/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 2013 Gleb Smirnoff <glebius@FreeBSD.org>
 * Copyright (c) 2010 Juniper Networks, Inc.
 * Copyright (c) 2009 Robert N. M. Watson
 * Copyright (c) 2009 Bjoern A. Zeeb <bz@FreeBSD.org>
 * Copyright (c) 2008 Yahoo!, Inc.
 * All rights reserved.
 *
 * Written by: John Baldwin <jhb@FreeBSD.org>
 *
 * This software was developed by Robert N. M. Watson under contract
 * to Juniper Networks, Inc.
 *
 * 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/param.h>
#include <sys/pcpu.h>
#include <sys/sysctl.h>
#include <kvm.h>
#include <limits.h>
#include <stdlib.h>

#include "kvm_private.h"

#ifdef __amd64__
#define __OFFSET_BY_PCPU
#endif

static struct nlist kvm_pcpu_nl[] = {
        { .n_name = "_cpuid_to_pcpu" },
        { .n_name = "_mp_maxcpus" },
        { .n_name = "_mp_ncpus" },
#ifdef __OFFSET_BY_PCPU
        { .n_name = "___pcpu" },
#endif
        { .n_name = NULL },
};
#define NL_CPUID_TO_PCPU        0
#define NL_MP_MAXCPUS           1
#define NL_MP_NCPUS             2
#define NL___PCPU               3

/*
 * Kernel per-CPU data state.  We cache this stuff on the first
 * access.
 *
 * XXXRW: Possibly, this (and kvmpcpu_nl) should be per-kvm_t, in case the
 * consumer has multiple handles in flight to differently configured
 * kernels/crashdumps.
 */
static void **pcpu_data;
static int maxcpu;
static int mp_ncpus;
#ifdef __OFFSET_BY_PCPU
static unsigned long __pcpu;
#endif

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);
        }
        if (kvm_pcpu_nl[NL_MP_NCPUS].n_value == 0) {
                _kvm_err(kd, kd->program, "unable to find mp_ncpus");
                return (-1);
        }
        if (kvm_read(kd, kvm_pcpu_nl[NL_MP_NCPUS].n_value, &mp_ncpus,
            sizeof(mp_ncpus)) != sizeof(mp_ncpus)) {
                _kvm_err(kd, kd->program, "cannot read mp_ncpus");
                return (-1);
        }
#ifdef __OFFSET_BY_PCPU
        if (kvm_pcpu_nl[NL___PCPU].n_value == 0) {
                _kvm_err(kd, kd->program, "unable to find __pcpu");
                return (-1);
        }
        if (kvm_read(kd, kvm_pcpu_nl[NL___PCPU].n_value, &__pcpu,
            sizeof(__pcpu)) != sizeof(__pcpu)) {
                _kvm_err(kd, kd->program, "cannot read __pcpu");
                return (-1);
        }
#endif
        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) !=
           (ssize_t)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;

        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);
}

int
kvm_getncpus(kvm_t *kd)
{

        if (mp_ncpus == 0)
                if (_kvm_pcpu_init(kd) < 0)
                        return (-1);
        return (mp_ncpus);
}

static int
_kvm_dpcpu_setcpu(kvm_t *kd, u_int cpu, int report_error)
{

        if (!kd->dpcpu_initialized) {
                if (report_error)
                        _kvm_err(kd, kd->program, "%s: not initialized",
                            __func__);
                return (-1);
        }
        if (cpu >= kd->dpcpu_maxcpus) {
                if (report_error)
                        _kvm_err(kd, kd->program, "%s: CPU %u too big",
                            __func__, cpu);
                return (-1);
        }
        if (kd->dpcpu_off[cpu] == 0) {
                if (report_error)
                        _kvm_err(kd, kd->program, "%s: CPU %u not found",
                            __func__, cpu);
                return (-1);
        }
        kd->dpcpu_curcpu = cpu;
        kd->dpcpu_curoff = kd->dpcpu_off[cpu];
        return (0);
}

/*
 * Set up libkvm to handle dynamic per-CPU memory.
 */
static int
_kvm_dpcpu_init(kvm_t *kd)
{
        struct kvm_nlist nl[] = {
#define NLIST_START_SET_PCPU    0
                { .n_name = "___start_" DPCPU_SETNAME },
#define NLIST_STOP_SET_PCPU     1
                { .n_name = "___stop_" DPCPU_SETNAME },
#define NLIST_DPCPU_OFF         2
                { .n_name = "_dpcpu_off" },
#define NLIST_MP_MAXCPUS        3
                { .n_name = "_mp_maxcpus" },
                { .n_name = NULL },
        };
        uintptr_t *dpcpu_off_buf;
        size_t len;
        u_int dpcpu_maxcpus;

        /*
         * XXX: This only works for native kernels for now.
         */
        if (!kvm_native(kd))
                return (-1);

        /*
         * Locate and cache locations of important symbols using the internal
         * version of _kvm_nlist, turning off initialization to avoid
         * recursion in case of unresolveable symbols.
         */
        if (_kvm_nlist(kd, nl, 0) != 0)
                return (-1);
        if (kvm_read(kd, nl[NLIST_MP_MAXCPUS].n_value, &dpcpu_maxcpus,
            sizeof(dpcpu_maxcpus)) != sizeof(dpcpu_maxcpus))
                return (-1);
        len = dpcpu_maxcpus * sizeof(*dpcpu_off_buf);
        dpcpu_off_buf = malloc(len);
        if (dpcpu_off_buf == NULL)
                return (-1);
        if (kvm_read(kd, nl[NLIST_DPCPU_OFF].n_value, dpcpu_off_buf, len) !=
            (ssize_t)len) {
                free(dpcpu_off_buf);
                return (-1);
        }
        kd->dpcpu_start = nl[NLIST_START_SET_PCPU].n_value;
        kd->dpcpu_stop = nl[NLIST_STOP_SET_PCPU].n_value;
        kd->dpcpu_maxcpus = dpcpu_maxcpus;
        kd->dpcpu_off = dpcpu_off_buf;
        kd->dpcpu_initialized = 1;
        (void)_kvm_dpcpu_setcpu(kd, 0, 0);
        return (0);
}

/*
 * Check whether the dpcpu module has been initialized successfully or not,
 * initialize it if permitted.
 */
int
_kvm_dpcpu_initialized(kvm_t *kd, int intialize)
{

        if (kd->dpcpu_initialized || !intialize)
                return (kd->dpcpu_initialized);

        (void)_kvm_dpcpu_init(kd);

        return (kd->dpcpu_initialized);
}

/*
 * Check whether the value is within the dpcpu symbol range and only if so
 * adjust the offset relative to the current offset.
 */
kvaddr_t
_kvm_dpcpu_validaddr(kvm_t *kd, kvaddr_t value)
{

        if (value == 0)
                return (value);

        if (!kd->dpcpu_initialized)
                return (value);

        if (value < kd->dpcpu_start || value >= kd->dpcpu_stop)
                return (value);

        return (kd->dpcpu_curoff + value);
}

int
kvm_dpcpu_setcpu(kvm_t *kd, u_int cpu)
{
        int ret;

        if (!kd->dpcpu_initialized) {
                ret = _kvm_dpcpu_init(kd);
                if (ret != 0) {
                        _kvm_err(kd, kd->program, "%s: init failed",
                            __func__);
                        return (ret);
                }
        }

        return (_kvm_dpcpu_setcpu(kd, cpu, 1));
}

/*
 * Obtain a per-CPU copy for given cpu from UMA_ZONE_PCPU allocation.
 */
ssize_t
kvm_read_zpcpu(kvm_t *kd, u_long base, void *buf, size_t size, int cpu)
{

        if (!kvm_native(kd))
                return (-1);
        if (mp_ncpus == 0)
                if (_kvm_pcpu_init(kd) < 0)
                        return (0);

#ifdef __OFFSET_BY_PCPU
        base += __pcpu;
#endif
        return (kvm_read(kd, (uintptr_t)(base + sizeof(struct pcpu) * cpu),
            buf, size));
}

/*
 * Fetch value of a counter(9).
 */
uint64_t
kvm_counter_u64_fetch(kvm_t *kd, u_long base)
{
        uint64_t r, c;

        if (mp_ncpus == 0)
                if (_kvm_pcpu_init(kd) < 0)
                        return (0);

        r = 0;
        for (int i = 0; i < mp_ncpus; i++) {
                if (kvm_read_zpcpu(kd, base, &c, sizeof(c), i) != sizeof(c))
                        return (0);
                r += c;
        }

        return (r);
}