Re: [PATCH -tip v4 00/27] kprobes: Cleanup jprobe implementation

[Masami Hiramatsu]

Hi Naveen,

Sorry, I might miss to add you on CC list. Could you test and review this on powerpc?

Thank you,

On Mon, 28 May 2018 15:59:09 +0900
Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> Hello,
> 
> Since we decided to remove jprobe from kernel last year,
> its APIs are disabled and we worked on moving in-kernel
> jprobe users to kprobes or trace-events. And now no jprobe
> users are here anymore.
> 
> This is the 4th version of the series for removing jprobe.
> Previous version is here:
> 
>  https://lkml.org/lkml/2018/5/16/1052
> 
> Unlike previous versions, this version removes jprobe from
> all architectures, as Ingo asked me in the previous thread.
> 
> I marked this as RFC again because it introduced changes for
> many arch. It should be reviewed by some arch which is not
> simply removing code (e.g. powerpc, arm).
> 
> BTW, this series are based on -tip tree as same as its
> previous version, and I'm sure it can be applied to
> linus tree/linux-next too.
> 
> Series structure
> =====
> Basically this series introduces 3 major changes;
> 
> - Remove jprobe implementation ([2/27] - [12/27])
> 
> - Remove break_handler() related code ([13/27] - [23/27])
>   This should be done after (or with) removing jprobe
>   because break_handler is only used by jprobe.
>  (I'm not so sure, should I merge above patches into one
>   arch-wide patch as next one does?)
> 
> - Clean current_kprobe and enable preempt if pre_handler()
>   returns !0 ([24/27] and [25/27]<- x86 specific update)
>   This also depends on above patches because those
>   current_kprobe and preemption are expected to be adjusted
>   by jprobe implementation via break_handler.
> 
> And some minor changes;
> 
> - Document cleanup and update ([1/27], [26/27])
> 
> And finally remove jprobe stub APIs and break_handler
> from kprobes.h ([27/27]). Of course this depends on
> above patches.
> 
> Since removing jprobes and break_handler related code
> involve archtecture specific changes in some archs,
> I splitted it for each arch. But "clean current_kprobe and
> enable preempt if pre_handler() returns !0" patch modifies
> all architectures, since it changes expected kprobe
> handler behavior. I think this would be better done in
> one patch for consistency.
> 
> Result
> =====
> I've tested it with kprobe sanity test on x86-64, and arm64
> but for other archs, I just did cross-build test.
> 
> With this series, we finally cleanup all jprobe code
> and break_handler as below.
> 
> $ git grep -wi break_handler | wc -l
> 0
> $ git grep -wi jprobe | wc -l
> 0
> 
> Actually, there is one place where mentioning jprobe,
> Documentation/kprobes.txt explains jprobe is deprecated
> and how to migrate jprobe user to ftrace or kprobe.
> I didn't remove it because it might be useful for
> some users.
> 
> Thank you,
> 
> ---
> 
> Masami Hiramatsu (27):
>       Documentation/kprobes: Fix to remove remaining jprobe
>       kprobes: Remove jprobe API implementation
>       kprobes/x86: Remove jprobe implementation
>       ARC: kprobes: Remove jprobe implementation
>       ARM: kprobes: Remove jprobe arm implementation
>       arm64: kprobes: Remove jprobe implementation
>       powerpc/kprobes: Remove jprobe powerpc implementation
>       ia64: kprobes: Remove jprobe implementation
>       MIPS: kprobes: Remove jprobe implementation
>       s390/kprobes: Remove jprobe implementation
>       sh: kprobes: Remove jprobe implementation
>       sparc64: kprobes: Remove jprobe implementation
>       kprobes: Don't check the ->break_handler() in generic kprobes code
>       kprobes/x86: Don't call ->break_handler() in x86 kprobes
>       ARC: kprobes: Don't call the ->break_handler() in ARC kprobes code
>       ARM: kprobes: Don't call the ->break_handler() in arm kprobes code
>       arm64: kprobes: Don't call the ->break_handler() in arm kprobes code
>       powerpc/kprobes: Don't call the ->break_handler() in arm kprobes code
>       ia64: kprobes: Don't call the ->break_handler() in ia64 kprobes code
>       MIPS: kprobes: Don't call the ->break_handler() in MIPS kprobes code
>       s390/kprobes: Don't call the ->break_handler() in s390 kprobes code
>       sh: kprobes: Don't call the ->break_handler() in SH kprobes code
>       sparc64: kprobes: Don't call the ->break_handler() in sparc64 kprobes code
>       bpf: error-inject: kprobes: Clear current_kprobe and enable preempt in kprobe
>       x86: kprobes: Do not disable preempt on int3 path
>       Documentation: kprobes: Add how to change the execution path
>       kprobes: Remove jprobe stub API
> 
> 
>  Documentation/kprobes.txt                      |   35 +++++-
>  arch/arc/include/asm/kprobes.h                 |    2 
>  arch/arc/kernel/kprobes.c                      |   50 +--------
>  arch/arm/include/asm/kprobes.h                 |    2 
>  arch/arm/include/asm/probes.h                  |    1 
>  arch/arm/probes/kprobes/core.c                 |  135 +-----------------------
>  arch/arm64/include/asm/kprobes.h               |    1 
>  arch/arm64/kernel/probes/kprobes.c             |   86 +--------------
>  arch/ia64/include/asm/kprobes.h                |    2 
>  arch/ia64/include/uapi/asm/break.h             |    1 
>  arch/ia64/kernel/Makefile                      |    2 
>  arch/ia64/kernel/jprobes.S                     |   90 ----------------
>  arch/ia64/kernel/kprobes.c                     |   93 +----------------
>  arch/mips/include/asm/kprobes.h                |   13 --
>  arch/mips/kernel/kprobes.c                     |   70 ++----------
>  arch/powerpc/include/asm/kprobes.h             |   12 --
>  arch/powerpc/kernel/kprobes-ftrace.c           |   31 +-----
>  arch/powerpc/kernel/kprobes.c                  |   92 +++-------------
>  arch/powerpc/kernel/trace/ftrace_64_mprofile.S |   39 +------
>  arch/s390/include/asm/kprobes.h                |    2 
>  arch/s390/kernel/kprobes.c                     |   86 +--------------
>  arch/sh/include/asm/kprobes.h                  |    4 -
>  arch/sh/kernel/kprobes.c                       |   72 +------------
>  arch/sparc/include/asm/kprobes.h               |    1 
>  arch/sparc/kernel/kprobes.c                    |   65 +-----------
>  arch/x86/include/asm/kprobes.h                 |    5 -
>  arch/x86/kernel/kprobes/common.h               |   10 --
>  arch/x86/kernel/kprobes/core.c                 |  119 +--------------------
>  arch/x86/kernel/kprobes/ftrace.c               |   31 ++----
>  arch/x86/kernel/kprobes/opt.c                  |    1 
>  include/linux/kprobes.h                        |   53 ---------
>  kernel/fail_function.c                         |    3 -
>  kernel/kprobes.c                               |  115 +-------------------
>  kernel/test_kprobes.c                          |   94 -----------------
>  kernel/trace/trace_kprobe.c                    |   11 +-
>  lib/Kconfig.debug                              |    2 
>  36 files changed, 125 insertions(+), 1306 deletions(-)
>  delete mode 100644 arch/ia64/kernel/jprobes.S
> 
> --
> Masami Hiramatsu (Linaro)


-- 
Masami Hiramatsu <mhiramat@xxxxxxxxxx>