Re: [GIT PULL] tracing/kprobes: Add dynamic tracepoints + instruction decoder

[Masami Hiramatsu <mhiramat@redhat.com>]

Frederic Weisbecker wrote:
> Ingo,
> 
> This is the kprobes tracing pile of patches. I've tested it
> successfully by setting some kprobes through debugfs by hand.
> 
> It brings no known regressions.
> 
> However, the stress test provided by Masami have revealed some
> unstable points. Some symbols are unsafe to probe and raise
> probing recursion.
> 
> I've added a tiny patch in the series that helps identifying the
> kprobe that has raised such situation.
> For example it has learned me today that it's unsafe to trace
> ret_from_exception() (obviously: it's on the int 3 handler path).

Thank you, Frederic.

I'm currently fixing those problems on x86-64 (on kvm).
I'll also check it on x86-32, and fix it.

Thanks

> Anyway, we have all the tools to debug that and easily find the
> fragile points to probe. It's then just a matter of investigation
> and stress tests now.
> 
> And because the pile of patches becomes big enough, I've thought it
> could be time to do a pull request for -tip for it to have a
> private branch and get fixes over the time.
> 
> Tell me if that's a problem and we can delay the pull request until
> we fix the recursive points problems.
> 
> Thanks,
> Frederic.
> 
> The following changes since commit 35dce1a99d010f3d738af4ce1b9b77302fdfe69c:
>    Ingo Molnar (1):
>          Merge branch 'tracing/core' of git://git.kernel.org/.../frederic/random-tracing into tracing/core
> 
> are available in the git repository at:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing.git
> 	tracing/kprobes
> 
> Frederic Weisbecker (1):
>        tracing/kprobes: Dump the culprit kprobe in case of kprobe recursion
> 
> Masami Hiramatsu (17):
>        x86: Instruction decoder API
>        x86: X86 instruction decoder build-time selftest
>        kprobes: Checks probe address is instruction boudary on x86
>        kprobes: Cleanup fix_riprel() using insn decoder on x86
>        x86: Add pt_regs register and stack access APIs
>        tracing: Ftrace dynamic ftrace_event_call support
>        tracing: Introduce TRACE_FIELD_ZERO() macro
>        tracing: Add kprobe-based event tracer
>        tracing: Add kprobe-based event tracer documentation
>        tracing: Kprobe-tracer supports more than 6 arguments
>        tracing: Generate names for each kprobe event automatically
>        tracing: Kprobe tracer assigns new event ids for each event
>        tracing: Add kprobes event profiling interface
>        x86: Fix x86 instruction decoder selftest to check only .text
>        x86: Check awk features before generating inat-tables.c
>        tracing/kprobes: Fix format typo in trace_kprobes
>        tracing/kprobes: Change trace_arg to probe_arg
> 
>   Documentation/trace/kprobetrace.txt  |  148 ++++
>   arch/x86/Kconfig.debug               |    9 +
>   arch/x86/Makefile                    |    3 +
>   arch/x86/include/asm/inat.h          |  188 ++++++
>   arch/x86/include/asm/inat_types.h    |   29 +
>   arch/x86/include/asm/insn.h          |  143 ++++
>   arch/x86/include/asm/ptrace.h        |   62 ++
>   arch/x86/kernel/kprobes.c            |  209 +++---
>   arch/x86/kernel/ptrace.c             |  112 +++
>   arch/x86/lib/Makefile                |   13 +
>   arch/x86/lib/inat.c                  |   78 +++
>   arch/x86/lib/insn.c                  |  464 +++++++++++++
>   arch/x86/lib/x86-opcode-map.txt      |  719 ++++++++++++++++++++
>   arch/x86/tools/Makefile              |   15 +
>   arch/x86/tools/distill.awk           |   42 ++
>   arch/x86/tools/gen-insn-attr-x86.awk |  334 +++++++++
>   arch/x86/tools/test_get_len.c        |  113 ++++
>   include/linux/ftrace_event.h         |   19 +-
>   include/linux/kprobes.h              |    2 +
>   include/linux/syscalls.h             |    4 +-
>   include/trace/ftrace.h               |   16 +-
>   include/trace/syscall.h              |   11 +-
>   kernel/kprobes.c                     |    7 +
>   kernel/trace/Kconfig                 |   12 +
>   kernel/trace/Makefile                |    1 +
>   kernel/trace/trace.h                 |   24 +
>   kernel/trace/trace_event_types.h     |    4 +-
>   kernel/trace/trace_events.c          |  121 +++-
>   kernel/trace/trace_export.c          |   34 +-
>   kernel/trace/trace_kprobe.c          | 1231 ++++++++++++++++++++++++++++++++++
>   kernel/trace/trace_syscalls.c        |   20 +-
>   31 files changed, 3991 insertions(+), 196 deletions(-)
>   create mode 100644 Documentation/trace/kprobetrace.txt
>   create mode 100644 arch/x86/include/asm/inat.h
>   create mode 100644 arch/x86/include/asm/inat_types.h
>   create mode 100644 arch/x86/include/asm/insn.h
>   create mode 100644 arch/x86/lib/inat.c
>   create mode 100644 arch/x86/lib/insn.c
>   create mode 100644 arch/x86/lib/x86-opcode-map.txt
>   create mode 100644 arch/x86/tools/Makefile
>   create mode 100644 arch/x86/tools/distill.awk
>   create mode 100644 arch/x86/tools/gen-insn-attr-x86.awk
>   create mode 100644 arch/x86/tools/test_get_len.c
>   create mode 100644 kernel/trace/trace_kprobe.c

-- 
Masami Hiramatsu

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

e-mail: mhiramat@redhat.com