From: <andrii.nakryiko@xxxxxxxxx> Date: Tue, 2 Apr 2019 09:49:50 -0700 > From: Andrii Nakryiko <andriin@xxxxxx> > > This patch adds new config option to trigger generation of BTF type > information from DWARF debuginfo for vmlinux and kernel modules through > pahole, which in turn relies on libbpf for btf_dedup() algorithm. > > The intent is to record compact type information of all types used > inside kernel, including all the structs/unions/typedefs/etc. This > enables BPF's compile-once-run-everywhere ([0]) approach, in which > tracing programs that are inspecting kernel's internal data (e.g., > struct task_struct) can be compiled on a system running some kernel > version, but would be possible to run on other kernel versions (and > configurations) without recompilation, even if the layout of structs > changed and/or some of the fields were added, removed, or renamed. > > This is only possible if BPF loader can get kernel type info to adjust > all the offsets correctly. This patch is a first time in this direction, > making sure that BTF type info is part of Linux kernel image in > non-loadable ELF section. > > BTF deduplication ([1]) algorithm typically provides 100x savings > compared to DWARF data, so resulting .BTF section is not big as is > typically about 2MB in size. > > [0] http://vger.kernel.org/lpc-bpf2018.html#session-2 > [1] https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html > > Signed-off-by: Andrii Nakryiko <andriin@xxxxxx> Acked-by: David S. Miller <davem@xxxxxxxxxxxxx>
