From: Dominik Brodowski <linux@dominikbrodowski.net>
Date: Tue, 6 Mar 2018 21:18:09 +0000 (+0100)
Subject: x86/entry/64/compat: Save one instruction in entry_INT80_compat()
X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=91c5f0de64a226e0d9c558b26ef7c2655ef31cca;p=openwrt%2Fstaging%2Fblogic.git

x86/entry/64/compat: Save one instruction in entry_INT80_compat()

As %rdi is never user except in the following push, there is no
need to restore %rdi to the original value.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: luto@amacapital.net
Cc: viro@zeniv.linux.org.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index ff61b7bb750b..08425c42f8b7 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -363,9 +363,7 @@ ENTRY(entry_INT80_compat)
 	pushq	2*8(%rdi)		/* regs->ip */
 	pushq	1*8(%rdi)		/* regs->orig_ax */
 
-	movq	(%rdi), %rdi		/* restore %rdi */
-
-	pushq	%rdi			/* pt_regs->di */
+	pushq	(%rdi)			/* pt_regs->di */
 	pushq	%rsi			/* pt_regs->si */
 	pushq	%rdx			/* pt_regs->dx */
 	pushq	%rcx			/* pt_regs->cx */