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KVM: Fix instruction size issue in pvclock scaling 

Commit de2d1a524e ("KVM: Fix register corruption in pvclock_scale_delta")
introduced a mul instruction that may have only a memory operand; the
assembler therefore cannot select the correct size:

   pvclock.s:229: Error: no instruction mnemonic suffix given and no register
operands; can't size instruction

In this example the assembler is:

         #APP
         mul -48(%rbp) ; shrd $32, %rdx, %rax
         #NO_APP

A simple solution is to use mulq.

Signed-off-by: Duncan Sands <baldrick@free.fr>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Duncan Sands 2011-08-30 10:58:22 +02:00 committed by Avi Kivity
parent b4ca46e4e8
commit 3b217116ed
1 changed files with 1 additions and 1 deletions
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2
arch/x86/include/asm/pvclock.h
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@ -44,7 +44,7 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
: "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
#elif defined(__x86_64__)
__asm__ (
"mul %[mul_frac] ; shrd $32, %[hi], %[lo]"
"mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
: [lo]"=a"(product),
[hi]"=d"(tmp)
: "0"(delta),