Em Tue, Feb 05, 2019 at 11:24:44PM -0800, Andrii Nakryiko escreveu:
> This is my initial take on how to start using libbpf from pahole with the intent
> to reuse as much functionality from libbpf as possible. This is also necessary
> to do BTF deduplication, because btf__dedup() is implemented only as part of
> libbpf.
>
> Patch #2 adds submodule and corresponding cmake changes to build against libbpf.
> Patch #3 removes pahole's btf.h copy and references one from libbpf to test
> that libbpf is usable.
>
> If this approach will be deemed good, I'll continue refactoring of btf_encoder
> and btf_loader to utilize libbpf more fully and also use btf__dedup.
I think the approach is good, the end result is a working pahole:
[acme@quaco pahole]$ pahole -F btf examples/dedup-btf/a
struct foo {
int a; /* 0 4 */
char b; /* 4 1 */
/* size: 8, cachelines: 1, members: 2 */
/* padding: 3 */
/* last cacheline: 8 bytes */
};
struct bar {
int d; /* 0 4 */
char e; /* 4 1 */
unsigned char f; /* 5 1 */
/* size: 8, cachelines: 1, members: 3 */
/* padding: 2 */
/* last cacheline: 8 bytes */
};
[acme@quaco pahole]$ file examples/dedup-btf/a
examples/dedup-btf/a: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=67ed8ec4f73c807666afd75c9584dbcfc3222915, with debug_info, not stripped
[acme@quaco pahole]$ readelf -SW examples/dedup-btf/a | grep BTF
[34] .BTF PROGBITS 0000000000000000 004454 0000eb 00 0 0 1
[acme@quaco pahole]$
So either resubmit this or let me know if I can keep these on and you
can continue on top of it, ok?
At some point we just switch to linking dynamicly with libbtf, when it
becomes more generally available.
Thanks,
- Arnaldo
