Supporting bpf_asm syntax in strace

[Elazar Leibovich]

I sent a patch to the mailing list like in the good old days.

Do you prefer github PR?

Let me know.

On Tue, Jun 5, 2018 at 7:36 PM, Eugene Syromiatnikov <esyr at redhat.com>
wrote:

> On Tue, Jun 05, 2018 at 07:13:45PM +0300, Elazar Leibovich wrote:
> > Hi,
> >
> > Currently the format in which BPF programs are printed, is an strace
> > specific format.
> >
> > It's a fine format, but, except of being verbose, it's incompatible with
> > kernel's tooling.
> >
> > Currently abbreviated format, and none-verbose format are identical.
> >
> > I therefor suggest the following:
> >
> > None-verbose format would remain as it is today. That is, printout of the
> > BPF program address only without traversing it, like the man page says.
> >
> > Verbose and abbreviated format, would be the bpf_asm format of <len>,<op>
> > <jt> <jf>  <k>,.... which is indeed shorter.
> >
> > Verbose and none-abbreviated format would be the current format.
> >
> > The main advantage of my proposal is that in bpf_asm compatible mode, you
> > can dump it to  bpf_debug, run it, dump it etc. I'm not aware of tooling
> > that supports the current format.
> >
> > I have a patch to submit, if you think this is a good solution.
> >
> > What do you think?
>
> I'm actually planning to continue improving BPF program output format,
> as there is a lot of work to do, and making it closer to verifier/bpftool
> output is on my todo list, so, yeah, the patch like that will be pretty
> much appreciated.
>
> But, there are two things I have in my mind:
>  * We try to stick to C-like syntax as much as possible, so, for a BPF
>    assembly dump some syntax should be invented for printing those dumps
>    (like, enclose it in some combination of braces/quotes/...).
>  * I'm also thinking about (and leaning to) I/O dump-like format, when
>    program disassembly is printed after the syscall.
> --
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>
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