x86, kvm: Remove incorrect redundant assembly constraint

In __emulate_1op_rax_rdx, we use "+a" and "+d" which are input/output
constraints, and *then* use "a" and "d" as input constraints.  This is
incorrect, but happens to work on some versions of gcc.

However, it breaks gcc with -O0 and icc, and may break on future
versions of gcc.

Reported-and-tested-by: Melanie Blower <melanie.blower@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/r/B3584E72CFEBED439A3ECA9BCE67A4EF1B17AF90@FMSMSX107.amr.corp.intel.com
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 39171cb..bba39bf 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -426,8 +426,7 @@ static void invalidate_registers(struct x86_emulate_ctxt *ctxt)
                        _ASM_EXTABLE(1b, 3b)                            \
                        : "=m" ((ctxt)->eflags), "=&r" (_tmp),          \
                          "+a" (*rax), "+d" (*rdx), "+qm"(_ex)          \
-                       : "i" (EFLAGS_MASK), "m" ((ctxt)->src.val),     \
-                         "a" (*rax), "d" (*rdx));                      \
+                       : "i" (EFLAGS_MASK), "m" ((ctxt)->src.val));    \
        } while (0)
 
 /* instruction has only one source operand, destination is implicit (e.g. mul, div, imul, idiv) */