8956 Implement KPTI
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Reviewed by: Robert Mustacchi <rm@joyent.com>

@@ -22,10 +22,12 @@
  * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 /*
  * Copyright (c) 2010, Intel Corporation.
  * All rights reserved.
+ *
+ * Copyright 2018 Joyent, Inc.
  */
         
 #include <sys/asm_linkage.h>
 #include <sys/asm_misc.h>
 #include <sys/regset.h>

@@ -324,11 +326,11 @@
 
         /*
          * Complete the rest of the setup and call mp_startup().
          */
         movq    %gs:CPU_THREAD, %rax    /* get thread ptr */
-        call    *T_PC(%rax)             /* call mp_startup */
+        call    *T_PC(%rax)             /* call mp_startup_boot */
         /* not reached */
         int     $20                     /* whoops, returned somehow! */
 
         SET_SIZE(real_mode_start_cpu)
 

@@ -500,11 +502,11 @@
         or      $(CR0_MP|CR0_NE), %edx
         mov     %edx, %cr0              /* set machine status word */
 
         /*
          * Before going any farther, enable usage of page table NX bit if 
-         * that's how our page tables are set up.
+         * that's how our page tables are set up.  (PCIDE is enabled later on).
          */
         bt      $X86FSET_NX, x86_featureset
         jnc     1f
         movl    %cr4, %ecx
         andl    $CR4_PAE, %ecx