On Mon, 23 Oct 2017 22:07:39 +0530
"Naveen N. Rao" <naveen.n....@linux.vnet.ibm.com> wrote:
> Per Documentation/kprobes.txt, we don't necessarily need to disable
> interrupts before invoking the kprobe handlers. Masami submitted
> similar changes for x86 via commit a19b2e3d783964 ("kprobes/x86: Remove
> IRQ disabling from ftrace-based/optimized kprobes"). Do the same for
> powerpc.
Yes, and this requires to make preempt disable :)
Acked-by: Masami Hiramatsu <mhira...@kernel.org>
Thank you!
>
> Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
> ---
> arch/powerpc/kernel/kprobes-ftrace.c | 10 ++--------
> arch/powerpc/kernel/optprobes.c | 10 ----------
> 2 files changed, 2 insertions(+), 18 deletions(-)
>
> diff --git a/arch/powerpc/kernel/kprobes-ftrace.c
> b/arch/powerpc/kernel/kprobes-ftrace.c
> index 4b1f34f685b1..7a1f99f1b47f 100644
> --- a/arch/powerpc/kernel/kprobes-ftrace.c
> +++ b/arch/powerpc/kernel/kprobes-ftrace.c
> @@ -75,11 +75,7 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned
> long parent_nip,
> {
> struct kprobe *p;
> struct kprobe_ctlblk *kcb;
> - unsigned long flags;
>
> - /* Disable irq for emulating a breakpoint and avoiding preempt */
> - local_irq_save(flags);
> - hard_irq_disable();
> preempt_disable();
>
> p = get_kprobe((kprobe_opcode_t *)nip);
> @@ -105,16 +101,14 @@ void kprobe_ftrace_handler(unsigned long nip, unsigned
> long parent_nip,
> else {
> /*
> * If pre_handler returns !0, it sets regs->nip and
> - * resets current kprobe. In this case, we still need
> - * to restore irq, but not preemption.
> + * resets current kprobe. In this case, we should not
> + * re-enable preemption.
> */
> - local_irq_restore(flags);
> return;
> }
> }
> end:
> preempt_enable_no_resched();
> - local_irq_restore(flags);
> }
> NOKPROBE_SYMBOL(kprobe_ftrace_handler);
>
> diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c
> index 60ba7f1370a8..8237884ca389 100644
> --- a/arch/powerpc/kernel/optprobes.c
> +++ b/arch/powerpc/kernel/optprobes.c
> @@ -115,14 +115,10 @@ static unsigned long can_optimize(struct kprobe *p)
> static void optimized_callback(struct optimized_kprobe *op,
> struct pt_regs *regs)
> {
> - unsigned long flags;
> -
> /* This is possible if op is under delayed unoptimizing */
> if (kprobe_disabled(&op->kp))
> return;
>
> - local_irq_save(flags);
> - hard_irq_disable();
> preempt_disable();
>
> if (kprobe_running()) {
> @@ -135,13 +131,7 @@ static void optimized_callback(struct optimized_kprobe
> *op,
> __this_cpu_write(current_kprobe, NULL);
> }
>
> - /*
> - * No need for an explicit __hard_irq_enable() here.
> - * local_irq_restore() will re-enable interrupts,
> - * if they were hard disabled.
> - */
> preempt_enable_no_resched();
> - local_irq_restore(flags);
> }
> NOKPROBE_SYMBOL(optimized_callback);
>
> --
> 2.14.2
>
--
Masami Hiramatsu <mhira...@kernel.org>
