On Tue, Jul 12, 2022 at 4:26 PM James Hilliard <james.hilliard1@xxxxxxxxx> wrote: > > The current bpf_helper_defs.h helpers are llvm specific and don't work > correctly with gcc. > > GCC appears to required kernel helper funcs to have the following > attribute set: __attribute__((kernel_helper(NUM))) > > Generate gcc compatible headers based on the format in bpf-helpers.h. > > This generates GCC/Clang compatible helpers, for example: > /* Helper macro for GCC/Clang compatibility */ > #define NOARG > #if __GNUC__ && !__clang__ > #define BPF_HELPER_DEF(num, ret_star, ret_type, name, ...) \ > ret_type ret_star name(__VA_ARGS__) __attribute__((kernel_helper(num))); > #else > #define BPF_HELPER_DEF(num, ret_star, ret_type, name, ...) \ > static ret_type ret_star(*name)(__VA_ARGS__) = (void *) num; > #endif > > BPF_HELPER_DEF(1, *, void, bpf_map_lookup_elem, void *map, const void *key) > > BPF_HELPER_DEF(2, NOARG, long, bpf_map_update_elem, void *map, const void *key, const void *value, __u64 flags) > > See: > https://github.com/gcc-mirror/gcc/blob/releases/gcc-12.1.0/gcc/config/bpf/bpf-helpers.h#L24-L27 > > This fixes the following build error: > error: indirect call in function, which are not supported by eBPF > > Signed-off-by: James Hilliard <james.hilliard1@xxxxxxxxx> > --- > Changes v2 -> v3: > - use a conditional helper macro > Changes v1 -> v2: > - more details in commit log > --- > scripts/bpf_doc.py | 21 ++++++++++++++++++--- > 1 file changed, 18 insertions(+), 3 deletions(-) > > diff --git a/scripts/bpf_doc.py b/scripts/bpf_doc.py > index a0ec321469bd..45f51ff1318c 100755 > --- a/scripts/bpf_doc.py > +++ b/scripts/bpf_doc.py > @@ -717,6 +717,16 @@ class PrinterHelpers(Printer): > header = '''\ > /* This is auto-generated file. See bpf_doc.py for details. */ > > +/* Helper macro for GCC/Clang compatibility */ > +#define NOARG > +#if __GNUC__ && !__clang__ > +#define BPF_HELPER_DEF(num, ret_star, ret_type, name, ...) \\ > +ret_type ret_star name(__VA_ARGS__) __attribute__((kernel_helper(num))); > +#else > +#define BPF_HELPER_DEF(num, ret_star, ret_type, name, ...) \\ > +static ret_type ret_star(*name)(__VA_ARGS__) = (void *) num; > +#endif Nack for the reasons stated earlier.
