lldb/test/API/linux/aarch64/fpmr/main.c

   1 #include <asm/hwcap.h>
   2 #include <stdint.h>
   3 #include <sys/auxv.h>
   4
   5 #ifndef HWCAP2_FPMR
   6 #define HWCAP2_FPMR (1UL << 48)
   7 #endif
   8
   9 uint64_t get_fpmr(void) {
  10   uint64_t fpmr = 0;
  11   __asm__ volatile("mrs %0, s3_3_c4_c4_2" : "=r"(fpmr));
  12   return fpmr;
  13 }
  14
  15 void set_fpmr(uint64_t value) {
  16   __asm__ volatile("msr s3_3_c4_c4_2, %0" ::"r"(value));
  17 }
  18
  19 // Set F8S1 (bits 0-2) and LSCALE2 (bits 37-32) (to prove we treat fpmr as 64
  20 // bit).
  21 const uint64_t original_fpmr = (uint64_t)0b101010 << 32 | (uint64_t)0b101;
  22
  23 void expr_func() { set_fpmr(original_fpmr); }
  24
  25 int main(int argc, char *argv[]) {
  26   if (!(getauxval(AT_HWCAP2) & HWCAP2_FPMR))
  27     return 1;
  28
  29   // As FPMR controls a bunch of floating point options that are quite
  30   // extensive, we're not going to run any floating point ops here. Instead just
  31   // update the value from the debugger and check it from this program, and vice
  32   // versa.
  33   set_fpmr(original_fpmr);
  34
  35   // Here the debugger checks it read back the value above, then writes in a new
  36   // value. Note that the bits are flipped in the new value.
  37   uint64_t new_fpmr = get_fpmr(); // Set break point at this line.
  38   uint64_t expected_fpmr = ((uint64_t)0b010101 << 32) | (uint64_t)0b010;
  39
  40   // If the debugger failed to update the value, exit uncleanly.
  41   // This also allows you to run this program standalone to create a core file.
  42   if (new_fpmr != expected_fpmr)
  43     __builtin_trap();
  44
  45   return 0;
  46 }