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uprobes: Introduce arch_uprobe_enable/disable_step() 

As Oleg pointed out in [0] uprobe should not use the ptrace interface
for enabling/disabling single stepping.

[0] 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.

We should also change handle_singlestep(), _disable_step(&uprobe->arch)
should be called before put_uprobe().

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>
This commit is contained in:
Sebastian Andrzej Siewior 2012-08-07 18:12:28 +02:00 committed by Oleg Nesterov
parent 499a4f3ec0
commit 9d77878226
2 changed files with 14 additions and 2 deletions
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2
include/linux/uprobes.h
View File

@ -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);

14
kernel/events/uprobes.c
View File

@ -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;
}
@ -1526,10 +1536,10 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
else
WARN_ON_ONCE(1);
arch_uprobe_disable_step(&uprobe->arch);
put_uprobe(uprobe);
utask->active_uprobe = NULL;
utask->state = UTASK_RUNNING;
user_disable_single_step(current);
xol_free_insn_slot(current);
spin_lock_irq(&current->sighand->siglock);