[RFC PATCH v5 8/9] Link frame_info to thread_info

[Philipp Rudo <prudo at linux dot vnet dot ibm dot com>]

Linux kernel stacks on S390 are spread over several memory locations.
These locations differ for every kernel task/thread.  Thus we need to know
to which task/thread a frame belongs to check whether a stack pointer is
valid and when to stop unwinding.  To do so add a pointer to the
corresponding thread_info to frame_info.

This connection already exists implicitly, via inferior_ptid, due to the
fact that switch_to_thread reinitializes the frame cache.

gdb/ChangeLog:

	* frame.h (frame_get_thread): New extern declaration.
	* frame.c (frame_info) <thread>: New field.
	(frame_get_thread): New function.
	(create_sentinel_frame, create_new_frame, get_prev_frame_raw): Set
	new field.
---
 gdb/frame.c | 12 ++++++++++++
 gdb/frame.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/gdb/frame.c b/gdb/frame.c
index 0b04a4ebac..fe81c37755 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -101,6 +101,9 @@ struct frame_info
   /* The frame's address space.  */
   const address_space *aspace;
 
+  /* The thread this frame belongs to.  */
+  struct thread_info *thread;
+
   /* The frame's low-level unwinder and corresponding cache.  The
      low-level unwinder is responsible for unwinding register values
      for the previous frame.  The low-level unwind methods are
@@ -157,6 +160,12 @@ struct frame_info
   const char *stop_string;
 };
 
+struct thread_info *
+frame_get_thread (struct frame_info *frame)
+{
+  return frame->thread;
+}
+
 /* A frame stash used to speed up frame lookups.  Create a hash table
    to stash frames previously accessed from the frame cache for
    quicker subsequent retrieval.  The hash table is emptied whenever
@@ -1520,6 +1529,7 @@ create_sentinel_frame (struct program_space *pspace, struct regcache *regcache)
   frame->level = -1;
   frame->pspace = pspace;
   frame->aspace = regcache->aspace ();
+  frame->thread = inferior_thread ();
   /* Explicitly initialize the sentinel frame's cache.  Provide it
      with the underlying regcache.  In the future additional
      information, such as the frame's thread will be added.  */
@@ -1744,6 +1754,7 @@ create_new_frame (CORE_ADDR addr, CORE_ADDR pc)
   /* We currently assume that frame chain's can't cross spaces.  */
   fi->pspace = fi->next->pspace;
   fi->aspace = fi->next->aspace;
+  fi->thread = fi->next->thread;
 
   /* Select/initialize both the unwind function and the frame's type
      based on the PC.  */
@@ -2155,6 +2166,7 @@ get_prev_frame_raw (struct frame_info *this_frame)
      spaces.  */
   prev_frame->pspace = this_frame->pspace;
   prev_frame->aspace = this_frame->aspace;
+  prev_frame->thread = this_frame->thread;
 
   /* Don't yet compute ->unwind (and hence ->type).  It is computed
      on-demand in get_frame_type, frame_register_unwind, and
diff --git a/gdb/frame.h b/gdb/frame.h
index d5800b78c2..e908cc5172 100644
--- a/gdb/frame.h
+++ b/gdb/frame.h
@@ -103,6 +103,8 @@ enum frame_id_stack_status
 
 struct frame_info;
 
+extern struct thread_info *frame_get_thread (struct frame_info *frame);
+
 /* The frame object's ID.  This provides a per-frame unique identifier
    that can be used to relocate a `struct frame_info' after a target
    resume or a frame cache destruct.  It of course assumes that the
-- 
2.13.5