On 26/01/2026 09:26, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <[email protected]>
> 
> 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 <[email protected]>

Reviewed-by: Ryan Roberts <[email protected]>

> ---
>  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);
>  
>                       /*


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