9059 Simplify SMAP relocations with krtld
Portions contributed by: John Levon <john.levon@joyent.com>

*** 19,29 ****
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2017, Joyent, Inc.
   */
  /*
   * Copyright (c) 2010, Intel Corporation.
   * All rights reserved.
   */
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
!  * Copyright 2020 Joyent, Inc.
   */
  /*
   * Copyright (c) 2010, Intel Corporation.
   * All rights reserved.
   */
*** 188,197 ****
--- 188,203 ----
  extern void pm_cfb_rele(void);
  
  extern fastboot_info_t newkernel;
  
  /*
+  * Instructions to enable or disable SMAP, respectively.
+  */
+ static const uint8_t clac_instr[3] = { 0x0f, 0x01, 0xca };
+ static const uint8_t stac_instr[3] = { 0x0f, 0x01, 0xcb };
+ 
+ /*
   * Machine dependent code to reboot.
   * "mdep" is interpreted as a character pointer; if non-null, it is a pointer
   * to a string to be used as the argument string when rebooting.
   *
   * "invoke_cb" is a boolean. It is set to true when mdboot() can safely
*** 1452,1457 ****
--- 1458,1497 ----
  
  void
  plat_dr_disable_capability(uint64_t features)
  {
          atomic_and_64(&plat_dr_options, ~features);
+ }
+ 
+ /*
+  * If SMAP is supported, look through hi_calls and inline
+  * calls to smap_enable() to clac and smap_disable() to stac.
+  */
+ void
+ hotinline_smap(hotinline_desc_t *hid)
+ {
+         if (is_x86_feature(x86_featureset, X86FSET_SMAP) == B_FALSE)
+                 return;
+ 
+         if (strcmp(hid->hid_symname, "smap_enable") == 0) {
+                 bcopy(clac_instr, (void *)hid->hid_instr_offset,
+                     sizeof (clac_instr));
+         } else if (strcmp(hid->hid_symname, "smap_disable") == 0) {
+                 bcopy(stac_instr, (void *)hid->hid_instr_offset,
+                     sizeof (stac_instr));
+         }
+ }
+ 
+ /*
+  * Loop through hi_calls and hand off the inlining to
+  * the appropriate calls.
+  */
+ void
+ do_hotinlines(struct module *mp)
+ {
+         for (hotinline_desc_t *hid = mp->hi_calls; hid != NULL;
+             hid = hid->hid_next) {
+ #if !defined(__xpv)
+                 hotinline_smap(hid);
+ #endif  /* __xpv */
+         }
  }