arch/s390/lib/mem.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * String handling functions.
   4  *
   5  * Copyright IBM Corp. 2012
   6  */
   7
   8 #include <linux/linkage.h>
   9 #include <asm/export.h>
  10
  11 /*
  12  * void *memmove(void *dest, const void *src, size_t n)
  13  */
  14 ENTRY(memmove)
  15         ltgr    %r4,%r4
  16         lgr     %r1,%r2
  17         bzr     %r14
  18         aghi    %r4,-1
  19         clgr    %r2,%r3
  20         jnh     .Lmemmove_forward
  21         la      %r5,1(%r4,%r3)
  22         clgr    %r2,%r5
  23         jl      .Lmemmove_reverse
  24 .Lmemmove_forward:
  25         srlg    %r0,%r4,8
  26         ltgr    %r0,%r0
  27         jz      .Lmemmove_forward_remainder
  28 .Lmemmove_forward_loop:
  29         mvc     0(256,%r1),0(%r3)
  30         la      %r1,256(%r1)
  31         la      %r3,256(%r3)
  32         brctg   %r0,.Lmemmove_forward_loop
  33 .Lmemmove_forward_remainder:
  34         larl    %r5,.Lmemmove_mvc
  35         ex      %r4,0(%r5)
  36         br      %r14
  37 .Lmemmove_reverse:
  38         ic      %r0,0(%r4,%r3)
  39         stc     %r0,0(%r4,%r1)
  40         brctg   %r4,.Lmemmove_reverse
  41         ic      %r0,0(%r4,%r3)
  42         stc     %r0,0(%r4,%r1)
  43         br      %r14
  44 .Lmemmove_mvc:
  45         mvc     0(1,%r1),0(%r3)
  46 EXPORT_SYMBOL(memmove)
  47
  48 /*
  49  * memset implementation
  50  *
  51  * This code corresponds to the C construct below. We do distinguish
  52  * between clearing (c == 0) and setting a memory array (c != 0) simply
  53  * because nearly all memset invocations in the kernel clear memory and
  54  * the xc instruction is preferred in such cases.
  55  *
  56  * void *memset(void *s, int c, size_t n)
  57  * {
  58  *      if (likely(c == 0))
  59  *              return __builtin_memset(s, 0, n);
  60  *      return __builtin_memset(s, c, n);
  61  * }
  62  */
  63 ENTRY(memset)
  64         ltgr    %r4,%r4
  65         bzr     %r14
  66         ltgr    %r3,%r3
  67         jnz     .Lmemset_fill
  68         aghi    %r4,-1
  69         srlg    %r3,%r4,8
  70         ltgr    %r3,%r3
  71         lgr     %r1,%r2
  72         jz      .Lmemset_clear_remainder
  73 .Lmemset_clear_loop:
  74         xc      0(256,%r1),0(%r1)
  75         la      %r1,256(%r1)
  76         brctg   %r3,.Lmemset_clear_loop
  77 .Lmemset_clear_remainder:
  78         larl    %r3,.Lmemset_xc
  79         ex      %r4,0(%r3)
  80         br      %r14
  81 .Lmemset_fill:
  82         stc     %r3,0(%r2)
  83         cghi    %r4,1
  84         lgr     %r1,%r2
  85         ber     %r14
  86         aghi    %r4,-2
  87         srlg    %r3,%r4,8
  88         ltgr    %r3,%r3
  89         jz      .Lmemset_fill_remainder
  90 .Lmemset_fill_loop:
  91         mvc     1(256,%r1),0(%r1)
  92         la      %r1,256(%r1)
  93         brctg   %r3,.Lmemset_fill_loop
  94 .Lmemset_fill_remainder:
  95         larl    %r3,.Lmemset_mvc
  96         ex      %r4,0(%r3)
  97         br      %r14
  98 .Lmemset_xc:
  99         xc      0(1,%r1),0(%r1)
 100 .Lmemset_mvc:
 101         mvc     1(1,%r1),0(%r1)
 102 EXPORT_SYMBOL(memset)
 103
 104 /*
 105  * memcpy implementation
 106  *
 107  * void *memcpy(void *dest, const void *src, size_t n)
 108  */
 109 ENTRY(memcpy)
 110         ltgr    %r4,%r4
 111         bzr     %r14
 112         aghi    %r4,-1
 113         srlg    %r5,%r4,8
 114         ltgr    %r5,%r5
 115         lgr     %r1,%r2
 116         jnz     .Lmemcpy_loop
 117 .Lmemcpy_remainder:
 118         larl    %r5,.Lmemcpy_mvc
 119         ex      %r4,0(%r5)
 120         br      %r14
 121 .Lmemcpy_loop:
 122         mvc     0(256,%r1),0(%r3)
 123         la      %r1,256(%r1)
 124         la      %r3,256(%r3)
 125         brctg   %r5,.Lmemcpy_loop
 126         j       .Lmemcpy_remainder
 127 .Lmemcpy_mvc:
 128         mvc     0(1,%r1),0(%r3)
 129 EXPORT_SYMBOL(memcpy)