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Commit de2d1a52 authored by Zachary Amsden's avatar Zachary Amsden Committed by Avi Kivity
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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: default avatarZachary Amsden <zamsden@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent a0a8eaba

arch/x86/include/asm/pvclock.h

+7 −2
Original line number Diff line number Diff line
@@ -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