| From f3fbd7ec62dec1528fb8044034e2885f2b257941 Mon Sep 17 00:00:00 2001 |
| From: Masami Hiramatsu <mhiramat@kernel.org> |
| Date: Tue, 14 Feb 2017 00:03:38 +0900 |
| Subject: arm: kprobes: Allow to handle reentered kprobe on single-stepping |
| |
| 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(); |