From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 E04AD3CBE79; Fri, 17 Jul 2026 11:07:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784286446; cv=none; b=q3IKrMTvYGh6h9+Aycd3RapFJkCNzKjXZJZZl40lhMO9G2UZ+AAP2n2LK2ixrBpNYznTiAZhrqhpHLRn70+SwImhTRXdJnJVkT2zBBycfJ4sevfK+HSqEqZlVTnWsB+JxxaILOVEFuK/x3kYre8+1WmQspDycUWBmofqRUZnSh8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784286446; c=relaxed/simple; bh=4kBO8qX+9n4HtoX8f7rzuw8LYcyzRA912E90vgxtXFk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=kvOeVL1+vxBDBw2fjH6ihvS6Gkr2rnkYM5FscvoRr4LOmZMej+5rztWfrJDhR6xNQzuM5UgB9Vbp6vd3kTxa+DigDWXQTBDxMeYQsScOvIZyrNnHSnorkMpIwxxzprKTtZxHuhXSvCGU/nut9fCde7v4hP+jFwWioIy431UtISw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dofqD/NC; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dofqD/NC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 127941F000E9; Fri, 17 Jul 2026 11:07:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1784286431; bh=Qrt7GBm/iJQ0xT9tqvtXBOMrwF7xCOTKxp85twwhy4Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=dofqD/NCUtNXFT9e8cRUAwguEXHfd4naRLtJsBEqKHztpkIsDx6WdpAw2MAVdD5uI AcGqpJE2MSWyL/nGIL3P7ZfaiAs5OVbzN1Uqfl4wg+BUNzSbxkP42GeDU57JZcmsfM mZpPXlODsl0UyzEUJZzWB54Ennfw0y+vGO65uDkTeblfAvTVDelxnwEwSmk9lebpSz 9JcTyxOw6hTZwcy8p6SqIl4MBjYRxNWt9EAxtNxoBgM0I90+BLTOIil+rME3GzFUmh 00nkZf1BusqqTzJrGRGYb9SB9CwMG1L8LdLDhBoNzD8Mqk35OnU/6DuK5JwtItfzGg AoMS0YgO6HCnw== Date: Fri, 17 Jul 2026 12:06:55 +0100 From: "Lorenzo Stoakes (ARM)" To: Andrew Morton Cc: "Liam R. Howlett" , Vlastimil Babka , Jann Horn , Pedro Falcato , Alexander Viro , Christian Brauner , Jan Kara , Kees Cook , David Hildenbrand , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Leon Hwang Subject: Re: [PATCH 3/3] mm/mseal: remove further superfluous comments, do_mseal() Message-ID: References: <20260716-mseal-fixups-v1-0-3a9609bf041b@kernel.org> <20260716-mseal-fixups-v1-3-3a9609bf041b@kernel.org> <20260716173355.41a98b4e5d5a06772fd7fc12@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260716173355.41a98b4e5d5a06772fd7fc12@linux-foundation.org> On Thu, Jul 16, 2026 at 05:33:55PM -0700, Andrew Morton wrote: > On Thu, 16 Jul 2026 14:43:11 +0100 "Lorenzo Stoakes (ARM)" wrote: > > > There's no need to abstract do_mseal() any longer so put the system call > > implementation in the system call declaration. > > > > The comment around do_mseal() is strangely formatted, overly long and adds > > a lot of superfluous information that the code already provides, so boil it > > down to the essentials. > > > > This patch > (https://lore.kernel.org/20260716-mseal-fixups-v1-3-3a9609bf041b@kernel.org) > overlaps muchly with Leon's "mm/mseal: fix mseal documentation for > 32-bit kernels" > (https://lore.kernel.org/20260715131258.55499-1-leon.hwang@linux.dev). > > I'll remove the mseal.c changes from Leon's patch and I'll retain the > rest of that patch, after adjusting its changelog. Please check all of > this! Thanks! And sorry Leon - we definitely don't need the majority of the comments in mseal.c - so this change essentially makes those changes of yours unnecessary here. > > > Here's what's left of Leon's patch: > > From: Leon Hwang > Subject: mm/mseal: fix mseal documentation for 32-bit kernels > Date: Wed, 15 Jul 2026 21:12:58 +0800 > > mseal.o is built only for 64-bit kernels, so 32-bit kernels fall back to > sys_ni_syscall() and return -ENOSYS rather than -EPERM. > > Drop architecture description in mseal.rst, since the arch feature doc has > the latest state of mseal for each architecture. > > Fix the CONFIG_MSEAL_SYSTEM_MAPPINGS typo in init/Kconfig. > > Link: https://lore.kernel.org/20260715131258.55499-1-leon.hwang@linux.dev > Signed-off-by: Leon Hwang > Acked-by: Lance Yang > Cc: Alice Ryhl > Cc: Anand Moon > Cc: Doug Anderson > Cc: Gary Guo > Cc: Jann Horn > Cc: Jonathan Corbet > Cc: Leon Hwang > Cc: Liam R. Howlett > Cc: Lorenzo Stoakes > Cc: Miguel Ojeda > Cc: Nathan Chancellor > Cc: Pedro Falcato > Cc: Peter Zijlstra > Cc: Randy Dunlap > Cc: Thomas Weißschuh > Cc: Vlastimil Babka > Signed-off-by: Andrew Morton > --- > > Documentation/userspace-api/mseal.rst | 14 ++++++-------- > init/Kconfig | 2 +- > 2 files changed, 7 insertions(+), 9 deletions(-) > > --- a/Documentation/userspace-api/mseal.rst~mm-mseal-fix-mseal-documentation-for-32-bit-kernels > +++ a/Documentation/userspace-api/mseal.rst > @@ -50,8 +50,8 @@ mseal syscall signature > * The start address (``addr``) is not allocated. > * The end address (``addr`` + ``len``) is not allocated. > * A gap (unallocated memory) between start and end address. > - - **-EPERM**: > - * sealing is supported only on 64-bit CPUs, 32-bit is not supported. > + - **-ENOSYS**: > + * The kernel does not implement ``mseal()``. > > **Note about error return**: > - For above error cases, users can expect the given memory range is > @@ -62,7 +62,8 @@ mseal syscall signature > memory range could happen. However, those cases should be rare. > > **Architecture support**: > - mseal only works on 64-bit CPUs, not 32-bit CPUs. > + mseal is built only for 64-bit kernels. 32-bit kernels return > + ``-ENOSYS``. > > **Idempotent**: > users can call mseal multiple times. mseal on an already sealed memory > @@ -131,11 +132,11 @@ Use cases > - Chrome browser: protect some security sensitive data structures. > > - System mappings: > - The system mappings are created by the kernel and includes vdso, vvar, > + The system mappings are created by the kernel and include vdso, vvar, > vvar_vclock, vectors (arm compat-mode), sigpage (arm compat-mode), uprobes. > > Those system mappings are readonly only or execute only, memory sealing can > - protect them from ever changing to writable or unmmap/remapped as different > + protect them from ever changing to writable or unmapped/remapped as different > attributes. This is useful to mitigate memory corruption issues where a > corrupted pointer is passed to a memory management system. > > @@ -143,9 +144,6 @@ Use cases > the CONFIG_MSEAL_SYSTEM_MAPPINGS seals all system mappings of this > architecture. > > - The following architectures currently support this feature: x86-64, arm64, > - loongarch and s390. > - > WARNING: This feature breaks programs which rely on relocating > or unmapping system mappings. Known broken software at the time > of writing includes CHECKPOINT_RESTORE, UML, gVisor, rr. Therefore > --- a/init/Kconfig~mm-mseal-fix-mseal-documentation-for-32-bit-kernels > +++ a/init/Kconfig > @@ -2120,7 +2120,7 @@ config ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPIN > from a kernel perspective. > > After the architecture enables this, a distribution can set > - CONFIG_MSEAL_SYSTEM_MAPPING to manage access to the feature. > + CONFIG_MSEAL_SYSTEM_MAPPINGS to manage access to the feature. > > For complete descriptions of memory sealing, please see > Documentation/userspace-api/mseal.rst > _ > LGTM! Cheers, Lorenzo