/*
 * File...........: arch/s390/mm/extmem.c
 * Author(s)......: Carsten Otte <cotte@de.ibm.com>
 *                  Rob M van der Heij <rvdheij@nl.ibm.com>
 *                  Steven Shultz <shultzss@us.ibm.com>
 * Bugreports.to..: <Linux390@de.ibm.com>
 * (C) IBM Corporation 2002-2004
 */

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/bootmem.h>
#include <asm/page.h>
#include <asm/ebcdic.h>
#include <asm/errno.h>
#include <asm/extmem.h>
#include <asm/cpcmd.h>
#include <linux/ctype.h>

#define DCSS_DEBUG      /* Debug messages on/off */

#define DCSS_NAME "extmem"
#ifdef DCSS_DEBUG
#define PRINT_DEBUG(x...)       printk(KERN_DEBUG DCSS_NAME " debug:" x)
#else
#define PRINT_DEBUG(x...)   do {} while (0)
#endif
#define PRINT_INFO(x...)        printk(KERN_INFO DCSS_NAME " info:" x)
#define PRINT_WARN(x...)        printk(KERN_WARNING DCSS_NAME " warning:" x)
#define PRINT_ERR(x...)         printk(KERN_ERR DCSS_NAME " error:" x)


#define DCSS_LOADSHR    0x00
#define DCSS_LOADNSR    0x04
#define DCSS_PURGESEG   0x08
#define DCSS_FINDSEG    0x0c
#define DCSS_LOADNOLY   0x10
#define DCSS_SEGEXT     0x18
#define DCSS_FINDSEGA   0x0c

struct qrange {
        unsigned int  start; // 3byte start address, 1 byte type
        unsigned int  end;   // 3byte end address, 1 byte reserved
};

struct qout64 {
        int segstart;
        int segend;
        int segcnt;
        int segrcnt;
        struct qrange range[6];
};

struct qin64 {
        char qopcode;
        char rsrv1[3];
        char qrcode;
        char rsrv2[3];
        char qname[8];
        unsigned int qoutptr;
        short int qoutlen;
};

struct dcss_segment {
        struct list_head list;
        char dcss_name[8];
        unsigned long start_addr;
        unsigned long end;
        atomic_t ref_count;
        int do_nonshared;
        unsigned int vm_segtype;
        struct qrange range[6];
        int segcnt;
};

static DEFINE_SPINLOCK(dcss_lock);
static struct list_head dcss_list = LIST_HEAD_INIT(dcss_list);
static char *segtype_string[] = { "SW", "EW", "SR", "ER", "SN", "EN", "SC",
                                        "EW/EN-MIXED" };

extern struct {
        unsigned long addr, size, type;
} memory_chunk[MEMORY_CHUNKS];

/*
 * Create the 8 bytes, ebcdic VM segment name from
 * an ascii name.
 */
static void inline
dcss_mkname(char *name, char *dcss_name)
{
        int i;

        for (i = 0; i < 8; i++) {
                if (name[i] == '\0')
                        break;
                dcss_name[i] = toupper(name[i]);
        };
        for (; i < 8; i++)
                dcss_name[i] = ' ';
        ASCEBC(dcss_name, 8);
}


/*
 * search all segments in dcss_list, and return the one
 * namend *name. If not found, return NULL.
 */
static struct dcss_segment *
segment_by_name (char *name)
{
        char dcss_name[9];
        struct list_head *l;
        struct dcss_segment *tmp, *retval = NULL;

        assert_spin_locked(&dcss_lock);
        dcss_mkname (name, dcss_name);
        list_for_each (l, &dcss_list) {
                tmp = list_entry (l, struct dcss_segment, list);
                if (memcmp(tmp->dcss_name, dcss_name, 8) == 0) {
                        retval = tmp;
                        break;
                }
        }
        return retval;
}


/*
 * Perform a function on a dcss segment.
 */
static inline int
dcss_diag (__u8 func, void *parameter,
           unsigned long *ret1, unsigned long *ret2)
{
        unsigned long rx, ry;
        int rc;

        rx = (unsigned long) parameter;
        ry = (unsigned long) func;
        __asm__ __volatile__(
#ifdef CONFIG_ARCH_S390X
                "   sam31\n" // switch to 31 bit
                "   diag    %0,%1,0x64\n"
                "   sam64\n" // switch back to 64 bit
#else
                "   diag    %0,%1,0x64\n"
#endif
                "   ipm     %2\n"
                "   srl     %2,28\n"
                : "+d" (rx), "+d" (ry), "=d" (rc) : : "cc" );
        *ret1 = rx;
        *ret2 = ry;
        return rc;
}

static inline int
dcss_diag_translate_rc (int vm_rc) {
        if (vm_rc == 44)
                return -ENOENT;
        return -EIO;
}


/* do a diag to get info about a segment.
 * fills start_address, end and vm_segtype fields
 */
static int
query_segment_type (struct dcss_segment *seg)
{
        struct qin64  *qin = kmalloc (sizeof(struct qin64), GFP_DMA);
        struct qout64 *qout = kmalloc (sizeof(struct qout64), GFP_DMA);

        int diag_cc, rc, i;
        unsigned long dummy, vmrc;

        if ((qin == NULL) || (qout == NULL)) {
                rc = -ENOMEM;
                goto out_free;
        }

        /* initialize diag input parameters */
        qin->qopcode = DCSS_FINDSEGA;
        qin->qoutptr = (unsigned long) qout;
        qin->qoutlen = sizeof(struct qout64);
        memcpy (qin->qname, seg->dcss_name, 8);

        diag_cc = dcss_diag (DCSS_SEGEXT, qin, &dummy, &vmrc);

        if (diag_cc > 1) {
                rc = dcss_diag_translate_rc (vmrc);
                goto out_free;
        }

        if (qout->segcnt > 6) {
                rc = -ENOTSUPP;
                goto out_free;
        }

        if (qout->segcnt == 1) {
                seg->vm_segtype = qout->range[0].start & 0xff;
        } else {
                /* multi-part segment. only one type supported here:
                    - all parts are contiguous
                    - all parts are either EW or EN type
                    - maximum 6 parts allowed */
                unsigned long start = qout->segstart >> PAGE_SHIFT;
                for (i=0; i<qout->segcnt; i++) {
                        if (((qout->range[i].start & 0xff) != SEG_TYPE_EW) &&
                            ((qout->range[i].start & 0xff) != SEG_TYPE_EN)) {
                                rc = -ENOTSUPP;
                                goto out_free;
                        }
                        if (start != qout->range[i].start >> PAGE_SHIFT) {
                                rc = -ENOTSUPP;
                                goto out_free;
                        }
                        start = (qout->range[i].end >> PAGE_SHIFT) + 1;
                }
                seg->vm_segtype = SEG_TYPE_EWEN;
        }

        /* analyze diag output and update seg */
        seg->start_addr = qout->segstart;
        seg->end = qout->segend;

        memcpy (seg->range, qout->range, 6*sizeof(struct qrange));
        seg->segcnt = qout->segcnt;

        rc = 0;

 out_free:
        if (qin) kfree(qin);
        if (qout) kfree(qout);
        return rc;
}

/*
 * check if the given segment collides with guest storage.
 * returns 1 if this is the case, 0 if no collision was found
 */
static int
segment_overlaps_storage(struct dcss_segment *seg)
{
        int i;

        for (i=0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
                if (memory_chunk[i].type != 0)
                        continue;
                if ((memory_chunk[i].addr >> 20) > (seg->end >> 20))
                        continue;
                if (((memory_chunk[i].addr + memory_chunk[i].size - 1) >> 20)
                                < (seg->start_addr >> 20))
                        continue;
                return 1;
        }
        return 0;
}

/*
 * check if segment collides with other segments that are currently loaded
 * returns 1 if this is the case, 0 if no collision was found
 */
static int
segment_overlaps_others (struct dcss_segment *seg)
{
        struct list_head *l;
        struct dcss_segment *tmp;

        assert_spin_locked(&dcss_lock);
        list_for_each(l, &dcss_list) {
                tmp = list_entry(l, struct dcss_segment, list);
                if ((tmp->start_addr >> 20) > (seg->end >> 20))
                        continue;
                if ((tmp->end >> 20) < (seg->start_addr >> 20))
                        continue;
                if (seg == tmp)
                        continue;
                return 1;
        }
        return 0;
}

/*
 * check if segment exceeds the kernel mapping range (detected or set via mem=)
 * returns 1 if this is the case, 0 if segment fits into the range
 */
static inline int
segment_exceeds_range (struct dcss_segment *seg)
{
        int seg_last_pfn = (seg->end) >> PAGE_SHIFT;
        if (seg_last_pfn > max_pfn)
                return 1;
        return 0;
}

/*
 * get info about a segment
 * possible return values:
 * -ENOSYS  : we are not running on VM
 * -EIO     : could not perform query diagnose
 * -ENOENT  : no such segment
 * -ENOTSUPP: multi-part segment cannot be used with linux
 * -ENOSPC  : segment cannot be used (overlaps with storage)
 * -ENOMEM  : out of memory
 * 0 .. 6   : type of segment as defined in include/asm-s390/extmem.h
 */
int
segment_type (char* name)
{
        int rc;
        struct dcss_segment seg;

        if (!MACHINE_IS_VM)
                return -ENOSYS;

        dcss_mkname(name, seg.dcss_name);
        rc = query_segment_type (&seg);
        if (rc < 0)
                return rc;
        return seg.vm_segtype;
}

/*
 * real segment loading function, called from segment_load
 */
static int
__segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long *end)
{
        struct dcss_segment *seg = kmalloc(sizeof(struct dcss_segment),
                        GFP_DMA);
        int dcss_command, rc, diag_cc;

        if (seg == NULL) {
                rc = -ENOMEM;
                goto out;
        }
        dcss_mkname (name, seg->dcss_name);
        rc = query_segment_type (seg);
        if (rc < 0)
                goto out_free;
        if (segment_exceeds_range(seg)) {
                PRINT_WARN ("segment_load: not loading segment %s - exceeds"
                                " kernel mapping range\n",name);
                rc = -ERANGE;
                goto out_free;
        }
        if (segment_overlaps_storage(seg)) {
                PRINT_WARN ("segment_load: not loading segment %s - overlaps"
                                " storage\n",name);
                rc = -ENOSPC;
                goto out_free;
        }
        if (segment_overlaps_others(seg)) {
                PRINT_WARN ("segment_load: not loading segment %s - overlaps"
                                " other segments\n",name);
                rc = -EBUSY;
                goto out_free;
        }
        if (do_nonshared)
                dcss_command = DCSS_LOADNSR;
        else
                dcss_command = DCSS_LOADNOLY;

        diag_cc = dcss_diag(dcss_command, seg->dcss_name,
                        &seg->start_addr, &seg->end);
        if (diag_cc > 1) {
                PRINT_WARN ("segment_load: could not load segment %s - "
                                "diag returned error (%ld)\n",name,seg->end);
                rc = dcss_diag_translate_rc (seg->end);
                dcss_diag(DCSS_PURGESEG, seg->dcss_name,
                                &seg->start_addr, &seg->end);
                goto out_free;
        }
        seg->do_nonshared = do_nonshared;
        atomic_set(&seg->ref_count, 1);
        list_add(&seg->list, &dcss_list);
        rc = seg->vm_segtype;
        *addr = seg->start_addr;
        *end  = seg->end;
        if (do_nonshared)
                PRINT_INFO ("segment_load: loaded segment %s range %p .. %p "
                                "type %s in non-shared mode\n", name,
                                (void*)seg->start_addr, (void*)seg->end,
                                segtype_string[seg->vm_segtype]);
        else
                PRINT_INFO ("segment_load: loaded segment %s range %p .. %p "
                                "type %s in shared mode\n", name,
                                (void*)seg->start_addr, (void*)seg->end,
                                segtype_string[seg->vm_segtype]);
        goto out;
 out_free:
        kfree (seg);
 out:
        return rc;
}

/*
 * this function loads a DCSS segment
 * name         : name of the DCSS
 * do_nonshared : 0 indicates that the dcss should be shared with other linux images
 *                1 indicates that the dcss should be exclusive for this linux image
 * addr         : will be filled with start address of the segment
 * end          : will be filled with end address of the segment
 * return values:
 * -ENOSYS  : we are not running on VM
 * -EIO     : could not perform query or load diagnose
 * -ENOENT  : no such segment
 * -ENOTSUPP: multi-part segment cannot be used with linux
 * -ENOSPC  : segment cannot be used (overlaps with storage)
 * -EBUSY   : segment can temporarily not be used (overlaps with dcss)
 * -ERANGE  : segment cannot be used (exceeds kernel mapping range)
 * -EPERM   : segment is currently loaded with incompatible permissions
 * -ENOMEM  : out of memory
 * 0 .. 6   : type of segment as defined in include/asm-s390/extmem.h
 */
int
segment_load (char *name, int do_nonshared, unsigned long *addr,
                unsigned long *end)
{
        struct dcss_segment *seg;
        int rc;

        if (!MACHINE_IS_VM)
                return -ENOSYS;

        spin_lock (&dcss_lock);
        seg = segment_by_name (name);
        if (seg == NULL)
                rc = __segment_load (name, do_nonshared, addr, end);
        else {
                if (do_nonshared == seg->do_nonshared) {
                        atomic_inc(&seg->ref_count);
                        *addr = seg->start_addr;
                        *end  = seg->end;
                        rc    = seg->vm_segtype;
                } else {
                        *addr = *end = 0;
                        rc    = -EPERM;
                }
        }
        spin_unlock (&dcss_lock);
        return rc;
}

/*
 * this function modifies the shared state of a DCSS segment. note that
 * name         : name of the DCSS
 * do_nonshared : 0 indicates that the dcss should be shared with other linux images
 *                1 indicates that the dcss should be exclusive for this linux image
 * return values:
 * -EIO     : could not perform load diagnose (segment gone!)
 * -ENOENT  : no such segment (segment gone!)
 * -EAGAIN  : segment is in use by other exploiters, try later
 * -EINVAL  : no segment with the given name is currently loaded - name invalid
 * 0        : operation succeeded
 */
int
segment_modify_shared (char *name, int do_nonshared)
{
        struct dcss_segment *seg;
        unsigned long dummy;
        int dcss_command, rc, diag_cc;

        spin_lock (&dcss_lock);
        seg = segment_by_name (name);
        if (seg == NULL) {
                rc = -EINVAL;
                goto out_unlock;
        }
        if (do_nonshared == seg->do_nonshared) {
                PRINT_INFO ("segment_modify_shared: not reloading segment %s"
                                " - already in requested mode\n",name);
                rc = 0;
                goto out_unlock;
        }
        if (atomic_read (&seg->ref_count) != 1) {
                PRINT_WARN ("segment_modify_shared: not reloading segment %s - "
                                "segment is in use by other driver(s)\n",name);
                rc = -EAGAIN;
                goto out_unlock;
        }
        dcss_diag(DCSS_PURGESEG, seg->dcss_name,
                  &dummy, &dummy);
        if (do_nonshared)
                dcss_command = DCSS_LOADNSR;
        else
        dcss_command = DCSS_LOADNOLY;
        diag_cc = dcss_diag(dcss_command, seg->dcss_name,
                        &seg->start_addr, &seg->end);
        if (diag_cc > 1) {
                PRINT_WARN ("segment_modify_shared: could not reload segment %s"
                                " - diag returned error (%ld)\n",name,seg->end);
                rc = dcss_diag_translate_rc (seg->end);
                goto out_del;
        }
        seg->do_nonshared = do_nonshared;
        rc = 0;
        goto out_unlock;
 out_del:
        list_del(&seg->list);
        dcss_diag(DCSS_PURGESEG, seg->dcss_name,
                  &dummy, &dummy);
        kfree (seg);
 out_unlock:
        spin_unlock(&dcss_lock);
        return rc;
}

/*
 * Decrease the use count of a DCSS segment and remove
 * it from the address space if nobody is using it
 * any longer.
 */
void
segment_unload(char *name)
{
        unsigned long dummy;
        struct dcss_segment *seg;

        if (!MACHINE_IS_VM)
                return;

        spin_lock(&dcss_lock);
        seg = segment_by_name (name);
        if (seg == NULL) {
                PRINT_ERR ("could not find segment %s in segment_unload, "
                                "please report to linux390@de.ibm.com\n",name);
                goto out_unlock;
        }
        if (atomic_dec_return(&seg->ref_count) == 0) {
                list_del(&seg->list);
                dcss_diag(DCSS_PURGESEG, seg->dcss_name,
                          &dummy, &dummy);
                kfree(seg);
        }
out_unlock:
        spin_unlock(&dcss_lock);
}

/*
 * save segment content permanently
 */
void
segment_save(char *name)
{
        struct dcss_segment *seg;
        int startpfn = 0;
        int endpfn = 0;
        char cmd1[160];
        char cmd2[80];
        int i;

        if (!MACHINE_IS_VM)
                return;

        spin_lock(&dcss_lock);
        seg = segment_by_name (name);

        if (seg == NULL) {
                PRINT_ERR ("could not find segment %s in segment_save, please report to linux390@de.ibm.com\n",name);
                return;
        }

        startpfn = seg->start_addr >> PAGE_SHIFT;
        endpfn = (seg->end) >> PAGE_SHIFT;
        sprintf(cmd1, "DEFSEG %s", name);
        for (i=0; i<seg->segcnt; i++) {
                sprintf(cmd1+strlen(cmd1), " %X-%X %s",
                        seg->range[i].start >> PAGE_SHIFT,
                        seg->range[i].end >> PAGE_SHIFT,
                        segtype_string[seg->range[i].start & 0xff]);
        }
        sprintf(cmd2, "SAVESEG %s", name);
        cpcmd(cmd1, NULL, 0);
        cpcmd(cmd2, NULL, 0);
        spin_unlock(&dcss_lock);
}

EXPORT_SYMBOL(segment_load);
EXPORT_SYMBOL(segment_unload);
EXPORT_SYMBOL(segment_save);
EXPORT_SYMBOL(segment_type);
EXPORT_SYMBOL(segment_modify_shared);