/*      $OpenBSD: subr_percpu.c,v 1.11 2023/09/16 09:33:27 mpi Exp $ */

/*
 * Copyright (c) 2016 David Gwynne <dlg@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.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/pool.h>
#include <sys/malloc.h>

#include <sys/percpu.h>

#ifdef MULTIPROCESSOR
struct pool cpumem_pl;

void
percpu_init(void)
{
        pool_init(&cpumem_pl, sizeof(struct cpumem) * ncpusfound, 0,
            IPL_NONE, PR_WAITOK, "percpumem", &pool_allocator_single);
}

struct cpumem *
cpumem_get(struct pool *pp)
{
        struct cpumem *cm;
        unsigned int cpu;

        cm = pool_get(&cpumem_pl, PR_WAITOK);

        for (cpu = 0; cpu < ncpusfound; cpu++)
                cm[cpu].mem = pool_get(pp, PR_WAITOK | PR_ZERO);

        return (cm);
}

void
cpumem_put(struct pool *pp, struct cpumem *cm)
{
        unsigned int cpu;

        for (cpu = 0; cpu < ncpusfound; cpu++)
                pool_put(pp, cm[cpu].mem);

        pool_put(&cpumem_pl, cm);
}

struct cpumem *
cpumem_malloc(size_t sz, int type)
{
        struct cpumem *cm;
        unsigned int cpu;

        sz = roundup(sz, CACHELINESIZE);

        cm = pool_get(&cpumem_pl, PR_WAITOK);

        for (cpu = 0; cpu < ncpusfound; cpu++)
                cm[cpu].mem = malloc(sz, type, M_WAITOK | M_ZERO);

        return (cm);
}

struct cpumem *
cpumem_malloc_ncpus(struct cpumem *bootcm, size_t sz, int type)
{
        struct cpumem *cm;
        unsigned int cpu;

        sz = roundup(sz, CACHELINESIZE);

        cm = pool_get(&cpumem_pl, PR_WAITOK);

        cm[0].mem = bootcm[0].mem;
        for (cpu = 1; cpu < ncpusfound; cpu++)
                cm[cpu].mem = malloc(sz, type, M_WAITOK | M_ZERO);

        return (cm);
}

void
cpumem_free(struct cpumem *cm, int type, size_t sz)
{
        unsigned int cpu;

        sz = roundup(sz, CACHELINESIZE);

        for (cpu = 0; cpu < ncpusfound; cpu++)
                free(cm[cpu].mem, type, sz);

        pool_put(&cpumem_pl, cm);
}

void *
cpumem_first(struct cpumem_iter *i, struct cpumem *cm)
{
        i->cpu = 0;

        return (cm[0].mem);
}

void *
cpumem_next(struct cpumem_iter *i, struct cpumem *cm)
{
        unsigned int cpu = ++i->cpu;

        if (cpu >= ncpusfound)
                return (NULL);

        return (cm[cpu].mem);
}

struct cpumem *
counters_alloc(unsigned int n)
{
        struct cpumem *cm;
        struct cpumem_iter cmi;
        uint64_t *counters;
        unsigned int i;

        KASSERT(n > 0);

        n++; /* add space for a generation number */
        cm = cpumem_malloc(n * sizeof(uint64_t), M_COUNTERS);

        CPUMEM_FOREACH(counters, &cmi, cm) {
                for (i = 0; i < n; i++)
                        counters[i] = 0;
        }

        return (cm);
}

struct cpumem *
counters_alloc_ncpus(struct cpumem *cm, unsigned int n)
{
        n++; /* the generation number */
        return (cpumem_malloc_ncpus(cm, n * sizeof(uint64_t), M_COUNTERS));
}

void
counters_free(struct cpumem *cm, unsigned int n)
{
        n++; /* generation number */
        cpumem_free(cm, M_COUNTERS, n * sizeof(uint64_t));
}

void
counters_read(struct cpumem *cm, uint64_t *output, unsigned int n,
    uint64_t *scratch)
{
        struct cpumem_iter cmi;
        uint64_t *gen, *counters, *temp = scratch;
        uint64_t enter, leave;
        unsigned int i;

        for (i = 0; i < n; i++)
                output[i] = 0;

        if (scratch == NULL)
                temp = mallocarray(n, sizeof(uint64_t), M_TEMP, M_WAITOK);

        gen = cpumem_first(&cmi, cm);
        do {
                counters = gen + 1;

                enter = *gen;
                for (;;) {
                        /* the generation number is odd during an update */
                        while (enter & 1) {
                                yield();
                                enter = *gen;
                        }

                        membar_consumer();
                        for (i = 0; i < n; i++)
                                temp[i] = counters[i];

                        membar_consumer();
                        leave = *gen;

                        if (enter == leave)
                                break;

                        enter = leave;
                }

                for (i = 0; i < n; i++)
                        output[i] += temp[i];

                gen = cpumem_next(&cmi, cm);
        } while (gen != NULL);

        if (scratch == NULL)
                free(temp, M_TEMP, n * sizeof(uint64_t));
}

void
counters_zero(struct cpumem *cm, unsigned int n)
{
        struct cpumem_iter cmi;
        uint64_t *counters;
        unsigned int i;

        counters = cpumem_first(&cmi, cm);
        membar_producer();
        do {
                for (i = 0; i < n; i++)
                        counters[i] = 0;
                /* zero the generation numbers too */
                membar_producer();
                counters[i] = 0;

                counters = cpumem_next(&cmi, cm);
        } while (counters != NULL);
}

#else /* MULTIPROCESSOR */

/*
 * Uniprocessor implementation of per-CPU data structures.
 *
 * UP percpu memory is a single memory allocation cast to/from the
 * cpumem struct. It is not scaled up to the size of cacheline because
 * there's no other cache to contend with.
 */

void
percpu_init(void)
{
        /* nop */
}

struct cpumem *
cpumem_get(struct pool *pp)
{
        return (pool_get(pp, PR_WAITOK | PR_ZERO));
}

void
cpumem_put(struct pool *pp, struct cpumem *cm)
{
        pool_put(pp, cm);
}

struct cpumem *
cpumem_malloc(size_t sz, int type)
{
        return (malloc(sz, type, M_WAITOK | M_ZERO));
}

struct cpumem *
cpumem_malloc_ncpus(struct cpumem *cm, size_t sz, int type)
{
        return (cm);
}

void
cpumem_free(struct cpumem *cm, int type, size_t sz)
{
        free(cm, type, sz);
}

void *
cpumem_first(struct cpumem_iter *i, struct cpumem *cm)
{
        return (cm);
}

void *
cpumem_next(struct cpumem_iter *i, struct cpumem *cm)
{
        return (NULL);
}

struct cpumem *
counters_alloc(unsigned int n)
{
        KASSERT(n > 0);

        return (cpumem_malloc(n * sizeof(uint64_t), M_COUNTERS));
}

struct cpumem *
counters_alloc_ncpus(struct cpumem *cm, unsigned int n)
{
        /* this is unnecessary, but symmetrical */
        return (cpumem_malloc_ncpus(cm, n * sizeof(uint64_t), M_COUNTERS));
}

void
counters_free(struct cpumem *cm, unsigned int n)
{
        cpumem_free(cm, M_COUNTERS, n * sizeof(uint64_t));
}

void
counters_read(struct cpumem *cm, uint64_t *output, unsigned int n,
    uint64_t *scratch)
{
        uint64_t *counters;
        unsigned int i;
        int s;

        counters = (uint64_t *)cm;

        s = splhigh();
        for (i = 0; i < n; i++)
                output[i] = counters[i];
        splx(s);
}

void
counters_zero(struct cpumem *cm, unsigned int n)
{
        uint64_t *counters;
        unsigned int i;
        int s;

        counters = (uint64_t *)cm;

        s = splhigh();
        for (i = 0; i < n; i++)
                counters[i] = 0;
        splx(s);
}

#endif /* MULTIPROCESSOR */