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/system.h> 48 #include <asm/pgtable.h> 49 #include <linux/atomic.h> 50 #include <asm/tlbflush.h> 51 #include <asm/uncached.h> 52 #include <asm/sn/addrs.h> 53 #include <asm/sn/arch.h> 54 #include <asm/sn/mspec.h> 55 #include <asm/sn/sn_cpuid.h> 56 #include <asm/sn/io.h> 57 #include <asm/sn/bte.h> 58 #include <asm/sn/shubio.h> 59 60 61 #define FETCHOP_ID "SGI Fetchop," 62 #define CACHED_ID "Cached," 63 #define UNCACHED_ID "Uncached" 64 #define REVISION "4.0" 65 #define MSPEC_BASENAME "mspec" 66 67 /* 68 * Page types allocated by the device. 69 */ 70 enum mspec_page_type { 71 MSPEC_FETCHOP = 1, 72 MSPEC_CACHED, 73 MSPEC_UNCACHED 74 }; 75 76 #ifdef CONFIG_SGI_SN 77 static int is_sn2; 78 #else 79 #define is_sn2 0 80 #endif 81 82 /* 83 * One of these structures is allocated when an mspec region is mmaped. The 84 * structure is pointed to by the vma->vm_private_data field in the vma struct. 85 * This structure is used to record the addresses of the mspec pages. 86 * This structure is shared by all vma's that are split off from the 87 * original vma when split_vma()'s are done. 88 * 89 * The refcnt is incremented atomically because mm->mmap_sem does not 90 * protect in fork case where multiple tasks share the vma_data. 91 */ 92 struct vma_data { 93 atomic_t refcnt; /* Number of vmas sharing the data. */ 94 spinlock_t lock; /* Serialize access to this structure. */ 95 int count; /* Number of pages allocated. */ 96 enum mspec_page_type type; /* Type of pages allocated. */ 97 int flags; /* See VMD_xxx below. */ 98 unsigned long vm_start; /* Original (unsplit) base. */ 99 unsigned long vm_end; /* Original (unsplit) end. */ 100 unsigned long maddr[0]; /* Array of MSPEC addresses. */ 101 }; 102 103 #define VMD_VMALLOCED 0x1 /* vmalloc'd rather than kmalloc'd */ 104 105 /* used on shub2 to clear FOP cache in the HUB */ 106 static unsigned long scratch_page[MAX_NUMNODES]; 107 #define SH2_AMO_CACHE_ENTRIES 4 108 109 static inline int 110 mspec_zero_block(unsigned long addr, int len) 111 { 112 int status; 113 114 if (is_sn2) { 115 if (is_shub2()) { 116 int nid; 117 void *p; 118 int i; 119 120 nid = nasid_to_cnodeid(get_node_number(__pa(addr))); 121 p = (void *)TO_AMO(scratch_page[nid]); 122 123 for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) { 124 FETCHOP_LOAD_OP(p, FETCHOP_LOAD); 125 p += FETCHOP_VAR_SIZE; 126 } 127 } 128 129 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len, 130 BTE_WACQUIRE | BTE_ZERO_FILL, NULL); 131 } else { 132 memset((char *) addr, 0, len); 133 status = 0; 134 } 135 return status; 136 } 137 138 /* 139 * mspec_open 140 * 141 * Called when a device mapping is created by a means other than mmap 142 * (via fork, munmap, etc.). Increments the reference count on the 143 * underlying mspec data so it is not freed prematurely. 144 */ 145 static void 146 mspec_open(struct vm_area_struct *vma) 147 { 148 struct vma_data *vdata; 149 150 vdata = vma->vm_private_data; 151 atomic_inc(&vdata->refcnt); 152 } 153 154 /* 155 * mspec_close 156 * 157 * Called when unmapping a device mapping. Frees all mspec pages 158 * belonging to all the vma's sharing this vma_data structure. 159 */ 160 static void 161 mspec_close(struct vm_area_struct *vma) 162 { 163 struct vma_data *vdata; 164 int index, last_index; 165 unsigned long my_page; 166 167 vdata = vma->vm_private_data; 168 169 if (!atomic_dec_and_test(&vdata->refcnt)) 170 return; 171 172 last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT; 173 for (index = 0; index < last_index; index++) { 174 if (vdata->maddr[index] == 0) 175 continue; 176 /* 177 * Clear the page before sticking it back 178 * into the pool. 179 */ 180 my_page = vdata->maddr[index]; 181 vdata->maddr[index] = 0; 182 if (!mspec_zero_block(my_page, PAGE_SIZE)) 183 uncached_free_page(my_page, 1); 184 else 185 printk(KERN_WARNING "mspec_close(): " 186 "failed to zero page %ld\n", my_page); 187 } 188 189 if (vdata->flags & VMD_VMALLOCED) 190 vfree(vdata); 191 else 192 kfree(vdata); 193 } 194 195 /* 196 * mspec_fault 197 * 198 * Creates a mspec page and maps it to user space. 199 */ 200 static int 201 mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 202 { 203 unsigned long paddr, maddr; 204 unsigned long pfn; 205 pgoff_t index = vmf->pgoff; 206 struct vma_data *vdata = vma->vm_private_data; 207 208 maddr = (volatile unsigned long) vdata->maddr[index]; 209 if (maddr == 0) { 210 maddr = uncached_alloc_page(numa_node_id(), 1); 211 if (maddr == 0) 212 return VM_FAULT_OOM; 213 214 spin_lock(&vdata->lock); 215 if (vdata->maddr[index] == 0) { 216 vdata->count++; 217 vdata->maddr[index] = maddr; 218 } else { 219 uncached_free_page(maddr, 1); 220 maddr = vdata->maddr[index]; 221 } 222 spin_unlock(&vdata->lock); 223 } 224 225 if (vdata->type == MSPEC_FETCHOP) 226 paddr = TO_AMO(maddr); 227 else 228 paddr = maddr & ~__IA64_UNCACHED_OFFSET; 229 230 pfn = paddr >> PAGE_SHIFT; 231 232 /* 233 * vm_insert_pfn can fail with -EBUSY, but in that case it will 234 * be because another thread has installed the pte first, so it 235 * is no problem. 236 */ 237 vm_insert_pfn(vma, (unsigned long)vmf->virtual_address, pfn); 238 239 return VM_FAULT_NOPAGE; 240 } 241 242 static const struct vm_operations_struct mspec_vm_ops = { 243 .open = mspec_open, 244 .close = mspec_close, 245 .fault = mspec_fault, 246 }; 247 248 /* 249 * mspec_mmap 250 * 251 * Called when mmapping the device. Initializes the vma with a fault handler 252 * and private data structure necessary to allocate, track, and free the 253 * underlying pages. 254 */ 255 static int 256 mspec_mmap(struct file *file, struct vm_area_struct *vma, 257 enum mspec_page_type type) 258 { 259 struct vma_data *vdata; 260 int pages, vdata_size, flags = 0; 261 262 if (vma->vm_pgoff != 0) 263 return -EINVAL; 264 265 if ((vma->vm_flags & VM_SHARED) == 0) 266 return -EINVAL; 267 268 if ((vma->vm_flags & VM_WRITE) == 0) 269 return -EPERM; 270 271 pages = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 272 vdata_size = sizeof(struct vma_data) + pages * sizeof(long); 273 if (vdata_size <= PAGE_SIZE) 274 vdata = kzalloc(vdata_size, GFP_KERNEL); 275 else { 276 vdata = vzalloc(vdata_size); 277 flags = VMD_VMALLOCED; 278 } 279 if (!vdata) 280 return -ENOMEM; 281 282 vdata->vm_start = vma->vm_start; 283 vdata->vm_end = vma->vm_end; 284 vdata->flags = flags; 285 vdata->type = type; 286 spin_lock_init(&vdata->lock); 287 vdata->refcnt = ATOMIC_INIT(1); 288 vma->vm_private_data = vdata; 289 290 vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND); 291 if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED) 292 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 293 vma->vm_ops = &mspec_vm_ops; 294 295 return 0; 296 } 297 298 static int 299 fetchop_mmap(struct file *file, struct vm_area_struct *vma) 300 { 301 return mspec_mmap(file, vma, MSPEC_FETCHOP); 302 } 303 304 static int 305 cached_mmap(struct file *file, struct vm_area_struct *vma) 306 { 307 return mspec_mmap(file, vma, MSPEC_CACHED); 308 } 309 310 static int 311 uncached_mmap(struct file *file, struct vm_area_struct *vma) 312 { 313 return mspec_mmap(file, vma, MSPEC_UNCACHED); 314 } 315 316 static const struct file_operations fetchop_fops = { 317 .owner = THIS_MODULE, 318 .mmap = fetchop_mmap, 319 .llseek = noop_llseek, 320 }; 321 322 static struct miscdevice fetchop_miscdev = { 323 .minor = MISC_DYNAMIC_MINOR, 324 .name = "sgi_fetchop", 325 .fops = &fetchop_fops 326 }; 327 328 static const struct file_operations cached_fops = { 329 .owner = THIS_MODULE, 330 .mmap = cached_mmap, 331 .llseek = noop_llseek, 332 }; 333 334 static struct miscdevice cached_miscdev = { 335 .minor = MISC_DYNAMIC_MINOR, 336 .name = "mspec_cached", 337 .fops = &cached_fops 338 }; 339 340 static const struct file_operations uncached_fops = { 341 .owner = THIS_MODULE, 342 .mmap = uncached_mmap, 343 .llseek = noop_llseek, 344 }; 345 346 static struct miscdevice uncached_miscdev = { 347 .minor = MISC_DYNAMIC_MINOR, 348 .name = "mspec_uncached", 349 .fops = &uncached_fops 350 }; 351 352 /* 353 * mspec_init 354 * 355 * Called at boot time to initialize the mspec facility. 356 */ 357 static int __init 358 mspec_init(void) 359 { 360 int ret; 361 int nid; 362 363 /* 364 * The fetchop device only works on SN2 hardware, uncached and cached 365 * memory drivers should both be valid on all ia64 hardware 366 */ 367 #ifdef CONFIG_SGI_SN 368 if (ia64_platform_is("sn2")) { 369 is_sn2 = 1; 370 if (is_shub2()) { 371 ret = -ENOMEM; 372 for_each_node_state(nid, N_ONLINE) { 373 int actual_nid; 374 int nasid; 375 unsigned long phys; 376 377 scratch_page[nid] = uncached_alloc_page(nid, 1); 378 if (scratch_page[nid] == 0) 379 goto free_scratch_pages; 380 phys = __pa(scratch_page[nid]); 381 nasid = get_node_number(phys); 382 actual_nid = nasid_to_cnodeid(nasid); 383 if (actual_nid != nid) 384 goto free_scratch_pages; 385 } 386 } 387 388 ret = misc_register(&fetchop_miscdev); 389 if (ret) { 390 printk(KERN_ERR 391 "%s: failed to register device %i\n", 392 FETCHOP_ID, ret); 393 goto free_scratch_pages; 394 } 395 } 396 #endif 397 ret = misc_register(&cached_miscdev); 398 if (ret) { 399 printk(KERN_ERR "%s: failed to register device %i\n", 400 CACHED_ID, ret); 401 if (is_sn2) 402 misc_deregister(&fetchop_miscdev); 403 goto free_scratch_pages; 404 } 405 ret = misc_register(&uncached_miscdev); 406 if (ret) { 407 printk(KERN_ERR "%s: failed to register device %i\n", 408 UNCACHED_ID, ret); 409 misc_deregister(&cached_miscdev); 410 if (is_sn2) 411 misc_deregister(&fetchop_miscdev); 412 goto free_scratch_pages; 413 } 414 415 printk(KERN_INFO "%s %s initialized devices: %s %s %s\n", 416 MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "", 417 CACHED_ID, UNCACHED_ID); 418 419 return 0; 420 421 free_scratch_pages: 422 for_each_node(nid) { 423 if (scratch_page[nid] != 0) 424 uncached_free_page(scratch_page[nid], 1); 425 } 426 return ret; 427 } 428 429 static void __exit 430 mspec_exit(void) 431 { 432 int nid; 433 434 misc_deregister(&uncached_miscdev); 435 misc_deregister(&cached_miscdev); 436 if (is_sn2) { 437 misc_deregister(&fetchop_miscdev); 438 439 for_each_node(nid) { 440 if (scratch_page[nid] != 0) 441 uncached_free_page(scratch_page[nid], 1); 442 } 443 } 444 } 445 446 module_init(mspec_init); 447 module_exit(mspec_exit); 448 449 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>"); 450 MODULE_DESCRIPTION("Driver for SGI SN special memory operations"); 451 MODULE_LICENSE("GPL"); 452