| From 8a2d71a3f2737e2448aa68de2b6052cb570d3d2a Mon Sep 17 00:00:00 2001 |
| From: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> |
| Date: Mon, 23 Oct 2017 22:07:38 +0530 |
| Subject: powerpc/kprobes: Disable preemption before invoking probe handler for optprobes |
| |
| From: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> |
| |
| commit 8a2d71a3f2737e2448aa68de2b6052cb570d3d2a upstream. |
| |
| Per Documentation/kprobes.txt, probe handlers need to be invoked with |
| preemption disabled. Update optimized_callback() to do so. Also move |
| get_kprobe_ctlblk() invocation post preemption disable, since it |
| accesses pre-cpu data. |
| |
| This was not an issue so far since optprobes wasn't selected if |
| CONFIG_PREEMPT was enabled. Commit a30b85df7d599f ("kprobes: Use |
| synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y") changes |
| this. |
| |
| Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> |
| Acked-by: Masami Hiramatsu <mhiramat@kernel.org> |
| Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/powerpc/kernel/optprobes.c | 5 +++-- |
| 1 file changed, 3 insertions(+), 2 deletions(-) |
| |
| --- a/arch/powerpc/kernel/optprobes.c |
| +++ b/arch/powerpc/kernel/optprobes.c |
| @@ -115,7 +115,6 @@ static unsigned long can_optimize(struct |
| static void optimized_callback(struct optimized_kprobe *op, |
| struct pt_regs *regs) |
| { |
| - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); |
| unsigned long flags; |
| |
| /* This is possible if op is under delayed unoptimizing */ |
| @@ -124,13 +123,14 @@ static void optimized_callback(struct op |
| |
| local_irq_save(flags); |
| hard_irq_disable(); |
| + preempt_disable(); |
| |
| if (kprobe_running()) { |
| kprobes_inc_nmissed_count(&op->kp); |
| } else { |
| __this_cpu_write(current_kprobe, &op->kp); |
| regs->nip = (unsigned long)op->kp.addr; |
| - kcb->kprobe_status = KPROBE_HIT_ACTIVE; |
| + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; |
| opt_pre_handler(&op->kp, regs); |
| __this_cpu_write(current_kprobe, NULL); |
| } |
| @@ -140,6 +140,7 @@ static void optimized_callback(struct op |
| * local_irq_restore() will re-enable interrupts, |
| * if they were hard disabled. |
| */ |
| + preempt_enable_no_resched(); |
| local_irq_restore(flags); |
| } |
| NOKPROBE_SYMBOL(optimized_callback); |
