Oops, the title version is wrong, this is 8th version. Hmm, it must be my typo... On Tue, 2 May 2023 00:08:45 +0900 "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote: > Hi, > > Here is the 8th version of improve fprobe and add a basic fprobe event > support for ftrace (tracefs) and perf. Here is the previous version. > > https://lore.kernel.org/all/168255826500.2565678.17719875734305974633.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > > This version is a minor update for fixing wrong indentation [8/11] > and update kconfig help message[6/11]. > > You can also get this series from: > > git://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git topic/fprobe-event-ext > > With this fprobe events, we can continue to trace function entry/exit > even if the CONFIG_KPROBES_ON_FTRACE is not available. Since > CONFIG_KPROBES_ON_FTRACE requires the CONFIG_DYNAMIC_FTRACE_WITH_REGS, > it is not available if the architecture only supports > CONFIG_DYNAMIC_FTRACE_WITH_ARGS (e.g. arm64). And that means kprobe > events can not probe function entry/exit effectively on such architecture. > But this problem can be solved if the dynamic events supports fprobe events > because fprobe events doesn't use kprobe but ftrace via fprobe. > > FPROBE EVENTS > ============= > > Fprobe events allows user to add new events on the entry and exit of kernel > functions (which can be ftraced). Unlike kprobe events, the fprobe events > can only probe the function entry and exit, and it can only trace the > function args, return value, and stacks. (no registers) > For probing function body, users can continue to use the kprobe events. > > The tracepoint probe events (tprobe events) also allows user to add new > events dynamically on the tracepoint. Most of the tracepoint already has > trace-events, so this feature is useful if you only want to know a > specific parameter, or trace the tracepoints which has no trace-events > (e.g. sched_*_tp tracepoints only exposes the tracepoints.) > > The fprobe events syntax is; > > f[:[GRP/][EVENT]] FUNCTION [FETCHARGS] > f[MAXACTIVE][:[GRP/][EVENT]] FUNCTION%return [FETCHARGS] > > And tracepoint probe events syntax is; > > t[:[GRP/][EVENT]] TRACEPOINT [FETCHARGS] > > This series includes BTF argument support for fprobe/tracepoint events, > and kprobe events. This allows us to fetch a specific function parameter > by name, and all parameters by '$$args'. > Note that enabling this feature, you need to enable CONFIG_BPF_SYSCALL and > confirm that your arch supports CONFIG_HAVE_FUNCTION_ARG_ACCESS_API. > > E.g. > > # echo 't kfree ptr' >> dynamic_events > # echo 'f kfree object' >> dynamic_events > # cat dynamic_events > t:tracepoints/kfree kfree ptr=ptr > f:fprobes/kfree__entry kfree object=object > # echo 1 > events/fprobes/enable > # echo 1 > events/tracepoints/enable > # echo > trace > # head -n 20 trace | tail > # TASK-PID CPU# ||||| TIMESTAMP FUNCTION > # | | | ||||| | | > tail-84 [000] ..... 1324.561958: kfree__entry: (kfree+0x4/0x140) object=0xffff888006383c00 > tail-84 [000] ...1. 1324.561961: kfree: (__probestub_kfree+0x4/0x10) ptr=0xffff888006383c00 > tail-84 [000] ..... 1324.561988: kfree__entry: (kfree+0x4/0x140) object=0x0 > tail-84 [000] ...1. 1324.561988: kfree: (__probestub_kfree+0x4/0x10) ptr=0x0 > tail-84 [000] ..... 1324.561989: kfree__entry: (kfree+0x4/0x140) object=0xffff88800671e600 > tail-84 [000] ...1. 1324.561989: kfree: (__probestub_kfree+0x4/0x10) ptr=0xffff88800671e600 > tail-84 [000] ..... 1324.562368: kfree__entry: (kfree+0x4/0x140) object=0xffff8880065e0580 > tail-84 [000] ...1. 1324.562369: kfree: (__probestub_kfree+0x4/0x10) ptr=0xffff8880065e0580 > > > Thank you, > > --- > > Masami Hiramatsu (Google) (11): > fprobe: Pass return address to the handlers > tracing/probes: Add fprobe events for tracing function entry and exit. > selftests/ftrace: Add fprobe related testcases > tracing/probes: Add tracepoint support on fprobe_events > tracing/probes: Move event parameter fetching code to common parser > tracing/probes: Support function parameters if BTF is available > tracing/probes: Add $$args meta argument for all function args > tracing/probes: Add BTF retval type support > selftests/ftrace: Add tracepoint probe test case > selftests/ftrace: Add BTF arguments test cases > Documentation: tracing/probes: Add fprobe event tracing document > > > Documentation/trace/fprobetrace.rst | 187 +++ > Documentation/trace/index.rst | 1 > include/linux/fprobe.h | 11 > include/linux/rethook.h | 2 > include/linux/trace_events.h | 3 > include/linux/tracepoint-defs.h | 1 > include/linux/tracepoint.h | 5 > kernel/kprobes.c | 1 > kernel/trace/Kconfig | 26 > kernel/trace/Makefile | 1 > kernel/trace/bpf_trace.c | 6 > kernel/trace/fprobe.c | 17 > kernel/trace/rethook.c | 3 > kernel/trace/trace.c | 13 > kernel/trace/trace.h | 11 > kernel/trace/trace_eprobe.c | 44 - > kernel/trace/trace_fprobe.c | 1194 ++++++++++++++++++++ > kernel/trace/trace_kprobe.c | 33 - > kernel/trace/trace_probe.c | 504 +++++++- > kernel/trace/trace_probe.h | 43 + > kernel/trace/trace_uprobe.c | 8 > lib/test_fprobe.c | 10 > samples/fprobe/fprobe_example.c | 6 > .../ftrace/test.d/dynevent/add_remove_btfarg.tc | 54 + > .../ftrace/test.d/dynevent/add_remove_fprobe.tc | 26 > .../ftrace/test.d/dynevent/add_remove_tprobe.tc | 27 > .../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 99 ++ > .../ftrace/test.d/dynevent/tprobe_syntax_errors.tc | 82 + > .../ftrace/test.d/kprobe/kprobe_syntax_errors.tc | 13 > 29 files changed, 2291 insertions(+), 140 deletions(-) > create mode 100644 Documentation/trace/fprobetrace.rst > create mode 100644 kernel/trace/trace_fprobe.c > create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_btfarg.tc > create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe.tc > create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_tprobe.tc > create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc > create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/tprobe_syntax_errors.tc > > -- > Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> -- Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
