linux-kernel - [PATCH 4.14 055/159] x86/entry/64: Shorten TEST instructions

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Date:   Fri, 22 Dec 2017 09:45:40 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Andy Lutomirski <luto@...nel.org>,
        Brian Gerst <brgerst@...il.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.14 055/159] x86/entry/64: Shorten TEST instructions

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Borislav Petkov <bp@...e.de>

commit 1e4c4f610f774df6088d7c065b2dd4d22adba698 upstream.

Convert TESTL to TESTB and save 3 bytes per callsite.

No functionality change.

Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20171102120926.4srwerqrr7g72e2k@pd.tnic
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/entry/entry_64.S |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -621,7 +621,7 @@ GLOBAL(retint_user)
 GLOBAL(swapgs_restore_regs_and_return_to_usermode)
 #ifdef CONFIG_DEBUG_ENTRY
 	/* Assert that pt_regs indicates user mode. */
-	testl	$3, CS(%rsp)
+	testb	$3, CS(%rsp)
 	jnz	1f
 	ud2
 1:
@@ -654,7 +654,7 @@ retint_kernel:
 GLOBAL(restore_regs_and_return_to_kernel)
 #ifdef CONFIG_DEBUG_ENTRY
 	/* Assert that pt_regs indicates kernel mode. */
-	testl	$3, CS(%rsp)
+	testb	$3, CS(%rsp)
 	jz	1f
 	ud2
 1: