From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (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 0CC9A2550D4 for ; Mon, 12 May 2025 06:14:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747030484; cv=none; b=SMwWEK2WzIwc7IHNdTYaJXhHmTu/UzvTHofvz6V0swEmnD/0I3qg2VhqmEaiqrGbJJe9ea37eu3OoK22AScBk8uMci4ndDR+t1j9igwdsT85zhKD+nNusKXKcQsYw+bbMpX3HkM4iZ8IkesA5UzRlymKIM+xT1eWu7JoB6HeZ0E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747030484; c=relaxed/simple; bh=6VGOHiXeKIYDYPQCVUYnbq52DEqZeDk54QiYjrq8AmM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gOB9VYq+iemcAo1KJNMAWIBnM+a/v+sNtmZmG7h/IQDX16naUmWk7t78Qcde/FarXlfqC2AwWWErC3gbK3xWfnPqI9lIY78QJ1JWftTomJHrnoyz1TVQyWSijLUWMzMkYSWm3upqcMadgU3FRhxUggqKRNMRSzf1ejX2hZl8kK4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=Yh2/Ei4h; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="Yh2/Ei4h" Received: from [192.168.7.202] ([71.202.166.45]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 54C6Diur1524315 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NO); Sun, 11 May 2025 23:13:45 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 54C6Diur1524315 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2025042001; t=1747030426; bh=OdItbHs5YyBIEsuHQA8Bv8vb+bsaWnlWSRLvKjXyLDE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=Yh2/Ei4ha8TuYH0PLwXMFYNI2wsdwbs6QvJhuVjPjOhKhW++rea92KACWsFwZshCY ruXE0awuXKE01wfuJye6wUJpqf5Voy5MTrCiF8f6q84LWRZEomL/7fR7EhGmTk7EMk 2QLr7FRtlNEvypTp805qM068vqvBl5Jza8FteMnKZw8ilJKUsKk7RnDDPKCkPU7MNY 1wOX+mc/vI3Vz0T97TcX127fUIqJ0UBhy8crh8uHIylQqlt1nTrVqGkHIagRp9/aWN rWkmdu+6pNJTr6qYybU7vkMl9agHr/V8rtduYed+m8WGdXzWKjADQV4ET1RV+t2jMg tunK8P9jizPkg== Message-ID: <8925f277-a173-47c4-95e3-ed6234a45043@zytor.com> Date: Sun, 11 May 2025 23:13:44 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 3/3] x86: Zap TOP_OF_KERNEL_STACK_PADDING on x86_64 To: "H. Peter Anvin" , Brian Gerst Cc: linux-kernel@vger.kernel.org, luto@kernel.org, tglx@linutronix.de, mingo@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, peterz@infradead.org References: <20250319071009.1390984-1-xin@zytor.com> <20250319071009.1390984-4-xin@zytor.com> <8b920da6-0c9a-43b4-bd50-79c057a01932@zytor.com> <1106B557-4AA2-410F-A990-C0C3BB7E675B@zytor.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; keydata= xsDNBGUPz1cBDACS/9yOJGojBFPxFt0OfTWuMl0uSgpwk37uRrFPTTLw4BaxhlFL0bjs6q+0 2OfG34R+a0ZCuj5c9vggUMoOLdDyA7yPVAJU0OX6lqpg6z/kyQg3t4jvajG6aCgwSDx5Kzg5 Rj3AXl8k2wb0jdqRB4RvaOPFiHNGgXCs5Pkux/qr0laeFIpzMKMootGa4kfURgPhRzUaM1vy bsMsL8vpJtGUmitrSqe5dVNBH00whLtPFM7IbzKURPUOkRRiusFAsw0a1ztCgoFczq6VfAVu raTye0L/VXwZd+aGi401V2tLsAHxxckRi9p3mc0jExPc60joK+aZPy6amwSCy5kAJ/AboYtY VmKIGKx1yx8POy6m+1lZ8C0q9b8eJ8kWPAR78PgT37FQWKYS1uAroG2wLdK7FiIEpPhCD+zH wlslo2ETbdKjrLIPNehQCOWrT32k8vFNEMLP5G/mmjfNj5sEf3IOKgMTMVl9AFjsINLHcxEQ 6T8nGbX/n3msP6A36FDfdSEAEQEAAc0WWGluIExpIDx4aW5Aenl0b3IuY29tPsLBDQQTAQgA NxYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89XBQkFo5qAAhsDBAsJCAcFFQgJCgsFFgID AQAACgkQa70OVx2uN1HUpgv/cM2fsFCQodLArMTX5nt9yqAWgA5t1srri6EgS8W3F+3Kitge tYTBKu6j5BXuXaX3vyfCm+zajDJN77JHuYnpcKKr13VcZi1Swv6Jx1u0II8DOmoDYLb1Q2ZW v83W55fOWJ2g72x/UjVJBQ0sVjAngazU3ckc0TeNQlkcpSVGa/qBIHLfZraWtdrNAQT4A1fa sWGuJrChBFhtKbYXbUCu9AoYmmbQnsx2EWoJy3h7OjtfFapJbPZql+no5AJ3Mk9eE5oWyLH+ QWqtOeJM7kKvn/dBudokFSNhDUw06e7EoVPSJyUIMbYtUO7g2+Atu44G/EPP0yV0J4lRO6EA wYRXff7+I1jIWEHpj5EFVYO6SmBg7zF2illHEW31JAPtdDLDHYcZDfS41caEKOQIPsdzQkaQ oW2hchcjcMPAfyhhRzUpVHLPxLCetP8vrVhTvnaZUo0xaVYb3+wjP+D5j/3+hwblu2agPsaE vgVbZ8Fx3TUxUPCAdr/p73DGg57oHjgezsDNBGUPz1gBDAD4Mg7hMFRQqlzotcNSxatlAQNL MadLfUTFz8wUUa21LPLrHBkUwm8RujehJrzcVbPYwPXIO0uyL/F///CogMNx7Iwo6by43KOy g89wVFhyy237EY76j1lVfLzcMYmjBoTH95fJC/lVb5Whxil6KjSN/R/y3jfG1dPXfwAuZ/4N cMoOslWkfZKJeEut5aZTRepKKF54T5r49H9F7OFLyxrC/uI9UDttWqMxcWyCkHh0v1Di8176 jjYRNTrGEfYfGxSp+3jYL3PoNceIMkqM9haXjjGl0W1B4BidK1LVYBNov0rTEzyr0a1riUrp Qk+6z/LHxCM9lFFXnqH7KWeToTOPQebD2B/Ah5CZlft41i8L6LOF/LCuDBuYlu/fI2nuCc8d m4wwtkou1Y/kIwbEsE/6RQwRXUZhzO6llfoN96Fczr/RwvPIK5SVMixqWq4QGFAyK0m/1ap4 bhIRrdCLVQcgU4glo17vqfEaRcTW5SgX+pGs4KIPPBE5J/ABD6pBnUUAEQEAAcLA/AQYAQgA JhYhBIUq/WFSDTiOvUIqv2u9DlcdrjdRBQJlD89ZBQkFo5qAAhsMAAoJEGu9DlcdrjdR4C0L /RcjolEjoZW8VsyxWtXazQPnaRvzZ4vhmGOsCPr2BPtMlSwDzTlri8BBG1/3t/DNK4JLuwEj OAIE3fkkm+UG4Kjud6aNeraDI52DRVCSx6xff3bjmJsJJMb12mWglN6LjdF6K+PE+OTJUh2F dOhslN5C2kgl0dvUuevwMgQF3IljLmi/6APKYJHjkJpu1E6luZec/lRbetHuNFtbh3xgFIJx 2RpgVDP4xB3f8r0I+y6ua+p7fgOjDLyoFjubRGed0Be45JJQEn7A3CSb6Xu7NYobnxfkwAGZ Q81a2XtvNS7Aj6NWVoOQB5KbM4yosO5+Me1V1SkX2jlnn26JPEvbV3KRFcwV5RnDxm4OQTSk PYbAkjBbm+tuJ/Sm+5Yp5T/BnKz21FoCS8uvTiziHj2H7Cuekn6F8EYhegONm+RVg3vikOpn gao85i4HwQTK9/D1wgJIQkdwWXVMZ6q/OALaBp82vQ2U9sjTyFXgDjglgh00VRAHP7u1Rcu4 l75w1xInsg== In-Reply-To: <1106B557-4AA2-410F-A990-C0C3BB7E675B@zytor.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/21/2025 1:14 AM, H. Peter Anvin wrote: > On March 20, 2025 10:47:25 PM PDT, Xin Li wrote: >> On 3/19/2025 12:17 PM, Brian Gerst wrote: >>> I'm not sure it's worth fully removing TOP_OF_KERNEL_STACK_PADDING for >>> 64-bit if it results in needing separate definitions of >>> task_top_of_stack(). Leaving it at zero is fine. The other changes >>> are fine though. >> >> Let's leave it to x86 maintainers ;-) >> >> But to me, TOP_OF_KERNEL_STACK_PADDING no longer makes sense on 64-bit, >> and it makes it simpler to remove it. On the other side, 32-bit is to >> be zapped... >> >> Thanks! >> Xin >> > > For what it's worth, it was there as 0 before the FRED changes, so ... > Okay, I will drop this patch and send the patch set as v4. Thanks! Xin