linux-kernel - [PATCH v2 0/3] perf probe: Introduce remote cross-arch probes

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Message-Id: <147214224523.23638.10155676067678947950.stgit@devbox>
Date:   Fri, 26 Aug 2016 01:24:10 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...hat.com>
Subject: [PATCH v2 0/3] perf probe: Introduce remote cross-arch probes

Hi,

Here is the 2nd version of remote cross-arch probe support on perf-probe.
V1 is here:
  https://lkml.org/lkml/2016/8/24/29

Currently perf-probe doesn't supoort cross/remote target. This means
we have to cross-build the perf-tools including libraries (elfutils,
libelf etc.), and to prepare vmlinux with debuginfo which can be 
accessed from the target machine.
This requires too much resource for a small embededd device.

If we can analyze the debuginfo by perf-probe on host machine,
we do not need to cross-build perf-tools, nor copy vmlinux on the
device. :)

For that purpose, this series adds --definition(-D) command for
perf-probe, which shows trace event definition instead of adding
it in running kernel, according to Arnaldo's comment.
Using -D with --vmlinux(or -k)=OFFLINE-VMLINUX, perf-probe reads
the vmlinux architecture and show definition with correct
dwarf-registers.

  perf probe -k <cross-vmlinux> -D <probe-point> <arguments>

Here is an example:
  -----
  $ perf probe --vmlinux=./vmlinux-arm --definition 'do_sys_open $params'
  p:probe/do_sys_open do_sys_open+0 dfd=%r5:s32 filename=%r1:u32 flags=%r6:s32 mode=%r3:u16
  -----
Here, we can get probe/do_sys_open event by "copy & paste" the
definition to target-machine's debugfs/tracing/kprobe_events.

Note that it shows definition with direct symbol name instead of
_text+offset. It is treated as an offline module.

Thanks,
---

Masami Hiramatsu (3):
      perf-probe: Show trace event definition
      perf-probe: Ignore vmlinux buildid if offline kernel is given
      perf-probe: Support probing on offline cross-arch binary


 tools/perf/Documentation/perf-probe.txt            |    9 +++
 tools/perf/arch/arm/include/dwarf-regs-table.h     |    9 +++
 tools/perf/arch/arm64/include/dwarf-regs-table.h   |   13 +++++
 tools/perf/arch/powerpc/include/dwarf-regs-table.h |   27 ++++++++++
 tools/perf/arch/s390/include/dwarf-regs-table.h    |    8 +++
 tools/perf/arch/sh/include/dwarf-regs-table.h      |   25 +++++++++
 tools/perf/arch/sparc/include/dwarf-regs-table.h   |   18 +++++++
 tools/perf/arch/x86/include/dwarf-regs-table.h     |   14 +++++
 tools/perf/arch/xtensa/include/dwarf-regs-table.h  |    8 +++
 tools/perf/builtin-probe.c                         |   34 ++++++++++--
 tools/perf/util/Build                              |    1 
 tools/perf/util/dwarf-regs.c                       |   55 ++++++++++++++++++++
 tools/perf/util/include/dwarf-regs.h               |    6 ++
 tools/perf/util/probe-event.c                      |   50 ++++++++++++++++++
 tools/perf/util/probe-event.h                      |    1 
 tools/perf/util/probe-finder.c                     |   27 ++++++----
 tools/perf/util/probe-finder.h                     |    1 
 tools/perf/util/symbol-elf.c                       |    2 -
 18 files changed, 289 insertions(+), 19 deletions(-)
 create mode 100644 tools/perf/arch/arm/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/arm64/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/powerpc/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/s390/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/sh/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/sparc/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/x86/include/dwarf-regs-table.h
 create mode 100644 tools/perf/arch/xtensa/include/dwarf-regs-table.h
 create mode 100644 tools/perf/util/dwarf-regs.c

--
Masami Hiramatsu (Linaro Ltd.) <mhiramat@...nel.org>