1 // SPDX-License-Identifier: GPL-2.0-only
2 /* adi_64.c: support for ADI (Application Data Integrity) feature on
3 * sparc m7 and newer processors. This feature is also known as
4 * SSM (Silicon Secured Memory).
5 *
6 * Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
7 * Author: Khalid Aziz (khalid.aziz@oracle.com)
8 */
9 #include <linux/init.h>
10 #include <linux/slab.h>
11 #include <linux/mm_types.h>
12 #include <asm/mdesc.h>
13 #include <asm/adi_64.h>
14 #include <asm/mmu_64.h>
15 #include <asm/pgtable_64.h>
16
17 /* Each page of storage for ADI tags can accommodate tags for 128
18 * pages. When ADI enabled pages are being swapped out, it would be
19 * prudent to allocate at least enough tag storage space to accommodate
20 * SWAPFILE_CLUSTER number of pages. Allocate enough tag storage to
21 * store tags for four SWAPFILE_CLUSTER pages to reduce need for
22 * further allocations for same vma.
23 */
24 #define TAG_STORAGE_PAGES 8
25
26 struct adi_config adi_state;
27 EXPORT_SYMBOL(adi_state);
28
29 /* mdesc_adi_init() : Parse machine description provided by the
30 * hypervisor to detect ADI capabilities
31 *
32 * Hypervisor reports ADI capabilities of platform in "hwcap-list" property
33 * for "cpu" node. If the platform supports ADI, "hwcap-list" property
34 * contains the keyword "adp". If the platform supports ADI, "platform"
35 * node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
36 * to describe the ADI capabilities.
37 */
38 void __init mdesc_adi_init(void)
39 {
40 struct mdesc_handle *hp = mdesc_grab();
41 const char *prop;
42 u64 pn, *val;
43 int len;
44
45 if (!hp)
46 goto adi_not_found;
47
48 pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
49 if (pn == MDESC_NODE_NULL)
50 goto adi_not_found;
51
52 prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
53 if (!prop)
54 goto adi_not_found;
55
56 /*
57 * Look for "adp" keyword in hwcap-list which would indicate
58 * ADI support
59 */
60 adi_state.enabled = false;
61 while (len) {
62 int plen;
63
64 if (!strcmp(prop, "adp")) {
65 adi_state.enabled = true;
66 break;
67 }
68
69 plen = strlen(prop) + 1;
70 prop += plen;
71 len -= plen;
72 }
73
74 if (!adi_state.enabled)
75 goto adi_not_found;
76
77 /* Find the ADI properties in "platform" node. If all ADI
78 * properties are not found, ADI support is incomplete and
79 * do not enable ADI in the kernel.
80 */
81 pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
82 if (pn == MDESC_NODE_NULL)
83 goto adi_not_found;
84
85 val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
86 if (!val)
87 goto adi_not_found;
88 adi_state.caps.blksz = *val;
89
90 val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
91 if (!val)
92 goto adi_not_found;
93 adi_state.caps.nbits = *val;
94
95 val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
96 if (!val)
97 goto adi_not_found;
98 adi_state.caps.ue_on_adi = *val;
99
100 /* Some of the code to support swapping ADI tags is written
101 * assumption that two ADI tags can fit inside one byte. If
102 * this assumption is broken by a future architecture change,
103 * that code will have to be revisited. If that were to happen,
104 * disable ADI support so we do not get unpredictable results
105 * with programs trying to use ADI and their pages getting
106 * swapped out
107 */
108 if (adi_state.caps.nbits > 4) {
109 pr_warn("WARNING: ADI tag size >4 on this platform. Disabling AADI support\n");
110 adi_state.enabled = false;
111 }
112
113 mdesc_release(hp);
114 return;
115
116 adi_not_found:
117 adi_state.enabled = false;
118 adi_state.caps.blksz = 0;
119 adi_state.caps.nbits = 0;
120 if (hp)
121 mdesc_release(hp);
122 }
123
124 tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
125 struct vm_area_struct *vma,
126 unsigned long addr)
127 {
128 tag_storage_desc_t *tag_desc = NULL;
129 unsigned long i, max_desc, flags;
130
131 /* Check if this vma already has tag storage descriptor
132 * allocated for it.
133 */
134 max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
135 if (mm->context.tag_store) {
136 tag_desc = mm->context.tag_store;
137 spin_lock_irqsave(&mm->context.tag_lock, flags);
138 for (i = 0; i < max_desc; i++) {
139 if ((addr >= tag_desc->start) &&
140 ((addr + PAGE_SIZE - 1) <= tag_desc->end))
141 break;
142 tag_desc++;
143 }
144 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
145
146 /* If no matching entries were found, this must be a
147 * freshly allocated page
148 */
149 if (i >= max_desc)
150 tag_desc = NULL;
151 }
152
153 return tag_desc;
154 }
155
156 tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
157 struct vm_area_struct *vma,
158 unsigned long addr)
159 {
160 unsigned char *tags;
161 unsigned long i, size, max_desc, flags;
162 tag_storage_desc_t *tag_desc, *open_desc;
163 unsigned long end_addr, hole_start, hole_end;
164
165 max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
166 open_desc = NULL;
167 hole_start = 0;
168 hole_end = ULONG_MAX;
169 end_addr = addr + PAGE_SIZE - 1;
170
171 /* Check if this vma already has tag storage descriptor
172 * allocated for it.
173 */
174 spin_lock_irqsave(&mm->context.tag_lock, flags);
175 if (mm->context.tag_store) {
176 tag_desc = mm->context.tag_store;
177
178 /* Look for a matching entry for this address. While doing
179 * that, look for the first open slot as well and find
180 * the hole in already allocated range where this request
181 * will fit in.
182 */
183 for (i = 0; i < max_desc; i++) {
184 if (tag_desc->tag_users == 0) {
185 if (open_desc == NULL)
186 open_desc = tag_desc;
187 } else {
188 if ((addr >= tag_desc->start) &&
189 (tag_desc->end >= (addr + PAGE_SIZE - 1))) {
190 tag_desc->tag_users++;
191 goto out;
192 }
193 }
194 if ((tag_desc->start > end_addr) &&
195 (tag_desc->start < hole_end))
196 hole_end = tag_desc->start;
197 if ((tag_desc->end < addr) &&
198 (tag_desc->end > hole_start))
199 hole_start = tag_desc->end;
200 tag_desc++;
201 }
202
203 } else {
204 size = sizeof(tag_storage_desc_t)*max_desc;
205 mm->context.tag_store = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
206 if (mm->context.tag_store == NULL) {
207 tag_desc = NULL;
208 goto out;
209 }
210 tag_desc = mm->context.tag_store;
211 for (i = 0; i < max_desc; i++, tag_desc++)
212 tag_desc->tag_users = 0;
213 open_desc = mm->context.tag_store;
214 i = 0;
215 }
216
217 /* Check if we ran out of tag storage descriptors */
218 if (open_desc == NULL) {
219 tag_desc = NULL;
220 goto out;
221 }
222
223 /* Mark this tag descriptor slot in use and then initialize it */
224 tag_desc = open_desc;
225 tag_desc->tag_users = 1;
226
227 /* Tag storage has not been allocated for this vma and space
228 * is available in tag storage descriptor. Since this page is
229 * being swapped out, there is high probability subsequent pages
230 * in the VMA will be swapped out as well. Allocate pages to
231 * store tags for as many pages in this vma as possible but not
232 * more than TAG_STORAGE_PAGES. Each byte in tag space holds
233 * two ADI tags since each ADI tag is 4 bits. Each ADI tag
234 * covers adi_blksize() worth of addresses. Check if the hole is
235 * big enough to accommodate full address range for using
236 * TAG_STORAGE_PAGES number of tag pages.
237 */
238 size = TAG_STORAGE_PAGES * PAGE_SIZE;
239 end_addr = addr + (size*2*adi_blksize()) - 1;
240 /* Check for overflow. If overflow occurs, allocate only one page */
241 if (end_addr < addr) {
242 size = PAGE_SIZE;
243 end_addr = addr + (size*2*adi_blksize()) - 1;
244 /* If overflow happens with the minimum tag storage
245 * allocation as well, adjust ending address for this
246 * tag storage.
247 */
248 if (end_addr < addr)
249 end_addr = ULONG_MAX;
250 }
251 if (hole_end < end_addr) {
252 /* Available hole is too small on the upper end of
253 * address. Can we expand the range towards the lower
254 * address and maximize use of this slot?
255 */
256 unsigned long tmp_addr;
257
258 end_addr = hole_end - 1;
259 tmp_addr = end_addr - (size*2*adi_blksize()) + 1;
260 /* Check for underflow. If underflow occurs, allocate
261 * only one page for storing ADI tags
262 */
263 if (tmp_addr > addr) {
264 size = PAGE_SIZE;
265 tmp_addr = end_addr - (size*2*adi_blksize()) - 1;
266 /* If underflow happens with the minimum tag storage
267 * allocation as well, adjust starting address for
268 * this tag storage.
269 */
270 if (tmp_addr > addr)
271 tmp_addr = 0;
272 }
273 if (tmp_addr < hole_start) {
274 /* Available hole is restricted on lower address
275 * end as well
276 */
277 tmp_addr = hole_start + 1;
278 }
279 addr = tmp_addr;
280 size = (end_addr + 1 - addr)/(2*adi_blksize());
281 size = (size + (PAGE_SIZE-adi_blksize()))/PAGE_SIZE;
282 size = size * PAGE_SIZE;
283 }
284 tags = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
285 if (tags == NULL) {
286 tag_desc->tag_users = 0;
287 tag_desc = NULL;
288 goto out;
289 }
290 tag_desc->start = addr;
291 tag_desc->tags = tags;
292 tag_desc->end = end_addr;
293
294 out:
295 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
296 return tag_desc;
297 }
298
299 void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
300 {
301 unsigned long flags;
302 unsigned char *tags = NULL;
303
304 spin_lock_irqsave(&mm->context.tag_lock, flags);
305 tag_desc->tag_users--;
306 if (tag_desc->tag_users == 0) {
307 tag_desc->start = tag_desc->end = 0;
308 /* Do not free up the tag storage space allocated
309 * by the first descriptor. This is persistent
310 * emergency tag storage space for the task.
311 */
312 if (tag_desc != mm->context.tag_store) {
313 tags = tag_desc->tags;
314 tag_desc->tags = NULL;
315 }
316 }
317 spin_unlock_irqrestore(&mm->context.tag_lock, flags);
318 kfree(tags);
319 }
320
321 #define tag_start(addr, tag_desc) \
322 ((tag_desc)->tags + ((addr - (tag_desc)->start)/(2*adi_blksize())))
323
324 /* Retrieve any saved ADI tags for the page being swapped back in and
325 * restore these tags to the newly allocated physical page.
326 */
327 void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
328 unsigned long addr, pte_t pte)
329 {
330 unsigned char *tag;
331 tag_storage_desc_t *tag_desc;
332 unsigned long paddr, tmp, version1, version2;
333
334 /* Check if the swapped out page has an ADI version
335 * saved. If yes, restore version tag to the newly
336 * allocated page.
337 */
338 tag_desc = find_tag_store(mm, vma, addr);
339 if (tag_desc == NULL)
340 return;
341
342 tag = tag_start(addr, tag_desc);
343 paddr = pte_val(pte) & _PAGE_PADDR_4V;
344 for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
345 version1 = (*tag) >> 4;
346 version2 = (*tag) & 0x0f;
347 *tag++ = 0;
348 asm volatile("stxa %0, [%1] %2\n\t"
349 :
350 : "r" (version1), "r" (tmp),
351 "i" (ASI_MCD_REAL));
352 tmp += adi_blksize();
353 asm volatile("stxa %0, [%1] %2\n\t"
354 :
355 : "r" (version2), "r" (tmp),
356 "i" (ASI_MCD_REAL));
357 }
358 asm volatile("membar #Sync\n\t");
359
360 /* Check and mark this tag space for release later if
361 * the swapped in page was the last user of tag space
362 */
363 del_tag_store(tag_desc, mm);
364 }
365
366 /* A page is about to be swapped out. Save any ADI tags associated with
367 * this physical page so they can be restored later when the page is swapped
368 * back in.
369 */
370 int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
371 unsigned long addr, pte_t oldpte)
372 {
373 unsigned char *tag;
374 tag_storage_desc_t *tag_desc;
375 unsigned long version1, version2, paddr, tmp;
376
377 tag_desc = alloc_tag_store(mm, vma, addr);
378 if (tag_desc == NULL)
379 return -1;
380
381 tag = tag_start(addr, tag_desc);
382 paddr = pte_val(oldpte) & _PAGE_PADDR_4V;
383 for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
384 asm volatile("ldxa [%1] %2, %0\n\t"
385 : "=r" (version1)
386 : "r" (tmp), "i" (ASI_MCD_REAL));
387 tmp += adi_blksize();
388 asm volatile("ldxa [%1] %2, %0\n\t"
389 : "=r" (version2)
390 : "r" (tmp), "i" (ASI_MCD_REAL));
391 *tag = (version1 << 4) | version2;
392 tag++;
393 }
394
395 return 0;
396 }