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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _ASM_IA64_UACCESS_H
3#define _ASM_IA64_UACCESS_H
4
5/*
6 * This file defines various macros to transfer memory areas across
7 * the user/kernel boundary. This needs to be done carefully because
8 * this code is executed in kernel mode and uses user-specified
9 * addresses. Thus, we need to be careful not to let the user to
10 * trick us into accessing kernel memory that would normally be
11 * inaccessible. This code is also fairly performance sensitive,
12 * so we want to spend as little time doing safety checks as
13 * possible.
14 *
15 * To make matters a bit more interesting, these macros sometimes also
16 * called from within the kernel itself, in which case the address
17 * validity check must be skipped. The get_fs() macro tells us what
18 * to do: if get_fs()==USER_DS, checking is performed, if
19 * get_fs()==KERNEL_DS, checking is bypassed.
20 *
21 * Note that even if the memory area specified by the user is in a
22 * valid address range, it is still possible that we'll get a page
23 * fault while accessing it. This is handled by filling out an
24 * exception handler fixup entry for each instruction that has the
25 * potential to fault. When such a fault occurs, the page fault
26 * handler checks to see whether the faulting instruction has a fixup
27 * associated and, if so, sets r8 to -EFAULT and clears r9 to 0 and
28 * then resumes execution at the continuation point.
29 *
30 * Based on <asm-alpha/uaccess.h>.
31 *
32 * Copyright (C) 1998, 1999, 2001-2004 Hewlett-Packard Co
33 * David Mosberger-Tang <davidm@hpl.hp.com>
34 */
35
36#include <linux/compiler.h>
37#include <linux/page-flags.h>
38#include <linux/mm.h>
39
40#include <asm/intrinsics.h>
41#include <asm/pgtable.h>
42#include <asm/io.h>
43#include <asm/extable.h>
44
45/*
46 * For historical reasons, the following macros are grossly misnamed:
47 */
48#define KERNEL_DS ((mm_segment_t) { ~0UL }) /* cf. access_ok() */
49#define USER_DS ((mm_segment_t) { TASK_SIZE-1 }) /* cf. access_ok() */
50
51#define get_ds() (KERNEL_DS)
52#define get_fs() (current_thread_info()->addr_limit)
53#define set_fs(x) (current_thread_info()->addr_limit = (x))
54
55#define segment_eq(a, b) ((a).seg == (b).seg)
56
57/*
58 * When accessing user memory, we need to make sure the entire area really is in
59 * user-level space. In order to do this efficiently, we make sure that the page at
60 * address TASK_SIZE is never valid. We also need to make sure that the address doesn't
61 * point inside the virtually mapped linear page table.
62 */
63static inline int __access_ok(const void __user *p, unsigned long size)
64{
65 unsigned long addr = (unsigned long)p;
66 unsigned long seg = get_fs().seg;
67 return likely(addr <= seg) &&
68 (seg == KERNEL_DS.seg || likely(REGION_OFFSET(addr) < RGN_MAP_LIMIT));
69}
70#define access_ok(type, addr, size) __access_ok((addr), (size))
71
72/*
73 * These are the main single-value transfer routines. They automatically
74 * use the right size if we just have the right pointer type.
75 *
76 * Careful to not
77 * (a) re-use the arguments for side effects (sizeof/typeof is ok)
78 * (b) require any knowledge of processes at this stage
79 */
80#define put_user(x, ptr) __put_user_check((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
81#define get_user(x, ptr) __get_user_check((x), (ptr), sizeof(*(ptr)))
82
83/*
84 * The "__xxx" versions do not do address space checking, useful when
85 * doing multiple accesses to the same area (the programmer has to do the
86 * checks by hand with "access_ok()")
87 */
88#define __put_user(x, ptr) __put_user_nocheck((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
89#define __get_user(x, ptr) __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
90
91#ifdef ASM_SUPPORTED
92 struct __large_struct { unsigned long buf[100]; };
93# define __m(x) (*(struct __large_struct __user *)(x))
94
95/* We need to declare the __ex_table section before we can use it in .xdata. */
96asm (".section \"__ex_table\", \"a\"\n\t.previous");
97
98# define __get_user_size(val, addr, n, err) \
99do { \
100 register long __gu_r8 asm ("r8") = 0; \
101 register long __gu_r9 asm ("r9"); \
102 asm ("\n[1:]\tld"#n" %0=%2%P2\t// %0 and %1 get overwritten by exception handler\n" \
103 "\t.xdata4 \"__ex_table\", 1b-., 1f-.+4\n" \
104 "[1:]" \
105 : "=r"(__gu_r9), "=r"(__gu_r8) : "m"(__m(addr)), "1"(__gu_r8)); \
106 (err) = __gu_r8; \
107 (val) = __gu_r9; \
108} while (0)
109
110/*
111 * The "__put_user_size()" macro tells gcc it reads from memory instead of writing it. This
112 * is because they do not write to any memory gcc knows about, so there are no aliasing
113 * issues.
114 */
115# define __put_user_size(val, addr, n, err) \
116do { \
117 register long __pu_r8 asm ("r8") = 0; \
118 asm volatile ("\n[1:]\tst"#n" %1=%r2%P1\t// %0 gets overwritten by exception handler\n" \
119 "\t.xdata4 \"__ex_table\", 1b-., 1f-.\n" \
120 "[1:]" \
121 : "=r"(__pu_r8) : "m"(__m(addr)), "rO"(val), "0"(__pu_r8)); \
122 (err) = __pu_r8; \
123} while (0)
124
125#else /* !ASM_SUPPORTED */
126# define RELOC_TYPE 2 /* ip-rel */
127# define __get_user_size(val, addr, n, err) \
128do { \
129 __ld_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE); \
130 (err) = ia64_getreg(_IA64_REG_R8); \
131 (val) = ia64_getreg(_IA64_REG_R9); \
132} while (0)
133# define __put_user_size(val, addr, n, err) \
134do { \
135 __st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE, \
136 (__force unsigned long) (val)); \
137 (err) = ia64_getreg(_IA64_REG_R8); \
138} while (0)
139#endif /* !ASM_SUPPORTED */
140
141extern void __get_user_unknown (void);
142
143/*
144 * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
145 * could clobber r8 and r9 (among others). Thus, be careful not to evaluate it while
146 * using r8/r9.
147 */
148#define __do_get_user(check, x, ptr, size) \
149({ \
150 const __typeof__(*(ptr)) __user *__gu_ptr = (ptr); \
151 __typeof__ (size) __gu_size = (size); \
152 long __gu_err = -EFAULT; \
153 unsigned long __gu_val = 0; \
154 if (!check || __access_ok(__gu_ptr, size)) \
155 switch (__gu_size) { \
156 case 1: __get_user_size(__gu_val, __gu_ptr, 1, __gu_err); break; \
157 case 2: __get_user_size(__gu_val, __gu_ptr, 2, __gu_err); break; \
158 case 4: __get_user_size(__gu_val, __gu_ptr, 4, __gu_err); break; \
159 case 8: __get_user_size(__gu_val, __gu_ptr, 8, __gu_err); break; \
160 default: __get_user_unknown(); break; \
161 } \
162 (x) = (__force __typeof__(*(__gu_ptr))) __gu_val; \
163 __gu_err; \
164})
165
166#define __get_user_nocheck(x, ptr, size) __do_get_user(0, x, ptr, size)
167#define __get_user_check(x, ptr, size) __do_get_user(1, x, ptr, size)
168
169extern void __put_user_unknown (void);
170
171/*
172 * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
173 * could clobber r8 (among others). Thus, be careful not to evaluate them while using r8.
174 */
175#define __do_put_user(check, x, ptr, size) \
176({ \
177 __typeof__ (x) __pu_x = (x); \
178 __typeof__ (*(ptr)) __user *__pu_ptr = (ptr); \
179 __typeof__ (size) __pu_size = (size); \
180 long __pu_err = -EFAULT; \
181 \
182 if (!check || __access_ok(__pu_ptr, __pu_size)) \
183 switch (__pu_size) { \
184 case 1: __put_user_size(__pu_x, __pu_ptr, 1, __pu_err); break; \
185 case 2: __put_user_size(__pu_x, __pu_ptr, 2, __pu_err); break; \
186 case 4: __put_user_size(__pu_x, __pu_ptr, 4, __pu_err); break; \
187 case 8: __put_user_size(__pu_x, __pu_ptr, 8, __pu_err); break; \
188 default: __put_user_unknown(); break; \
189 } \
190 __pu_err; \
191})
192
193#define __put_user_nocheck(x, ptr, size) __do_put_user(0, x, ptr, size)
194#define __put_user_check(x, ptr, size) __do_put_user(1, x, ptr, size)
195
196/*
197 * Complex access routines
198 */
199extern unsigned long __must_check __copy_user (void __user *to, const void __user *from,
200 unsigned long count);
201
202static inline unsigned long
203raw_copy_to_user(void __user *to, const void *from, unsigned long count)
204{
205 return __copy_user(to, (__force void __user *) from, count);
206}
207
208static inline unsigned long
209raw_copy_from_user(void *to, const void __user *from, unsigned long count)
210{
211 return __copy_user((__force void __user *) to, from, count);
212}
213
214#define INLINE_COPY_FROM_USER
215#define INLINE_COPY_TO_USER
216
217extern unsigned long __do_clear_user (void __user *, unsigned long);
218
219#define __clear_user(to, n) __do_clear_user(to, n)
220
221#define clear_user(to, n) \
222({ \
223 unsigned long __cu_len = (n); \
224 if (__access_ok(to, __cu_len)) \
225 __cu_len = __do_clear_user(to, __cu_len); \
226 __cu_len; \
227})
228
229
230/*
231 * Returns: -EFAULT if exception before terminator, N if the entire buffer filled, else
232 * strlen.
233 */
234extern long __must_check __strncpy_from_user (char *to, const char __user *from, long to_len);
235
236#define strncpy_from_user(to, from, n) \
237({ \
238 const char __user * __sfu_from = (from); \
239 long __sfu_ret = -EFAULT; \
240 if (__access_ok(__sfu_from, 0)) \
241 __sfu_ret = __strncpy_from_user((to), __sfu_from, (n)); \
242 __sfu_ret; \
243})
244
245/*
246 * Returns: 0 if exception before NUL or reaching the supplied limit
247 * (N), a value greater than N if the limit would be exceeded, else
248 * strlen.
249 */
250extern unsigned long __strnlen_user (const char __user *, long);
251
252#define strnlen_user(str, len) \
253({ \
254 const char __user *__su_str = (str); \
255 unsigned long __su_ret = 0; \
256 if (__access_ok(__su_str, 0)) \
257 __su_ret = __strnlen_user(__su_str, len); \
258 __su_ret; \
259})
260
261#define ARCH_HAS_TRANSLATE_MEM_PTR 1
262static __inline__ void *
263xlate_dev_mem_ptr(phys_addr_t p)
264{
265 struct page *page;
266 void *ptr;
267
268 page = pfn_to_page(p >> PAGE_SHIFT);
269 if (PageUncached(page))
270 ptr = (void *)p + __IA64_UNCACHED_OFFSET;
271 else
272 ptr = __va(p);
273
274 return ptr;
275}
276
277/*
278 * Convert a virtual cached kernel memory pointer to an uncached pointer
279 */
280static __inline__ void *
281xlate_dev_kmem_ptr(void *p)
282{
283 struct page *page;
284 void *ptr;
285
286 page = virt_to_page((unsigned long)p);
287 if (PageUncached(page))
288 ptr = (void *)__pa(p) + __IA64_UNCACHED_OFFSET;
289 else
290 ptr = p;
291
292 return ptr;
293}
294
295#endif /* _ASM_IA64_UACCESS_H */