On Wed, 1 Jul 2026 12:14:54 +0000 Pu Hu <[email protected]> wrote: > From: hupu <[email protected]> > > This series fixes two arm64 kprobes issues observed when running > simpleperf with preemptirq tracepoints and dwarf callchains while a > kprobe is active on a frequently executed kernel function. > > The crash happens in the kprobe debug exception path. While a kprobe is > preparing or executing its XOL single-step instruction, perf/trace code > can run in the same window. That code may either take a fault of its own > or hit another kprobe. > > Patch 1 makes kprobe_fault_handler() handle a fault in > KPROBE_HIT_SS/KPROBE_REENTER only when the faulting PC points at the > current kprobe's XOL instruction. Otherwise the fault is left to the > normal fault handling path. > > Patch 2 allows a kprobe hit in KPROBE_HIT_SS to be handled as a > recoverable one-level reentry. Only a hit while already in > KPROBE_REENTER remains unrecoverable. > > This follows the same logic as the existing x86 fixes: > 6381c24cd6d5 ("kprobes/x86: Fix page-fault handling logic") > 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on > single-stepping")
Good catch!! The series looks good to me. Acked-by: Masami Hiramatsu (Google) <[email protected]> But it should be reviewed by arm64 maintainers too. BTW, if you are "Pu Hu", the Signed-off-by tag should be "Pu Hu <...>" instead of "hupu <...>". Thank you, > > Reproducer: > > simpleperf record -p <pid> -f 10000 \ > -e preemptirq:preempt_disable \ > -e preemptirq:preempt_enable \ > --duration 9 --call-graph dwarf \ > -o /data/local/tmp/perf.data > > Before this series, the crash reproduced frequently. With both patches > applied, it was no longer reproduced in our testing. > > hupu (2): > arm64: kprobes: Do not handle non-XOL faults as kprobe faults > arm64: kprobes: Allow reentering kprobes while single-stepping > > arch/arm64/kernel/probes/kprobes.c | 22 +++++++++++++++++++++- > 1 file changed, 21 insertions(+), 1 deletion(-) > > -- > 2.43.0 > > -- Masami Hiramatsu (Google) <[email protected]>
