core: arm64.S: spectre workaround
core: arm64.S: spectre workaround

If build with CFG_CORE_WORKAROUND_SPECTRE_BP_SEC=y invalidate branch
predictor on all secure world exceptions originating in secure EL0
(secure user space).

Fixes CVE-2017-5715

Reviewed-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>
Tested-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org> (HiKey960)
Signed-off-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os