bpf: Add support for sleepable tracepoint programs

This series adds support for sleepable BPF programs attached to raw
tracepoints (tp_btf), classic raw tracepoints (raw_tp), and classic
tracepoints (tp). 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.

This series removes restriction for faultable tracepoints:

Patch 1 modifies __bpf_trace_run() to support sleepable programs
following the uprobe_prog_run() pattern: use explicit
rcu_read_lock_trace() for sleepable programs and rcu_read_lock() for
non-sleepable programs. Also removes preempt_disable from the faultable
tracepoint BPF callback wrapper, since migration protection and RCU
locking are now managed per-program inside __bpf_trace_run().

Patch 2 renames bpf_prog_run_array_uprobe() to
bpf_prog_run_array_sleepable() to support new usecase.

Patch 3 adds sleepable support for classic tracepoints
(BPF_PROG_TYPE_TRACEPOINT) by introducing trace_call_bpf_faultable()
and restructuring perf_syscall_enter/exit() to run BPF programs in
faultable context before the preempt-disabled per-cpu buffer
allocation. trace_call_bpf_faultable() uses rcu_tasks_trace for
lifetime protection, following the uprobe pattern. This adds
rcu_tasks_trace overhead for all classic tracepoint BPF programs on
syscall tracepoints, not just sleepable ones.

Patch 4 allows BPF_TRACE_RAW_TP, BPF_PROG_TYPE_RAW_TRACEPOINT, and
BPF_PROG_TYPE_TRACEPOINT programs to be loaded as sleepable, with
load-time and attach-time checks to reject sleepable programs on
non-faultable tracepoints.

Patch 5 adds libbpf SEC_DEF handlers: tp_btf.s, raw_tp.s,
raw_tracepoint.s, tp.s, and tracepoint.s.

Patch 6 adds selftests covering tp_btf.s, raw_tp.s, and tp.s positive
cases using bpf_copy_from_user() on sys_enter nanosleep, plus negative
tests for non-faultable tracepoints.

Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
---
Changes in v7:
- Add recursion check (bpf_prog_get_recursion_context()) to make sure
private stack is safe when sleepable program is preempted by itself
(Alexei, Kumar)
- Use combined rcu_read_lock_dont_migrate() instead of separate
rcu_read_lock()/migrate_disable() calls for non-sleepable path (Alexei)
- Link to v6: https://lore.kernel.org/bpf/20260324-sleepable_tracepoint...

Changes in v6:
- Remove recursion check from trace_call_bpf_faultable(), sleepable
tracepoints are called from syscall enter/exit, no recursion is
possible.(Kumar)
- Refactor bpf_prog_run_array_uprobe() to support tracepoints
usecase cleanly (Kumar)
- Link to v5: https://lore.kernel.org/r/20260316-sleepable_tracepoints-...

Changes in v5:
- Addressed AI review: zero initialize struct pt_regs in
perf_call_bpf_enter(); changed handling tp.s and tracepoint.s in
attach_tp() in libbpf.
- Updated commit messages
- Link to v4: https://lore.kernel.org/r/20260313-sleepable_tracepoints-...

Changes in v4:
- Follow uprobe_prog_run() pattern with explicit rcu_read_lock_trace()
  instead of relying on outer rcu_tasks_trace lock
- Add sleepable support for classic raw tracepoints (raw_tp.s)
- Add sleepable support for classic tracepoints (tp.s) with new
  trace_call_bpf_faultable() and restructured perf_syscall_enter/exit()
- Add raw_tp.s, raw_tracepoint.s, tp.s, tracepoint.s SEC_DEF handlers
- Replace growing type enumeration in error message with generic
  "program of this type cannot be sleepable"
- Use PT_REGS_PARM1_SYSCALL (non-CO-RE) in BTF test
- Add classic raw_tp and classic tracepoint sleepable tests
- Link to v3: https://lore.kernel.org/r/20260311-sleepable_tracepoints-...

Changes in v3:
  - Moved faultable tracepoint check from attach time to load time in
    bpf_check_attach_target(), providing a clear verifier error message
  - Folded preempt_disable removal into the sleepable execution path
    patch
  - Used RUN_TESTS() with __failure/__msg for negative test case instead
    of explicit userspace program
  - Reduced series from 6 patches to 4
  - Link to v2: https://lore.kernel.org/r/20260225-sleepable_tracepoints-...

Changes in v2:
  - Address AI review points - modified the order of the patches
  - Link to v1: https://lore.kernel.org/bpf/20260218-sleepable_tracepoint...

---
Mykyta Yatsenko (6):
      bpf: Add sleepable support for raw tracepoint programs
      bpf: Rename bpf_prog_run_array_uprobe() to bpf_prog_run_array_sleepable()
      bpf: Add sleepable support for classic tracepoint programs
      bpf: Verifier support for sleepable tracepoint programs
      libbpf: Add section handlers for sleepable tracepoints
      selftests/bpf: Add tests for sleepable tracepoint programs

 include/linux/bpf.h                                |  24 +++-
 include/linux/trace_events.h                       |   6 +
 include/trace/bpf_probe.h                          |   2 -
 kernel/bpf/syscall.c                               |   5 +
 kernel/bpf/verifier.c                              |  13 ++-
 kernel/events/core.c                               |   9 ++
 kernel/trace/bpf_trace.c                           |  49 ++++++++-
 kernel/trace/trace_syscalls.c                      | 110 ++++++++++---------
 kernel/trace/trace_uprobe.c                        |   2 +-
 tools/lib/bpf/libbpf.c                             |  39 +++++--
 .../bpf/prog_tests/sleepable_tracepoints.c         | 121 +++++++++++++++++++++
 .../bpf/progs/test_sleepable_tracepoints.c         | 117 ++++++++++++++++++++
 .../bpf/progs/test_sleepable_tracepoints_fail.c    |  18 +++
 tools/testing/selftests/bpf/verifier/sleepable.c   |  17 ++-
 14 files changed, 459 insertions(+), 73 deletions(-)
---
base-commit: 6c8e1a9eee0fec802b542dadf768c30c2a183b3c
change-id: 20260216-sleepable_tracepoints-381ae1410550

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