[v3,0/4] arm64: kprobes: Fix some bugs in arm64 kprobes

Message

Masami Hiramatsu (Google) July 25, 2019, 8:15 a.m. UTC

Hi,

Here are the v3 patches which fixes kprobe bugs on arm64.
In this version I fixed some issues pointed by James and add Reviewed-by
and Acked-bys.

Background:
Naresh reported that recently ftracetest crashes kernel, and I found
there are 3 different bugs around the crash. In v1 thread, we found
one another bug of RCU and debug exception.

- Kprobes on arm64 doesn't recover pstate.D mask after single stepping.
  So after hitting kprobes, the debug flag status is changed.
- Some symbols which are called from blacklisted function, are not
  blacklisted.
- Debug exception is not visible to RCU, thus rcu_read_lock() cause
  a warning inside it.
- Debug exception handlers on arm64 is using rcu_read_lock(), but
  that is not needed because interrupts are disabled.

This series includes fixes for above bugs.

Thank you,

---

Masami Hiramatsu (4):
      arm64: kprobes: Recover pstate.D in single-step exception handler
      arm64: unwind: Prohibit probing on return_address()
      arm64: Make debug exception handlers visible from RCU
      arm64: Remove unneeded rcu_read_lock from debug handlers


 arch/arm64/include/asm/daifflags.h |    2 ++
 arch/arm64/kernel/debug-monitors.c |   14 +++++++------
 arch/arm64/kernel/probes/kprobes.c |   39 +++++------------------------------
 arch/arm64/kernel/return_address.c |    3 +++
 arch/arm64/kernel/stacktrace.c     |    3 +++
 arch/arm64/mm/fault.c              |   40 ++++++++++++++++++++++++++++++++++++
 6 files changed, 61 insertions(+), 40 deletions(-)

--
Masami Hiramatsu (Linaro) <[e-mail]>