From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5FDEA1ACEAF for ; Thu, 11 Sep 2025 16:08:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757606912; cv=none; b=CWyWPuu+H7SYSb+zlnw9WRylUJbYp5AnLdJ20FUNwJNbKf81gFceyfG3Orlnri0XhE5Sqbj4l4aSJHEJKF5d4spYbLDSjI8BeDeQz1PkBMqnZeGFbKY6SKq4Vk3sQZZExkVRtURBpsR+wTTZMyctLSMMTGXMpxAOXnDPhnOeeME= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757606912; c=relaxed/simple; bh=ALtwD3nkFpsn21nflnW8WCMBoCvlqLFjp+n+CDq8Bmw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=FIzvnvvm6foPnOgneTfK7sgW6vD5AvOHD6PsctqriGKUggyUB9qVuA2dxzeyiajZRlJxTKzCdWYPAgWxqVuY3ouUoyuiEPF61/ULvmLUfNbjwQqBfP3Tc3CchVHhTYv7l+iW9VPgvKPxpEXGJADmvW4bB/nUhv0zD+us5fDm2Ts= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=kCy1I/4p; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=/b8oBpzf; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="kCy1I/4p"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="/b8oBpzf" From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1757606909; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rtftTCr0uyk0T0ztP7XLXAUwMAADbprFx8itfTXteEE=; b=kCy1I/4puobbmlTUbVi+NM+ZYA68sonMMx+uu557/2pb3effPuwXdvdZYa/YvVOk/H70pV uL/c1a7iahcQyyd2ZLmoy0GgKBaFYP2sRWOro4a1lkjWbuACJ9YA2VXS7qn46sfFMDG9z1 H7JJlHIY3eg1c+PJFIKJAopZyl34vlUhAzJLUw7NI+44gTOdUjUofimFYPK4YrQfUYGc3M ZLQ92Ib/B75/3im1YsubJBbTTMcjOfqhtoEXSAwpQ/FxH2xEKZytW20Y8YPipb1IKZW4pz f0gGczqBfeNMeGxV65lJLVWjCFG8djJDWpcOMZH0AMApClR/ypom1yTNroqTog== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1757606909; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=rtftTCr0uyk0T0ztP7XLXAUwMAADbprFx8itfTXteEE=; b=/b8oBpzfeKPXwSqCktu0sLKkl1kXAL+oRsUHzYVHkzCxk5k0poUMvvdvQEeBc7DZU/Spgk ZplaIVN0VCSC28Ag== To: Mathieu Desnoyers , LKML Cc: Michael Jeanson , Jens Axboe , Peter Zijlstra , "Paul E. McKenney" , Boqun Feng , Paolo Bonzini , Sean Christopherson , Wei Liu , Dexuan Cui , x86@kernel.org, Arnd Bergmann , Heiko Carstens , Christian Borntraeger , Sven Schnelle , Huacai Chen , Paul Walmsley , Palmer Dabbelt Subject: Re: [patch V4 27/36] rseq: Implement fast path for exit to user In-Reply-To: References: <20250908212737.353775467@linutronix.de> <20250908212926.993963056@linutronix.de> Date: Thu, 11 Sep 2025 18:08:28 +0200 Message-ID: <87y0qlq8eb.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Thu, Sep 11 2025 at 10:27, Mathieu Desnoyers wrote: > On 2025-09-08 17:32, Thomas Gleixner wrote: >> The initial decision to invoke any of this is based on two flags in the >> event struct: @has_rseq and @sched_switch. The decision is in pseudo ASM: >> >> load tsk::event::has_rseq >> and tsk::event::sched_switch > > I suspect that my earlier comment about has_rseq and AND applies here > as well. We could probably remove the has_rseq load and the AND > altogether and just load sched_switch for the conditional branch ? Same comment as before.