[PATCH RFC v3 bpf-next 0/4] bpf: Introduce minimal support for sleepable progs

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

From: Alexei Starovoitov <ast@kernel.org>

v2->v3:
- switched to rcu_trace
- added bpf_copy_from_user

Here is 'perf report' differences:
sleepable with SRCU:
   3.86%  bench     [k] __srcu_read_unlock
   3.22%  bench     [k] __srcu_read_lock
   0.92%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
   0.50%  bench     [k] bpf_trampoline_10297
   0.26%  bench     [k] __bpf_prog_exit_sleepable
   0.21%  bench     [k] __bpf_prog_enter_sleepable

sleepable with RCU_TRACE:
   0.79%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry_sleep
   0.72%  bench     [k] bpf_trampoline_10381
   0.31%  bench     [k] __bpf_prog_exit_sleepable
   0.29%  bench     [k] __bpf_prog_enter_sleepable

non-sleepable with RCU:
   0.88%  bench     [k] bpf_prog_740d4210cdcd99a3_bench_trigger_fentry
   0.84%  bench     [k] bpf_trampoline_10297
   0.13%  bench     [k] __bpf_prog_enter
   0.12%  bench     [k] __bpf_prog_exit

Happy to confirm that rcu_trace overhead is negligible.

v1->v2:
- split fmod_ret fix into separate patch
- added blacklist

v1:
This patch set introduces the minimal viable support for sleepable bpf programs.
In this patch only fentry/fexit/fmod_ret and lsm progs can be sleepable.
Only array and pre-allocated hash and lru maps allowed.

Alexei Starovoitov (4):
  bpf: Introduce sleepable BPF programs
  bpf: Add bpf_copy_from_user() helper.
  libbpf: support sleepable progs
  selftests/bpf: basic sleepable tests

 arch/x86/net/bpf_jit_comp.c                   | 32 ++++++----
 include/linux/bpf.h                           |  4 ++
 include/uapi/linux/bpf.h                      | 19 +++++-
 init/Kconfig                                  |  1 +
 kernel/bpf/arraymap.c                         |  6 ++
 kernel/bpf/hashtab.c                          | 20 ++++--
 kernel/bpf/helpers.c                          | 22 +++++++
 kernel/bpf/syscall.c                          | 13 +++-
 kernel/bpf/trampoline.c                       | 37 ++++++++---
 kernel/bpf/verifier.c                         | 62 ++++++++++++++++++-
 kernel/trace/bpf_trace.c                      |  2 +
 tools/include/uapi/linux/bpf.h                | 19 +++++-
 tools/lib/bpf/libbpf.c                        | 25 +++++++-
 tools/testing/selftests/bpf/bench.c           |  2 +
 .../selftests/bpf/benchs/bench_trigger.c      | 17 +++++
 tools/testing/selftests/bpf/progs/lsm.c       | 14 ++++-
 .../selftests/bpf/progs/trigger_bench.c       |  7 +++
 17 files changed, 268 insertions(+), 34 deletions(-)

-- 
2.23.0