From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Ard Biesheuvel <ardb+git@google.com>, linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org, will@kernel.org,
catalin.marinas@arm.com, mark.rutland@arm.com,
Ard Biesheuvel <ardb@kernel.org>,
Ryan Roberts <ryan.roberts@arm.com>,
Liz Prucka <lizprucka@google.com>,
Seth Jenkins <sethjenkins@google.com>,
Kees Cook <kees@kernel.org>,
linux-hardening@vger.kernel.org
Subject: Re: [PATCH 3/4] arm64: Move the zero page to rodata
Date: Fri, 23 Jan 2026 12:13:23 +0530 [thread overview]
Message-ID: <ddb667ef-efd1-40f5-832d-9017f6bbbec5@arm.com> (raw)
In-Reply-To: <20260119164747.1402434-9-ardb+git@google.com>
On 19/01/26 10:17 PM, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> The zero page should contain only zero bytes, and so mapping it
> read-write is unnecessary. Move it to __ro_after_init instead.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/arm64/mm/mmu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 2a18637ecc15..d978b07ab7b8 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -68,7 +68,8 @@ long __section(".mmuoff.data.write") __early_cpu_boot_status;
> * Empty_zero_page is a special page that is used for zero-initialized data
> * and COW.
> */
> -unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
> +unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
> + __ro_after_init __aligned(PAGE_SIZE);
> EXPORT_SYMBOL(empty_zero_page);
>
> static DEFINE_SPINLOCK(swapper_pgdir_lock);
A small nit - could this be the first patch in the series here ? Becasue it is
not related to other three patches.
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
next prev parent reply other threads:[~2026-01-23 6:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-19 16:47 [PATCH 0/4] arm64: Unmap linear alias of kernel data/bss Ard Biesheuvel
2026-01-19 16:47 ` [PATCH 1/4] arm64: Move fixmap page tables to end of kernel image Ard Biesheuvel
2026-01-23 6:12 ` Anshuman Khandual
2026-01-23 6:43 ` Ard Biesheuvel
2026-01-19 16:47 ` [PATCH 2/4] arm64: Map the kernel data/bss read-only in the linear map Ard Biesheuvel
2026-01-23 6:32 ` Anshuman Khandual
2026-01-19 16:47 ` [PATCH 3/4] arm64: Move the zero page to rodata Ard Biesheuvel
2026-01-23 6:43 ` Anshuman Khandual [this message]
2026-01-23 6:44 ` Ard Biesheuvel
2026-01-19 16:47 ` [PATCH 4/4] arm64: Unmap kernel data/bss entirely from the linear map Ard Biesheuvel
2026-01-23 6:52 ` Anshuman Khandual
2026-01-23 7:27 ` Ard Biesheuvel
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