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")
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
