drivers/char/mspec.c

   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  */
  69 enum mspec_page_type {
  70         MSPEC_FETCHOP = 1,
  71         MSPEC_CACHED,
  72         MSPEC_UNCACHED
  73 };
  74
  75 #ifdef CONFIG_SGI_SN
  76 static 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  */
  91 struct 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 */
 105 static unsigned long scratch_page[MAX_NUMNODES];
 106 #define SH2_AMO_CACHE_ENTRIES   4
 107
 108 static inline int
 109 mspec_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  */
 144 static void
 145 mspec_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  */
 159 static void
 160 mspec_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  */
 199 static int
 200 mspec_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
 241 static 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  */
 254 static int
 255 mspec_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_pages(vma);
 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
 297 static int
 298 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 299 {
 300         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 301 }
 302
 303 static int
 304 cached_mmap(struct file *file, struct vm_area_struct *vma)
 305 {
 306         return mspec_mmap(file, vma, MSPEC_CACHED);
 307 }
 308
 309 static int
 310 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 311 {
 312         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 313 }
 314
 315 static const struct file_operations fetchop_fops = {
 316         .owner = THIS_MODULE,
 317         .mmap = fetchop_mmap,
 318         .llseek = noop_llseek,
 319 };
 320
 321 static struct miscdevice fetchop_miscdev = {
 322         .minor = MISC_DYNAMIC_MINOR,
 323         .name = "sgi_fetchop",
 324         .fops = &fetchop_fops
 325 };
 326
 327 static const struct file_operations cached_fops = {
 328         .owner = THIS_MODULE,
 329         .mmap = cached_mmap,
 330         .llseek = noop_llseek,
 331 };
 332
 333 static struct miscdevice cached_miscdev = {
 334         .minor = MISC_DYNAMIC_MINOR,
 335         .name = "mspec_cached",
 336         .fops = &cached_fops
 337 };
 338
 339 static const struct file_operations uncached_fops = {
 340         .owner = THIS_MODULE,
 341         .mmap = uncached_mmap,
 342         .llseek = noop_llseek,
 343 };
 344
 345 static 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  */
 356 static int __init
 357 mspec_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
 428 static void __exit
 429 mspec_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
 445 module_init(mspec_init);
 446 module_exit(mspec_exit);
 447
 448 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 449 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 450 MODULE_LICENSE("GPL");