arch/s390/lib/mem.S

   1 /*
   2  * String handling functions.
   3  *
   4  * Copyright IBM Corp. 2012
   5  */
   6
   7 #include <linux/linkage.h>
   8
   9 /*
  10  * memset implementation
  11  *
  12  * This code corresponds to the C construct below. We do distinguish
  13  * between clearing (c == 0) and setting a memory array (c != 0) simply
  14  * because nearly all memset invocations in the kernel clear memory and
  15  * the xc instruction is preferred in such cases.
  16  *
  17  * void *memset(void *s, int c, size_t n)
  18  * {
  19  *      if (likely(c == 0))
  20  *              return __builtin_memset(s, 0, n);
  21  *      return __builtin_memset(s, c, n);
  22  * }
  23  */
  24 ENTRY(memset)
  25         ltgr    %r4,%r4
  26         bzr     %r14
  27         ltgr    %r3,%r3
  28         jnz     .Lmemset_fill
  29         aghi    %r4,-1
  30         srlg    %r3,%r4,8
  31         ltgr    %r3,%r3
  32         lgr     %r1,%r2
  33         jz      .Lmemset_clear_rest
  34 .Lmemset_clear_loop:
  35         xc      0(256,%r1),0(%r1)
  36         la      %r1,256(%r1)
  37         brctg   %r3,.Lmemset_clear_loop
  38 .Lmemset_clear_rest:
  39         larl    %r3,.Lmemset_xc
  40         ex      %r4,0(%r3)
  41         br      %r14
  42 .Lmemset_fill:
  43         stc     %r3,0(%r2)
  44         cghi    %r4,1
  45         lgr     %r1,%r2
  46         ber     %r14
  47         aghi    %r4,-2
  48         srlg    %r3,%r4,8
  49         ltgr    %r3,%r3
  50         jz      .Lmemset_fill_rest
  51 .Lmemset_fill_loop:
  52         mvc     1(256,%r1),0(%r1)
  53         la      %r1,256(%r1)
  54         brctg   %r3,.Lmemset_fill_loop
  55 .Lmemset_fill_rest:
  56         larl    %r3,.Lmemset_mvc
  57         ex      %r4,0(%r3)
  58         br      %r14
  59 .Lmemset_xc:
  60         xc      0(1,%r1),0(%r1)
  61 .Lmemset_mvc:
  62         mvc     1(1,%r1),0(%r1)
  63
  64 /*
  65  * memcpy implementation
  66  *
  67  * void *memcpy(void *dest, const void *src, size_t n)
  68  */
  69 ENTRY(memcpy)
  70         ltgr    %r4,%r4
  71         bzr     %r14
  72         aghi    %r4,-1
  73         srlg    %r5,%r4,8
  74         ltgr    %r5,%r5
  75         lgr     %r1,%r2
  76         jnz     .Lmemcpy_loop
  77 .Lmemcpy_rest:
  78         larl    %r5,.Lmemcpy_mvc
  79         ex      %r4,0(%r5)
  80         br      %r14
  81 .Lmemcpy_loop:
  82         mvc     0(256,%r1),0(%r3)
  83         la      %r1,256(%r1)
  84         la      %r3,256(%r3)
  85         brctg   %r5,.Lmemcpy_loop
  86         j       .Lmemcpy_rest
  87 .Lmemcpy_mvc:
  88         mvc     0(1,%r1),0(%r3)