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Subject[PATCH tracing/kprobes v3 0/7] tracing/kprobes, perf: perf probe support take 3
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, remove -r option (because perf always be
used for online kernel) and rename kprobe-tracer special vars.

Usage
-----
perf probe [<options>] -P 'PROBEDEF' [-P 'PROBEDEF' ...]

-k, --vmlinux <file> vmlinux/module pathname
-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 $retval'
Adding new event: r:myretprobe vfs_read+0 $retval

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. $retval, +16($stack) 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
- 64-bits return value on x86-32
- 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 (7):
perf: perf probe 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
tracing/kprobes: Remove '$ra' special variable
tracing/kprobes: Add $ prefix to special variables


Documentation/trace/kprobetrace.txt | 27 +
kernel/trace/trace_kprobe.c | 158 +++++---
tools/perf/Makefile | 10 +
tools/perf/builtin-probe.c | 385 ++++++++++++++++++++
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, 1269 insertions(+), 73 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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