[PATCH v7 00/10] tracing/probes: Add more typecast features

[Masami Hiramatsu (Google)]

Hi,

Here is the 7th version of series to introduce more typecast features
to probe events. The previous version is here:

 https://lore.kernel.org/all/178201238795.570818.15573963115625446598.stgit@devnote2/

In this version, I added 2 new fix and cleanup patches and update
according to Sashiko's review. [1/10] is a long-lived issue about
@+FOFFS, which was wrongly adding offset twice. [2/10] is a clean
up patch for renaming fetch_op name (good to dump it). 
This is applicable against probes/core branch on linux-trace tree.

Steve introduced BTF typecast feature for eprobe[1].
This series extends it and add more options:

1. Expanding BTF typecast to kprobe and fprobe.
   (currently only function entry/exit)

2. Introduce container_of like typecast. This adds a "assigned
   member" option to the typecast.

   (STRUCT,MEMBER)VAR->ANOTHER_MEMBER

   This casts VAR to STRUCT type but the VAR is as the address
   of STRUCT.MEMBER. In C, it is:

   container_of(VAR, STRUCT, MEMBER)->ANOTHER_MEMBER

3. Support nested typecast, e.g.

   (STRUCT)((STRUCT2)VAR->MEMBER2)->MEMBER

   the nest level must be smaller than 3.

4. Add $current variable to point "current" task_struct.
   This is useful with typecast, e.g.

   (task_struct)$current->pid

5. per-cpu dereference support.

   Intrdouce this_cpu_read(VAR) and this_cpu_ptr(VAR) to
   access per-cpu data on the current CPU (accessing other CPU
   data is not stable, because it can be changed.)

   You can access the member of per-cpu data structure using
   typecast like:

   (STRUCT)this_cpu_ptr(VAR)->MEMBER

And added fetcharg dump feature (for debug) and updated test scripts
to test part of them.

Thanks,

---
base-commit: 3ec75d0067f30eb5e0730f033766d6ab2feca7ae

Masami Hiramatsu (Google) (10):
      tracing/probes: Fix double addition of offset for @+FOFFSET
      tracing/probes: Rename FETCH_OP_DATA to FETCH_OP_IMMSTR
      tracing/probes: Support dumping fetcharg program for debugging dynamic events
      tracing/probes: Support typecast for various probe events
      tracing/probes: Support nested typecast
      tracing/probes: Type casting always involves nested calls
      tracing/probes: Support field specifier option for typecast
      tracing/probes: Add $current variable support
      tracing/probes: Add this_cpu_read() and this_cpu_ptr() dereference method to fetcharg
      tracing/probes: Add a new testcase for BTF typecasts


 Documentation/trace/eprobetrace.rst                |    9 
 Documentation/trace/fprobetrace.rst                |   10 
 Documentation/trace/kprobetrace.rst                |   11 
 kernel/trace/Kconfig                               |   11 
 kernel/trace/trace.c                               |    8 
 kernel/trace/trace_eprobe.c                        |    2 
 kernel/trace/trace_fprobe.c                        |    2 
 kernel/trace/trace_kprobe.c                        |    2 
 kernel/trace/trace_probe.c                         |  582 ++++++++++++++++----
 kernel/trace/trace_probe.h                         |   98 ++-
 kernel/trace/trace_probe_tmpl.h                    |   27 +
 kernel/trace/trace_uprobe.c                        |    3 
 samples/trace_events/trace-events-sample.c         |   40 +
 samples/trace_events/trace-events-sample.h         |   34 +
 .../ftrace/test.d/dynevent/btf_probe_event.tc      |   51 ++
 .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc |   11 
 .../ftrace/test.d/kprobe/kprobe_syntax_errors.tc   |   11 
 .../ftrace/test.d/kprobe/uprobe_syntax_errors.tc   |    5 
 18 files changed, 756 insertions(+), 161 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/btf_probe_event.tc

--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>