/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (C) 2016 Gvozden Nešković. All rights reserved.
 */

#include <sys/zfs_context.h>
#include <sys/types.h>
#include <sys/zio.h>
#include <sys/debug.h>
#include <sys/zfs_debug.h>
#include <sys/vdev_raidz.h>
#include <sys/vdev_raidz_impl.h>
#include <sys/simd.h>

#ifndef isspace
#define isspace(c)      ((c) == ' ' || (c) == '\t' || (c) == '\n' || \
                        (c) == '\r' || (c) == '\f' || (c) == '\013')
#endif

extern boolean_t raidz_will_scalar_work(void);

/* Opaque implementation with NULL methods to represent original methods */
static const raidz_impl_ops_t vdev_raidz_original_impl = {
        .name = "original",
        .is_supported = raidz_will_scalar_work,
};

/* RAIDZ parity op that contain the fastest methods */
static raidz_impl_ops_t vdev_raidz_fastest_impl = {
        .name = "fastest"
};

/* All compiled in implementations */
const raidz_impl_ops_t *raidz_all_maths[] = {
        &vdev_raidz_original_impl,
        &vdev_raidz_scalar_impl,
#if defined(__amd64)
        &vdev_raidz_sse2_impl,
        &vdev_raidz_ssse3_impl,
        &vdev_raidz_avx2_impl,
#endif
};

/* Indicate that benchmark has been completed */
static boolean_t raidz_math_initialized = B_FALSE;

/* Select raidz implementation */
#define IMPL_FASTEST    (UINT32_MAX)
#define IMPL_CYCLE      (UINT32_MAX - 1)
#define IMPL_ORIGINAL   (0)
#define IMPL_SCALAR     (1)

#define RAIDZ_IMPL_READ(i)      (*(volatile uint32_t *) &(i))

static uint32_t zfs_vdev_raidz_impl = IMPL_SCALAR;
static uint32_t user_sel_impl = IMPL_FASTEST;

/* Hold all supported implementations */
static size_t raidz_supp_impl_cnt = 0;
static raidz_impl_ops_t *raidz_supp_impl[ARRAY_SIZE(raidz_all_maths)];

#if defined(_KERNEL)
/*
 * kstats values for supported implementations
 * Values represent per disk throughput of 8 disk+parity raidz vdev [B/s]
 *
 * PORTING NOTE:
 * On illumos this is not a kstat. OpenZFS uses their home-grown kstat code
 * which implements a free-form kstat using additional functionality that does
 * not exist in illumos. Because there are no software consumers of this
 * information, we omit a kstat API. If an administrator needs to see this
 * data for some reason, they can use mdb.
 *
 * The format of the kstat data on OpenZFS would be a "header" that looks like
 * this (a column for each entry in the "raidz_gen_name" and "raidz_rec_name"
 * arrays, starting with the parity function "implementation" name):
 *     impl gen_p gen_pq gen_pqr rec_p rec_q rec_r rec_pq rec_pr rec_qr rec_pqr
 * This is followed by a row for each parity function implementation, showing
 * the "speed" values calculated for that implementation for each of the
 * parity generation and reconstruction functions in the "raidz_all_maths"
 * array.
 */
static raidz_impl_kstat_t raidz_impl_kstats[ARRAY_SIZE(raidz_all_maths) + 1];

#endif

/*
 * Returns the RAIDZ operations for raidz_map() parity calculations.   When
 * a SIMD implementation is not allowed in the current context, then fallback
 * to the fastest generic implementation.
 */
const raidz_impl_ops_t *
vdev_raidz_math_get_ops(void)
{
        if (!kfpu_allowed())
                return (&vdev_raidz_scalar_impl);

        raidz_impl_ops_t *ops = NULL;
        const uint32_t impl = RAIDZ_IMPL_READ(zfs_vdev_raidz_impl);

        switch (impl) {
        case IMPL_FASTEST:
                ASSERT(raidz_math_initialized);
                ops = &vdev_raidz_fastest_impl;
                break;
        case IMPL_CYCLE:
                /* Cycle through all supported implementations */
                ASSERT(raidz_math_initialized);
                ASSERT3U(raidz_supp_impl_cnt, >, 0);
                static size_t cycle_impl_idx = 0;
                size_t idx = (++cycle_impl_idx) % raidz_supp_impl_cnt;
                ops = raidz_supp_impl[idx];
                break;
        case IMPL_ORIGINAL:
                ops = (raidz_impl_ops_t *)&vdev_raidz_original_impl;
                break;
        case IMPL_SCALAR:
                ops = (raidz_impl_ops_t *)&vdev_raidz_scalar_impl;
                break;
        default:
                ASSERT3U(impl, <, raidz_supp_impl_cnt);
                ASSERT3U(raidz_supp_impl_cnt, >, 0);
                if (impl < ARRAY_SIZE(raidz_all_maths))
                        ops = raidz_supp_impl[impl];
                break;
        }

        ASSERT3P(ops, !=, NULL);

        return (ops);
}

/*
 * Select parity generation method for raidz_map
 */
int
vdev_raidz_math_generate(raidz_map_t *rm)
{
        raidz_gen_f gen_parity = NULL;

        switch (raidz_parity(rm)) {
                case 1:
                        gen_parity = rm->rm_ops->gen[RAIDZ_GEN_P];
                        break;
                case 2:
                        gen_parity = rm->rm_ops->gen[RAIDZ_GEN_PQ];
                        break;
                case 3:
                        gen_parity = rm->rm_ops->gen[RAIDZ_GEN_PQR];
                        break;
                default:
                        gen_parity = NULL;
                        cmn_err(CE_PANIC, "invalid RAID-Z configuration %u",
                            (uint_t)raidz_parity(rm));
                        break;
        }

        /* if method is NULL execute the original implementation */
        if (gen_parity == NULL)
                return (RAIDZ_ORIGINAL_IMPL);

        gen_parity(rm);

        return (0);
}

static raidz_rec_f
reconstruct_fun_p_sel(raidz_map_t *rm, const int *parity_valid,
    const int nbaddata)
{
        if (nbaddata == 1 && parity_valid[CODE_P]) {
                return (rm->rm_ops->rec[RAIDZ_REC_P]);
        }
        return ((raidz_rec_f) NULL);
}

static raidz_rec_f
reconstruct_fun_pq_sel(raidz_map_t *rm, const int *parity_valid,
    const int nbaddata)
{
        if (nbaddata == 1) {
                if (parity_valid[CODE_P]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_P]);
                } else if (parity_valid[CODE_Q]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_Q]);
                }
        } else if (nbaddata == 2 &&
            parity_valid[CODE_P] && parity_valid[CODE_Q]) {
                return (rm->rm_ops->rec[RAIDZ_REC_PQ]);
        }
        return ((raidz_rec_f) NULL);
}

static raidz_rec_f
reconstruct_fun_pqr_sel(raidz_map_t *rm, const int *parity_valid,
    const int nbaddata)
{
        if (nbaddata == 1) {
                if (parity_valid[CODE_P]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_P]);
                } else if (parity_valid[CODE_Q]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_Q]);
                } else if (parity_valid[CODE_R]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_R]);
                }
        } else if (nbaddata == 2) {
                if (parity_valid[CODE_P] && parity_valid[CODE_Q]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_PQ]);
                } else if (parity_valid[CODE_P] && parity_valid[CODE_R]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_PR]);
                } else if (parity_valid[CODE_Q] && parity_valid[CODE_R]) {
                        return (rm->rm_ops->rec[RAIDZ_REC_QR]);
                }
        } else if (nbaddata == 3 &&
            parity_valid[CODE_P] && parity_valid[CODE_Q] &&
            parity_valid[CODE_R]) {
                return (rm->rm_ops->rec[RAIDZ_REC_PQR]);
        }
        return ((raidz_rec_f) NULL);
}

/*
 * Select data reconstruction method for raidz_map
 * @parity_valid - Parity validity flag
 * @dt           - Failed data index array
 * @nbaddata     - Number of failed data columns
 */
int
vdev_raidz_math_reconstruct(raidz_map_t *rm, const int *parity_valid,
    const int *dt, const int nbaddata)
{
        raidz_rec_f rec_fn = NULL;

        switch (raidz_parity(rm)) {
        case PARITY_P:
                rec_fn = reconstruct_fun_p_sel(rm, parity_valid, nbaddata);
                break;
        case PARITY_PQ:
                rec_fn = reconstruct_fun_pq_sel(rm, parity_valid, nbaddata);
                break;
        case PARITY_PQR:
                rec_fn = reconstruct_fun_pqr_sel(rm, parity_valid, nbaddata);
                break;
        default:
                cmn_err(CE_PANIC, "invalid RAID-Z configuration %u",
                    (uint_t)raidz_parity(rm));
                break;
        }

        if (rec_fn == NULL)
                return (RAIDZ_ORIGINAL_IMPL);
        else
                return (rec_fn(rm, dt));
}

const char *raidz_gen_name[] = {
        "gen_p", "gen_pq", "gen_pqr"
};
const char *raidz_rec_name[] = {
        "rec_p", "rec_q", "rec_r",
        "rec_pq", "rec_pr", "rec_qr", "rec_pqr"
};

#if defined(_KERNEL)

#define BENCH_D_COLS    (8ULL)
#define BENCH_COLS      (BENCH_D_COLS + PARITY_PQR)
#define BENCH_ZIO_SIZE  (1ULL << SPA_OLD_MAXBLOCKSHIFT) /* 128 kiB */
#define BENCH_NS        MSEC2NSEC(1)                    /* 1ms */

typedef void (*benchmark_fn)(raidz_map_t *rm, const int fn);

static void
benchmark_gen_impl(raidz_map_t *rm, const int fn)
{
        (void) fn;
        vdev_raidz_generate_parity(rm);
}

static void
benchmark_rec_impl(raidz_map_t *rm, const int fn)
{
        static const int rec_tgt[7][3] = {
                {1, 2, 3},      /* rec_p:   bad QR & D[0]       */
                {0, 2, 3},      /* rec_q:   bad PR & D[0]       */
                {0, 1, 3},      /* rec_r:   bad PQ & D[0]       */
                {2, 3, 4},      /* rec_pq:  bad R  & D[0][1]    */
                {1, 3, 4},      /* rec_pr:  bad Q  & D[0][1]    */
                {0, 3, 4},      /* rec_qr:  bad P  & D[0][1]    */
                {3, 4, 5}       /* rec_pqr: bad    & D[0][1][2] */
        };

        vdev_raidz_reconstruct(rm, rec_tgt[fn], 3);
}

/*
 * Benchmarking of all supported implementations (raidz_supp_impl_cnt)
 * is performed by setting the rm_ops pointer and calling the top level
 * generate/reconstruct methods of bench_rm.
 */
static void
benchmark_raidz_impl(raidz_map_t *bench_rm, const int fn, benchmark_fn bench_fn)
{
        uint64_t run_cnt, speed, best_speed = 0;
        hrtime_t t_start, t_diff;
        raidz_impl_ops_t *curr_impl;
        raidz_impl_kstat_t *fstat = &raidz_impl_kstats[raidz_supp_impl_cnt];
        int impl, i;

        for (impl = 0; impl < raidz_supp_impl_cnt; impl++) {
                /* set an implementation to benchmark */
                curr_impl = raidz_supp_impl[impl];
                bench_rm->rm_ops = curr_impl;

                run_cnt = 0;
                t_start = gethrtime();

                do {
                        for (i = 0; i < 5; i++, run_cnt++)
                                bench_fn(bench_rm, fn);

                        t_diff = gethrtime() - t_start;
                } while (t_diff < BENCH_NS);

                speed = run_cnt * BENCH_ZIO_SIZE * NANOSEC;
                speed /= (t_diff * BENCH_COLS);

                if (bench_fn == benchmark_gen_impl)
                        raidz_impl_kstats[impl].gen[fn] = speed;
                else
                        raidz_impl_kstats[impl].rec[fn] = speed;

                /* Update fastest implementation method */
                if (speed > best_speed) {
                        best_speed = speed;

                        if (bench_fn == benchmark_gen_impl) {
                                fstat->gen[fn] = impl;
                                vdev_raidz_fastest_impl.gen[fn] =
                                    curr_impl->gen[fn];
                        } else {
                                fstat->rec[fn] = impl;
                                vdev_raidz_fastest_impl.rec[fn] =
                                    curr_impl->rec[fn];
                        }
                }
        }
}
#endif

/*
 * Initialize and benchmark all supported implementations.
 */
static void
benchmark_raidz(void)
{
        raidz_impl_ops_t *curr_impl;
        int i, c;

        /* Move supported impl into raidz_supp_impl */
        for (i = 0, c = 0; i < ARRAY_SIZE(raidz_all_maths); i++) {
                curr_impl = (raidz_impl_ops_t *)raidz_all_maths[i];

                if (curr_impl->init)
                        curr_impl->init();

                if (curr_impl->is_supported())
                        raidz_supp_impl[c++] = (raidz_impl_ops_t *)curr_impl;
        }
        membar_producer();              /* complete raidz_supp_impl[] init */
        raidz_supp_impl_cnt = c;        /* number of supported impl */

#if defined(_KERNEL)
        zio_t *bench_zio = NULL;
        raidz_map_t *bench_rm = NULL;
        uint64_t bench_parity;

        /* Fake a zio and run the benchmark on a warmed up buffer */
        bench_zio = kmem_zalloc(sizeof (zio_t), KM_SLEEP);
        bench_zio->io_offset = 0;
        bench_zio->io_size = BENCH_ZIO_SIZE; /* only data columns */
        bench_zio->io_abd = abd_alloc_linear(BENCH_ZIO_SIZE, B_TRUE);
        memset(abd_to_buf(bench_zio->io_abd), 0xAA, BENCH_ZIO_SIZE);

        /* Benchmark parity generation methods */
        for (int fn = 0; fn < RAIDZ_GEN_NUM; fn++) {
                bench_parity = fn + 1;
                /* New raidz_map is needed for each generate_p/q/r */
                bench_rm = vdev_raidz_map_alloc(bench_zio, SPA_MINBLOCKSHIFT,
                    BENCH_D_COLS + bench_parity, bench_parity);

                benchmark_raidz_impl(bench_rm, fn, benchmark_gen_impl);

                vdev_raidz_map_free(bench_rm);
        }

        /* Benchmark data reconstruction methods */
        bench_rm = vdev_raidz_map_alloc(bench_zio, SPA_MINBLOCKSHIFT,
            BENCH_COLS, PARITY_PQR);

        for (int fn = 0; fn < RAIDZ_REC_NUM; fn++)
                benchmark_raidz_impl(bench_rm, fn, benchmark_rec_impl);

        vdev_raidz_map_free(bench_rm);

        /* cleanup the bench zio */
        abd_free(bench_zio->io_abd);
        kmem_free(bench_zio, sizeof (zio_t));
#else
        /*
         * Skip the benchmark in user space to avoid impacting libzpool
         * consumers (zdb, zhack, zinject, ztest).  The last implementation
         * is assumed to be the fastest and used by default.
         */
        memcpy(&vdev_raidz_fastest_impl,
            raidz_supp_impl[raidz_supp_impl_cnt - 1],
            sizeof (vdev_raidz_fastest_impl));
        strcpy(vdev_raidz_fastest_impl.name, "fastest");
#endif /* _KERNEL */
}

void
vdev_raidz_math_init(void)
{
        /* Determine the fastest available implementation. */
        benchmark_raidz();

        /* Finish initialization */
        atomic_swap_32(&zfs_vdev_raidz_impl, user_sel_impl);
        raidz_math_initialized = B_TRUE;
}

void
vdev_raidz_math_fini(void)
{
        raidz_impl_ops_t const *curr_impl;

        for (int i = 0; i < ARRAY_SIZE(raidz_all_maths); i++) {
                curr_impl = raidz_all_maths[i];
                if (curr_impl->fini)
                        curr_impl->fini();
        }
}

static const struct {
        char *name;
        uint32_t sel;
} math_impl_opts[] = {
                { "cycle",      IMPL_CYCLE },
                { "fastest",    IMPL_FASTEST },
                { "original",   IMPL_ORIGINAL },
                { "scalar",     IMPL_SCALAR }
};

/*
 * Function sets desired raidz implementation.
 *
 * If we are called before init(), user preference will be saved in
 * user_sel_impl, and applied in later init() call. This occurs when module
 * parameter is specified on module load. Otherwise, directly update
 * zfs_vdev_raidz_impl.
 *
 * @val         Name of raidz implementation to use
 * @param       Unused.
 */
int
vdev_raidz_impl_set(const char *val)
{
        int err = EINVAL;
        char req_name[RAIDZ_IMPL_NAME_MAX];
        uint32_t impl = RAIDZ_IMPL_READ(user_sel_impl);
        size_t i;

        /* sanitize input */
        i = strnlen(val, RAIDZ_IMPL_NAME_MAX);
        if (i == 0 || i == RAIDZ_IMPL_NAME_MAX)
                return (err);

        strlcpy(req_name, val, RAIDZ_IMPL_NAME_MAX);
        while (i > 0 && !!isspace(req_name[i-1]))
                i--;
        req_name[i] = '\0';

        /* Check mandatory options */
        for (i = 0; i < ARRAY_SIZE(math_impl_opts); i++) {
                if (strcmp(req_name, math_impl_opts[i].name) == 0) {
                        impl = math_impl_opts[i].sel;
                        err = 0;
                        break;
                }
        }

        /* check all supported impl if init() was already called */
        if (err != 0 && raidz_math_initialized) {
                /* check all supported implementations */
                for (i = 0; i < raidz_supp_impl_cnt; i++) {
                        if (strcmp(req_name, raidz_supp_impl[i]->name) == 0) {
                                impl = i;
                                err = 0;
                                break;
                        }
                }
        }

        if (err == 0) {
                if (raidz_math_initialized)
                        atomic_swap_32(&zfs_vdev_raidz_impl, impl);
                else
                        atomic_swap_32(&user_sel_impl, impl);
        }

        return (err);
}

#if defined(_KERNEL) && defined(__linux__)

static int
zfs_vdev_raidz_impl_set(const char *val, zfs_kernel_param_t *kp)
{
        return (vdev_raidz_impl_set(val));
}

static int
zfs_vdev_raidz_impl_get(char *buffer, zfs_kernel_param_t *kp)
{
        int i, cnt = 0;
        char *fmt;
        const uint32_t impl = RAIDZ_IMPL_READ(zfs_vdev_raidz_impl);

        ASSERT(raidz_math_initialized);

        /* list mandatory options */
        for (i = 0; i < ARRAY_SIZE(math_impl_opts) - 2; i++) {
                fmt = (impl == math_impl_opts[i].sel) ? "[%s] " : "%s ";
                cnt += sprintf(buffer + cnt, fmt, math_impl_opts[i].name);
        }

        /* list all supported implementations */
        for (i = 0; i < raidz_supp_impl_cnt; i++) {
                fmt = (i == impl) ? "[%s] " : "%s ";
                cnt += sprintf(buffer + cnt, fmt, raidz_supp_impl[i]->name);
        }

        return (cnt);
}

module_param_call(zfs_vdev_raidz_impl, zfs_vdev_raidz_impl_set,
    zfs_vdev_raidz_impl_get, NULL, 0644);
MODULE_PARM_DESC(zfs_vdev_raidz_impl, "Select raidz implementation.");
#endif