aboutsummaryrefslogtreecommitdiffstats
path: root/arch/s390/mm/pgtable.c
blob: 0767827540b1778b0d88fa555d957ca457dc1d41 (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
/*
 *  arch/s390/mm/pgtable.c
 *
 *    Copyright IBM Corp. 2007
 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/quicklist.h>

#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>

#ifndef CONFIG_64BIT
#define ALLOC_ORDER	1
#define TABLES_PER_PAGE	4
#define FRAG_MASK	15UL
#define SECOND_HALVES	10UL

void clear_table_pgstes(unsigned long *table)
{
	clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/4);
	memset(table + 256, 0, PAGE_SIZE/4);
	clear_table(table + 512, _PAGE_TYPE_EMPTY, PAGE_SIZE/4);
	memset(table + 768, 0, PAGE_SIZE/4);
}

#else
#define ALLOC_ORDER	2
#define TABLES_PER_PAGE	2
#define FRAG_MASK	3UL
#define SECOND_HALVES	2UL

void clear_table_pgstes(unsigned long *table)
{
	clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE/2);
	memset(table + 256, 0, PAGE_SIZE/2);
}

#endif

unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec)
{
	struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER);

	if (!page)
		return NULL;
	page->index = 0;
	if (noexec) {
		struct page *shadow = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
		if (!shadow) {
			__free_pages(page, ALLOC_ORDER);
			return NULL;
		}
		page->index = page_to_phys(shadow);
	}
	spin_lock(&mm->page_table_lock);
	list_add(&page->lru, &mm->context.crst_list);
	spin_unlock(&mm->page_table_lock);
	return (unsigned long *) page_to_phys(page);
}

void crst_table_free(struct mm_struct *mm, unsigned long *table)
{
	unsigned long *shadow = get_shadow_table(table);
	struct page *page = virt_to_page(table);

	spin_lock(&mm->page_table_lock);
	list_del(&page->lru);
	spin_unlock(&mm->page_table_lock);
	if (shadow)
		free_pages((unsigned long) shadow, ALLOC_ORDER);
	free_pages((unsigned long) table, ALLOC_ORDER);
}

#ifdef CONFIG_64BIT
int crst_table_upgrade(struct mm_struct *mm, unsigned long limit)
{
	unsigned long *table, *pgd;
	unsigned long entry;

	BUG_ON(limit > (1UL << 53));
repeat:
	table = crst_table_alloc(mm, mm->context.noexec);
	if (!table)
		return -ENOMEM;
	spin_lock(&mm->page_table_lock);
	if (mm->context.asce_limit < limit) {
		pgd = (unsigned long *) mm->pgd;
		if (mm->context.asce_limit <= (1UL << 31)) {
			entry = _REGION3_ENTRY_EMPTY;
			mm->context.asce_limit = 1UL << 42;
			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
						_ASCE_USER_BITS |
						_ASCE_TYPE_REGION3;
		} else {
			entry = _REGION2_ENTRY_EMPTY;
			mm->context.asce_limit = 1UL << 53;
			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
						_ASCE_USER_BITS |
						_ASCE_TYPE_REGION2;
		}
		crst_table_init(table, entry);
		pgd_populate(mm, (pgd_t *) table, (pud_t *) pgd);
		mm->pgd = (pgd_t *) table;
		table = NULL;
	}
	spin_unlock(&mm->page_table_lock);
	if (table)
		crst_table_free(mm, table);
	if (mm->context.asce_limit < limit)
		goto repeat;
	update_mm(mm, current);
	return 0;
}

void crst_table_downgrade(struct mm_struct *mm, unsigned long limit)
{
	pgd_t *pgd;

	if (mm->context.asce_limit <= limit)
		return;
	__tlb_flush_mm(mm);
	while (mm->context.asce_limit > limit) {
		pgd = mm->pgd;
		switch (pgd_val(*pgd) & _REGION_ENTRY_TYPE_MASK) {
		case _REGION_ENTRY_TYPE_R2:
			mm->context.asce_limit = 1UL << 42;
			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
						_ASCE_USER_BITS |
						_ASCE_TYPE_REGION3;
			break;
		case _REGION_ENTRY_TYPE_R3:
			mm->context.asce_limit = 1UL << 31;
			mm->context.asce_bits = _ASCE_TABLE_LENGTH |
						_ASCE_USER_BITS |
						_ASCE_TYPE_SEGMENT;
			break;
		default:
			BUG();
		}
		mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
		crst_table_free(mm, (unsigned long *) pgd);
	}
	update_mm(mm, current);
}
#endif

/*
 * page table entry allocation/free routines.
 */
unsigned long *page_table_alloc(struct mm_struct *mm)
{
	struct page *page;
	unsigned long *table;
	unsigned long bits;

	bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
	spin_lock(&mm->page_table_lock);
	page = NULL;
	if (!list_empty(&mm->context.pgtable_list)) {
		page = list_first_entry(&mm->context.pgtable_list,
					struct page, lru);
		if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
			page = NULL;
	}
	if (!page) {
		spin_unlock(&mm->page_table_lock);
		page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
		if (!page)
			return NULL;
		pgtable_page_ctor(page);
		page->flags &= ~FRAG_MASK;
		table = (unsigned long *) page_to_phys(page);
		if (mm->context.has_pgste)
			clear_table_pgstes(table);
		else
			clear_table(table, _PAGE_TYPE_EMPTY, PAGE_SIZE);
		spin_lock(&mm->page_table_lock);
		list_add(&page->lru, &mm->context.pgtable_list);
	}
	table = (unsigned long *) page_to_phys(page);
	while (page->flags & bits) {
		table += 256;
		bits <<= 1;
	}
	page->flags |= bits;
	if ((page->flags & FRAG_MASK) == ((1UL << TABLES_PER_PAGE) - 1))
		list_move_tail(&page->lru, &mm->context.pgtable_list);
	spin_unlock(&mm->page_table_lock);
	return table;
}

void page_table_free(struct mm_struct *mm, unsigned long *table)
{
	struct page *page;
	unsigned long bits;

	bits = (mm->context.noexec || mm->context.has_pgste) ? 3UL : 1UL;
	bits <<= (__pa(table) & (PAGE_SIZE - 1)) / 256 / sizeof(unsigned long);
	page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
	spin_lock(&mm->page_table_lock);
	page->flags ^= bits;
	if (page->flags & FRAG_MASK) {
		/* Page now has some free pgtable fragments. */
		list_move(&page->lru, &mm->context.pgtable_list);
		page = NULL;
	} else
		/* All fragments of the 4K page have been freed. */
		list_del(&page->lru);
	spin_unlock(&mm->page_table_lock);
	if (page) {
		pgtable_page_dtor(page);
		__free_page(page);
	}
}

void disable_noexec(struct mm_struct *mm, struct task_struct *tsk)
{
	struct page *page;

	spin_lock(&mm->page_table_lock);
	/* Free shadow region and segment tables. */
	list_for_each_entry(page, &mm->context.crst_list, lru)
		if (page->index) {
			free_pages((unsigned long) page->index, ALLOC_ORDER);
			page->index = 0;
		}
	/* "Free" second halves of page tables. */
	list_for_each_entry(page, &mm->context.pgtable_list, lru)
		page->flags &= ~SECOND_HALVES;
	spin_unlock(&mm->page_table_lock);
	mm->context.noexec = 0;
	update_mm(mm, tsk);
}

/*
 * switch on pgstes for its userspace process (for kvm)
 */
int s390_enable_sie(void)
{
	struct task_struct *tsk = current;
	struct mm_struct *mm, *old_mm;

	/* Do we have pgstes? if yes, we are done */
	if (tsk->mm->context.has_pgste)
		return 0;

	/* lets check if we are allowed to replace the mm */
	task_lock(tsk);
	if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
	    tsk->mm != tsk->active_mm || !hlist_empty(&tsk->mm->ioctx_list)) {
		task_unlock(tsk);
		return -EINVAL;
	}
	task_unlock(tsk);

	/* we copy the mm and let dup_mm create the page tables with_pgstes */
	tsk->mm->context.alloc_pgste = 1;
	mm = dup_mm(tsk);
	tsk->mm->context.alloc_pgste = 0;
	if (!mm)
		return -ENOMEM;

	/* Now lets check again if something happened */
	task_lock(tsk);
	if (!tsk->mm || atomic_read(&tsk->mm->mm_users) > 1 ||
	    tsk->mm != tsk->active_mm || !hlist_empty(&tsk->mm->ioctx_list)) {
		mmput(mm);
		task_unlock(tsk);
		return -EINVAL;
	}

	/* ok, we are alone. No ptrace, no threads, etc. */
	old_mm = tsk->mm;
	tsk->mm = tsk->active_mm = mm;
	preempt_disable();
	update_mm(mm, tsk);
	cpu_set(smp_processor_id(), mm->cpu_vm_mask);
	preempt_enable();
	task_unlock(tsk);
	mmput(old_mm);
	return 0;
}
EXPORT_SYMBOL_GPL(s390_enable_sie);