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, 3 insertions, 3 deletions

diff --git a/lib/libc/crypt/bcrypt.c b/lib/libc/crypt/bcrypt.c
index 82de8fa33b7..ba45b104eda 100644
--- a/lib/libc/crypt/bcrypt.c
+++ b/lib/libc/crypt/bcrypt.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bcrypt.c,v 1.57 2016/08/26 08:25:02 guenther Exp $	*/
+/*	$OpenBSD: bcrypt.c,v 1.58 2020/07/06 13:33:05 pirofti Exp $	*/
 
 /*
  * Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
@@ -248,9 +248,9 @@ _bcrypt_autorounds(void)
 	char buf[_PASSWORD_LEN];
 	int duration;
 
-	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &before);
+	WRAP(clock_gettime)(CLOCK_THREAD_CPUTIME_ID, &before);
 	bcrypt_newhash("testpassword", r, buf, sizeof(buf));
-	clock_gettime(CLOCK_THREAD_CPUTIME_ID, &after);
+	WRAP(clock_gettime)(CLOCK_THREAD_CPUTIME_ID, &after);
 
 	duration = after.tv_sec - before.tv_sec;
 	duration *= 1000000;