linux-kernel - [tip:x86/asm] x86/entry: Only allocate space for tss_struct::SYSENTER

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Message-ID: <tip-6dcc94149d605908a7c0c4cf2085340637aac86d@git.kernel.org>
Date:	Thu, 10 Mar 2016 03:03:28 -0800
From:	tip-bot for Andy Lutomirski <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
	tglx@...utronix.de, luto@...nel.org, oleg@...hat.com,
	mingo@...nel.org, bp@...en8.de, luto@...capital.net, hpa@...or.com,
	peterz@...radead.org, dvlasenk@...hat.com,
	andrew.cooper3@...rix.com, brgerst@...il.com
Subject: [tip:x86/asm] x86/entry: Only allocate space for
 tss_struct::SYSENTER_stack if needed

Commit-ID:  6dcc94149d605908a7c0c4cf2085340637aac86d
Gitweb:     http://git.kernel.org/tip/6dcc94149d605908a7c0c4cf2085340637aac86d
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Wed, 9 Mar 2016 19:00:31 -0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 10 Mar 2016 09:48:14 +0100

x86/entry: Only allocate space for tss_struct::SYSENTER_stack if needed

The SYSENTER stack is only used on 32-bit kernels.  Remove it on 64-bit kernels.

( We may end up using it down the road on 64-bit kernels. If so,
  we'll re-enable it for CONFIG_IA32_EMULATION. )

Signed-off-by: Andy Lutomirski <luto@...nel.org>
Cc: Andrew Cooper <andrew.cooper3@...rix.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/9dbd18429f9ff61a76b6eda97a9ea20510b9f6ba.1457578375.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/processor.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ecb4103..7cd01b7 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -297,10 +297,12 @@ struct tss_struct {
 	 */
 	unsigned long		io_bitmap[IO_BITMAP_LONGS + 1];
 
+#ifdef CONFIG_X86_32
 	/*
 	 * Space for the temporary SYSENTER stack:
 	 */
 	unsigned long		SYSENTER_stack[64];
+#endif
 
 } ____cacheline_aligned;