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, 1 insertions, 1 deletions

diff --git a/sys/dev/pv/hyperv.c b/sys/dev/pv/hyperv.c
index b32facdacb1..b9ee2feec4c 100644
--- a/sys/dev/pv/hyperv.c
+++ b/sys/dev/pv/hyperv.c
@@ -141,7 +141,7 @@ struct {
 };
 
 struct timecounter hv_timecounter = {
-	hv_gettime, 0, 0xffffffff, 10000000, "hyperv", 9001
+	hv_gettime, 0, 0xffffffff, 10000000, "hyperv", 9001, NULL, 0
 };
 
 struct cfdriver hyperv_cd = {