From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-arch@vger.kernel.org
Subject: [RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY
Date: Thu, 19 Sep 2019 17:03:16 +0200 [thread overview]
Message-ID: <20190919150808.617944343@linutronix.de> (raw)
In-Reply-To: 20190919150314.054351477@linutronix.de
Evaluating _TIF_NOHZ to decide whether to use the slow syscall entry path
is not only pointless, it's actually counterproductive:
1) Context tracking code is invoked unconditionally before that flag is
evaluated.
2) If the flag is set the slow path is invoked for nothing due to #1
Remove it.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/thread_info.h | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -133,14 +133,10 @@ struct thread_info {
#define _TIF_X32 (1 << TIF_X32)
#define _TIF_FSCHECK (1 << TIF_FSCHECK)
-/*
- * work to do in syscall_trace_enter(). Also includes TIF_NOHZ for
- * enter_from_user_mode()
- */
+/* Work to do before invoking the actual syscall. */
#define _TIF_WORK_SYSCALL_ENTRY \
(_TIF_SYSCALL_TRACE | _TIF_SYSCALL_EMU | _TIF_SYSCALL_AUDIT | \
- _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT | \
- _TIF_NOHZ)
+ _TIF_SECCOMP | _TIF_SYSCALL_TRACEPOINT)
/* flags to check in __switch_to() */
#define _TIF_WORK_CTXSW_BASE \
next prev parent reply other threads:[~2019-09-19 15:11 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 15:03 [RFC patch 00/15] entry: Provide generic implementation for host and guest entry/exit work Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 01/15] entry: Provide generic syscall entry functionality Thomas Gleixner
2019-09-20 23:38 ` Andy Lutomirski
2019-10-20 11:49 ` Thomas Gleixner
2019-09-23 9:05 ` Mike Rapoport
2019-09-19 15:03 ` Thomas Gleixner [this message]
2019-09-20 23:39 ` [RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY Andy Lutomirski
2019-09-23 20:43 ` Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 03/15] x86/entry: Use generic syscall entry function Thomas Gleixner
2019-09-20 23:41 ` Andy Lutomirski
2019-09-23 8:31 ` Peter Zijlstra
2019-09-23 8:40 ` Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 04/15] arm64/entry: " Thomas Gleixner
2019-09-20 12:21 ` Catalin Marinas
2019-09-19 15:03 ` [RFC patch 05/15] entry: Provide generic syscall exit function Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 06/15] x86/entry: Use generic syscall exit functionality Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 07/15] arm64/syscall: Remove obscure flag check Thomas Gleixner
2019-09-20 14:29 ` Catalin Marinas
2019-09-19 15:03 ` [RFC patch 08/15] arm64/syscall: Use generic syscall exit functionality Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 09/15] entry: Provide generic exit to usermode functionality Thomas Gleixner
2019-09-23 8:30 ` Peter Zijlstra
2019-09-19 15:03 ` [RFC patch 10/15] x86/entry: Move irq tracing to C code Thomas Gleixner
2019-09-23 8:47 ` Peter Zijlstra
2019-09-23 10:27 ` Thomas Gleixner
2019-09-23 11:49 ` Peter Zijlstra
2019-09-23 11:55 ` Peter Zijlstra
2019-09-23 12:10 ` Peter Zijlstra
2019-09-23 17:24 ` Andy Lutomirski
2019-09-26 2:59 ` Josh Poimboeuf
2019-09-19 15:03 ` [RFC patch 11/15] x86/entry: Use generic exit to usermode Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 12/15] arm64/entry: " Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 13/15] arm64/entry: Move FPU restore out of exit_to_usermode() loop Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 14/15] workpending: Provide infrastructure for work before entering a guest Thomas Gleixner
2019-09-19 15:40 ` Paolo Bonzini
2019-09-20 11:48 ` Thomas Gleixner
2019-09-23 18:17 ` Andy Lutomirski
2019-09-26 11:35 ` Miroslav Benes
2019-09-19 15:03 ` [RFC patch 15/15] x86/kvm: Use GENERIC_EXIT_WORKPENDING Thomas Gleixner
2019-09-19 15:40 ` Paolo Bonzini
2019-09-20 15:12 ` [RFC patch 00/15] entry: Provide generic implementation for host and guest entry/exit work Mark Rutland
2019-09-23 20:50 ` Thomas Gleixner
2019-09-23 18:18 ` Andy Lutomirski
2019-09-24 6:50 ` Christian Borntraeger
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