// SPDX-License-Identifier: GPL-2.0
/*
 *    Hypervisor filesystem for Linux on s390. Diag 204 and 224
 *    implementation.
 *
 *    Copyright IBM Corp. 2006, 2008
 *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
 */

#define KMSG_COMPONENT "hypfs"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <asm/diag.h>
#include <asm/ebcdic.h>
#include "hypfs.h"

#define TMP_SIZE 64             /* size of temporary buffers */

#define DBFS_D204_HDR_VERSION   0

static char *diag224_cpu_names;                 /* diag 224 name table */
static enum diag204_sc diag204_store_sc;        /* used subcode for store */
static enum diag204_format diag204_info_type;   /* used diag 204 data format */

static void *diag204_buf;               /* 4K aligned buffer for diag204 data */
static void *diag204_buf_vmalloc;       /* vmalloc pointer for diag204 data */
static int diag204_buf_pages;           /* number of pages for diag204 data */

static struct dentry *dbfs_d204_file;

/*
 * DIAG 204 member access functions.
 *
 * Since we have two different diag 204 data formats for old and new s390
 * machines, we do not access the structs directly, but use getter functions for
 * each struct member instead. This should make the code more readable.
 */

/* Time information block */

static inline int info_blk_hdr__size(enum diag204_format type)
{
        if (type == DIAG204_INFO_SIMPLE)
                return sizeof(struct diag204_info_blk_hdr);
        else /* DIAG204_INFO_EXT */
                return sizeof(struct diag204_x_info_blk_hdr);
}

static inline __u8 info_blk_hdr__npar(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_info_blk_hdr *)hdr)->npar;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_info_blk_hdr *)hdr)->npar;
}

static inline __u8 info_blk_hdr__flags(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_info_blk_hdr *)hdr)->flags;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_info_blk_hdr *)hdr)->flags;
}

static inline __u16 info_blk_hdr__pcpus(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_info_blk_hdr *)hdr)->phys_cpus;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_info_blk_hdr *)hdr)->phys_cpus;
}

/* Partition header */

static inline int part_hdr__size(enum diag204_format type)
{
        if (type == DIAG204_INFO_SIMPLE)
                return sizeof(struct diag204_part_hdr);
        else /* DIAG204_INFO_EXT */
                return sizeof(struct diag204_x_part_hdr);
}

static inline __u8 part_hdr__rcpus(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_part_hdr *)hdr)->cpus;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_part_hdr *)hdr)->rcpus;
}

static inline void part_hdr__part_name(enum diag204_format type, void *hdr,
                                       char *name)
{
        if (type == DIAG204_INFO_SIMPLE)
                memcpy(name, ((struct diag204_part_hdr *)hdr)->part_name,
                       DIAG204_LPAR_NAME_LEN);
        else /* DIAG204_INFO_EXT */
                memcpy(name, ((struct diag204_x_part_hdr *)hdr)->part_name,
                       DIAG204_LPAR_NAME_LEN);
        EBCASC(name, DIAG204_LPAR_NAME_LEN);
        name[DIAG204_LPAR_NAME_LEN] = 0;
        strim(name);
}

/* CPU info block */

static inline int cpu_info__size(enum diag204_format type)
{
        if (type == DIAG204_INFO_SIMPLE)
                return sizeof(struct diag204_cpu_info);
        else /* DIAG204_INFO_EXT */
                return sizeof(struct diag204_x_cpu_info);
}

static inline __u8 cpu_info__ctidx(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_cpu_info *)hdr)->ctidx;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_cpu_info *)hdr)->ctidx;
}

static inline __u16 cpu_info__cpu_addr(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_cpu_info *)hdr)->cpu_addr;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_cpu_info *)hdr)->cpu_addr;
}

static inline __u64 cpu_info__acc_time(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_cpu_info *)hdr)->acc_time;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_cpu_info *)hdr)->acc_time;
}

static inline __u64 cpu_info__lp_time(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_cpu_info *)hdr)->lp_time;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_cpu_info *)hdr)->lp_time;
}

static inline __u64 cpu_info__online_time(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return 0;       /* online_time not available in simple info */
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_cpu_info *)hdr)->online_time;
}

/* Physical header */

static inline int phys_hdr__size(enum diag204_format type)
{
        if (type == DIAG204_INFO_SIMPLE)
                return sizeof(struct diag204_phys_hdr);
        else /* DIAG204_INFO_EXT */
                return sizeof(struct diag204_x_phys_hdr);
}

static inline __u8 phys_hdr__cpus(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_phys_hdr *)hdr)->cpus;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_phys_hdr *)hdr)->cpus;
}

/* Physical CPU info block */

static inline int phys_cpu__size(enum diag204_format type)
{
        if (type == DIAG204_INFO_SIMPLE)
                return sizeof(struct diag204_phys_cpu);
        else /* DIAG204_INFO_EXT */
                return sizeof(struct diag204_x_phys_cpu);
}

static inline __u16 phys_cpu__cpu_addr(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_phys_cpu *)hdr)->cpu_addr;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_phys_cpu *)hdr)->cpu_addr;
}

static inline __u64 phys_cpu__mgm_time(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_phys_cpu *)hdr)->mgm_time;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_phys_cpu *)hdr)->mgm_time;
}

static inline __u64 phys_cpu__ctidx(enum diag204_format type, void *hdr)
{
        if (type == DIAG204_INFO_SIMPLE)
                return ((struct diag204_phys_cpu *)hdr)->ctidx;
        else /* DIAG204_INFO_EXT */
                return ((struct diag204_x_phys_cpu *)hdr)->ctidx;
}

/* Diagnose 204 functions */
/*
 * For the old diag subcode 4 with simple data format we have to use real
 * memory. If we use subcode 6 or 7 with extended data format, we can (and
 * should) use vmalloc, since we need a lot of memory in that case. Currently
 * up to 93 pages!
 */

static void diag204_free_buffer(void)
{
        if (!diag204_buf)
                return;
        if (diag204_buf_vmalloc) {
                vfree(diag204_buf_vmalloc);
                diag204_buf_vmalloc = NULL;
        } else {
                free_pages((unsigned long) diag204_buf, 0);
        }
        diag204_buf = NULL;
}

static void *page_align_ptr(void *ptr)
{
        return (void *) PAGE_ALIGN((unsigned long) ptr);
}

static void *diag204_alloc_vbuf(int pages)
{
        /* The buffer has to be page aligned! */
        diag204_buf_vmalloc = vmalloc(array_size(PAGE_SIZE, (pages + 1)));
        if (!diag204_buf_vmalloc)
                return ERR_PTR(-ENOMEM);
        diag204_buf = page_align_ptr(diag204_buf_vmalloc);
        diag204_buf_pages = pages;
        return diag204_buf;
}

static void *diag204_alloc_rbuf(void)
{
        diag204_buf = (void*)__get_free_pages(GFP_KERNEL,0);
        if (!diag204_buf)
                return ERR_PTR(-ENOMEM);
        diag204_buf_pages = 1;
        return diag204_buf;
}

static void *diag204_get_buffer(enum diag204_format fmt, int *pages)
{
        if (diag204_buf) {
                *pages = diag204_buf_pages;
                return diag204_buf;
        }
        if (fmt == DIAG204_INFO_SIMPLE) {
                *pages = 1;
                return diag204_alloc_rbuf();
        } else {/* DIAG204_INFO_EXT */
                *pages = diag204((unsigned long)DIAG204_SUBC_RSI |
                                 (unsigned long)DIAG204_INFO_EXT, 0, NULL);
                if (*pages <= 0)
                        return ERR_PTR(-ENOSYS);
                else
                        return diag204_alloc_vbuf(*pages);
        }
}

/*
 * diag204_probe() has to find out, which type of diagnose 204 implementation
 * we have on our machine. Currently there are three possible scanarios:
 *   - subcode 4   + simple data format (only one page)
 *   - subcode 4-6 + extended data format
 *   - subcode 4-7 + extended data format
 *
 * Subcode 5 is used to retrieve the size of the data, provided by subcodes
 * 6 and 7. Subcode 7 basically has the same function as subcode 6. In addition
 * to subcode 6 it provides also information about secondary cpus.
 * In order to get as much information as possible, we first try
 * subcode 7, then 6 and if both fail, we use subcode 4.
 */

static int diag204_probe(void)
{
        void *buf;
        int pages, rc;

        buf = diag204_get_buffer(DIAG204_INFO_EXT, &pages);
        if (!IS_ERR(buf)) {
                if (diag204((unsigned long)DIAG204_SUBC_STIB7 |
                            (unsigned long)DIAG204_INFO_EXT, pages, buf) >= 0) {
                        diag204_store_sc = DIAG204_SUBC_STIB7;
                        diag204_info_type = DIAG204_INFO_EXT;
                        goto out;
                }
                if (diag204((unsigned long)DIAG204_SUBC_STIB6 |
                            (unsigned long)DIAG204_INFO_EXT, pages, buf) >= 0) {
                        diag204_store_sc = DIAG204_SUBC_STIB6;
                        diag204_info_type = DIAG204_INFO_EXT;
                        goto out;
                }
                diag204_free_buffer();
        }

        /* subcodes 6 and 7 failed, now try subcode 4 */

        buf = diag204_get_buffer(DIAG204_INFO_SIMPLE, &pages);
        if (IS_ERR(buf)) {
                rc = PTR_ERR(buf);
                goto fail_alloc;
        }
        if (diag204((unsigned long)DIAG204_SUBC_STIB4 |
                    (unsigned long)DIAG204_INFO_SIMPLE, pages, buf) >= 0) {
                diag204_store_sc = DIAG204_SUBC_STIB4;
                diag204_info_type = DIAG204_INFO_SIMPLE;
                goto out;
        } else {
                rc = -ENOSYS;
                goto fail_store;
        }
out:
        rc = 0;
fail_store:
        diag204_free_buffer();
fail_alloc:
        return rc;
}

static int diag204_do_store(void *buf, int pages)
{
        int rc;

        rc = diag204((unsigned long) diag204_store_sc |
                     (unsigned long) diag204_info_type, pages, buf);
        return rc < 0 ? -ENOSYS : 0;
}

static void *diag204_store(void)
{
        void *buf;
        int pages, rc;

        buf = diag204_get_buffer(diag204_info_type, &pages);
        if (IS_ERR(buf))
                goto out;
        rc = diag204_do_store(buf, pages);
        if (rc)
                return ERR_PTR(rc);
out:
        return buf;
}

/* Diagnose 224 functions */

static int diag224_get_name_table(void)
{
        /* memory must be below 2GB */
        diag224_cpu_names = (char *) __get_free_page(GFP_KERNEL | GFP_DMA);
        if (!diag224_cpu_names)
                return -ENOMEM;
        if (diag224(diag224_cpu_names)) {
                free_page((unsigned long) diag224_cpu_names);
                return -EOPNOTSUPP;
        }
        EBCASC(diag224_cpu_names + 16, (*diag224_cpu_names + 1) * 16);
        return 0;
}

static void diag224_delete_name_table(void)
{
        free_page((unsigned long) diag224_cpu_names);
}

static int diag224_idx2name(int index, char *name)
{
        memcpy(name, diag224_cpu_names + ((index + 1) * DIAG204_CPU_NAME_LEN),
               DIAG204_CPU_NAME_LEN);
        name[DIAG204_CPU_NAME_LEN] = 0;
        strim(name);
        return 0;
}

struct dbfs_d204_hdr {
        u64     len;            /* Length of d204 buffer without header */
        u16     version;        /* Version of header */
        u8      sc;             /* Used subcode */
        char    reserved[53];
} __attribute__ ((packed));

struct dbfs_d204 {
        struct dbfs_d204_hdr    hdr;    /* 64 byte header */
        char                    buf[];  /* d204 buffer */
} __attribute__ ((packed));

static int dbfs_d204_create(void **data, void **data_free_ptr, size_t *size)
{
        struct dbfs_d204 *d204;
        int rc, buf_size;
        void *base;

        buf_size = PAGE_SIZE * (diag204_buf_pages + 1) + sizeof(d204->hdr);
        base = vzalloc(buf_size);
        if (!base)
                return -ENOMEM;
        d204 = page_align_ptr(base + sizeof(d204->hdr)) - sizeof(d204->hdr);
        rc = diag204_do_store(d204->buf, diag204_buf_pages);
        if (rc) {
                vfree(base);
                return rc;
        }
        d204->hdr.version = DBFS_D204_HDR_VERSION;
        d204->hdr.len = PAGE_SIZE * diag204_buf_pages;
        d204->hdr.sc = diag204_store_sc;
        *data = d204;
        *data_free_ptr = base;
        *size = d204->hdr.len + sizeof(struct dbfs_d204_hdr);
        return 0;
}

static struct hypfs_dbfs_file dbfs_file_d204 = {
        .name           = "diag_204",
        .data_create    = dbfs_d204_create,
        .data_free      = vfree,
};

__init int hypfs_diag_init(void)
{
        int rc;

        if (diag204_probe()) {
                pr_err("The hardware system does not support hypfs\n");
                return -ENODATA;
        }

        if (diag204_info_type == DIAG204_INFO_EXT)
                hypfs_dbfs_create_file(&dbfs_file_d204);

        if (MACHINE_IS_LPAR) {
                rc = diag224_get_name_table();
                if (rc) {
                        pr_err("The hardware system does not provide all "
                               "functions required by hypfs\n");
                        debugfs_remove(dbfs_d204_file);
                        return rc;
                }
        }
        return 0;
}

void hypfs_diag_exit(void)
{
        debugfs_remove(dbfs_d204_file);
        diag224_delete_name_table();
        diag204_free_buffer();
        hypfs_dbfs_remove_file(&dbfs_file_d204);
}

/*
 * Functions to create the directory structure
 * *******************************************
 */

static int hypfs_create_cpu_files(struct dentry *cpus_dir, void *cpu_info)
{
        struct dentry *cpu_dir;
        char buffer[TMP_SIZE];
        void *rc;

        snprintf(buffer, TMP_SIZE, "%d", cpu_info__cpu_addr(diag204_info_type,
                                                            cpu_info));
        cpu_dir = hypfs_mkdir(cpus_dir, buffer);
        rc = hypfs_create_u64(cpu_dir, "mgmtime",
                              cpu_info__acc_time(diag204_info_type, cpu_info) -
                              cpu_info__lp_time(diag204_info_type, cpu_info));
        if (IS_ERR(rc))
                return PTR_ERR(rc);
        rc = hypfs_create_u64(cpu_dir, "cputime",
                              cpu_info__lp_time(diag204_info_type, cpu_info));
        if (IS_ERR(rc))
                return PTR_ERR(rc);
        if (diag204_info_type == DIAG204_INFO_EXT) {
                rc = hypfs_create_u64(cpu_dir, "onlinetime",
                                      cpu_info__online_time(diag204_info_type,
                                                            cpu_info));
                if (IS_ERR(rc))
                        return PTR_ERR(rc);
        }
        diag224_idx2name(cpu_info__ctidx(diag204_info_type, cpu_info), buffer);
        rc = hypfs_create_str(cpu_dir, "type", buffer);
        return PTR_ERR_OR_ZERO(rc);
}

static void *hypfs_create_lpar_files(struct dentry *systems_dir, void *part_hdr)
{
        struct dentry *cpus_dir;
        struct dentry *lpar_dir;
        char lpar_name[DIAG204_LPAR_NAME_LEN + 1];
        void *cpu_info;
        int i;

        part_hdr__part_name(diag204_info_type, part_hdr, lpar_name);
        lpar_name[DIAG204_LPAR_NAME_LEN] = 0;
        lpar_dir = hypfs_mkdir(systems_dir, lpar_name);
        if (IS_ERR(lpar_dir))
                return lpar_dir;
        cpus_dir = hypfs_mkdir(lpar_dir, "cpus");
        if (IS_ERR(cpus_dir))
                return cpus_dir;
        cpu_info = part_hdr + part_hdr__size(diag204_info_type);
        for (i = 0; i < part_hdr__rcpus(diag204_info_type, part_hdr); i++) {
                int rc;
                rc = hypfs_create_cpu_files(cpus_dir, cpu_info);
                if (rc)
                        return ERR_PTR(rc);
                cpu_info += cpu_info__size(diag204_info_type);
        }
        return cpu_info;
}

static int hypfs_create_phys_cpu_files(struct dentry *cpus_dir, void *cpu_info)
{
        struct dentry *cpu_dir;
        char buffer[TMP_SIZE];
        void *rc;

        snprintf(buffer, TMP_SIZE, "%i", phys_cpu__cpu_addr(diag204_info_type,
                                                            cpu_info));
        cpu_dir = hypfs_mkdir(cpus_dir, buffer);
        if (IS_ERR(cpu_dir))
                return PTR_ERR(cpu_dir);
        rc = hypfs_create_u64(cpu_dir, "mgmtime",
                              phys_cpu__mgm_time(diag204_info_type, cpu_info));
        if (IS_ERR(rc))
                return PTR_ERR(rc);
        diag224_idx2name(phys_cpu__ctidx(diag204_info_type, cpu_info), buffer);
        rc = hypfs_create_str(cpu_dir, "type", buffer);
        return PTR_ERR_OR_ZERO(rc);
}

static void *hypfs_create_phys_files(struct dentry *parent_dir, void *phys_hdr)
{
        int i;
        void *cpu_info;
        struct dentry *cpus_dir;

        cpus_dir = hypfs_mkdir(parent_dir, "cpus");
        if (IS_ERR(cpus_dir))
                return cpus_dir;
        cpu_info = phys_hdr + phys_hdr__size(diag204_info_type);
        for (i = 0; i < phys_hdr__cpus(diag204_info_type, phys_hdr); i++) {
                int rc;
                rc = hypfs_create_phys_cpu_files(cpus_dir, cpu_info);
                if (rc)
                        return ERR_PTR(rc);
                cpu_info += phys_cpu__size(diag204_info_type);
        }
        return cpu_info;
}

int hypfs_diag_create_files(struct dentry *root)
{
        struct dentry *systems_dir, *hyp_dir;
        void *time_hdr, *part_hdr;
        int i, rc;
        void *buffer, *ptr;

        buffer = diag204_store();
        if (IS_ERR(buffer))
                return PTR_ERR(buffer);

        systems_dir = hypfs_mkdir(root, "systems");
        if (IS_ERR(systems_dir)) {
                rc = PTR_ERR(systems_dir);
                goto err_out;
        }
        time_hdr = (struct x_info_blk_hdr *)buffer;
        part_hdr = time_hdr + info_blk_hdr__size(diag204_info_type);
        for (i = 0; i < info_blk_hdr__npar(diag204_info_type, time_hdr); i++) {
                part_hdr = hypfs_create_lpar_files(systems_dir, part_hdr);
                if (IS_ERR(part_hdr)) {
                        rc = PTR_ERR(part_hdr);
                        goto err_out;
                }
        }
        if (info_blk_hdr__flags(diag204_info_type, time_hdr) &
            DIAG204_LPAR_PHYS_FLG) {
                ptr = hypfs_create_phys_files(root, part_hdr);
                if (IS_ERR(ptr)) {
                        rc = PTR_ERR(ptr);
                        goto err_out;
                }
        }
        hyp_dir = hypfs_mkdir(root, "hyp");
        if (IS_ERR(hyp_dir)) {
                rc = PTR_ERR(hyp_dir);
                goto err_out;
        }
        ptr = hypfs_create_str(hyp_dir, "type", "LPAR Hypervisor");
        if (IS_ERR(ptr)) {
                rc = PTR_ERR(ptr);
                goto err_out;
        }
        rc = 0;

err_out:
        return rc;
}