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SubjectRe: [PATCH 1/4] arm64, mm: Move generic mmap layout functions to mm
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On 3/22/19 9:21 AM, Christoph Hellwig wrote:
>> It then introduces a new define ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
>> that can be defined by other architectures to benefit from those functions.
> Can you make this a Kconfig option defined in arch/Kconfig or mm/Kconfig
> and selected by the architectures?


Yes, I will do.


>> -#ifndef STACK_RND_MASK
>> -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
>> -#endif
>> -
>> -static unsigned long randomize_stack_top(unsigned long stack_top)
>> -{
>> - unsigned long random_variable = 0;
>> -
>> - if (current->flags & PF_RANDOMIZE) {
>> - random_variable = get_random_long();
>> - random_variable &= STACK_RND_MASK;
>> - random_variable <<= PAGE_SHIFT;
>> - }
>> -#ifdef CONFIG_STACK_GROWSUP
>> - return PAGE_ALIGN(stack_top) + random_variable;
>> -#else
>> - return PAGE_ALIGN(stack_top) - random_variable;
>> -#endif
>> -}
>> -
> Maybe the move of this function can be split into another prep patch,
> as it is only very lightly related?
>
>

Ok, that makes sense.

>> +#if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \
>> + defined(ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT)
> Not sure if it is wrіtten down somehwere or just convention, but I
> general see cpp defined statements aligned with spaces to the
> one on the previous line.


Ok, I will fix that.


> Except for these nitpicks this looks very nice to me, thanks for doing
> this work!


Thanks :)

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