[POC 2/5] task_struct : add additional member for sframe state

[Indu Bhagat <indu.bhagat@oracle.com>]

Add a new member to keep track of the SFrame sections for the current
task (program and its DSOs).

The definition of struct sframe_state is owned by the SFrame unwinder,
and added in a later commit.  Regarding the state management of the
task_struct.sframe_state:
  - Allocation and initialization is done at the task initialization
    time in the kernel.
  - Update: Not clear. We need to be able to track dlopen/dlclose, or
    additional shared libraries loaded via the dynamic linker at the
    task execution time.

Signed-off-by: Indu Bhagat <indu.bhagat@oracle.com>
---
 include/linux/sched.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index eed5d65b8d1f..fc0b0c720979 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -71,6 +71,7 @@ struct signal_struct;
 struct task_delay_info;
 struct task_group;
 struct user_event_mm;
+struct sframe_state;
 
 /*
  * Task state bitmask. NOTE! These bits are also
@@ -1534,6 +1535,10 @@ struct task_struct {
 	struct user_event_mm		*user_event_mm;
 #endif
 
+#ifdef CONFIG_USER_UNWINDER_SFRAME
+	struct sframe_state		*sframe_state;
+#endif
+
 	/*
 	 * New fields for task_struct should be added above here, so that
 	 * they are included in the randomized portion of task_struct.
-- 
2.39.2