On 26/01/2026 09:26, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> Instead of blindly overwriting an existing table entry when mapping DRAM
> regions, take care not to replace a pre-existing table entry with a
> block entry. This permits the logic of mapping the kernel's linear alias
> to be simplified in a subsequent patch.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
> arch/arm64/mm/mmu.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 9d39de3cfe67..28cc3cda042c 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -262,7 +262,8 @@ static int init_pmd(pmd_t *pmdp, unsigned long addr, unsigned long end,
>
> /* try section mapping first */
> if (((addr | next | phys) & ~PMD_MASK) == 0 &&
> - (flags & NO_BLOCK_MAPPINGS) == 0) {
> + (flags & NO_BLOCK_MAPPINGS) == 0 &&
> + !pmd_table(old_pmd)) {
> pmd_set_huge(pmdp, phys, prot);
>
> /*
> @@ -385,7 +386,8 @@ static int alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end,
> */
> if (pud_sect_supported() &&
> ((addr | next | phys) & ~PUD_MASK) == 0 &&
> - (flags & NO_BLOCK_MAPPINGS) == 0) {
> + (flags & NO_BLOCK_MAPPINGS) == 0 &&
> + !pud_table(old_pud)) {
> pud_set_huge(pudp, phys, prot);
>
> /*