Re: [PATCH V4 3/7] arm64/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT

Anshuman Khandual
2022-04-08T11:19:17Z

On 4/8/22 15:58, Catalin Marinas wrote:
> On Thu, Apr 07, 2022 at 04:02:47PM +0530, Anshuman Khandual wrote:
>> diff --git a/arch/arm64/mm/mmap.c b/arch/arm64/mm/mmap.c
>> index 77ada00280d9..307534fcec00 100644
>> --- a/arch/arm64/mm/mmap.c
>> +++ b/arch/arm64/mm/mmap.c
>> @@ -55,3 +55,36 @@ static int __init adjust_protection_map(void)
>> return 0;
>> }
>> arch_initcall(adjust_protection_map);
>> +
>> +static pgprot_t arm64_arch_vm_get_page_prot(unsigned long vm_flags)
>> +{
>> + pteval_t prot = 0;
>> +
>> + if (vm_flags & VM_ARM64_BTI)
>> + prot |= PTE_GP;
>> +
>> + /*
>> + * There are two conditions required for returning a Normal Tagged
>> + * memory type: (1) the user requested it via PROT_MTE passed to
>> + * mmap() or mprotect() and (2) the corresponding vma supports MTE. We
>> + * register (1) as VM_MTE in the vma->vm_flags and (2) as
>> + * VM_MTE_ALLOWED. Note that the latter can only be set during the
>> + * mmap() call since mprotect() does not accept MAP_* flags.
>> + * Checking for VM_MTE only is sufficient since arch_validate_flags()
>> + * does not permit (VM_MTE & !VM_MTE_ALLOWED).
>> + */
>> + if (vm_flags & VM_MTE)
>> + prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED);
>> +
>> + return __pgprot(prot);
>> +}
>> +
>> +pgprot_t vm_get_page_prot(unsigned long vm_flags)
>> +{
>> + pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
>> + (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
>> + pgprot_val(arm64_arch_vm_get_page_prot(vm_flags)));
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL(vm_get_page_prot);
>
> Could you write all this in a single function? I think I mentioned it in
> a previous series (untested):

Right, missed that.

>
> pgprot_t vm_get_page_prot(unsigned long vm_flags)
> {
> pteval_t prot = pgprot_val(protection_map[vm_flags &
> (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]);
>
> if (vm_flags & VM_ARM64_BTI)
> prot |= PTE_GP;
>
> /*
> * There are two conditions required for returning a Normal Tagged
> * memory type: (1) the user requested it via PROT_MTE passed to
> * mmap() or mprotect() and (2) the corresponding vma supports MTE. We
> * register (1) as VM_MTE in the vma->vm_flags and (2) as
> * VM_MTE_ALLOWED. Note that the latter can only be set during the
> * mmap() call since mprotect() does not accept MAP_* flags.
> * Checking for VM_MTE only is sufficient since arch_validate_flags()
> * does not permit (VM_MTE & !VM_MTE_ALLOWED).
> */
> if (vm_flags & VM_MTE)
> prot |= PTE_ATTRINDX(MT_NORMAL_TAGGED);
>
> return __pgprot(prot);
> }
> EXPORT_SYMBOL(vm_get_page_prot);
>
> With that:

Sure, will change them into a single function.

>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>