linux-kernel - [tip:x86/asm] x86/asm/entry/64: Simplify retint_kernel label usage, make retint_restore

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Message-ID: <tip-6ba71b7617f1fa65f19bd34f4484a0694ef9a520@git.kernel.org>
Date:	Thu, 2 Apr 2015 05:25:39 -0700
From:	tip-bot for Denys Vlasenko <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	dvlasenk@...hat.com, mingo@...nel.org, wad@...omium.org,
	fweisbec@...il.com, keescook@...omium.org,
	linux-kernel@...r.kernel.org, ast@...mgrid.com,
	torvalds@...ux-foundation.org, bp@...en8.de, tglx@...utronix.de,
	oleg@...hat.com, rostedt@...dmis.org, luto@...capital.net,
	hpa@...or.com
Subject: [tip:x86/asm] x86/asm/entry/64:
  Simplify retint_kernel label usage, make retint_restore_args label local

Commit-ID:  6ba71b7617f1fa65f19bd34f4484a0694ef9a520
Gitweb:     http://git.kernel.org/tip/6ba71b7617f1fa65f19bd34f4484a0694ef9a520
Author:     Denys Vlasenko <dvlasenk@...hat.com>
AuthorDate: Tue, 31 Mar 2015 19:00:05 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 1 Apr 2015 13:17:38 +0200

x86/asm/entry/64: Simplify retint_kernel label usage, make retint_restore_args label local

Get rid of #define obfuscation of retint_kernel in
CONFIG_PREEMPT case by defining retint_kernel label always, not
only for CONFIG_PREEMPT.

Strip retint_kernel of .global-ness (ENTRY macro) - it has no
users outside of this file.

This looks like cosmetics, but it is not:
"je LABEL" can be optimized to short jump by assember
only if LABEL is not global, for global labels jump is always
a near one with relocation.

Convert retint_restore_args to a local numeric label, making it
clearer that it is not used elsewhere in the file.

Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Will Drewry <wad@...omium.org>
Link: http://lkml.kernel.org/r/1427821211-25099-3-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/entry_64.S | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index f6e37de..1879c55 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -57,10 +57,6 @@
 	.section .entry.text, "ax"
 
 
-#ifndef CONFIG_PREEMPT
-#define retint_kernel retint_restore_args
-#endif
-
 #ifdef CONFIG_PARAVIRT
 ENTRY(native_usergs_sysret64)
 	swapgs
@@ -741,18 +737,18 @@ opportunistic_sysret_failed:
 	jmp restore_args
 
 /* Returning to kernel space */
+retint_kernel:
 #ifdef CONFIG_PREEMPT
 	/* Interrupts are off */
 	/* Check if we need preemption */
-ENTRY(retint_kernel)
 	cmpl	$0,PER_CPU_VAR(__preempt_count)
-	jnz	retint_restore_args
+	jnz	1f
 	bt	$9,EFLAGS(%rsp)	/* interrupts were off? */
-	jnc	retint_restore_args
+	jnc	1f
 	call	preempt_schedule_irq
 	jmp	exit_intr
+1:
 #endif
-retint_restore_args:
 	DISABLE_INTERRUPTS(CLBR_ANY)
 	/*
 	 * The iretq could re-enable interrupts:
--
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