This is a note to let you know that I've just added the patch titled
x86: pvclock: Move scale_delta into common header
to the 2.6.32-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.32.git;a=summary
The filename of the patch is:
0001-x86-pvclock-Move-scale_delta-into-common-header.patch
and it can be found in the queue-2.6.32 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.32 longterm
tree,
please let <[email protected]> know about it.
>From [email protected] Thu May 5 16:06:35 2011
From: Marcelo Tosatti <[email protected]>
Date: Wed, 04 May 2011 09:31:27 -0300
Subject: x86: pvclock: Move scale_delta into common header
To: [email protected]
Cc: "Serge E. Hallyn" <[email protected]>, Zachary Amsden
<[email protected]>, Marcelo Tosatti <[email protected]>, [email protected],
[email protected]
Message-ID: <[email protected]>
From: Zachary Amsden <[email protected]>
(cherry-picked from commit 347bb4448c2155eb2310923ccaa4be5677649003)
The scale_delta function for shift / multiply with 31-bit
precision moves to a common header so it can be used by both
kernel and kvm module.
Signed-off-by: Zachary Amsden <[email protected]>
Signed-off-by: Marcelo Tosatti <[email protected]>
BugLink: http://bugs.launchpad.net/bugs/714335
Signed-off-by: Serge E. Hallyn <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
arch/x86/include/asm/pvclock.h | 38 ++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/pvclock.c | 3 ++-
2 files changed, 40 insertions(+), 1 deletion(-)
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -12,4 +12,42 @@ void pvclock_read_wallclock(struct pvclo
struct timespec *ts);
void pvclock_resume(void);
+/*
+ * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
+ * yielding a 64-bit result.
+ */
+static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
+{
+ u64 product;
+#ifdef __i386__
+ u32 tmp1, tmp2;
+#endif
+
+ if (shift < 0)
+ delta >>= -shift;
+ else
+ delta <<= shift;
+
+#ifdef __i386__
+ __asm__ (
+ "mul %5 ; "
+ "mov %4,%%eax ; "
+ "mov %%edx,%4 ; "
+ "mul %5 ; "
+ "xor %5,%5 ; "
+ "add %4,%%eax ; "
+ "adc %5,%%edx ; "
+ : "=A" (product), "=r" (tmp1), "=r" (tmp2)
+ : "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) );
+#else
+#error implement me!
+#endif
+
+ return product;
+}
+
#endif /* _ASM_X86_PVCLOCK_H */
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -74,7 +74,8 @@ static inline u64 scale_delta(u64 delta,
static u64 pvclock_get_nsec_offset(struct pvclock_shadow_time *shadow)
{
u64 delta = native_read_tsc() - shadow->tsc_timestamp;
- return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);
+ return pvclock_scale_delta(delta, shadow->tsc_to_nsec_mul,
+ shadow->tsc_shift);
}
/*
Patches currently in longterm-queue-2.6.32 which might be from
[email protected] are
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/0003-KVM-x86-Fix-kvmclock-bug.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/0001-x86-pvclock-Move-scale_delta-into-common-header.patch
/home/gregkh/linux/longterm/longterm-queue-2.6.32/queue-2.6.32/kvm-x86-fix-a-possible-backwards-warp-of-kvmclock.patch
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