x86/speculation: Change FILL_RETURN_BUFFER to work with objtool

Change FILL_RETURN_BUFFER so that objtool groks it and can generate
correct ORC unwind information.

 - Since ORC is alternative invariant; that is, all alternatives
   should have the same ORC entries, the __FILL_RETURN_BUFFER body
   can not be part of an alternative.

   Therefore, move it out of the alternative and keep the alternative
   as a sort of jump_label around it.

 - Use the ANNOTATE_INTRA_FUNCTION_CALL annotation to white-list
   these 'funny' call instructions to nowhere.

 - Use UNWIND_HINT_EMPTY to 'fill' the speculation traps, otherwise
   objtool will consider them unreachable.

 - Move the RSP adjustment into the loop, such that the loop has a
   deterministic stack layout.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Alexandre Chartre <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

0 files changed, 0 insertions, 0 deletions