Re: [PATCH v3 01/15] uprobes: allow ignoring of probe hits

[Oleg Nesterov <oleg@redhat.com>]

On 11/26, David Long wrote:
>
> From: "David A. Long" <dave.long@linaro.org>
>
> Allow arches to decided to ignore a probe hit.  ARM will use this to
> only call handlers if the conditions to execute a conditionally executed
> instruction are satisfied.
>
> Upleveled for v3.12-rc5.
>
> Signed-off-by: David A. Long <dave.long@linaro.org>

Acked-by: Oleg Nesterov <oleg@redhat.com>


> ---
>  include/linux/uprobes.h | 1 +
>  kernel/events/uprobes.c | 9 +++++++++
>  2 files changed, 10 insertions(+)
> 
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index 319eae7..197a36e 100644
> --- a/include/linux/uprobes.h
> +++ b/include/linux/uprobes.h
> @@ -134,6 +134,7 @@ extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
>  extern int  arch_uprobe_exception_notify(struct notifier_block *self, unsigned long val, void *data);
>  extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs *regs);
>  extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs *regs);
> +extern bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs);
>  #else /* !CONFIG_UPROBES */
>  struct uprobes_state {
>  };
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 24b7d6c..4eec7ce 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1778,6 +1778,11 @@ static bool handle_trampoline(struct pt_regs *regs)
>  	return true;
>  }
>  
> +bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
> +{
> +	return false;
> +}
> +
>  /*
>   * Run handler and ask thread to singlestep.
>   * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
> @@ -1828,7 +1833,11 @@ static void handle_swbp(struct pt_regs *regs)
>  	if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
>  		goto out;
>  
> +	if (arch_uprobe_ignore(&uprobe->arch, regs))
> +		goto out;
> +
>  	handler_chain(uprobe, regs);
> +
>  	if (can_skip_sstep(uprobe, regs))
>  		goto out;
>  
> -- 
> 1.8.1.2
>