From: Masami Hiramatsu mhiramat@kernel.org
commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream.
This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on single-stepping")
Since the FIQ handlers can interrupt in the single stepping (or preparing the single stepping, do_debug etc.), we should consider a kprobe is hit in the NMI handler. Even in that case, the kprobe is allowed to be reentered as same as the kprobes hit in kprobe handlers (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE).
The real issue will happen when a kprobe hit while another reentered kprobe is processing (KPROBE_REENTER), because we already consumed a saved-area for the previous kprobe.
Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Signed-off-by: Jon Medhurst tixy@linaro.org Fixes: 24ba613c9d6c ("ARM kprobes: core code") Cc: stable@vger.kernel.org #v2.6.25~v4.11 Signed-off-by: huangshaobo huangshaobo6@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm/probes/kprobes/core.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -270,6 +270,7 @@ void __kprobes kprobe_handler(struct pt_ switch (kcb->kprobe_status) { case KPROBE_HIT_ACTIVE: case KPROBE_HIT_SSDONE: + case KPROBE_HIT_SS: /* A pre- or post-handler probe got us here. */ kprobes_inc_nmissed_count(p); save_previous_kprobe(kcb); @@ -278,6 +279,11 @@ void __kprobes kprobe_handler(struct pt_ singlestep(p, regs, kcb); restore_previous_kprobe(kcb); break; + case KPROBE_REENTER: + /* A nested probe was hit in FIQ, it is a BUG */ + pr_warn("Unrecoverable kprobe detected at %p.\n", + p->addr); + /* fall through */ default: /* impossible cases */ BUG();