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Add new KERN_CPUSTATS sysctl(2) so we can identify offline CPUs.

Because of hw.smt we need a way to determine whether a given CPU is "online"
or "offline" from userspace.  KERN_CPTIME2 is an array, and so cannot be
cleanly extended for this purpose, so add a new sysctl(2) KERN_CPUSTATS
with an extensible struct.  At the moment it's just KERN_CPTIME2 with a
flags member, but it can grow as needed.

KERN_CPUSTATS appears to have been defined by BSDi long ago, but there are
few (if any) packages in the wild still using the symbol so breakage in ports
should be near zero.  No other system inherited the symbol from BSDi, either.

Then, use the new sysctl(2) in systat(1) and top(1):

  - systat(1) draws placeholder marks ('-') instead of percentages for
    offline CPUs in the cpu view.

  - systat(1) omits offline CPU ticks when drawing the "big bar" in
    the vmstat view.  The upshot is that the bar isn't half idle when
    half your logical CPUs are disabled.

  - top(1) does not draw lines for offline CPUs; if CPUs toggle on or
    offline in interactive mode we redraw the display to expand/reduce
    space for the new/missing CPUs.  This is consistent with what some
    top(1) implementations do on Linux.

  - top(1) omits offline CPUs from the totals when CPU totals are
    combined into a single line (the '-1' flag).

Originally prompted by deraadt@.  Discussed endlessly with deraadt@,
ketennis@, and sthen@.  Tested by jmc@ and jca@.  Earlier versions also
discussed with jca@.  Earlier versions tested by jmc@, tb@, and many
others.

docs ok jmc@, kernel bits ok ketennis@, everything ok sthen@,
"Is your stuff in yet?" deraadt@

/*	$OpenBSD: cpu.c,v 1.9 2018/11/17 23:10:08 cheloha Exp $	*/

/*
 * Copyright (c) 2013 Reyk Floeter <reyk@openbsd.org>
 * Copyright (c) 2001, 2007 Can Erkin Acar <canacar@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* CPU percentages() function from usr.bin/top/util.c:
 *
 *  Top users/processes display for Unix
 *  Version 3
 *
 * Copyright (c) 1984, 1989, William LeFebvre, Rice University
 * Copyright (c) 1989, 1990, 1992, William LeFebvre, Northwestern University
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR OR HIS EMPLOYER BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/signal.h>
#include <sys/sched.h>
#include <sys/sysctl.h>

#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include "systat.h"

void		 print_cpu(void);
int		 read_cpu(void);
int		 select_cpu(void);
static void	 cpu_info(void);
static void	 print_fld_percentage(field_def *, double);
static int	 percentages(int, int64_t *, int64_t *, int64_t *, int64_t *);

field_def fields_cpu[] = {
	{ "CPU", 4, 8, 1, FLD_ALIGN_LEFT, -1, 0, 0, 0 },
	{ "User", 10, 20, 1, FLD_ALIGN_RIGHT, -1, 0, 0, 0 },
	{ "Nice", 10, 20, 1, FLD_ALIGN_RIGHT, -1, 0, 0, 0 },
	{ "System", 10, 20, 1, FLD_ALIGN_RIGHT, -1, 0, 0, 0 },
	{ "Spin", 10, 20, 1, FLD_ALIGN_RIGHT, -1, 0, 0, 0 },
	{ "Interrupt", 10, 20, 1, FLD_ALIGN_RIGHT, -1, 0, 0, 0 },
	{ "Idle", 10, 20, 1, FLD_ALIGN_RIGHT, -1, 0, 0, 0 },
};

#define FLD_CPU_CPU	FIELD_ADDR(fields_cpu, 0)
#define FLD_CPU_USR	FIELD_ADDR(fields_cpu, 1)
#define FLD_CPU_NIC	FIELD_ADDR(fields_cpu, 2)
#define FLD_CPU_SYS	FIELD_ADDR(fields_cpu, 3)
#define FLD_CPU_SPIN	FIELD_ADDR(fields_cpu, 4)
#define FLD_CPU_INT	FIELD_ADDR(fields_cpu, 5)
#define FLD_CPU_IDLE	FIELD_ADDR(fields_cpu, 6)

/* Define views */
field_def *view_cpu_0[] = {
	FLD_CPU_CPU, FLD_CPU_USR, FLD_CPU_NIC, FLD_CPU_SYS, FLD_CPU_SPIN,
	FLD_CPU_INT, FLD_CPU_IDLE, NULL
};

/* Define view managers */
struct view_manager cpu_mgr = {
	"cpu", select_cpu, read_cpu, NULL, print_header,
	print_cpu, keyboard_callback, NULL, NULL
};

field_view views_cpu[] = {
	{ view_cpu_0, "cpu", 'C', &cpu_mgr },
	{ NULL, NULL, 0, NULL }
};

int	  cpu_count;
int64_t	 *cpu_states;
struct cpustats *cpu_diff, *cpu_old, *cpu_tm;

/*
 * percentages(cnt, out, new, old, diffs) - calculate percentage change
 * between array "old" and "new", putting the percentages in "out".
 * "cnt" is size of each array and "diffs" is used for scratch space.
 * The array "old" is updated on each call.
 * The routine assumes modulo arithmetic.  This function is especially
 * useful on BSD machines for calculating cpu state percentages.
 */
static int
percentages(int cnt, int64_t *out, int64_t *new, int64_t *old, int64_t *diffs)
{
	int64_t change, total_change, *dp, half_total;
	int i;

	/* initialization */
	total_change = 0;
	dp = diffs;

	/* calculate changes for each state and the overall change */
	for (i = 0; i < cnt; i++) {
		if ((change = *new - *old) < 0) {
			/* this only happens when the counter wraps */
			change = INT64_MAX - *old + *new;
		}
		total_change += (*dp++ = change);
		*old++ = *new++;
	}

	/* avoid divide by zero potential */
	if (total_change == 0)
		total_change = 1;

	/* calculate percentages based on overall change, rounding up */
	half_total = total_change / 2l;
	for (i = 0; i < cnt; i++)
		*out++ = ((*diffs++ * 1000 + half_total) / total_change);

	/* return the total in case the caller wants to use it */
	return (total_change);
}

static void
cpu_info(void)
{
	int	 cpustats_mib[] = { CTL_KERN, KERN_CPUSTATS, 0 }, i;
	int64_t *tmpstate;
	size_t	 size;

	size = sizeof(*cpu_tm);
	for (i = 0; i < cpu_count; i++) {
		cpustats_mib[2] = i;
		tmpstate = cpu_states + (CPUSTATES * i);
		if (sysctl(cpustats_mib, 3, &cpu_tm[i], &size, NULL, 0) < 0)
			error("sysctl KERN_CPUSTATS");
		percentages(CPUSTATES, tmpstate, cpu_tm[i].cs_time,
		    cpu_old[i].cs_time, cpu_diff[i].cs_time);
	}
}

static void
print_fld_percentage(field_def *fld, double val)
{
	if (fld == NULL)
		return;

	tb_start();
	tbprintf(val >= 1000 ? "%4.0f%%" : "%4.1f%%", val / 10.);
	print_fld_tb(fld);
	tb_end();
}

int
select_cpu(void)
{
	return (0);
}

int
read_cpu(void)
{
	cpu_info();
	num_disp = cpu_count;
	return (0);
}

int
initcpu(void)
{
	field_view	*v;
	size_t		 size = sizeof(cpu_count);
	int		 mib[2], i;

	mib[0] = CTL_HW;
	mib[1] = HW_NCPU;
	if (sysctl(mib, 2, &cpu_count, &size, NULL, 0) == -1)
		return (-1);
	if ((cpu_states = calloc(cpu_count,
	    CPUSTATES * sizeof(int64_t))) == NULL)
		return (-1);
	if ((cpu_tm = calloc(cpu_count, sizeof(*cpu_tm))) == NULL ||
	    (cpu_old = calloc(cpu_count, sizeof(*cpu_old))) == NULL ||
	    (cpu_diff = calloc(cpu_count, sizeof(*cpu_diff))) == NULL)
		return (-1);

	for (v = views_cpu; v->name != NULL; v++)
		add_view(v);

	read_cpu();

	return(1);
}

#define ADD_EMPTY_LINE \
	do {								\
		if (cur >= dispstart && cur < end) 			\
			end_line();					\
		if (++cur >= end)					\
			return;						\
	} while (0)

#define ADD_LINE_CPU(v, _cs) do {					\
	if (cur >= dispstart && cur < end) { 				\
		print_fld_size(FLD_CPU_CPU, (v));			\
		if (cpu_tm[v].cs_flags & CPUSTATS_ONLINE) {		\
			print_fld_percentage(FLD_CPU_USR, _cs[CP_USER]);\
			print_fld_percentage(FLD_CPU_NIC, _cs[CP_NICE]);\
			print_fld_percentage(FLD_CPU_SYS, _cs[CP_SYS]);	\
			print_fld_percentage(FLD_CPU_SPIN, _cs[CP_SPIN]);\
			print_fld_percentage(FLD_CPU_INT, _cs[CP_INTR]);\
			print_fld_percentage(FLD_CPU_IDLE, _cs[CP_IDLE]);\
		} else {						\
			print_fld_str(FLD_CPU_USR, "-");		\
			print_fld_str(FLD_CPU_NIC, "-");		\
			print_fld_str(FLD_CPU_SYS, "-");		\
			print_fld_str(FLD_CPU_SPIN, "-");		\
			print_fld_str(FLD_CPU_INT, "-");		\
			print_fld_str(FLD_CPU_IDLE, "-");		\
		}							\
		end_line();						\
	}								\
	if (++cur >= end)						\
		return;							\
} while (0)

void
print_cpu(void)
{
	int		cur = 0, c, i;
	int		end = dispstart + maxprint;
	int64_t		*states;
	double		value[CPUSTATES];

	if (end > num_disp)
		end = num_disp;

	for (c = 0; c < cpu_count; c++) {
		states = cpu_states + (CPUSTATES * c);

		for (i = 0; i < CPUSTATES; i++)
			value[i] = *states++;

		ADD_LINE_CPU(c, value);
	}

	ADD_EMPTY_LINE;
}