Merge pull request #63 from soby-mathew/sm/save_callee_saved_registers_in_cpu_context-1

Preserve x19-x29 across world switch for exception handling

diff --cc bl31/aarch64/bl31_entrypoint.S
Simple merge

diff --cc services/std_svc/psci/psci_entry.S
index 25adaa11e92a7cec6d118fe157b927987ca6874c,50f74a6c5a6dc380e3e515c14c1ce79dfa1a4aab..256c538dd4ee3f42593a284356459d04d0a36617
--- 1/services/std_svc/psci/psci_entry.S
--- 2/services/std_svc/psci/psci_entry.S
+++ b/services/std_svc/psci/psci_entry.S
@@@ -99,10 -101,9 +99,9 @@@ psci_aff_common_finish_entry
         * -IS-WBWA memory
         * --------------------------------------------
         */
 -      mov     x0, x19
 +      mrs     x0, mpidr_el1
        bl      platform_set_stack
  
-       zero_callee_saved_regs
        b       el3_exit
  _panic:
        b       _panic