On 7/6/22 10:28 AM, James Hilliard 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 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
It does look like that gcc kernel_helper attribute is better than '(void *) 1' style. The original clang uses '(void *) 1' style is just for simplicity. Do you mind to help implement similar attribute in clang so we don't need "#if" here?
#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(-)
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