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"); 451