aboutsummaryrefslogtreecommitdiff
path: root/arch/s390/lib/uaccess_pt.c
blob: 60604b2819b2a0d07c4664860ecb4c462ee92ee1 (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
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
/*
 *  arch/s390/lib/uaccess_pt.c
 *
 *  User access functions based on page table walks for enhanced
 *  system layout without hardware support.
 *
 *    Copyright IBM Corp. 2006
 *    Author(s): Gerald Schaefer (gerald.schaefer@de.ibm.com)
 */

#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/mm.h>
#include <asm/uaccess.h>
#include <asm/futex.h>
#include "uaccess.h"

static int __handle_fault(struct mm_struct *mm, unsigned long address,
			  int write_access)
{
	struct vm_area_struct *vma;
	int ret = -EFAULT;
	int fault;

	if (in_atomic())
		return ret;
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, address);
	if (unlikely(!vma))
		goto out;
	if (unlikely(vma->vm_start > address)) {
		if (!(vma->vm_flags & VM_GROWSDOWN))
			goto out;
		if (expand_stack(vma, address))
			goto out;
	}

	if (!write_access) {
		/* page not present, check vm flags */
		if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
			goto out;
	} else {
		if (!(vma->vm_flags & VM_WRITE))
			goto out;
	}

survive:
	fault = handle_mm_fault(mm, vma, address, write_access);
	if (unlikely(fault & VM_FAULT_ERROR)) {
		if (fault & VM_FAULT_OOM)
			goto out_of_memory;
		else if (fault & VM_FAULT_SIGBUS)
			goto out_sigbus;
		BUG();
	}
	if (fault & VM_FAULT_MAJOR)
		current->maj_flt++;
	else
		current->min_flt++;
	ret = 0;
out:
	up_read(&mm->mmap_sem);
	return ret;

out_of_memory:
	up_read(&mm->mmap_sem);
	if (is_init(current)) {
		yield();
		down_read(&mm->mmap_sem);
		goto survive;
	}
	printk("VM: killing process %s\n", current->comm);
	return ret;

out_sigbus:
	up_read(&mm->mmap_sem);
	current->thread.prot_addr = address;
	current->thread.trap_no = 0x11;
	force_sig(SIGBUS, current);
	return ret;
}

static size_t __user_copy_pt(unsigned long uaddr, void *kptr,
			     size_t n, int write_user)
{
	struct mm_struct *mm = current->mm;
	unsigned long offset, pfn, done, size;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	void *from, *to;

	done = 0;
retry:
	spin_lock(&mm->page_table_lock);
	do {
		pgd = pgd_offset(mm, uaddr);
		if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
			goto fault;

		pmd = pmd_offset(pgd, uaddr);
		if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
			goto fault;

		pte = pte_offset_map(pmd, uaddr);
		if (!pte || !pte_present(*pte) ||
		    (write_user && !pte_write(*pte)))
			goto fault;

		pfn = pte_pfn(*pte);
		if (!pfn_valid(pfn))
			goto out;

		offset = uaddr & (PAGE_SIZE - 1);
		size = min(n - done, PAGE_SIZE - offset);
		if (write_user) {
			to = (void *)((pfn << PAGE_SHIFT) + offset);
			from = kptr + done;
		} else {
			from = (void *)((pfn << PAGE_SHIFT) + offset);
			to = kptr + done;
		}
		memcpy(to, from, size);
		done += size;
		uaddr += size;
	} while (done < n);
out:
	spin_unlock(&mm->page_table_lock);
	return n - done;
fault:
	spin_unlock(&mm->page_table_lock);
	if (__handle_fault(mm, uaddr, write_user))
		return n - done;
	goto retry;
}

/*
 * Do DAT for user address by page table walk, return kernel address.
 * This function needs to be called with current->mm->page_table_lock held.
 */
static unsigned long __dat_user_addr(unsigned long uaddr)
{
	struct mm_struct *mm = current->mm;
	unsigned long pfn, ret;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	int rc;

	ret = 0;
retry:
	pgd = pgd_offset(mm, uaddr);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
		goto fault;

	pmd = pmd_offset(pgd, uaddr);
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
		goto fault;

	pte = pte_offset_map(pmd, uaddr);
	if (!pte || !pte_present(*pte))
		goto fault;

	pfn = pte_pfn(*pte);
	if (!pfn_valid(pfn))
		goto out;

	ret = (pfn << PAGE_SHIFT) + (uaddr & (PAGE_SIZE - 1));
out:
	return ret;
fault:
	spin_unlock(&mm->page_table_lock);
	rc = __handle_fault(mm, uaddr, 0);
	spin_lock(&mm->page_table_lock);
	if (rc)
		goto out;
	goto retry;
}

size_t copy_from_user_pt(size_t n, const void __user *from, void *to)
{
	size_t rc;

	if (segment_eq(get_fs(), KERNEL_DS)) {
		memcpy(to, (void __kernel __force *) from, n);
		return 0;
	}
	rc = __user_copy_pt((unsigned long) from, to, n, 0);
	if (unlikely(rc))
		memset(to + n - rc, 0, rc);
	return rc;
}

size_t copy_to_user_pt(size_t n, void __user *to, const void *from)
{
	if (segment_eq(get_fs(), KERNEL_DS)) {
		memcpy((void __kernel __force *) to, from, n);
		return 0;
	}
	return __user_copy_pt((unsigned long) to, (void *) from, n, 1);
}

static size_t clear_user_pt(size_t n, void __user *to)
{
	long done, size, ret;

	if (segment_eq(get_fs(), KERNEL_DS)) {
		memset((void __kernel __force *) to, 0, n);
		return 0;
	}
	done = 0;
	do {
		if (n - done > PAGE_SIZE)
			size = PAGE_SIZE;
		else
			size = n - done;
		ret = __user_copy_pt((unsigned long) to + done,
				      &empty_zero_page, size, 1);
		done += size;
		if (ret)
			return ret + n - done;
	} while (done < n);
	return 0;
}

static size_t strnlen_user_pt(size_t count, const char __user *src)
{
	char *addr;
	unsigned long uaddr = (unsigned long) src;
	struct mm_struct *mm = current->mm;
	unsigned long offset, pfn, done, len;
	pgd_t *pgd;
	pmd_t *pmd;
	pte_t *pte;
	size_t len_str;

	if (segment_eq(get_fs(), KERNEL_DS))
		return strnlen((const char __kernel __force *) src, count) + 1;
	done = 0;
retry:
	spin_lock(&mm->page_table_lock);
	do {
		pgd = pgd_offset(mm, uaddr);
		if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
			goto fault;

		pmd = pmd_offset(pgd, uaddr);
		if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
			goto fault;

		pte = pte_offset_map(pmd, uaddr);
		if (!pte || !pte_present(*pte))
			goto fault;

		pfn = pte_pfn(*pte);
		if (!pfn_valid(pfn)) {
			done = -1;
			goto out;
		}

		offset = uaddr & (PAGE_SIZE-1);
		addr = (char *)(pfn << PAGE_SHIFT) + offset;
		len = min(count - done, PAGE_SIZE - offset);
		len_str = strnlen(addr, len);
		done += len_str;
		uaddr += len_str;
	} while ((len_str == len) && (done < count));
out:
	spin_unlock(&mm->page_table_lock);
	return done + 1;
fault:
	spin_unlock(&mm->page_table_lock);
	if (__handle_fault(mm, uaddr, 0)) {
		return 0;
	}
	goto retry;
}

static size_t strncpy_from_user_pt(size_t count, const char __user *src,
				   char *dst)
{
	size_t n = strnlen_user_pt(count, src);

	if (!n)
		return -EFAULT;
	if (n > count)
		n = count;
	if (segment_eq(get_fs(), KERNEL_DS)) {
		memcpy(dst, (const char __kernel __force *) src, n);
		if (dst[n-1] == '\0')
			return n-1;
		else
			return n;
	}
	if (__user_copy_pt((unsigned long) src, dst, n, 0))
		return -EFAULT;
	if (dst[n-1] == '\0')
		return n-1;
	else
		return n;
}

static size_t copy_in_user_pt(size_t n, void __user *to,
			      const void __user *from)
{
	struct mm_struct *mm = current->mm;
	unsigned long offset_from, offset_to, offset_max, pfn_from, pfn_to,
		      uaddr, done, size;
	unsigned long uaddr_from = (unsigned long) from;
	unsigned long uaddr_to = (unsigned long) to;
	pgd_t *pgd_from, *pgd_to;
	pmd_t *pmd_from, *pmd_to;
	pte_t *pte_from, *pte_to;
	int write_user;

	done = 0;
retry:
	spin_lock(&mm->page_table_lock);
	do {
		pgd_from = pgd_offset(mm, uaddr_from);
		if (pgd_none(*pgd_from) || unlikely(pgd_bad(*pgd_from))) {
			uaddr = uaddr_from;
			write_user = 0;
			goto fault;
		}
		pgd_to = pgd_offset(mm, uaddr_to);
		if (pgd_none(*pgd_to) || unlikely(pgd_bad(*pgd_to))) {
			uaddr = uaddr_to;
			write_user = 1;
			goto fault;
		}

		pmd_from = pmd_offset(pgd_from, uaddr_from);
		if (pmd_none(*pmd_from) || unlikely(pmd_bad(*pmd_from))) {
			uaddr = uaddr_from;
			write_user = 0;
			goto fault;
		}
		pmd_to = pmd_offset(pgd_to, uaddr_to);
		if (pmd_none(*pmd_to) || unlikely(pmd_bad(*pmd_to))) {
			uaddr = uaddr_to;
			write_user = 1;
			goto fault;
		}

		pte_from = pte_offset_map(pmd_from, uaddr_from);
		if (!pte_from || !pte_present(*pte_from)) {
			uaddr = uaddr_from;
			write_user = 0;
			goto fault;
		}
		pte_to = pte_offset_map(pmd_to, uaddr_to);
		if (!pte_to || !pte_present(*pte_to) || !pte_write(*pte_to)) {
			uaddr = uaddr_to;
			write_user = 1;
			goto fault;
		}

		pfn_from = pte_pfn(*pte_from);
		if (!pfn_valid(pfn_from))
			goto out;
		pfn_to = pte_pfn(*pte_to);
		if (!pfn_valid(pfn_to))
			goto out;

		offset_from = uaddr_from & (PAGE_SIZE-1);
		offset_to = uaddr_from & (PAGE_SIZE-1);
		offset_max = max(offset_from, offset_to);
		size = min(n - done, PAGE_SIZE - offset_max);

		memcpy((void *)(pfn_to << PAGE_SHIFT) + offset_to,
		       (void *)(pfn_from << PAGE_SHIFT) + offset_from, size);
		done += size;
		uaddr_from += size;
		uaddr_to += size;
	} while (done < n);
out:
	spin_unlock(&mm->page_table_lock);
	return n - done;
fault:
	spin_unlock(&mm->page_table_lock);
	if (__handle_fault(mm, uaddr, write_user))
		return n - done;
	goto retry;
}

#define __futex_atomic_op(insn, ret, oldval, newval, uaddr, oparg)	\
	asm volatile("0: l   %1,0(%6)\n"				\
		     "1: " insn						\
		     "2: cs  %1,%2,0(%6)\n"				\
		     "3: jl  1b\n"					\
		     "   lhi %0,0\n"					\
		     "4:\n"						\
		     EX_TABLE(0b,4b) EX_TABLE(2b,4b) EX_TABLE(3b,4b)	\
		     : "=d" (ret), "=&d" (oldval), "=&d" (newval),	\
		       "=m" (*uaddr)					\
		     : "0" (-EFAULT), "d" (oparg), "a" (uaddr),		\
		       "m" (*uaddr) : "cc" );

int futex_atomic_op_pt(int op, int __user *uaddr, int oparg, int *old)
{
	int oldval = 0, newval, ret;

	spin_lock(&current->mm->page_table_lock);
	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
	if (!uaddr) {
		spin_unlock(&current->mm->page_table_lock);
		return -EFAULT;
	}
	get_page(virt_to_page(uaddr));
	spin_unlock(&current->mm->page_table_lock);
	switch (op) {
	case FUTEX_OP_SET:
		__futex_atomic_op("lr %2,%5\n",
				  ret, oldval, newval, uaddr, oparg);
		break;
	case FUTEX_OP_ADD:
		__futex_atomic_op("lr %2,%1\nar %2,%5\n",
				  ret, oldval, newval, uaddr, oparg);
		break;
	case FUTEX_OP_OR:
		__futex_atomic_op("lr %2,%1\nor %2,%5\n",
				  ret, oldval, newval, uaddr, oparg);
		break;
	case FUTEX_OP_ANDN:
		__futex_atomic_op("lr %2,%1\nnr %2,%5\n",
				  ret, oldval, newval, uaddr, oparg);
		break;
	case FUTEX_OP_XOR:
		__futex_atomic_op("lr %2,%1\nxr %2,%5\n",
				  ret, oldval, newval, uaddr, oparg);
		break;
	default:
		ret = -ENOSYS;
	}
	put_page(virt_to_page(uaddr));
	*old = oldval;
	return ret;
}

int futex_atomic_cmpxchg_pt(int __user *uaddr, int oldval, int newval)
{
	int ret;

	spin_lock(&current->mm->page_table_lock);
	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
	if (!uaddr) {
		spin_unlock(&current->mm->page_table_lock);
		return -EFAULT;
	}
	get_page(virt_to_page(uaddr));
	spin_unlock(&current->mm->page_table_lock);
	asm volatile("   cs   %1,%4,0(%5)\n"
		     "0: lr   %0,%1\n"
		     "1:\n"
		     EX_TABLE(0b,1b)
		     : "=d" (ret), "+d" (oldval), "=m" (*uaddr)
		     : "0" (-EFAULT), "d" (newval), "a" (uaddr), "m" (*uaddr)
		     : "cc", "memory" );
	put_page(virt_to_page(uaddr));
	return ret;
}

struct uaccess_ops uaccess_pt = {
	.copy_from_user		= copy_from_user_pt,
	.copy_from_user_small	= copy_from_user_pt,
	.copy_to_user		= copy_to_user_pt,
	.copy_to_user_small	= copy_to_user_pt,
	.copy_in_user		= copy_in_user_pt,
	.clear_user		= clear_user_pt,
	.strnlen_user		= strnlen_user_pt,
	.strncpy_from_user	= strncpy_from_user_pt,
	.futex_atomic_op	= futex_atomic_op_pt,
	.futex_atomic_cmpxchg	= futex_atomic_cmpxchg_pt,
};