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/sparc64/dev/psycho.c b/sys/arch/sparc64/dev/psycho.c
index e24f804dff6..ce8d9a7bb9f 100644
--- a/sys/arch/sparc64/dev/psycho.c
+++ b/sys/arch/sparc64/dev/psycho.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: psycho.c,v 1.76 2019/06/25 22:30:56 dlg Exp $	*/
+/*	$OpenBSD: psycho.c,v 1.77 2020/07/06 13:33:08 pirofti Exp $	*/
 /*	$NetBSD: psycho.c,v 1.39 2001/10/07 20:30:41 eeh Exp $	*/
 
 /*
@@ -127,7 +127,7 @@ extern struct sparc_pci_chipset _sparc_pci_chipset;
 u_int stick_get_timecount(struct timecounter *);
 
 struct timecounter stick_timecounter = {
-	stick_get_timecount, NULL, ~0u, 0, "stick", 1000, NULL
+	stick_get_timecount, NULL, ~0u, 0, "stick", 1000, NULL, 0
 };
 
 /*