This is based on top of the deferred unwind core patch series:

  https://lore.kernel.org/linux-trace-kernel/20250611005421.144238328@goodmis.org/

Which is based on top of v6.16-rc1.

This series implements the perf interface to use deferred user space stack
tracing. I'm posting this now for review and comments and a way for people to
test out the unwind deferred core series. As this has updates to user ABI it
should be scrutinized much more as once this is accepted it is set in stone.
This is why this is a separate patch series.

Changes since v8: https://lore.kernel.org/linux-trace-kernel/20250509164524.448387100@goodmis.org/

- Simply rebased on top of the latest unwind deferred core.

- This still has issues that were brought up in v8 by Andii regarding
  cross_task and user vs kernel stack tracing. I did not yet address these
  concerns as I just wanted to get this series out based on v6.16-rc*.

  https://lore.kernel.org/linux-trace-kernel/CAEf4BzaKfvCu2T+jJ2e-CCt0N50urfx+p6kQfV899_jkmT_XKQ@mail.gmail.com/

Josh Poimboeuf (5):
      perf: Remove get_perf_callchain() init_nr argument
      perf: Have get_perf_callchain() return NULL if crosstask and user are set
      perf: Simplify get_perf_callchain() user logic
      perf: Skip user unwind if the task is a kernel thread
      perf: Support deferred user callchains

Namhyung Kim (4):
      perf tools: Minimal CALLCHAIN_DEFERRED support
      perf record: Enable defer_callchain for user callchains
      perf script: Display PERF_RECORD_CALLCHAIN_DEFERRED
      perf tools: Merge deferred user callchains

Steven Rostedt (2):
      perf: Use current->flags & PF_KTHREAD instead of current->mm == NULL
      perf: Support deferred user callchains for per CPU events

----
 arch/Kconfig                              |   3 +
 include/linux/perf_event.h                |  14 +-
 include/uapi/linux/perf_event.h           |  19 +-
 kernel/bpf/stackmap.c                     |   8 +-
 kernel/events/callchain.c                 |  47 ++--
 kernel/events/core.c                      | 352 +++++++++++++++++++++++++++++-
 tools/include/uapi/linux/perf_event.h     |  19 +-
 tools/lib/perf/include/perf/event.h       |   7 +
 tools/perf/Documentation/perf-script.txt  |   5 +
 tools/perf/builtin-script.c               |  92 ++++++++
 tools/perf/util/callchain.c               |  24 ++
 tools/perf/util/callchain.h               |   3 +
 tools/perf/util/event.c                   |   1 +
 tools/perf/util/evlist.c                  |   1 +
 tools/perf/util/evlist.h                  |   1 +
 tools/perf/util/evsel.c                   |  39 ++++
 tools/perf/util/evsel.h                   |   1 +
 tools/perf/util/machine.c                 |   1 +
 tools/perf/util/perf_event_attr_fprintf.c |   1 +
 tools/perf/util/sample.h                  |   3 +-
 tools/perf/util/session.c                 |  78 +++++++
 tools/perf/util/tool.c                    |   2 +
 tools/perf/util/tool.h                    |   4 +-
 23 files changed, 691 insertions(+), 34 deletions(-)