kprobes: kretprobe user entry-handler

Provide support to add an optional user defined callback to be run at
function entry of a kretprobe'd function.  Also modify the kprobe smoke
tests to include an entry-handler during the kretprobe sanity test.

Signed-off-by: Abhishek Sagar <sagar.abhishek@gmail.com>
Cc: Prasanna S Panchamukhi <prasanna@in.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Acked-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 6168c0a44172..4a6ce82ba039 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -152,8 +152,10 @@ static inline int arch_trampoline_kprobe(struct kprobe *p)
 struct kretprobe {
         struct kprobe kp;
         kretprobe_handler_t handler;
+        kretprobe_handler_t entry_handler;
         int maxactive;
         int nmissed;
+        size_t data_size;
         struct hlist_head free_instances;
         struct hlist_head used_instances;
 };
@@ -164,6 +166,7 @@ struct kretprobe_instance {
         struct kretprobe *rp;
         kprobe_opcode_t *ret_addr;
         struct task_struct *task;
+        char data[0];
 };
 
 struct kretprobe_blackpoint {