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| author | Daniel Xu <dxu@dxuuu.xyz> | 2024-01-28 18:24:08 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-01-31 20:40:56 -0800 |
| commit | 6f3189f38a3e995232e028a4c341164c4aca1b20 (patch) | |
| tree | fd932c0339367596adb67fd652849506971fda3f /Documentation/bpf | |
| parent | a05e90427ef6706f59188b379ad6366b9d298bc5 (diff) | |
| download | lwn-6f3189f38a3e995232e028a4c341164c4aca1b20.tar.gz lwn-6f3189f38a3e995232e028a4c341164c4aca1b20.zip | |
bpf: treewide: Annotate BPF kfuncs in BTF
This commit marks kfuncs as such inside the .BTF_ids section. The upshot
of these annotations is that we'll be able to automatically generate
kfunc prototypes for downstream users. The process is as follows:
1. In source, use BTF_KFUNCS_START/END macro pair to mark kfuncs
2. During build, pahole injects into BTF a "bpf_kfunc" BTF_DECL_TAG for
each function inside BTF_KFUNCS sets
3. At runtime, vmlinux or module BTF is made available in sysfs
4. At runtime, bpftool (or similar) can look at provided BTF and
generate appropriate prototypes for functions with "bpf_kfunc" tag
To ensure future kfunc are similarly tagged, we now also return error
inside kfunc registration for untagged kfuncs. For vmlinux kfuncs,
we also WARN(), as initcall machinery does not handle errors.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Acked-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/e55150ceecbf0a5d961e608941165c0bee7bc943.1706491398.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'Documentation/bpf')
| -rw-r--r-- | Documentation/bpf/kfuncs.rst | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index 7985c6615f3c..a8f5782bd833 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -177,10 +177,10 @@ In addition to kfuncs' arguments, verifier may need more information about the type of kfunc(s) being registered with the BPF subsystem. To do so, we define flags on a set of kfuncs as follows:: - BTF_SET8_START(bpf_task_set) + BTF_KFUNCS_START(bpf_task_set) BTF_ID_FLAGS(func, bpf_get_task_pid, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_put_pid, KF_RELEASE) - BTF_SET8_END(bpf_task_set) + BTF_KFUNCS_END(bpf_task_set) This set encodes the BTF ID of each kfunc listed above, and encodes the flags along with it. Ofcourse, it is also allowed to specify no flags. @@ -347,10 +347,10 @@ Once the kfunc is prepared for use, the final step to making it visible is registering it with the BPF subsystem. Registration is done per BPF program type. An example is shown below:: - BTF_SET8_START(bpf_task_set) + BTF_KFUNCS_START(bpf_task_set) BTF_ID_FLAGS(func, bpf_get_task_pid, KF_ACQUIRE | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_put_pid, KF_RELEASE) - BTF_SET8_END(bpf_task_set) + BTF_KFUNCS_END(bpf_task_set) static const struct btf_kfunc_id_set bpf_task_kfunc_set = { .owner = THIS_MODULE, |