1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <linux/err.h>
7#include <linux/highmem.h>
8#include <linux/mm.h>
9#include <linux/module.h>
10#include <linux/sched.h>
11#include <asm/current.h>
12#include <asm/page.h>
13#include <kern_util.h>
14#include <asm/futex.h>
15#include <os.h>
16
17pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
18{
19	pgd_t *pgd;
20	p4d_t *p4d;
21	pud_t *pud;
22	pmd_t *pmd;
23
24	if (mm == NULL)
25		return NULL;
26
27	pgd = pgd_offset(mm, addr);
28	if (!pgd_present(*pgd))
29		return NULL;
30
31	p4d = p4d_offset(pgd, addr);
32	if (!p4d_present(*p4d))
33		return NULL;
34
35	pud = pud_offset(p4d, addr);
36	if (!pud_present(*pud))
37		return NULL;
38
39	pmd = pmd_offset(pud, addr);
40	if (!pmd_present(*pmd))
41		return NULL;
42
43	return pte_offset_kernel(pmd, addr);
44}
45
46static pte_t *maybe_map(unsigned long virt, int is_write)
47{
48	pte_t *pte = virt_to_pte(current->mm, virt);
49	int err, dummy_code;
50
51	if ((pte == NULL) || !pte_present(*pte) ||
52	    (is_write && !pte_write(*pte))) {
53		err = handle_page_fault(virt, 0, is_write, 1, &dummy_code);
54		if (err)
55			return NULL;
56		pte = virt_to_pte(current->mm, virt);
57	}
58	if (!pte_present(*pte))
59		pte = NULL;
60
61	return pte;
62}
63
64static int do_op_one_page(unsigned long addr, int len, int is_write,
65		 int (*op)(unsigned long addr, int len, void *arg), void *arg)
66{
67	struct page *page;
68	pte_t *pte;
69	int n;
70
71	pte = maybe_map(addr, is_write);
72	if (pte == NULL)
73		return -1;
74
75	page = pte_page(*pte);
76#ifdef CONFIG_64BIT
77	pagefault_disable();
78	addr = (unsigned long) page_address(page) +
79		(addr & ~PAGE_MASK);
80#else
81	addr = (unsigned long) kmap_atomic(page) +
82		(addr & ~PAGE_MASK);
83#endif
84	n = (*op)(addr, len, arg);
85
86#ifdef CONFIG_64BIT
87	pagefault_enable();
88#else
89	kunmap_atomic((void *)addr);
90#endif
91
92	return n;
93}
94
95static long buffer_op(unsigned long addr, int len, int is_write,
96		      int (*op)(unsigned long, int, void *), void *arg)
97{
98	long size, remain, n;
99
100	size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
101	remain = len;
102
103	n = do_op_one_page(addr, size, is_write, op, arg);
104	if (n != 0) {
105		remain = (n < 0 ? remain : 0);
106		goto out;
107	}
108
109	addr += size;
110	remain -= size;
111	if (remain == 0)
112		goto out;
113
114	while (addr < ((addr + remain) & PAGE_MASK)) {
115		n = do_op_one_page(addr, PAGE_SIZE, is_write, op, arg);
116		if (n != 0) {
117			remain = (n < 0 ? remain : 0);
118			goto out;
119		}
120
121		addr += PAGE_SIZE;
122		remain -= PAGE_SIZE;
123	}
124	if (remain == 0)
125		goto out;
126
127	n = do_op_one_page(addr, remain, is_write, op, arg);
128	if (n != 0) {
129		remain = (n < 0 ? remain : 0);
130		goto out;
131	}
132
133	return 0;
134 out:
135	return remain;
136}
137
138static int copy_chunk_from_user(unsigned long from, int len, void *arg)
139{
140	unsigned long *to_ptr = arg, to = *to_ptr;
141
142	memcpy((void *) to, (void *) from, len);
143	*to_ptr += len;
144	return 0;
145}
146
147unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long n)
148{
149	return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to);
150}
151EXPORT_SYMBOL(raw_copy_from_user);
152
153static int copy_chunk_to_user(unsigned long to, int len, void *arg)
154{
155	unsigned long *from_ptr = arg, from = *from_ptr;
156
157	memcpy((void *) to, (void *) from, len);
158	*from_ptr += len;
159	return 0;
160}
161
162unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long n)
163{
164	return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from);
165}
166EXPORT_SYMBOL(raw_copy_to_user);
167
168static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
169{
170	char **to_ptr = arg, *to = *to_ptr;
171	int n;
172
173	strncpy(to, (void *) from, len);
174	n = strnlen(to, len);
175	*to_ptr += n;
176
177	if (n < len)
178	        return 1;
179	return 0;
180}
181
182long strncpy_from_user(char *dst, const char __user *src, long count)
183{
184	long n;
185	char *ptr = dst;
186
187	if (!access_ok(src, 1))
188		return -EFAULT;
189	n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
190		      &ptr);
191	if (n != 0)
192		return -EFAULT;
193	return strnlen(dst, count);
194}
195EXPORT_SYMBOL(strncpy_from_user);
196
197static int clear_chunk(unsigned long addr, int len, void *unused)
198{
199	memset((void *) addr, 0, len);
200	return 0;
201}
202
203unsigned long __clear_user(void __user *mem, unsigned long len)
204{
205	return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
206}
207EXPORT_SYMBOL(__clear_user);
208
209static int strnlen_chunk(unsigned long str, int len, void *arg)
210{
211	int *len_ptr = arg, n;
212
213	n = strnlen((void *) str, len);
214	*len_ptr += n;
215
216	if (n < len)
217		return 1;
218	return 0;
219}
220
221long strnlen_user(const char __user *str, long len)
222{
223	int count = 0, n;
224
225	if (!access_ok(str, 1))
226		return -EFAULT;
227	n = buffer_op((unsigned long) str, len, 0, strnlen_chunk, &count);
228	if (n == 0)
229		return count + 1;
230	return 0;
231}
232EXPORT_SYMBOL(strnlen_user);
233
234/**
235 * arch_futex_atomic_op_inuser() - Atomic arithmetic operation with constant
236 *			  argument and comparison of the previous
237 *			  futex value with another constant.
238 *
239 * @op:		operation to execute
240 * @oparg:	argument to operation
241 * @oval:	old value at uaddr
242 * @uaddr:	pointer to user space address
243 *
244 * Return:
245 * 0 - On success
246 * -EFAULT - User access resulted in a page fault
247 * -EAGAIN - Atomic operation was unable to complete due to contention
248 * -ENOSYS - Operation not supported
249 */
250
251int arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
252{
253	int oldval, ret;
254	struct page *page;
255	unsigned long addr = (unsigned long) uaddr;
256	pte_t *pte;
257
258	ret = -EFAULT;
259	if (!access_ok(uaddr, sizeof(*uaddr)))
260		return -EFAULT;
261	preempt_disable();
262	pte = maybe_map(addr, 1);
263	if (pte == NULL)
264		goto out_inuser;
265
266	page = pte_page(*pte);
267#ifdef CONFIG_64BIT
268	pagefault_disable();
269	addr = (unsigned long) page_address(page) +
270			(((unsigned long) addr) & ~PAGE_MASK);
271#else
272	addr = (unsigned long) kmap_atomic(page) +
273		((unsigned long) addr & ~PAGE_MASK);
274#endif
275	uaddr = (u32 *) addr;
276	oldval = *uaddr;
277
278	ret = 0;
279
280	switch (op) {
281	case FUTEX_OP_SET:
282		*uaddr = oparg;
283		break;
284	case FUTEX_OP_ADD:
285		*uaddr += oparg;
286		break;
287	case FUTEX_OP_OR:
288		*uaddr |= oparg;
289		break;
290	case FUTEX_OP_ANDN:
291		*uaddr &= ~oparg;
292		break;
293	case FUTEX_OP_XOR:
294		*uaddr ^= oparg;
295		break;
296	default:
297		ret = -ENOSYS;
298	}
299#ifdef CONFIG_64BIT
300	pagefault_enable();
301#else
302	kunmap_atomic((void *)addr);
303#endif
304
305out_inuser:
306	preempt_enable();
307
308	if (ret == 0)
309		*oval = oldval;
310
311	return ret;
312}
313EXPORT_SYMBOL(arch_futex_atomic_op_inuser);
314
315/**
316 * futex_atomic_cmpxchg_inatomic() - Compare and exchange the content of the
317 *				uaddr with newval if the current value is
318 *				oldval.
319 * @uval:	pointer to store content of @uaddr
320 * @uaddr:	pointer to user space address
321 * @oldval:	old value
322 * @newval:	new value to store to @uaddr
323 *
324 * Return:
325 * 0 - On success
326 * -EFAULT - User access resulted in a page fault
327 * -EAGAIN - Atomic operation was unable to complete due to contention
328 */
329
330int futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
331			      u32 oldval, u32 newval)
332{
333	struct page *page;
334	pte_t *pte;
335	int ret = -EFAULT;
336
337	if (!access_ok(uaddr, sizeof(*uaddr)))
338		return -EFAULT;
339
340	preempt_disable();
341	pte = maybe_map((unsigned long) uaddr, 1);
342	if (pte == NULL)
343		goto out_inatomic;
344
345	page = pte_page(*pte);
346#ifdef CONFIG_64BIT
347	pagefault_disable();
348	uaddr = page_address(page) + (((unsigned long) uaddr) & ~PAGE_MASK);
349#else
350	uaddr = kmap_atomic(page) + ((unsigned long) uaddr & ~PAGE_MASK);
351#endif
352
353	*uval = *uaddr;
354
355	ret = cmpxchg(uaddr, oldval, newval);
356
357#ifdef CONFIG_64BIT
358	pagefault_enable();
359#else
360	kunmap_atomic(uaddr);
361#endif
362	ret = 0;
363
364out_inatomic:
365	preempt_enable();
366	return ret;
367}
368EXPORT_SYMBOL(futex_atomic_cmpxchg_inatomic);
369