[PATCH v5 1/4] powerpc/mm: refactor radix physical page mapping

[Balbir Singh]

On Mon, Jan 16, 2017 at 01:07:43PM -0600, Reza Arbab wrote:
> Move the page mapping code in radix_init_pgtable() into a separate
> function that will also be used for memory hotplug.
> 
> The current goto loop progressively decreases its mapping size as it
> covers the tail of a range whose end is unaligned. Change this to a for
> loop which can do the same for both ends of the range.
> 
> Signed-off-by: Reza Arbab <arbab at linux.vnet.ibm.com>
> ---
>  arch/powerpc/mm/pgtable-radix.c | 88 +++++++++++++++++++++++------------------
>  1 file changed, 50 insertions(+), 38 deletions(-)
> 
> diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
> index 623a0dc..2ce1354 100644
> --- a/arch/powerpc/mm/pgtable-radix.c
> +++ b/arch/powerpc/mm/pgtable-radix.c
> @@ -107,54 +107,66 @@ int radix__map_kernel_page(unsigned long ea, unsigned long pa,
>  	return 0;
>  }
>  
> +static inline void __meminit print_mapping(unsigned long start,
> +					   unsigned long end,
> +					   unsigned long size)
> +{
> +	if (end <= start)
> +		return;

Should we pr_err for start > end?

> +
> +	pr_info("Mapped range 0x%lx - 0x%lx with 0x%lx\n", start, end, size);
> +}
> +
> +static int __meminit create_physical_mapping(unsigned long start,
> +					     unsigned long end)
> +{
> +	unsigned long addr, mapping_size;
> +
> +	start = _ALIGN_UP(start, PAGE_SIZE);
> +	for (addr = start; addr < end; addr += mapping_size) {
> +		unsigned long gap, previous_size;
> +		int rc;
> +
> +		gap = end - addr;
> +		previous_size = mapping_size;
> +
> +		if (IS_ALIGNED(addr, PUD_SIZE) && gap >= PUD_SIZE &&
> +		    mmu_psize_defs[MMU_PAGE_1G].shift)
> +			mapping_size = PUD_SIZE;
> +		else if (IS_ALIGNED(addr, PMD_SIZE) && gap >= PMD_SIZE &&
> +			 mmu_psize_defs[MMU_PAGE_2M].shift)
> +			mapping_size = PMD_SIZE;
> +		else
> +			mapping_size = PAGE_SIZE;
> +
> +		if (mapping_size != previous_size) {
> +			print_mapping(start, addr, previous_size);
> +			start = addr;
> +		}
> +
> +		rc = radix__map_kernel_page((unsigned long)__va(addr), addr,
> +					    PAGE_KERNEL_X, mapping_size);
> +		if (rc)
> +			return rc;

Should we try a lower page size if map_kernel_page fails for this mapping_size?
I like the cleanup very much, BTW

Balbir Singh.