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Subject[tip:x86/urgent] x86, kvm: Remove incorrect redundant assembly constraint
Commit-ID:  cb7cb2864e758a1b040040bc55e404c677c911cb
Gitweb: http://git.kernel.org/tip/cb7cb2864e758a1b040040bc55e404c677c911cb
Author: H. Peter Anvin <hpa@linux.intel.com>
AuthorDate: Wed, 21 Nov 2012 14:41:21 -0800
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Mon, 26 Nov 2012 15:52:48 -0800

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>
---
arch/x86/kvm/emulate.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 39171cb..bba39bf 100644
--- 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) */

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