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    Subject[RFC PATCH tracing/kprobes 0/5] tracing/kprobes, perf: perf kprobe support
    Date

    Hi,

    These patches introduce perf kprobe command and update kprobe-tracer.
    perf kprobe command allows you to add new probe points by C line number
    and local variable names.

    Usage
    -----
    perf kprobe [<options>] -P PROBEDEF [-P PROBEDEF ...]

    -k, --vmlinux <file> vmlinux/module pathname
    -r, --release <rel> kernel release
    -P, --probe <p|r:[GRP/]NAME,FUNC[+OFFS][@SRC]|@SRC:LINE,ARG[,ARG,...]>
    probe point definition, where
    p: kprobe probe
    r: kretprobe probe
    GRP: Group name (optional)
    NAME: Event name
    FUNC: Function name
    OFFS: Offset from function entry (in byte)
    SRC: Source code path
    LINE: Line number
    ARG: Probe argument (local variable name or
    kprobe-tracer argument format is supported.)

    Examples
    --------
    1) Add a new kprobe probe on a line of C source code.
    ./perf kprobe -P 'p:myprobe,@fs/bio.c:162,bv,idx'
    Adding new event: p:myprobe bvec_free_bs+17 bv=%bx idx=%cx

    2) Add a new kretprobe probe on a function return.
    ./perf kprobe -P 'r:myretprobe,vfs_read,$rv'
    Adding new event: r:myretprobe vfs_read+0 $rv

    3) Check it in the perf list.
    ./perf list
    ...
    rNNN [raw hardware event descriptor]

    kprobes:myprobe [Tracepoint event]
    kprobes:myretprobe [Tracepoint event]
    skb:kfree_skb [Tracepoint event]
    ...

    4) Check its format

    $ cat /sys/kernel/debug/tracing/events/kprobes/myprobe/format
    name: myprobe
    ID: 687
    format:
    field:unsigned short common_type; offset:0; size:2;
    field:unsigned char common_flags; offset:2; size:1;
    field:unsigned char common_preempt_count; offset:3; size:1;
    field:int common_pid; offset:4; size:4;
    field:int common_lock_depth; offset:8; size:4;

    field: unsigned long __probe_ip; offset:12; size:4;
    field: int __probe_nargs; offset:16; size:4;
    field: unsigned long bv; offset:20; size:4;
    field: unsigned long idx; offset:24; size:4;


    print fmt: "(%lx) bv=%lx idx=%lx", REC->__probe_ip, REC->bv, REC->idx


    Syntax Issue
    ------------
    This version picks '-P event-definition' syntax, but I think
    '-p event -a arg' is also possible. I'd like to ask you
    which you like or support both?


    TODO
    ----
    There are still many enhancements required for catching up
    'tracing side' of systemtap. I think it should be done one by one.
    I hope that systemtap developers cooperate with us on this
    development.

    - Support sys_perf_counter_open (non-root)
    - Type support
    - Non-auto static variable
    - Fields of data structure (var->field)
    - Bit fields
    - Array (var[N])
    - Dynamic array indexing (var[var2])
    - String/dynamic arrays (var:string, var[N..M])
    - Force Type casting ((type)var)
    - Non-inline search
    - libdw, libdwfl

    Thank you,

    ---

    Masami Hiramatsu (5):
    perf: kprobe command supports without libdwarf
    perf: Support perf kprobe command for kprobe-event setup helper
    tracing/kprobes: Rename fixed field name
    tracing/kprobes: Avoid field name confliction
    tracing/kprobes: Rename special variables syntax


    Documentation/trace/kprobetrace.txt | 10 -
    kernel/trace/trace_kprobe.c | 124 +++++-
    tools/perf/Makefile | 10 +
    tools/perf/builtin-kprobe.c | 340 +++++++++++++++++
    tools/perf/builtin.h | 1
    tools/perf/perf.c | 1
    tools/perf/util/probe-finder.c | 684 +++++++++++++++++++++++++++++++++++
    tools/perf/util/probe-finder.h | 70 ++++
    8 files changed, 1200 insertions(+), 40 deletions(-)
    create mode 100644 tools/perf/builtin-kprobe.c
    create mode 100644 tools/perf/util/probe-finder.c
    create mode 100644 tools/perf/util/probe-finder.h

    --
    Masami Hiramatsu

    Software Engineer
    Hitachi Computer Products (America), Inc.
    Software Solutions Division

    e-mail: mhiramat@redhat.com


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