On Tue, Apr 2, 2024 at 12:45 PM Arnaldo Carvalho de Melo
<acme@xxxxxxxxxx> wrote:
>
> On Tue, Apr 02, 2024 at 11:45:43AM -0700, Namhyung Kim wrote:
> > I got a report for a failure in BPF verifier on a recent kernel with
> > perf lock contention command. It checks task->sighand->siglock without
> > checking if sighand is NULL or not. Let's add one.
> >
> > ; if (&curr->sighand->siglock == (void *)lock)
> > 265: (79) r1 = *(u64 *)(r0 +2624) ; frame1: R0_w=trusted_ptr_task_struct(off=0,imm=0) R1_w=rcu_ptr_or_null_sighand_struct(off=0,imm=0)
> > 266: (b7) r2 = 0 ; frame1: R2_w=0
> > 267: (0f) r1 += r2
> > R1 pointer arithmetic on rcu_ptr_or_null_ prohibited, null-check it first
> > processed 164 insns (limit 1000000) max_states_per_insn 1 total_states 15 peak_states 15 mark_read 5
> > -- END PROG LOAD LOG --
> > libbpf: prog 'contention_end': failed to load: -13
> > libbpf: failed to load object 'lock_contention_bpf'
> > libbpf: failed to load BPF skeleton 'lock_contention_bpf': -13
> > Failed to load lock-contention BPF skeleton
> > lock contention BPF setup failed
> > lock contention did not detect any lock contention
> >
> > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
>
> Acked-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
>
> Are you going to have this merged into perf-tools?
>
> A Fixes: tag isn't perhaps needed as it worked in the past?
Fixes: 1811e82767dcc ("perf lock contention: Track and show siglock
with address")
It was introduced in v6.4 and it should be fine to have this
even without the error. I'll queue it to perf-tools.
Thanks,
Namhyung
