amd64: less code and data in the upper half

Call jumpToKernel() in sysret()/iret() so that there is less
code and data in the upper half, and, especially, current
goroutine's stack and user regs will not be accessed from the
upper half (also with the help from previous patches which make
less code in userCR3 context).

jumpToUser() will not be needed, because current goroutine's stack
and return value in the stack is lower half address.

It is prepared for KPTI for gvisor.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@antfin.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>

0 files changed, 0 insertions, 0 deletions