Merge branch 'bpf-sleepable'

Merge branch 'bpf-sleepable'

Alexei Starovoitov says:

====================
v2->v3:
- switched to minimal allowlist approach. Essentially that means that syscall
  entry, few btrfs allow_error_inject functions, should_fail_bio(), and two LSM
  hooks: file_mprotect and bprm_committed_creds are the only hooks that allow
  attaching of sleepable BPF programs. When comprehensive analysis of LSM hooks
  will be done this allowlist will be extended.
- added patch 1 that fixes prototypes of two mm functions to reliably work with
  error injection. It's also necessary for resolve_btfids tool to recognize
  these two funcs, but that's secondary.

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

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.

Here is 'perf report' difference of sleepable vs non-sleepable:
   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
vs
   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
vs
   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

Sleepable vs non-sleepable program invocation overhead is only marginally higher
due to rcu_trace. srcu approach is much slower.
====================

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>