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Subject[PATCH tracing/kprobes v2 0/5] tracing/kprobes, perf: perf probe support take 2
Date
Hi,

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

This version fixes some bugs, changes subcommand name from kprobe to
probe and use spaces for separator instead of ',' for visibility (this
also make it easy to support probe list from stdin).

Usage
-----
perf probe [<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 ...]>
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 probe -P 'p:myprobe @fs/read_write.c:285 file buf count'
Adding new event: p:myprobe vfs_read+57 file=%bx buf=%si count=%ax
2) Add a new kretprobe probe on a function return.
./perf probe -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) Record the event by perf
./perf record -f -e kprobes:myprobe:record -F 1 -a ls
...
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.081 MB perf.data (~3540 samples) ]

5) Trace the event
./perf trace
perf-11445 [000] 95862.048894383: myprobe: (c04bbed5) file=dae15e80 buf=b78b2000 count=400
perf-11445 [000] 95862.049066533: myprobe: (c04bbed5) file=dae15d80 buf=b78b2000 count=400
perf-11445 [000] 95862.049134394: myprobe: (c04bbed5) file=dae15d80 buf=b78b2000 count=400
perf-11445 [000] 95862.049171495: myprobe: (c04bbed5) file=dae15a80 buf=b78b2000 count=400

NOTE
----
perf still fails to parse format if arguments have special charactors
(e.g. $rv, +10($sp) etc.) So, tracing myretprobe will fail with this
version. This will be solved by naming arguments automatically if it
doesn't have C-language name.
TODO
----
- Support sys_perf_counter_open (non-root)
- Input from stdin/output to stdout
- Non-auto static variable
- Fields of data structures (var->field)
- Type support
- 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
- etc.
Thank you,

---
Masami Hiramatsu (5):
perf: kprobe command supports without libdwarf
perf: Add perf probe subcommand 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 | 125 +++++-
tools/perf/Makefile | 10 +
tools/perf/builtin-probe.c | 384 +++++++++++++++++++
tools/perf/builtin.h | 1
tools/perf/perf.c | 1
tools/perf/util/probe-finder.c | 690 +++++++++++++++++++++++++++++++++++
tools/perf/util/probe-finder.h | 70 ++++
8 files changed, 1251 insertions(+), 40 deletions(-)
create mode 100644 tools/perf/builtin-probe.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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