/*-
 * 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.
 */

/* Hardware Trace (HWT) framework. */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mutex.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_backend.h>

#define HWT_BACKEND_DEBUG
#undef  HWT_BACKEND_DEBUG

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

static struct mtx hwt_backend_mtx;

struct hwt_backend_entry {
        struct hwt_backend *backend;
        LIST_ENTRY(hwt_backend_entry) next;
};

static LIST_HEAD(, hwt_backend_entry)   hwt_backends;

static MALLOC_DEFINE(M_HWT_BACKEND, "hwt_backend", "HWT backend");

int
hwt_backend_init(struct hwt_context *ctx)
{
        int error;

        dprintf("%s\n", __func__);

        error = ctx->hwt_backend->ops->hwt_backend_init(ctx);

        return (error);
}

void
hwt_backend_deinit(struct hwt_context *ctx)
{

        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_deinit(ctx);
}

int
hwt_backend_configure(struct hwt_context *ctx, int cpu_id, int thread_id)
{
        int error;

        dprintf("%s\n", __func__);

        error = ctx->hwt_backend->ops->hwt_backend_configure(ctx, cpu_id,
            thread_id);

        return (error);
}

void
hwt_backend_enable(struct hwt_context *ctx, int cpu_id)
{

        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_enable(ctx, cpu_id);
}

void
hwt_backend_disable(struct hwt_context *ctx, int cpu_id)
{

        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_disable(ctx, cpu_id);
}

void
hwt_backend_enable_smp(struct hwt_context *ctx)
{

        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_enable_smp(ctx);
}

void
hwt_backend_disable_smp(struct hwt_context *ctx)
{

        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_disable_smp(ctx);
}

void __unused
hwt_backend_dump(struct hwt_context *ctx, int cpu_id)
{

        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_dump(cpu_id);
}

int
hwt_backend_read(struct hwt_context *ctx, struct hwt_vm *vm, int *ident,
    vm_offset_t *offset, uint64_t *data)
{
        int error;

        dprintf("%s\n", __func__);

        error = ctx->hwt_backend->ops->hwt_backend_read(vm, ident,
            offset, data);

        return (error);
}

struct hwt_backend *
hwt_backend_lookup(const char *name)
{
        struct hwt_backend_entry *entry;
        struct hwt_backend *backend;

        HWT_BACKEND_LOCK();
        LIST_FOREACH(entry, &hwt_backends, next) {
                backend = entry->backend;
                if (strcmp(backend->name, name) == 0) {
                        HWT_BACKEND_UNLOCK();
                        return (backend);
                }
        }
        HWT_BACKEND_UNLOCK();

        return (NULL);
}

int
hwt_backend_register(struct hwt_backend *backend)
{
        struct hwt_backend_entry *entry;

        if (backend == NULL ||
            backend->name == NULL ||
            backend->ops == NULL)
                return (EINVAL);

        entry = malloc(sizeof(struct hwt_backend_entry), M_HWT_BACKEND,
            M_WAITOK | M_ZERO);
        entry->backend = backend;

        HWT_BACKEND_LOCK();
        LIST_INSERT_HEAD(&hwt_backends, entry, next);
        HWT_BACKEND_UNLOCK();

        return (0);
}

int
hwt_backend_unregister(struct hwt_backend *backend)
{
        struct hwt_backend_entry *entry, *tmp;

        if (backend == NULL)
                return (EINVAL);

        /* TODO: check if not in use */

        HWT_BACKEND_LOCK();
        LIST_FOREACH_SAFE(entry, &hwt_backends, next, tmp) {
                if (entry->backend == backend) {
                        LIST_REMOVE(entry, next);
                        HWT_BACKEND_UNLOCK();
                        free(entry, M_HWT_BACKEND);
                        return (0);
                }
        }
        HWT_BACKEND_UNLOCK();

        return (ENOENT);
}

void
hwt_backend_load(void)
{

        mtx_init(&hwt_backend_mtx, "hwt backend", NULL, MTX_DEF);
        LIST_INIT(&hwt_backends);
}

void
hwt_backend_unload(void)
{

        /* TODO: ensure all unregistered */

        mtx_destroy(&hwt_backend_mtx);
}

void
hwt_backend_stop(struct hwt_context *ctx)
{
        dprintf("%s\n", __func__);

        ctx->hwt_backend->ops->hwt_backend_stop(ctx);
}

int
hwt_backend_svc_buf(struct hwt_context *ctx, void *data, size_t data_size,
    int data_version)
{
        int error;

        dprintf("%s\n", __func__);

        error = ctx->hwt_backend->ops->hwt_backend_svc_buf(ctx, data, data_size,
            data_version);

        return (error);
}

int
hwt_backend_thread_alloc(struct hwt_context *ctx, struct hwt_thread *thr)
{
        int error;

        dprintf("%s\n", __func__);

        if (ctx->hwt_backend->ops->hwt_backend_thread_alloc == NULL)
                return (0);
        KASSERT(thr->private == NULL,
                    ("%s: thread private data is not NULL\n", __func__));
        error = ctx->hwt_backend->ops->hwt_backend_thread_alloc(thr);

        return (error);
}

void
hwt_backend_thread_free(struct hwt_thread *thr)
{
        dprintf("%s\n", __func__);

        if (thr->backend->ops->hwt_backend_thread_free == NULL)
                return;
        KASSERT(thr->private != NULL,
                    ("%s: thread private data is NULL\n", __func__));
        thr->backend->ops->hwt_backend_thread_free(thr);

        return;
}