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SubjectRe: [PATCH REBASE v4 05/14] arm64, mm: Make randomization selected by generic topdown mmap layout
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On 7/24/19 7:11 PM, Luis Chamberlain wrote:
> On Wed, Jul 24, 2019 at 01:58:41AM -0400, Alexandre Ghiti wrote:
>> diff --git a/mm/util.c b/mm/util.c
>> index 0781e5575cb3..16f1e56e2996 100644
>> --- a/mm/util.c
>> +++ b/mm/util.c
>> @@ -321,7 +321,15 @@ unsigned long randomize_stack_top(unsigned long stack_top)
>> }
>>
>> #ifdef CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
>> -#ifdef CONFIG_ARCH_HAS_ELF_RANDOMIZE
>> +unsigned long arch_randomize_brk(struct mm_struct *mm)
>> +{
>> + /* Is the current task 32bit ? */
>> + if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task())
>> + return randomize_page(mm->brk, SZ_32M);
>> +
>> + return randomize_page(mm->brk, SZ_1G);
>> +}
>> +
>> unsigned long arch_mmap_rnd(void)
>> {
>> unsigned long rnd;
>> @@ -335,7 +343,6 @@ unsigned long arch_mmap_rnd(void)
>>
>> return rnd << PAGE_SHIFT;
>> }
> So arch_randomize_brk is no longer ifdef'd around
> CONFIG_ARCH_HAS_ELF_RANDOMIZE either and yet the header
> still has it. Is that intentional?
>

Yes, CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects
CONFIG_ARCH_HAS_ELF_RANDOMIZE, that's what's new about v4: the generic
functions proposed in this series come with elf randomization.


Alex


> Luis
>
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> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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