1 /*
   2  * This file and its contents are supplied under the terms of the
   3  * Common Development and Distribution License ("CDDL"), version 1.0.
   4  * You may only use this file in accordance with the terms of version
   5  * 1.0 of the CDDL.
   6  *
   7  * A full copy of the text of the CDDL should have accompanied this
   8  * source.  A copy of the CDDL is also available via the Internet at
   9  * http://www.illumos.org/license/CDDL.
  10  */
  11 
  12 /*
  13  * Copyright 2023 Oxide Computer Company
  14  */
  15 
  16 /*
  17  * This is a program that is meant to be used as a target for libproc and mdb.
  18  * It uses a CLI-based seed and sets its FPU to a set of known values. After
  19  * that, we call a function that can be used as a no-op target to dump the FPU
  20  * state, attempting to minimize the number of instructions inbetween
  21  * operations. We use the 'yield(2)' system call and library function in libc
  22  * for that as it's something that'll not really do much and it is very unlikely
  23  * the compiler will use the FPU between function calls.
  24  */
  25 
  26 #include <err.h>
  27 #include <stdlib.h>
  28 #include <unistd.h>
  29 #include <errno.h>
  30 
  31 #include "xsave_util.h"
  32 
  33 static xsu_fpu_t fpu;
  34 
  35 int
  36 main(int argc, char *argv[])
  37 {
  38         uint32_t hwsup;
  39         char *eptr;
  40         unsigned long ul;
  41 
  42         if (argc != 2) {
  43                 errx(EXIT_FAILURE, "missing required seed");
  44         }
  45 
  46         errno = 0;
  47         ul = strtoul(argv[1], &eptr, 0);
  48         if (errno != 0 || *eptr != '\0') {
  49                 errx(EXIT_FAILURE, "seed value is bad: %s", argv[3]);
  50         }
  51 
  52         hwsup = xsu_hwsupport();
  53         xsu_fill(&fpu, hwsup, (uint32_t)ul);
  54         xsu_setfpu(&fpu, hwsup);
  55 
  56         yield();
  57         return (EXIT_SUCCESS);
  58 }