none/tests/s390x/ex.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("------- EX to OR in the length\n");
  14    printf("before: buffer = |%s|\n", buffer);
  15    printf("before: target = |%s|\n", target);
  16    asm volatile( "larl 1, 1f\n\t"
  17                  "lghi 2, 10\n\t"
  18                  "ex   2, 0(1)\n\t"
  19                  "j    2f\n\t"
  20                  "1:\n\t"
  21                  "mvc  0(1,%0),0(%1)\n\t"
  22                  "2:\n\t"
  23                  : : "a" (target), "a" (buffer): "1", "2", "memory");
  24    printf("after:  buffer = |%s|\n", buffer);
  25    printf("after:  target = |%s|\n", target);
  26    printf("\n");
  27
  28    printf("------- EX 0,... has no effect (writes out target)\n");
  29    printf("        target = |");
  30    asm volatile( "lghi 0, 0xff\n\t" // fill nonsense in r0
  31                  "larl 1, 1f\n\t"
  32                  "lghi 2, 1\n\t"    // stdout
  33                  "lgr  3, %0\n\t"   // target
  34                  "lghi 4, %1\n\t"   // len
  35                  "ex   0, 0(1)\n\t"
  36                  "j    2f\n\t"
  37                  "1:\n\t"
  38                  "svc  4\n\t"
  39                  "2:\n\t"
  40                  : : "a" (target), "i" (sizeof target - 1)
  41                  : "0", "1", "2", "3", "4");
  42    printf("|\n");
  43    printf("\n");
  44
  45    printf("------- EX to OR in the syscall number (writes out target)\n");
  46    printf("        target = |");
  47    asm volatile( "lghi 5, 4\n\t"    // NR_write
  48                  "larl 1, 1f\n\t"
  49                  "lghi 2, 1\n\t"    // stdout
  50                  "lgr  3, %0\n\t"   // target
  51                  "lghi 4, %1\n\t"   // len
  52                  "ex   5, 0(1)\n\t"
  53                  "j    2f\n\t"
  54                  "1:\n\t"
  55                  "svc  0\n\t"       // changed to NR_write
  56                  "2:\n\t"
  57                  : : "a" (target), "i" (sizeof target - 1)
  58                  : "1", "2", "3", "4", "5");
  59    printf("|\n");
  60    printf("\n");
  61
  62    printf("------- EX targeting a PC-relative instruction\n");
  63    asm volatile( "1:\n\t"
  64                  "larl 1,1b\n\t"
  65                  "lgr  2,1\n\t"
  66                  "ex   0, 0(2)\n\t"
  67                  "sgrk %0,1,2\n\t"
  68                  : "=d" (offset) :
  69                  : "1", "2");
  70    printf("        offset = |%016lx|\n", offset);
  71    printf("\n");
  72
  73    printf("------- EX targeting a branch-and-link instruction\n");
  74    asm volatile( "larl  1,1f\n\t"
  75                  "ex    0, 0(1)\n\t"
  76                  ".insn e,0x0000\n\t"
  77                  "1:\n\t"
  78                  "brasl 2,2f\n\t"
  79                  "2:\n\t"
  80                  "sgrk %0,1,2\n\t"
  81                  : "=&d" (offset) :
  82                  : "1", "2");
  83    printf("        offset = |%016lx|\n", offset);
  84    printf("\n");
  85
  86    return 0;
  87 }
  88