x86: fix asm() constraint for GS selector update

Exception fixup code may alter the operand, which ought to be reflected
in the constraint.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Julien Grall <julien.grall@linaro.org>

diff --git a/xen/arch/x86/x86_64/mm.c b/xen/arch/x86/x86_64/mm.c
index 11746730b4ac41540ad18af93ee522bb3689dc19..34cd8457cfb49f89f756bd7843f917c89bdf5479 100644 (file)
--- a/xen/arch/x86/x86_64/mm.c
+++ b/xen/arch/x86/x86_64/mm.c
@@ -1062,7 +1062,7 @@ long do_set_segment_base(unsigned int which, unsigned long base)
             "     jmp  1b             \n"
             ".previous                \n"
             _ASM_EXTABLE(1b, 2b)
-            : : "r" (base&0xffff) );
+            : "+r" (base) );
         break;
 
     default: