[PATCH v4 3.0-rc2-tip 11/22] 11: uprobes: get the breakpoint address.

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

On a breakpoint hit, 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 4590e9a..838fbaa 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -161,6 +161,7 @@ struct vm_area_struct;
 extern int mmap_uprobe(struct vm_area_struct *vma);
 extern void dup_mmap_uprobe(struct mm_struct *old_mm, struct mm_struct *mm);
 extern void free_uprobes_xol_area(struct mm_struct *mm);
+extern unsigned long __weak get_uprobe_bkpt_addr(struct pt_regs *regs);
 #else /* CONFIG_UPROBES is not defined */
 static inline int register_uprobe(struct inode *inode, loff_t offset,
 				struct uprobe_consumer *consumer)
@@ -181,5 +182,9 @@ static inline int mmap_uprobe(struct vm_area_struct *vma)
 }
 static inline void free_uprobe_utask(struct task_struct *tsk) {}
 static inline void free_uprobes_xol_area(struct mm_struct *mm) {}
+static inline unsigned long get_uprobe_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 d19c3b0..fa9e9ba 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -1263,6 +1263,17 @@ static void xol_free_insn_slot(struct task_struct *tsk)
 						__func__, slot_addr);
 }
 
+/**
+ * get_uprobe_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 __weak get_uprobe_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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