// SPDX-License-Identifier: GPL-2.0
/*
 * 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>
 * Copyright IBM Corp. 2002, 2004
 */

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

#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <linux/bootmem.h>
#include <linux/ctype.h>
#include <linux/ioport.h>
#include <asm/diag.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/ebcdic.h>
#include <asm/errno.h>
#include <asm/extmem.h>
#include <asm/cpcmd.h>
#include <asm/setup.h>

#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_LOADSHRX   0x20
#define DCSS_LOADNSRX   0x24
#define DCSS_FINDSEGX   0x2c
#define DCSS_SEGEXTX    0x38
#define DCSS_FINDSEGA   0x0c

struct qrange {
        unsigned long  start; /* last byte type */
        unsigned long  end;   /* last byte reserved */
};

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

struct qrange_old {
        unsigned int start; /* last byte type */
        unsigned int end;   /* last byte reserved */
};

/* output area format for the Diag x'64' old subcode x'18' */
struct qout64_old {
        int segstart;
        int segend;
        int segcnt;
        int segrcnt;
        struct qrange_old 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];
        char res_name[16];
        unsigned long start_addr;
        unsigned long end;
        atomic_t ref_count;
        int do_nonshared;
        unsigned int vm_segtype;
        struct qrange range[6];
        int segcnt;
        struct resource *res;
};

static DEFINE_MUTEX(dcss_lock);
static LIST_HEAD(dcss_list);
static char *segtype_string[] = { "SW", "EW", "SR", "ER", "SN", "EN", "SC",
                                        "EW/EN-MIXED" };
static int loadshr_scode, loadnsr_scode;
static int segext_scode, purgeseg_scode;
static int scode_set;

/* set correct Diag x'64' subcodes. */
static int
dcss_set_subcodes(void)
{
        char *name = kmalloc(8, GFP_KERNEL | GFP_DMA);
        unsigned long rx, ry;
        int rc;

        if (name == NULL)
                return -ENOMEM;

        rx = (unsigned long) name;
        ry = DCSS_FINDSEGX;

        strcpy(name, "dummy");
        diag_stat_inc(DIAG_STAT_X064);
        asm volatile(
                "       diag    %0,%1,0x64\n"
                "0:     ipm     %2\n"
                "       srl     %2,28\n"
                "       j       2f\n"
                "1:     la      %2,3\n"
                "2:\n"
                EX_TABLE(0b, 1b)
                : "+d" (rx), "+d" (ry), "=d" (rc) : : "cc", "memory");

        kfree(name);
        /* Diag x'64' new subcodes are supported, set to new subcodes */
        if (rc != 3) {
                loadshr_scode = DCSS_LOADSHRX;
                loadnsr_scode = DCSS_LOADNSRX;
                purgeseg_scode = DCSS_PURGESEG;
                segext_scode = DCSS_SEGEXTX;
                return 0;
        }
        /* Diag x'64' new subcodes are not supported, set to old subcodes */
        loadshr_scode = DCSS_LOADNOLY;
        loadnsr_scode = DCSS_LOADNSR;
        purgeseg_scode = DCSS_PURGESEG;
        segext_scode = DCSS_SEGEXT;
        return 0;
}

/*
 * Create the 8 bytes, ebcdic VM segment name from
 * an ascii name.
 */
static void
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;

        BUG_ON(!mutex_is_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(int *func, void *parameter,
           unsigned long *ret1, unsigned long *ret2)
{
        unsigned long rx, ry;
        int rc;

        if (scode_set == 0) {
                rc = dcss_set_subcodes();
                if (rc < 0)
                        return rc;
                scode_set = 1;
        }
        rx = (unsigned long) parameter;
        ry = (unsigned long) *func;

        /* 64-bit Diag x'64' new subcode, keep in 64-bit addressing mode */
        diag_stat_inc(DIAG_STAT_X064);
        if (*func > DCSS_SEGEXT)
                asm volatile(
                        "       diag    %0,%1,0x64\n"
                        "       ipm     %2\n"
                        "       srl     %2,28\n"
                        : "+d" (rx), "+d" (ry), "=d" (rc) : : "cc");
        /* 31-bit Diag x'64' old subcode, switch to 31-bit addressing mode */
        else
                asm volatile(
                        "       sam31\n"
                        "       diag    %0,%1,0x64\n"
                        "       sam64\n"
                        "       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)
{
        unsigned long dummy, vmrc;
        int diag_cc, rc, i;
        struct qout64 *qout;
        struct qin64 *qin;

        qin = kmalloc(sizeof(*qin), GFP_KERNEL | GFP_DMA);
        qout = kmalloc(sizeof(*qout), GFP_KERNEL | GFP_DMA);
        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(&segext_scode, qin, &dummy, &vmrc);

        if (diag_cc < 0) {
                rc = diag_cc;
                goto out_free;
        }
        if (diag_cc > 1) {
                pr_warn("Querying a DCSS type failed with rc=%ld\n", vmrc);
                rc = dcss_diag_translate_rc (vmrc);
                goto out_free;
        }

        /* Only old format of output area of Diagnose x'64' is supported,
           copy data for the new format. */
        if (segext_scode == DCSS_SEGEXT) {
                struct qout64_old *qout_old;
                qout_old = kzalloc(sizeof(*qout_old), GFP_KERNEL | GFP_DMA);
                if (qout_old == NULL) {
                        rc = -ENOMEM;
                        goto out_free;
                }
                memcpy(qout_old, qout, sizeof(struct qout64_old));
                qout->segstart = (unsigned long) qout_old->segstart;
                qout->segend = (unsigned long) qout_old->segend;
                qout->segcnt = qout_old->segcnt;
                qout->segrcnt = qout_old->segrcnt;

                if (qout->segcnt > 6)
                        qout->segrcnt = 6;
                for (i = 0; i < qout->segrcnt; i++) {
                        qout->range[i].start =
                                (unsigned long) qout_old->range[i].start;
                        qout->range[i].end =
                                (unsigned long) qout_old->range[i].end;
                }
                kfree(qout_old);
        }
        if (qout->segcnt > 6) {
                rc = -EOPNOTSUPP;
                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 = -EOPNOTSUPP;
                                goto out_free;
                        }
                        if (start != qout->range[i].start >> PAGE_SHIFT) {
                                rc = -EOPNOTSUPP;
                                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:
        kfree(qin);
        kfree(qout);
        return rc;
}

/*
 * 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
 * -EOPNOTSUPP: multi-part segment cannot be used with linux
 * -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;
}

/*
 * 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;

        BUG_ON(!mutex_is_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;
}

/*
 * real segment loading function, called from segment_load
 */
static int
__segment_load (char *name, int do_nonshared, unsigned long *addr, unsigned long *end)
{
        unsigned long start_addr, end_addr, dummy;
        struct dcss_segment *seg;
        int rc, diag_cc;

        start_addr = end_addr = 0;
        seg = kmalloc(sizeof(*seg), GFP_KERNEL | GFP_DMA);
        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 (loadshr_scode == DCSS_LOADSHRX) {
                if (segment_overlaps_others(seg)) {
                        rc = -EBUSY;
                        goto out_free;
                }
        }

        rc = vmem_add_mapping(seg->start_addr, seg->end - seg->start_addr + 1);

        if (rc)
                goto out_free;

        seg->res = kzalloc(sizeof(struct resource), GFP_KERNEL);
        if (seg->res == NULL) {
                rc = -ENOMEM;
                goto out_shared;
        }
        seg->res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
        seg->res->start = seg->start_addr;
        seg->res->end = seg->end;
        memcpy(&seg->res_name, seg->dcss_name, 8);
        EBCASC(seg->res_name, 8);
        seg->res_name[8] = '\0';
        strlcat(seg->res_name, " (DCSS)", sizeof(seg->res_name));
        seg->res->name = seg->res_name;
        rc = seg->vm_segtype;
        if (rc == SEG_TYPE_SC ||
            ((rc == SEG_TYPE_SR || rc == SEG_TYPE_ER) && !do_nonshared))
                seg->res->flags |= IORESOURCE_READONLY;
        if (request_resource(&iomem_resource, seg->res)) {
                rc = -EBUSY;
                kfree(seg->res);
                goto out_shared;
        }

        if (do_nonshared)
                diag_cc = dcss_diag(&loadnsr_scode, seg->dcss_name,
                                &start_addr, &end_addr);
        else
                diag_cc = dcss_diag(&loadshr_scode, seg->dcss_name,
                                &start_addr, &end_addr);
        if (diag_cc < 0) {
                dcss_diag(&purgeseg_scode, seg->dcss_name,
                                &dummy, &dummy);
                rc = diag_cc;
                goto out_resource;
        }
        if (diag_cc > 1) {
                pr_warn("Loading DCSS %s failed with rc=%ld\n", name, end_addr);
                rc = dcss_diag_translate_rc(end_addr);
                dcss_diag(&purgeseg_scode, seg->dcss_name,
                                &dummy, &dummy);
                goto out_resource;
        }
        seg->start_addr = start_addr;
        seg->end = end_addr;
        seg->do_nonshared = do_nonshared;
        atomic_set(&seg->ref_count, 1);
        list_add(&seg->list, &dcss_list);
        *addr = seg->start_addr;
        *end  = seg->end;
        if (do_nonshared)
                pr_info("DCSS %s of range %p to %p and type %s loaded as "
                        "exclusive-writable\n", name, (void*) seg->start_addr,
                        (void*) seg->end, segtype_string[seg->vm_segtype]);
        else {
                pr_info("DCSS %s of range %p to %p and type %s loaded in "
                        "shared access mode\n", name, (void*) seg->start_addr,
                        (void*) seg->end, segtype_string[seg->vm_segtype]);
        }
        goto out;
 out_resource:
        release_resource(seg->res);
        kfree(seg->res);
 out_shared:
        vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
 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
 * -EOPNOTSUPP: 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;

        mutex_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;
                }
        }
        mutex_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
 * -EBUSY   : segment can temporarily not be used (overlaps with dcss)
 * 0        : operation succeeded
 */
int
segment_modify_shared (char *name, int do_nonshared)
{
        struct dcss_segment *seg;
        unsigned long start_addr, end_addr, dummy;
        int rc, diag_cc;

        start_addr = end_addr = 0;
        mutex_lock(&dcss_lock);
        seg = segment_by_name (name);
        if (seg == NULL) {
                rc = -EINVAL;
                goto out_unlock;
        }
        if (do_nonshared == seg->do_nonshared) {
                pr_info("DCSS %s is already in the requested access "
                        "mode\n", name);
                rc = 0;
                goto out_unlock;
        }
        if (atomic_read (&seg->ref_count) != 1) {
                pr_warn("DCSS %s is in use and cannot be reloaded\n", name);
                rc = -EAGAIN;
                goto out_unlock;
        }
        release_resource(seg->res);
        if (do_nonshared)
                seg->res->flags &= ~IORESOURCE_READONLY;
        else
                if (seg->vm_segtype == SEG_TYPE_SR ||
                    seg->vm_segtype == SEG_TYPE_ER)
                        seg->res->flags |= IORESOURCE_READONLY;

        if (request_resource(&iomem_resource, seg->res)) {
                pr_warn("DCSS %s overlaps with used memory resources and cannot be reloaded\n",
                        name);
                rc = -EBUSY;
                kfree(seg->res);
                goto out_del_mem;
        }

        dcss_diag(&purgeseg_scode, seg->dcss_name, &dummy, &dummy);
        if (do_nonshared)
                diag_cc = dcss_diag(&loadnsr_scode, seg->dcss_name,
                                &start_addr, &end_addr);
        else
                diag_cc = dcss_diag(&loadshr_scode, seg->dcss_name,
                                &start_addr, &end_addr);
        if (diag_cc < 0) {
                rc = diag_cc;
                goto out_del_res;
        }
        if (diag_cc > 1) {
                pr_warn("Reloading DCSS %s failed with rc=%ld\n",
                        name, end_addr);
                rc = dcss_diag_translate_rc(end_addr);
                goto out_del_res;
        }
        seg->start_addr = start_addr;
        seg->end = end_addr;
        seg->do_nonshared = do_nonshared;
        rc = 0;
        goto out_unlock;
 out_del_res:
        release_resource(seg->res);
        kfree(seg->res);
 out_del_mem:
        vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
        list_del(&seg->list);
        dcss_diag(&purgeseg_scode, seg->dcss_name, &dummy, &dummy);
        kfree(seg);
 out_unlock:
        mutex_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;

        mutex_lock(&dcss_lock);
        seg = segment_by_name (name);
        if (seg == NULL) {
                pr_err("Unloading unknown DCSS %s failed\n", name);
                goto out_unlock;
        }
        if (atomic_dec_return(&seg->ref_count) != 0)
                goto out_unlock;
        release_resource(seg->res);
        kfree(seg->res);
        vmem_remove_mapping(seg->start_addr, seg->end - seg->start_addr + 1);
        list_del(&seg->list);
        dcss_diag(&purgeseg_scode, seg->dcss_name, &dummy, &dummy);
        kfree(seg);
out_unlock:
        mutex_unlock(&dcss_lock);
}

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

        if (!MACHINE_IS_VM)
                return;

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

        if (seg == NULL) {
                pr_err("Saving unknown DCSS %s failed\n", name);
                goto out;
        }

        sprintf(cmd1, "DEFSEG %s", name);
        for (i=0; i<seg->segcnt; i++) {
                sprintf(cmd1+strlen(cmd1), " %lX-%lX %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);
        response = 0;
        cpcmd(cmd1, NULL, 0, &response);
        if (response) {
                pr_err("Saving a DCSS failed with DEFSEG response code "
                       "%i\n", response);
                goto out;
        }
        cpcmd(cmd2, NULL, 0, &response);
        if (response) {
                pr_err("Saving a DCSS failed with SAVESEG response code "
                       "%i\n", response);
                goto out;
        }
out:
        mutex_unlock(&dcss_lock);
}

/*
 * print appropriate error message for segment_load()/segment_type()
 * return code
 */
void segment_warning(int rc, char *seg_name)
{
        switch (rc) {
        case -ENOENT:
                pr_err("DCSS %s cannot be loaded or queried\n", seg_name);
                break;
        case -ENOSYS:
                pr_err("DCSS %s cannot be loaded or queried without "
                       "z/VM\n", seg_name);
                break;
        case -EIO:
                pr_err("Loading or querying DCSS %s resulted in a "
                       "hardware error\n", seg_name);
                break;
        case -EOPNOTSUPP:
                pr_err("DCSS %s has multiple page ranges and cannot be "
                       "loaded or queried\n", seg_name);
                break;
        case -ENOSPC:
                pr_err("DCSS %s overlaps with used storage and cannot "
                       "be loaded\n", seg_name);
                break;
        case -EBUSY:
                pr_err("%s needs used memory resources and cannot be "
                       "loaded or queried\n", seg_name);
                break;
        case -EPERM:
                pr_err("DCSS %s is already loaded in a different access "
                       "mode\n", seg_name);
                break;
        case -ENOMEM:
                pr_err("There is not enough memory to load or query "
                       "DCSS %s\n", seg_name);
                break;
        case -ERANGE:
                pr_err("DCSS %s exceeds the kernel mapping range (%lu) "
                       "and cannot be loaded\n", seg_name, VMEM_MAX_PHYS);
                break;
        default:
                break;
        }
}

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