// SPDX-License-Identifier: GPL-1.0+
/*
 * zcore module to export memory content and register sets for creating system
 * dumps on SCSI/NVMe disks (zfcp/nvme dump).
 *
 * For more information please refer to Documentation/arch/s390/zfcpdump.rst
 *
 * Copyright IBM Corp. 2003, 2008
 * Author(s): Michael Holzheu
 */

#define pr_fmt(fmt) "zdump: " fmt

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/debugfs.h>
#include <linux/panic_notifier.h>
#include <linux/reboot.h>
#include <linux/uio.h>

#include <asm/asm-offsets.h>
#include <asm/ipl.h>
#include <asm/sclp.h>
#include <asm/setup.h>
#include <linux/uaccess.h>
#include <asm/debug.h>
#include <asm/processor.h>
#include <asm/irqflags.h>
#include <asm/checksum.h>
#include <asm/os_info.h>
#include <asm/maccess.h>
#include "sclp.h"

#define TRACE(x...) debug_sprintf_event(zcore_dbf, 1, x)

enum arch_id {
        ARCH_S390       = 0,
        ARCH_S390X      = 1,
};

struct ipib_info {
        unsigned long   ipib;
        u32             checksum;
}  __attribute__((packed));

static struct debug_info *zcore_dbf;
static int hsa_available;
static struct dentry *zcore_dir;
static struct dentry *zcore_reipl_file;
static struct dentry *zcore_hsa_file;
static struct ipl_parameter_block *zcore_ipl_block;
static unsigned long os_info_flags;

static DEFINE_MUTEX(hsa_buf_mutex);
static char hsa_buf[PAGE_SIZE] __aligned(PAGE_SIZE);

/*
 * Copy memory from HSA to iterator (not reentrant):
 *
 * @iter:  Iterator where memory should be copied to
 * @src:   Start address within HSA where data should be copied
 * @count: Size of buffer, which should be copied
 */
size_t memcpy_hsa_iter(struct iov_iter *iter, unsigned long src, size_t count)
{
        size_t bytes, copied, res = 0;
        unsigned long offset;

        if (!hsa_available)
                return 0;

        mutex_lock(&hsa_buf_mutex);
        while (count) {
                if (sclp_sdias_copy(hsa_buf, src / PAGE_SIZE + 2, 1)) {
                        TRACE("sclp_sdias_copy() failed\n");
                        break;
                }
                offset = src % PAGE_SIZE;
                bytes = min(PAGE_SIZE - offset, count);
                copied = copy_to_iter(hsa_buf + offset, bytes, iter);
                count -= copied;
                src += copied;
                res += copied;
                if (copied < bytes)
                        break;
        }
        mutex_unlock(&hsa_buf_mutex);
        return res;
}

/*
 * Copy memory from HSA to kernel memory (not reentrant):
 *
 * @dest:  Kernel or user buffer where memory should be copied to
 * @src:   Start address within HSA where data should be copied
 * @count: Size of buffer, which should be copied
 */
static inline int memcpy_hsa_kernel(void *dst, unsigned long src, size_t count)
{
        struct iov_iter iter;
        struct kvec kvec;

        kvec.iov_base = dst;
        kvec.iov_len = count;
        iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, count);
        if (memcpy_hsa_iter(&iter, src, count) < count)
                return -EIO;
        return 0;
}

static int __init init_cpu_info(void)
{
        struct save_area *sa;

        /* get info for boot cpu from lowcore, stored in the HSA */
        sa = save_area_boot_cpu();
        if (!sa)
                return -ENOMEM;
        if (memcpy_hsa_kernel(hsa_buf, __LC_FPREGS_SAVE_AREA, 512) < 0) {
                TRACE("could not copy from HSA\n");
                return -EIO;
        }
        save_area_add_regs(sa, hsa_buf); /* vx registers are saved in smp.c */
        return 0;
}

/*
 * Release the HSA
 */
static void release_hsa(void)
{
        diag308(DIAG308_REL_HSA, NULL);
        hsa_available = 0;
}

static ssize_t zcore_reipl_write(struct file *filp, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        if (zcore_ipl_block) {
                diag308(DIAG308_SET, zcore_ipl_block);
                if (os_info_flags & OS_INFO_FLAG_REIPL_CLEAR)
                        diag308(DIAG308_LOAD_CLEAR, NULL);
                /* Use special diag308 subcode for CCW normal ipl */
                if (zcore_ipl_block->pb0_hdr.pbt == IPL_PBT_CCW)
                        diag308(DIAG308_LOAD_NORMAL_DUMP, NULL);
                else
                        diag308(DIAG308_LOAD_NORMAL, NULL);
        }
        return count;
}

static int zcore_reipl_open(struct inode *inode, struct file *filp)
{
        return stream_open(inode, filp);
}

static int zcore_reipl_release(struct inode *inode, struct file *filp)
{
        return 0;
}

static const struct file_operations zcore_reipl_fops = {
        .owner          = THIS_MODULE,
        .write          = zcore_reipl_write,
        .open           = zcore_reipl_open,
        .release        = zcore_reipl_release,
};

static ssize_t zcore_hsa_read(struct file *filp, char __user *buf,
                              size_t count, loff_t *ppos)
{
        static char str[18];

        if (hsa_available)
                snprintf(str, sizeof(str), "%lx\n", sclp.hsa_size);
        else
                snprintf(str, sizeof(str), "0\n");
        return simple_read_from_buffer(buf, count, ppos, str, strlen(str));
}

static ssize_t zcore_hsa_write(struct file *filp, const char __user *buf,
                               size_t count, loff_t *ppos)
{
        char value;

        if (*ppos != 0)
                return -EPIPE;
        if (copy_from_user(&value, buf, 1))
                return -EFAULT;
        if (value != '0')
                return -EINVAL;
        release_hsa();
        return count;
}

static const struct file_operations zcore_hsa_fops = {
        .owner          = THIS_MODULE,
        .write          = zcore_hsa_write,
        .read           = zcore_hsa_read,
        .open           = nonseekable_open,
};

static int __init check_sdias(void)
{
        if (!sclp.hsa_size) {
                TRACE("Could not determine HSA size\n");
                return -ENODEV;
        }
        return 0;
}

/*
 * Provide IPL parameter information block from either HSA or memory
 * for future reipl
 */
static int __init zcore_reipl_init(void)
{
        struct os_info_entry *entry;
        struct ipib_info ipib_info;
        unsigned long os_info_addr;
        struct os_info *os_info;
        int rc;

        rc = memcpy_hsa_kernel(&ipib_info, __LC_DUMP_REIPL, sizeof(ipib_info));
        if (rc)
                return rc;
        if (ipib_info.ipib == 0)
                return 0;
        zcore_ipl_block = (void *) __get_free_page(GFP_KERNEL);
        if (!zcore_ipl_block)
                return -ENOMEM;
        if (ipib_info.ipib < sclp.hsa_size)
                rc = memcpy_hsa_kernel(zcore_ipl_block, ipib_info.ipib,
                                       PAGE_SIZE);
        else
                rc = memcpy_real(zcore_ipl_block, ipib_info.ipib, PAGE_SIZE);
        if (rc || (__force u32)csum_partial(zcore_ipl_block, zcore_ipl_block->hdr.len, 0) !=
            ipib_info.checksum) {
                TRACE("Checksum does not match\n");
                free_page((unsigned long) zcore_ipl_block);
                zcore_ipl_block = NULL;
        }
        /*
         * Read the bit-flags field from os_info flags entry.
         * Return zero even for os_info read or entry checksum errors in order
         * to continue dump processing, considering that os_info could be
         * corrupted on the panicked system.
         */
        os_info = (void *)__get_free_page(GFP_KERNEL);
        if (!os_info)
                return -ENOMEM;
        rc = memcpy_hsa_kernel(&os_info_addr, __LC_OS_INFO, sizeof(os_info_addr));
        if (rc)
                goto out;
        if (os_info_addr < sclp.hsa_size)
                rc = memcpy_hsa_kernel(os_info, os_info_addr, PAGE_SIZE);
        else
                rc = memcpy_real(os_info, os_info_addr, PAGE_SIZE);
        if (rc || os_info_csum(os_info) != os_info->csum)
                goto out;
        entry = &os_info->entry[OS_INFO_FLAGS_ENTRY];
        if (entry->addr && entry->size) {
                if (entry->addr < sclp.hsa_size)
                        rc = memcpy_hsa_kernel(&os_info_flags, entry->addr, sizeof(os_info_flags));
                else
                        rc = memcpy_real(&os_info_flags, entry->addr, sizeof(os_info_flags));
                if (rc || (__force u32)csum_partial(&os_info_flags, entry->size, 0) != entry->csum)
                        os_info_flags = 0;
        }
out:
        free_page((unsigned long)os_info);
        return 0;
}

static int zcore_reboot_and_on_panic_handler(struct notifier_block *self,
                                             unsigned long         event,
                                             void                  *data)
{
        if (hsa_available)
                release_hsa();

        return NOTIFY_OK;
}

static struct notifier_block zcore_reboot_notifier = {
        .notifier_call  = zcore_reboot_and_on_panic_handler,
        /* we need to be notified before reipl and kdump */
        .priority       = INT_MAX,
};

static struct notifier_block zcore_on_panic_notifier = {
        .notifier_call  = zcore_reboot_and_on_panic_handler,
        /* we need to be notified before reipl and kdump */
        .priority       = INT_MAX,
};

static int __init zcore_init(void)
{
        unsigned char arch;
        int rc;

        if (!is_ipl_type_dump())
                return -ENODATA;
        if (oldmem_data.start)
                return -ENODATA;

        zcore_dbf = debug_register("zcore", 4, 1, 4 * sizeof(long));
        debug_register_view(zcore_dbf, &debug_sprintf_view);
        debug_set_level(zcore_dbf, 6);

        if (ipl_info.type == IPL_TYPE_FCP_DUMP) {
                TRACE("type:   fcp\n");
                TRACE("devno:  %x\n", ipl_info.data.fcp.dev_id.devno);
                TRACE("wwpn:   %llx\n", (unsigned long long) ipl_info.data.fcp.wwpn);
                TRACE("lun:    %llx\n", (unsigned long long) ipl_info.data.fcp.lun);
        } else if (ipl_info.type == IPL_TYPE_NVME_DUMP) {
                TRACE("type:   nvme\n");
                TRACE("fid:    %x\n", ipl_info.data.nvme.fid);
                TRACE("nsid:   %x\n", ipl_info.data.nvme.nsid);
        } else if (ipl_info.type == IPL_TYPE_ECKD_DUMP) {
                TRACE("type:   eckd\n");
                TRACE("devno:  %x\n", ipl_info.data.eckd.dev_id.devno);
                TRACE("ssid:   %x\n", ipl_info.data.eckd.dev_id.ssid);
        }

        rc = sclp_sdias_init();
        if (rc)
                goto fail;

        rc = check_sdias();
        if (rc)
                goto fail;
        hsa_available = 1;

        rc = memcpy_hsa_kernel(&arch, __LC_AR_MODE_ID, 1);
        if (rc)
                goto fail;

        if (arch == ARCH_S390) {
                pr_alert("The 64-bit dump tool cannot be used for a "
                         "32-bit system\n");
                rc = -EINVAL;
                goto fail;
        }

        pr_alert("The dump process started for a 64-bit operating system\n");
        rc = init_cpu_info();
        if (rc)
                goto fail;

        rc = zcore_reipl_init();
        if (rc)
                goto fail;

        zcore_dir = debugfs_create_dir("zcore" , NULL);
        zcore_reipl_file = debugfs_create_file("reipl", S_IRUSR, zcore_dir,
                                                NULL, &zcore_reipl_fops);
        zcore_hsa_file = debugfs_create_file("hsa", S_IRUSR|S_IWUSR, zcore_dir,
                                             NULL, &zcore_hsa_fops);

        register_reboot_notifier(&zcore_reboot_notifier);
        atomic_notifier_chain_register(&panic_notifier_list, &zcore_on_panic_notifier);

        return 0;
fail:
        diag308(DIAG308_REL_HSA, NULL);
        return rc;
}
subsys_initcall(zcore_init);