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

Masami Hiramatsu
2020-08-28T12:26:48Z

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@kernel.org>