freebsd-dev/lib/libkvm/kvm_getloadavg.c
Michał Górny 8099a35446 libkvm: Fix kvm_getloadavg() on modern kernel vmcores
Fix kvm_getloadavg() to work correctly on vmcores for modern kernel
versions.  The kernels no longer include the `_fscale` symbol causing
the kvm_nlist() invocation to fail.  The code seemed to already assume
that `_fscale` could be missing but the early kvm_nlist() result check
has caused the function to fail if any symbol were missing.  Modify
it to only treat `_averunnable` as obligatory, and handle missing
`_fscale` gracefully.

Sponsored by:   The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D32884
2021-12-07 15:36:34 -08:00

102 lines
3.2 KiB
C

/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1993
* The Regents of the University of California. All rights reserved.
*
* 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 University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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("$FreeBSD$");
__SCCSID("@(#)kvm_getloadavg.c 8.1 (Berkeley) 6/4/93");
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <stdlib.h>
#include <limits.h>
#include <nlist.h>
#include <kvm.h>
#include "kvm_private.h"
static struct nlist nl[] = {
{ .n_name = "_averunnable" },
#define X_AVERUNNABLE 0
{ .n_name = "_fscale" },
#define X_FSCALE 1
{ .n_name = "" },
};
/*
* kvm_getloadavg() -- Get system load averages, from live or dead kernels.
*
* Put `nelem' samples into `loadavg' array.
* Return number of samples retrieved, or -1 on error.
*/
int
kvm_getloadavg(kvm_t *kd, double loadavg[], int nelem)
{
struct loadavg loadinfo;
int fscale, i;
if (ISALIVE(kd))
return (getloadavg(loadavg, nelem));
if (!kd->arch->ka_native(kd)) {
_kvm_err(kd, kd->program,
"cannot read loadavg from non-native core");
return (-1);
}
if (kvm_nlist(kd, nl) != 0 && nl[X_AVERUNNABLE].n_type == 0) {
_kvm_err(kd, kd->program,
"%s: no such symbol", nl[X_AVERUNNABLE].n_name);
return (-1);
}
#define KREAD(kd, addr, obj) \
(kvm_read(kd, addr, (char *)(obj), sizeof(*obj)) != sizeof(*obj))
if (KREAD(kd, nl[X_AVERUNNABLE].n_value, &loadinfo)) {
_kvm_err(kd, kd->program, "can't read averunnable");
return (-1);
}
/*
* Old kernels have fscale separately; if not found assume
* running new format.
*/
if (nl[X_FSCALE].n_type != 0 &&
!KREAD(kd, nl[X_FSCALE].n_value, &fscale))
loadinfo.fscale = fscale;
nelem = MIN(nelem, (int)(sizeof(loadinfo.ldavg) / sizeof(fixpt_t)));
for (i = 0; i < nelem; i++)
loadavg[i] = (double) loadinfo.ldavg[i] / loadinfo.fscale;
return (nelem);
}