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SubjectRe: [PATCH 1/7] uprobes: Introduce arch_uprobe_enable/disable_step()
* Oleg Nesterov <oleg@redhat.com> [2012-09-03 17:25:59]:

> From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>
> As Oleg pointed out in [0] uprobe should not use the ptrace interface
> for enabling/disabling single stepping.
>
> [0] http://lkml.kernel.org/20120730141638.GA5306@redhat.com

I think the link should be
http://lkml.kernel.org/r/20120730141638.GA5306@redhat.com


>
> Add the new "__weak arch" helpers which simply call user_*_single_step()
> as a preparation. This is only needed to not break the powerpc port, we
> will fold this logic into arch_uprobe_pre/post_xol() hooks later.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

> ---
> include/linux/uprobes.h | 2 ++
> kernel/events/uprobes.c | 14 ++++++++++++--
> 2 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
> index 6d4fe79..e6f0331 100644
> --- a/include/linux/uprobes.h
> +++ b/include/linux/uprobes.h
> @@ -112,6 +112,8 @@ extern void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm);
> extern void uprobe_free_utask(struct task_struct *t);
> extern void uprobe_copy_process(struct task_struct *t);
> extern unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs);
> +extern void __weak arch_uprobe_enable_step(struct arch_uprobe *arch);
> +extern void __weak arch_uprobe_disable_step(struct arch_uprobe *arch);
> extern int uprobe_post_sstep_notifier(struct pt_regs *regs);
> extern int uprobe_pre_sstep_notifier(struct pt_regs *regs);
> extern void uprobe_notify_resume(struct pt_regs *regs);
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 82a1043..125d1b7 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1444,6 +1444,16 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
> return uprobe;
> }
>
> +void __weak arch_uprobe_enable_step(struct arch_uprobe *arch)
> +{
> + user_enable_single_step(current);
> +}
> +
> +void __weak arch_uprobe_disable_step(struct arch_uprobe *arch)
> +{
> + user_disable_single_step(current);
> +}
> +
> /*
> * Run handler and ask thread to singlestep.
> * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
> @@ -1490,7 +1500,7 @@ static void handle_swbp(struct pt_regs *regs)
>
> utask->state = UTASK_SSTEP;
> if (!pre_ssout(uprobe, regs, bp_vaddr)) {
> - user_enable_single_step(current);
> + arch_uprobe_enable_step(&uprobe->arch);
> return;
> }
>
> @@ -1529,7 +1539,7 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
> put_uprobe(uprobe);
> utask->active_uprobe = NULL;
> utask->state = UTASK_RUNNING;
> - user_disable_single_step(current);
> + arch_uprobe_disable_step(&uprobe->arch);
> xol_free_insn_slot(current);
>
> spin_lock_irq(&current->sighand->siglock);
> --
> 1.5.5.1
>



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