--- old/usr/src/test/os-tests/tests/xsave/fpregs_xbv.c
          +++ new/usr/src/test/os-tests/tests/xsave/fpregs_xbv.c

   1    1  /*
   2    2   * This file and its contents are supplied under the terms of the
   3    3   * Common Development and Distribution License ("CDDL"), version 1.0.
   4    4   * You may only use this file in accordance with the terms of version
   5    5   * 1.0 of the CDDL.
   6    6   *
   7    7   * A full copy of the text of the CDDL should have accompanied this
   8    8   * source.  A copy of the CDDL is also available via the Internet at
   9    9   * http://www.illumos.org/license/CDDL.
  10   10   */
  11   11  
  12   12  /*
  13   13   * Copyright 2023 Oxide Computer Company
  14   14   */
  15   15  
  16   16  /*
  17   17   * In illumos#15367 we noted that on some CPUs it was possible to get the xsave
  18   18   * state into a place where it has not set components that are used for the x87
  19   19   * and XMM state. This test attempts to create those situations and then get a
  20   20   * ucontext_t to see that we actually have cleared it out. Because this behavior
  21   21   * varies from CPU to CPU (e.g. in the original case we only saw this on AMD and
  22   22   * not Intel), it can be tricky to guarantee we've recreated this.
  23   23   */
  24   24  
  25   25  #include <err.h>
  26   26  #include <stdio.h>
  27   27  #include <sys/types.h>
  28   28  #include <ucontext.h>
  29   29  #include <stdlib.h>
  30   30  
  31   31  int
  32   32  main(void)
  33   33  {
  34   34          ucontext_t ctx;
  35   35          upad128_t u, *up;
  36   36  
  37   37          u._l[0] = 0x1;
  38   38          u._l[1] = 0x2;
  39   39          u._l[2] = 0x3;
  40   40          u._l[3] = 0x4;
  41   41  
  42   42          /*
  43   43           * Load %xmm0 and then lock in the data into the pcb with a call to
  44   44           * getcontext(2) which will force an FPU save.
  45   45           */
  46   46          /* BEGIN CSTYLED */
  47   47          __asm__ __volatile__ ("movdqu %0, %%xmm0" : : "m" (u));
  48   48          __asm__ __volatile__ ("fldl %0" : : "m" (u));
  49   49          /* END CSTYLED */
  50   50          if (getcontext(&ctx) != 0) {
  51   51                  errx(EXIT_FAILURE, "TEST_FAILED: failed to get initial "
  52   52                      "ucontext");
  53   53          }
  54   54  
  55   55          /*
  56   56           * Attempt to reset the FPU at this point and then call getcontext. The
  57   57           * fninit is for the x87 part. The vzeroall covers all the higher
  58   58           * registers and this combined should reset the x87 and xmm regions back
  59   59           * to 0. It appears that on some Intel processors, the vzeroall is
  60   60           * required to get the XMM set to not be written out as opposed to just
  61   61           * doing a pxor or similar.
  62   62           */
  63   63          /* BEGIN CSTYLED */
  64   64          __asm__ __volatile__ ("fninit" : : :);
  65   65          __asm__ __volatile__ ("vzeroall" : : :);
  66   66          /* END CSTYLED */
  67   67          if (getcontext(&ctx) != 0) {
  68   68                  errx(EXIT_FAILURE, "TEST_FAILED: failed to get second "
  69   69                      "ucontext");
  70   70          }
  71   71          up = &ctx.uc_mcontext.fpregs.fp_reg_set.fpchip_state.xmm[0];
  72   72          if (up->_l[0] != 0 || up->_l[1] != 0 || up->_l[2] != 0 ||
  73   73              up->_l[3] != 0) {
  74   74                  errx(EXIT_FAILURE, "TEST FAILED: %%xmm0 was not zero, found: "
  75   75                      "0x%x 0x%x 0x%x 0x%x", up->_l[3], up->_l[2],
  76   76                      up->_l[1], up->_l[0]);
  77   77          }
  78   78  
  79   79          (void) printf("TEST PASSED: successfully got zeored %%xmm0\n");
  80   80          return (EXIT_SUCCESS);
  81   81  }

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