kern: Add a mach host operation which returns elapsed time since bootup

Add host_get_uptime64() mach interface operation. It can be used to get
the time passed since the boot up.

* doc/mach.texi: Add the documentation for the operation
* include/mach/mach_host.defs: Add the interface
* include/mach/time_value.h: Extend the mappable time variable
* kern/mach_clock.c: Operation implementation
* kern/mach_clock.h: Add a new variable for storing uptime

Signed-off-by: Zhaoming Luo <zhmingluo@163.com>
Message-ID: <20241224015751.1282-1-zhmingluo@163.com>

5 files changed, 54 insertions, 0 deletions

diff --git a/doc/mach.texi b/doc/mach.texi
index f85288e0..f54ed655 100644
--- a/doc/mach.texi
+++ b/doc/mach.texi
@@ -5664,6 +5664,11 @@ Get the current time as seen by @var{host}.  On success, the time passed
 since the epoch is returned in @var{current_time}.
 @end deftypefun
 
+@deftypefun kern_return_t host_get_uptime64 (@w{host_t @var{host}}, @w{time_value64_t *@var{uptime}})
+Get the elapsed time since the boot up as seen by @var{host}.  On success, the time passed
+since the boot up is returned in @var{uptime}.
+@end deftypefun
+
 @deftypefun kern_return_t host_set_time64 (@w{host_priv_t @var{host_priv}}, @w{time_value64_t @var{new_time}})
 Set the time of @var{host_priv} to @var{new_time}.
 @end deftypefun
diff --git a/include/mach/mach_host.defs b/include/mach/mach_host.defs
index 8fd9d6b3..501ca0f6 100644
--- a/include/mach/mach_host.defs
+++ b/include/mach/mach_host.defs
@@ -386,3 +386,10 @@ routine	host_adjust_time64(
 routine	host_get_kernel_version(
 		host		: host_t;
 	out	kernel_version	: new_kernel_version_t);
+
+/*
+ *     Get the uptime on this host.
+ */
+routine	host_get_uptime64(
+		host		: host_t;
+	out	uptime		: time_value64_t);
diff --git a/include/mach/time_value.h b/include/mach/time_value.h
index e08707bc..7378c2cf 100644
--- a/include/mach/time_value.h
+++ b/include/mach/time_value.h
@@ -172,6 +172,8 @@ typedef struct mapped_time_value {
 	integer_t check_seconds;
 	struct time_value64 time_value;
 	int64_t check_seconds64;
+	struct time_value64 uptime_value;
+	int64_t check_upseconds64;
 } mapped_time_value_t;
 
 /* Macros for converting between struct timespec and time_value_t. */
diff --git a/kern/mach_clock.c b/kern/mach_clock.c
index 24609353..5501b7b8 100644
--- a/kern/mach_clock.c
+++ b/kern/mach_clock.c
@@ -69,6 +69,7 @@
 int		hz = HZ;		/* number of ticks per second */
 int		tick = (MICROSECONDS_IN_ONE_SECOND / HZ);	/* number of usec per tick */
 time_value64_t	time = { 0, 0 };	/* wallclock time (unadjusted) */
+time_value64_t	uptime = { 0, 0 };	/* time since bootup */
 unsigned long	elapsed_ticks = 0;	/* ticks elapsed since bootup */
 
 int		timedelta = 0;
@@ -109,6 +110,17 @@ MACRO_BEGIN								\
 	}								\
 MACRO_END
 
+#define update_mapped_uptime(uptime)					\
+MACRO_BEGIN								\
+	if (mtime != 0) {						\
+		mtime->check_upseconds64 = (uptime)->seconds;		\
+		__sync_synchronize();					\
+		mtime->uptime_value.nanoseconds = (uptime)->nanoseconds;\
+		__sync_synchronize();					\
+		mtime->uptime_value.seconds = (uptime)->seconds;	\
+	}								\
+MACRO_END
+
 #define read_mapped_time(time)						\
 MACRO_BEGIN								\
 	do {								\
@@ -119,6 +131,16 @@ MACRO_BEGIN								\
 	} while ((time)->seconds != mtime->check_seconds64);	\
 MACRO_END
 
+#define read_mapped_uptime(uptime)				    	\
+MACRO_BEGIN								\
+	do {								\
+		(uptime)->seconds = mtime->uptime_value.seconds;	\
+		__sync_synchronize();					\
+		(uptime)->nanoseconds = mtime->uptime_value.nanoseconds;\
+		__sync_synchronize();					\
+	} while ((uptime)->seconds != mtime->check_upseconds64);	\
+MACRO_END
+
 def_simple_lock_irq_data(static,	timer_lock)	/* lock for ... */
 timer_elt_data_t	timer_head;	/* ordered list of timeouts */
 					/* (doubles as end-of-list) */
@@ -230,6 +252,7 @@ void clock_interrupt(
 	     */
 	    if (timedelta == 0) {
 		time_value64_add_nanos(&time, usec * 1000);
+		time_value64_add_nanos(&uptime, usec * 1000);
 	    }
 	    else {
 		int	delta;
@@ -251,8 +274,10 @@ void clock_interrupt(
 		    timedelta -= tickdelta;
 		}
 		time_value64_add_nanos(&time, delta * 1000);
+		time_value64_add_nanos(&uptime, delta * 1000);
 	    }
 	    update_mapped_time(&time);
+	    update_mapped_uptime(&uptime);
 
 	    /*
 	     *	Schedule soft-interrupt for timeout if needed
@@ -571,6 +596,19 @@ host_adjust_time64(
 	return (KERN_SUCCESS);
 }
 
+/*
+ * Read the uptime (the elapsed time since boot up).
+ */
+kern_return_t
+host_get_uptime64(const host_t host, time_value64_t *uptime)
+{
+	if (host == HOST_NULL)
+		return (KERN_INVALID_HOST);
+
+	read_mapped_uptime(uptime);
+	return (KERN_SUCCESS);
+}
+
 void mapable_time_init(void)
 {
 	if (kmem_alloc_wired(kernel_map, (vm_offset_t *) &mtime, PAGE_SIZE)
@@ -578,6 +616,7 @@ void mapable_time_init(void)
 		panic("mapable_time_init");
 	memset((void *) mtime, 0, PAGE_SIZE);
 	update_mapped_time(&time);
+	update_mapped_uptime(&uptime);
 }
 
 int timeopen(dev_t dev, int flag, io_req_t ior)
diff --git a/kern/mach_clock.h b/kern/mach_clock.h
index 04ed4b99..d4f04f5e 100644
--- a/kern/mach_clock.h
+++ b/kern/mach_clock.h
@@ -41,6 +41,7 @@ extern int		hz;		/* number of ticks per second */
 extern int		tick;		/* number of usec per tick */
 
 extern time_value64_t	time; 		/* wallclock time (unadjusted) */
+extern time_value64_t	uptime;		/* time since bootup */
 
 typedef void timer_func_t(void *);