Re: [PATCH v4 15/15] arm64: mm: Remap linear aliases of the fixmap page tables read-only

Kevin Brodsky
2026-04-29T13:57:36Z

On 27/04/2026 17:34, Ard Biesheuvel wrote:
> [...]
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 84d81bae07a7..e76fe5b0c5fe 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -1076,6 +1076,11 @@ void __init mark_linear_text_alias_ro(void)
> (unsigned long)__init_begin - (unsigned long)_text,
> pgprot_tagged(PAGE_KERNEL_RO));
>
> + /* Map the fixmap PTE table at __fixmap_pgdir_start R/O in linear map too */
> + update_mapping_prot(__pa_symbol(__fixmap_pgdir_start),
> + (unsigned long)lm_alias(__fixmap_pgdir_start),
> + PAGE_SIZE, pgprot_tagged(PAGE_KERNEL_RO));

Is that definitely just one page?

> +
> remap_linear_data_alias(true);
>
> if (IS_ENABLED(CONFIG_HIBERNATION)) {