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

@@ -19,11 +19,11 @@
  * CDDL HEADER END
  */
 
 /*
  * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright 2017, Joyent, Inc.
+ * Copyright 2020 Joyent, Inc.
  */
 /*
  * Copyright (c) 2010, Intel Corporation.
  * All rights reserved.
  */

@@ -188,10 +188,16 @@
 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

@@ -1452,6 +1458,40 @@
 
 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 */
+        }
 }