// SPDX-License-Identifier: GPL-2.0
/*
 * Hypervisor filesystem for Linux on s390 - debugfs interface
 *
 * Copyright IBM Corp. 2010
 * Author(s): Michael Holzheu <holzheu@linux.vnet.ibm.com>
 */

#include <linux/security.h>
#include <linux/slab.h>
#include "hypfs.h"

static struct dentry *dbfs_dir;

static struct hypfs_dbfs_data *hypfs_dbfs_data_alloc(struct hypfs_dbfs_file *f)
{
        struct hypfs_dbfs_data *data;

        data = kmalloc_obj(*data);
        if (!data)
                return NULL;
        data->dbfs_file = f;
        return data;
}

static void hypfs_dbfs_data_free(struct hypfs_dbfs_data *data)
{
        data->dbfs_file->data_free(data->buf_free_ptr);
        kfree(data);
}

static ssize_t dbfs_read(struct file *file, char __user *buf,
                         size_t size, loff_t *ppos)
{
        struct hypfs_dbfs_data *data;
        struct hypfs_dbfs_file *df;
        ssize_t rc;

        if (*ppos != 0)
                return 0;

        df = file_inode(file)->i_private;
        if (mutex_lock_interruptible(&df->lock))
                return -ERESTARTSYS;

        data = hypfs_dbfs_data_alloc(df);
        if (!data) {
                mutex_unlock(&df->lock);
                return -ENOMEM;
        }
        rc = df->data_create(&data->buf, &data->buf_free_ptr, &data->size);
        if (rc) {
                mutex_unlock(&df->lock);
                kfree(data);
                return rc;
        }
        mutex_unlock(&df->lock);

        rc = simple_read_from_buffer(buf, size, ppos, data->buf, data->size);
        hypfs_dbfs_data_free(data);
        return rc;
}

static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct hypfs_dbfs_file *df = file_inode(file)->i_private;
        long rc;

        mutex_lock(&df->lock);
        rc = df->unlocked_ioctl(file, cmd, arg);
        mutex_unlock(&df->lock);
        return rc;
}

static const struct file_operations dbfs_ops_ioctl = {
        .read           = dbfs_read,
        .unlocked_ioctl = dbfs_ioctl,
};

static const struct file_operations dbfs_ops = {
        .read           = dbfs_read,
};

void hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)
{
        const struct file_operations *fops = &dbfs_ops;

        if (df->unlocked_ioctl && !security_locked_down(LOCKDOWN_DEBUGFS))
                fops = &dbfs_ops_ioctl;
        df->dentry = debugfs_create_file(df->name, 0400, dbfs_dir, df, fops);
        mutex_init(&df->lock);
}

void hypfs_dbfs_remove_file(struct hypfs_dbfs_file *df)
{
        debugfs_remove(df->dentry);
}

static int __init hypfs_dbfs_init(void)
{
        int rc = -ENODATA;

        dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
        if (hypfs_diag_init())
                goto fail_dbfs_exit;
        if (hypfs_vm_init())
                goto fail_hypfs_diag_exit;
        hypfs_sprp_init();
        if (hypfs_diag0c_init())
                goto fail_hypfs_sprp_exit;
        rc = hypfs_fs_init();
        if (rc)
                goto fail_hypfs_diag0c_exit;
        return 0;

fail_hypfs_diag0c_exit:
        hypfs_diag0c_exit();
fail_hypfs_sprp_exit:
        hypfs_sprp_exit();
        hypfs_vm_exit();
fail_hypfs_diag_exit:
        hypfs_diag_exit();
        pr_err("Initialization of hypfs failed with rc=%i\n", rc);
fail_dbfs_exit:
        debugfs_remove(dbfs_dir);
        return rc;
}
device_initcall(hypfs_dbfs_init)