linux/drivers/char/mspec.c
<<
>>
Prefs
   1/*
   2 * Copyright (C) 2001-2006 Silicon Graphics, Inc.  All rights
   3 * reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms of version 2 of the GNU General Public License
   7 * as published by the Free Software Foundation.
   8 */
   9
  10/*
  11 * SN Platform Special Memory (mspec) Support
  12 *
  13 * This driver exports the SN special memory (mspec) facility to user
  14 * processes.
  15 * There are three types of memory made available thru this driver:
  16 * fetchops, uncached and cached.
  17 *
  18 * Fetchops are atomic memory operations that are implemented in the
  19 * memory controller on SGI SN hardware.
  20 *
  21 * Uncached are used for memory write combining feature of the ia64
  22 * cpu.
  23 *
  24 * Cached are used for areas of memory that are used as cached addresses
  25 * on our partition and used as uncached addresses from other partitions.
  26 * Due to a design constraint of the SN2 Shub, you can not have processors
  27 * on the same FSB perform both a cached and uncached reference to the
  28 * same cache line.  These special memory cached regions prevent the
  29 * kernel from ever dropping in a TLB entry and therefore prevent the
  30 * processor from ever speculating a cache line from this page.
  31 */
  32
  33#include <linux/types.h>
  34#include <linux/kernel.h>
  35#include <linux/module.h>
  36#include <linux/init.h>
  37#include <linux/errno.h>
  38#include <linux/miscdevice.h>
  39#include <linux/spinlock.h>
  40#include <linux/mm.h>
  41#include <linux/fs.h>
  42#include <linux/vmalloc.h>
  43#include <linux/string.h>
  44#include <linux/slab.h>
  45#include <linux/numa.h>
  46#include <asm/page.h>
  47#include <asm/pgtable.h>
  48#include <linux/atomic.h>
  49#include <asm/tlbflush.h>
  50#include <asm/uncached.h>
  51#include <asm/sn/addrs.h>
  52#include <asm/sn/arch.h>
  53#include <asm/sn/mspec.h>
  54#include <asm/sn/sn_cpuid.h>
  55#include <asm/sn/io.h>
  56#include <asm/sn/bte.h>
  57#include <asm/sn/shubio.h>
  58
  59
  60#define FETCHOP_ID      "SGI Fetchop,"
  61#define CACHED_ID       "Cached,"
  62#define UNCACHED_ID     "Uncached"
  63#define REVISION        "4.0"
  64#define MSPEC_BASENAME  "mspec"
  65
  66/*
  67 * Page types allocated by the device.
  68 */
  69enum mspec_page_type {
  70        MSPEC_FETCHOP = 1,
  71        MSPEC_CACHED,
  72        MSPEC_UNCACHED
  73};
  74
  75#ifdef CONFIG_SGI_SN
  76static int is_sn2;
  77#else
  78#define is_sn2          0
  79#endif
  80
  81/*
  82 * One of these structures is allocated when an mspec region is mmaped. The
  83 * structure is pointed to by the vma->vm_private_data field in the vma struct.
  84 * This structure is used to record the addresses of the mspec pages.
  85 * This structure is shared by all vma's that are split off from the
  86 * original vma when split_vma()'s are done.
  87 *
  88 * The refcnt is incremented atomically because mm->mmap_sem does not
  89 * protect in fork case where multiple tasks share the vma_data.
  90 */
  91struct vma_data {
  92        atomic_t refcnt;        /* Number of vmas sharing the data. */
  93        spinlock_t lock;        /* Serialize access to this structure. */
  94        int count;              /* Number of pages allocated. */
  95        enum mspec_page_type type; /* Type of pages allocated. */
  96        int flags;              /* See VMD_xxx below. */
  97        unsigned long vm_start; /* Original (unsplit) base. */
  98        unsigned long vm_end;   /* Original (unsplit) end. */
  99        unsigned long maddr[0]; /* Array of MSPEC addresses. */
 100};
 101
 102#define VMD_VMALLOCED 0x1       /* vmalloc'd rather than kmalloc'd */
 103
 104/* used on shub2 to clear FOP cache in the HUB */
 105static unsigned long scratch_page[MAX_NUMNODES];
 106#define SH2_AMO_CACHE_ENTRIES   4
 107
 108static inline int
 109mspec_zero_block(unsigned long addr, int len)
 110{
 111        int status;
 112
 113        if (is_sn2) {
 114                if (is_shub2()) {
 115                        int nid;
 116                        void *p;
 117                        int i;
 118
 119                        nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 120                        p = (void *)TO_AMO(scratch_page[nid]);
 121
 122                        for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 123                                FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 124                                p += FETCHOP_VAR_SIZE;
 125                        }
 126                }
 127
 128                status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 129                                  BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 130        } else {
 131                memset((char *) addr, 0, len);
 132                status = 0;
 133        }
 134        return status;
 135}
 136
 137/*
 138 * mspec_open
 139 *
 140 * Called when a device mapping is created by a means other than mmap
 141 * (via fork, munmap, etc.).  Increments the reference count on the
 142 * underlying mspec data so it is not freed prematurely.
 143 */
 144static void
 145mspec_open(struct vm_area_struct *vma)
 146{
 147        struct vma_data *vdata;
 148
 149        vdata = vma->vm_private_data;
 150        atomic_inc(&vdata->refcnt);
 151}
 152
 153/*
 154 * mspec_close
 155 *
 156 * Called when unmapping a device mapping. Frees all mspec pages
 157 * belonging to all the vma's sharing this vma_data structure.
 158 */
 159static void
 160mspec_close(struct vm_area_struct *vma)
 161{
 162        struct vma_data *vdata;
 163        int index, last_index;
 164        unsigned long my_page;
 165
 166        vdata = vma->vm_private_data;
 167
 168        if (!atomic_dec_and_test(&vdata->refcnt))
 169                return;
 170
 171        last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
 172        for (index = 0; index < last_index; index++) {
 173                if (vdata->maddr[index] == 0)
 174                        continue;
 175                /*
 176                 * Clear the page before sticking it back
 177                 * into the pool.
 178                 */
 179                my_page = vdata->maddr[index];
 180                vdata->maddr[index] = 0;
 181                if (!mspec_zero_block(my_page, PAGE_SIZE))
 182                        uncached_free_page(my_page, 1);
 183                else
 184                        printk(KERN_WARNING "mspec_close(): "
 185                               "failed to zero page %ld\n", my_page);
 186        }
 187
 188        if (vdata->flags & VMD_VMALLOCED)
 189                vfree(vdata);
 190        else
 191                kfree(vdata);
 192}
 193
 194/*
 195 * mspec_fault
 196 *
 197 * Creates a mspec page and maps it to user space.
 198 */
 199static int
 200mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 201{
 202        unsigned long paddr, maddr;
 203        unsigned long pfn;
 204        pgoff_t index = vmf->pgoff;
 205        struct vma_data *vdata = vma->vm_private_data;
 206
 207        maddr = (volatile unsigned long) vdata->maddr[index];
 208        if (maddr == 0) {
 209                maddr = uncached_alloc_page(numa_node_id(), 1);
 210                if (maddr == 0)
 211                        return VM_FAULT_OOM;
 212
 213                spin_lock(&vdata->lock);
 214                if (vdata->maddr[index] == 0) {
 215                        vdata->count++;
 216                        vdata->maddr[index] = maddr;
 217                } else {
 218                        uncached_free_page(maddr, 1);
 219                        maddr = vdata->maddr[index];
 220                }
 221                spin_unlock(&vdata->lock);
 222        }
 223
 224        if (vdata->type == MSPEC_FETCHOP)
 225                paddr = TO_AMO(maddr);
 226        else
 227                paddr = maddr & ~__IA64_UNCACHED_OFFSET;
 228
 229        pfn = paddr >> PAGE_SHIFT;
 230
 231        /*
 232         * vm_insert_pfn can fail with -EBUSY, but in that case it will
 233         * be because another thread has installed the pte first, so it
 234         * is no problem.
 235         */
 236        vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn);
 237
 238        return VM_FAULT_NOPAGE;
 239}
 240
 241static const struct vm_operations_struct mspec_vm_ops = {
 242        .open = mspec_open,
 243        .close = mspec_close,
 244        .fault = mspec_fault,
 245};
 246
 247/*
 248 * mspec_mmap
 249 *
 250 * Called when mmapping the device.  Initializes the vma with a fault handler
 251 * and private data structure necessary to allocate, track, and free the
 252 * underlying pages.
 253 */
 254static int
 255mspec_mmap(struct file *file, struct vm_area_struct *vma,
 256                                        enum mspec_page_type type)
 257{
 258        struct vma_data *vdata;
 259        int pages, vdata_size, flags = 0;
 260
 261        if (vma->vm_pgoff != 0)
 262                return -EINVAL;
 263
 264        if ((vma->vm_flags & VM_SHARED) == 0)
 265                return -EINVAL;
 266
 267        if ((vma->vm_flags & VM_WRITE) == 0)
 268                return -EPERM;
 269
 270        pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 271        vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 272        if (vdata_size <= PAGE_SIZE)
 273                vdata = kzalloc(vdata_size, GFP_KERNEL);
 274        else {
 275                vdata = vzalloc(vdata_size);
 276                flags = VMD_VMALLOCED;
 277        }
 278        if (!vdata)
 279                return -ENOMEM;
 280
 281        vdata->vm_start = vma->vm_start;
 282        vdata->vm_end = vma->vm_end;
 283        vdata->flags = flags;
 284        vdata->type = type;
 285        spin_lock_init(&vdata->lock);
 286        atomic_set(&vdata->refcnt, 1);
 287        vma->vm_private_data = vdata;
 288
 289        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
 290        if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 291                vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 292        vma->vm_ops = &mspec_vm_ops;
 293
 294        return 0;
 295}
 296
 297static int
 298fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 299{
 300        return mspec_mmap(file, vma, MSPEC_FETCHOP);
 301}
 302
 303static int
 304cached_mmap(struct file *file, struct vm_area_struct *vma)
 305{
 306        return mspec_mmap(file, vma, MSPEC_CACHED);
 307}
 308
 309static int
 310uncached_mmap(struct file *file, struct vm_area_struct *vma)
 311{
 312        return mspec_mmap(file, vma, MSPEC_UNCACHED);
 313}
 314
 315static const struct file_operations fetchop_fops = {
 316        .owner = THIS_MODULE,
 317        .mmap = fetchop_mmap,
 318        .llseek = noop_llseek,
 319};
 320
 321static struct miscdevice fetchop_miscdev = {
 322        .minor = MISC_DYNAMIC_MINOR,
 323        .name = "sgi_fetchop",
 324        .fops = &fetchop_fops
 325};
 326
 327static const struct file_operations cached_fops = {
 328        .owner = THIS_MODULE,
 329        .mmap = cached_mmap,
 330        .llseek = noop_llseek,
 331};
 332
 333static struct miscdevice cached_miscdev = {
 334        .minor = MISC_DYNAMIC_MINOR,
 335        .name = "mspec_cached",
 336        .fops = &cached_fops
 337};
 338
 339static const struct file_operations uncached_fops = {
 340        .owner = THIS_MODULE,
 341        .mmap = uncached_mmap,
 342        .llseek = noop_llseek,
 343};
 344
 345static struct miscdevice uncached_miscdev = {
 346        .minor = MISC_DYNAMIC_MINOR,
 347        .name = "mspec_uncached",
 348        .fops = &uncached_fops
 349};
 350
 351/*
 352 * mspec_init
 353 *
 354 * Called at boot time to initialize the mspec facility.
 355 */
 356static int __init
 357mspec_init(void)
 358{
 359        int ret;
 360        int nid;
 361
 362        /*
 363         * The fetchop device only works on SN2 hardware, uncached and cached
 364         * memory drivers should both be valid on all ia64 hardware
 365         */
 366#ifdef CONFIG_SGI_SN
 367        if (ia64_platform_is("sn2")) {
 368                is_sn2 = 1;
 369                if (is_shub2()) {
 370                        ret = -ENOMEM;
 371                        for_each_node_state(nid, N_ONLINE) {
 372                                int actual_nid;
 373                                int nasid;
 374                                unsigned long phys;
 375
 376                                scratch_page[nid] = uncached_alloc_page(nid, 1);
 377                                if (scratch_page[nid] == 0)
 378                                        goto free_scratch_pages;
 379                                phys = __pa(scratch_page[nid]);
 380                                nasid = get_node_number(phys);
 381                                actual_nid = nasid_to_cnodeid(nasid);
 382                                if (actual_nid != nid)
 383                                        goto free_scratch_pages;
 384                        }
 385                }
 386
 387                ret = misc_register(&fetchop_miscdev);
 388                if (ret) {
 389                        printk(KERN_ERR
 390                               "%s: failed to register device %i\n",
 391                               FETCHOP_ID, ret);
 392                        goto free_scratch_pages;
 393                }
 394        }
 395#endif
 396        ret = misc_register(&cached_miscdev);
 397        if (ret) {
 398                printk(KERN_ERR "%s: failed to register device %i\n",
 399                       CACHED_ID, ret);
 400                if (is_sn2)
 401                        misc_deregister(&fetchop_miscdev);
 402                goto free_scratch_pages;
 403        }
 404        ret = misc_register(&uncached_miscdev);
 405        if (ret) {
 406                printk(KERN_ERR "%s: failed to register device %i\n",
 407                       UNCACHED_ID, ret);
 408                misc_deregister(&cached_miscdev);
 409                if (is_sn2)
 410                        misc_deregister(&fetchop_miscdev);
 411                goto free_scratch_pages;
 412        }
 413
 414        printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 415               MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 416               CACHED_ID, UNCACHED_ID);
 417
 418        return 0;
 419
 420 free_scratch_pages:
 421        for_each_node(nid) {
 422                if (scratch_page[nid] != 0)
 423                        uncached_free_page(scratch_page[nid], 1);
 424        }
 425        return ret;
 426}
 427
 428static void __exit
 429mspec_exit(void)
 430{
 431        int nid;
 432
 433        misc_deregister(&uncached_miscdev);
 434        misc_deregister(&cached_miscdev);
 435        if (is_sn2) {
 436                misc_deregister(&fetchop_miscdev);
 437
 438                for_each_node(nid) {
 439                        if (scratch_page[nid] != 0)
 440                                uncached_free_page(scratch_page[nid], 1);
 441                }
 442        }
 443}
 444
 445module_init(mspec_init);
 446module_exit(mspec_exit);
 447
 448MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 449MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 450MODULE_LICENSE("GPL");
 451
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.