On Fri, Jul 26, 2019 at 2:19 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > > On Fri, Jul 26, 2019 at 11:10 PM Yonghong Song <yhs@xxxxxx> wrote: > > > > > > > > On 7/26/19 2:02 PM, Sedat Dilek wrote: > > > On Fri, Jul 26, 2019 at 10:38 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote: > > >> > > >> Hi Yonghong Song, > > >> > > >> On Fri, Jul 26, 2019 at 5:45 PM Yonghong Song <yhs@xxxxxx> wrote: > > >>> > > >>> > > >>> > > >>> On 7/26/19 1:26 AM, Sedat Dilek wrote: > > >>>> Hi, > > >>>> > > >>>> I have opened a new issue in the ClangBuiltLinux issue tracker. > > >>> > > >>> Glad to know clang 9 has asm goto support and now It can compile > > >>> kernel again. > > >>> > > >> > > >> Yupp. > > >> > > >>>> > > >>>> I am seeing a problem in the area bpf/seccomp causing > > >>>> systemd/journald/udevd services to fail. > > >>>> > > >>>> [Fri Jul 26 08:08:43 2019] systemd[453]: systemd-udevd.service: Failed > > >>>> to connect stdout to the journal socket, ignoring: Connection refused > > >>>> > > >>>> This happens when I use the (LLVM) LLD ld.lld-9 linker but not with > > >>>> BFD linker ld.bfd on Debian/buster AMD64. > > >>>> In both cases I use clang-9 (prerelease). > > >>> > > >>> Looks like it is a lld bug. > > >>> > > >>> I see the stack trace has __bpf_prog_run32() which is used by > > >>> kernel bpf interpreter. Could you try to enable bpf jit > > >>> sysctl net.core.bpf_jit_enable = 1 > > >>> If this passed, it will prove it is interpreter related. > > >>> > > >> > > >> After... > > >> > > >> sysctl -w net.core.bpf_jit_enable=1 > > >> > > >> I can start all failed systemd services. > > >> > > >> systemd-journald.service > > >> systemd-udevd.service > > >> haveged.service > > >> > > >> This is in maintenance mode. > > >> > > >> What is next: Do set a permanent sysctl setting for net.core.bpf_jit_enable? > > >> > > > > > > This is what I did: > > > > I probably won't have cycles to debug this potential lld issue. > > Maybe you already did, I suggest you put enough reproducible > > details in the bug you filed against lld so they can take a look. > > > > I understand and will put the journalctl-log into the CBL issue > tracker and update informations. > > Thanks for your help understanding the BPF correlations. > > Is setting 'net.core.bpf_jit_enable = 2' helpful here? jit_enable=1 is enough. Or use CONFIG_BPF_JIT_ALWAYS_ON to workaround. It sounds like clang miscompiles interpreter. modprobe test_bpf should be able to point out which part of interpreter is broken.
