[PATCH 0/6] tracing/boot: Start boot-time tracing in earlier stage

[Masami Hiramatsu <mhiramat@kernel.org>]

Hi,

Here is a series of patches which starts the boot-time tracing earlier,
core_initcall_sync, so that we can start tracing from postcore_initcall
instead of device_initcall.

The boot-time tracing is useful for debugging kernel drivers which are
embedded in the kernel. Since most of the drivers are initialized in the
device_initcall, the boot-time tracing which starts in fs_initcall, can
trace them. However, many frameworks and platform drivers are initialized
in subsys_initcall or arch_initcall and the boot-time tracing still
misses it.

This series will improve the boot-time tracing to trace those events.

- Move kprobes initialization into early_initcall from subsys_initcall
  as same as jump_label and dynamic_debug.
  Previously arm64 didn't allow it, but commit b322c65f8ca3 ("arm64:
  Call debug_traps_init() from trap_init() to help early kgdb") fixed it.
- Fixes tracing init routines to decouple the tracefs entry creation
  and the data-structure allocation/initialization.
- Move dynamic-events initialization to core_initcall and call boot-time
  tracing in core_initcall_sync (the core_initcall_sync is called after
  all core_initcall functions are done).

Thank you,

---

Masami Hiramatsu (6):
      kprobes: Init kprobes in early_initcall
      tracing: Define event fields early stage
      tracing: Enable adding dynamic events early stage
      tracing: Enable creating new instance early boot
      tracing/boot,kprobe,synth: Initialize boot-time tracing earlier
      Documentation: tracing: Add the startup timing of boot-time tracing


 Documentation/trace/boottime-trace.rst |   14 ++++
 kernel/kprobes.c                       |    2 -
 kernel/trace/trace.c                   |   53 +++++++++++++----
 kernel/trace/trace.h                   |    7 ++
 kernel/trace/trace_boot.c              |    7 ++
 kernel/trace/trace_events.c            |  101 ++++++++++++++++++++------------
 kernel/trace/trace_events_synth.c      |   22 +++++--
 kernel/trace/trace_functions.c         |   22 ++++---
 kernel/trace/trace_kprobe.c            |    6 +-
 9 files changed, 165 insertions(+), 69 deletions(-)

--
Masami Hiramatsu (Linaro) <mhiramat@kernel.org>