[PATCH bpf-next 1/2] bpf: Remove bpf_jit_enable=2 debugging mode
christophe.leroy at csgroup.eu
Fri May 14 16:34:07 AEST 2021
Le 23/04/2021 à 12:26, Quentin Monnet a écrit :
> 2021-04-23 09:19 UTC+0200 ~ Christophe Leroy <christophe.leroy at csgroup.eu>
>> I finally managed to cross compile bpftool with libbpf, libopcodes,
>> readline, ncurses, libcap, libz and all needed stuff. Was not easy but I
>> made it.
> Libcap is optional and bpftool does not use readline or ncurses. May I
> ask how you tried to build it?
>> Now, how do I use it ?
>> Let say I want to dump the jitted code generated from a call to
>> 'tcpdump'. How do I do that with 'bpftool prog dump jited' ?
>> I thought by calling this line I would then get programs dumped in a way
>> or another just like when setting 'bpf_jit_enable=2', but calling that
>> line just provides me some bpftool help text.
> Well the purpose of this text is to help you find the way to call
> bpftool to do what you want :). For dumping your programs' instructions,
> you need to tell bpftool what program to dump: Bpftool isn't waiting
> until you load a program to dump it, instead you need to load your
> program first and then tell bpftool to retrieve the instructions from
> the kernel. To reference your program you could use a pinned path, or
> first list the programs on your system with "bpftool prog show":
> # bpftool prog show
> 138: tracing name foo tag e54c922dfa54f65f gpl
> loaded_at 2021-02-25T01:32:30+0000 uid 0
> xlated 256B jited 154B memlock 4096B map_ids 64
> btf_id 235
Got the following error:
root at vgoip:~# ./bpftool prog show
libbpf: elf: endianness mismatch in pid_iter_bpf.
libbpf: failed to initialize skeleton BPF object 'pid_iter_bpf': -4003
Error: failed to open PID iterator skeleton
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