bpf: Add support for sleepable raw tracepoint programs

This series adds support for sleepable BPF programs attached to raw
tracepoints (tp_btf). The motivation is to allow BPF programs on
syscall tracepoints to use sleepable helpers such as
bpf_copy_from_user(), enabling reliable user memory reads that can
page-fault.

Currently, raw tracepoint BPF programs always run with RCU read lock
held and preemption disabled, which prevents calling any helper that
might sleep. Faultable tracepoints (__DECLARE_TRACE_SYSCALL) already
run under rcu_tasks_trace protection in process context where sleeping
is safe.

This series removes that restriction for faultable tracepoints:

Patch 1 allows BPF_TRACE_RAW_TP programs to be loaded as sleepable.
The actual enforcement is deferred to attach time since the target
tracepoint is not known during load.

Patch 2 adds an attach-time check to reject sleepable programs on
non-faultable tracepoints (e.g., sched_switch) that may run in NMI
or other non-sleepable contexts.

Patch 3 modifies __bpf_trace_run() to support sleepable programs:
delete cant_sleep(), use migrate_disable() instead of rcu_read_lock(),
and rely on the outer rcu_tasks_trace lock from the faultable
tracepoint callback for program lifetime protection.

Patch 4 removes preempt_disable from the faultable tracepoint BPF
callback wrapper, since preemption management is now handled
per-program inside __bpf_trace_run().

Patch 5 adds the tp_btf.s section handler in libbpf, following the
existing pattern of fentry.s/fexit.s/lsm.s.

Patch 6 adds selftests covering both the positive case (sleepable
program on sys_enter using bpf_copy_from_user() to read user memory)
and the negative case (sleepable program rejected on sched_switch).

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
Mykyta Yatsenko (6):
      bpf: Allow sleepable programs for BPF_TRACE_RAW_TP attach type
      bpf: Reject sleepable raw_tp programs on non-faultable tracepoints
      bpf: Remove preempt_disable from faultable tracepoint BPF callbacks
      bpf: Add sleepable execution path for raw tracepoint programs
      libbpf: Add tp_btf.s section handler for sleepable raw tracepoints
      selftests/bpf: Add tests for sleepable raw tracepoint programs

 include/trace/bpf_probe.h                          |  2 -
 kernel/bpf/syscall.c                               |  5 ++
 kernel/bpf/verifier.c                              |  3 +-
 kernel/trace/bpf_trace.c                           | 22 +++++++--
 tools/lib/bpf/libbpf.c                             |  1 +
 .../selftests/bpf/prog_tests/sleepable_raw_tp.c    | 56 ++++++++++++++++++++++
 .../selftests/bpf/progs/test_sleepable_raw_tp.c    | 43 +++++++++++++++++
 .../bpf/progs/test_sleepable_raw_tp_fail.c         | 16 +++++++
 tools/testing/selftests/bpf/verifier/sleepable.c   |  5 +-
 9 files changed, 143 insertions(+), 10 deletions(-)
---
base-commit: 4c51f90d45dca71e7974ed5a7c40b9c04a6c6762
change-id: 20260216-sleepable_tracepoints-381ae1410550

Best regards,
-- 
Mykyta Yatsenko <yatsenko@meta.com>