linux-kernel - Re: [PATCH -next,v2] efi/libstub: arm32: Use "align" for the size alignment

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Message-ID: <6bd8e85e-2ff8-f833-0b5b-2868b61f2f34@huawei.com>
Date:   Mon, 8 Nov 2021 20:48:02 +0800
From:   cuigaosheng <cuigaosheng1@...wei.com>
To:     Ard Biesheuvel <ardb@...nel.org>
CC:     linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        <wangweiyang2@...wei.com>
Subject: Re: [PATCH -next,v2] efi/libstub: arm32: Use "align" for the size
 alignment

Hi Ard,

Thanks for your reply.

In my understanding address and size need to meet consistent alignment 
constraints,If I understand wrong, please reject this patch.

Best,

GaoSheng.

在 2021/11/4 17:26, Ard Biesheuvel 写道:
> On Tue, 2 Nov 2021 at 03:04, Gaosheng Cui <cuigaosheng1@...wei.com> wrote:
>> We are doing page-based allocations, and both the address
>> and size must meet alignment constraints, so using "align"
>> for the size alignment is a better choice.
>>
> Why is it a better choice? If I allocate a 2 MB aligned block of
> memory, why is it better to align the size to a multiple of 2 MB as
> well?
>
>
>> Signed-off-by: Gaosheng Cui <cuigaosheng1@...wei.com>
>> ---
>>   drivers/firmware/efi/libstub/randomalloc.c | 2 +-
>>   drivers/firmware/efi/libstub/relocate.c    | 2 +-
>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/libstub/randomalloc.c b/drivers/firmware/efi/libstub/randomalloc.c
>> index 724155b9e10d..7b7159bb035d 100644
>> --- a/drivers/firmware/efi/libstub/randomalloc.c
>> +++ b/drivers/firmware/efi/libstub/randomalloc.c
>> @@ -76,7 +76,7 @@ efi_status_t efi_random_alloc(unsigned long size,
>>          if (align < EFI_ALLOC_ALIGN)
>>                  align = EFI_ALLOC_ALIGN;
>>
>> -       size = round_up(size, EFI_ALLOC_ALIGN);
>> +       size = round_up(size, align);
>>
>>          /* count the suitable slots in each memory map entry */
>>          for (map_offset = 0; map_offset < map_size; map_offset += desc_size) {
>> diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c
>> index 8ee9eb2b9039..d6d27e8c23f8 100644
>> --- a/drivers/firmware/efi/libstub/relocate.c
>> +++ b/drivers/firmware/efi/libstub/relocate.c
>> @@ -50,7 +50,7 @@ efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
>>          if (align < EFI_ALLOC_ALIGN)
>>                  align = EFI_ALLOC_ALIGN;
>>
>> -       size = round_up(size, EFI_ALLOC_ALIGN);
>> +       size = round_up(size, align);
>>          nr_pages = size / EFI_PAGE_SIZE;
>>          for (i = 0; i < map_size / desc_size; i++) {
>>                  efi_memory_desc_t *desc;
>> --
>> 2.30.0
>>
> .