Add support for timeconting in userland.

This diff exposes parts of clock_gettime(2) and gettimeofday(2) to
userland via libc eliberating processes from the need for a context
switch everytime they want to count the passage of time.

If a timecounter clock can be exposed to userland than it needs to set
its tc_user member to a non-zero value. Tested with one or multiple
counters per architecture.

The timing data is shared through a pointer found in the new ELF
auxiliary vector AUX_openbsd_timekeep containing timehands information
that is frequently updated by the kernel.

Timing differences between the last kernel update and the current time
are adjusted in userland by the tc_get_timecount() function inside the
MD usertc.c file.

This permits a much more responsive environment, quite visible in
browsers, office programs and gaming (apparently one is are able to fly
in Minecraft now).

Tested by robert@, sthen@, naddy@, kmos@, phessler@, and many others!

OK from at least kettenis@, cheloha@, naddy@, sthen@

1 files changed, 2 insertions, 2 deletions

diff --git a/sys/arch/armv7/omap/gptimer.c b/sys/arch/armv7/omap/gptimer.c
index 7605845d5e2..97f9dc0ba0b 100644
--- a/sys/arch/armv7/omap/gptimer.c
+++ b/sys/arch/armv7/omap/gptimer.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: gptimer.c,v 1.7 2019/05/06 03:45:58 mlarkin Exp $ */
+/* $OpenBSD: gptimer.c,v 1.8 2020/07/06 13:33:07 pirofti Exp $ */
 /*
  * Copyright (c) 2007,2009 Dale Rahn <drahn@openbsd.org>
  *
@@ -117,7 +117,7 @@ int gptimer_irq = 0;
 u_int gptimer_get_timecount(struct timecounter *);
 
 static struct timecounter gptimer_timecounter = {
-	gptimer_get_timecount, NULL, 0x7fffffff, 0, "gptimer", 0, NULL
+	gptimer_get_timecount, NULL, 0x7fffffff, 0, "gptimer", 0, NULL, 0
 };
 
 volatile u_int32_t nexttickevent;