Commit 9d778782 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Oleg Nesterov
Browse files

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: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent 499a4f3e

include/linux/uprobes.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

kernel/events/uprobes.c

+12 −2
Original line number Diff line number Diff line
@@ -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);

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