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1/* adi_64.c: support for ADI (Application Data Integrity) feature on
2 * sparc m7 and newer processors. This feature is also known as
3 * SSM (Silicon Secured Memory).
4 *
5 * Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
6 * Author: Khalid Aziz (khalid.aziz@oracle.com)
7 *
8 * This work is licensed under the terms of the GNU GPL, version 2.
9 */
10#include <linux/init.h>
11#include <linux/slab.h>
12#include <linux/mm_types.h>
13#include <asm/mdesc.h>
14#include <asm/adi_64.h>
15#include <asm/mmu_64.h>
16#include <asm/pgtable_64.h>
17
18/* Each page of storage for ADI tags can accommodate tags for 128
19 * pages. When ADI enabled pages are being swapped out, it would be
20 * prudent to allocate at least enough tag storage space to accommodate
21 * SWAPFILE_CLUSTER number of pages. Allocate enough tag storage to
22 * store tags for four SWAPFILE_CLUSTER pages to reduce need for
23 * further allocations for same vma.
24 */
25#define TAG_STORAGE_PAGES 8
26
27struct adi_config adi_state;
28EXPORT_SYMBOL(adi_state);
29
30/* mdesc_adi_init() : Parse machine description provided by the
31 * hypervisor to detect ADI capabilities
32 *
33 * Hypervisor reports ADI capabilities of platform in "hwcap-list" property
34 * for "cpu" node. If the platform supports ADI, "hwcap-list" property
35 * contains the keyword "adp". If the platform supports ADI, "platform"
36 * node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
37 * to describe the ADI capabilities.
38 */
39void __init mdesc_adi_init(void)
40{
41 struct mdesc_handle *hp = mdesc_grab();
42 const char *prop;
43 u64 pn, *val;
44 int len;
45
46 if (!hp)
47 goto adi_not_found;
48
49 pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
50 if (pn == MDESC_NODE_NULL)
51 goto adi_not_found;
52
53 prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
54 if (!prop)
55 goto adi_not_found;
56
57 /*
58 * Look for "adp" keyword in hwcap-list which would indicate
59 * ADI support
60 */
61 adi_state.enabled = false;
62 while (len) {
63 int plen;
64
65 if (!strcmp(prop, "adp")) {
66 adi_state.enabled = true;
67 break;
68 }
69
70 plen = strlen(prop) + 1;
71 prop += plen;
72 len -= plen;
73 }
74
75 if (!adi_state.enabled)
76 goto adi_not_found;
77
78 /* Find the ADI properties in "platform" node. If all ADI
79 * properties are not found, ADI support is incomplete and
80 * do not enable ADI in the kernel.
81 */
82 pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
83 if (pn == MDESC_NODE_NULL)
84 goto adi_not_found;
85
86 val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
87 if (!val)
88 goto adi_not_found;
89 adi_state.caps.blksz = *val;
90
91 val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
92 if (!val)
93 goto adi_not_found;
94 adi_state.caps.nbits = *val;
95
96 val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
97 if (!val)
98 goto adi_not_found;
99 adi_state.caps.ue_on_adi = *val;
100
101 /* Some of the code to support swapping ADI tags is written
102 * assumption that two ADI tags can fit inside one byte. If
103 * this assumption is broken by a future architecture change,
104 * that code will have to be revisited. If that were to happen,
105 * disable ADI support so we do not get unpredictable results
106 * with programs trying to use ADI and their pages getting
107 * swapped out
108 */
109 if (adi_state.caps.nbits > 4) {
110 pr_warn("WARNING: ADI tag size >4 on this platform. Disabling AADI support\n");
111 adi_state.enabled = false;
112 }
113
114 mdesc_release(hp);
115 return;
116
117adi_not_found:
118 adi_state.enabled = false;
119 adi_state.caps.blksz = 0;
120 adi_state.caps.nbits = 0;
121 if (hp)
122 mdesc_release(hp);
123}
124
125tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
126 struct vm_area_struct *vma,
127 unsigned long addr)
128{
129 tag_storage_desc_t *tag_desc = NULL;
130 unsigned long i, max_desc, flags;
131
132 /* Check if this vma already has tag storage descriptor
133 * allocated for it.
134 */
135 max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
136 if (mm->context.tag_store) {
137 tag_desc = mm->context.tag_store;
138 spin_lock_irqsave(&mm->context.tag_lock, flags);
139 for (i = 0; i < max_desc; i++) {
140 if ((addr >= tag_desc->start) &&
141 ((addr + PAGE_SIZE - 1) <= tag_desc->end))
142 break;
143 tag_desc++;
144 }
145 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
146
147 /* If no matching entries were found, this must be a
148 * freshly allocated page
149 */
150 if (i >= max_desc)
151 tag_desc = NULL;
152 }
153
154 return tag_desc;
155}
156
157tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
158 struct vm_area_struct *vma,
159 unsigned long addr)
160{
161 unsigned char *tags;
162 unsigned long i, size, max_desc, flags;
163 tag_storage_desc_t *tag_desc, *open_desc;
164 unsigned long end_addr, hole_start, hole_end;
165
166 max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
167 open_desc = NULL;
168 hole_start = 0;
169 hole_end = ULONG_MAX;
170 end_addr = addr + PAGE_SIZE - 1;
171
172 /* Check if this vma already has tag storage descriptor
173 * allocated for it.
174 */
175 spin_lock_irqsave(&mm->context.tag_lock, flags);
176 if (mm->context.tag_store) {
177 tag_desc = mm->context.tag_store;
178
179 /* Look for a matching entry for this address. While doing
180 * that, look for the first open slot as well and find
181 * the hole in already allocated range where this request
182 * will fit in.
183 */
184 for (i = 0; i < max_desc; i++) {
185 if (tag_desc->tag_users == 0) {
186 if (open_desc == NULL)
187 open_desc = tag_desc;
188 } else {
189 if ((addr >= tag_desc->start) &&
190 (tag_desc->end >= (addr + PAGE_SIZE - 1))) {
191 tag_desc->tag_users++;
192 goto out;
193 }
194 }
195 if ((tag_desc->start > end_addr) &&
196 (tag_desc->start < hole_end))
197 hole_end = tag_desc->start;
198 if ((tag_desc->end < addr) &&
199 (tag_desc->end > hole_start))
200 hole_start = tag_desc->end;
201 tag_desc++;
202 }
203
204 } else {
205 size = sizeof(tag_storage_desc_t)*max_desc;
206 mm->context.tag_store = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
207 if (mm->context.tag_store == NULL) {
208 tag_desc = NULL;
209 goto out;
210 }
211 tag_desc = mm->context.tag_store;
212 for (i = 0; i < max_desc; i++, tag_desc++)
213 tag_desc->tag_users = 0;
214 open_desc = mm->context.tag_store;
215 i = 0;
216 }
217
218 /* Check if we ran out of tag storage descriptors */
219 if (open_desc == NULL) {
220 tag_desc = NULL;
221 goto out;
222 }
223
224 /* Mark this tag descriptor slot in use and then initialize it */
225 tag_desc = open_desc;
226 tag_desc->tag_users = 1;
227
228 /* Tag storage has not been allocated for this vma and space
229 * is available in tag storage descriptor. Since this page is
230 * being swapped out, there is high probability subsequent pages
231 * in the VMA will be swapped out as well. Allocate pages to
232 * store tags for as many pages in this vma as possible but not
233 * more than TAG_STORAGE_PAGES. Each byte in tag space holds
234 * two ADI tags since each ADI tag is 4 bits. Each ADI tag
235 * covers adi_blksize() worth of addresses. Check if the hole is
236 * big enough to accommodate full address range for using
237 * TAG_STORAGE_PAGES number of tag pages.
238 */
239 size = TAG_STORAGE_PAGES * PAGE_SIZE;
240 end_addr = addr + (size*2*adi_blksize()) - 1;
241 /* Check for overflow. If overflow occurs, allocate only one page */
242 if (end_addr < addr) {
243 size = PAGE_SIZE;
244 end_addr = addr + (size*2*adi_blksize()) - 1;
245 /* If overflow happens with the minimum tag storage
246 * allocation as well, adjust ending address for this
247 * tag storage.
248 */
249 if (end_addr < addr)
250 end_addr = ULONG_MAX;
251 }
252 if (hole_end < end_addr) {
253 /* Available hole is too small on the upper end of
254 * address. Can we expand the range towards the lower
255 * address and maximize use of this slot?
256 */
257 unsigned long tmp_addr;
258
259 end_addr = hole_end - 1;
260 tmp_addr = end_addr - (size*2*adi_blksize()) + 1;
261 /* Check for underflow. If underflow occurs, allocate
262 * only one page for storing ADI tags
263 */
264 if (tmp_addr > addr) {
265 size = PAGE_SIZE;
266 tmp_addr = end_addr - (size*2*adi_blksize()) - 1;
267 /* If underflow happens with the minimum tag storage
268 * allocation as well, adjust starting address for
269 * this tag storage.
270 */
271 if (tmp_addr > addr)
272 tmp_addr = 0;
273 }
274 if (tmp_addr < hole_start) {
275 /* Available hole is restricted on lower address
276 * end as well
277 */
278 tmp_addr = hole_start + 1;
279 }
280 addr = tmp_addr;
281 size = (end_addr + 1 - addr)/(2*adi_blksize());
282 size = (size + (PAGE_SIZE-adi_blksize()))/PAGE_SIZE;
283 size = size * PAGE_SIZE;
284 }
285 tags = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
286 if (tags == NULL) {
287 tag_desc->tag_users = 0;
288 tag_desc = NULL;
289 goto out;
290 }
291 tag_desc->start = addr;
292 tag_desc->tags = tags;
293 tag_desc->end = end_addr;
294
295out:
296 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
297 return tag_desc;
298}
299
300void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
301{
302 unsigned long flags;
303 unsigned char *tags = NULL;
304
305 spin_lock_irqsave(&mm->context.tag_lock, flags);
306 tag_desc->tag_users--;
307 if (tag_desc->tag_users == 0) {
308 tag_desc->start = tag_desc->end = 0;
309 /* Do not free up the tag storage space allocated
310 * by the first descriptor. This is persistent
311 * emergency tag storage space for the task.
312 */
313 if (tag_desc != mm->context.tag_store) {
314 tags = tag_desc->tags;
315 tag_desc->tags = NULL;
316 }
317 }
318 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
319 kfree(tags);
320}
321
322#define tag_start(addr, tag_desc) \
323 ((tag_desc)->tags + ((addr - (tag_desc)->start)/(2*adi_blksize())))
324
325/* Retrieve any saved ADI tags for the page being swapped back in and
326 * restore these tags to the newly allocated physical page.
327 */
328void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
329 unsigned long addr, pte_t pte)
330{
331 unsigned char *tag;
332 tag_storage_desc_t *tag_desc;
333 unsigned long paddr, tmp, version1, version2;
334
335 /* Check if the swapped out page has an ADI version
336 * saved. If yes, restore version tag to the newly
337 * allocated page.
338 */
339 tag_desc = find_tag_store(mm, vma, addr);
340 if (tag_desc == NULL)
341 return;
342
343 tag = tag_start(addr, tag_desc);
344 paddr = pte_val(pte) & _PAGE_PADDR_4V;
345 for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
346 version1 = (*tag) >> 4;
347 version2 = (*tag) & 0x0f;
348 *tag++ = 0;
349 asm volatile("stxa %0, [%1] %2\n\t"
350 :
351 : "r" (version1), "r" (tmp),
352 "i" (ASI_MCD_REAL));
353 tmp += adi_blksize();
354 asm volatile("stxa %0, [%1] %2\n\t"
355 :
356 : "r" (version2), "r" (tmp),
357 "i" (ASI_MCD_REAL));
358 }
359 asm volatile("membar #Sync\n\t");
360
361 /* Check and mark this tag space for release later if
362 * the swapped in page was the last user of tag space
363 */
364 del_tag_store(tag_desc, mm);
365}
366
367/* A page is about to be swapped out. Save any ADI tags associated with
368 * this physical page so they can be restored later when the page is swapped
369 * back in.
370 */
371int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
372 unsigned long addr, pte_t oldpte)
373{
374 unsigned char *tag;
375 tag_storage_desc_t *tag_desc;
376 unsigned long version1, version2, paddr, tmp;
377
378 tag_desc = alloc_tag_store(mm, vma, addr);
379 if (tag_desc == NULL)
380 return -1;
381
382 tag = tag_start(addr, tag_desc);
383 paddr = pte_val(oldpte) & _PAGE_PADDR_4V;
384 for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
385 asm volatile("ldxa [%1] %2, %0\n\t"
386 : "=r" (version1)
387 : "r" (tmp), "i" (ASI_MCD_REAL));
388 tmp += adi_blksize();
389 asm volatile("ldxa [%1] %2, %0\n\t"
390 : "=r" (version2)
391 : "r" (tmp), "i" (ASI_MCD_REAL));
392 *tag = (version1 << 4) | version2;
393 tag++;
394 }
395
396 return 0;
397}