[PATCH 0/4] sparc64: kprobes: Make kprobes work on sun4v

[Stian Halseth <stian@itx.no>]

Any kprobe hit on a sun4v machine oopses, because the probed
instruction is single-stepped from memory that is not executable there.
Patch 1 moves the copy into an instruction slot from get_insn_slot(),
as other architectures do.

Once probes work, three older single-step bugs show up: a taken BPr or
FP branch resumes at the wrong address (patch 2), so does a probe on a
delay slot instruction (patch 3), and an annulled branch can skip the
break instruction after the copy (patch 4).

Tested on a SPARC T7-1 and T4-1 (sun4v) and a Sun Fire V240 (sun4u):
entry and return probes, probes on all 50 instructions of
__task_pid_nr_ns at once while checking getppid(), ps and /proc, probes
on the SPARC AES routines during AF_ALG encryption (sun4v), and refusal
of ba,a. Without the series the first probe hit oopses on sun4v, and a
probe on a taken brnz oopses on sun4u as well.

Stian Halseth (4):
  sparc64: kprobes: Single-step from an executable instruction slot
  sparc64: kprobes: Fix up register and FP branches after single-step
  sparc64: kprobes: Resume after a delay slot at the saved next PC
  sparc64: kprobes: Handle annulled branches

 arch/sparc/include/asm/kprobes.h | 10 +++--
 arch/sparc/kernel/kprobes.c      | 69 +++++++++++++++++++++++++++-----
 2 files changed, 66 insertions(+), 13 deletions(-)


base-commit: af32da41b0327b9c6a37856ba82b6760d6c8d10e
-- 
2.43.0