jit_test.cpp

   1 typedef __UINT8_TYPE__ uint8_t;
   2 typedef __UINT16_TYPE__ uint16_t;
   3 typedef __UINT32_TYPE__ uint32_t;
   4 typedef __UINT64_TYPE__ uint64_t;
   5 typedef __INT8_TYPE__ int8_t;
   6 typedef __INT16_TYPE__ int16_t;
   7 typedef __INT32_TYPE__ int32_t;
   8 typedef __INT64_TYPE__ int64_t;
   9
  10 /// returns `v + inc` by jitting an addi instruction and executing it
  11 /// requires .wtext section to be writable
  12 extern "C" uint64_t jit_test(uint64_t v, int16_t inc) __attribute__((noinline, section(".wtext")));
  13 extern "C" uint64_t jit_test(uint64_t v, int16_t inc) {
  14     register uint64_t r3 asm("r3");
  15     r3 = v;
  16     uint32_t instr = 0x38630000 | (uint16_t)inc; // addi 3, 3, inc
  17     asm("mflr 5\n\t"
  18         "bl 0f\n\t"
  19         "0: mflr 4\n\t"
  20         "addi 4, 4, 1f - 0b\n\t"
  21         "stw %1, 0(4)\n\t"
  22         "dcbf 0, 4\n\t"
  23         "sync\n\t"
  24         "icbi 0, 4\n\t"
  25         "isync\n\t"
  26         "1: addi 3, 3, 0x1234\n\t"
  27         "mtlr 5"
  28         : "+b"(r3) : "b"(instr) : "r4", "r5");
  29     return r3;
  30 }
  31
  32 extern "C" uint64_t parse_hex(const char *s) __attribute__((noinline));
  33 extern "C" uint64_t parse_hex(const char *s) {
  34     uint64_t retval = 0;
  35     bool negate = *s == '-';
  36     if(*s == '-' || *s == '+')
  37         s++;
  38     if(*s == '0' && (s[1] == 'x' || s[1] == 'X'))
  39         s += 2;
  40     if(!*s)
  41         return -1;
  42     for(; *s; s++) {
  43         uint64_t digit;
  44         if(*s >= '0' && *s <= '9')
  45             digit = *s - '0';
  46         else if(*s >= 'a' && *s <= 'f')
  47             digit = *s - 'a' + 0xA;
  48         else if(*s >= 'A' && *s <= 'F')
  49             digit = *s - 'A' + 0xA;
  50         else
  51             return -1;
  52         if(retval >= 1ULL << 60)
  53             return -1;
  54         retval <<= 4;
  55         retval += digit;
  56     }
  57     return retval;
  58 }
  59
  60 extern "C" int main(int argc, char **argv) {
  61     uint64_t a = 1, b = 2;
  62     if(argc > 1)
  63         a = parse_hex(argv[1]);
  64     if(argc > 2)
  65         b = parse_hex(argv[2]);
  66     register long r3 asm("r3") = jit_test(a, b);
  67     register long r0 asm("r0") = 1; // exit
  68     asm volatile("sc" : : "r"(r0), "b"(r3));
  69 }