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 <linux/refcount.h> 47 #include <asm/page.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 refcount_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 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 /* used on shub2 to clear FOP cache in the HUB */ 103 static unsigned long scratch_page[MAX_NUMNODES]; 104 #define SH2_AMO_CACHE_ENTRIES 4 105 106 static inline int 107 mspec_zero_block(unsigned long addr, int len) 108 { 109 int status; 110 111 if (is_sn2) { 112 if (is_shub2()) { 113 int nid; 114 void *p; 115 int i; 116 117 nid = nasid_to_cnodeid(get_node_number(__pa(addr))); 118 p = (void *)TO_AMO(scratch_page[nid]); 119 120 for (i=0; i < SH2_AMO_CACHE_ENTRIES; i++) { 121 FETCHOP_LOAD_OP(p, FETCHOP_LOAD); 122 p += FETCHOP_VAR_SIZE; 123 } 124 } 125 126 status = bte_copy(0, addr & ~__IA64_UNCACHED_OFFSET, len, 127 BTE_WACQUIRE | BTE_ZERO_FILL, NULL); 128 } else { 129 memset((char *) addr, 0, len); 130 status = 0; 131 } 132 return status; 133 } 134 135 /* 136 * mspec_open 137 * 138 * Called when a device mapping is created by a means other than mmap 139 * (via fork, munmap, etc.). Increments the reference count on the 140 * underlying mspec data so it is not freed prematurely. 141 */ 142 static void 143 mspec_open(struct vm_area_struct *vma) 144 { 145 struct vma_data *vdata; 146 147 vdata = vma->vm_private_data; 148 refcount_inc(&vdata->refcnt); 149 } 150 151 /* 152 * mspec_close 153 * 154 * Called when unmapping a device mapping. Frees all mspec pages 155 * belonging to all the vma's sharing this vma_data structure. 156 */ 157 static void 158 mspec_close(struct vm_area_struct *vma) 159 { 160 struct vma_data *vdata; 161 int index, last_index; 162 unsigned long my_page; 163 164 vdata = vma->vm_private_data; 165 166 if (!refcount_dec_and_test(&vdata->refcnt)) 167 return; 168 169 last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT; 170 for (index = 0; index < last_index; index++) { 171 if (vdata->maddr[index] == 0) 172 continue; 173 /* 174 * Clear the page before sticking it back 175 * into the pool. 176 */ 177 my_page = vdata->maddr[index]; 178 vdata->maddr[index] = 0; 179 if (!mspec_zero_block(my_page, PAGE_SIZE)) 180 uncached_free_page(my_page, 1); 181 else 182 printk(KERN_WARNING "mspec_close(): " 183 "failed to zero page %ld\n", my_page); 184 } 185 186 kvfree(vdata); 187 } 188 189 /* 190 * mspec_fault 191 * 192 * Creates a mspec page and maps it to user space. 193 */ 194 static vm_fault_t 195 mspec_fault(struct vm_fault *vmf) 196 { 197 unsigned long paddr, maddr; 198 unsigned long pfn; 199 pgoff_t index = vmf->pgoff; 200 struct vma_data *vdata = vmf->vma->vm_private_data; 201 202 maddr = (volatile unsigned long) vdata->maddr[index]; 203 if (maddr == 0) { 204 maddr = uncached_alloc_page(numa_node_id(), 1); 205 if (maddr == 0) 206 return VM_FAULT_OOM; 207 208 spin_lock(&vdata->lock); 209 if (vdata->maddr[index] == 0) { 210 vdata->count++; 211 vdata->maddr[index] = maddr; 212 } else { 213 uncached_free_page(maddr, 1); 214 maddr = vdata->maddr[index]; 215 } 216 spin_unlock(&vdata->lock); 217 } 218 219 if (vdata->type == MSPEC_FETCHOP) 220 paddr = TO_AMO(maddr); 221 else 222 paddr = maddr & ~__IA64_UNCACHED_OFFSET; 223 224 pfn = paddr >> PAGE_SHIFT; 225 226 return vmf_insert_pfn(vmf->vma, vmf->address, pfn); 227 } 228 229 static const struct vm_operations_struct mspec_vm_ops = { 230 .open = mspec_open, 231 .close = mspec_close, 232 .fault = mspec_fault, 233 }; 234 235 /* 236 * mspec_mmap 237 * 238 * Called when mmapping the device. Initializes the vma with a fault handler 239 * and private data structure necessary to allocate, track, and free the 240 * underlying pages. 241 */ 242 static int 243 mspec_mmap(struct file *file, struct vm_area_struct *vma, 244 enum mspec_page_type type) 245 { 246 struct vma_data *vdata; 247 int pages, vdata_size; 248 249 if (vma->vm_pgoff != 0) 250 return -EINVAL; 251 252 if ((vma->vm_flags & VM_SHARED) == 0) 253 return -EINVAL; 254 255 if ((vma->vm_flags & VM_WRITE) == 0) 256 return -EPERM; 257 258 pages = vma_pages(vma); 259 vdata_size = sizeof(struct vma_data) + pages * sizeof(long); 260 if (vdata_size <= PAGE_SIZE) 261 vdata = kzalloc(vdata_size, GFP_KERNEL); 262 else 263 vdata = vzalloc(vdata_size); 264 if (!vdata) 265 return -ENOMEM; 266 267 vdata->vm_start = vma->vm_start; 268 vdata->vm_end = vma->vm_end; 269 vdata->type = type; 270 spin_lock_init(&vdata->lock); 271 refcount_set(&vdata->refcnt, 1); 272 vma->vm_private_data = vdata; 273 274 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 275 if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED) 276 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 277 vma->vm_ops = &mspec_vm_ops; 278 279 return 0; 280 } 281 282 static int 283 fetchop_mmap(struct file *file, struct vm_area_struct *vma) 284 { 285 return mspec_mmap(file, vma, MSPEC_FETCHOP); 286 } 287 288 static int 289 cached_mmap(struct file *file, struct vm_area_struct *vma) 290 { 291 return mspec_mmap(file, vma, MSPEC_CACHED); 292 } 293 294 static int 295 uncached_mmap(struct file *file, struct vm_area_struct *vma) 296 { 297 return mspec_mmap(file, vma, MSPEC_UNCACHED); 298 } 299 300 static const struct file_operations fetchop_fops = { 301 .owner = THIS_MODULE, 302 .mmap = fetchop_mmap, 303 .llseek = noop_llseek, 304 }; 305 306 static struct miscdevice fetchop_miscdev = { 307 .minor = MISC_DYNAMIC_MINOR, 308 .name = "sgi_fetchop", 309 .fops = &fetchop_fops 310 }; 311 312 static const struct file_operations cached_fops = { 313 .owner = THIS_MODULE, 314 .mmap = cached_mmap, 315 .llseek = noop_llseek, 316 }; 317 318 static struct miscdevice cached_miscdev = { 319 .minor = MISC_DYNAMIC_MINOR, 320 .name = "mspec_cached", 321 .fops = &cached_fops 322 }; 323 324 static const struct file_operations uncached_fops = { 325 .owner = THIS_MODULE, 326 .mmap = uncached_mmap, 327 .llseek = noop_llseek, 328 }; 329 330 static struct miscdevice uncached_miscdev = { 331 .minor = MISC_DYNAMIC_MINOR, 332 .name = "mspec_uncached", 333 .fops = &uncached_fops 334 }; 335 336 /* 337 * mspec_init 338 * 339 * Called at boot time to initialize the mspec facility. 340 */ 341 static int __init 342 mspec_init(void) 343 { 344 int ret; 345 int nid; 346 347 /* 348 * The fetchop device only works on SN2 hardware, uncached and cached 349 * memory drivers should both be valid on all ia64 hardware 350 */ 351 #ifdef CONFIG_SGI_SN 352 if (ia64_platform_is("sn2")) { 353 is_sn2 = 1; 354 if (is_shub2()) { 355 ret = -ENOMEM; 356 for_each_node_state(nid, N_ONLINE) { 357 int actual_nid; 358 int nasid; 359 unsigned long phys; 360 361 scratch_page[nid] = uncached_alloc_page(nid, 1); 362 if (scratch_page[nid] == 0) 363 goto free_scratch_pages; 364 phys = __pa(scratch_page[nid]); 365 nasid = get_node_number(phys); 366 actual_nid = nasid_to_cnodeid(nasid); 367 if (actual_nid != nid) 368 goto free_scratch_pages; 369 } 370 } 371 372 ret = misc_register(&fetchop_miscdev); 373 if (ret) { 374 printk(KERN_ERR 375 "%s: failed to register device %i\n", 376 FETCHOP_ID, ret); 377 goto free_scratch_pages; 378 } 379 } 380 #endif 381 ret = misc_register(&cached_miscdev); 382 if (ret) { 383 printk(KERN_ERR "%s: failed to register device %i\n", 384 CACHED_ID, ret); 385 if (is_sn2) 386 misc_deregister(&fetchop_miscdev); 387 goto free_scratch_pages; 388 } 389 ret = misc_register(&uncached_miscdev); 390 if (ret) { 391 printk(KERN_ERR "%s: failed to register device %i\n", 392 UNCACHED_ID, ret); 393 misc_deregister(&cached_miscdev); 394 if (is_sn2) 395 misc_deregister(&fetchop_miscdev); 396 goto free_scratch_pages; 397 } 398 399 printk(KERN_INFO "%s %s initialized devices: %s %s %s\n", 400 MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "", 401 CACHED_ID, UNCACHED_ID); 402 403 return 0; 404 405 free_scratch_pages: 406 for_each_node(nid) { 407 if (scratch_page[nid] != 0) 408 uncached_free_page(scratch_page[nid], 1); 409 } 410 return ret; 411 } 412 413 static void __exit 414 mspec_exit(void) 415 { 416 int nid; 417 418 misc_deregister(&uncached_miscdev); 419 misc_deregister(&cached_miscdev); 420 if (is_sn2) { 421 misc_deregister(&fetchop_miscdev); 422 423 for_each_node(nid) { 424 if (scratch_page[nid] != 0) 425 uncached_free_page(scratch_page[nid], 1); 426 } 427 } 428 } 429 430 module_init(mspec_init); 431 module_exit(mspec_exit); 432 433 MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>"); 434 MODULE_DESCRIPTION("Driver for SGI SN special memory operations"); 435 MODULE_LICENSE("GPL"); 436