Add two new routines to libkvm for working with per-CPU data:

kvm_getmaxcpu() and kvm_getpcpu().

MFC after:	1 week

1 files changed, 152 insertions, 0 deletions

diff --git a/lib/libkvm/kvm_pcpu.c b/lib/libkvm/kvm_pcpu.c
new file mode 100644
index 0000000..e4f8909
--- /dev/null
+++ b/lib/libkvm/kvm_pcpu.c
@@ -0,0 +1,152 @@
+/*-
+ * Copyright (c) 2008 Yahoo!, Inc.
+ * All rights reserved.
+ * Written by: John Baldwin <jhb@FreeBSD.org>
+ *
+ * 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.
+ * 3. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 CONTRIBUTORS 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/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/pcpu.h>
+#include <sys/sysctl.h>
+#include <kvm.h>
+#include <limits.h>
+#include <stdlib.h>
+
+#include "kvm_private.h"
+
+static struct nlist kvm_pcpu_nl[] = {
+	{ "_cpuid_to_pcpu" },
+	{ "_mp_maxcpus" },
+	{ NULL },
+};
+
+/*
+ * Kernel per-CPU data state.  We cache this stuff on the first
+ * access.	
+ */
+static void **pcpu_data;
+static int maxcpu;
+
+#define	NL_CPUID_TO_PCPU	0
+#define	NL_MP_MAXCPUS		1
+
+static int
+_kvm_pcpu_init(kvm_t *kd)
+{
+	size_t len;
+	int max;
+	void *data;
+
+	if (kvm_nlist(kd, kvm_pcpu_nl) < 0)
+		return (-1);
+	if (kvm_pcpu_nl[NL_CPUID_TO_PCPU].n_value == 0) {
+		_kvm_err(kd, kd->program, "unable to find cpuid_to_pcpu");
+		return (-1);
+	}
+	if (kvm_pcpu_nl[NL_MP_MAXCPUS].n_value == 0) {
+		_kvm_err(kd, kd->program, "unable to find mp_maxcpus");
+		return (-1);
+	}
+	if (kvm_read(kd, kvm_pcpu_nl[NL_MP_MAXCPUS].n_value, &max,
+	    sizeof(max)) != sizeof(max)) {
+		_kvm_err(kd, kd->program, "cannot read mp_maxcpus");
+		return (-1);
+	}
+	len = max * sizeof(void *);
+	data = malloc(len);
+	if (data == NULL) {
+		_kvm_err(kd, kd->program, "out of memory");
+		return (-1);
+	}
+	if (kvm_read(kd, kvm_pcpu_nl[NL_CPUID_TO_PCPU].n_value, data, len) !=
+	    len) {
+		_kvm_err(kd, kd->program, "cannot read cpuid_to_pcpu array");
+		free(data);
+		return (-1);
+	}
+	pcpu_data = data;
+	maxcpu = max;
+	return (0);
+}
+
+static void
+_kvm_pcpu_clear(void)
+{
+
+	maxcpu = 0;
+	free(pcpu_data);
+	pcpu_data = NULL;
+}
+
+void *
+kvm_getpcpu(kvm_t *kd, int cpu)
+{
+	char *buf;
+	int i;
+
+	if (kd == NULL) {
+		_kvm_pcpu_clear();
+		return (NULL);
+	}
+
+	if (maxcpu == 0)
+		if (_kvm_pcpu_init(kd) < 0)
+			return ((void *)-1);
+
+	if (cpu >= maxcpu || pcpu_data[cpu] == NULL)
+		return (NULL);
+
+	buf = malloc(sizeof(struct pcpu));
+	if (buf == NULL) {
+		_kvm_err(kd, kd->program, "out of memory");
+		return ((void *)-1);
+	}
+	if (kvm_read(kd, (uintptr_t)pcpu_data[cpu], buf, sizeof(struct pcpu)) !=
+	    sizeof(struct pcpu)) {
+		_kvm_err(kd, kd->program, "unable to read per-CPU data");
+		free(buf);
+		return ((void *)-1);
+	}
+	return (buf);
+}
+
+int
+kvm_getmaxcpu(kvm_t *kd)
+{
+
+	if (kd == NULL) {
+		_kvm_pcpu_clear();
+		return (0);
+	}
+
+	if (maxcpu == 0)
+		if (_kvm_pcpu_init(kd) < 0)
+			return (-1);
+	return (maxcpu);
+}