// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PowerNV OPAL Dump Interface
 *
 * Copyright 2013,2014 IBM Corp.
 */

#include <linux/kobject.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/delay.h>
#include <linux/interrupt.h>

#include <asm/opal.h>

#define DUMP_TYPE_FSP   0x01

struct dump_obj {
        struct kobject  kobj;
        struct bin_attribute dump_attr;
        uint32_t        id;  /* becomes object name */
        uint32_t        type;
        uint32_t        size;
        char            *buffer;
};
#define to_dump_obj(x) container_of(x, struct dump_obj, kobj)

struct dump_attribute {
        struct attribute attr;
        ssize_t (*show)(struct dump_obj *dump, struct dump_attribute *attr,
                        char *buf);
        ssize_t (*store)(struct dump_obj *dump, struct dump_attribute *attr,
                         const char *buf, size_t count);
};
#define to_dump_attr(x) container_of(x, struct dump_attribute, attr)

static ssize_t dump_id_show(struct dump_obj *dump_obj,
                            struct dump_attribute *attr,
                            char *buf)
{
        return sprintf(buf, "0x%x\n", dump_obj->id);
}

static const char* dump_type_to_string(uint32_t type)
{
        switch (type) {
        case 0x01: return "SP Dump";
        case 0x02: return "System/Platform Dump";
        case 0x03: return "SMA Dump";
        default: return "unknown";
        }
}

static ssize_t dump_type_show(struct dump_obj *dump_obj,
                              struct dump_attribute *attr,
                              char *buf)
{

        return sprintf(buf, "0x%x %s\n", dump_obj->type,
                       dump_type_to_string(dump_obj->type));
}

static ssize_t dump_ack_show(struct dump_obj *dump_obj,
                             struct dump_attribute *attr,
                             char *buf)
{
        return sprintf(buf, "ack - acknowledge dump\n");
}

/*
 * Send acknowledgement to OPAL
 */
static int64_t dump_send_ack(uint32_t dump_id)
{
        int rc;

        rc = opal_dump_ack(dump_id);
        if (rc)
                pr_warn("%s: Failed to send ack to Dump ID 0x%x (%d)\n",
                        __func__, dump_id, rc);
        return rc;
}

static ssize_t dump_ack_store(struct dump_obj *dump_obj,
                              struct dump_attribute *attr,
                              const char *buf,
                              size_t count)
{
        /*
         * Try to self remove this attribute. If we are successful,
         * delete the kobject itself.
         */
        if (sysfs_remove_file_self(&dump_obj->kobj, &attr->attr)) {
                dump_send_ack(dump_obj->id);
                kobject_put(&dump_obj->kobj);
        }
        return count;
}

/* Attributes of a dump
 * The binary attribute of the dump itself is dynamic
 * due to the dynamic size of the dump
 */
static struct dump_attribute id_attribute =
        __ATTR(id, 0444, dump_id_show, NULL);
static struct dump_attribute type_attribute =
        __ATTR(type, 0444, dump_type_show, NULL);
static struct dump_attribute ack_attribute =
        __ATTR(acknowledge, 0660, dump_ack_show, dump_ack_store);

static ssize_t init_dump_show(struct dump_obj *dump_obj,
                              struct dump_attribute *attr,
                              char *buf)
{
        return sprintf(buf, "1 - initiate Service Processor(FSP) dump\n");
}

static int64_t dump_fips_init(uint8_t type)
{
        int rc;

        rc = opal_dump_init(type);
        if (rc)
                pr_warn("%s: Failed to initiate FSP dump (%d)\n",
                        __func__, rc);
        return rc;
}

static ssize_t init_dump_store(struct dump_obj *dump_obj,
                               struct dump_attribute *attr,
                               const char *buf,
                               size_t count)
{
        int rc;

        rc = dump_fips_init(DUMP_TYPE_FSP);
        if (rc == OPAL_SUCCESS)
                pr_info("%s: Initiated FSP dump\n", __func__);

        return count;
}

static struct dump_attribute initiate_attribute =
        __ATTR(initiate_dump, 0600, init_dump_show, init_dump_store);

static struct attribute *initiate_attrs[] = {
        &initiate_attribute.attr,
        NULL,
};

static struct attribute_group initiate_attr_group = {
        .attrs = initiate_attrs,
};

static struct kset *dump_kset;

static ssize_t dump_attr_show(struct kobject *kobj,
                              struct attribute *attr,
                              char *buf)
{
        struct dump_attribute *attribute;
        struct dump_obj *dump;

        attribute = to_dump_attr(attr);
        dump = to_dump_obj(kobj);

        if (!attribute->show)
                return -EIO;

        return attribute->show(dump, attribute, buf);
}

static ssize_t dump_attr_store(struct kobject *kobj,
                               struct attribute *attr,
                               const char *buf, size_t len)
{
        struct dump_attribute *attribute;
        struct dump_obj *dump;

        attribute = to_dump_attr(attr);
        dump = to_dump_obj(kobj);

        if (!attribute->store)
                return -EIO;

        return attribute->store(dump, attribute, buf, len);
}

static const struct sysfs_ops dump_sysfs_ops = {
        .show = dump_attr_show,
        .store = dump_attr_store,
};

static void dump_release(struct kobject *kobj)
{
        struct dump_obj *dump;

        dump = to_dump_obj(kobj);
        vfree(dump->buffer);
        kfree(dump);
}

static struct attribute *dump_default_attrs[] = {
        &id_attribute.attr,
        &type_attribute.attr,
        &ack_attribute.attr,
        NULL,
};

static struct kobj_type dump_ktype = {
        .sysfs_ops = &dump_sysfs_ops,
        .release = &dump_release,
        .default_attrs = dump_default_attrs,
};

static int64_t dump_read_info(uint32_t *dump_id, uint32_t *dump_size, uint32_t *dump_type)
{
        __be32 id, size, type;
        int rc;

        type = cpu_to_be32(0xffffffff);

        rc = opal_dump_info2(&id, &size, &type);
        if (rc == OPAL_PARAMETER)
                rc = opal_dump_info(&id, &size);

        if (rc) {
                pr_warn("%s: Failed to get dump info (%d)\n",
                        __func__, rc);
                return rc;
        }

        *dump_id = be32_to_cpu(id);
        *dump_size = be32_to_cpu(size);
        *dump_type = be32_to_cpu(type);

        return rc;
}

static int64_t dump_read_data(struct dump_obj *dump)
{
        struct opal_sg_list *list;
        uint64_t addr;
        int64_t rc;

        /* Allocate memory */
        dump->buffer = vzalloc(PAGE_ALIGN(dump->size));
        if (!dump->buffer) {
                pr_err("%s : Failed to allocate memory\n", __func__);
                rc = -ENOMEM;
                goto out;
        }

        /* Generate SG list */
        list = opal_vmalloc_to_sg_list(dump->buffer, dump->size);
        if (!list) {
                rc = -ENOMEM;
                goto out;
        }

        /* First entry address */
        addr = __pa(list);

        /* Fetch data */
        rc = OPAL_BUSY_EVENT;
        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_dump_read(dump->id, addr);
                if (rc == OPAL_BUSY_EVENT) {
                        opal_poll_events(NULL);
                        msleep(20);
                }
        }

        if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL)
                pr_warn("%s: Extract dump failed for ID 0x%x\n",
                        __func__, dump->id);

        /* Free SG list */
        opal_free_sg_list(list);

out:
        return rc;
}

static ssize_t dump_attr_read(struct file *filep, struct kobject *kobj,
                              struct bin_attribute *bin_attr,
                              char *buffer, loff_t pos, size_t count)
{
        ssize_t rc;

        struct dump_obj *dump = to_dump_obj(kobj);

        if (!dump->buffer) {
                rc = dump_read_data(dump);

                if (rc != OPAL_SUCCESS && rc != OPAL_PARTIAL) {
                        vfree(dump->buffer);
                        dump->buffer = NULL;

                        return -EIO;
                }
                if (rc == OPAL_PARTIAL) {
                        /* On a partial read, we just return EIO
                         * and rely on userspace to ask us to try
                         * again.
                         */
                        pr_info("%s: Platform dump partially read. ID = 0x%x\n",
                                __func__, dump->id);
                        return -EIO;
                }
        }

        memcpy(buffer, dump->buffer + pos, count);

        /* You may think we could free the dump buffer now and retrieve
         * it again later if needed, but due to current firmware limitation,
         * that's not the case. So, once read into userspace once,
         * we keep the dump around until it's acknowledged by userspace.
         */

        return count;
}

static void create_dump_obj(uint32_t id, size_t size, uint32_t type)
{
        struct dump_obj *dump;
        int rc;

        dump = kzalloc(sizeof(*dump), GFP_KERNEL);
        if (!dump)
                return;

        dump->kobj.kset = dump_kset;

        kobject_init(&dump->kobj, &dump_ktype);

        sysfs_bin_attr_init(&dump->dump_attr);

        dump->dump_attr.attr.name = "dump";
        dump->dump_attr.attr.mode = 0400;
        dump->dump_attr.size = size;
        dump->dump_attr.read = dump_attr_read;

        dump->id = id;
        dump->size = size;
        dump->type = type;

        rc = kobject_add(&dump->kobj, NULL, "0x%x-0x%x", type, id);
        if (rc) {
                kobject_put(&dump->kobj);
                return;
        }

        /*
         * As soon as the sysfs file for this dump is created/activated there is
         * a chance the opal_errd daemon (or any userspace) might read and
         * acknowledge the dump before kobject_uevent() is called. If that
         * happens then there is a potential race between
         * dump_ack_store->kobject_put() and kobject_uevent() which leads to a
         * use-after-free of a kernfs object resulting in a kernel crash.
         *
         * To avoid that, we need to take a reference on behalf of the bin file,
         * so that our reference remains valid while we call kobject_uevent().
         * We then drop our reference before exiting the function, leaving the
         * bin file to drop the last reference (if it hasn't already).
         */

        /* Take a reference for the bin file */
        kobject_get(&dump->kobj);
        rc = sysfs_create_bin_file(&dump->kobj, &dump->dump_attr);
        if (rc == 0) {
                kobject_uevent(&dump->kobj, KOBJ_ADD);

                pr_info("%s: New platform dump. ID = 0x%x Size %u\n",
                        __func__, dump->id, dump->size);
        } else {
                /* Drop reference count taken for bin file */
                kobject_put(&dump->kobj);
        }

        /* Drop our reference */
        kobject_put(&dump->kobj);
        return;
}

static irqreturn_t process_dump(int irq, void *data)
{
        int rc;
        uint32_t dump_id, dump_size, dump_type;
        char name[22];
        struct kobject *kobj;

        rc = dump_read_info(&dump_id, &dump_size, &dump_type);
        if (rc != OPAL_SUCCESS)
                return IRQ_HANDLED;

        sprintf(name, "0x%x-0x%x", dump_type, dump_id);

        /* we may get notified twice, let's handle
         * that gracefully and not create two conflicting
         * entries.
         */
        kobj = kset_find_obj(dump_kset, name);
        if (kobj) {
                /* Drop reference added by kset_find_obj() */
                kobject_put(kobj);
                return IRQ_HANDLED;
        }

        create_dump_obj(dump_id, dump_size, dump_type);

        return IRQ_HANDLED;
}

void __init opal_platform_dump_init(void)
{
        int rc;
        int dump_irq;

        /* ELOG not supported by firmware */
        if (!opal_check_token(OPAL_DUMP_READ))
                return;

        dump_kset = kset_create_and_add("dump", NULL, opal_kobj);
        if (!dump_kset) {
                pr_warn("%s: Failed to create dump kset\n", __func__);
                return;
        }

        rc = sysfs_create_group(&dump_kset->kobj, &initiate_attr_group);
        if (rc) {
                pr_warn("%s: Failed to create initiate dump attr group\n",
                        __func__);
                kobject_put(&dump_kset->kobj);
                return;
        }

        dump_irq = opal_event_request(ilog2(OPAL_EVENT_DUMP_AVAIL));
        if (!dump_irq) {
                pr_err("%s: Can't register OPAL event irq (%d)\n",
                       __func__, dump_irq);
                return;
        }

        rc = request_threaded_irq(dump_irq, NULL, process_dump,
                                IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
                                "opal-dump", NULL);
        if (rc) {
                pr_err("%s: Can't request OPAL event irq (%d)\n",
                       __func__, rc);
                return;
        }

        if (opal_check_token(OPAL_DUMP_RESEND))
                opal_dump_resend_notification();
}