Re: [Xen-devel] [PATCH 1/2] x86_emulate: fix emulation of CMPXCHG

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Eugene Korenevsky <ekorenevsky@xxxxxxxxx> 04/28/15 11:54 PM >>>
>--- a/xen/arch/x86/x86_emulate/x86_emulate.c
>+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
>@@ -4343,7 +4343,8 @@ x86_emulate(
>/* Save real source value, then compare EAX against destination. */
>src.orig_val = src.val;
>src.val = _regs.eax;
>-        emulate_2op_SrcV("cmp", src, dst, _regs.eflags);
>+        /* EAX must be a minuend, dst must be a subtrahend. */
>+        emulate_2op_SrcV("cmp", dst, src, _regs.eflags);

Thanks, operands indeed need to be the other way around. The comment,
however, doesn't really look that helpful to me, and hence I intend to alter
it before committing (also getting it closer to what CMPS and SCAS have).

Should you submit further patches in the future, please also remember to
Cc relevant maintainers.

Jan


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