[RFC PATCH -tip v5 00/27] kprobes: Cleanup jprobe implementation

[Masami Hiramatsu <mhiramat@kernel.org>]

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 5th version of the series for removing jprobe.
Previous version is here:

 https://lkml.org/lkml/2018/5/28/71

In this version, I just fixed [24/27] patch to remove unneeded
preempt_disable/enabel and cleanup current_kprobe in
kprobe_ftrace_handler on arch/powerpc too.
Also, I added arch-specific mailing lists to Cc but optimize
Cc list for each patch. So only arch related patches are sent
to each mailing list.

BTW, in the previous version I missed RFC on the patch tag...
This time I added it.

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
      kprobes/x86: 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           |   46 ++------
 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, 131 insertions(+), 1315 deletions(-)
 delete mode 100644 arch/ia64/kernel/jprobes.S

--
Masami Hiramatsu (Linaro)