[tip:x86/asm] x86/asm: Remove thread_info.sysenter_return

[tip-bot for Andy Lutomirski <tipbot@zytor.com>]

Commit-ID:  487e3bf4f77699160aa81a414200060a78a67c3d
Gitweb:     http://git.kernel.org/tip/487e3bf4f77699160aa81a414200060a78a67c3d
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Mon, 5 Oct 2015 17:48:16 -0700
Committer:  Ingo Molnar <mingo@kernel.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@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
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: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/r/f08cc0cff30201afe9bb565c47134c0a6c1a96a2.1444091585.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.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