Hi, Here is the 2nd version of series to introduce more typecast features to probe events. The previous version is here:
https://lore.kernel.org/all/178092865666.163648.10457567771536160909.stgit@devnote2/ In this version, I fixed various problems Sashiko reviewed and add a fix of sample code. Also drop +CPU/PCPU() and introduce this_cpu_read(). 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 a test script to test part of them. [1] https://lore.kernel.org/all/[email protected]/ --- Masami Hiramatsu (Google) (7): tracing/events: Fix to check the simple_tsk_fn creation tracing/probes: Support typecast for various probe events tracing/probes: Support nested typecast 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 | 10 Documentation/trace/fprobetrace.rst | 10 Documentation/trace/kprobetrace.rst | 11 + kernel/trace/trace.c | 6 kernel/trace/trace_probe.c | 404 +++++++++++++++----- kernel/trace/trace_probe.h | 18 + kernel/trace/trace_probe_tmpl.h | 33 +- samples/trace_events/trace-events-sample.c | 56 ++- samples/trace_events/trace-events-sample.h | 34 ++ .../ftrace/test.d/dynevent/btf_probe_event.tc | 51 +++ 10 files changed, 509 insertions(+), 124 deletions(-) create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/btf_probe_event.tc -- Masami Hiramatsu (Google) <[email protected]>
