From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Wed, 11 Sep 2013 02:43:23 +0000 (-0700)
Subject: Merge branch 'x86/jumplabel' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=442e0973e927;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

Merge branch 'x86/jumplabel' of git://git./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
---

442e0973e9273ae8832abd70f52efde8b8326178
diff --cc arch/x86/kernel/jump_label.c
index 460f5d9ceebb,912a52812916..ee11b7dfbfbb
--- a/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();
  }