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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
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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>
4e950f6f 41#include <linux/fs.h>
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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 <asm/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 */
4191ba26 70enum mspec_page_type {
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71 MSPEC_FETCHOP = 1,
72 MSPEC_CACHED,
73 MSPEC_UNCACHED
74};
75
1a4b0fc5 76#ifdef CONFIG_SGI_SN
17a3b050 77static int is_sn2;
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78#else
79#define is_sn2 0
80#endif
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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.
4191ba26
CW
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.
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91 */
92struct vma_data {
93 atomic_t refcnt; /* Number of vmas sharing the data. */
4191ba26 94 spinlock_t lock; /* Serialize access to this structure. */
17a3b050 95 int count; /* Number of pages allocated. */
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CW
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. */
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100 unsigned long maddr[0]; /* Array of MSPEC addresses. */
101};
102
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103#define VMD_VMALLOCED 0x1 /* vmalloc'd rather than kmalloc'd */
104
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105/* used on shub2 to clear FOP cache in the HUB */
106static unsigned long scratch_page[MAX_NUMNODES];
107#define SH2_AMO_CACHE_ENTRIES 4
108
109static inline int
110mspec_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
4191ba26
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142 * (via fork, munmap, etc.). Increments the reference count on the
143 * underlying mspec data so it is not freed prematurely.
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144 */
145static void
146mspec_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
afa684f6 158 * belonging to all the vma's sharing this vma_data structure.
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159 */
160static void
161mspec_close(struct vm_area_struct *vma)
162{
163 struct vma_data *vdata;
afa684f6 164 int index, last_index;
4191ba26 165 unsigned long my_page;
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166
167 vdata = vma->vm_private_data;
17a3b050 168
afa684f6
CW
169 if (!atomic_dec_and_test(&vdata->refcnt))
170 return;
4191ba26 171
afa684f6
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172 last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
173 for (index = 0; index < last_index; index++) {
4191ba26 174 if (vdata->maddr[index] == 0)
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175 continue;
176 /*
177 * Clear the page before sticking it back
178 * into the pool.
179 */
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180 my_page = vdata->maddr[index];
181 vdata->maddr[index] = 0;
afa684f6 182 if (!mspec_zero_block(my_page, PAGE_SIZE))
e4a064df 183 uncached_free_page(my_page, 1);
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184 else
185 printk(KERN_WARNING "mspec_close(): "
afa684f6 186 "failed to zero page %ld\n", my_page);
17a3b050 187 }
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188
189 if (vdata->flags & VMD_VMALLOCED)
17a3b050 190 vfree(vdata);
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191 else
192 kfree(vdata);
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193}
194
17a3b050 195/*
efe9e779 196 * mspec_fault
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197 *
198 * Creates a mspec page and maps it to user space.
199 */
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200static int
201mspec_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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202{
203 unsigned long paddr, maddr;
204 unsigned long pfn;
efe9e779 205 pgoff_t index = vmf->pgoff;
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206 struct vma_data *vdata = vma->vm_private_data;
207
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208 maddr = (volatile unsigned long) vdata->maddr[index];
209 if (maddr == 0) {
e4a064df 210 maddr = uncached_alloc_page(numa_node_id(), 1);
17a3b050 211 if (maddr == 0)
efe9e779 212 return VM_FAULT_OOM;
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213
214 spin_lock(&vdata->lock);
215 if (vdata->maddr[index] == 0) {
216 vdata->count++;
217 vdata->maddr[index] = maddr;
218 } else {
e4a064df 219 uncached_free_page(maddr, 1);
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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
1a4b0fc5 228 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
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229
230 pfn = paddr >> PAGE_SHIFT;
231
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NP
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;
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240}
241
f0f37e2f 242static const struct vm_operations_struct mspec_vm_ops = {
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243 .open = mspec_open,
244 .close = mspec_close,
efe9e779 245 .fault = mspec_fault,
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246};
247
248/*
249 * mspec_mmap
250 *
af901ca1 251 * Called when mmapping the device. Initializes the vma with a fault handler
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252 * and private data structure necessary to allocate, track, and free the
253 * underlying pages.
254 */
255static int
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256mspec_mmap(struct file *file, struct vm_area_struct *vma,
257 enum mspec_page_type type)
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258{
259 struct vma_data *vdata;
4191ba26 260 int pages, vdata_size, flags = 0;
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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 = kmalloc(vdata_size, GFP_KERNEL);
4191ba26 275 else {
17a3b050 276 vdata = vmalloc(vdata_size);
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277 flags = VMD_VMALLOCED;
278 }
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279 if (!vdata)
280 return -ENOMEM;
281 memset(vdata, 0, vdata_size);
282
4191ba26
CW
283 vdata->vm_start = vma->vm_start;
284 vdata->vm_end = vma->vm_end;
285 vdata->flags = flags;
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286 vdata->type = type;
287 spin_lock_init(&vdata->lock);
288 vdata->refcnt = ATOMIC_INIT(1);
289 vma->vm_private_data = vdata;
290
2f98735c 291 vma->vm_flags |= (VM_IO | VM_RESERVED | VM_PFNMAP | VM_DONTEXPAND);
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292 if (vdata->type == MSPEC_FETCHOP || vdata->type == MSPEC_UNCACHED)
293 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
294 vma->vm_ops = &mspec_vm_ops;
295
296 return 0;
297}
298
299static int
300fetchop_mmap(struct file *file, struct vm_area_struct *vma)
301{
302 return mspec_mmap(file, vma, MSPEC_FETCHOP);
303}
304
305static int
306cached_mmap(struct file *file, struct vm_area_struct *vma)
307{
308 return mspec_mmap(file, vma, MSPEC_CACHED);
309}
310
311static int
312uncached_mmap(struct file *file, struct vm_area_struct *vma)
313{
314 return mspec_mmap(file, vma, MSPEC_UNCACHED);
315}
316
2b8693c0 317static const struct file_operations fetchop_fops = {
17a3b050 318 .owner = THIS_MODULE,
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319 .mmap = fetchop_mmap,
320 .llseek = noop_llseek,
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321};
322
323static struct miscdevice fetchop_miscdev = {
324 .minor = MISC_DYNAMIC_MINOR,
325 .name = "sgi_fetchop",
326 .fops = &fetchop_fops
327};
328
2b8693c0 329static const struct file_operations cached_fops = {
17a3b050 330 .owner = THIS_MODULE,
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AB
331 .mmap = cached_mmap,
332 .llseek = noop_llseek,
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333};
334
335static struct miscdevice cached_miscdev = {
336 .minor = MISC_DYNAMIC_MINOR,
337 .name = "mspec_cached",
338 .fops = &cached_fops
339};
340
2b8693c0 341static const struct file_operations uncached_fops = {
17a3b050 342 .owner = THIS_MODULE,
6038f373
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343 .mmap = uncached_mmap,
344 .llseek = noop_llseek,
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345};
346
347static struct miscdevice uncached_miscdev = {
348 .minor = MISC_DYNAMIC_MINOR,
349 .name = "mspec_uncached",
350 .fops = &uncached_fops
351};
352
353/*
354 * mspec_init
355 *
356 * Called at boot time to initialize the mspec facility.
357 */
358static int __init
359mspec_init(void)
360{
361 int ret;
362 int nid;
363
364 /*
365 * The fetchop device only works on SN2 hardware, uncached and cached
366 * memory drivers should both be valid on all ia64 hardware
367 */
1a4b0fc5 368#ifdef CONFIG_SGI_SN
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369 if (ia64_platform_is("sn2")) {
370 is_sn2 = 1;
371 if (is_shub2()) {
372 ret = -ENOMEM;
2dca53a9 373 for_each_node_state(nid, N_ONLINE) {
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374 int actual_nid;
375 int nasid;
376 unsigned long phys;
377
e4a064df 378 scratch_page[nid] = uncached_alloc_page(nid, 1);
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379 if (scratch_page[nid] == 0)
380 goto free_scratch_pages;
381 phys = __pa(scratch_page[nid]);
382 nasid = get_node_number(phys);
383 actual_nid = nasid_to_cnodeid(nasid);
384 if (actual_nid != nid)
385 goto free_scratch_pages;
386 }
387 }
388
389 ret = misc_register(&fetchop_miscdev);
390 if (ret) {
391 printk(KERN_ERR
392 "%s: failed to register device %i\n",
393 FETCHOP_ID, ret);
394 goto free_scratch_pages;
395 }
396 }
1a4b0fc5 397#endif
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398 ret = misc_register(&cached_miscdev);
399 if (ret) {
400 printk(KERN_ERR "%s: failed to register device %i\n",
401 CACHED_ID, ret);
402 if (is_sn2)
403 misc_deregister(&fetchop_miscdev);
404 goto free_scratch_pages;
405 }
406 ret = misc_register(&uncached_miscdev);
407 if (ret) {
408 printk(KERN_ERR "%s: failed to register device %i\n",
409 UNCACHED_ID, ret);
410 misc_deregister(&cached_miscdev);
411 if (is_sn2)
412 misc_deregister(&fetchop_miscdev);
413 goto free_scratch_pages;
414 }
415
416 printk(KERN_INFO "%s %s initialized devices: %s %s %s\n",
417 MSPEC_BASENAME, REVISION, is_sn2 ? FETCHOP_ID : "",
418 CACHED_ID, UNCACHED_ID);
419
420 return 0;
421
422 free_scratch_pages:
423 for_each_node(nid) {
424 if (scratch_page[nid] != 0)
e4a064df 425 uncached_free_page(scratch_page[nid], 1);
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426 }
427 return ret;
428}
429
430static void __exit
431mspec_exit(void)
432{
433 int nid;
434
435 misc_deregister(&uncached_miscdev);
436 misc_deregister(&cached_miscdev);
437 if (is_sn2) {
438 misc_deregister(&fetchop_miscdev);
439
440 for_each_node(nid) {
441 if (scratch_page[nid] != 0)
e4a064df 442 uncached_free_page(scratch_page[nid], 1);
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443 }
444 }
445}
446
447module_init(mspec_init);
448module_exit(mspec_exit);
449
450MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
451MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
452MODULE_LICENSE("GPL");