none/tests/s390x/exrl.c

   1 #include <stdio.h>
   2
   3 char buffer[] ="0123456789abcdef";
   4 char target[] ="XXXXXXXXXXXXXXXX";
   5
   6 int main(void)
   7 {
   8    unsigned long offset;
   9
  10    setbuf(stdout, NULL);
  11
  12    printf("------- Copy 10+1 bytes from buffer to target\n");
  13    printf("------- EXRL to OR in the length\n");
  14    printf("before: buffer = |%s|\n", buffer);
  15    printf("before: target = |%s|\n", target);
  16    asm volatile( "lghi 2, 10\n\t"
  17                  ".insn ril,0xc60000000000,2,1f\n\t" // exrl 2, 1f
  18                  "j    2f\n\t"
  19                  "1:\n\t"
  20                  "mvc  0(1,%0),0(%1)\n\t"
  21                  "2:\n\t"
  22                  : : "a" (target), "a" (buffer) : "1", "2", "memory");
  23    printf("after:  buffer = |%s|\n", buffer);
  24    printf("after:  target = |%s|\n", target);
  25    printf("\n");
  26
  27    printf("------- EXRL 0,... has no effect (writes out target)\n");
  28    printf("        target = |");
  29    asm volatile( "lghi 0, 0xff\n\t" // fill nonsense in r0
  30                  "lghi 2, 1\n\t"    // stdout
  31                  "lgr  3, %0\n\t"   // target
  32                  "lghi 4, %1\n\t"   // len
  33                  ".insn ril,0xc60000000000,0,1f\n\t" // exrl 0, 1f
  34                  "j    2f\n\t"
  35                  "1:\n\t"
  36                  "svc  4\n\t"       // NR_write
  37                  "2:\n\t"
  38                  : : "a" (target), "i" (sizeof target - 1)
  39                  : "0", "2", "3", "4");
  40    printf("|\n");
  41    printf("\n");
  42
  43    printf("------- EXRL to OR in the syscall number (writes out target)\n");
  44    printf("        target = |");
  45    asm volatile( "lghi 1, 4\n\t"    // NR_write
  46                  "lghi 2, 1\n\t"    // stdout
  47                  "lgr  3, %0\n\t"   // target
  48                  "lghi 4, %1\n\t"   // len
  49                  ".insn ril,0xc60000000000,1,1f\n\t" // exrl 1, 1f
  50                  "j    2f\n\t"
  51                  "1:\n\t"
  52                  "svc  0\n\t"       // changed to NR_write
  53                  "2:\n\t"
  54                  : : "a" (target), "i" (sizeof target - 1)
  55                  : "1", "2", "3", "4");
  56    printf("|\n");
  57    printf("\n");
  58
  59    printf("------- EXRL with negative offset\n");
  60    asm volatile( "j    2f\n\t"
  61                  "1:\n\t"
  62                  "mvc  2(1,%0),0(%0)\n\t"
  63                  "2:\n\t"
  64                  "lghi 1,8\n\t"
  65                  ".insn ril,0xc60000000000,1,1b\n\t" // exrl 1, 1b
  66                  : : "a" (target)
  67                  : "1", "2", "3", "4");
  68    printf("        target = |%s|\n", target);
  69    printf("\n");
  70
  71    printf("------- EXRL targeting a PC-relative instruction\n");
  72    asm volatile( "basr 1,0\n\t"
  73                  "j    2f\n\t"
  74                  "1:\n\t"
  75                  "larl 2,1b\n\t"
  76                  "2:\n\t"
  77                  ".insn ril,0xc60000000000,0,1b\n\t" // exrl 0, 1b
  78                  "sgrk %0,2,1\n\t"
  79                  : "=d" (offset) :
  80                  : "1", "2");
  81    printf("        offset = |%016lx|\n", offset);
  82    printf("\n");
  83
  84    printf("------- EXRL targeting a branch-and-link instruction\n");
  85    asm volatile( "1:\n\t"
  86                  "basr 1,0\n\t"
  87                  "lgr  2,1\n\t"
  88                  ".insn ril,0xc60000000000,0,1b\n\t" // exrl 0, 1b
  89                  "sgrk %0,1,2\n\t"
  90                  : "=&d" (offset) :
  91                  : "1", "2");
  92    printf("        offset = |%016lx|\n", offset);
  93
  94    return 0;
  95 }
  96