cregit-Linux how code gets into the kernel

Release 4.14 arch/alpha/include/asm/uaccess.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ALPHA_UACCESS_H

#define __ALPHA_UACCESS_H

/*
 * 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.
 *
 * Or at least it did once upon a time.  Nowadays it is a mask that
 * defines which bits of the address space are off limits.  This is a
 * wee bit faster than the above.
 *
 * For historical reasons, these macros are grossly misnamed.
 */


#define KERNEL_DS	((mm_segment_t) { 0UL })

#define USER_DS		((mm_segment_t) { -0x40000000000UL })


#define get_fs()  (current_thread_info()->addr_limit)

#define get_ds()  (KERNEL_DS)

#define set_fs(x) (current_thread_info()->addr_limit = (x))


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

/*
 * Is a address valid? This does a straightforward calculation rather
 * than tests.
 *
 * Address valid if:
 *  - "addr" doesn't have any high-bits set
 *  - AND "size" doesn't have any high-bits set
 *  - AND "addr+size" doesn't have any high-bits set
 *  - OR we are in kernel mode.
 */

#define __access_ok(addr, size) \
	((get_fs().seg & (addr | size | (addr+size))) == 0)


#define access_ok(type, addr, size)			\
({                                                      \
        __chk_user_ptr(addr);                           \
        __access_ok(((unsigned long)(addr)), (size));   \
})

/*
 * These are the main single-value transfer routines.  They automatically
 * use the right size if we just have the right pointer type.
 *
 * As the alpha uses the same address space for kernel and user
 * data, we can just do these as direct assignments.  (Of course, the
 * exception handling means that it's no longer "just"...)
 *
 * Careful to not
 * (a) re-use the arguments for side effects (sizeof/typeof is ok)
 * (b) require any knowledge of processes at this stage
 */

#define put_user(x, ptr) \
  __put_user_check((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

#define get_user(x, ptr) \
  __get_user_check((x), (ptr), sizeof(*(ptr)))

/*
 * The "__xxx" versions do not do address space checking, useful when
 * doing multiple accesses to the same area (the programmer has to do the
 * checks by hand with "access_ok()")
 */

#define __put_user(x, ptr) \
  __put_user_nocheck((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)))

#define __get_user(x, ptr) \
  __get_user_nocheck((x), (ptr), sizeof(*(ptr)))
  
/*
 * The "lda %1, 2b-1b(%0)" bits are magic to get the assembler to
 * encode the bits we need for resolving the exception.  See the
 * more extensive comments with fixup_inline_exception below for
 * more information.
 */

#define EXC(label,cont,res,err)				\
	".section __ex_table,\"a\"\n"                   \
        "       .long "#label"-.\n"                     \
        "       lda "#res","#cont"-"#label"("#err")\n"  \
        ".previous\n"

extern void __get_user_unknown(void);


#define __get_user_nocheck(x, ptr, size)			\
({                                                              \
        long __gu_err = 0;                                      \
        unsigned long __gu_val;                                 \
        __chk_user_ptr(ptr);                                    \
        switch (size) {                                         \
          case 1: __get_user_8(ptr); break;                     \
          case 2: __get_user_16(ptr); break;                    \
          case 4: __get_user_32(ptr); break;                    \
          case 8: __get_user_64(ptr); break;                    \
          default: __get_user_unknown(); break;                 \
        }                                                       \
        (x) = (__force __typeof__(*(ptr))) __gu_val;            \
        __gu_err;                                               \
})


#define __get_user_check(x, ptr, size)				\
({                                                              \
        long __gu_err = -EFAULT;                                \
        unsigned long __gu_val = 0;                             \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);     \
        if (__access_ok((unsigned long)__gu_addr, size)) {      \
                __gu_err = 0;                                   \
                switch (size) {                                 \
                  case 1: __get_user_8(__gu_addr); break;       \
                  case 2: __get_user_16(__gu_addr); break;      \
                  case 4: __get_user_32(__gu_addr); break;      \
                  case 8: __get_user_64(__gu_addr); break;      \
                  default: __get_user_unknown(); break;         \
                }                                               \
        }                                                       \
        (x) = (__force __typeof__(*(ptr))) __gu_val;            \
        __gu_err;                                               \
})



struct __large_struct { unsigned long buf[100]; };

#define __m(x) (*(struct __large_struct __user *)(x))


#define __get_user_64(addr)				\
	__asm__("1: ldq %0,%2\n"                        \
        "2:\n"                                          \
        EXC(1b,2b,%0,%1)                                \
                : "=r"(__gu_val), "=r"(__gu_err)        \
                : "m"(__m(addr)), "1"(__gu_err))


#define __get_user_32(addr)				\
	__asm__("1: ldl %0,%2\n"                        \
        "2:\n"                                          \
        EXC(1b,2b,%0,%1)                                \
                : "=r"(__gu_val), "=r"(__gu_err)        \
                : "m"(__m(addr)), "1"(__gu_err))

#ifdef __alpha_bwx__
/* Those lucky bastards with ev56 and later CPUs can do byte/word moves.  */


#define __get_user_16(addr)				\
	__asm__("1: ldwu %0,%2\n"                       \
        "2:\n"                                          \
        EXC(1b,2b,%0,%1)                                \
                : "=r"(__gu_val), "=r"(__gu_err)        \
                : "m"(__m(addr)), "1"(__gu_err))


#define __get_user_8(addr)				\
	__asm__("1: ldbu %0,%2\n"                       \
        "2:\n"                                          \
        EXC(1b,2b,%0,%1)                                \
                : "=r"(__gu_val), "=r"(__gu_err)        \
                : "m"(__m(addr)), "1"(__gu_err))
#else
/* Unfortunately, we can't get an unaligned access trap for the sub-word
   load, so we have to do a general unaligned operation.  */


#define __get_user_16(addr)						\
{                                                                       \
        long __gu_tmp;                                                  \
        __asm__("1: ldq_u %0,0(%3)\n"                                   \
        "2:     ldq_u %1,1(%3)\n"                                       \
        "       extwl %0,%3,%0\n"                                       \
        "       extwh %1,%3,%1\n"                                       \
        "       or %0,%1,%0\n"                                          \
        "3:\n"                                                          \
        EXC(1b,3b,%0,%2)                                                \
        EXC(2b,3b,%0,%2)                                                \
                : "=&r"(__gu_val), "=&r"(__gu_tmp), "=r"(__gu_err)      \
                : "r"(addr), "2"(__gu_err));                            \
}


#define __get_user_8(addr)						\
	__asm__("1: ldq_u %0,0(%2)\n"                                   \
        "       extbl %0,%2,%0\n"                                       \
        "2:\n"                                                          \
        EXC(1b,2b,%0,%1)                                                \
                : "=&r"(__gu_val), "=r"(__gu_err)                       \
                : "r"(addr), "1"(__gu_err))
#endif

extern void __put_user_unknown(void);


#define __put_user_nocheck(x, ptr, size)			\
({                                                              \
        long __pu_err = 0;                                      \
        __chk_user_ptr(ptr);                                    \
        switch (size) {                                         \
          case 1: __put_user_8(x, ptr); break;                  \
          case 2: __put_user_16(x, ptr); break;                 \
          case 4: __put_user_32(x, ptr); break;                 \
          case 8: __put_user_64(x, ptr); break;                 \
          default: __put_user_unknown(); break;                 \
        }                                                       \
        __pu_err;                                               \
})


#define __put_user_check(x, ptr, size)				\
({                                                              \
        long __pu_err = -EFAULT;                                \
        __typeof__(*(ptr)) __user *__pu_addr = (ptr);           \
        if (__access_ok((unsigned long)__pu_addr, size)) {      \
                __pu_err = 0;                                   \
                switch (size) {                                 \
                  case 1: __put_user_8(x, __pu_addr); break;    \
                  case 2: __put_user_16(x, __pu_addr); break;   \
                  case 4: __put_user_32(x, __pu_addr); break;   \
                  case 8: __put_user_64(x, __pu_addr); break;   \
                  default: __put_user_unknown(); break;         \
                }                                               \
        }                                                       \
        __pu_err;                                               \
})

/*
 * The "__put_user_xx()" macros tell gcc they read from memory
 * instead of writing: this is because they do not write to
 * any memory gcc knows about, so there are no aliasing issues
 */

#define __put_user_64(x, addr)					\
__asm__ __volatile__("1: stq %r2,%1\n"                          \
        "2:\n"                                                  \
        EXC(1b,2b,$31,%0)                                       \
                : "=r"(__pu_err)                                \
                : "m" (__m(addr)), "rJ" (x), "0"(__pu_err))


#define __put_user_32(x, addr)					\
__asm__ __volatile__("1: stl %r2,%1\n"                          \
        "2:\n"                                                  \
        EXC(1b,2b,$31,%0)                                       \
                : "=r"(__pu_err)                                \
                : "m"(__m(addr)), "rJ"(x), "0"(__pu_err))

#ifdef __alpha_bwx__
/* Those lucky bastards with ev56 and later CPUs can do byte/word moves.  */


#define __put_user_16(x, addr)					\
__asm__ __volatile__("1: stw %r2,%1\n"                          \
        "2:\n"                                                  \
        EXC(1b,2b,$31,%0)                                       \
                : "=r"(__pu_err)                                \
                : "m"(__m(addr)), "rJ"(x), "0"(__pu_err))


#define __put_user_8(x, addr)					\
__asm__ __volatile__("1: stb %r2,%1\n"                          \
        "2:\n"                                                  \
        EXC(1b,2b,$31,%0)                                       \
                : "=r"(__pu_err)                                \
                : "m"(__m(addr)), "rJ"(x), "0"(__pu_err))
#else
/* Unfortunately, we can't get an unaligned access trap for the sub-word
   write, so we have to do a general unaligned operation.  */


#define __put_user_16(x, addr)					\
{                                                               \
        long __pu_tmp1, __pu_tmp2, __pu_tmp3, __pu_tmp4;        \
        __asm__ __volatile__(                                   \
        "1:     ldq_u %2,1(%5)\n"                               \
        "2:     ldq_u %1,0(%5)\n"                               \
        "       inswh %6,%5,%4\n"                               \
        "       inswl %6,%5,%3\n"                               \
        "       mskwh %2,%5,%2\n"                               \
        "       mskwl %1,%5,%1\n"                               \
        "       or %2,%4,%2\n"                                  \
        "       or %1,%3,%1\n"                                  \
        "3:     stq_u %2,1(%5)\n"                               \
        "4:     stq_u %1,0(%5)\n"                               \
        "5:\n"                                                  \
        EXC(1b,5b,$31,%0)                                       \
        EXC(2b,5b,$31,%0)                                       \
        EXC(3b,5b,$31,%0)                                       \
        EXC(4b,5b,$31,%0)                                       \
                : "=r"(__pu_err), "=&r"(__pu_tmp1),             \
                  "=&r"(__pu_tmp2), "=&r"(__pu_tmp3),           \
                  "=&r"(__pu_tmp4)                              \
                : "r"(addr), "r"((unsigned long)(x)), "0"(__pu_err)); \
}


#define __put_user_8(x, addr)					\
{                                                               \
        long __pu_tmp1, __pu_tmp2;                              \
        __asm__ __volatile__(                                   \
        "1:     ldq_u %1,0(%4)\n"                               \
        "       insbl %3,%4,%2\n"                               \
        "       mskbl %1,%4,%1\n"                               \
        "       or %1,%2,%1\n"                                  \
        "2:     stq_u %1,0(%4)\n"                               \
        "3:\n"                                                  \
        EXC(1b,3b,$31,%0)                                       \
        EXC(2b,3b,$31,%0)                                       \
                : "=r"(__pu_err),                               \
                  "=&r"(__pu_tmp1), "=&r"(__pu_tmp2)            \
                : "r"((unsigned long)(x)), "r"(addr), "0"(__pu_err)); \
}
#endif


/*
 * Complex access routines
 */

extern long __copy_user(void *to, const void *from, long len);


static inline unsigned long raw_copy_from_user(void *to, const void __user *from, unsigned long len) { return __copy_user(to, (__force const void *)from, len); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2052.63%342.86%
Al Viro1847.37%457.14%
Total38100.00%7100.00%


static inline unsigned long raw_copy_to_user(void __user *to, const void *from, unsigned long len) { return __copy_user((__force void *)to, from, len); }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)2259.46%250.00%
Al Viro1540.54%250.00%
Total37100.00%4100.00%

extern long __clear_user(void __user *to, long len);
extern inline long clear_user(void __user *to, long len) { if (__access_ok((unsigned long)to, len)) len = __clear_user(to, len); return len; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)3382.50%240.00%
Richard Henderson512.50%120.00%
Al Viro25.00%240.00%
Total40100.00%5100.00%

#define user_addr_max() \ (uaccess_kernel() ? ~0UL : TASK_SIZE) extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strnlen_user(const char __user *str, long n); #include <asm/extable.h> #endif /* __ALPHA_UACCESS_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)42080.61%1137.93%
Al Viro7814.97%1137.93%
Michael Cree101.92%13.45%
Richard Henderson71.34%26.90%
Michael S. Tsirkin40.77%26.90%
Alan Cox10.19%13.45%
Greg Kroah-Hartman10.19%13.45%
Total521100.00%29100.00%
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