From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 402A5FD3758 for ; Wed, 25 Feb 2026 13:32:48 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 799506B008A; Wed, 25 Feb 2026 08:32:47 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 74D2F6B008C; Wed, 25 Feb 2026 08:32:47 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 65C906B0092; Wed, 25 Feb 2026 08:32:47 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 53E446B008A for ; Wed, 25 Feb 2026 08:32:47 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id E146A1C799 for ; Wed, 25 Feb 2026 13:32:46 +0000 (UTC) X-FDA: 84483069132.08.77D0750 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf10.hostedemail.com (Postfix) with ESMTP id 1C49DC0004 for ; Wed, 25 Feb 2026 13:32:44 +0000 (UTC) Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=lowN1fXa; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772026365; a=rsa-sha256; cv=none; b=W6XzZLcZ9F7b7ewjJkJqScquSPvwKWD+t6l5rgVFWWQJyraKB0nApZ0EGNnzl1GaWUZWiF B8ouCgFJ1MchtteAsHZwUZa8qDzW+HC+YFUwxnMy2QGYdgZi+W8LJyGW5qDidsAJvXy7ku 1D9RwQARUfsf/HX8YzCh1kfFvS8WIbo= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=lowN1fXa; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf10.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772026365; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=a4eMnlk159rc+pn8tPeNwlSEScn9DtiHuFZwPn08Y9E=; b=h+/gsXggjJrqJIZxaXf1D6pLG2yywIH5JqX0pqtmzGueiIG5972taMVSZ/t28mqUJiYexb d9idGddwTdC53giPNSQ5lAnkApKHFp7Vw7rRy4wSrTrzyAcn5RHMu41wF7mWtVoUs/BmB4 vMx0+NFmGykABqDBKF9AJHJle/6hnOI= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 6479860097; Wed, 25 Feb 2026 13:32:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 92A4EC116D0; Wed, 25 Feb 2026 13:32:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772026364; bh=93Mh71NbG5+oh8SLMr+D80K3rtiPszgWs+oYcu1c38s=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=lowN1fXaUvgh5wPI9HCoKY61vts/SWKwO5aaYnlNh146Rw6q7d1D74Mt3+DD5NF71 mGg1Pp4VsVHnrGiDO6U2JLibIp68k2I8Y1n+OlevEow7KeFLe9C+TuEilx0mRtDuAG YwTXeT5dCEjM0WmIgeV8Qo8FrOQKsMzRUf4+BlyC+5e9tLDgDGrrKXlGRFQNUCzXuY cTpoWSkwo6g6R1MG8BC/xY0sOm5N3DFQMlvcktTKLqikygNbu0BxNs9TGwkUHMlVwh HcVvNn16aypGbGOboWEKm8UpLgKKYVU27r3tIHAuDbTDRagRVKmSA9ZbCV671ZD6s4 3eY0JRRpNXcUg== Message-ID: Date: Wed, 25 Feb 2026 14:32:37 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/5] mm: Introduce vm_mmap_shadow_stack() as a helper for VM_SHADOW_STACK mappings To: Catalin Marinas , Andrew Morton , Mark Brown , Deepak Gupta , Rick Edgecombe Cc: Will Deacon , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, linux-mm@kvack.org References: <20260224175800.2500729-1-catalin.marinas@arm.com> <20260224175800.2500729-2-catalin.marinas@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260224175800.2500729-2-catalin.marinas@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: ux5h9e1xydny1cdwbnr6jyahtfsnzn4q X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1C49DC0004 X-HE-Tag: 1772026364-486199 X-HE-Meta: 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 fNXZjWx0 mnR1FgpqX7ft6Df1auhs/CMdibgd0j53aW5Ebcetx7DVqUDep66lHtX1V3Vpqqz+ZyicVH6wrQjyngLUMW5jfY5ooBBW7Igzd1bYOLqk2UXbnyM5k1p9i09ZyQ8kLzY6Lq1o30fTRtWXzx6r3oyKxO/dMazdDDEAR7qtKx+sXVGocuG4VNXxF/a6XB8MtIbGyKvrQSTML98cPzk9V6O2kukGh509eULhhbyFBg7dotYyWBlmxZCZITVshi1bMREgPtE/vb9sAZDcV9L803raiEgl3+I5mcni1B/Ex63sukT/W2UAN/+NU3208E/2JfFHAsZmCGsF2zVsDEkm6kYhhLInPEndJcLbcM0rimx3BdKSLYjmhyJk+KaYoTE2rn9BJbYQ8BkZ6W/2SyfHAWlPnVwKX6A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2/24/26 18:57, Catalin Marinas wrote: > arm64, riscv and x86 use a similar pattern for mapping the user shadow > stack (cloned from x86). Extract this into a helper to facilitate code > reuse. > > The call to do_mmap() from the new helper uses PROT_READ|PROT_WRITE prot > bits instead of the PROT_READ with an explicit VM_WRITE vm_flag. The > x86 intent was to avoid PROT_WRITE implying normal write since the > shadow stack is not writable by normal stores. However, from a kernel > perspective, the vma is writeable. Functionally there is no difference. > > Signed-off-by: Catalin Marinas > Cc: Andrew Morton > Cc: David Hildenbrand > --- > include/linux/mm.h | 4 ++++ > mm/util.c | 25 +++++++++++++++++++++++++ > 2 files changed, 29 insertions(+) > > diff --git a/include/linux/mm.h b/include/linux/mm.h > index 5be3d8a8f806..1f28be975f86 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3908,6 +3908,10 @@ extern int vm_munmap(unsigned long, size_t); > extern unsigned long __must_check vm_mmap(struct file *, unsigned long, > unsigned long, unsigned long, > unsigned long, unsigned long); > +#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK > +extern unsigned long __must_check vm_mmap_shadow_stack(unsigned long addr, > + unsigned long len, unsigned long flags); MM nowadays tends to use two tabs here. > +#endif > > struct vm_unmapped_area_info { > #define VM_UNMAPPED_AREA_TOPDOWN 1 > diff --git a/mm/util.c b/mm/util.c > index b05ab6f97e11..2592291948f0 100644 > --- a/mm/util.c > +++ b/mm/util.c > @@ -618,6 +618,31 @@ unsigned long vm_mmap(struct file *file, unsigned long addr, > } > EXPORT_SYMBOL(vm_mmap); > > +#ifdef CONFIG_ARCH_HAS_USER_SHADOW_STACK > +/* > + * Perform a userland memory mapping for a shadow stack into the current > + * process address space. This is intended to be used by architectures that > + * support user shadow stacks. > + */ > +unsigned long vm_mmap_shadow_stack(unsigned long addr, unsigned long len, > + unsigned long flags) And here as well. Agreed that the ifdef for the function declaration is not required. Acked-by: David Hildenbrand (Arm) -- Cheers, David