summaryrefslogtreecommitdiffstats
path: root/arch/sparc/kernel/adi_64.c
blob: e0e4fc527b24fe912701d4bcd8124491aaa9d256 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
// SPDX-License-Identifier: GPL-2.0-only
/* adi_64.c: support for ADI (Application Data Integrity) feature on
 * sparc m7 and newer processors. This feature is also known as
 * SSM (Silicon Secured Memory).
 *
 * Copyright (C) 2016 Oracle and/or its affiliates. All rights reserved.
 * Author: Khalid Aziz (khalid.aziz@oracle.com)
 */
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/mm_types.h>
#include <asm/mdesc.h>
#include <asm/adi_64.h>
#include <asm/mmu_64.h>
#include <asm/pgtable_64.h>

/* Each page of storage for ADI tags can accommodate tags for 128
 * pages. When ADI enabled pages are being swapped out, it would be
 * prudent to allocate at least enough tag storage space to accommodate
 * SWAPFILE_CLUSTER number of pages. Allocate enough tag storage to
 * store tags for four SWAPFILE_CLUSTER pages to reduce need for
 * further allocations for same vma.
 */
#define TAG_STORAGE_PAGES	8

struct adi_config adi_state;
EXPORT_SYMBOL(adi_state);

/* mdesc_adi_init() : Parse machine description provided by the
 *	hypervisor to detect ADI capabilities
 *
 * Hypervisor reports ADI capabilities of platform in "hwcap-list" property
 * for "cpu" node. If the platform supports ADI, "hwcap-list" property
 * contains the keyword "adp". If the platform supports ADI, "platform"
 * node will contain "adp-blksz", "adp-nbits" and "ue-on-adp" properties
 * to describe the ADI capabilities.
 */
void __init mdesc_adi_init(void)
{
	struct mdesc_handle *hp = mdesc_grab();
	const char *prop;
	u64 pn, *val;
	int len;

	if (!hp)
		goto adi_not_found;

	pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "cpu");
	if (pn == MDESC_NODE_NULL)
		goto adi_not_found;

	prop = mdesc_get_property(hp, pn, "hwcap-list", &len);
	if (!prop)
		goto adi_not_found;

	/*
	 * Look for "adp" keyword in hwcap-list which would indicate
	 * ADI support
	 */
	adi_state.enabled = false;
	while (len) {
		int plen;

		if (!strcmp(prop, "adp")) {
			adi_state.enabled = true;
			break;
		}

		plen = strlen(prop) + 1;
		prop += plen;
		len -= plen;
	}

	if (!adi_state.enabled)
		goto adi_not_found;

	/* Find the ADI properties in "platform" node. If all ADI
	 * properties are not found, ADI support is incomplete and
	 * do not enable ADI in the kernel.
	 */
	pn = mdesc_node_by_name(hp, MDESC_NODE_NULL, "platform");
	if (pn == MDESC_NODE_NULL)
		goto adi_not_found;

	val = (u64 *) mdesc_get_property(hp, pn, "adp-blksz", &len);
	if (!val)
		goto adi_not_found;
	adi_state.caps.blksz = *val;

	val = (u64 *) mdesc_get_property(hp, pn, "adp-nbits", &len);
	if (!val)
		goto adi_not_found;
	adi_state.caps.nbits = *val;

	val = (u64 *) mdesc_get_property(hp, pn, "ue-on-adp", &len);
	if (!val)
		goto adi_not_found;
	adi_state.caps.ue_on_adi = *val;

	/* Some of the code to support swapping ADI tags is written
	 * assumption that two ADI tags can fit inside one byte. If
	 * this assumption is broken by a future architecture change,
	 * that code will have to be revisited. If that were to happen,
	 * disable ADI support so we do not get unpredictable results
	 * with programs trying to use ADI and their pages getting
	 * swapped out
	 */
	if (adi_state.caps.nbits > 4) {
		pr_warn("WARNING: ADI tag size >4 on this platform. Disabling AADI support\n");
		adi_state.enabled = false;
	}

	mdesc_release(hp);
	return;

adi_not_found:
	adi_state.enabled = false;
	adi_state.caps.blksz = 0;
	adi_state.caps.nbits = 0;
	if (hp)
		mdesc_release(hp);
}

static tag_storage_desc_t *find_tag_store(struct mm_struct *mm,
					  struct vm_area_struct *vma,
					  unsigned long addr)
{
	tag_storage_desc_t *tag_desc = NULL;
	unsigned long i, max_desc, flags;

	/* Check if this vma already has tag storage descriptor
	 * allocated for it.
	 */
	max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
	if (mm->context.tag_store) {
		tag_desc = mm->context.tag_store;
		spin_lock_irqsave(&mm->context.tag_lock, flags);
		for (i = 0; i < max_desc; i++) {
			if ((addr >= tag_desc->start) &&
			    ((addr + PAGE_SIZE - 1) <= tag_desc->end))
				break;
			tag_desc++;
		}
		spin_unlock_irqrestore(&mm->context.tag_lock, flags);

		/* If no matching entries were found, this must be a
		 * freshly allocated page
		 */
		if (i >= max_desc)
			tag_desc = NULL;
	}

	return tag_desc;
}

static tag_storage_desc_t *alloc_tag_store(struct mm_struct *mm,
					   struct vm_area_struct *vma,
					   unsigned long addr)
{
	unsigned char *tags;
	unsigned long i, size, max_desc, flags;
	tag_storage_desc_t *tag_desc, *open_desc;
	unsigned long end_addr, hole_start, hole_end;

	max_desc = PAGE_SIZE/sizeof(tag_storage_desc_t);
	open_desc = NULL;
	hole_start = 0;
	hole_end = ULONG_MAX;
	end_addr = addr + PAGE_SIZE - 1;

	/* Check if this vma already has tag storage descriptor
	 * allocated for it.
	 */
	spin_lock_irqsave(&mm->context.tag_lock, flags);
	if (mm->context.tag_store) {
		tag_desc = mm->context.tag_store;

		/* Look for a matching entry for this address. While doing
		 * that, look for the first open slot as well and find
		 * the hole in already allocated range where this request
		 * will fit in.
		 */
		for (i = 0; i < max_desc; i++) {
			if (tag_desc->tag_users == 0) {
				if (open_desc == NULL)
					open_desc = tag_desc;
			} else {
				if ((addr >= tag_desc->start) &&
				    (tag_desc->end >= (addr + PAGE_SIZE - 1))) {
					tag_desc->tag_users++;
					goto out;
				}
			}
			if ((tag_desc->start > end_addr) &&
			    (tag_desc->start < hole_end))
				hole_end = tag_desc->start;
			if ((tag_desc->end < addr) &&
			    (tag_desc->end > hole_start))
				hole_start = tag_desc->end;
			tag_desc++;
		}

	} else {
		size = sizeof(tag_storage_desc_t)*max_desc;
		mm->context.tag_store = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
		if (mm->context.tag_store == NULL) {
			tag_desc = NULL;
			goto out;
		}
		tag_desc = mm->context.tag_store;
		for (i = 0; i < max_desc; i++, tag_desc++)
			tag_desc->tag_users = 0;
		open_desc = mm->context.tag_store;
		i = 0;
	}

	/* Check if we ran out of tag storage descriptors */
	if (open_desc == NULL) {
		tag_desc = NULL;
		goto out;
	}

	/* Mark this tag descriptor slot in use and then initialize it */
	tag_desc = open_desc;
	tag_desc->tag_users = 1;

	/* Tag storage has not been allocated for this vma and space
	 * is available in tag storage descriptor. Since this page is
	 * being swapped out, there is high probability subsequent pages
	 * in the VMA will be swapped out as well. Allocate pages to
	 * store tags for as many pages in this vma as possible but not
	 * more than TAG_STORAGE_PAGES. Each byte in tag space holds
	 * two ADI tags since each ADI tag is 4 bits. Each ADI tag
	 * covers adi_blksize() worth of addresses. Check if the hole is
	 * big enough to accommodate full address range for using
	 * TAG_STORAGE_PAGES number of tag pages.
	 */
	size = TAG_STORAGE_PAGES * PAGE_SIZE;
	end_addr = addr + (size*2*adi_blksize()) - 1;
	/* Check for overflow. If overflow occurs, allocate only one page */
	if (end_addr < addr) {
		size = PAGE_SIZE;
		end_addr = addr + (size*2*adi_blksize()) - 1;
		/* If overflow happens with the minimum tag storage
		 * allocation as well, adjust ending address for this
		 * tag storage.
		 */
		if (end_addr < addr)
			end_addr = ULONG_MAX;
	}
	if (hole_end < end_addr) {
		/* Available hole is too small on the upper end of
		 * address. Can we expand the range towards the lower
		 * address and maximize use of this slot?
		 */
		unsigned long tmp_addr;

		end_addr = hole_end - 1;
		tmp_addr = end_addr - (size*2*adi_blksize()) + 1;
		/* Check for underflow. If underflow occurs, allocate
		 * only one page for storing ADI tags
		 */
		if (tmp_addr > addr) {
			size = PAGE_SIZE;
			tmp_addr = end_addr - (size*2*adi_blksize()) - 1;
			/* If underflow happens with the minimum tag storage
			 * allocation as well, adjust starting address for
			 * this tag storage.
			 */
			if (tmp_addr > addr)
				tmp_addr = 0;
		}
		if (tmp_addr < hole_start) {
			/* Available hole is restricted on lower address
			 * end as well
			 */
			tmp_addr = hole_start + 1;
		}
		addr = tmp_addr;
		size = (end_addr + 1 - addr)/(2*adi_blksize());
		size = (size + (PAGE_SIZE-adi_blksize()))/PAGE_SIZE;
		size = size * PAGE_SIZE;
	}
	tags = kzalloc(size, GFP_NOWAIT|__GFP_NOWARN);
	if (tags == NULL) {
		tag_desc->tag_users = 0;
		tag_desc = NULL;
		goto out;
	}
	tag_desc->start = addr;
	tag_desc->tags = tags;
	tag_desc->end = end_addr;

out:
	spin_unlock_irqrestore(&mm->context.tag_lock, flags);
	return tag_desc;
}

static void del_tag_store(tag_storage_desc_t *tag_desc, struct mm_struct *mm)
{
	unsigned long flags;
	unsigned char *tags = NULL;

	spin_lock_irqsave(&mm->context.tag_lock, flags);
	tag_desc->tag_users--;
	if (tag_desc->tag_users == 0) {
		tag_desc->start = tag_desc->end = 0;
		/* Do not free up the tag storage space allocated
		 * by the first descriptor. This is persistent
		 * emergency tag storage space for the task.
		 */
		if (tag_desc != mm->context.tag_store) {
			tags = tag_desc->tags;
			tag_desc->tags = NULL;
		}
	}
	spin_unlock_irqrestore(&mm->context.tag_lock, flags);
	kfree(tags);
}

#define tag_start(addr, tag_desc)		\
	((tag_desc)->tags + ((addr - (tag_desc)->start)/(2*adi_blksize())))

/* Retrieve any saved ADI tags for the page being swapped back in and
 * restore these tags to the newly allocated physical page.
 */
void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
		      unsigned long addr, pte_t pte)
{
	unsigned char *tag;
	tag_storage_desc_t *tag_desc;
	unsigned long paddr, tmp, version1, version2;

	/* Check if the swapped out page has an ADI version
	 * saved. If yes, restore version tag to the newly
	 * allocated page.
	 */
	tag_desc = find_tag_store(mm, vma, addr);
	if (tag_desc == NULL)
		return;

	tag = tag_start(addr, tag_desc);
	paddr = pte_val(pte) & _PAGE_PADDR_4V;
	for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
		version1 = (*tag) >> 4;
		version2 = (*tag) & 0x0f;
		*tag++ = 0;
		asm volatile("stxa %0, [%1] %2\n\t"
			:
			: "r" (version1), "r" (tmp),
			  "i" (ASI_MCD_REAL));
		tmp += adi_blksize();
		asm volatile("stxa %0, [%1] %2\n\t"
			:
			: "r" (version2), "r" (tmp),
			  "i" (ASI_MCD_REAL));
	}
	asm volatile("membar #Sync\n\t");

	/* Check and mark this tag space for release later if
	 * the swapped in page was the last user of tag space
	 */
	del_tag_store(tag_desc, mm);
}

/* A page is about to be swapped out. Save any ADI tags associated with
 * this physical page so they can be restored later when the page is swapped
 * back in.
 */
int adi_save_tags(struct mm_struct *mm, struct vm_area_struct *vma,
		  unsigned long addr, pte_t oldpte)
{
	unsigned char *tag;
	tag_storage_desc_t *tag_desc;
	unsigned long version1, version2, paddr, tmp;

	tag_desc = alloc_tag_store(mm, vma, addr);
	if (tag_desc == NULL)
		return -1;

	tag = tag_start(addr, tag_desc);
	paddr = pte_val(oldpte) & _PAGE_PADDR_4V;
	for (tmp = paddr; tmp < (paddr+PAGE_SIZE); tmp += adi_blksize()) {
		asm volatile("ldxa [%1] %2, %0\n\t"
				: "=r" (version1)
				: "r" (tmp), "i" (ASI_MCD_REAL));
		tmp += adi_blksize();
		asm volatile("ldxa [%1] %2, %0\n\t"
				: "=r" (version2)
				: "r" (tmp), "i" (ASI_MCD_REAL));
		*tag = (version1 << 4) | version2;
		tag++;
	}

	return 0;
}