arch/ia64/include/asm/uaccess.h

   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_fs()  (current_thread_info()->addr_limit)
  52 #define set_fs(x) (current_thread_info()->addr_limit = (x))
  53
  54 #define segment_eq(a, b)        ((a).seg == (b).seg)
  55
  56 /*
  57  * When accessing user memory, we need to make sure the entire area really is in
  58  * user-level space.  In order to do this efficiently, we make sure that the page at
  59  * address TASK_SIZE is never valid.  We also need to make sure that the address doesn't
  60  * point inside the virtually mapped linear page table.
  61  */
  62 static inline int __access_ok(const void __user *p, unsigned long size)
  63 {
  64         unsigned long addr = (unsigned long)p;
  65         unsigned long seg = get_fs().seg;
  66         return likely(addr <= seg) &&
  67          (seg == KERNEL_DS.seg || likely(REGION_OFFSET(addr) < RGN_MAP_LIMIT));
  68 }
  69 #define access_ok(addr, size)   __access_ok((addr), (size))
  70
  71 /*
  72  * These are the main single-value transfer routines.  They automatically
  73  * use the right size if we just have the right pointer type.
  74  *
  75  * Careful to not
  76  * (a) re-use the arguments for side effects (sizeof/typeof is ok)
  77  * (b) require any knowledge of processes at this stage
  78  */
  79 #define put_user(x, ptr)        __put_user_check((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
  80 #define get_user(x, ptr)        __get_user_check((x), (ptr), sizeof(*(ptr)))
  81
  82 /*
  83  * The "__xxx" versions do not do address space checking, useful when
  84  * doing multiple accesses to the same area (the programmer has to do the
  85  * checks by hand with "access_ok()")
  86  */
  87 #define __put_user(x, ptr)      __put_user_nocheck((__typeof__(*(ptr))) (x), (ptr), sizeof(*(ptr)))
  88 #define __get_user(x, ptr)      __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  89
  90 #ifdef ASM_SUPPORTED
  91   struct __large_struct { unsigned long buf[100]; };
  92 # define __m(x) (*(struct __large_struct __user *)(x))
  93
  94 /* We need to declare the __ex_table section before we can use it in .xdata.  */
  95 asm (".section \"__ex_table\", \"a\"\n\t.previous");
  96
  97 # define __get_user_size(val, addr, n, err)                                                     \
  98 do {                                                                                            \
  99         register long __gu_r8 asm ("r8") = 0;                                                   \
 100         register long __gu_r9 asm ("r9");                                                       \
 101         asm ("\n[1:]\tld"#n" %0=%2%P2\t// %0 and %1 get overwritten by exception handler\n"     \
 102              "\t.xdata4 \"__ex_table\", 1b-., 1f-.+4\n"                                         \
 103              "[1:]"                                                                             \
 104              : "=r"(__gu_r9), "=r"(__gu_r8) : "m"(__m(addr)), "1"(__gu_r8));                    \
 105         (err) = __gu_r8;                                                                        \
 106         (val) = __gu_r9;                                                                        \
 107 } while (0)
 108
 109 /*
 110  * The "__put_user_size()" macro tells gcc it reads from memory instead of writing it.  This
 111  * is because they do not write to any memory gcc knows about, so there are no aliasing
 112  * issues.
 113  */
 114 # define __put_user_size(val, addr, n, err)                                                     \
 115 do {                                                                                            \
 116         register long __pu_r8 asm ("r8") = 0;                                                   \
 117         asm volatile ("\n[1:]\tst"#n" %1=%r2%P1\t// %0 gets overwritten by exception handler\n" \
 118                       "\t.xdata4 \"__ex_table\", 1b-., 1f-.\n"                                  \
 119                       "[1:]"                                                                    \
 120                       : "=r"(__pu_r8) : "m"(__m(addr)), "rO"(val), "0"(__pu_r8));               \
 121         (err) = __pu_r8;                                                                        \
 122 } while (0)
 123
 124 #else /* !ASM_SUPPORTED */
 125 # define RELOC_TYPE     2       /* ip-rel */
 126 # define __get_user_size(val, addr, n, err)                             \
 127 do {                                                                    \
 128         __ld_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE);   \
 129         (err) = ia64_getreg(_IA64_REG_R8);                              \
 130         (val) = ia64_getreg(_IA64_REG_R9);                              \
 131 } while (0)
 132 # define __put_user_size(val, addr, n, err)                             \
 133 do {                                                                    \
 134         __st_user("__ex_table", (unsigned long) addr, n, RELOC_TYPE,    \
 135                   (__force unsigned long) (val));                       \
 136         (err) = ia64_getreg(_IA64_REG_R8);                              \
 137 } while (0)
 138 #endif /* !ASM_SUPPORTED */
 139
 140 extern void __get_user_unknown (void);
 141
 142 /*
 143  * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
 144  * could clobber r8 and r9 (among others).  Thus, be careful not to evaluate it while
 145  * using r8/r9.
 146  */
 147 #define __do_get_user(check, x, ptr, size)                                              \
 148 ({                                                                                      \
 149         const __typeof__(*(ptr)) __user *__gu_ptr = (ptr);                              \
 150         __typeof__ (size) __gu_size = (size);                                           \
 151         long __gu_err = -EFAULT;                                                        \
 152         unsigned long __gu_val = 0;                                                     \
 153         if (!check || __access_ok(__gu_ptr, size))                                      \
 154                 switch (__gu_size) {                                                    \
 155                       case 1: __get_user_size(__gu_val, __gu_ptr, 1, __gu_err); break;  \
 156                       case 2: __get_user_size(__gu_val, __gu_ptr, 2, __gu_err); break;  \
 157                       case 4: __get_user_size(__gu_val, __gu_ptr, 4, __gu_err); break;  \
 158                       case 8: __get_user_size(__gu_val, __gu_ptr, 8, __gu_err); break;  \
 159                       default: __get_user_unknown(); break;                             \
 160                 }                                                                       \
 161         (x) = (__force __typeof__(*(__gu_ptr))) __gu_val;                               \
 162         __gu_err;                                                                       \
 163 })
 164
 165 #define __get_user_nocheck(x, ptr, size)        __do_get_user(0, x, ptr, size)
 166 #define __get_user_check(x, ptr, size)  __do_get_user(1, x, ptr, size)
 167
 168 extern void __put_user_unknown (void);
 169
 170 /*
 171  * Evaluating arguments X, PTR, SIZE, and SEGMENT may involve subroutine-calls, which
 172  * could clobber r8 (among others).  Thus, be careful not to evaluate them while using r8.
 173  */
 174 #define __do_put_user(check, x, ptr, size)                                              \
 175 ({                                                                                      \
 176         __typeof__ (x) __pu_x = (x);                                                    \
 177         __typeof__ (*(ptr)) __user *__pu_ptr = (ptr);                                   \
 178         __typeof__ (size) __pu_size = (size);                                           \
 179         long __pu_err = -EFAULT;                                                        \
 180                                                                                         \
 181         if (!check || __access_ok(__pu_ptr, __pu_size))                                 \
 182                 switch (__pu_size) {                                                    \
 183                       case 1: __put_user_size(__pu_x, __pu_ptr, 1, __pu_err); break;    \
 184                       case 2: __put_user_size(__pu_x, __pu_ptr, 2, __pu_err); break;    \
 185                       case 4: __put_user_size(__pu_x, __pu_ptr, 4, __pu_err); break;    \
 186                       case 8: __put_user_size(__pu_x, __pu_ptr, 8, __pu_err); break;    \
 187                       default: __put_user_unknown(); break;                             \
 188                 }                                                                       \
 189         __pu_err;                                                                       \
 190 })
 191
 192 #define __put_user_nocheck(x, ptr, size)        __do_put_user(0, x, ptr, size)
 193 #define __put_user_check(x, ptr, size)  __do_put_user(1, x, ptr, size)
 194
 195 /*
 196  * Complex access routines
 197  */
 198 extern unsigned long __must_check __copy_user (void __user *to, const void __user *from,
 199                                                unsigned long count);
 200
 201 static inline unsigned long
 202 raw_copy_to_user(void __user *to, const void *from, unsigned long count)
 203 {
 204         return __copy_user(to, (__force void __user *) from, count);
 205 }
 206
 207 static inline unsigned long
 208 raw_copy_from_user(void *to, const void __user *from, unsigned long count)
 209 {
 210         return __copy_user((__force void __user *) to, from, count);
 211 }
 212
 213 #define INLINE_COPY_FROM_USER
 214 #define INLINE_COPY_TO_USER
 215
 216 extern unsigned long __do_clear_user (void __user *, unsigned long);
 217
 218 #define __clear_user(to, n)             __do_clear_user(to, n)
 219
 220 #define clear_user(to, n)                                       \
 221 ({                                                              \
 222         unsigned long __cu_len = (n);                           \
 223         if (__access_ok(to, __cu_len))                          \
 224                 __cu_len = __do_clear_user(to, __cu_len);       \
 225         __cu_len;                                               \
 226 })
 227
 228
 229 /*
 230  * Returns: -EFAULT if exception before terminator, N if the entire buffer filled, else
 231  * strlen.
 232  */
 233 extern long __must_check __strncpy_from_user (char *to, const char __user *from, long to_len);
 234
 235 #define strncpy_from_user(to, from, n)                                  \
 236 ({                                                                      \
 237         const char __user * __sfu_from = (from);                        \
 238         long __sfu_ret = -EFAULT;                                       \
 239         if (__access_ok(__sfu_from, 0))                                 \
 240                 __sfu_ret = __strncpy_from_user((to), __sfu_from, (n)); \
 241         __sfu_ret;                                                      \
 242 })
 243
 244 /*
 245  * Returns: 0 if exception before NUL or reaching the supplied limit
 246  * (N), a value greater than N if the limit would be exceeded, else
 247  * strlen.
 248  */
 249 extern unsigned long __strnlen_user (const char __user *, long);
 250
 251 #define strnlen_user(str, len)                                  \
 252 ({                                                              \
 253         const char __user *__su_str = (str);                    \
 254         unsigned long __su_ret = 0;                             \
 255         if (__access_ok(__su_str, 0))                           \
 256                 __su_ret = __strnlen_user(__su_str, len);       \
 257         __su_ret;                                               \
 258 })
 259
 260 #define ARCH_HAS_TRANSLATE_MEM_PTR      1
 261 static __inline__ void *
 262 xlate_dev_mem_ptr(phys_addr_t p)
 263 {
 264         struct page *page;
 265         void *ptr;
 266
 267         page = pfn_to_page(p >> PAGE_SHIFT);
 268         if (PageUncached(page))
 269                 ptr = (void *)p + __IA64_UNCACHED_OFFSET;
 270         else
 271                 ptr = __va(p);
 272
 273         return ptr;
 274 }
 275
 276 /*
 277  * Convert a virtual cached kernel memory pointer to an uncached pointer
 278  */
 279 static __inline__ void *
 280 xlate_dev_kmem_ptr(void *p)
 281 {
 282         struct page *page;
 283         void *ptr;
 284
 285         page = virt_to_page((unsigned long)p);
 286         if (PageUncached(page))
 287                 ptr = (void *)__pa(p) + __IA64_UNCACHED_OFFSET;
 288         else
 289                 ptr = p;
 290
 291         return ptr;
 292 }
 293
 294 #endif /* _ASM_IA64_UACCESS_H */