Merge branch 'x86/jumplabel' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 jumplabel changes from Peter Anvin:
 "One more x86 tree for this merge window.  This tree improves the
  handling of jump labels, so that most of the time we don't have to do
  a massive initial patching run.

  Furthermore, we will error out of the jump label is not what is
  expected, eg if it has been corrupted or tampered with"

* 'x86/jumplabel' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/jump-label: Show where and what was wrong on errors
  x86/jump-label: Add safety checks to jump label conversions
  x86/jump-label: Do not bother updating nops if they are correct
  x86/jump-label: Use best default nops for inital jump label calls

diff --cc arch/x86/kernel/jump_label.c
index 460f5d9,912a528..ee11b7d
--- 1/arch/x86/kernel/jump_label.c
--- 2/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@@ -34,22 -55,28 +55,40 @@@ static void __jump_label_transform(stru
                code.jump = 0xe9;
                code.offset = entry->target -
                                (entry->code + JUMP_LABEL_NOP_SIZE);
-       } else
+       } else {
+               /*
+                * We are disabling this jump label. If it is not what
+                * we think it is, then something must have gone wrong.
+                * If this is the first initialization call, then we
+                * are converting the default nop to the ideal nop.
+                */
+               if (init) {
+                       const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
+                       if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))
+                               bug_at((void *)entry->code, __LINE__);
+               } else {
+                       code.jump = 0xe9;
+                       code.offset = entry->target -
+                               (entry->code + JUMP_LABEL_NOP_SIZE);
+                       if (unlikely(memcmp((void *)entry->code, &code, 5) != 0))
+                               bug_at((void *)entry->code, __LINE__);
+               }
                memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
+       }
  
 -      (*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
 +      /*
 +       * Make text_poke_bp() a default fallback poker.
 +       *
 +       * At the time the change is being done, just ignore whether we
 +       * are doing nop -> jump or jump -> nop transition, and assume
 +       * always nop being the 'currently valid' instruction
 +       *
 +       */
 +      if (poker)
 +              (*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
 +      else
 +              text_poke_bp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE,
 +                           (void *)entry->code + JUMP_LABEL_NOP_SIZE);
  }
  
  void arch_jump_label_transform(struct jump_entry *entry,
@@@ -57,7 -84,7 +96,7 @@@
  {
        get_online_cpus();
        mutex_lock(&text_mutex);
-       __jump_label_transform(entry, type, NULL);
 -      __jump_label_transform(entry, type, text_poke_smp, 0);
++      __jump_label_transform(entry, type, NULL, 0);
        mutex_unlock(&text_mutex);
        put_online_cpus();
  }