[U-Boot] [PATCH] efi_loader: make pool allocations cacheline aligned

[Rob Clark]

On Wed, Aug 2, 2017 at 11:24 AM, Brüns, Stefan
<Stefan.Bruens at rwth-aachen.de> wrote:
> On Mittwoch, 2. August 2017 11:28:37 CEST Rob Clark wrote:
>> On Tue, Aug 1, 2017 at 9:10 PM, Heinrich Schuchardt
> [...]
>> >>
>> >> @@ -356,7 +356,8 @@ efi_status_t efi_allocate_pool(int pool_type,
>> >> unsigned long size,>>
>> >>  {
>> >>
>> >>       efi_status_t r;
>> >>       efi_physical_addr_t t;
>> >>
>> >> -     u64 num_pages = (size + sizeof(u64) + EFI_PAGE_MASK) >>
>> >> EFI_PAGE_SHIFT; +     u64 num_pages = DIV_ROUND_UP(size + sizeof(struct
>> >> efi_pool_allocation), +                                  EFI_PAGE_SIZE);
>> >>
>> >>       if (size == 0) {
>> >>
>> >>               *buffer = NULL;
>> >
>> > NAK
>> >
>> > With DIV_ROUND_UP you introduce a 64bit division. Depending on the
>> > architecture this is only available via stdlib which is not available in
>> > U-Boot.
>>
>> The divisor is a constant power of two so compiler should turn this into a
>> shift
>> > Please, use
>> > + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
>> > as in the original line.
>>
>> This was actually incorrect (missing a "- 1"), which is why I decided
>> to stop open-coding DIV_ROUND_UP().
>
> EFI_PAGE_MASK == EFI_PAGE_SIZE - 1
>

Oh, you're right, I was reading that as PAGE_SIZE, not PAGE_MASK.  All
the more reason we should use DIV_ROUND_UP().

BR,
-R