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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 two types of memory made available thru this driver:
13 * uncached and cached.
14 *
15 * Uncached are used for memory write combining feature of the ia64
16 * cpu.
17 *
18 * Cached are used for areas of memory that are used as cached addresses
19 * on our partition and used as uncached addresses from other partitions.
20 * Due to a design constraint of the SN2 Shub, you can not have processors
21 * on the same FSB perform both a cached and uncached reference to the
22 * same cache line. These special memory cached regions prevent the
23 * kernel from ever dropping in a TLB entry and therefore prevent the
24 * processor from ever speculating a cache line from this page.
25 */
26
27#include <linux/types.h>
28#include <linux/kernel.h>
29#include <linux/module.h>
30#include <linux/init.h>
31#include <linux/errno.h>
32#include <linux/miscdevice.h>
33#include <linux/spinlock.h>
34#include <linux/mm.h>
35#include <linux/fs.h>
36#include <linux/vmalloc.h>
37#include <linux/string.h>
38#include <linux/slab.h>
39#include <linux/numa.h>
40#include <linux/refcount.h>
41#include <asm/page.h>
42#include <asm/pgtable.h>
43#include <linux/atomic.h>
44#include <asm/tlbflush.h>
45#include <asm/uncached.h>
46
47
48#define CACHED_ID "Cached,"
49#define UNCACHED_ID "Uncached"
50#define REVISION "4.0"
51#define MSPEC_BASENAME "mspec"
52
53/*
54 * Page types allocated by the device.
55 */
56enum mspec_page_type {
57 MSPEC_CACHED = 2,
58 MSPEC_UNCACHED
59};
60
61/*
62 * One of these structures is allocated when an mspec region is mmaped. The
63 * structure is pointed to by the vma->vm_private_data field in the vma struct.
64 * This structure is used to record the addresses of the mspec pages.
65 * This structure is shared by all vma's that are split off from the
66 * original vma when split_vma()'s are done.
67 *
68 * The refcnt is incremented atomically because mm->mmap_sem does not
69 * protect in fork case where multiple tasks share the vma_data.
70 */
71struct vma_data {
72 refcount_t refcnt; /* Number of vmas sharing the data. */
73 spinlock_t lock; /* Serialize access to this structure. */
74 int count; /* Number of pages allocated. */
75 enum mspec_page_type type; /* Type of pages allocated. */
76 unsigned long vm_start; /* Original (unsplit) base. */
77 unsigned long vm_end; /* Original (unsplit) end. */
78 unsigned long maddr[0]; /* Array of MSPEC addresses. */
79};
80
81/*
82 * mspec_open
83 *
84 * Called when a device mapping is created by a means other than mmap
85 * (via fork, munmap, etc.). Increments the reference count on the
86 * underlying mspec data so it is not freed prematurely.
87 */
88static void
89mspec_open(struct vm_area_struct *vma)
90{
91 struct vma_data *vdata;
92
93 vdata = vma->vm_private_data;
94 refcount_inc(&vdata->refcnt);
95}
96
97/*
98 * mspec_close
99 *
100 * Called when unmapping a device mapping. Frees all mspec pages
101 * belonging to all the vma's sharing this vma_data structure.
102 */
103static void
104mspec_close(struct vm_area_struct *vma)
105{
106 struct vma_data *vdata;
107 int index, last_index;
108 unsigned long my_page;
109
110 vdata = vma->vm_private_data;
111
112 if (!refcount_dec_and_test(&vdata->refcnt))
113 return;
114
115 last_index = (vdata->vm_end - vdata->vm_start) >> PAGE_SHIFT;
116 for (index = 0; index < last_index; index++) {
117 if (vdata->maddr[index] == 0)
118 continue;
119 /*
120 * Clear the page before sticking it back
121 * into the pool.
122 */
123 my_page = vdata->maddr[index];
124 vdata->maddr[index] = 0;
125 memset((char *)my_page, 0, PAGE_SIZE);
126 uncached_free_page(my_page, 1);
127 }
128
129 kvfree(vdata);
130}
131
132/*
133 * mspec_fault
134 *
135 * Creates a mspec page and maps it to user space.
136 */
137static vm_fault_t
138mspec_fault(struct vm_fault *vmf)
139{
140 unsigned long paddr, maddr;
141 unsigned long pfn;
142 pgoff_t index = vmf->pgoff;
143 struct vma_data *vdata = vmf->vma->vm_private_data;
144
145 maddr = (volatile unsigned long) vdata->maddr[index];
146 if (maddr == 0) {
147 maddr = uncached_alloc_page(numa_node_id(), 1);
148 if (maddr == 0)
149 return VM_FAULT_OOM;
150
151 spin_lock(&vdata->lock);
152 if (vdata->maddr[index] == 0) {
153 vdata->count++;
154 vdata->maddr[index] = maddr;
155 } else {
156 uncached_free_page(maddr, 1);
157 maddr = vdata->maddr[index];
158 }
159 spin_unlock(&vdata->lock);
160 }
161
162 paddr = maddr & ~__IA64_UNCACHED_OFFSET;
163 pfn = paddr >> PAGE_SHIFT;
164
165 return vmf_insert_pfn(vmf->vma, vmf->address, pfn);
166}
167
168static const struct vm_operations_struct mspec_vm_ops = {
169 .open = mspec_open,
170 .close = mspec_close,
171 .fault = mspec_fault,
172};
173
174/*
175 * mspec_mmap
176 *
177 * Called when mmapping the device. Initializes the vma with a fault handler
178 * and private data structure necessary to allocate, track, and free the
179 * underlying pages.
180 */
181static int
182mspec_mmap(struct file *file, struct vm_area_struct *vma,
183 enum mspec_page_type type)
184{
185 struct vma_data *vdata;
186 int pages, vdata_size;
187
188 if (vma->vm_pgoff != 0)
189 return -EINVAL;
190
191 if ((vma->vm_flags & VM_SHARED) == 0)
192 return -EINVAL;
193
194 if ((vma->vm_flags & VM_WRITE) == 0)
195 return -EPERM;
196
197 pages = vma_pages(vma);
198 vdata_size = sizeof(struct vma_data) + pages * sizeof(long);
199 if (vdata_size <= PAGE_SIZE)
200 vdata = kzalloc(vdata_size, GFP_KERNEL);
201 else
202 vdata = vzalloc(vdata_size);
203 if (!vdata)
204 return -ENOMEM;
205
206 vdata->vm_start = vma->vm_start;
207 vdata->vm_end = vma->vm_end;
208 vdata->type = type;
209 spin_lock_init(&vdata->lock);
210 refcount_set(&vdata->refcnt, 1);
211 vma->vm_private_data = vdata;
212
213 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
214 if (vdata->type == MSPEC_UNCACHED)
215 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
216 vma->vm_ops = &mspec_vm_ops;
217
218 return 0;
219}
220
221static int
222cached_mmap(struct file *file, struct vm_area_struct *vma)
223{
224 return mspec_mmap(file, vma, MSPEC_CACHED);
225}
226
227static int
228uncached_mmap(struct file *file, struct vm_area_struct *vma)
229{
230 return mspec_mmap(file, vma, MSPEC_UNCACHED);
231}
232
233static const struct file_operations cached_fops = {
234 .owner = THIS_MODULE,
235 .mmap = cached_mmap,
236 .llseek = noop_llseek,
237};
238
239static struct miscdevice cached_miscdev = {
240 .minor = MISC_DYNAMIC_MINOR,
241 .name = "mspec_cached",
242 .fops = &cached_fops
243};
244
245static const struct file_operations uncached_fops = {
246 .owner = THIS_MODULE,
247 .mmap = uncached_mmap,
248 .llseek = noop_llseek,
249};
250
251static struct miscdevice uncached_miscdev = {
252 .minor = MISC_DYNAMIC_MINOR,
253 .name = "mspec_uncached",
254 .fops = &uncached_fops
255};
256
257/*
258 * mspec_init
259 *
260 * Called at boot time to initialize the mspec facility.
261 */
262static int __init
263mspec_init(void)
264{
265 int ret;
266
267 ret = misc_register(&cached_miscdev);
268 if (ret) {
269 printk(KERN_ERR "%s: failed to register device %i\n",
270 CACHED_ID, ret);
271 return ret;
272 }
273 ret = misc_register(&uncached_miscdev);
274 if (ret) {
275 printk(KERN_ERR "%s: failed to register device %i\n",
276 UNCACHED_ID, ret);
277 misc_deregister(&cached_miscdev);
278 return ret;
279 }
280
281 printk(KERN_INFO "%s %s initialized devices: %s %s\n",
282 MSPEC_BASENAME, REVISION, CACHED_ID, UNCACHED_ID);
283
284 return 0;
285}
286
287static void __exit
288mspec_exit(void)
289{
290 misc_deregister(&uncached_miscdev);
291 misc_deregister(&cached_miscdev);
292}
293
294module_init(mspec_init);
295module_exit(mspec_exit);
296
297MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
298MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
299MODULE_LICENSE("GPL");
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 */
69enum mspec_page_type {
70 MSPEC_FETCHOP = 1,
71 MSPEC_CACHED,
72 MSPEC_UNCACHED
73};
74
75#ifdef CONFIG_SGI_SN
76static 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 */
91struct 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 */
105static unsigned long scratch_page[MAX_NUMNODES];
106#define SH2_AMO_CACHE_ENTRIES 4
107
108static inline int
109mspec_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 */
144static void
145mspec_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 */
159static void
160mspec_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 */
199static int
200mspec_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
241static 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 */
254static int
255mspec_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
297static int
298fetchop_mmap(struct file *file, struct vm_area_struct *vma)
299{
300 return mspec_mmap(file, vma, MSPEC_FETCHOP);
301}
302
303static int
304cached_mmap(struct file *file, struct vm_area_struct *vma)
305{
306 return mspec_mmap(file, vma, MSPEC_CACHED);
307}
308
309static int
310uncached_mmap(struct file *file, struct vm_area_struct *vma)
311{
312 return mspec_mmap(file, vma, MSPEC_UNCACHED);
313}
314
315static const struct file_operations fetchop_fops = {
316 .owner = THIS_MODULE,
317 .mmap = fetchop_mmap,
318 .llseek = noop_llseek,
319};
320
321static struct miscdevice fetchop_miscdev = {
322 .minor = MISC_DYNAMIC_MINOR,
323 .name = "sgi_fetchop",
324 .fops = &fetchop_fops
325};
326
327static const struct file_operations cached_fops = {
328 .owner = THIS_MODULE,
329 .mmap = cached_mmap,
330 .llseek = noop_llseek,
331};
332
333static struct miscdevice cached_miscdev = {
334 .minor = MISC_DYNAMIC_MINOR,
335 .name = "mspec_cached",
336 .fops = &cached_fops
337};
338
339static const struct file_operations uncached_fops = {
340 .owner = THIS_MODULE,
341 .mmap = uncached_mmap,
342 .llseek = noop_llseek,
343};
344
345static 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 */
356static int __init
357mspec_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
428static void __exit
429mspec_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
445module_init(mspec_init);
446module_exit(mspec_exit);
447
448MODULE_AUTHOR("Silicon Graphics, Inc. <linux-altix@sgi.com>");
449MODULE_DESCRIPTION("Driver for SGI SN special memory operations");
450MODULE_LICENSE("GPL");