x86/paravirt: add sysret/sysexit pvops for returning to 32-bit compatibility userspace

In a 64-bit system, we need separate sysret/sysexit operations to
return to a 32-bit userspace.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citirx.com>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 3 deletions

diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c
index d4c0712a3e64..061d01df9ae6 100644
--- a/arch/x86/kernel/paravirt_patch_64.c
+++ b/arch/x86/kernel/paravirt_patch_64.c
@@ -14,8 +14,9 @@ DEF_NATIVE(pv_mmu_ops, flush_tlb_single, "invlpg (%rdi)");
 DEF_NATIVE(pv_cpu_ops, clts, "clts");
 DEF_NATIVE(pv_cpu_ops, wbinvd, "wbinvd");
 
-/* the three commands give us more control to how to return from a syscall */
-DEF_NATIVE(pv_cpu_ops, usergs_sysret, "swapgs; sysretq;");
+DEF_NATIVE(pv_cpu_ops, irq_enable_sysexit, "swapgs; sti; sysexit");
+DEF_NATIVE(pv_cpu_ops, usergs_sysret64, "swapgs; sysretq");
+DEF_NATIVE(pv_cpu_ops, usergs_sysret32, "swapgs; sysretl");
 DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs");
 
 unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
@@ -35,7 +36,9 @@ unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
                 PATCH_SITE(pv_irq_ops, irq_enable);
                 PATCH_SITE(pv_irq_ops, irq_disable);
                 PATCH_SITE(pv_cpu_ops, iret);
-                PATCH_SITE(pv_cpu_ops, usergs_sysret);
+                PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
+                PATCH_SITE(pv_cpu_ops, usergs_sysret32);
+                PATCH_SITE(pv_cpu_ops, usergs_sysret64);
                 PATCH_SITE(pv_cpu_ops, swapgs);
                 PATCH_SITE(pv_mmu_ops, read_cr2);
                 PATCH_SITE(pv_mmu_ops, read_cr3);