Em Wed, Apr 03, 2019 at 11:12:58AM +0200, Jiri Olsa escreveu: > On Wed, Apr 03, 2019 at 11:04:28AM +0200, Daniel Borkmann wrote: > > On 04/03/2019 10:46 AM, Jiri Olsa wrote: > > > On Tue, Apr 02, 2019 at 09:49:50AM -0700, andrii.nakryiko@xxxxxxxxx wrote: > > >> 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. > > > > > > hi, > > > I'm using the latest pahole from git tree: > > > https://github.com/acmel/dwarves.git > > > > > > and getting pahole crash: > > > > > > LD vmlinux > > > BTF vmlinux > > > die__process_inline_expansion: DW_TAG_label (0xa) @ <0x3eef8> not handled! > > > scripts/link-vmlinux.sh: line 96: 31222 Segmentation fault (core dumped) LLVM_OBJCOPY=${OBJCOPY} ${PAHOLE} -J ${1} > > > make[1]: *** [/home/jolsa/linux/Makefile:1025: vmlinux] Error 139 > > > make: *** [Makefile:170: sub-make] Error 2 > > > > > > is there some other source/dependency I'm missing? > > > > Yesterday night, I've tested with [0] but seems to have the same HEAD as > > the github repo you pointed out. Seems the above is coming from pahole's > > __die__process_tag() bailing out with default for DW_TAG_label? > > > > On my side worked fine: > > hum, I also had to change the version of pahole in the patch to allow > version v1.12, because both latest pahole sources are on version 1.12, > did u have to do that? looks like there's v1.13 somewhere ;-) I'll get the --reorganize algorithm simplified to cope with some internal changes needed for the BTF encoding/decoding and tag v1.13 later today, max late this week. Then I'll go back adding the bitfield reorganization bits that will take a bit more work. Hopefully this way we get something to work with the Kbuild changes and have progress in that front. I'll look at the DW_TAG_label case too, please send me me in PVT the vmlinux file with that problem so that I can analyse it. > jirka > > SNIP > > > > > [0] https://git.kernel.org/pub/scm/devel/pahole/pahole.git/
