linux-kernel - [tip:x86/asm] x86/asm: Remove thread_info.sysenter

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Message-ID: <tip-487e3bf4f77699160aa81a414200060a78a67c3d@git.kernel.org>
Date:	Fri, 9 Oct 2015 06:13:25 -0700
From:	tip-bot for Andy Lutomirski <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	luto@...capital.net, bp@...en8.de, peterz@...radead.org,
	dvlasenk@...hat.com, luto@...nel.org, mingo@...nel.org,
	hpa@...or.com, linux-kernel@...r.kernel.org, tglx@...utronix.de,
	torvalds@...ux-foundation.org, brgerst@...il.com
Subject: [tip:x86/asm] x86/asm: Remove thread_info.sysenter_return

Commit-ID:  487e3bf4f77699160aa81a414200060a78a67c3d
Gitweb:     http://git.kernel.org/tip/487e3bf4f77699160aa81a414200060a78a67c3d
Author:     Andy Lutomirski <luto@...nel.org>
AuthorDate: Mon, 5 Oct 2015 17:48:16 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 9 Oct 2015 09:41:11 +0200

x86/asm: Remove thread_info.sysenter_return

It's no longer needed.

We could reinstate something like it as an optimization, which
would remove two cachelines from the fast syscall entry working
set.  I benchmarked it, and it makes no difference whatsoever to
the performance of cache-hot compat syscalls on Sandy Bridge.

Signed-off-by: Andy Lutomirski <luto@...nel.org>
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: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Link: http://lkml.kernel.org/r/f08cc0cff30201afe9bb565c47134c0a6c1a96a2.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/thread_info.h | 1 -
 arch/x86/kernel/asm-offsets.c      | 3 ---
 2 files changed, 4 deletions(-)

diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index 8afdc3e..a1ecd21 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -59,7 +59,6 @@ struct thread_info {
 	__u32			cpu;		/* current CPU */
 	int			saved_preempt_count;
 	mm_segment_t		addr_limit;
-	void __user		*sysenter_return;
 	unsigned int		sig_on_uaccess_error:1;
 	unsigned int		uaccess_err:1;	/* uaccess failed */
 };
diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index 8e3d22a1..95a18e2 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -54,9 +54,6 @@ void common(void) {
 	OFFSET(IA32_SIGCONTEXT_ip, sigcontext_ia32, ip);
 
 	BLANK();
-	OFFSET(TI_sysenter_return, thread_info, sysenter_return);
-
-	BLANK();
 	OFFSET(IA32_RT_SIGFRAME_sigcontext, rt_sigframe_ia32, uc.uc_mcontext);
 #endif
 
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