cregit-Linux how code gets into the kernel

Release 4.11 arch/alpha/include/asm/uaccess.h

#ifndef __ALPHA_UACCESS_H

#define __ALPHA_UACCESS_H

#include <linux/errno.h>
#include <linux/sched.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 VERIFY_READ	0

#define VERIFY_WRITE	1


#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, segment) \
	(((segment).seg & (addr | size | (addr+size))) == 0)


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

/*
 * 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)), get_fs())

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

/*
 * 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.
 */

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, segment)				\
({                                                                      \
        long __gu_err = -EFAULT;                                        \
        unsigned long __gu_val = 0;                                     \
        const __typeof__(*(ptr)) __user *__gu_addr = (ptr);             \
        if (__access_ok((unsigned long)__gu_addr, size, segment)) {     \
                __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"                                          \
        ".section __ex_table,\"a\"\n"                   \
        "       .long 1b - .\n"                         \
        "       lda %0, 2b-1b(%1)\n"                    \
        ".previous"                                     \
                : "=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"                                          \
        ".section __ex_table,\"a\"\n"                   \
        "       .long 1b - .\n"                         \
        "       lda %0, 2b-1b(%1)\n"                    \
        ".previous"                                     \
                : "=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"                                          \
        ".section __ex_table,\"a\"\n"                   \
        "       .long 1b - .\n"                         \
        "       lda %0, 2b-1b(%1)\n"                    \
        ".previous"                                     \
                : "=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"                                          \
        ".section __ex_table,\"a\"\n"                   \
        "       .long 1b - .\n"                         \
        "       lda %0, 2b-1b(%1)\n"                    \
        ".previous"                                     \
                : "=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"                                                          \
        ".section __ex_table,\"a\"\n"                                   \
        "       .long 1b - .\n"                                         \
        "       lda %0, 3b-1b(%2)\n"                                    \
        "       .long 2b - .\n"                                         \
        "       lda %0, 3b-2b(%2)\n"                                    \
        ".previous"                                                     \
                : "=&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"                                                          \
        ".section __ex_table,\"a\"\n"                                   \
        "       .long 1b - .\n"                                         \
        "       lda %0, 2b-1b(%1)\n"                                    \
        ".previous"                                                     \
                : "=&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, segment)				\
({                                                                      \
        long __pu_err = -EFAULT;                                        \
        __typeof__(*(ptr)) __user *__pu_addr = (ptr);                   \
        if (__access_ok((unsigned long)__pu_addr, size, segment)) {     \
                __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"                                                  \
        ".section __ex_table,\"a\"\n"                           \
        "       .long 1b - .\n"                                 \
        "       lda $31,2b-1b(%0)\n"                            \
        ".previous"                                             \
                : "=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"                                                  \
        ".section __ex_table,\"a\"\n"                           \
        "       .long 1b - .\n"                                 \
        "       lda $31,2b-1b(%0)\n"                            \
        ".previous"                                             \
                : "=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"                                                  \
        ".section __ex_table,\"a\"\n"                           \
        "       .long 1b - .\n"                                 \
        "       lda $31,2b-1b(%0)\n"                            \
        ".previous"                                             \
                : "=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"                                                  \
        ".section __ex_table,\"a\"\n"                           \
        "       .long 1b - .\n"                                 \
        "       lda $31,2b-1b(%0)\n"                            \
        ".previous"                                             \
                : "=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"                                                  \
        ".section __ex_table,\"a\"\n"                           \
        "       .long 1b - .\n"                                 \
        "       lda $31, 5b-1b(%0)\n"                           \
        "       .long 2b - .\n"                                 \
        "       lda $31, 5b-2b(%0)\n"                           \
        "       .long 3b - .\n"                                 \
        "       lda $31, 5b-3b(%0)\n"                           \
        "       .long 4b - .\n"                                 \
        "       lda $31, 5b-4b(%0)\n"                           \
        ".previous"                                             \
                : "=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"                                                  \
        ".section __ex_table,\"a\"\n"                           \
        "       .long 1b - .\n"                                 \
        "       lda $31, 3b-1b(%0)\n"                           \
        "       .long 2b - .\n"                                 \
        "       lda $31, 3b-2b(%0)\n"                           \
        ".previous"                                             \
                : "=r"(__pu_err),                               \
                  "=&r"(__pu_tmp1), "=&r"(__pu_tmp2)            \
                : "r"((unsigned long)(x)), "r"(addr), "0"(__pu_err)); \
}
#endif


/*
 * Complex access routines
 */

/* This little bit of silliness is to get the GP loaded for a function
   that ordinarily wouldn't.  Otherwise we could have it done by the macro
   directly, which can be optimized the linker.  */
#ifdef MODULE

#define __module_address(sym)		"r"(sym),

#define __module_call(ra, arg, sym)	"jsr $" #ra ",(%" #arg ")," #sym
#else

#define __module_address(sym)

#define __module_call(ra, arg, sym)	"bsr $" #ra "," #sym " !samegp"
#endif

extern void __copy_user(void);


extern inline long __copy_tofrom_user_nocheck(void *to, const void *from, long len) { register void * __cu_to __asm__("$6") = to; register const void * __cu_from __asm__("$7") = from; register long __cu_len __asm__("$0") = len; __asm__ __volatile__( __module_call(28, 3, __copy_user) : "=r" (__cu_len), "=r" (__cu_from), "=r" (__cu_to) : __module_address(__copy_user) "0" (__cu_len), "1" (__cu_from), "2" (__cu_to) : "$1", "$2", "$3", "$4", "$5", "$28", "memory"); return __cu_len; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)5798.28%150.00%
Michael S. Tsirkin11.72%150.00%
Total58100.00%2100.00%

#define __copy_to_user(to, from, n) \ ({ \ __chk_user_ptr(to); \ __copy_tofrom_user_nocheck((__force void *)(to), (from), (n)); \ }) #define __copy_from_user(to, from, n) \ ({ \ __chk_user_ptr(from); \ __copy_tofrom_user_nocheck((to), (__force void *)(from), (n)); \ }) #define __copy_to_user_inatomic __copy_to_user #define __copy_from_user_inatomic __copy_from_user
extern inline long copy_to_user(void __user *to, const void *from, long n) { if (likely(__access_ok((unsigned long)to, n, get_fs()))) n = __copy_tofrom_user_nocheck((__force void *)to, from, n); return n; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro3153.45%360.00%
Linus Torvalds (pre-git)2746.55%240.00%
Total58100.00%5100.00%


extern inline long copy_from_user(void *to, const void __user *from, long n) { long res = n; if (likely(__access_ok((unsigned long)from, n, get_fs()))) res = __copy_from_user_inatomic(to, from, n); if (unlikely(res)) memset(to + (n - res), 0, res); return res; }

Contributors

PersonTokensPropCommitsCommitProp
Al Viro5265.00%350.00%
Linus Torvalds (pre-git)2835.00%350.00%
Total80100.00%6100.00%

extern void __do_clear_user(void);
extern inline long __clear_user(void __user *to, long len) { register void __user * __cl_to __asm__("$6") = to; register long __cl_len __asm__("$0") = len; __asm__ __volatile__( __module_call(28, 2, __do_clear_user) : "=r"(__cl_len), "=r"(__cl_to) : __module_address(__do_clear_user) "0"(__cl_len), "1"(__cl_to) : "$1", "$2", "$3", "$4", "$5", "$28", "memory"); return __cl_len; }

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)4093.02%250.00%
Al Viro24.65%125.00%
Michael S. Tsirkin12.33%125.00%
Total43100.00%4100.00%


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

Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)3683.72%240.00%
Richard Henderson511.63%120.00%
Al Viro24.65%240.00%
Total43100.00%5100.00%

#undef __module_address #undef __module_call #define user_addr_max() \ (segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL) extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strlen_user(const char __user *str); extern __must_check long strnlen_user(const char __user *str, long n); /* * About the exception table: * * - insn is a 32-bit pc-relative offset from the faulting insn. * - nextinsn is a 16-bit offset off of the faulting instruction * (not off of the *next* instruction as branches are). * - errreg is the register in which to place -EFAULT. * - valreg is the final target register for the load sequence * and will be zeroed. * * Either errreg or valreg may be $31, in which case nothing happens. * * The exception fixup information "just so happens" to be arranged * as in a MEM format instruction. This lets us emit our three * values like so: * * lda valreg, nextinsn(errreg) * */ struct exception_table_entry { signed int insn; union exception_fixup { unsigned unit; struct { signed int nextinsn : 16; unsigned int errreg : 5; unsigned int valreg : 5; } bits; } fixup; }; /* Returns the new pc */ #define fixup_exception(map_reg, _fixup, pc) \ ({ \ if ((_fixup)->fixup.bits.valreg != 31) \ map_reg((_fixup)->fixup.bits.valreg) = 0; \ if ((_fixup)->fixup.bits.errreg != 31) \ map_reg((_fixup)->fixup.bits.errreg) = -EFAULT; \ (pc) + (_fixup)->fixup.bits.nextinsn; \ }) #define ARCH_HAS_RELATIVE_EXTABLE #define swap_ex_entry_fixup(a, b, tmp, delta) \ do { \ (a)->fixup.unit = (b)->fixup.unit; \ (b)->fixup.unit = (tmp).fixup.unit; \ } while (0) #endif /* __ALPHA_UACCESS_H */

Overall Contributors

PersonTokensPropCommitsCommitProp
Linus Torvalds (pre-git)62474.37%1140.74%
Al Viro9311.08%518.52%
Richard Henderson677.99%311.11%
Michael S. Tsirkin151.79%27.41%
Ard Biesheuvel131.55%13.70%
Michael Cree121.43%13.70%
Ingo Molnar80.95%13.70%
Ivan Kokshaysky40.48%13.70%
Roel Kluin20.24%13.70%
Alan Cox10.12%13.70%
Total839100.00%27100.00%
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