netdev - Re: [PATCH bpf-next 0/3] bpf: add dumping and disassembler for non-host JITs

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Date:   Tue, 16 Jan 2018 16:28:49 -0800
From:   Jakub Kicinski <jakub.kicinski@...ronome.com>
To:     daniel@...earbox.net, alexei.starovoitov@...il.com
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com
Subject: Re: [PATCH bpf-next 0/3] bpf: add dumping and disassembler for
 non-host JITs

On Tue, 16 Jan 2018 16:05:18 -0800, Jakub Kicinski wrote:
> Hi,

Ah, forgot to insert "Jiong says:" here :)

> Currently bpftool could disassemble host jited image, for example x86_64,
> using libbfd. However it couldn't disassemble offload jited image.
> 
> There are two reasons:
> 
>   1. bpf_obj_get_info_by_fd/struct bpf_prog_info couldn't get the address
>      of jited image and image's length.
> 
>   2. Even after issue 1 resolved, bpftool couldn't figure out what is the
>      offload arch from bpf_prog_info, therefore can't drive libbfd
>      disassembler correctly.
> 
>   This patch set resolve issue 1 by introducing two new fields "jited_len"
> and "jited_image" in bpf_dev_offload. These two fields serve as the generic
> interface to communicate the jited image address and length for all offload
> targets to higher level caller. For example, bpf_obj_get_info_by_fd could
> use them to fill the userspace visible fields jited_prog_len and
> jited_prog_insns.
> 
>   This patch set resolve issue 2 by getting bfd backend name through
> "ifindex", i.e network interface index.
> 
> v1:
>  - Deduct bfd arch name through ifindex, i.e network interface index.
>    First, map ifindex to devname through ifindex_to_name_ns, then get
>    pci id through /sys/class/dev/DEVNAME/device/vendor. (Daniel, Alexei)