Re: [PATCH] tools: bpf_jit_disasm: Add option to dump JIT image to a file.

[David Daney]

On 04/11/2017 02:54 PM, Daniel Borkmann wrote:
> On 04/11/2017 11:30 PM, David Daney wrote:
> > When debugging the JIT on an embedded platform or cross build
> > environment, libbfd may not be available, making it impossible to run
> > bpf_jit_disasm natively.
> >
> > Add an option to emit a binary image of the JIT code to a file.  This
> > file can then be disassembled off line.  Typical usage in this case
> > might be (pasting mips64 dmesg output to cat command):
> >
> >     $ cat > jit.raw
> >     $ bpf_jit_disasm -f jit.raw -O jit.bin
> >     $ mips64-linux-gnu-objdump -D -b binary -m mips:isa64r2 -EB jit.bin
> >
> > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
>
> Seems good, we could at some point also add an -I jit.bin option
> if needed for offline analysis/comparison instead of using -f
> plain text.

FWIW:  The objdump incantation in the changelog does just about the same 
disassembly as the bpf_jit_disasm internal implementation.

> Thanks!
>
> Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>