On Mon, Mar 25, 2024 at 11:53:36AM -0600, Daniel Xu wrote: > This patchset teaches pahole to parse symbols in .BTF_ids section in > vmlinux and discover exported kfuncs. Pahole then takes the list of > kfuncs and injects a BTF_KIND_DECL_TAG for each kfunc. > > Example of encoding: > > $ bpftool btf dump file .tmp_vmlinux.btf | rg "DECL_TAG 'bpf_kfunc'" | wc -l > 121 > > $ bpftool btf dump file .tmp_vmlinux.btf | rg 56337 > [56337] FUNC 'bpf_ct_change_timeout' type_id=56336 linkage=static > [127861] DECL_TAG 'bpf_kfunc' type_id=56337 component_idx=-1 > > This enables downstream users and tools to dynamically discover which > kfuncs are available on a system by parsing vmlinux or module BTF, both > available in /sys/kernel/btf. > > This feature is enabled with --btf_features=decl_tag,decl_tag_kfuncs. > > === Changelog === I'm a bit lagged on my backlog, will try and process these soon, - Arnaldo > Changes from v5: > * Add gobuffer__sort() helper > * Use strstarts() instead of strncmp() > * Use uint64_t instead of size_t > * Add clarifying comments for get_func_name() > > Changes from v4: > * Update man page with decl_tag_kfuncs feature > * Fix release mode build warnings > * Add elf_getshrstrndx() error checking > * Disable tagging if decl_tag feature is off > * Fix malformed func name handling > > Changes from v3: > * Guard kfunc tagging behind feature flag > * Use struct btf_id_set8 definition > * Remove unnecessary member from btf_encoder > * Fix code styling > > Changes from v2: > * More reliably detect kfunc membership in set8 by tracking set addr ranges > * Rename some variables/functions to be more clear about kfunc vs func > > Changes from v1: > * Fix resource leaks > * Fix callee -> caller typo > * Rename btf_decl_tag from kfunc -> bpf_kfunc > * Only grab btf_id_set funcs tagged kfunc > * Presort btf func list > > Daniel Xu (3): > gobuffer: Add gobuffer__sort() helper > pahole: Add --btf_feature=decl_tag_kfuncs feature > pahole: Inject kfunc decl tags into BTF > > btf_encoder.c | 374 +++++++++++++++++++++++++++++++++++++++++++++ > dwarves.h | 1 + > gobuffer.c | 5 + > gobuffer.h | 2 + > man-pages/pahole.1 | 1 + > pahole.c | 1 + > 6 files changed, 384 insertions(+) > > -- > 2.44.0
