From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f53.google.com (mail-ed1-f53.google.com [209.85.208.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 37DDE263899; Tue, 8 Jul 2025 09:40:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751967603; cv=none; b=n8ryW0Uwh0Hz5fX6MOIMhESFxtWSEfCI+X5QgOpxc0cbGKsXAyt1zv5EfKU6+J9RVWhNqWB56+A8ySjBz0LrZLNhUPydoDCYDvnBC2MRL/A5RFgqf9fh6S+IvAzfqy/c7l7ztFenHFkuQTw90niWfiKGIKBtv2gy9D2cQ+BaNsY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751967603; c=relaxed/simple; bh=/juqDHVkSFYcxrJeW4anGnUPTRAjelc4Xxu89KkV+6I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bWqy0sW7/XCegv25dvhDOWM1ZGlMf72MKXBiKGr5cxdoNhac5Ag6z8K/mewW8IxzWfverkApKHYSQXIh2hwjek/x4/hXjWSxO9M7aCV4wx619OUxk6MocmPb7rFbuYf2+kJf+hdy3rEaHHbqWsPX2lSzJ3QohnvJPDf9KSPyorc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org; spf=pass smtp.mailfrom=gmail.com; arc=none smtp.client-ip=209.85.208.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=debian.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ed1-f53.google.com with SMTP id 4fb4d7f45d1cf-6088d856c6eso8052381a12.0; Tue, 08 Jul 2025 02:40:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751967600; x=1752572400; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=zDGRwzwOvCrWWFQfPfpra9qYK3fJVDbD/wSIIQxXnMM=; b=jbKUGsMNN8fnLoFaNadN1v3IHHlvLV7qSP3Gh0F2p55jG+DpDNPK7SnXyC4UnSIoK+ Ga8pNl4/kc/+hwpgVZdmB7c4FmeYTzuCjrvJov0pl2d7cAHC/iJqfv9VRPKny2Vi0/Q0 f0f8Ce7/UXxgAcxpevJniTE74fydYvgAKAziMtiSLiOXFu4Ph8/hxJJeSvynk+j+Pz3J elSMiRNPZmtnq0r1jEhezK0AmY5+UqltwohZaSw+mRJMt4TcdyV9duEkYK8R+DQDKQR+ /Lq61bIBRjWB3N3KavLbt2+bleeIyy4MUlh7uJNiWzGIqpDl8toaKPSCPzJl2SKtdgMT SgxQ== X-Forwarded-Encrypted: i=1; AJvYcCUm2hisHZPt1T8lcD5f3gNIJFdzDcAAAhFz/Go3/SQ3x8wvCvtV9TM1PqLZIZt9P0d4NV6/OpeWjVQ=@vger.kernel.org, AJvYcCXgL1ceJ2h9D5IAsKLpQAIMqaQHwCM2Q/pNKiyIXqsVysY2SB2+3EzotBfl/rItAK55jJPJeZwFaWllHGS/@vger.kernel.org X-Gm-Message-State: AOJu0YxAcwrgkDXc4NVrQasjOLXrCXgkl5qxg39W4m/oPq9yGZxBGTGu QS0K6fzoq/UGdpbezqDDn1etH/ouY6EcO3zW+x6Uw3GJ7HIZGIVXvZrA X-Gm-Gg: ASbGncu048cUUkvhKFNODpw2hzQ03Dw6cgdvrIOapFM54Khah8wgjgF+xiqppxb7C1J /0O6qSLWcsB2OOXmHtVAZj6SMrFWVgEltuMILi8u/xWx+QU8LehYWOtdSaTtDYpHbgiDDOsD35X 6qgi7IGdyUlyZ1o+ep4lXpm5tJuB+95rNhZZ/NmvqzweRpybpI79wG9L59vUHRgV/z5kS5X4Xwf BMlnb/JvvAtA2ytfx3JeSnL6hSjASovK+gLZRGWnDR5DyT9uW47KwuvS9bNglYawgDq19fJPElq LzPjEgVLbKBjv9kTM900nqHcDsokUlLh1vDq6NdKF/VKH5hQcI3f X-Google-Smtp-Source: AGHT+IEKuh5P5XxfGU6tISC7d/SWRHDTdhtCdRwTY574SCwgIN9VltFkhI6/5VSmmx/mAhn8r/NsaQ== X-Received: by 2002:a17:907:97d0:b0:ae3:7022:b210 with SMTP id a640c23a62f3a-ae6b0b1ec6amr238872866b.12.1751967599680; Tue, 08 Jul 2025 02:39:59 -0700 (PDT) Received: from gmail.com ([2a03:2880:30ff:9::]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-ae3f66e6f30sm864599066b.33.2025.07.08.02.39.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Jul 2025 02:39:58 -0700 (PDT) Date: Tue, 8 Jul 2025 02:39:56 -0700 From: Breno Leitao To: Mark Rutland Cc: Catalin Marinas , Will Deacon , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, leo.yan@arm.com, kernel-team@meta.com Subject: Re: [PATCH 1/8] arm64: Enable VMAP_STACK support Message-ID: References: <20250707-arm64_vmap-v1-0-8de98ca0f91c@debian.org> <20250707-arm64_vmap-v1-1-8de98ca0f91c@debian.org> Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hello Mark, On Mon, Jul 07, 2025 at 06:23:09PM +0100, Mark Rutland wrote: > On Mon, Jul 07, 2025 at 09:01:01AM -0700, Breno Leitao wrote: > > Enable virtually mapped kernel stacks for ARM64. This provides better > > stack overflow detection and improved security by mapping kernel stacks > > in vmalloc space rather than using direct mapping. > > > > VMAP_STACK helps catch stack overflows early by placing guard pages > > around kernel stacks, and also provides better isolation between > > kernel stacks and other kernel data structures. > > > > All dependencies are satisfied for arm64: HAVE_ARCH_VMAP_STACK is > > already selected above, and KASAN_VMALLOC is selected when KASAN is > > enabled, meeting the KASAN dependency requirements. > > I reckon it might be better to say something like: > > | arm64: Mandate VMAP_STACK > | > | On arm64, VMAP_STACK has been enabled by default for a while now, and > | the only reason to disable it was a historical lack of support for > | KASAN_VMALLOC. Today there's no good reason to disable VMAP_STACK. > | > | Mandate VMAP_STACK, which will allow code to be simplified in > | subsequent patches. > > ... to make it clear that we're not changing the default, and we are > removing the ability to deselect VMAP_STACK. > > Either way, the patch itself looks good to me. Thanks for the suggestion. I will update and respin. Thanks for the review, --breno