docs/bpf: Update documentation for BTF_KIND_FUNC

The vlen bits in the BTF type of kind BTF_KIND_FUNC are used to convey the
linkage information for functions. The Linux kernel only supports
linkage values of BTF_FUNC_STATIC and BTF_FUNC_GLOBAL at this time.

Signed-off-by: Indu Bhagat <indu.bhagat@oracle.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220714223310.1140097-1-indu.bhagat@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Indu Bhagat 2022-07-14 15:33:10 -07:00 committed by Alexei Starovoitov
parent 3908fcddc6
commit e5e23424e5
1 changed files with 5 additions and 1 deletions

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@ -369,7 +369,8 @@ No additional type data follow ``btf_type``.
* ``name_off``: offset to a valid C identifier
* ``info.kind_flag``: 0
* ``info.kind``: BTF_KIND_FUNC
* ``info.vlen``: 0
* ``info.vlen``: linkage information (BTF_FUNC_STATIC, BTF_FUNC_GLOBAL
or BTF_FUNC_EXTERN)
* ``type``: a BTF_KIND_FUNC_PROTO type
No additional type data follow ``btf_type``.
@ -380,6 +381,9 @@ type. The BTF_KIND_FUNC may in turn be referenced by a func_info in the
:ref:`BTF_Ext_Section` (ELF) or in the arguments to :ref:`BPF_Prog_Load`
(ABI).
Currently, only linkage values of BTF_FUNC_STATIC and BTF_FUNC_GLOBAL are
supported in the kernel.
2.2.13 BTF_KIND_FUNC_PROTO
~~~~~~~~~~~~~~~~~~~~~~~~~~