drivers/char/mspec.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2001-2006 Silicon Graphics, Inc.  All rights
   4  * reserved.
   5  */
   6
   7 /*
   8  * SN Platform Special Memory (mspec) Support
   9  *
  10  * This driver exports the SN special memory (mspec) facility to user
  11  * processes.
  12  * There are three types of memory made available thru this driver:
  13  * fetchops, uncached and cached.
  14  *
  15  * Fetchops are atomic memory operations that are implemented in the
  16  * memory controller on SGI SN hardware.
  17  *
  18  * Uncached are used for memory write combining feature of the ia64
  19  * cpu.
  20  *
  21  * Cached are used for areas of memory that are used as cached addresses
  22  * on our partition and used as uncached addresses from other partitions.
  23  * Due to a design constraint of the SN2 Shub, you can not have processors
  24  * on the same FSB perform both a cached and uncached reference to the
  25  * same cache line.  These special memory cached regions prevent the
  26  * kernel from ever dropping in a TLB entry and therefore prevent the
  27  * processor from ever speculating a cache line from this page.
  28  */
  29
  30 #include <linux/types.h>
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/init.h>
  34 #include <linux/errno.h>
  35 #include <linux/miscdevice.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/mm.h>
  38 #include <linux/fs.h>
  39 #include <linux/vmalloc.h>
  40 #include <linux/string.h>
  41 #include <linux/slab.h>
  42 #include <linux/numa.h>
  43 #include <linux/refcount.h>
  44 #include <asm/page.h>
  45 #include <asm/pgtable.h>
  46 #include <linux/atomic.h>
  47 #include <asm/tlbflush.h>
  48 #include <asm/uncached.h>
  49 #include <asm/sn/addrs.h>
  50 #include <asm/sn/arch.h>
  51 #include <asm/sn/mspec.h>
  52 #include <asm/sn/sn_cpuid.h>
  53 #include <asm/sn/io.h>
  54 #include <asm/sn/bte.h>
  55 #include <asm/sn/shubio.h>
  56
  57
  58 #define FETCHOP_ID      "SGI Fetchop,"
  59 #define CACHED_ID       "Cached,"
  60 #define UNCACHED_ID     "Uncached"
  61 #define REVISION        "4.0"
  62 #define MSPEC_BASENAME  "mspec"
  63
  64 /*
  65  * Page types allocated by the device.
  66  */
  67 enum mspec_page_type {
  68         MSPEC_FETCHOP = 1,
  69         MSPEC_CACHED,
  70         MSPEC_UNCACHED
  71 };
  72
  73 #ifdef CONFIG_SGI_SN
  74 static int is_sn2;
  75 #else
  76 #define is_sn2          0
  77 #endif
  78
  79 /*
  80  * One of these structures is allocated when an mspec region is mmaped. The
  81  * structure is pointed to by the vma->vm_private_data field in the vma struct.
  82  * This structure is used to record the addresses of the mspec pages.
  83  * This structure is shared by all vma's that are split off from the
  84  * original vma when split_vma()'s are done.
  85  *
  86  * The refcnt is incremented atomically because mm->mmap_sem does not
  87  * protect in fork case where multiple tasks share the vma_data.
  88  */
  89 struct vma_data {
  90         refcount_t refcnt;      /* Number of vmas sharing the data. */
  91         spinlock_t lock;        /* Serialize access to this structure. */
  92         int count;              /* Number of pages allocated. */
  93         enum mspec_page_type type; /* Type of pages allocated. */
  94         unsigned long vm_start; /* Original (unsplit) base. */
  95         unsigned long vm_end;   /* Original (unsplit) end. */
  96         unsigned long maddr[0]; /* Array of MSPEC addresses. */
  97 };
  98
  99 /* used on shub2 to clear FOP cache in the HUB */
 100 static unsigned long scratch_page[MAX_NUMNODES];
 101 #define SH2_AMO_CACHE_ENTRIES   4
 102
 103 static inline int
 104 mspec_zero_block(unsigned long addr, int len)
 105 {
 106         int status;
 107
 108         if (is_sn2) {
 109                 if (is_shub2()) {
 110                         int nid;
 111                         void *p;
 112                         int i;
 113
 114                         nid = nasid_to_cnodeid(get_node_number(__pa(addr)));
 115                         p = (void *)TO_AMO(scratch_page[nid]);
 116
 117                         for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) {
 118                                 FETCHOP_LOAD_OP(p, FETCHOP_LOAD);
 119                                 p += FETCHOP_VAR_SIZE;
 120                         }
 121                 }
 122
 123                 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len,
 124                                   BTE_WACQUIRE | BTE_ZERO_FILL, NULL);
 125         } else {
 126                 memset((char *) addr, 0, len);
 127                 status = 0;
 128         }
 129         return status;
 130 }
 131
 132 /*
 133  * mspec_open
 134  *
 135  * Called when a device mapping is created by a means other than mmap
 136  * (via fork, munmap, etc.).  Increments the reference count on the
 137  * underlying mspec data so it is not freed prematurely.
 138  */
 139 static void
 140 mspec_open(struct vm_area_struct *vma)
 141 {
 142         struct vma_data *vdata;
 143
 144         vdata = vma->vm_private_data;
 145         refcount_inc(&vdata->refcnt);
 146 }
 147
 148 /*
 149  * mspec_close
 150  *
 151  * Called when unmapping a device mapping. Frees all mspec pages
 152  * belonging to all the vma's sharing this vma_data structure.
 153  */
 154 static void
 155 mspec_close(struct vm_area_struct *vma)
 156 {
 157         struct vma_data *vdata;
 158         int index, last_index;
 159         unsigned long my_page;
 160
 161         vdata = vma->vm_private_data;
 162
 163         if (!refcount_dec_and_test(&vdata->refcnt))
 164                 return;
 165
 166         last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
 167         for (index = 0; index < last_index; index++) {
 168                 if (vdata->maddr[index] == 0)
 169                         continue;
 170                 /*
 171                  * Clear the page before sticking it back
 172                  * into the pool.
 173                  */
 174                 my_page = vdata->maddr[index];
 175                 vdata->maddr[index] = 0;
 176                 if (!mspec_zero_block(my_page, PAGE_SIZE))
 177                         uncached_free_page(my_page, 1);
 178                 else
 179                         printk(KERN_WARNING "mspec_close(): "
 180                                "failed to zero page %ld\n", my_page);
 181         }
 182
 183         kvfree(vdata);
 184 }
 185
 186 /*
 187  * mspec_fault
 188  *
 189  * Creates a mspec page and maps it to user space.
 190  */
 191 static vm_fault_t
 192 mspec_fault(struct vm_fault *vmf)
 193 {
 194         unsigned long paddr, maddr;
 195         unsigned long pfn;
 196         pgoff_t index = vmf->pgoff;
 197         struct vma_data *vdata = vmf->vma->vm_private_data;
 198
 199         maddr = (volatile unsigned long) vdata->maddr[index];
 200         if (maddr == 0) {
 201                 maddr = uncached_alloc_page(numa_node_id(), 1);
 202                 if (maddr == 0)
 203                         return VM_FAULT_OOM;
 204
 205                 spin_lock(&vdata->lock);
 206                 if (vdata->maddr[index] == 0) {
 207                         vdata->count++;
 208                         vdata->maddr[index] = maddr;
 209                 } else {
 210                         uncached_free_page(maddr, 1);
 211                         maddr = vdata->maddr[index];
 212                 }
 213                 spin_unlock(&vdata->lock);
 214         }
 215
 216         if (vdata->type == MSPEC_FETCHOP)
 217                 paddr = TO_AMO(maddr);
 218         else
 219                 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
 220
 221         pfn = paddr >> PAGE_SHIFT;
 222
 223         return vmf_insert_pfn(vmf->vma, vmf->address, pfn);
 224 }
 225
 226 static const struct vm_operations_struct mspec_vm_ops = {
 227         .open = mspec_open,
 228         .close = mspec_close,
 229         .fault = mspec_fault,
 230 };
 231
 232 /*
 233  * mspec_mmap
 234  *
 235  * Called when mmapping the device.  Initializes the vma with a fault handler
 236  * and private data structure necessary to allocate, track, and free the
 237  * underlying pages.
 238  */
 239 static int
 240 mspec_mmap(struct file *file, struct vm_area_struct *vma,
 241                                         enum mspec_page_type type)
 242 {
 243         struct vma_data *vdata;
 244         int pages, vdata_size;
 245
 246         if (vma->vm_pgoff != 0)
 247                 return -EINVAL;
 248
 249         if ((vma->vm_flags & VM_SHARED) == 0)
 250                 return -EINVAL;
 251
 252         if ((vma->vm_flags & VM_WRITE) == 0)
 253                 return -EPERM;
 254
 255         pages = vma_pages(vma);
 256         vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
 257         if (vdata_size <= PAGE_SIZE)
 258                 vdata = kzalloc(vdata_size, GFP_KERNEL);
 259         else
 260                 vdata = vzalloc(vdata_size);
 261         if (!vdata)
 262                 return -ENOMEM;
 263
 264         vdata->vm_start = vma->vm_start;
 265         vdata->vm_end = vma->vm_end;
 266         vdata->type = type;
 267         spin_lock_init(&vdata->lock);
 268         refcount_set(&vdata->refcnt, 1);
 269         vma->vm_private_data = vdata;
 270
 271         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
 272         if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
 273                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
 274         vma->vm_ops = &mspec_vm_ops;
 275
 276         return 0;
 277 }
 278
 279 static int
 280 fetchop_mmap(struct file *file, struct vm_area_struct *vma)
 281 {
 282         return mspec_mmap(file, vma, MSPEC_FETCHOP);
 283 }
 284
 285 static int
 286 cached_mmap(struct file *file, struct vm_area_struct *vma)
 287 {
 288         return mspec_mmap(file, vma, MSPEC_CACHED);
 289 }
 290
 291 static int
 292 uncached_mmap(struct file *file, struct vm_area_struct *vma)
 293 {
 294         return mspec_mmap(file, vma, MSPEC_UNCACHED);
 295 }
 296
 297 static const struct file_operations fetchop_fops = {
 298         .owner = THIS_MODULE,
 299         .mmap = fetchop_mmap,
 300         .llseek = noop_llseek,
 301 };
 302
 303 static struct miscdevice fetchop_miscdev = {
 304         .minor = MISC_DYNAMIC_MINOR,
 305         .name = "sgi_fetchop",
 306         .fops = &fetchop_fops
 307 };
 308
 309 static const struct file_operations cached_fops = {
 310         .owner = THIS_MODULE,
 311         .mmap = cached_mmap,
 312         .llseek = noop_llseek,
 313 };
 314
 315 static struct miscdevice cached_miscdev = {
 316         .minor = MISC_DYNAMIC_MINOR,
 317         .name = "mspec_cached",
 318         .fops = &cached_fops
 319 };
 320
 321 static const struct file_operations uncached_fops = {
 322         .owner = THIS_MODULE,
 323         .mmap = uncached_mmap,
 324         .llseek = noop_llseek,
 325 };
 326
 327 static struct miscdevice uncached_miscdev = {
 328         .minor = MISC_DYNAMIC_MINOR,
 329         .name = "mspec_uncached",
 330         .fops = &uncached_fops
 331 };
 332
 333 /*
 334  * mspec_init
 335  *
 336  * Called at boot time to initialize the mspec facility.
 337  */
 338 static int __init
 339 mspec_init(void)
 340 {
 341         int ret;
 342         int nid;
 343
 344         /*
 345          * The fetchop device only works on SN2 hardware, uncached and cached
 346          * memory drivers should both be valid on all ia64 hardware
 347          */
 348 #ifdef CONFIG_SGI_SN
 349         if (ia64_platform_is("sn2")) {
 350                 is_sn2 = 1;
 351                 if (is_shub2()) {
 352                         ret = -ENOMEM;
 353                         for_each_node_state(nid, N_ONLINE) {
 354                                 int actual_nid;
 355                                 int nasid;
 356                                 unsigned long phys;
 357
 358                                 scratch_page[nid] = uncached_alloc_page(nid, 1);
 359                                 if (scratch_page[nid] == 0)
 360                                         goto free_scratch_pages;
 361                                 phys = __pa(scratch_page[nid]);
 362                                 nasid = get_node_number(phys);
 363                                 actual_nid = nasid_to_cnodeid(nasid);
 364                                 if (actual_nid != nid)
 365                                         goto free_scratch_pages;
 366                         }
 367                 }
 368
 369                 ret = misc_register(&fetchop_miscdev);
 370                 if (ret) {
 371                         printk(KERN_ERR
 372                                "%s: failed to register device %i\n",
 373                                FETCHOP_ID, ret);
 374                         goto free_scratch_pages;
 375                 }
 376         }
 377 #endif
 378         ret = misc_register(&cached_miscdev);
 379         if (ret) {
 380                 printk(KERN_ERR "%s: failed to register device %i\n",
 381                        CACHED_ID, ret);
 382                 if (is_sn2)
 383                         misc_deregister(&fetchop_miscdev);
 384                 goto free_scratch_pages;
 385         }
 386         ret = misc_register(&uncached_miscdev);
 387         if (ret) {
 388                 printk(KERN_ERR "%s: failed to register device %i\n",
 389                        UNCACHED_ID, ret);
 390                 misc_deregister(&cached_miscdev);
 391                 if (is_sn2)
 392                         misc_deregister(&fetchop_miscdev);
 393                 goto free_scratch_pages;
 394         }
 395
 396         printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
 397                MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
 398                CACHED_ID, UNCACHED_ID);
 399
 400         return 0;
 401
 402  free_scratch_pages:
 403         for_each_node(nid) {
 404                 if (scratch_page[nid] != 0)
 405                         uncached_free_page(scratch_page[nid], 1);
 406         }
 407         return ret;
 408 }
 409
 410 static void __exit
 411 mspec_exit(void)
 412 {
 413         int nid;
 414
 415         misc_deregister(&uncached_miscdev);
 416         misc_deregister(&cached_miscdev);
 417         if (is_sn2) {
 418                 misc_deregister(&fetchop_miscdev);
 419
 420                 for_each_node(nid) {
 421                         if (scratch_page[nid] != 0)
 422                                 uncached_free_page(scratch_page[nid], 1);
 423                 }
 424         }
 425 }
 426
 427 module_init(mspec_init);
 428 module_exit(mspec_exit);
 429
 430 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
 431 MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
 432 MODULE_LICENSE("GPL");