linux-kernel - [PATCH v4 00/23] kprobes: Unify kretprobe trampoline handlers and make kretprobe lockless

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Date:   Fri, 28 Aug 2020 21:26:38 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     linux-kernel@...r.kernel.org, Peter Zijlstra <peterz@...radead.org>
Cc:     Eddy_Wu@...ndmicro.com, x86@...nel.org, davem@...emloft.net,
        rostedt@...dmis.org, naveen.n.rao@...ux.ibm.com,
        anil.s.keshavamurthy@...el.com, linux-arch@...r.kernel.org,
        cameron@...dycamel.com, oleg@...hat.com, will@...nel.org,
        paulmck@...nel.org, mhiramat@...nel.org
Subject: [PATCH v4 00/23] kprobes: Unify kretprobe trampoline handlers and make kretprobe lockless

Hi,

Here is the 4th version of the series to unify the kretprobe trampoline handler
and make kretprobe lockless.

Previous version is here;

 https://lkml.kernel.org/r/159854631442.736475.5062989489155389472.stgit@devnote2

In this version, I updated the generic trampoline handler a bit, merge 
the Peter's lockless patches(*), and add an RFC "remove task scan" patch
as [20/23].

(*) https://lkml.kernel.org/r/20200827161237.889877377@infradead.org

I ran some tests and ftracetest on x86-64. Mostly OK, but hit a BUG in the
trampoline handler once. I'm trying to reproduce it but not succeeded yet.
So this may need a careful review and tests.

I did something like:

mount -t debugfs debug /sys/kernel/debug
cd /sys/kernel/debug/tracing/
echo r:event1 vfs_read >> kprobe_events
echo r:event2 vfs_read %ax >> kprobe_events
echo r:event3 rw_verify_area %ax >> kprobe_events
echo 1 > events/kprobes/enable
sleep 1
less trace
cat ../kprobes/list
cd ~/linux/tools/testing/selftests/ftrace
./ftracetest

Then hits a BUG_ON at kernel/kprobes.c:1893 (no test executed, maybe
it happened when removing kretprobes?)

Thank you,

---

Masami Hiramatsu (17):
      kprobes: Add generic kretprobe trampoline handler
      x86/kprobes: Use generic kretprobe trampoline handler
      arm: kprobes: Use generic kretprobe trampoline handler
      arm64: kprobes: Use generic kretprobe trampoline handler
      arc: kprobes: Use generic kretprobe trampoline handler
      csky: kprobes: Use generic kretprobe trampoline handler
      ia64: kprobes: Use generic kretprobe trampoline handler
      mips: kprobes: Use generic kretprobe trampoline handler
      parisc: kprobes: Use generic kretprobe trampoline handler
      powerpc: kprobes: Use generic kretprobe trampoline handler
      s390: kprobes: Use generic kretprobe trampoline handler
      sh: kprobes: Use generic kretprobe trampoline handler
      sparc: kprobes: Use generic kretprobe trampoline handler
      kprobes: Remove NMI context check
      kprobes: Free kretprobe_instance with rcu callback
      kprobes: Make local used functions static
      [RFC] kprobes: Remove task scan for updating kretprobe_instance

Peter Zijlstra (6):
      llist: Add nonatomic __llist_add()
      sched: Fix try_invoke_on_locked_down_task() semantics
      kprobes: Remove kretprobe hash
      asm-generic/atomic: Add try_cmpxchg() fallbacks
      freelist: Lock less freelist
      kprobes: Replace rp->free_instance with freelist


 arch/arc/kernel/kprobes.c                 |   54 ------
 arch/arm/probes/kprobes/core.c            |   78 ---------
 arch/arm64/kernel/probes/kprobes.c        |   78 ---------
 arch/csky/kernel/probes/kprobes.c         |   77 --------
 arch/ia64/kernel/kprobes.c                |   77 --------
 arch/mips/kernel/kprobes.c                |   54 ------
 arch/parisc/kernel/kprobes.c              |   76 --------
 arch/powerpc/kernel/kprobes.c             |   53 ------
 arch/s390/kernel/kprobes.c                |   79 ---------
 arch/sh/kernel/kprobes.c                  |   58 ------
 arch/sparc/kernel/kprobes.c               |   51 ------
 arch/x86/include/asm/atomic.h             |    2 
 arch/x86/include/asm/atomic64_64.h        |    2 
 arch/x86/include/asm/cmpxchg.h            |    2 
 arch/x86/kernel/kprobes/core.c            |  108 ------------
 drivers/gpu/drm/i915/i915_request.c       |    6 -
 include/asm-generic/atomic-instrumented.h |  216 ++++++++++++++----------
 include/linux/atomic-arch-fallback.h      |   90 +++++++++-
 include/linux/atomic-fallback.h           |   90 +++++++++-
 include/linux/freelist.h                  |  129 ++++++++++++++
 include/linux/kprobes.h                   |   73 +++++---
 include/linux/llist.h                     |   15 ++
 include/linux/sched.h                     |    4 
 kernel/fork.c                             |    4 
 kernel/kprobes.c                          |  263 +++++++++++++----------------
 kernel/sched/core.c                       |    9 -
 kernel/trace/trace_kprobe.c               |    3 
 scripts/atomic/gen-atomic-fallback.sh     |   63 ++++++-
 scripts/atomic/gen-atomic-instrumented.sh |   29 +++
 29 files changed, 729 insertions(+), 1114 deletions(-)
 create mode 100644 include/linux/freelist.h

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