/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2023-2025 Ruslan Bukin <br@bsdpad.com>
 *
 * This work was supported by Innovate UK project 105694, "Digital Security
 * by Design (DSbD) Technology Platform Prototype".
 *
 * 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.
 *
 * 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/bitstring.h>
#include <sys/conf.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/mutex.h>
#include <sys/refcount.h>
#include <sys/rwlock.h>
#include <sys/hwt.h>

#include <dev/hwt/hwt_hook.h>
#include <dev/hwt/hwt_context.h>
#include <dev/hwt/hwt_config.h>
#include <dev/hwt/hwt_thread.h>
#include <dev/hwt/hwt_owner.h>
#include <dev/hwt/hwt_vm.h>
#include <dev/hwt/hwt_cpu.h>

#define HWT_DEBUG
#undef  HWT_DEBUG

#ifdef  HWT_DEBUG
#define dprintf(fmt, ...)       printf(fmt, ##__VA_ARGS__)
#else
#define dprintf(fmt, ...)
#endif

static MALLOC_DEFINE(M_HWT_CTX, "hwt_ctx", "Hardware Trace");

static bitstr_t *ident_set;
static int ident_set_size;
static struct mtx ident_set_mutex;

static int
hwt_ctx_ident_alloc(int *new_ident)
{

        mtx_lock(&ident_set_mutex);
        bit_ffc(ident_set, ident_set_size, new_ident);
        if (*new_ident == -1) {
                mtx_unlock(&ident_set_mutex);
                return (ENOMEM);
        }
        bit_set(ident_set, *new_ident);
        mtx_unlock(&ident_set_mutex);

        return (0);
}

static void
hwt_ctx_ident_free(int ident)
{

        mtx_lock(&ident_set_mutex);
        bit_clear(ident_set, ident);
        mtx_unlock(&ident_set_mutex);
}

int
hwt_ctx_alloc(struct hwt_context **ctx0)
{
        struct hwt_context *ctx;
        int error;

        ctx = malloc(sizeof(struct hwt_context), M_HWT_CTX, M_WAITOK | M_ZERO);

        TAILQ_INIT(&ctx->records);
        TAILQ_INIT(&ctx->threads);
        TAILQ_INIT(&ctx->cpus);
        mtx_init(&ctx->mtx, "ctx", NULL, MTX_SPIN);
        mtx_init(&ctx->rec_mtx, "ctx_rec", NULL, MTX_DEF);
        refcount_init(&ctx->refcnt, 0);

        error = hwt_ctx_ident_alloc(&ctx->ident);
        if (error) {
                printf("could not allocate ident bit str\n");
                return (error);
        }

        *ctx0 = ctx;

        return (0);
}

static void
hwt_ctx_free_cpus(struct hwt_context *ctx)
{
        struct hwt_cpu *cpu;

        do {
                HWT_CTX_LOCK(ctx);
                cpu = TAILQ_FIRST(&ctx->cpus);
                if (cpu)
                        TAILQ_REMOVE(&ctx->cpus, cpu, next);
                HWT_CTX_UNLOCK(ctx);

                if (cpu == NULL)
                        break;

                /* TODO: move vm_free() to cpu_free()? */
                hwt_vm_free(cpu->vm);
                hwt_cpu_free(cpu);
        } while (1);
}

static void
hwt_ctx_free_threads(struct hwt_context *ctx)
{
        struct hwt_thread *thr;

        dprintf("%s: remove threads\n", __func__);

        do {
                HWT_CTX_LOCK(ctx);
                thr = TAILQ_FIRST(&ctx->threads);
                if (thr)
                        TAILQ_REMOVE(&ctx->threads, thr, next);
                HWT_CTX_UNLOCK(ctx);

                if (thr == NULL)
                        break;

                HWT_THR_LOCK(thr);
                /* TODO: check if thr is sleeping before waking it up. */
                wakeup(thr);
                HWT_THR_UNLOCK(thr);

                if (refcount_release(&thr->refcnt))
                        hwt_thread_free(thr);
        } while (1);
}

void
hwt_ctx_free(struct hwt_context *ctx)
{

        if (ctx->mode == HWT_MODE_CPU)
                hwt_ctx_free_cpus(ctx);
        else
                hwt_ctx_free_threads(ctx);

        hwt_config_free(ctx);
        hwt_ctx_ident_free(ctx->ident);
        free(ctx, M_HWT_CTX);
}

void
hwt_ctx_put(struct hwt_context *ctx)
{

        refcount_release(&ctx->refcnt);
}

void
hwt_ctx_load(void)
{

        ident_set_size = (1 << 8);
        ident_set = bit_alloc(ident_set_size, M_HWT_CTX, M_WAITOK);
        mtx_init(&ident_set_mutex, "ident set", NULL, MTX_DEF);
}

void
hwt_ctx_unload(void)
{

        mtx_destroy(&ident_set_mutex);
        free(ident_set, M_HWT_CTX);
}