uaccess.h 9.4 KB
Newer Older
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
#ifndef _ASM_UACCES_H_
#define _ASM_UACCES_H_
/*
 * User space memory access functions
 */
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/thread_info.h>
#include <linux/prefetch.h>
#include <linux/string.h>
#include <asm/asm.h>
#include <asm/page.h>

#define VERIFY_READ 0
#define VERIFY_WRITE 1

/*
 * The fs value determines whether argument validity checking should be
 * performed or not.  If get_fs() == USER_DS, checking is performed, with
 * get_fs() == KERNEL_DS, checking is bypassed.
 *
 * For historical reasons, these macros are grossly misnamed.
 */

#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })

#define KERNEL_DS	MAKE_MM_SEG(-1UL)
#define USER_DS		MAKE_MM_SEG(PAGE_OFFSET)

#define get_ds()	(KERNEL_DS)
#define get_fs()	(current_thread_info()->addr_limit)
#define set_fs(x)	(current_thread_info()->addr_limit = (x))

#define segment_eq(a, b)	((a).seg == (b).seg)

36 37 38 39
#define __addr_ok(addr)					\
	((unsigned long __force)(addr) <		\
	 (current_thread_info()->addr_limit.seg))

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
/*
 * Test whether a block of memory is a valid user space address.
 * Returns 0 if the range is valid, nonzero otherwise.
 *
 * This is equivalent to the following test:
 * (u33)addr + (u33)size >= (u33)current->addr_limit.seg (u65 for x86_64)
 *
 * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
 */

#define __range_not_ok(addr, size)					\
({									\
	unsigned long flag, roksum;					\
	__chk_user_ptr(addr);						\
	asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"		\
	    : "=&r" (flag), "=r" (roksum)				\
	    : "1" (addr), "g" ((long)(size)),				\
	      "rm" (current_thread_info()->addr_limit.seg));		\
	flag;								\
})

/**
 * access_ok: - Checks if a user space pointer is valid
 * @type: Type of access: %VERIFY_READ or %VERIFY_WRITE.  Note that
 *        %VERIFY_WRITE is a superset of %VERIFY_READ - if it is safe
 *        to write to a block, it is always safe to read from it.
 * @addr: User space pointer to start of block to check
 * @size: Size of block to check
 *
 * Context: User context only.  This function may sleep.
 *
 * Checks if a pointer to a block of memory in user space is valid.
 *
 * Returns true (nonzero) if the memory block may be valid, false (zero)
 * if it is definitely invalid.
 *
 * Note that, depending on architecture, this function probably just
 * checks that the pointer is in the user space range - after calling
 * this function, memory access functions may still return -EFAULT.
 */
#define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))

/*
 * The exception table consists of pairs of addresses: the first is the
 * address of an instruction that is allowed to fault, and the second is
 * the address at which the program should continue.  No registers are
 * modified, so it is entirely up to the continuation code to figure out
 * what to do.
 *
 * All the routines below use bits of fixup code that are out of line
 * with the main instruction path.  This means when everything is well,
 * we don't even have to jump over them.  Further, they do not intrude
 * on our cache or tlb entries.
 */

struct exception_table_entry {
	unsigned long insn, fixup;
};

extern int fixup_exception(struct pt_regs *regs);

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * This gets kind of ugly. We want to return _two_ values in "get_user()"
 * and yet we don't want to do any pointers, because that is too much
 * of a performance impact. Thus we have a few rather ugly macros here,
 * and hide all the ugliness from the user.
 *
 * The "__xxx" versions of the user access functions are versions that
 * do not verify the address space, that must have been done previously
 * with a separate "access_ok()" call (this is used when we do multiple
 * accesses to the same area of user memory).
 */

extern int __get_user_1(void);
extern int __get_user_2(void);
extern int __get_user_4(void);
extern int __get_user_8(void);
extern int __get_user_bad(void);

#define __get_user_x(size, ret, x, ptr)		      \
	asm volatile("call __get_user_" #size	      \
		     : "=a" (ret),"=d" (x)	      \
		     : "0" (ptr))		      \

G
Glauber Costa 已提交
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
/* Careful: we have to cast the result to the type of the pointer
 * for sign reasons */

/**
 * get_user: - Get a simple variable from user space.
 * @x:   Variable to store result.
 * @ptr: Source address, in user space.
 *
 * Context: User context only.  This function may sleep.
 *
 * This macro copies a single simple variable from user space to kernel
 * space.  It supports simple types like char and int, but not larger
 * data types like structures or arrays.
 *
 * @ptr must have pointer-to-simple-variable type, and the result of
 * dereferencing @ptr must be assignable to @x without a cast.
 *
 * Returns zero on success, or -EFAULT on error.
 * On error, the variable @x is set to zero.
 */
#ifdef CONFIG_X86_32
#define __get_user_8(__ret_gu, __val_gu, ptr)				\
		__get_user_x(X, __ret_gu, __val_gu, ptr)
#else
#define __get_user_8(__ret_gu, __val_gu, ptr)				\
		__get_user_x(8, __ret_gu, __val_gu, ptr)
#endif

#define get_user(x, ptr)						\
({									\
	int __ret_gu;							\
	unsigned long __val_gu;						\
	__chk_user_ptr(ptr);						\
	switch (sizeof(*(ptr))) {					\
	case 1:								\
		__get_user_x(1, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 2:								\
		__get_user_x(2, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 4:								\
		__get_user_x(4, __ret_gu, __val_gu, ptr);		\
		break;							\
	case 8:								\
		__get_user_8(__ret_gu, __val_gu, ptr);			\
		break;							\
	default:							\
		__get_user_x(X, __ret_gu, __val_gu, ptr);		\
		break;							\
	}								\
	(x) = (__typeof__(*(ptr)))__val_gu;				\
	__ret_gu;							\
})

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
#ifdef CONFIG_X86_32
#define __put_user_u64(x, addr, err)					\
	asm volatile("1:	movl %%eax,0(%2)\n"			\
		     "2:	movl %%edx,4(%2)\n"			\
		     "3:\n"						\
		     ".section .fixup,\"ax\"\n"				\
		     "4:	movl %3,%0\n"				\
		     "	jmp 3b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE(1b, 4b)				\
		     _ASM_EXTABLE(2b, 4b)				\
		     : "=r" (err)					\
		     : "A" (x), "r" (addr), "i" (-EFAULT), "0" (err))
#else
#define __put_user_u64(x, ptr, retval) \
	__put_user_asm(x, ptr, retval, "q", "", "Zr", -EFAULT)
#endif

#ifdef CONFIG_X86_WP_WORKS_OK

#define __put_user_size(x, ptr, size, retval, errret)			\
do {									\
	retval = 0;							\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1:								\
		__put_user_asm(x, ptr, retval, "b", "b", "iq", errret);	\
		break;							\
	case 2:								\
		__put_user_asm(x, ptr, retval, "w", "w", "ir", errret);	\
		break;							\
	case 4:								\
		__put_user_asm(x, ptr, retval, "l", "k",  "ir", errret);\
		break;							\
	case 8:								\
		__put_user_u64((__typeof__(*ptr))(x), ptr, retval);	\
		break;							\
	default:							\
		__put_user_bad();					\
	}								\
} while (0)

#else

#define __put_user_size(x, ptr, size, retval, errret)			\
do {									\
	__typeof__(*(ptr))__pus_tmp = x;				\
	retval = 0;							\
									\
	if (unlikely(__copy_to_user_ll(ptr, &__pus_tmp, size) != 0))	\
		retval = errret;					\
} while (0)

#endif

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
#ifdef CONFIG_X86_32
#define __get_user_asm_u64(x, ptr, retval, errret)	(x) = __get_user_bad()
#else
#define __get_user_asm_u64(x, ptr, retval, errret) \
	 __get_user_asm(x, ptr, retval, "q", "", "=r", errret)
#endif

#define __get_user_size(x, ptr, size, retval, errret)			\
do {									\
	retval = 0;							\
	__chk_user_ptr(ptr);						\
	switch (size) {							\
	case 1:								\
		__get_user_asm(x, ptr, retval, "b", "b", "=q", errret);	\
		break;							\
	case 2:								\
		__get_user_asm(x, ptr, retval, "w", "w", "=r", errret);	\
		break;							\
	case 4:								\
		__get_user_asm(x, ptr, retval, "l", "k", "=r", errret);	\
		break;							\
	case 8:								\
		__get_user_asm_u64(x, ptr, retval, errret);		\
		break;							\
	default:							\
		(x) = __get_user_bad();					\
	}								\
} while (0)

#define __get_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
	asm volatile("1:	mov"itype" %2,%"rtype"1\n"		\
		     "2:\n"						\
		     ".section .fixup,\"ax\"\n"				\
		     "3:	mov %3,%0\n"				\
		     "	xor"itype" %"rtype"1,%"rtype"1\n"		\
		     "	jmp 2b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE(1b, 3b)				\
		     : "=r" (err), ltype(x)				\
		     : "m" (__m(addr)), "i" (errret), "0" (err))

277 278 279 280 281 282 283
#define __put_user_nocheck(x, ptr, size)			\
({								\
	long __pu_err;						\
	__put_user_size((x), (ptr), (size), __pu_err, -EFAULT);	\
	__pu_err;						\
})

284 285 286 287 288 289 290 291
#define __get_user_nocheck(x, ptr, size)				\
({									\
	long __gu_err;							\
	unsigned long __gu_val;						\
	__get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT);	\
	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
	__gu_err;							\
})
292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312

/* FIXME: this hack is definitely wrong -AK */
struct __large_struct { unsigned long buf[100]; };
#define __m(x) (*(struct __large_struct __user *)(x))

/*
 * Tell gcc we read from memory instead of writing: this is because
 * we do not write to any memory gcc knows about, so there are no
 * aliasing issues.
 */
#define __put_user_asm(x, addr, err, itype, rtype, ltype, errret)	\
	asm volatile("1:	mov"itype" %"rtype"1,%2\n"		\
		     "2:\n"						\
		     ".section .fixup,\"ax\"\n"				\
		     "3:	mov %3,%0\n"				\
		     "	jmp 2b\n"					\
		     ".previous\n"					\
		     _ASM_EXTABLE(1b, 3b)				\
		     : "=r"(err)					\
		     : ltype(x), "m" (__m(addr)), "i" (errret), "0" (err))

G
Glauber Costa 已提交
313

314 315 316 317 318
#ifdef CONFIG_X86_32
# include "uaccess_32.h"
#else
# include "uaccess_64.h"
#endif
319 320

#endif