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 */ 63 static 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. */ 96 asm (".section \"__ex_table\", \"a\"\n\t.previous"); 97 98 # define __get_user_size(val, addr, n, err) \ 99 do { \ 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) \ 116 do { \ 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) \ 128 do { \ 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) \ 134 do { \ 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 */ 140 141 extern 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) 168 169 extern 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 */ 199 extern unsigned long __must_check __copy_user (void __user *to, const void __user *from, 200 unsigned long count); 201 202 static inline unsigned long 203 raw_copy_to_user(void __user *to, const void *from, unsigned long count) 204 { 205 return __copy_user(to, (__force void __user *) from, count); 206 } 207 208 static inline unsigned long 209 raw_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 216 217 extern 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 */ 234 extern 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 */ 250 extern 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 1 262 static __inline__ void * 263 xlate_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 */ 280 static __inline__ void * 281 xlate_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 */ 296