Re: [PATCH 1/3] x86/mm: Simplify memory mapping PFN calculation

Yinghai Lu
2012-07-14T20:34:36Z

On Sat, Jul 14, 2012 at 6:41 AM, Pekka Enberg <penberg@kernel.org> wrote:
> Introduce two new helper functions, addr_to_pmd_pfn() and
> addr_to_pud_pfn(), to simplify init_memory_mapping() code flow.
>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Yinghai Lu <yinghai@kernel.org>
> Signed-off-by: Pekka Enberg <penberg@kernel.org>

Acked-by: Yinghai Lu <yinghai@kernel.org>

> ---
> arch/x86/mm/init.c | 38 +++++++++++++++++++++-----------------
> 1 files changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index bc4e9d8..9eb53c2 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -117,6 +117,16 @@ static int __meminit save_mr(struct map_range *mr, int nr_range,
> return nr_range;
> }
>
> +static unsigned long addr_to_pmd_pfn(unsigned long addr)
> +{
> + return (addr >> PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
> +}
> +
> +static unsigned long addr_to_pud_pfn(unsigned long addr)
> +{
> + return (addr >> PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
> +}
> +
> /*
> * Setup the direct mapping of the physical memory at PAGE_OFFSET.
> * This runs before bootmem is initialized and gets pages directly from
> @@ -180,11 +190,9 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
> if (pos == 0)
> end_pfn = 1<<(PMD_SHIFT - PAGE_SHIFT);
> else
> - end_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
> - << (PMD_SHIFT - PAGE_SHIFT);
> + end_pfn = addr_to_pmd_pfn(pos + (PMD_SIZE - 1));
> #else /* CONFIG_X86_64 */
> - end_pfn = ((pos + (PMD_SIZE - 1)) >> PMD_SHIFT)
> - << (PMD_SHIFT - PAGE_SHIFT);
> + end_pfn = addr_to_pmd_pfn(pos + (PMD_SIZE - 1));
> #endif
> if (end_pfn > (end >> PAGE_SHIFT))
> end_pfn = end >> PAGE_SHIFT;
> @@ -194,15 +202,13 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
> }
>
> /* big page (2M) range */
> - start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
> - << (PMD_SHIFT - PAGE_SHIFT);
> + start_pfn = addr_to_pmd_pfn(pos + (PMD_SIZE - 1));
> #ifdef CONFIG_X86_32
> - end_pfn = (end>>PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
> + end_pfn = addr_to_pmd_pfn(end);
> #else /* CONFIG_X86_64 */
> - end_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
> - << (PUD_SHIFT - PAGE_SHIFT);
> - if (end_pfn > ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT)))
> - end_pfn = ((end>>PMD_SHIFT)<<(PMD_SHIFT - PAGE_SHIFT));
> + end_pfn = addr_to_pud_pfn(pos + (PUD_SIZE - 1));
> + if (end_pfn > addr_to_pmd_pfn(end))
> + end_pfn = addr_to_pmd_pfn(end);
> #endif
>
> if (start_pfn < end_pfn) {
> @@ -213,9 +219,8 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
>
> #ifdef CONFIG_X86_64
> /* big page (1G) range */
> - start_pfn = ((pos + (PUD_SIZE - 1))>>PUD_SHIFT)
> - << (PUD_SHIFT - PAGE_SHIFT);
> - end_pfn = (end >> PUD_SHIFT) << (PUD_SHIFT - PAGE_SHIFT);
> + start_pfn = addr_to_pud_pfn(pos + (PUD_SIZE - 1));
> + end_pfn = addr_to_pud_pfn(end);
> if (start_pfn < end_pfn) {
> nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
> page_size_mask &
> @@ -224,9 +229,8 @@ unsigned long __init_refok init_memory_mapping(unsigned long start,
> }
>
> /* tail is not big page (1G) alignment */
> - start_pfn = ((pos + (PMD_SIZE - 1))>>PMD_SHIFT)
> - << (PMD_SHIFT - PAGE_SHIFT);
> - end_pfn = (end >> PMD_SHIFT) << (PMD_SHIFT - PAGE_SHIFT);
> + start_pfn = addr_to_pmd_pfn(pos + (PMD_SIZE - 1));
> + end_pfn = addr_to_pmd_pfn(end);
> if (start_pfn < end_pfn) {
> nr_range = save_mr(mr, nr_range, start_pfn, end_pfn,
> page_size_mask & (1<<PG_LEVEL_2M));
> --
> 1.7.7.6
>