Re: [PATCH -fixes] riscv: Check the virtual alignment before choosing a map size

[Jessica Clarke]

On 7 Jun 2023, at 13:58, Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> wrote:
> 
> We used to only check the alignment of the physical address to decide
> which mapping would fit for a certain region of the linear mapping, but
> it is not enough since the virtual address must also be aligned, so check
> that too.
> 
> Fixes: 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear mapping")
> Reported-by: Song Shuai <songshuaishuai@xxxxxxxxxxx>
> Link: https://lore.kernel.org/linux-riscv/tencent_7C3B580B47C1B17C16488EC1@xxxxxx/
> Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
> ---
> arch/riscv/mm/init.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index d42ea31c7de0..5143eef4c074 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -660,18 +660,19 @@ void __init create_pgd_mapping(pgd_t *pgdp,
> create_pgd_next_mapping(nextp, va, pa, sz, prot);
> }
> 
> -static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
> +static uintptr_t __init best_map_size(phys_addr_t pa, uintptr_t va,

Why on earth is this returning uintptr_t? It’s a size not a pointer.

Jess

> +      phys_addr_t size)
> {
> - if (!(base & (PGDIR_SIZE - 1)) && size >= PGDIR_SIZE)
> + if (!(pa & (PGDIR_SIZE - 1)) && !(va & (PGDIR_SIZE - 1)) && size >= PGDIR_SIZE)
> return PGDIR_SIZE;
> 
> - if (!(base & (P4D_SIZE - 1)) && size >= P4D_SIZE)
> + if (!(pa & (P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
> return P4D_SIZE;
> 
> - if (!(base & (PUD_SIZE - 1)) && size >= PUD_SIZE)
> + if (!(pa & (PUD_SIZE - 1)) && !(va & (PUD_SIZE - 1)) && size >= PUD_SIZE)
> return PUD_SIZE;
> 
> - if (!(base & (PMD_SIZE - 1)) && size >= PMD_SIZE)
> + if (!(pa & (PMD_SIZE - 1)) && !(va & (PMD_SIZE - 1)) && size >= PMD_SIZE)
> return PMD_SIZE;
> 
> return PAGE_SIZE;
> @@ -1177,7 +1178,7 @@ static void __init create_linear_mapping_range(phys_addr_t start,
> for (pa = start; pa < end; pa += map_size) {
> va = (uintptr_t)__va(pa);
> map_size = fixed_map_size ? fixed_map_size :
> -    best_map_size(pa, end - pa);
> +    best_map_size(pa, va, end - pa);
> 
> create_pgd_mapping(swapper_pg_dir, va, pa, map_size,
>   pgprot_from_va(va));
> -- 
> 2.39.2
> 
> 
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