[PATCH bpf-next v3] docs/bpf: Update documentation for BTF_KIND_FUNC

[PATCH bpf-next v3] docs/bpf: Update documentation for BTF_KIND_FUNC

[Indu Bhagat]

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>
---
 Documentation/bpf/btf.rst | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
index f49aeef62d0c..cf8722f96090 100644
--- a/Documentation/bpf/btf.rst
+++ b/Documentation/bpf/btf.rst
@@ -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
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-- 
2.31.1

Re: [PATCH bpf-next v3] docs/bpf: Update documentation for BTF_KIND_FUNC

[Andrii Nakryiko]

On Thu, Jul 14, 2022 at 3:33 PM Indu Bhagat <indu.bhagat@oracle.com> wrote:
>
> 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>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  Documentation/bpf/btf.rst | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/bpf/btf.rst b/Documentation/bpf/btf.rst
> index f49aeef62d0c..cf8722f96090 100644
> --- a/Documentation/bpf/btf.rst
> +++ b/Documentation/bpf/btf.rst
> @@ -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
>  ~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> --
> 2.31.1
>

Re: [PATCH bpf-next v3] docs/bpf: Update documentation for BTF_KIND_FUNC

[Martin KaFai Lau]

On Thu, Jul 14, 2022 at 03:33:10PM -0700, Indu Bhagat wrote:
> 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.
Acked-by: Martin KaFai Lau <kafai@fb.com>

Re: [PATCH bpf-next v3] docs/bpf: Update documentation for BTF_KIND_FUNC

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Thu, 14 Jul 2022 15:33:10 -0700 you wrote:
> 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>
> ---
>  Documentation/bpf/btf.rst | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)

Here is the summary with links:
  - [bpf-next,v3] docs/bpf: Update documentation for BTF_KIND_FUNC
    https://git.kernel.org/bpf/bpf-next/c/e5e23424e51e

You are awesome, thank you!
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