ftrace: Add return address pointer to ftrace_ret_stack

Storing this value will help prevent unwinders from getting out of sync
with the function graph tracer ret_stack.  Now instead of needing a
stateful iterator, they can compare the return address pointer to find
the right ret_stack entry.

Note that an array of 50 ftrace_ret_stack structs is allocated for every
task.  So when an arch implements this, it will add either 200 or 400
bytes of memory usage per task (depending on whether it's a 32-bit or
64-bit platform).

Signed-off-by: Josh Poimboeuf <[email protected]>
Acked-by: Steven Rostedt <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Byungchul Park <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Nilay Vaish <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/a95cfcc39e8f26b89a430c56926af0bb217bc0a1.1471607358.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <[email protected]>

0 files changed, 0 insertions, 0 deletions