X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/935ed37a5c468c8a1c07408573c08b8b7ef80e8b..593a1d5fd87cdf5b46dd5fcb84467b432cea0f91:/osfmk/i386/rtclock.h

diff --git a/osfmk/i386/rtclock.h b/osfmk/i386/rtclock.h
index 904b38786..e3ea716d4 100644
--- a/osfmk/i386/rtclock.h
+++ b/osfmk/i386/rtclock.h
@@ -40,8 +40,90 @@
 #ifndef _I386_RTCLOCK_H_
 #define _I386_RTCLOCK_H_
 
+#ifndef ASSEMBLER
+typedef struct rtc_nanotime {
+	uint64_t	tsc_base;		/* timestamp */
+	uint64_t	ns_base;		/* nanoseconds */
+	uint32_t	scale;			/* tsc -> nanosec multiplier */
+	uint32_t	shift;			/* tsc -> nanosec shift/div */
+						/* shift is overloaded with
+						 * lower 32bits of tsc_freq
+						 * on slower machines (SLOW_TSC_THRESHOLD) */
+	uint32_t	generation;		/* 0 == being updated */
+	uint32_t	spare1;
+} rtc_nanotime_t;
+
 #include <kern/etimer.h>
 
 struct cpu_data;
 
+extern void	_rtc_nanotime_store(
+			uint64_t	tsc,
+			uint64_t	nsec,
+			uint32_t	scale,
+			uint32_t	shift,
+			rtc_nanotime_t	*dst);
+
+extern uint64_t	_rtc_nanotime_read(
+			rtc_nanotime_t	*rntp,
+			int		slow);
+
+extern rtc_nanotime_t	rtc_nanotime_info;
+#endif
+
+#define	SLOW_TSC_THRESHOLD	1000067800	/* TSC is too slow for regular nanotime() algorithm */
+
+#if defined(__i386__)
+/*
+ * Assembly snippet included in exception handlers and rtc_nanotime_read()
+ * %edi points to nanotime info struct
+ * %edx:%eax returns nanotime
+ */
+#define RTC_NANOTIME_READ_FAST()					  \
+0:	movl	RNT_GENERATION(%edi),%esi	/* being updated? */	; \
+	testl	%esi,%esi						; \
+	jz	0b				/* wait until done */	; \
+	rdtsc								; \
+	lfence								; \
+	subl	RNT_TSC_BASE(%edi),%eax					; \
+	sbbl	RNT_TSC_BASE+4(%edi),%edx	/* tsc - tsc_base */	; \
+	movl	RNT_SCALE(%edi),%ecx		/* * scale factor */	; \
+	movl	%edx,%ebx						; \
+	mull	%ecx							; \
+	movl	%ebx,%eax						; \
+	movl	%edx,%ebx						; \
+	mull	%ecx							; \
+	addl	%ebx,%eax						; \
+	adcl	$0,%edx							; \
+	addl	RNT_NS_BASE(%edi),%eax		/* + ns_base */		; \
+	adcl	RNT_NS_BASE+4(%edi),%edx				; \
+	cmpl	RNT_GENERATION(%edi),%esi	/* check for update */	; \
+	jne	0b				/* do it all again */
+
+#elif defined(__x86_64__)
+
+/*
+ * Assembly snippet included in exception handlers and rtc_nanotime_read()
+ * %rdi points to nanotime info struct.
+ * %rax returns nanotime
+ */
+#define RTC_NANOTIME_READ_FAST()					  \
+0:	movl	RNT_GENERATION(%rdi),%esi				; \
+	test	%esi,%esi			/* info updating? */	; \
+	jz	0b				/* - wait if so */	; \
+	rdtsc								; \
+	lfence								; \
+	shlq	$32,%rdx						; \
+	orq	%rdx,%rax			/* %rax := tsc */	; \
+	subq	RNT_TSC_BASE(%rdi),%rax		/* tsc - tsc_base */	; \
+	xorq	%rcx,%rcx						; \
+	movl	RNT_SCALE(%rdi),%ecx					; \
+	mulq	%rcx				/* delta * scale */	; \
+	shrdq	$32,%rdx,%rax			/* %rdx:%rax >>= 32 */	; \
+	addq	RNT_NS_BASE(%rdi),%rax		/* add ns_base */	; \
+	cmpl	RNT_GENERATION(%rdi),%esi	/* repeat if changed */ ; \
+	jne	0b
+
+#endif
+
 #endif /* _I386_RTCLOCK_H_ */