linux-kernel - [RFC] [PATCH 2.6.37-rc5-tip 12/20] 12: uprobes: get the breakpoint address.

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Message-Id: <20101216095936.23751.62727.sendpatchset@localhost6.localdomain6>
Date:	Thu, 16 Dec 2010 15:29:36 +0530
From:	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...e.hu>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>,
	Christoph Hellwig <hch@...radead.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Oleg Nesterov <oleg@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux-mm <linux-mm@...r.kernel.org>,
	Jim Keniston <jkenisto@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	SystemTap <systemtap@...rces.redhat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: [RFC] [PATCH 2.6.37-rc5-tip 12/20] 12: uprobes: get the breakpoint address.


On a breakpoint hit, perform a architecture specific calculation to
return the address where the breakpoint was hit.

Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@...ibm.com>
---
 include/linux/uprobes.h |    5 +++++
 kernel/uprobes.c        |   11 +++++++++++
 2 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index a631c42..ee12b2e 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -154,6 +154,7 @@ extern void uprobe_free_utask(struct task_struct *tsk);
 
 struct vm_area_struct;
 extern void uprobe_mmap(struct vm_area_struct *vma);
+extern unsigned long uprobes_get_bkpt_addr(struct pt_regs *regs);
 extern void uprobe_dup_mmap(struct mm_struct *old_mm, struct mm_struct *mm);
 extern void uprobes_free_xol_area(struct mm_struct *mm);
 #else /* CONFIG_UPROBES is not defined */
@@ -173,5 +174,9 @@ static inline void uprobe_dup_mmap(struct mm_struct *old_mm,
 static inline void uprobe_free_utask(struct task_struct *tsk) {}
 static inline void uprobe_mmap(struct vm_area_struct *vma) { }
 static inline void uprobes_free_xol_area(struct mm_struct *mm) {}
+static inline unsigned long uprobes_get_bkpt_addr(struct pt_regs *regs)
+{
+	return 0;
+}
 #endif /* CONFIG_UPROBES */
 #endif	/* _LINUX_UPROBES_H */
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
index 09e36f6..f486c4f 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -976,6 +976,17 @@ static void xol_free_insn_slot(struct task_struct *tsk, unsigned long slot_addr)
 						__func__, slot_addr);
 }
 
+/**
+ * uprobes_get_bkpt_addr - compute address of bkpt given post-bkpt regs
+ * @regs: Reflects the saved state of the task after it has hit a breakpoint
+ * instruction.
+ * Return the address of the breakpoint instruction.
+ */
+unsigned long uprobes_get_bkpt_addr(struct pt_regs *regs)
+{
+	return instruction_pointer(regs) - UPROBES_BKPT_INSN_SIZE;
+}
+
 /*
  * Called with no locks held.
  * Called in context of a exiting or a exec-ing thread.
--
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