From: "Jose E. Marchesi" <jose.marchesi@oracle.com>
To: Indu Bhagat <indu.bhagat@oracle.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] btf: emit linkage information in BTF_KIND_FUNC entries
Date: Tue, 12 Jul 2022 17:12:33 +0200 [thread overview]
Message-ID: <87r12q2wm6.fsf@oracle.com> (raw)
In-Reply-To: <c46e1701-6a76-c68c-a92b-c1a9f8c1da76@oracle.com> (Indu Bhagat's message of "Mon, 11 Jul 2022 13:37:20 -0700")
> On 7/8/22 11:30 AM, Jose E. Marchesi via Gcc-patches wrote:
>>
>> The kernel bpftool expects BTF_KIND_FUNC entries in BTF to include an
>> annotation reflecting the linkage of functions (static, global). For
>> whatever reason they (ab)use the `vlen' field of the BTF_KIND_FUNC entry
>> instead of adding a variable-part to the record like it is done with
>> other entry kinds.
>>
>
> For BTF Variables, we have the linkage information in the output
> section as "btv_linkage". To propagate that information from DWARF to
> BTF, we have the dvd_visibility in struct ctf_dvdef (in ctfc.h). Now
> that the linkage information is needed for the BTF_KIND_FUNC entries,
> what do you think about - adding something like dtd_visibility to
> ctf_dtdef.
>
> Updating the BTF format documentation will be useful
> https://www.kernel.org/doc/Documentation/bpf/btf.rst. Let's see what
> can be done for that...
>
> Also, adding some testcases with the current patch will be great.
>
> I have created PR debug/106263 "BTF_KIND_FUNC type does not encode
> linkage" to track this.
Sending V2 with the requested changes.
prev parent reply other threads:[~2022-07-12 15:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-08 18:30 Jose E. Marchesi
2022-07-11 20:37 ` Indu Bhagat
2022-07-12 15:12 ` Jose E. Marchesi [this message]
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