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

[Srikar Dronamraju <srikar@linux.vnet.ibm.com>]

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

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@us.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.