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KVM: Fix register corruption in pvclock_scale_delta 

The 128-bit multiply in pvclock.h was missing an output constraint for
EDX which caused a register corruption to appear.  Thanks to Ulrich for
diagnosing the EDX corruption and Avi for providing this fix.

Signed-off-by: Zachary Amsden <zamsden@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Zachary Amsden 2011-06-15 20:50:04 -07:00 committed by Avi Kivity
parent a0a8eaba16
commit de2d1a524e
1 changed files with 7 additions and 2 deletions
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9
arch/x86/include/asm/pvclock.h
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@ -22,6 +22,8 @@ static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
u64 product;
#ifdef __i386__
u32 tmp1, tmp2;
#else
ulong tmp;
#endif
if (shift < 0)
@ -42,8 +44,11 @@ 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 %%rdx ; shrd $32,%%rdx,%%rax"
: "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );
"mul %[mul_frac] ; shrd $32, %[hi], %[lo]"
: [lo]"=a"(product),
[hi]"=d"(tmp)
: "0"(delta),
[mul_frac]"rm"((u64)mul_frac));
#else
#error implement me!
#endif