This patchset enables both detecting as well as dumping compilable prototypes for kfuncs.
The first commit instructs pahole to DECL_TAG kfuncs when available. This requires v1.27 which was released on 6/11/24. With it, users will be able to look at BTF inside vmlinux (or modules) and check if the kfunc they want is available.
The final commit teaches bpftool how to dump kfunc prototypes. This is done for developer convenience.
The rest of the commits are fixups to enable selftests to use the newly dumped kfunc prototypes. With these, selftests will regularly exercise the newly added codepaths.
Tested with and without the required pahole changes:
* https://github.com/kernel-patches/bpf/pull/7186 * https://github.com/kernel-patches/bpf/pull/7187
=== Changelog === From v4: * Change bpf_session_cookie() return type * Only fixup used fentry test kfunc prototypes * Extract out projection detection into shared btf_is_projection_of() * Fix kernel test robot build warnings about doc comments
From v3: * Teach selftests to use dumped prototypes
From v2: * Update Makefile.btf with pahole flag * More error checking * Output formatting changes * Drop already-merged commit
From v1: * Add __weak annotation * Use btf_dump for kfunc prototypes * Update kernel bpf_rdonly_cast() signature
Daniel Xu (12): kbuild: bpf: Tell pahole to DECL_TAG kfuncs bpf: selftests: Fix bpf_iter_task_vma_new() prototype bpf: selftests: Fix fentry test kfunc prototypes bpf: selftests: Fix bpf_cpumask_first_zero() kfunc prototype bpf: selftests: Fix bpf_map_sum_elem_count() kfunc prototype bpf: Make bpf_session_cookie() kfunc return long * bpf: selftests: Namespace struct_opt callbacks in bpf_dctcp bpf: verifier: Relax caller requirements for kfunc projection type args bpf: treewide: Align kfunc signatures to prog point-of-view bpf: selftests: nf: Opt out of using generated kfunc prototypes bpf: selftests: xfrm: Opt out of using generated kfunc prototypes bpftool: Support dumping kfunc prototypes from BTF
fs/verity/measure.c | 5 +- include/linux/bpf.h | 8 +-- include/linux/btf.h | 1 + kernel/bpf/btf.c | 13 ++++- kernel/bpf/crypto.c | 24 +++++--- kernel/bpf/helpers.c | 39 +++++++++---- kernel/bpf/verifier.c | 12 +++- kernel/trace/bpf_trace.c | 17 +++--- net/core/filter.c | 32 +++++++---- scripts/Makefile.btf | 2 +- tools/bpf/bpftool/btf.c | 55 +++++++++++++++++++ .../testing/selftests/bpf/bpf_experimental.h | 2 +- tools/testing/selftests/bpf/progs/bpf_dctcp.c | 36 ++++++------ .../selftests/bpf/progs/get_func_ip_test.c | 7 +-- .../selftests/bpf/progs/ip_check_defrag.c | 10 ++-- .../selftests/bpf/progs/map_percpu_stats.c | 2 +- .../selftests/bpf/progs/nested_trust_common.h | 2 +- .../testing/selftests/bpf/progs/test_bpf_nf.c | 1 + .../selftests/bpf/progs/test_bpf_nf_fail.c | 1 + .../bpf/progs/verifier_netfilter_ctx.c | 6 +- .../selftests/bpf/progs/xdp_synproxy_kern.c | 1 + tools/testing/selftests/bpf/progs/xfrm_info.c | 1 + 22 files changed, 193 insertions(+), 84 deletions(-)