none/tests/amd64/mpx.c

   1 int
   2 main (int argc, char **argv)
   3 {
   4   // Since MPX is disabled all these are just NOPS.
   5   // Some of these instructions are just random.
   6   // Once the GCC support is merged creating real test cases will be easier.
   7   // http://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler
   8
   9   // This is what ld.so does in _dl_runtime_resolve to save the bnds.
  10   asm ("bndmov %bnd0, (%rsp)");
  11   asm ("bndmov %bnd1, 16(%rsp)");
  12   asm ("bndmov %bnd2, 32(%rsp)");
  13   asm ("bndmov %bnd3, 48(%rsp)");
  14
  15   // Create a bnd, check lower and upper...
  16   asm ("bndmk (%rax,%rdx), %bnd0");
  17   asm ("bndcl (%rax,%rdi,4), %bnd0");
  18   asm ("bndcu 3(%rax,%rdi,4), %bnd0");
  19   asm ("bndcn 3(%rax,%rdi,4), %bnd0");
  20
  21   // Load bnd pointer and update...
  22   asm ("bndldx 3(%rbx,%rdx), %bnd2");
  23   asm ("bndstx %bnd2, 3(,%r12,1)");
  24
  25   // "bnd" prefixed call, return and jmp...
  26   asm ("bnd call foo\n\
  27         bnd jmp  end\n\
  28         foo: bnd ret\n\
  29         end: nop");
  30
  31   // And set the bnds back...
  32   asm ("bndmov 48(%rsp), %bnd3");
  33   asm ("bndmov 32(%rsp), %bnd2");
  34   asm ("bndmov 16(%rsp), %bnd1");
  35   asm ("bndmov (%rsp), %bnd0");
  36
  37   return 0;
  38 }