linux/arch/tile/lib/memcpy_user_64.c
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   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                    ".quad 1b, 2b;"                             \
  35                    ".popsection"                               \
  36                    : "=m" (*(p)) : "r" (v), "r" (n));          \
  37        })
  38
  39#define _LD(p, inst)                                            \
  40        ({                                                      \
  41                unsigned long __v;                              \
  42                asm("1: " #inst " %0, %1;"                      \
  43                    ".pushsection .coldtext.memcpy,\"ax\";"     \
  44                    "2: { move r0, %2; jrp lr };"               \
  45                    ".section __ex_table,\"a\";"                \
  46                    ".quad 1b, 2b;"                             \
  47                    ".popsection"                               \
  48                    : "=r" (__v) : "m" (*(p)), "r" (n));        \
  49                __v;                                            \
  50        })
  51
  52#define USERCOPY_FUNC __copy_to_user_inatomic
  53#define ST1(p, v) _ST((p), st1, (v))
  54#define ST2(p, v) _ST((p), st2, (v))
  55#define ST4(p, v) _ST((p), st4, (v))
  56#define ST8(p, v) _ST((p), st, (v))
  57#define LD1 LD
  58#define LD2 LD
  59#define LD4 LD
  60#define LD8 LD
  61#include "memcpy_64.c"
  62
  63#define USERCOPY_FUNC __copy_from_user_inatomic
  64#define ST1 ST
  65#define ST2 ST
  66#define ST4 ST
  67#define ST8 ST
  68#define LD1(p) _LD((p), ld1u)
  69#define LD2(p) _LD((p), ld2u)
  70#define LD4(p) _LD((p), ld4u)
  71#define LD8(p) _LD((p), ld)
  72#include "memcpy_64.c"
  73
  74#define USERCOPY_FUNC __copy_in_user_inatomic
  75#define ST1(p, v) _ST((p), st1, (v))
  76#define ST2(p, v) _ST((p), st2, (v))
  77#define ST4(p, v) _ST((p), st4, (v))
  78#define ST8(p, v) _ST((p), st, (v))
  79#define LD1(p) _LD((p), ld1u)
  80#define LD2(p) _LD((p), ld2u)
  81#define LD4(p) _LD((p), ld4u)
  82#define LD8(p) _LD((p), ld)
  83#include "memcpy_64.c"
  84
  85unsigned long __copy_from_user_zeroing(void *to, const void __user *from,
  86                                       unsigned long n)
  87{
  88        unsigned long rc = __copy_from_user_inatomic(to, from, n);
  89        if (unlikely(rc))
  90                memset(to + n - rc, 0, rc);
  91        return rc;
  92}
  93