When userland doesn't specify sigaction->sa_restorer, we try to put
the restorer code on the stack. But this breaks ia32 binaries with
non-executable stacks. We now put the restorer code on a gate page.
Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Arun Sharma <arun.sharma@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>