/*
 * zcore module to export memory content and register sets for creating system
 * dumps on SCSI disks (zfcpdump). The "zcore/mem" debugfs file shows the same
 * dump format as s390 standalone dumps.
 *
 * For more information please refer to Documentation/s390/zfcpdump.txt
 *
 * Copyright IBM Corp. 2003, 2008
 * Author(s): Michael Holzheu
 */

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

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/miscdevice.h>
#include <linux/debugfs.h>
#include <linux/module.h>
#include <asm/asm-offsets.h>
#include <asm/ipl.h>
#include <asm/sclp.h>
#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/debug.h>
#include <asm/processor.h>
#include <asm/irqflags.h>
#include <asm/checksum.h>
#include "sclp.h"

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

#define TO_USER         1
#define TO_KERNEL       0
#define CHUNK_INFO_SIZE 34 /* 2 16-byte char, each followed by blank */

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

/* dump system info */

struct sys_info {
        enum arch_id     arch;
        unsigned long    sa_base;
        u32              sa_size;
        int              cpu_map[NR_CPUS];
        unsigned long    mem_size;
        struct save_area lc_mask;
};

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

static struct sys_info sys_info;
static struct debug_info *zcore_dbf;
static int hsa_available;
static struct dentry *zcore_dir;
static struct dentry *zcore_file;
static struct dentry *zcore_memmap_file;
static struct dentry *zcore_reipl_file;
static struct dentry *zcore_hsa_file;
static struct ipl_parameter_block *ipl_block;

/*
 * Copy memory from HSA to kernel or user 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
 * @mode:  Either TO_KERNEL or TO_USER
 */
int memcpy_hsa(void *dest, unsigned long src, size_t count, int mode)
{
        int offs, blk_num;
        static char buf[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));

        if (!hsa_available)
                return -ENODATA;
        if (count == 0)
                return 0;

        /* copy first block */
        offs = 0;
        if ((src % PAGE_SIZE) != 0) {
                blk_num = src / PAGE_SIZE + 2;
                if (sclp_sdias_copy(buf, blk_num, 1)) {
                        TRACE("sclp_sdias_copy() failed\n");
                        return -EIO;
                }
                offs = min((PAGE_SIZE - (src % PAGE_SIZE)), count);
                if (mode == TO_USER) {
                        if (copy_to_user((__force __user void*) dest,
                                         buf + (src % PAGE_SIZE), offs))
                                return -EFAULT;
                } else
                        memcpy(dest, buf + (src % PAGE_SIZE), offs);
        }
        if (offs == count)
                goto out;

        /* copy middle */
        for (; (offs + PAGE_SIZE) <= count; offs += PAGE_SIZE) {
                blk_num = (src + offs) / PAGE_SIZE + 2;
                if (sclp_sdias_copy(buf, blk_num, 1)) {
                        TRACE("sclp_sdias_copy() failed\n");
                        return -EIO;
                }
                if (mode == TO_USER) {
                        if (copy_to_user((__force __user void*) dest + offs,
                                         buf, PAGE_SIZE))
                                return -EFAULT;
                } else
                        memcpy(dest + offs, buf, PAGE_SIZE);
        }
        if (offs == count)
                goto out;

        /* copy last block */
        blk_num = (src + offs) / PAGE_SIZE + 2;
        if (sclp_sdias_copy(buf, blk_num, 1)) {
                TRACE("sclp_sdias_copy() failed\n");
                return -EIO;
        }
        if (mode == TO_USER) {
                if (copy_to_user((__force __user void*) dest + offs, buf,
                                 count - offs))
                        return -EFAULT;
        } else
                memcpy(dest + offs, buf, count - offs);
out:
        return 0;
}

static int memcpy_hsa_user(void __user *dest, unsigned long src, size_t count)
{
        return memcpy_hsa((void __force *) dest, src, count, TO_USER);
}

static int memcpy_hsa_kernel(void *dest, unsigned long src, size_t count)
{
        return memcpy_hsa(dest, src, count, TO_KERNEL);
}

static int __init init_cpu_info(enum arch_id arch)
{
        struct save_area *sa;

        /* get info for boot cpu from lowcore, stored in the HSA */

        sa = dump_save_area_create(0);
        if (!sa)
                return -ENOMEM;
        if (memcpy_hsa_kernel(sa, sys_info.sa_base, sys_info.sa_size) < 0) {
                TRACE("could not copy from HSA\n");
                kfree(sa);
                return -EIO;
        }
        return 0;
}

static DEFINE_MUTEX(zcore_mutex);

#define DUMP_VERSION    0x5
#define DUMP_MAGIC      0xa8190173618f23fdULL
#define DUMP_ARCH_S390X 2
#define DUMP_ARCH_S390  1
#define HEADER_SIZE     4096

/* dump header dumped according to s390 crash dump format */

struct zcore_header {
        u64 magic;
        u32 version;
        u32 header_size;
        u32 dump_level;
        u32 page_size;
        u64 mem_size;
        u64 mem_start;
        u64 mem_end;
        u32 num_pages;
        u32 pad1;
        u64 tod;
        struct cpuid cpu_id;
        u32 arch_id;
        u32 volnr;
        u32 build_arch;
        u64 rmem_size;
        u8 mvdump;
        u16 cpu_cnt;
        u16 real_cpu_cnt;
        u8 end_pad1[0x200-0x061];
        u64 mvdump_sign;
        u64 mvdump_zipl_time;
        u8 end_pad2[0x800-0x210];
        u32 lc_vec[512];
} __attribute__((packed,__aligned__(16)));

static struct zcore_header zcore_header = {
        .magic          = DUMP_MAGIC,
        .version        = DUMP_VERSION,
        .header_size    = 4096,
        .dump_level     = 0,
        .page_size      = PAGE_SIZE,
        .mem_start      = 0,
#ifdef CONFIG_64BIT
        .build_arch     = DUMP_ARCH_S390X,
#else
        .build_arch     = DUMP_ARCH_S390,
#endif
};

/*
 * Copy lowcore info to buffer. Use map in order to copy only register parts.
 *
 * @buf:    User buffer
 * @sa:     Pointer to save area
 * @sa_off: Offset in save area to copy
 * @len:    Number of bytes to copy
 */
static int copy_lc(void __user *buf, void *sa, int sa_off, int len)
{
        int i;
        char *lc_mask = (char*)&sys_info.lc_mask;

        for (i = 0; i < len; i++) {
                if (!lc_mask[i + sa_off])
                        continue;
                if (copy_to_user(buf + i, sa + sa_off + i, 1))
                        return -EFAULT;
        }
        return 0;
}

/*
 * Copy lowcores info to memory, if necessary
 *
 * @buf:   User buffer
 * @addr:  Start address of buffer in dump memory
 * @count: Size of buffer
 */
static int zcore_add_lc(char __user *buf, unsigned long start, size_t count)
{
        unsigned long end;
        int i;

        if (count == 0)
                return 0;

        end = start + count;
        for (i = 0; i < dump_save_areas.count; i++) {
                unsigned long cp_start, cp_end; /* copy range */
                unsigned long sa_start, sa_end; /* save area range */
                unsigned long prefix;
                unsigned long sa_off, len, buf_off;
                struct save_area *save_area = dump_save_areas.areas[i];

                prefix = save_area->pref_reg;
                sa_start = prefix + sys_info.sa_base;
                sa_end = prefix + sys_info.sa_base + sys_info.sa_size;

                if ((end < sa_start) || (start > sa_end))
                        continue;
                cp_start = max(start, sa_start);
                cp_end = min(end, sa_end);

                buf_off = cp_start - start;
                sa_off = cp_start - sa_start;
                len = cp_end - cp_start;

                TRACE("copy_lc for: %lx\n", start);
                if (copy_lc(buf + buf_off, save_area, sa_off, len))
                        return -EFAULT;
        }
        return 0;
}

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

/*
 * Read routine for zcore character device
 * First 4K are dump header
 * Next 32MB are HSA Memory
 * Rest is read from absolute Memory
 */
static ssize_t zcore_read(struct file *file, char __user *buf, size_t count,
                          loff_t *ppos)
{
        unsigned long mem_start; /* Start address in memory */
        size_t mem_offs;         /* Offset in dump memory */
        size_t hdr_count;        /* Size of header part of output buffer */
        size_t size;
        int rc;

        mutex_lock(&zcore_mutex);

        if (*ppos > (sys_info.mem_size + HEADER_SIZE)) {
                rc = -EINVAL;
                goto fail;
        }

        count = min(count, (size_t) (sys_info.mem_size + HEADER_SIZE - *ppos));

        /* Copy dump header */
        if (*ppos < HEADER_SIZE) {
                size = min(count, (size_t) (HEADER_SIZE - *ppos));
                if (copy_to_user(buf, &zcore_header + *ppos, size)) {
                        rc = -EFAULT;
                        goto fail;
                }
                hdr_count = size;
                mem_start = 0;
        } else {
                hdr_count = 0;
                mem_start = *ppos - HEADER_SIZE;
        }

        mem_offs = 0;

        /* Copy from HSA data */
        if (*ppos < sclp_get_hsa_size() + HEADER_SIZE) {
                size = min((count - hdr_count),
                           (size_t) (sclp_get_hsa_size() - mem_start));
                rc = memcpy_hsa_user(buf + hdr_count, mem_start, size);
                if (rc)
                        goto fail;

                mem_offs += size;
        }

        /* Copy from real mem */
        size = count - mem_offs - hdr_count;
        rc = copy_to_user_real(buf + hdr_count + mem_offs,
                               (void *) mem_start + mem_offs, size);
        if (rc)
                goto fail;

        /*
         * Since s390 dump analysis tools like lcrash or crash
         * expect register sets in the prefix pages of the cpus,
         * we copy them into the read buffer, if necessary.
         * buf + hdr_count: Start of memory part of output buffer
         * mem_start: Start memory address to copy from
         * count - hdr_count: Size of memory area to copy
         */
        if (zcore_add_lc(buf + hdr_count, mem_start, count - hdr_count)) {
                rc = -EFAULT;
                goto fail;
        }
        *ppos += count;
fail:
        mutex_unlock(&zcore_mutex);
        return (rc < 0) ? rc : count;
}

static int zcore_open(struct inode *inode, struct file *filp)
{
        if (!hsa_available)
                return -ENODATA;
        else
                return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}

static int zcore_release(struct inode *inode, struct file *filep)
{
        if (hsa_available)
                release_hsa();
        return 0;
}

static loff_t zcore_lseek(struct file *file, loff_t offset, int orig)
{
        loff_t rc;

        mutex_lock(&zcore_mutex);
        switch (orig) {
        case 0:
                file->f_pos = offset;
                rc = file->f_pos;
                break;
        case 1:
                file->f_pos += offset;
                rc = file->f_pos;
                break;
        default:
                rc = -EINVAL;
        }
        mutex_unlock(&zcore_mutex);
        return rc;
}

static const struct file_operations zcore_fops = {
        .owner          = THIS_MODULE,
        .llseek         = zcore_lseek,
        .read           = zcore_read,
        .open           = zcore_open,
        .release        = zcore_release,
};

static ssize_t zcore_memmap_read(struct file *filp, char __user *buf,
                                 size_t count, loff_t *ppos)
{
        return simple_read_from_buffer(buf, count, ppos, filp->private_data,
                                       MEMORY_CHUNKS * CHUNK_INFO_SIZE);
}

static int zcore_memmap_open(struct inode *inode, struct file *filp)
{
        int i;
        char *buf;
        struct mem_chunk *chunk_array;

        chunk_array = kzalloc(MEMORY_CHUNKS * sizeof(struct mem_chunk),
                              GFP_KERNEL);
        if (!chunk_array)
                return -ENOMEM;
        detect_memory_layout(chunk_array, 0);
        buf = kzalloc(MEMORY_CHUNKS * CHUNK_INFO_SIZE, GFP_KERNEL);
        if (!buf) {
                kfree(chunk_array);
                return -ENOMEM;
        }
        for (i = 0; i < MEMORY_CHUNKS; i++) {
                sprintf(buf + (i * CHUNK_INFO_SIZE), "%016llx %016llx ",
                        (unsigned long long) chunk_array[i].addr,
                        (unsigned long long) chunk_array[i].size);
                if (chunk_array[i].size == 0)
                        break;
        }
        kfree(chunk_array);
        filp->private_data = buf;
        return nonseekable_open(inode, filp);
}

static int zcore_memmap_release(struct inode *inode, struct file *filp)
{
        kfree(filp->private_data);
        return 0;
}

static const struct file_operations zcore_memmap_fops = {
        .owner          = THIS_MODULE,
        .read           = zcore_memmap_read,
        .open           = zcore_memmap_open,
        .release        = zcore_memmap_release,
        .llseek         = no_llseek,
};

static ssize_t zcore_reipl_write(struct file *filp, const char __user *buf,
                                 size_t count, loff_t *ppos)
{
        if (ipl_block) {
                diag308(DIAG308_SET, ipl_block);
                diag308(DIAG308_IPL, NULL);
        }
        return count;
}

static int zcore_reipl_open(struct inode *inode, struct file *filp)
{
        return nonseekable_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,
        .llseek         = no_llseek,
};

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_get_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,
        .llseek         = no_llseek,
};

#ifdef CONFIG_32BIT

static void __init set_lc_mask(struct save_area *map)
{
        memset(&map->ext_save, 0xff, sizeof(map->ext_save));
        memset(&map->timer, 0xff, sizeof(map->timer));
        memset(&map->clk_cmp, 0xff, sizeof(map->clk_cmp));
        memset(&map->psw, 0xff, sizeof(map->psw));
        memset(&map->pref_reg, 0xff, sizeof(map->pref_reg));
        memset(&map->acc_regs, 0xff, sizeof(map->acc_regs));
        memset(&map->fp_regs, 0xff, sizeof(map->fp_regs));
        memset(&map->gp_regs, 0xff, sizeof(map->gp_regs));
        memset(&map->ctrl_regs, 0xff, sizeof(map->ctrl_regs));
}

#else /* CONFIG_32BIT */

static void __init set_lc_mask(struct save_area *map)
{
        memset(&map->fp_regs, 0xff, sizeof(map->fp_regs));
        memset(&map->gp_regs, 0xff, sizeof(map->gp_regs));
        memset(&map->psw, 0xff, sizeof(map->psw));
        memset(&map->pref_reg, 0xff, sizeof(map->pref_reg));
        memset(&map->fp_ctrl_reg, 0xff, sizeof(map->fp_ctrl_reg));
        memset(&map->tod_reg, 0xff, sizeof(map->tod_reg));
        memset(&map->timer, 0xff, sizeof(map->timer));
        memset(&map->clk_cmp, 0xff, sizeof(map->clk_cmp));
        memset(&map->acc_regs, 0xff, sizeof(map->acc_regs));
        memset(&map->ctrl_regs, 0xff, sizeof(map->ctrl_regs));
}

#endif /* CONFIG_32BIT */

/*
 * Initialize dump globals for a given architecture
 */
static int __init sys_info_init(enum arch_id arch, unsigned long mem_end)
{
        int rc;

        switch (arch) {
        case ARCH_S390X:
                pr_alert("DETECTED 'S390X (64 bit) OS'\n");
                break;
        case ARCH_S390:
                pr_alert("DETECTED 'S390 (32 bit) OS'\n");
                break;
        default:
                pr_alert("0x%x is an unknown architecture.\n",arch);
                return -EINVAL;
        }
        sys_info.sa_base = SAVE_AREA_BASE;
        sys_info.sa_size = sizeof(struct save_area);
        sys_info.arch = arch;
        set_lc_mask(&sys_info.lc_mask);
        rc = init_cpu_info(arch);
        if (rc)
                return rc;
        sys_info.mem_size = mem_end;

        return 0;
}

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

static int __init get_mem_info(unsigned long *mem, unsigned long *end)
{
        int i;
        struct mem_chunk *chunk_array;

        chunk_array = kzalloc(MEMORY_CHUNKS * sizeof(struct mem_chunk),
                              GFP_KERNEL);
        if (!chunk_array)
                return -ENOMEM;
        detect_memory_layout(chunk_array, 0);
        for (i = 0; i < MEMORY_CHUNKS; i++) {
                if (chunk_array[i].size == 0)
                        break;
                *mem += chunk_array[i].size;
                *end = max(*end, chunk_array[i].addr + chunk_array[i].size);
        }
        kfree(chunk_array);
        return 0;
}

static void __init zcore_header_init(int arch, struct zcore_header *hdr,
                                     unsigned long mem_size)
{
        u32 prefix;
        int i;

        if (arch == ARCH_S390X)
                hdr->arch_id = DUMP_ARCH_S390X;
        else
                hdr->arch_id = DUMP_ARCH_S390;
        hdr->mem_size = mem_size;
        hdr->rmem_size = mem_size;
        hdr->mem_end = sys_info.mem_size;
        hdr->num_pages = mem_size / PAGE_SIZE;
        hdr->tod = get_tod_clock();
        get_cpu_id(&hdr->cpu_id);
        for (i = 0; i < dump_save_areas.count; i++) {
                prefix = dump_save_areas.areas[i]->pref_reg;
                hdr->real_cpu_cnt++;
                if (!prefix)
                        continue;
                hdr->lc_vec[hdr->cpu_cnt] = prefix;
                hdr->cpu_cnt++;
        }
}

/*
 * Provide IPL parameter information block from either HSA or memory
 * for future reipl
 */
static int __init zcore_reipl_init(void)
{
        struct ipib_info ipib_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;
        ipl_block = (void *) __get_free_page(GFP_KERNEL);
        if (!ipl_block)
                return -ENOMEM;
        if (ipib_info.ipib < sclp_get_hsa_size())
                rc = memcpy_hsa_kernel(ipl_block, ipib_info.ipib, PAGE_SIZE);
        else
                rc = memcpy_real(ipl_block, (void *) ipib_info.ipib, PAGE_SIZE);
        if (rc || csum_partial(ipl_block, ipl_block->hdr.len, 0) !=
            ipib_info.checksum) {
                TRACE("Checksum does not match\n");
                free_page((unsigned long) ipl_block);
                ipl_block = NULL;
        }
        return 0;
}

static int __init zcore_init(void)
{
        unsigned long mem_size, mem_end;
        unsigned char arch;
        int rc;

        mem_size = mem_end = 0;
        if (ipl_info.type != IPL_TYPE_FCP_DUMP)
                return -ENODATA;
        if (OLDMEM_BASE)
                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);

        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);

        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;

#ifdef CONFIG_64BIT
        if (arch == ARCH_S390) {
                pr_alert("The 64-bit dump tool cannot be used for a "
                         "32-bit system\n");
                rc = -EINVAL;
                goto fail;
        }
#else /* CONFIG_64BIT */
        if (arch == ARCH_S390X) {
                pr_alert("The 32-bit dump tool cannot be used for a "
                         "64-bit system\n");
                rc = -EINVAL;
                goto fail;
        }
#endif /* CONFIG_64BIT */

        rc = get_mem_info(&mem_size, &mem_end);
        if (rc)
                goto fail;

        rc = sys_info_init(arch, mem_end);
        if (rc)
                goto fail;
        zcore_header_init(arch, &zcore_header, mem_size);

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

        zcore_dir = debugfs_create_dir("zcore" , NULL);
        if (!zcore_dir) {
                rc = -ENOMEM;
                goto fail;
        }
        zcore_file = debugfs_create_file("mem", S_IRUSR, zcore_dir, NULL,
                                         &zcore_fops);
        if (!zcore_file) {
                rc = -ENOMEM;
                goto fail_dir;
        }
        zcore_memmap_file = debugfs_create_file("memmap", S_IRUSR, zcore_dir,
                                                NULL, &zcore_memmap_fops);
        if (!zcore_memmap_file) {
                rc = -ENOMEM;
                goto fail_file;
        }
        zcore_reipl_file = debugfs_create_file("reipl", S_IRUSR, zcore_dir,
                                                NULL, &zcore_reipl_fops);
        if (!zcore_reipl_file) {
                rc = -ENOMEM;
                goto fail_memmap_file;
        }
        zcore_hsa_file = debugfs_create_file("hsa", S_IRUSR|S_IWUSR, zcore_dir,
                                             NULL, &zcore_hsa_fops);
        if (!zcore_hsa_file) {
                rc = -ENOMEM;
                goto fail_reipl_file;
        }
        return 0;

fail_reipl_file:
        debugfs_remove(zcore_reipl_file);
fail_memmap_file:
        debugfs_remove(zcore_memmap_file);
fail_file:
        debugfs_remove(zcore_file);
fail_dir:
        debugfs_remove(zcore_dir);
fail:
        diag308(DIAG308_REL_HSA, NULL);
        return rc;
}

static void __exit zcore_exit(void)
{
        debug_unregister(zcore_dbf);
        sclp_sdias_exit();
        free_page((unsigned long) ipl_block);
        debugfs_remove(zcore_hsa_file);
        debugfs_remove(zcore_reipl_file);
        debugfs_remove(zcore_memmap_file);
        debugfs_remove(zcore_file);
        debugfs_remove(zcore_dir);
        diag308(DIAG308_REL_HSA, NULL);
}

MODULE_AUTHOR("Copyright IBM Corp. 2003,2008");
MODULE_DESCRIPTION("zcore module for zfcpdump support");
MODULE_LICENSE("GPL");

subsys_initcall(zcore_init);
module_exit(zcore_exit);