linux-kernel - [PATCH 1/2] uprobes: Use a helper instead of ptrace's single step enable

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Date:	Tue, 31 Jul 2012 13:52:27 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	oleg@...hat.com, ananth@...ibm.com, a.p.zijlstra@...llo.nl,
	mingo@...hat.com, srikar@...ux.vnet.ibm.com, roland@...k.frob.com,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH 1/2] uprobes: Use a helper instead of ptrace's single step enable

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

[0] http://lkml.kernel.org/20120730141638.GA5306@redhat.com

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 include/linux/uprobes.h |    4 ++++
 kernel/events/uprobes.c |   16 ++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index efe4b33..ea6603b 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -111,6 +111,10 @@ extern void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsig
 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 task_struct *child,
+		struct arch_uprobe *arch);
+extern void __weak arch_uprobe_disable_step(struct task_struct *child,
+		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 f935327..3a61f16 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1482,6 +1482,18 @@ static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
 	return uprobe;
 }
 
+void __weak arch_uprobe_enable_step(struct task_struct *child,
+		struct arch_uprobe *arch)
+{
+	user_enable_single_step(current);
+}
+
+void __weak arch_uprobe_disable_step(struct task_struct *child,
+		struct arch_uprobe *arch)
+{
+	user_disable_single_step(child);
+}
+
 /*
  * Run handler and ask thread to singlestep.
  * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
@@ -1528,7 +1540,7 @@ 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(current, &uprobe->arch);
 		return;
 	}
 
@@ -1569,7 +1581,7 @@ 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(current, &uprobe->arch);
 	xol_free_insn_slot(current);
 
 	spin_lock_irq(&current->sighand->siglock);
-- 
1.7.10.4

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