[05/18] x86: pvclock: create helper for pvclock data retrieval

Commit Message

Marcelo Tosatti Nov. 15, 2012, 12:08 a.m. UTC

Originally from Jeremy Fitzhardinge.

So code can be reused.

Signed-off-by: Marcelo Tosatti <[e-mail]>



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Comments

Glauber Costa Nov. 15, 2012, 12:27 p.m. UTC | #1

On 11/15/2012 04:08 AM, Marcelo Tosatti wrote:
> Originally from Jeremy Fitzhardinge.
> 
> So code can be reused.
> 
> Signed-off-by: Marcelo Tosatti <[e-mail]>
> 
I thought I had acked this one already?

But maybe I didn't...

Acked-by: Glauber Costa <[e-mail]>
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Patch

Index: vsyscall/arch/x86/kernel/pvclock.c
===================================================================
--- vsyscall.orig/arch/x86/kernel/pvclock.c
+++ vsyscall/arch/x86/kernel/pvclock.c
@@ -26,13 +26,6 @@  void pvclock_set_flags(u8 flags)
 	valid_flags = flags;
 }
 
-static u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
-{
-	u64 delta = native_read_tsc() - src->tsc_timestamp;
-	return pvclock_scale_delta(delta, src->tsc_to_system_mul,
-				   src->tsc_shift);
-}
-
 unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)
 {
 	u64 pv_tsc_khz = 1000000ULL << 32;
@@ -55,17 +48,12 @@  void pvclock_resume(void)
 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
 {
 	unsigned version;
-	cycle_t ret, offset;
+	cycle_t ret;
 	u64 last;
 	u8 flags;
 
 	do {
-		version = src->version;
-		rdtsc_barrier();
-		offset = pvclock_get_nsec_offset(src);
-		ret = src->system_time + offset;
-		flags = src->flags;
-		rdtsc_barrier();
+		version = __pvclock_read_cycles(src, &ret, &flags);
 	} while ((src->version & 1) || version != src->version);
 
 	if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&
Index: vsyscall/arch/x86/include/asm/pvclock.h
===================================================================
--- vsyscall.orig/arch/x86/include/asm/pvclock.h
+++ vsyscall/arch/x86/include/asm/pvclock.h
@@ -56,4 +56,32 @@  static inline u64 pvclock_scale_delta(u6
 	return product;
 }
 
+static __always_inline
+u64 pvclock_get_nsec_offset(const struct pvclock_vcpu_time_info *src)
+{
+	u64 delta = __native_read_tsc() - src->tsc_timestamp;
+	return pvclock_scale_delta(delta, src->tsc_to_system_mul,
+				   src->tsc_shift);
+}
+
+static __always_inline
+unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
+			       cycle_t *cycles, u8 *flags)
+{
+	unsigned version;
+	cycle_t ret, offset;
+	u8 ret_flags;
+
+	version = src->version;
+	rdtsc_barrier();
+	offset = pvclock_get_nsec_offset(src);
+	ret = src->system_time + offset;
+	ret_flags = src->flags;
+	rdtsc_barrier();
+
+	*cycles = ret;
+	*flags = ret_flags;
+	return version;
+}
+
 #endif /* _ASM_X86_PVCLOCK_H */