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 adds conditional blocks for GCC while leaving clang codepaths
unchanged, for example:
#if __GNUC__ && !__clang__
void *bpf_map_lookup_elem(void *map, const void *key) __attribute__((kernel_helper(1)));
#else
static void *(*bpf_map_lookup_elem)(void *map, const void *key) = (void *) 1;
#endif
[...]
#if __GNUC__ && !__clang__
long bpf_map_update_elem(void *map, const void *key, const void *value, __u64 flags) __attribute__((kernel_helper(2)));
#else
static long (*bpf_map_update_elem)(void *map, const void *key, const void *value, __u64 flags) = (void *) 2;
#endif
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 v1 -> v2:
- more details in commit log
---
scripts/bpf_doc.py | 43 ++++++++++++++++++++++++++-----------------
1 file changed, 26 insertions(+), 17 deletions(-)