On Tue, 23 Jun 2026 10:44:10 +0900 "Masami Hiramatsu (Google)" <[email protected]> wrote:
> 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. I'll take the first 2 patches to probes/core, since those are obvious fix and cleanup. Thanks, > > 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) <[email protected]> -- Masami Hiramatsu (Google) <[email protected]>
