root/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 #include <asm/nospec-insn.h>
  11 
  12         GEN_BR_THUNK %r14
  13 
  14 /*
  15  * void *memmove(void *dest, const void *src, size_t n)
  16  */
  17 WEAK(memmove)
  18 ENTRY(__memmove)
  19         ltgr    %r4,%r4
  20         lgr     %r1,%r2
  21         jz      .Lmemmove_exit
  22         aghi    %r4,-1
  23         clgr    %r2,%r3
  24         jnh     .Lmemmove_forward
  25         la      %r5,1(%r4,%r3)
  26         clgr    %r2,%r5
  27         jl      .Lmemmove_reverse
  28 .Lmemmove_forward:
  29         srlg    %r0,%r4,8
  30         ltgr    %r0,%r0
  31         jz      .Lmemmove_forward_remainder
  32 .Lmemmove_forward_loop:
  33         mvc     0(256,%r1),0(%r3)
  34         la      %r1,256(%r1)
  35         la      %r3,256(%r3)
  36         brctg   %r0,.Lmemmove_forward_loop
  37 .Lmemmove_forward_remainder:
  38         larl    %r5,.Lmemmove_mvc
  39         ex      %r4,0(%r5)
  40 .Lmemmove_exit:
  41         BR_EX   %r14
  42 .Lmemmove_reverse:
  43         ic      %r0,0(%r4,%r3)
  44         stc     %r0,0(%r4,%r1)
  45         brctg   %r4,.Lmemmove_reverse
  46         ic      %r0,0(%r4,%r3)
  47         stc     %r0,0(%r4,%r1)
  48         BR_EX   %r14
  49 .Lmemmove_mvc:
  50         mvc     0(1,%r1),0(%r3)
  51 ENDPROC(__memmove)
  52 EXPORT_SYMBOL(memmove)
  53 
  54 /*
  55  * memset implementation
  56  *
  57  * This code corresponds to the C construct below. We do distinguish
  58  * between clearing (c == 0) and setting a memory array (c != 0) simply
  59  * because nearly all memset invocations in the kernel clear memory and
  60  * the xc instruction is preferred in such cases.
  61  *
  62  * void *memset(void *s, int c, size_t n)
  63  * {
  64  *      if (likely(c == 0))
  65  *              return __builtin_memset(s, 0, n);
  66  *      return __builtin_memset(s, c, n);
  67  * }
  68  */
  69 WEAK(memset)
  70 ENTRY(__memset)
  71         ltgr    %r4,%r4
  72         jz      .Lmemset_exit
  73         ltgr    %r3,%r3
  74         jnz     .Lmemset_fill
  75         aghi    %r4,-1
  76         srlg    %r3,%r4,8
  77         ltgr    %r3,%r3
  78         lgr     %r1,%r2
  79         jz      .Lmemset_clear_remainder
  80 .Lmemset_clear_loop:
  81         xc      0(256,%r1),0(%r1)
  82         la      %r1,256(%r1)
  83         brctg   %r3,.Lmemset_clear_loop
  84 .Lmemset_clear_remainder:
  85         larl    %r3,.Lmemset_xc
  86         ex      %r4,0(%r3)
  87 .Lmemset_exit:
  88         BR_EX   %r14
  89 .Lmemset_fill:
  90         cghi    %r4,1
  91         lgr     %r1,%r2
  92         je      .Lmemset_fill_exit
  93         aghi    %r4,-2
  94         srlg    %r5,%r4,8
  95         ltgr    %r5,%r5
  96         jz      .Lmemset_fill_remainder
  97 .Lmemset_fill_loop:
  98         stc     %r3,0(%r1)
  99         mvc     1(255,%r1),0(%r1)
 100         la      %r1,256(%r1)
 101         brctg   %r5,.Lmemset_fill_loop
 102 .Lmemset_fill_remainder:
 103         stc     %r3,0(%r1)
 104         larl    %r5,.Lmemset_mvc
 105         ex      %r4,0(%r5)
 106         BR_EX   %r14
 107 .Lmemset_fill_exit:
 108         stc     %r3,0(%r1)
 109         BR_EX   %r14
 110 .Lmemset_xc:
 111         xc      0(1,%r1),0(%r1)
 112 .Lmemset_mvc:
 113         mvc     1(1,%r1),0(%r1)
 114 ENDPROC(__memset)
 115 EXPORT_SYMBOL(memset)
 116 
 117 /*
 118  * memcpy implementation
 119  *
 120  * void *memcpy(void *dest, const void *src, size_t n)
 121  */
 122 WEAK(memcpy)
 123 ENTRY(__memcpy)
 124         ltgr    %r4,%r4
 125         jz      .Lmemcpy_exit
 126         aghi    %r4,-1
 127         srlg    %r5,%r4,8
 128         ltgr    %r5,%r5
 129         lgr     %r1,%r2
 130         jnz     .Lmemcpy_loop
 131 .Lmemcpy_remainder:
 132         larl    %r5,.Lmemcpy_mvc
 133         ex      %r4,0(%r5)
 134 .Lmemcpy_exit:
 135         BR_EX   %r14
 136 .Lmemcpy_loop:
 137         mvc     0(256,%r1),0(%r3)
 138         la      %r1,256(%r1)
 139         la      %r3,256(%r3)
 140         brctg   %r5,.Lmemcpy_loop
 141         j       .Lmemcpy_remainder
 142 .Lmemcpy_mvc:
 143         mvc     0(1,%r1),0(%r3)
 144 ENDPROC(__memcpy)
 145 EXPORT_SYMBOL(memcpy)
 146 
 147 /*
 148  * __memset16/32/64
 149  *
 150  * void *__memset16(uint16_t *s, uint16_t v, size_t count)
 151  * void *__memset32(uint32_t *s, uint32_t v, size_t count)
 152  * void *__memset64(uint64_t *s, uint64_t v, size_t count)
 153  */
 154 .macro __MEMSET bits,bytes,insn
 155 ENTRY(__memset\bits)
 156         ltgr    %r4,%r4
 157         jz      .L__memset_exit\bits
 158         cghi    %r4,\bytes
 159         je      .L__memset_store\bits
 160         aghi    %r4,-(\bytes+1)
 161         srlg    %r5,%r4,8
 162         ltgr    %r5,%r5
 163         lgr     %r1,%r2
 164         jz      .L__memset_remainder\bits
 165 .L__memset_loop\bits:
 166         \insn   %r3,0(%r1)
 167         mvc     \bytes(256-\bytes,%r1),0(%r1)
 168         la      %r1,256(%r1)
 169         brctg   %r5,.L__memset_loop\bits
 170 .L__memset_remainder\bits:
 171         \insn   %r3,0(%r1)
 172         larl    %r5,.L__memset_mvc\bits
 173         ex      %r4,0(%r5)
 174         BR_EX   %r14
 175 .L__memset_store\bits:
 176         \insn   %r3,0(%r2)
 177 .L__memset_exit\bits:
 178         BR_EX   %r14
 179 .L__memset_mvc\bits:
 180         mvc     \bytes(1,%r1),0(%r1)
 181 ENDPROC(__memset\bits)
 182 .endm
 183 
 184 __MEMSET 16,2,sth
 185 EXPORT_SYMBOL(__memset16)
 186 
 187 __MEMSET 32,4,st
 188 EXPORT_SYMBOL(__memset32)
 189 
 190 __MEMSET 64,8,stg
 191 EXPORT_SYMBOL(__memset64)