS
> >>> print(' *{}{}'.format(' \t' if line else '', line))
> >>>
> >>> print(' */')
> >>> + fptr_type = '%s%s(*)(' % (
> >>> + self.map_type(proto['ret_type']),
> >>> + ((' ' + proto['ret_star']) if proto['ret_star'] else ''))
> >>> print('static %s %s(*%s)(' % (self.map_type(proto['ret_type']),
> >>> proto['ret_star'], proto['name']), end='')
> >>> comma = ''
> >>> @@ -845,8 +848,10 @@ COMMANDS
> >>> one_arg += '{}'.format(n)
> >>> comma = ', '
> >>> print(one_arg, end='')
> >>> + fptr_type += one_arg
> >>>
> >>> - print(') = (void *) %d;' % helper.enum_val)
> >>> + fptr_type += ')'
> >>> + print(') = (%s) %d;' % (fptr_type, helper.enum_val))
> >>> print('')
> >>>
> >>> ###############################################################################
