From 952d1d7055c8cbf95b4ad2f90be5ed37db8a48ee Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Tue, 8 Jul 2008 15:07:01 -0700 Subject: [PATCH] xen64: add pvop for swapgs swapgs is a no-op under Xen, because the hypervisor makes sure the right version of %gs is current when switching between user and kernel modes. This means that the swapgs "implementation" can be inlined and used when the stack is unsafe (usermode). Unfortunately, it means that disabling patching will result in a non-booting kernel... Signed-off-by: Jeremy Fitzhardinge Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar --- arch/x86/xen/enlighten.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 9d94483b3b5..8b60982e457 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -1076,6 +1076,9 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = { .set_iopl_mask = xen_set_iopl_mask, .io_delay = xen_io_delay, + /* Xen takes care of %gs when switching to usermode for us */ + .swapgs = paravirt_nop, + .lazy_mode = { .enter = paravirt_enter_lazy_cpu, .leave = xen_leave_lazy, -- 2.41.0