arch/tile/lib/memcpy_user_64.c

   1 /*
   2  * Copyright 2011 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * Do memcpy(), but trap and return "n" when a load or store faults.
  15  *
  16  * Note: this idiom only works when memcpy() compiles to a leaf function.
  17  * Here leaf function not only means it does not have calls, but also
  18  * requires no stack operations (sp, stack frame pointer) and no
  19  * use of callee-saved registers, else "jrp lr" will be incorrect since
  20  * unwinding stack frame is bypassed. Since memcpy() is not complex so
  21  * these conditions are satisfied here, but we need to be careful when
  22  * modifying this file. This is not a clean solution but is the best
  23  * one so far.
  24  *
  25  * Also note that we are capturing "n" from the containing scope here.
  26  */
  27
  28 #define _ST(p, inst, v)                                         \
  29         ({                                                      \
  30                 asm("1: " #inst " %0, %1;"                      \
  31                     ".pushsection .coldtext.memcpy,\"ax\";"     \
  32                     "2: { move r0, %2; jrp lr };"               \
  33                     ".section __ex_table,\"a\";"                \
  34                     ".align 8;"                                 \
  35                     ".quad 1b, 2b;"                             \
  36                     ".popsection"                               \
  37                     : "=m" (*(p)) : "r" (v), "r" (n));          \
  38         })
  39
  40 #define _LD(p, inst)                                            \
  41         ({                                                      \
  42                 unsigned long __v;                              \
  43                 asm("1: " #inst " %0, %1;"                      \
  44                     ".pushsection .coldtext.memcpy,\"ax\";"     \
  45                     "2: { move r0, %2; jrp lr };"               \
  46                     ".section __ex_table,\"a\";"                \
  47                     ".align 8;"                                 \
  48                     ".quad 1b, 2b;"                             \
  49                     ".popsection"                               \
  50                     : "=r" (__v) : "m" (*(p)), "r" (n));        \
  51                 __v;                                            \
  52         })
  53
  54 #define USERCOPY_FUNC __copy_to_user_inatomic
  55 #define ST1(p, v) _ST((p), st1, (v))
  56 #define ST2(p, v) _ST((p), st2, (v))
  57 #define ST4(p, v) _ST((p), st4, (v))
  58 #define ST8(p, v) _ST((p), st, (v))
  59 #define LD1 LD
  60 #define LD2 LD
  61 #define LD4 LD
  62 #define LD8 LD
  63 #include "memcpy_64.c"
  64
  65 #define USERCOPY_FUNC __copy_from_user_inatomic
  66 #define ST1 ST
  67 #define ST2 ST
  68 #define ST4 ST
  69 #define ST8 ST
  70 #define LD1(p) _LD((p), ld1u)
  71 #define LD2(p) _LD((p), ld2u)
  72 #define LD4(p) _LD((p), ld4u)
  73 #define LD8(p) _LD((p), ld)
  74 #include "memcpy_64.c"
  75
  76 #define USERCOPY_FUNC __copy_in_user_inatomic
  77 #define ST1(p, v) _ST((p), st1, (v))
  78 #define ST2(p, v) _ST((p), st2, (v))
  79 #define ST4(p, v) _ST((p), st4, (v))
  80 #define ST8(p, v) _ST((p), st, (v))
  81 #define LD1(p) _LD((p), ld1u)
  82 #define LD2(p) _LD((p), ld2u)
  83 #define LD4(p) _LD((p), ld4u)
  84 #define LD8(p) _LD((p), ld)
  85 #include "memcpy_64.c"
  86
  87 unsigned long __copy_from_user_zeroing(void *to, const void __user *from,
  88                                        unsigned long n)
  89 {
  90         unsigned long rc = __copy_from_user_inatomic(to, from, n);
  91         if (unlikely(rc))
  92                 memset(to + n - rc, 0, rc);
  93         return rc;
  94 }