linux-kernel - Re: [PATCH mm-unstable 2/2] mseal sysmap: enable s390

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Message-ID: <fd60672f-fa74-4180-8b10-d02f97886ff1@lucifer.local>
Date: Tue, 11 Mar 2025 14:37:07 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Heiko Carstens <hca@...ux.ibm.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>, Jeff Xu <jeffxu@...omium.org>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Kees Cook <kees@...nel.org>,
        Thomas Weißschuh <thomas.weissschuh@...utronix.de>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH mm-unstable 2/2] mseal sysmap: enable s390

On Tue, Mar 11, 2025 at 01:33:26PM +0100, Heiko Carstens wrote:
> Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on s390, covering the
> vdso.
>
> Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  arch/s390/Kconfig       | 1 +
>  arch/s390/kernel/vdso.c | 2 +-
>  2 files changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 608a965e2344..93b880992596 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -141,6 +141,7 @@ config S390
>  	select ARCH_SUPPORTS_DEBUG_PAGEALLOC
>  	select ARCH_SUPPORTS_HUGETLBFS
>  	select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && CC_IS_CLANG
> +	select ARCH_SUPPORTS_MSEAL_SYSTEM_MAPPINGS

As discussed in 0/2, s390 does not rely on remapping system mappings in any
kind of bizarre way so this is all good.

>  	select ARCH_SUPPORTS_NUMA_BALANCING
>  	select ARCH_SUPPORTS_PER_VMA_LOCK
>  	select ARCH_USE_BUILTIN_BSWAP
> diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
> index 70c8f9ad13cd..430feb1a5013 100644
> --- a/arch/s390/kernel/vdso.c
> +++ b/arch/s390/kernel/vdso.c
> @@ -80,7 +80,7 @@ static int map_vdso(unsigned long addr, unsigned long vdso_mapping_len)
>  	vdso_text_start = vvar_start + VDSO_NR_PAGES * PAGE_SIZE;
>  	/* VM_MAYWRITE for COW so gdb can set breakpoints */
>  	vma = _install_special_mapping(mm, vdso_text_start, vdso_text_len,
> -				       VM_READ|VM_EXEC|
> +				       VM_READ|VM_EXEC|VM_SEALED_SYSMAP|
>  				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
>  				       vdso_mapping);
>  	if (IS_ERR(vma)) {
> --
> 2.45.2
>